Research Outline - Gliese 581 Paper

8/10/2019 Research Outline - Gliese 581 Paper

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Gliese 581 Outline

About the star (1 page)

-spectral class, type, formation, red dwarf M3V, light years away, etc

Planetary systems (2 pages)

-possibilities of red dwarf planets and habitability, goldilocks zone, four planet solution, six planet

solution

Most likely inhabitants for life (2 pages)

-Gliese 581 d, Gliese 581 g, discuss each planet and the pros/cons versus planetary habitability

Conclusion (1 page)


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http://www.solstation.com/stars/gl581.htm

Gliese 581 / HO Librae

Home | Stars | Orbits | Habitability | Life |

NASA --largerimageGliese 581 is a dim red dwarf star, like Gliese623 A (M2.5V) and B (M5.8Ve) at lower right.(See a2MASS Surveyimageof Gl 581 fromtheNASA Star and Exoplanet Database.)

Breaking News

On May 5, 2011, a team of scientists submitted a pre-print on the results ofclimate model simulations which further clarified under what conditionsthat planet d might be warm enough to support liquid water on its surface.At its current orbital distance from its dim red dwarf, host star, planet dreceives "35% less stellar energy thanMarsand is probably locked in tidalresonance, with extremely low insolation at the poles and possibly apermanent night side" and so could be subject to "global glaciation and /or atmospheric collapse." If its atmosphere has more than 10 bars (10

times Earth's atmospheric pressure at sea level) of CO2and and othergases (such as molecular nitrogen, or N2), however, three-dimensionalclimate simulations suggest that the planet's global mean temperaturescould rise above freezing for land as well as ocean-covered surfaces(CNRSpress release;Wordsworth et al, 2011;andJon Voisey, UniverseToday, May 6, 2011).

LMD,CNRS

Largeran djumbo

i l lus tra t ions (source).

Model s imula t ions sug gest

that

Gl iese 581 d can be warm

enough

to have l iqu id water on i ts

surface

i f i ts atmosphere is
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suf f ic ient ly

th ick and r ich in CO2(mo re).

System Summary

Also known as HO Librae, this dim star lies around 20.4 light-years from Sol. It islocated in the northeast part (15:19:26.8-07:43:20.2, ICRS 2000.0) ofConstellationLibra,the Scales -- northeast of Delta Librae, north of GammaLibrae andGraffias(Beta Scorpii), and southwest of Epsilon (Yed Posterior)andDelta (Yed Prior)Ophiuchi, and Mu, Epsilon, and Alpha (Unukalhai)Serpentis.Like other red dwarf stars, it is not visible to unaided Human eyes from Earth.

ESO,unknown artist

Largerillustration.

Gliese 581 now appearsto host at least sixplanets between Earthand Neptune in mass(NASA2010 newsand ESO2007 news).

As of September 29, 2010, Gliese581 is believed to host at least six planets between the size ofEarthandNeptune,with one orbiting the star wholly within itshabitable zone.OnNovember 30, 2005, a team of French and Swiss astronomers announced thediscovery of aNeptune-class planet in a very close "torch" orbit around Gliese581 (ESOpress releaseandBonfils et al, 2005-- details below). On April 25,2007, astronomers using theEuropean Southern Observatory's 3.6-metertelescope announced the discovery of two additional lower-mass planets in thissystem, including the most Earth-like planet found outside the Solar System todate (a planet with a diameter that is one and a half as much wider than Earthwith at least five times Earth's mass of the Earth) and another planet with at leasteight Earth-masses, one of which may be capable of having liquid water on itssurface (ESOnews release;Udry et al, 2007;von Bloh et al, 2008;Observatoirede Genve's web page onGl 581;andAstronomy Picture of the Day-- morebelow). On April 21, 2009, a team of astronomers at the2009 European Week of
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Astronomy and Space Scienceconference announced the discovery of anotherplanetary candidate "e" with a minimum mass of 1.9 Earth-masses in aninnermost orbit, but revised orbital analysis and atmospheric modelling toindicate that planetary candidate "d" could have adeep global oceanand maynot be as hospitable to land-based, Earth-type plant and animal life despite an

orbit within the outer boundary of the habitable zone of Gliese 581 (ESOpressrelease;andMayor et al, 2009-- more below). On September 29, 2010, a teamof astronomers announced the discovery of a potentially habitable, rockysuper-Earthcandidate "g" orbiting wholly within the habitable zone ofGliese 581 as well as another larger but frigid super-Earth "f" in anoutermost orbit (NASAnews release;Carnegienews release;U.C. at SantaCruzpress release;NSFvideo announcement;Amir Alexander, PlanetaryNews, October 6, 2010;David Shiga, New Scient is t, September 29, 2010;Dennis Overbye, New York Times, September 29, 2010;Astronomy Pictureof the Day;andVogt et al, 2010-- more below). On October 11, 2010, anastronomer from theGeneva Observatory'sHARPSproject announced at

theIAU Symposium 276that their team had not been able to confirm theexistence of either planetary candidates Gliese 581 "g" or "f" based on onlytheir own, expanded but smaller dataset of 180 observations over 6.5 years(Leslie Mullen, Astrob io logy, October 12, 2010;andRachel Courtland, NewScient is t, October 13, 2010-- more below).

Lynette Cook(Ar twork from

Extrasolar Planets - Col lection III,

used wi th permiss ion)

Largeran dju mboi l lus tra t ions.

If i t exists, planetary candidate "g "

cou ld be to be a rockysuper-Earth

that orbi ts Gl iese 581 within t he red

dwarf star 's habitable zone (more).

This star was probably first designated as BD-07 4003 and added to a cataloguethat was originally published in 1863 byFriedrich Wilhelm August Argelander

(1799-1875) on the position and brightness of 324,198 stars between +90 and -2 declination that were measured over 11 years from Bonn, Germany with hisassistants Eduard Schnfeld (1828-1891) and Aldalbert Krger (1832-1896).This catalogue became famous as theBonner Durchmusterung("Bonn Survey")and is typically abbreviated as BD. It was later expanded and extended duringthe early 20th Century with theCordoba(observed from Argentina) then theCape Photographic Durchmusterung(observed from South Africa).
http://www.jenam2009.eu/http://www.jenam2009.eu/http://www.solstation.com/planets/water-worlds.htmhttp://www.solstation.com/planets/water-worlds.htmhttp://www.solstation.com/planets/water-worlds.htmhttp://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://www.solstation.com/planets/super-earths.htmhttp://www.solstation.com/planets/super-earths.htmhttp://www.nasa.gov/topics/universe/features/gliese_581_feature.htmlhttp://www.nasa.gov/topics/universe/features/gliese_581_feature.htmlhttp://www.nasa.gov/topics/universe/features/gliese_581_feature.htmlhttp://carnegiescience.edu/news/potentially_habitable_planet_discoveredhttp://carnegiescience.edu/news/potentially_habitable_planet_discoveredhttp://carnegiescience.edu/news/potentially_habitable_planet_discoveredhttp://news.ucsc.edu/2010/09/planet.htmlhttp://news.ucsc.edu/2010/09/planet.htmlhttp://news.ucsc.edu/2010/09/planet.htmlhttp://www.nsf.gov/news/news_videos.jsp?cntn_id=117765&media_id=68454&org=NSFhttp://www.nsf.gov/news/news_videos.jsp?cntn_id=117765&media_id=68454&org=NSFhttp://www.nsf.gov/news/news_videos.jsp?cntn_id=117765&media_id=68454&org=NSFhttp://planetary.org/news/2010/1006_Billions_and_Billions_Discovery_of.htmlhttp://planetary.org/news/2010/1006_Billions_and_Billions_Discovery_of.htmlhttp://planetary.org/news/2010/1006_Billions_and_Billions_Discovery_of.htmlhttp://planetary.org/news/2010/1006_Billions_and_Billions_Discovery_of.htmlhttp://www.newscientist.com/article/dn19519-found-first-rocky-exoplanet-that-could-host-life.htmlhttp://www.newscientist.com/article/dn19519-found-first-rocky-exoplanet-that-could-host-life.htmlhttp://www.newscientist.com/article/dn19519-found-first-rocky-exoplanet-that-could-host-life.htmlhttp://www.newscientist.com/article/dn19519-found-first-rocky-exoplanet-that-could-host-life.htmlhttp://www.newscientist.com/article/dn19519-found-first-rocky-exoplanet-that-could-host-life.htmlhttp://www.nytimes.com/2010/09/30/science/space/30planet.htmlhttp://www.nytimes.com/2010/09/30/science/space/30planet.htmlhttp://www.nytimes.com/2010/09/30/science/space/30planet.htmlhttp://www.nytimes.com/2010/09/30/science/space/30planet.htmlhttp://apod.nasa.gov/apod/ap101001.htmlhttp://apod.nasa.gov/apod/ap101001.htmlhttp://apod.nasa.gov/apod/ap101001.htmlhttp://apod.nasa.gov/apod/ap101001.htmlhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.unige.ch/sciences/astro/an/http://www.unige.ch/sciences/astro/an/http://www.unige.ch/sciences/astro/an/http://obswww.unige.ch/Instruments/harps/http://obswww.unige.ch/Instruments/harps/http://obswww.unige.ch/Instruments/harps/http://iaus276.oato.inaf.it/IAUS_276/Program/index.htmlhttp://iaus276.oato.inaf.it/IAUS_276/Program/index.htmlhttp://iaus276.oato.inaf.it/IAUS_276/Program/index.htmlhttp://www.solstation.com/stars/gl581.htm#planet-ghttp://www.solstation.com/stars/gl581.htm#planet-fhttp://www.solstation.com/stars/gl581.htm#planet-fhttp://www.astrobio.net/exclusive/3647/doubt-cast-on-existence-of-habitable-alien-worldhttp://www.astrobio.net/exclusive/3647/doubt-cast-on-existence-of-habitable-alien-worldhttp://www.astrobio.net/exclusive/3647/doubt-cast-on-existence-of-habitable-alien-worldhttp://www.astrobio.net/exclusive/3647/doubt-cast-on-existence-of-habitable-alien-worldhttp://www.astrobio.net/exclusive/3647/doubt-cast-on-existence-of-habitable-alien-worldhttp://www.newscientist.com/article/dn19586-first-lifefriendly-exoplanet-may-not-exist.htmlhttp://www.newscientist.com/article/dn19586-first-lifefriendly-exoplanet-may-not-exist.htmlhttp://www.newscientist.com/article/dn19586-first-lifefriendly-exoplanet-may-not-exist.htmlhttp://www.newscientist.com/article/dn19586-first-lifefriendly-exoplanet-may-not-exist.htmlhttp://www.newscientist.com/article/dn19586-first-lifefriendly-exoplanet-may-not-exist.htmlhttp://www.newscientist.com/article/dn19586-first-lifefriendly-exoplanet-may-not-exist.htmlmailto:[email protected]:[email protected]:[email protected]://extrasolar.spaceart.org/extraso3.htmlhttp://extrasolar.spaceart.org/extraso3.htmlhttp://www.solstation.com/stars/gl581g2.jpghttp://www.solstation.com/stars/gl581g2.jpghttp://www.solstation.com/stars/gl581g3.jpghttp://www.solstation.com/stars/gl581g3.jpghttp://www.nasa.gov/topics/universe/features/Gliese_581.htmlhttp://www.nasa.gov/topics/universe/features/Gliese_581.htmlhttp://www.nasa.gov/topics/universe/features/Gliese_581.htmlhttp://www.solstation.com/planets/super-earths.htmhttp://www.solstation.com/planets/super-earths.htmhttp://www.solstation.com/planets/super-earths.htmhttp://www.nasa.gov/topics/universe/features/gliese_581_feature.htmlhttp://www.nasa.gov/topics/universe/features/gliese_581_feature.htmlhttp://www.nasa.gov/topics/universe/features/gliese_581_feature.htmlhttp://www.surveyor.in-berlin.de/himmel/Bios/Argelander-e.htmlhttp://www.surveyor.in-berlin.de/himmel/Bios/Argelander-e.htmlhttp://www.surveyor.in-berlin.de/himmel/Bios/Argelander-e.htmlhttp://cdsweb.u-strasbg.fr/cgi-bin/Cat?I/122http://cdsweb.u-strasbg.fr/cgi-bin/Cat?I/122http://cdsweb.u-strasbg.fr/cgi-bin/Cat?I/122http://cdsweb.u-strasbg.fr/cgi-bin/Cat?I/114http://cdsweb.u-strasbg.fr/cgi-bin/Cat?I/114http://cdsweb.u-strasbg.fr/cgi-bin/Cat?I/114http://cdsweb.u-strasbg.fr/cgi-bin/Cat?I/108http://cdsweb.u-strasbg.fr/cgi-bin/Cat?I/108http://www.solstation.com/stars/gl581g2.jpghttp://cdsweb.u-strasbg.fr/cgi-bin/Cat?I/108http://cdsweb.u-strasbg.fr/cgi-bin/Cat?I/114http://cdsweb.u-strasbg.fr/cgi-bin/Cat?I/122http://www.surveyor.in-berlin.de/himmel/Bios/Argelander-e.htmlhttp://www.nasa.gov/topics/universe/features/gliese_581_feature.htmlhttp://www.solstation.com/planets/super-earths.htmhttp://www.nasa.gov/topics/universe/features/Gliese_581.htmlhttp://www.solstation.com/stars/gl581g3.jpghttp://www.solstation.com/stars/gl581g2.jpghttp://extrasolar.spaceart.org/extraso3.htmlmailto:[email protected]://www.newscientist.com/article/dn19586-first-lifefriendly-exoplanet-may-not-exist.htmlhttp://www.newscientist.com/article/dn19586-first-lifefriendly-exoplanet-may-not-exist.htmlhttp://www.astrobio.net/exclusive/3647/doubt-cast-on-existence-of-habitable-alien-worldhttp://www.solstation.com/stars/gl581.htm#planet-fhttp://www.solstation.com/stars/gl581.htm#planet-ghttp://iaus276.oato.inaf.it/IAUS_276/Program/index.htmlhttp://obswww.unige.ch/Instruments/harps/http://www.unige.ch/sciences/astro/an/http://www.ucolick.org/~vogt/ms_press-1.pdfhttp://apod.nasa.gov/apod/ap101001.htmlhttp://apod.nasa.gov/apod/ap101001.htmlhttp://www.nytimes.com/2010/09/30/science/space/30planet.htmlhttp://www.newscientist.com/article/dn19519-found-first-rocky-exoplanet-that-could-host-life.htmlhttp://planetary.org/news/2010/1006_Billions_and_Billions_Discovery_of.htmlhttp://planetary.org/news/2010/1006_Billions_and_Billions_Discovery_of.htmlhttp://www.nsf.gov/news/news_videos.jsp?cntn_id=117765&media_id=68454&org=NSFhttp://news.ucsc.edu/2010/09/planet.htmlhttp://carnegiescience.edu/news/potentially_habitable_planet_discoveredhttp://www.nasa.gov/topics/universe/features/gliese_581_feature.htmlhttp://www.solstation.com/planets/super-earths.htmhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://www.solstation.com/planets/water-worlds.htmhttp://www.jenam2009.eu/


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Its high proper motion was probably discovered photographically, and it wasdesignated as Wolf 562 byMax (Maximilian Franz Joseph Cornelius) Wolf(1863-1932). Wolf was a pioneer of astrophotography who discovered hundreds ofvariable stars and asteroids, and about 5,000 nebulae by analyzing photographicplates and developing the "dry plate" in 1880 and the "blink comparator" in 1900

with the Carl Zeiss optics company in Jena, Germany. Today, many astronomersrefer to this star by its earliest designation as Gl 581 in the first Gliese Catalogueof Nearby Stars (CNS, nowARICNS database)ofWilhelm Gliese(1915-93), whowas a longtime astronomer at theAstronomiches Rechen-Institut at Heidelberg(even when it was at Berlin).

---------------------------------------------- [Guide]-- [Larger] ----------------------------------------------

Orbita

l

Distan

ce(a=AU

s)

Orbita

l

Period(P=day

s)

Orbit

al

Eccen

.(e)

Orbit

al

Inclin

.(i=)

Mass(Earth

s)

Diamet

er(Earths)

Surfa

ce

Gravi

ty(g)

Low-

Hi.

Tem

p.(F)

Low-

Hi.

Tem

p.(C)

Avg.Su

r.

Temp.(K)

Avg.Eq

ui.

Temp.(K)

Glies

e 5810.0 ... ... ...

102,0

0032 ... ... ... ... ...

Plan

et

"e"

0.0285 3.15 ~0 40-851.7-3.1

>1 ... hot hot hot 420

Plan

et

"b"

0.0406 5.37 ~0 40-8515.6-30.4

>4? ... hot hot =>647 >320

Plan

et

"c"

0.0730 12.9 ~0 40-85 =>5.6 =>1.5 1.3-2 => => =>647 ~320

Inner

H.Z.

Edge

?

0.11? 25.2 0.0 40-85 ... ... ... ... ... 288 242-261+

209-228
http://www.phys-astro.sonoma.edu/BruceMedalists/Wolf/index.htmlhttp://www.phys-astro.sonoma.edu/BruceMedalists/Wolf/index.htmlhttp://www.phys-astro.sonoma.edu/BruceMedalists/Wolf/index.htmlhttp://www.ari.uni-heidelberg.de/aricns/http://www.ari.uni-heidelberg.de/aricns/http://www.ari.uni-heidelberg.de/aricns/http://www.solstation.com/stars/gliese-w.htmhttp://www.solstation.com/stars/gliese-w.htmhttp://www.solstation.com/stars/gliese-w.htmhttp://www.ari.uni-heidelberg.de/index.eng.htmhttp://www.ari.uni-heidelberg.de/index.eng.htmhttp://www.ari.uni-heidelberg.de/index.eng.htmhttp://www.solstation.com/o-guide.htmhttp://www.solstation.com/o-guide.htmhttp://www.solstation.com/o-guide.htmhttp://www.solstation.com/orbits/gl581sys.htmhttp://www.solstation.com/orbits/gl581sys.htmhttp://www.solstation.com/orbits/gl581sys.htmhttp://www.solstation.com/stars/gl581.htm#gl581http://www.solstation.com/stars/gl581.htm#gl581http://www.solstation.com/stars/gl581.htm#planet-ehttp://www.solstation.com/stars/gl581.htm#planet-ehttp://www.solstation.com/stars/gl581.htm#planet-ehttp://www.solstation.com/stars/gl581.htm#planet-bhttp://www.solstation.com/stars/gl581.htm#planet-bhttp://www.solstation.com/stars/gl581.htm#planet-bhttp://www.solstation.com/stars/gl581.htm#planet-chttp://www.solstation.com/stars/gl581.htm#planet-chttp://www.solstation.com/stars/gl581.htm#planet-chttp://www.solstation.com/stars/gl581.htm#chzhttp://www.solstation.com/stars/gl581.htm#chzhttp://www.solstation.com/stars/gl581.htm#chzhttp://www.solstation.com/stars/gl581.htm#chzhttp://www.solstation.com/stars/gl581.htm#chzhttp://www.solstation.com/stars/gl581.htm#chzhttp://www.solstation.com/stars/gl581.htm#planet-ghttp://www.solstation.com/stars/gl581.htm#planet-ghttp://www.solstation.com/stars/gl581.htm#planet-ghttp://www.solstation.com/stars/gl581.htm#planet-ghttp://www.solstation.com/stars/gl581.htm#planet-ghttp://www.solstation.com/stars/gl581.htm#planet-ghttp://www.solstation.com/stars/gl581.htm#chzhttp://www.solstation.com/stars/gl581.htm#chzhttp://www.solstation.com/stars/gl581.htm#chzhttp://www.solstation.com/stars/gl581.htm#chzhttp://www.solstation.com/stars/gl581.htm#chzhttp://www.solstation.com/stars/gl581.htm#planet-chttp://www.solstation.com/stars/gl581.htm#planet-chttp://www.solstation.com/stars/gl581.htm#planet-chttp://www.solstation.com/stars/gl581.htm#planet-bhttp://www.solstation.com/stars/gl581.htm#planet-bhttp://www.solstation.com/stars/gl581.htm#planet-bhttp://www.solstation.com/stars/gl581.htm#planet-ehttp://www.solstation.com/stars/gl581.htm#planet-ehttp://www.solstation.com/stars/gl581.htm#planet-ehttp://www.solstation.com/stars/gl581.htm#gl581http://www.solstation.com/stars/gl581.htm#gl581http://www.solstation.com/orbits/gl581sys.htmhttp://www.solstation.com/o-guide.htmhttp://www.ari.uni-heidelberg.de/index.eng.htmhttp://www.solstation.com/stars/gliese-w.htmhttp://www.ari.uni-heidelberg.de/aricns/http://www.phys-astro.sonoma.edu/BruceMedalists/Wolf/index.html


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Plan

et

"d"

0.218 66.9 ~0 40-855.6-8.4

=>1.5 =>1.8 cold? cold? >273 203-233

Oute

r

H.Z.Edge

?

0.28? 87.8 0.0 40-85 ... ... ... ... ... 1.5 ... frigid frigid


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percent, which suggests that the star is probably several billions years old(more). Gliese 581 has been previously classified as a variable star with thedesignation "HO Librae" and NSV 7023, but "its short-term variability to be atmost 0.006 magnitudes" (Vogt et al, 2010;andEdward W. Weis, 1994). Someother useful star catalogue designations include: HO Lib, Gl 581, Hip 74995, BD-

07 4003, G 151-46, G 152-9, LHS 394, LTT 6112, LPM 564, LFT 1195, Vys/MCC159, and Wolf 562.

Habitable Zone

ESO,unknow n art is t

Largeri l lustrat ion.

As a red dw arf star wi th

sub-Solar

mass , diameter, and

luminosi ty ,

Gliese 581 has a

habitable zone

that is much narrower

and closer

in orb i ta l d is tance when

compared

to theSolar System,so

that

potentia l ly h abitable,planetary

candidate "g " is l ike ly to

have

synchrono us rota tion(more).

A planetary object in space without an internal heat source will heat up orcool off until its surface reaches a thermal "equilibrium temperature,"where it emits exactly as much thermal energy as it receives from its host

star(s). A relatively massive planet (like Venus, Earth, or largersuper-Earth)with a dense atmosphere and sufficient amounts of gases that block re-radiation of infrared heat back into space, however, will warm further fromagreenhouse effect.With such considerations in mind, some astronomershave calculated the habitable zone around Gliese 581 for representativesuper-Earths to be as wide as between around 0.11 and 0.28 AUs from thestar, but the actual inner and out limits depend on the presence of a denseatmosphere rich in water, carbon dioxide, and cloud cover (especially of
http://www.astronomy.com/asy/default.aspx?c=a&id=5619http://www.astronomy.com/asy/default.aspx?c=a&id=5619http://www.astronomy.com/asy/default.aspx?c=a&id=5619http://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://adsabs.harvard.edu/abs/1994AJ....107.1135Whttp://adsabs.harvard.edu/abs/1994AJ....107.1135Whttp://adsabs.harvard.edu/abs/1994AJ....107.1135Whttp://www.eso.org/http://www.eso.org/http://www.eso.org/http://www.solstation.com/stars/gl581hz2.jpghttp://www.solstation.com/stars/gl581hz2.jpghttp://www.solstation.com/stars/sol-sum.htmhttp://www.solstation.com/stars/sol-sum.htmhttp://www.solstation.com/stars/sol-sum.htmhttp://en.wikipedia.org/wiki/Synchronous_rotationhttp://en.wikipedia.org/wiki/Synchronous_rotationhttp://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://lasp.colorado.edu/~bagenal/3720/CLASS6/6EquilibriumTemp.htmlhttp://lasp.colorado.edu/~bagenal/3720/CLASS6/6EquilibriumTemp.htmlhttp://www.solstation.com/planets/super-earths.htmhttp://www.solstation.com/planets/super-earths.htmhttp://www.solstation.com/planets/super-earths.htmhttp://www.epa.gov/climatechange/kids/greenhouse.htmlhttp://www.epa.gov/climatechange/kids/greenhouse.htmlhttp://www.epa.gov/climatechange/kids/greenhouse.htmlhttp://www.solstation.com/stars/gl581hz2.jpghttp://www.epa.gov/climatechange/kids/greenhouse.htmlhttp://www.solstation.com/planets/super-earths.htmhttp://lasp.colorado.edu/~bagenal/3720/CLASS6/6EquilibriumTemp.htmlhttp://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://en.wikipedia.org/wiki/Synchronous_rotationhttp://www.solstation.com/stars/sol-sum.htmhttp://www.solstation.com/stars/gl581hz2.jpghttp://www.eso.org/http://adsabs.harvard.edu/abs/1994AJ....107.1135Whttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.astronomy.com/asy/default.aspx?c=a&id=5619


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carbon dioxide), among other considerations (more discussion inVogt etal, 2010;Selsis et al, 2008;von Bloh et al, 2008;andTarter et al, 2007).

Planetary System

As of September 29, 2010, Gliese 581 was believed by some astronomers tohost at least six planets between the size ofEarthandNeptune,with oneplanetary candidate ("g") orbiting the star wholely within itshabitable zonewhose existence has not been confirmed.

ESO,unknown artist

Largerillustration.

Fourth to be discovered,innermostplanetary candidate "e"with twoto three times Earth'smass wasfirst detected in 2009(more).

Planet " e"- On April 21, 2009, a team of astronomers at the2009 EuropeanWeek of Astronomy and Space Scienceconference announced the discovery ofplanetary candidate "e" with a minimum mass initially estimated to be around 1.9(and a maximum of 3.1) Earth-masses in an innermost orbit, along with neworbital analysis suggesting that planetary candidate "d" may orbit Gliese 581 inits so-called habitable zone (ESOpress release;Mayor et al, 2009;Selsis et al,2008); andvon Bloh et al, 2008.The fourth object to be discovered around

Gliese 581, planet e is now thought to have at least 1.7 Earth-masses (or0.0053 Jupiter-masses). It revolves around Gliese 581 -- outside of planetb's orbit -- at an average distance of 0.0285 AU, in a roughly circular orbit(e~0) which it completes in 3.14867 +/- 0.00039 days (Vogt et al, 2010;andMayor et al, 2009).
http://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://adsabs.harvard.edu/abs/2007A%26A...476.1373Shttp://adsabs.harvard.edu/abs/2007A%26A...476.1373Shttp://adsabs.harvard.edu/abs/2007A%26A...476.1373Shttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://www.funkyscience.net/documents/mstar.pdfhttp://www.funkyscience.net/documents/mstar.pdfhttp://www.funkyscience.net/documents/mstar.pdfhttp://www.solstation.com/stars/earth.htmhttp://www.solstation.com/stars/earth.htmhttp://www.solstation.com/stars/earth.htmhttp://www.solstation.com/stars/neptune.htmhttp://www.solstation.com/stars/neptune.htmhttp://www.solstation.com/stars/neptune.htmhttp://www.pbs.org/lifebeyondearth/alone/habitable.htmlhttp://www.pbs.org/lifebeyondearth/alone/habitable.htmlhttp://www.pbs.org/lifebeyondearth/alone/habitable.htmlhttp://www.eso.org/http://www.eso.org/http://www.eso.org/http://www.solstation.com/stars/gl581e2.jpghttp://www.solstation.com/stars/gl581e2.jpghttp://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://www.jenam2009.eu/http://www.jenam2009.eu/http://www.jenam2009.eu/http://www.jenam2009.eu/http://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://www.aanda.org/index.php?option=article&access=standard&Itemid=129&url=/articles/aa/abs/2007/48/aa8091-07/aa8091-07.htmlhttp://www.aanda.org/index.php?option=article&access=standard&Itemid=129&url=/articles/aa/abs/2007/48/aa8091-07/aa8091-07.htmlhttp://www.aanda.org/index.php?option=article&access=standard&Itemid=129&url=/articles/aa/abs/2007/48/aa8091-07/aa8091-07.htmlhttp://www.aanda.org/index.php?option=article&access=standard&Itemid=129&url=/articles/aa/abs/2007/48/aa8091-07/aa8091-07.htmlhttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://www.solstation.com/stars/gl581e2.jpghttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://www.aanda.org/index.php?option=article&access=standard&Itemid=129&url=/articles/aa/abs/2007/48/aa8091-07/aa8091-07.htmlhttp://www.aanda.org/index.php?option=article&access=standard&Itemid=129&url=/articles/aa/abs/2007/48/aa8091-07/aa8091-07.htmlhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://www.jenam2009.eu/http://www.jenam2009.eu/http://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://www.solstation.com/stars/gl581e2.jpghttp://www.eso.org/http://www.pbs.org/lifebeyondearth/alone/habitable.htmlhttp://www.solstation.com/stars/neptune.htmhttp://www.solstation.com/stars/earth.htmhttp://www.funkyscience.net/documents/mstar.pdfhttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://adsabs.harvard.edu/abs/2007A%26A...476.1373Shttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdf


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JPL,NASA

Largerimage.

It is not yet known whetherplanetary candidate "b" isrocky or gaseous -- likeNeptune.

Planet "b "- On November 30, 2005, a team of French and Swiss astronomersannounced the discovery of aNeptune-class planet in a very close "torch" orbitaround this star using theHARPS spectrographon theEuropean SouthernObservatory's3.6-meter telescope at La Silla,Chile (ESOpress release)andBonfils et al, 2005,inpdf). Initially estimated with at least 16.6 Earth-masses,the mass of planet "b" has been more recently updated to at least 15.6

times (maximum of 30.4) that of the Earth. With a semi-major axis of 0.041AUs (around 6 million kilometers), it orbits so close to its host star that itsorbital period lasts only 5.36841 +/- 0.00026 days, in a highly circular orbit(e~0) (Vogt et al, 2010;Mayor et al, 2009;andUdry et al, 2007). As a result,the planet must be very hot, with anequilibrium temperatureat around 297Fahrenheit (147 Celsius or 420 kelvins).

ESO,unknown artist

Largerillustration.

On Planet "c," water is unlikely to exist on itsday-side surface (except as lakes or seas onits colder dark side opposite the star) undera likely dense atmosphere (more).

Planet "c "-On April 25, 2007, a teamof Swiss, French and Portuguese astronomers (again using theHARPS

spectrographon theEuropean Southern Observatory's3.6-meter telescope)announced the discovery of two additional lower-mass planets in this system,including the most Earth-like planet found outside the Solar System to date (ESOnews release;Udry et al, 2007;Observatoire de Genve's web page onGl 581;andAstronomy Picture of the Day). The more Earth-like planet "c" has at least5.6 (maximum of 10.4) Earth-masses and an estimated diameter of at least
http://www.jpl.nasa.gov/http://www.jpl.nasa.gov/http://www.nasa.gov/http://www.nasa.gov/http://www.nasa.gov/http://www.solstation.com/stars2/comp2enj.jpghttp://www.solstation.com/stars2/comp2enj.jpghttp://www.solstation.com/stars/neptune.htmhttp://www.solstation.com/stars/neptune.htmhttp://www.solstation.com/stars/neptune.htmhttp://www.solstation.com/stars/neptune.htmhttp://www.solstation.com/stars/neptune.htmhttp://www.ls.eso.org/lasilla/sciops/3p6/harps/index.htmlhttp://www.ls.eso.org/lasilla/sciops/3p6/harps/index.htmlhttp://www.ls.eso.org/lasilla/sciops/3p6/harps/index.htmlhttp://www.eso.org/http://www.eso.org/http://www.eso.org/http://www.eso.org/http://www.ls.eso.org/index.htmlhttp://www.ls.eso.org/index.htmlhttp://www.ls.eso.org/index.htmlhttp://www.eso.org/outreach/press-rel/pr-2005/pr-30-05.htmlhttp://www.eso.org/outreach/press-rel/pr-2005/pr-30-05.htmlhttp://www.eso.org/outreach/press-rel/pr-2005/pr-30-05.htmlhttp://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2005A%26A...443L..15B&db_key=AST&data_type=HTML&format=&high=438efdb55325468http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2005A%26A...443L..15B&db_key=AST&data_type=HTML&format=&high=438efdb55325468http://www.edpsciences.org/articles/aa/pdf/2005/45/aahh223.pdfhttp://www.edpsciences.org/articles/aa/pdf/2005/45/aahh223.pdfhttp://www.edpsciences.org/articles/aa/pdf/2005/45/aahh223.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://obswww.unige.ch/~udry/udry_preprint.pdfhttp://obswww.unige.ch/~udry/udry_preprint.pdfhttp://obswww.unige.ch/~udry/udry_preprint.pdfhttp://lasp.colorado.edu/~bagenal/3720/CLASS6/6EquilibriumTemp.htmlhttp://lasp.colorado.edu/~bagenal/3720/CLASS6/6EquilibriumTemp.htmlhttp://lasp.colorado.edu/~bagenal/3720/CLASS6/6EquilibriumTemp.htmlhttp://www.eso.org/http://www.eso.org/http://www.eso.org/http://www.solstation.com/stars/gl581c2.jpghttp://www.solstation.com/stars/gl581c2.jpghttp://www.eso.org/outreach/press-rel/pr-2007/pr-22-07.htmlhttp://www.eso.org/outreach/press-rel/pr-2007/pr-22-07.htmlhttp://www.eso.org/outreach/press-rel/pr-2007/pr-22-07.htmlhttp://www.ls.eso.org/lasilla/sciops/3p6/harps/index.htmlhttp://www.ls.eso.org/lasilla/sciops/3p6/harps/index.htmlhttp://www.ls.eso.org/lasilla/sciops/3p6/harps/index.htmlhttp://www.ls.eso.org/lasilla/sciops/3p6/harps/index.htmlhttp://www.eso.org/http://www.eso.org/http://www.eso.org/http://www.ls.eso.org/index.htmlhttp://www.ls.eso.org/index.htmlhttp://www.ls.eso.org/index.htmlhttp://www.eso.org/outreach/press-rel/pr-2007/pr-22-07.htmlhttp://www.eso.org/outreach/press-rel/pr-2007/pr-22-07.htmlhttp://obswww.unige.ch/~udry/udry_preprint.pdfhttp://obswww.unige.ch/~udry/udry_preprint.pdfhttp://obswww.unige.ch/~udry/udry_preprint.pdfhttp://obswww.unige.ch/exoplanets/gl581.htmlhttp://obswww.unige.ch/exoplanets/gl581.htmlhttp://obswww.unige.ch/exoplanets/gl581.htmlhttp://antwrp.gsfc.nasa.gov/apod/ap070426.htmlhttp://antwrp.gsfc.nasa.gov/apod/ap070426.htmlhttp://antwrp.gsfc.nasa.gov/apod/ap070426.htmlhttp://www.solstation.com/stars/gl581c2.jpghttp://www.solstation.com/stars2/comp2enj.jpghttp://www.solstation.com/stars/gl581c2.jpghttp://www.solstation.com/stars2/comp2enj.jpghttp://antwrp.gsfc.nasa.gov/apod/ap070426.htmlhttp://obswww.unige.ch/exoplanets/gl581.htmlhttp://obswww.unige.ch/~udry/udry_preprint.pdfhttp://www.eso.org/outreach/press-rel/pr-2007/pr-22-07.htmlhttp://www.ls.eso.org/index.htmlhttp://www.eso.org/http://www.ls.eso.org/lasilla/sciops/3p6/harps/index.htmlhttp://www.ls.eso.org/lasilla/sciops/3p6/harps/index.htmlhttp://www.eso.org/outreach/press-rel/pr-2007/pr-22-07.htmlhttp://www.solstation.com/stars/gl581c2.jpghttp://www.eso.org/http://lasp.colorado.edu/~bagenal/3720/CLASS6/6EquilibriumTemp.htmlhttp://obswww.unige.ch/~udry/udry_preprint.pdfhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.edpsciences.org/articles/aa/pdf/2005/45/aahh223.pdfhttp://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2005A%26A...443L..15B&db_key=AST&data_type=HTML&format=&high=438efdb55325468http://www.eso.org/outreach/press-rel/pr-2005/pr-30-05.htmlhttp://www.ls.eso.org/index.htmlhttp://www.eso.org/http://www.eso.org/http://www.ls.eso.org/lasilla/sciops/3p6/harps/index.htmlhttp://www.solstation.com/stars/neptune.htmhttp://www.solstation.com/stars/neptune.htmhttp://www.solstation.com/stars2/comp2enj.jpghttp://www.nasa.gov/http://www.jpl.nasa.gov/


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1.5 times Earth's if it is rocky, larger if it is composed of mostly ice. Itmoves around Gliese 581 -- outside of planet b's orbit -- at an averagedistance of 0.07 AU, in a highly circular orbit (possibly not as eccentric ase= 0.17 0.07) which it completes in 12.9191 +/- 0.0058 days (Vogt et al,2010;andMayor et al, 2009). Based on its minimum mass and a range of

predicted radii, the surface gravity of planet c may lie between 1.3 and 2 g(Selsis et al, 2008;Sotin et al, 2007; and Valencia et al, 2007).

Planet c was initially calculated to orbit Gliese 581 near the hot, inner edgeof the red dwarf's relative narrow and very closehabitable zone.It wasthought to have a equilibrium temperature between -3 and more than 40Celsius (27 and more than 104 Fahrenheit) with water on its surface,depending on whether the planet has a Venus- or an Earth-like albedo(Udry et al, 2007). Subsequent models indicated, however, that such amassive planet is likely have a dense atmosphere with a gas compositionthat should undergo a Venus-like runaway greenhouse effect, which should

boil off all surface water (Vogt et al, 2010;Selsis et al, 2008;andvon Blohet al, 2008), although others have suggested that surface lakes or seascould be possible on the colder, perpetually dark side of planet c (see anillustration of such water features on planet c byLynette Cook). (Illustrationsof another artist's vision of day- and night-side surfaces of planet c due to tidallylocked,synchronous rotationaround host star Gliese 581 are available fromKaren WehrsteinandAstronomy Picture of the Day.)

ESO,unknown artist

Animationstill.

Planetary candidate "d" orbits justwithinthe outer edge of Gliese 581'shabitablezoneand so may have liquid surfacewater in adeep global ocean(more).

Planet "d "- On April 21, 2009, a team of astronomers at the2009 EuropeanWeek of Astronomy and Space Scienceconference announced revised orbitalanalysis suggesting that planetary candidate "d" may orbit Gliese 581 in its so-called habitable zone (ESOpress release;Mayor et al, 2009;von Bloh et al,2008;andSelssis et al, 2007). Planet "d" is now estimated to have between5.6 and 8.4 Earth-masses. It revolves around Gliese 581 -- outside of planetb's orbit -- at an average distance of 0.218 AU, probably in a circular orbit(rather than a previously calculated eccentric orbit with e= 0.38 +/- 0.09)
http://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://adsabs.harvard.edu/abs/2007A%26A...476.1373Shttp://adsabs.harvard.edu/abs/2007A%26A...476.1373Shttp://adsabs.harvard.edu/abs/2007A%26A...476.1373Shttp://www.funkyscience.net/documents/mstar.pdfhttp://www.funkyscience.net/documents/mstar.pdfhttp://www.funkyscience.net/documents/mstar.pdfhttp://obswww.unige.ch/~udry/udry_preprint.pdfhttp://obswww.unige.ch/~udry/udry_preprint.pdfhttp://obswww.unige.ch/~udry/udry_preprint.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://adsabs.harvard.edu/abs/2007A%26A...476.1373Shttp://adsabs.harvard.edu/abs/2007A%26A...476.1373Shttp://adsabs.harvard.edu/abs/2007A%26A...476.1373Shttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://extrasolar.spaceart.org/cgi-bin/image2.cgi?filename=gliese581c.jpg&title=Gliese%20581%20cmailto:[email protected]:[email protected]:[email protected]://en.wikipedia.org/wiki/Synchronous_rotationhttp://en.wikipedia.org/wiki/Synchronous_rotationhttp://en.wikipedia.org/wiki/Synchronous_rotationhttp://www.artofkaren.blogspot.com/http://www.artofkaren.blogspot.com/http://antwrp.gsfc.nasa.gov/apod/ap070502.htmlhttp://antwrp.gsfc.nasa.gov/apod/ap070502.htmlhttp://antwrp.gsfc.nasa.gov/apod/ap070502.htmlhttp://www.eso.org/http://www.eso.org/http://www.eso.org/http://www.eso.org/gallery/v/Videos/VNRs/vid-15e-09_P_FLASH.flv.htmlhttp://www.eso.org/gallery/v/Videos/VNRs/vid-15e-09_P_FLASH.flv.htmlhttp://www.pbs.org/lifebeyondearth/alone/habitable.htmlhttp://www.pbs.org/lifebeyondearth/alone/habitable.htmlhttp://www.pbs.org/lifebeyondearth/alone/habitable.htmlhttp://www.solstation.com/planets/water-worlds.htmhttp://www.solstation.com/planets/water-worlds.htmhttp://www.solstation.com/planets/water-worlds.htmhttp://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://www.jenam2009.eu/http://www.jenam2009.eu/http://www.jenam2009.eu/http://www.jenam2009.eu/http://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://www.aanda.org/index.php?option=article&access=standard&Itemid=129&url=/articles/aa/abs/2007/48/aa8091-07/aa8091-07.htmlhttp://www.aanda.org/index.php?option=article&access=standard&Itemid=129&url=/articles/aa/abs/2007/48/aa8091-07/aa8091-07.htmlhttp://www.aanda.org/index.php?option=article&access=standard&Itemid=129&url=/articles/aa/abs/2007/48/aa8091-07/aa8091-07.htmlhttp://www.eso.org/gallery/v/Videos/VNRs/vid-15e-09_P_FLASH.flv.htmlhttp://www.aanda.org/index.php?option=article&access=standard&Itemid=129&url=/articles/aa/abs/2007/48/aa8091-07/aa8091-07.htmlhttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://www.jenam2009.eu/http://www.jenam2009.eu/http://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://www.solstation.com/planets/water-worlds.htmhttp://www.pbs.org/lifebeyondearth/alone/habitable.htmlhttp://www.pbs.org/lifebeyondearth/alone/habitable.htmlhttp://www.eso.org/gallery/v/Videos/VNRs/vid-15e-09_P_FLASH.flv.htmlhttp://www.eso.org/http://antwrp.gsfc.nasa.gov/apod/ap070502.htmlhttp://www.artofkaren.blogspot.com/http://en.wikipedia.org/wiki/Synchronous_rotationmailto:[email protected]://extrasolar.spaceart.org/cgi-bin/image2.cgi?filename=gliese581c.jpg&title=Gliese%20581%20chttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://adsabs.harvard.edu/abs/2007A%26A...476.1373Shttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://obswww.unige.ch/~udry/udry_preprint.pdfhttp://www.funkyscience.net/documents/mstar.pdfhttp://adsabs.harvard.edu/abs/2007A%26A...476.1373Shttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdf


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which it completes in 66.87 (+/- 0.13) days, not quite a fifth of an Earth year.Although it was once thought possible that this detection was actuallycaused by a large star spot, its discoverers now believe that the host star istoo inactive for this possibility to be likely (Vogt et al, 2010;Mayor et al,2009;andUdry et al, 2007).Subsequent calculations suggest that a

greenhouse effect under the right atmospheric conditions may make it possiblefor liquid water to persist on its surface despite its tidally locked,synchronousrotationaround Gliese 581 (von Bloh et al, 2008).

Orbiting near the outer edge of Gliese 581's habitable zone at an orbitaldistance of just under 0.22 AU, planet d receives "35% less stellar energythanMarsand is probably locked in tidal resonance, with extremely lowinsolation at the poles and possibly a permanent night side" and so couldbe subject to "global glaciation and / or atmospheric collapse"(Wordsworth et al, 2011). The planet would have a maximum equilibriumtemperature of only around -94 Fahrenheit (-70 Celsius and 203 kelvins). if

it had aBond albedo(the fraction of power at all wavelengths re-radiatedback into space) of 0, or -40 F (-40 C or 233 K) under more optimisticassumptions (Olaf Stampf, Der Spiegel, October 8, 2010;Kaltenegger et al,2010;Vogt et al, 2010), which would be too cold to maintain liquid water onits surface. As planet d is calculated to have between 5.6 to 8.4 Earth-mass,however, it should be tectonically active with massive volcanic eruptionsthat spew lots of carbon dioxide (CO2) and other greenhouse gases tocreate a dense envelope of air under high atmospheric pressure.

LMD,CNRS

Largeran djumbo

i l lus tra t ions (source).

Model s imula t ions sug gest

that

Gl iese 581 d can be warm

enough

to have l iqu id water on i ts

surface

i f i ts atmosphere is

suf f ic ient ly

th ick and r ich in CO2(mo re).

Models show that when atmospheric pressure rises to at least fivebar(5times Earth's atmospheric pressure at sea level), the resulting greenhouseeffect in a high-CO2atmosphere can cause temperatures to risesignificantly above freezing and thaw surface ice (Olaf Stampf, Der Spiegel,October 8, 2010;Kaltenegger et al, 2010;von Paris et al, 2010;Wordsworth
http://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://obswww.unige.ch/~udry/udry_preprint.pdfhttp://obswww.unige.ch/~udry/udry_preprint.pdfhttp://obswww.unige.ch/~udry/udry_preprint.pdfhttp://en.wikipedia.org/wiki/Synchronous_rotationhttp://en.wikipedia.org/wiki/Synchronous_rotationhttp://en.wikipedia.org/wiki/Synchronous_rotationhttp://en.wikipedia.org/wiki/Synchronous_rotationhttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://www.solstation.com/stars/mars.htmhttp://www.solstation.com/stars/mars.htmhttp://www.solstation.com/stars/mars.htmhttp://aps.arxiv.org/abs/1105.1031http://aps.arxiv.org/abs/1105.1031http://aps.arxiv.org/abs/1105.1031http://en.wikipedia.org/wiki/Bond_albedohttp://en.wikipedia.org/wiki/Bond_albedohttp://en.wikipedia.org/wiki/Bond_albedohttp://www.spiegel.de/international/zeitgeist/0,1518,721840,00.htmlhttp://www.spiegel.de/international/zeitgeist/0,1518,721840,00.htmlhttp://www.spiegel.de/international/zeitgeist/0,1518,721840,00.htmlhttp://www.spiegel.de/international/zeitgeist/0,1518,721840,00.htmlhttp://www.spiegel.de/international/zeitgeist/0,1518,721840,00.htmlhttp://adsabs.harvard.edu/abs/2010LPICo1538.5613Khttp://adsabs.harvard.edu/abs/2010LPICo1538.5613Khttp://adsabs.harvard.edu/abs/2010LPICo1538.5613Khttp://adsabs.harvard.edu/abs/2010LPICo1538.5613Khttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.lmd.jussieu.fr/http://www.lmd.jussieu.fr/http://www.lmd.jussieu.fr/http://www.cnrs.fr/index.phphttp://www.cnrs.fr/index.phphttp://www.cnrs.fr/index.phphttp://www.solstation.com/stars/gl581d2t.jpghttp://www.solstation.com/stars/gl581d2t.jpghttp://www.solstation.com/stars/gl581d3t.jpghttp://www.solstation.com/stars/gl581d3t.jpghttp://www.solstation.com/stars/gl581d3t.jpghttp://www.lmd.jussieu.fr/actualites/actualites-scientifiques/premiere-exoplanete-habitable-une-nouvelle-candidate-revelee-par-des-climatologues-du-lmdhttp://www.lmd.jussieu.fr/actualites/actualites-scientifiques/premiere-exoplanete-habitable-une-nouvelle-candidate-revelee-par-des-climatologues-du-lmdhttp://www.lmd.jussieu.fr/actualites/actualites-scientifiques/premiere-exoplanete-habitable-une-nouvelle-candidate-revelee-par-des-climatologues-du-lmdhttp://www2.cnrs.fr/en/1862.htmhttp://www2.cnrs.fr/en/1862.htmhttp://www2.cnrs.fr/en/1862.htmhttp://en.wikipedia.org/wiki/Bar_%28unit%29http://en.wikipedia.org/wiki/Bar_%28unit%29http://en.wikipedia.org/wiki/Bar_%28unit%29http://www.spiegel.de/international/zeitgeist/0,1518,721840,00.htmlhttp://www.spiegel.de/international/zeitgeist/0,1518,721840,00.htmlhttp://www.spiegel.de/international/zeitgeist/0,1518,721840,00.htmlhttp://www.spiegel.de/international/zeitgeist/0,1518,721840,00.htmlhttp://www.spiegel.de/international/zeitgeist/0,1518,721840,00.htmlhttp://www.spiegel.de/international/zeitgeist/0,1518,721840,00.htmlhttp://adsabs.harvard.edu/abs/2010LPICo1538.5613Khttp://adsabs.harvard.edu/abs/2010LPICo1538.5613Khttp://adsabs.harvard.edu/abs/2010LPICo1538.5613Khttp://arxiv.org/abs/1009.5814http://arxiv.org/abs/1009.5814http://arxiv.org/abs/1009.5814http://adsabs.harvard.edu/abs/2010arXiv1005.5098Whttp://adsabs.harvard.edu/abs/2010arXiv1005.5098Whttp://www.solstation.com/stars/gl581d2t.jpghttp://adsabs.harvard.edu/abs/2010arXiv1005.5098Whttp://arxiv.org/abs/1009.5814http://adsabs.harvard.edu/abs/2010LPICo1538.5613Khttp://www.spiegel.de/international/zeitgeist/0,1518,721840,00.htmlhttp://www.spiegel.de/international/zeitgeist/0,1518,721840,00.htmlhttp://en.wikipedia.org/wiki/Bar_%28unit%29http://www2.cnrs.fr/en/1862.htmhttp://www.lmd.jussieu.fr/actualites/actualites-scientifiques/premiere-exoplanete-habitable-une-nouvelle-candidate-revelee-par-des-climatologues-du-lmdhttp://www.solstation.com/stars/gl581d3t.jpghttp://www.solstation.com/stars/gl581d2t.jpghttp://www.cnrs.fr/index.phphttp://www.lmd.jussieu.fr/http://www.ucolick.org/~vogt/ms_press-1.pdfhttp://adsabs.harvard.edu/abs/2010LPICo1538.5613Khttp://adsabs.harvard.edu/abs/2010LPICo1538.5613Khttp://www.spiegel.de/international/zeitgeist/0,1518,721840,00.htmlhttp://en.wikipedia.org/wiki/Bond_albedohttp://aps.arxiv.org/abs/1105.1031http://www.solstation.com/stars/mars.htmhttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://en.wikipedia.org/wiki/Synchronous_rotationhttp://en.wikipedia.org/wiki/Synchronous_rotationhttp://obswww.unige.ch/~udry/udry_preprint.pdfhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://obswww.unige.ch/~udry/Gl581_preprint.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdf


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et al, 2010;Vogt et al, 2010;Selsis et al, 2008;andvon Bloh et al, 2008).Model calculations suggest that atmospheric pressure on the planet mayreach up to seven or eight bars, a level found on Earth at the bottom oflakes. If the atmosphere has more than 10 bars of CO2and and other gases(such as molecular nitrogen, or N2), however, three-dimensional climate

simulations suggest that the planet's global mean temperatures could riseabove freezing for land as well as ocean-covered surfaces (Wordsworth etal, 2011;andJon Voisey, Universe Today, May 6, 2011). Some astronomersalso believe that planet d is too massive to be made only of rock; morelikely, the planet is ice-rich (like Neptune or Uranus which agglomeratedlarge ice layers of water, ammonia, and methane) before migratng closer toGliese 581, and so its abundant ices could have been warmed enough tomelt into adeep global ocean(ESOpress release). If planet d does haverocky surfaces, its surface gravity in those areas would be around 1.8 g(2009 presentation slidesfrom Kaltenegger et al, 2010?).

Lynette Cook(Ar twork from

Extrasolar Planets - Col lection III,

used wi th permiss ion)

Largeran dju mboi l lus tra t ions.

Planetary candidate "g " is bel ieved

to be a rockysuper-Earththat orb i ts

Gl iese 581 within the red dw arf

star 's habitable zone (mo re).

Planet "g "- On September 29, 2010, a team of astronomers (includingSteven S. Vogt;R. Paul Butler;Eugenio J. Rivera;Nader Haghighipour;Gregory W. Henry;andMichael H. Williamson)announced the discovery ofa "potentially habitable," rocky super-Earth "g" orbiting within thehabitable zone, based on 11 years of radial-velocity measurements at theKeck Observatoryand similar published data from theGenevaObservatory'sHigh Accuracy Radial velocity Planetary Search(HARPS)project. Planetary candidate g is estimated to have between 3.1 and 4.3

Earth-masses and between 1.3 and 1.5 times Earth's diameter, with agreater surface gravity of around 1.1 to 1.7 g. It has an orbital period of 36.6days at an average orbital distance of 0.146 AUs. Three different teams ofastronomers have found that the dynamically stable orbits for the planetarysystem are possible only if these orbits have an inclination constrained tobetween 40 and 85 degrees and with respect to the line of sight from Earth,and so the mass of each planet must be less than around 1.4 (updated from1.6) times its estimated minimum mass, if orbital eccentricities are less
http://adsabs.harvard.edu/abs/2010arXiv1005.5098Whttp://adsabs.harvard.edu/abs/2010arXiv1005.5098Whttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://adsabs.harvard.edu/abs/2007A%26A...476.1373Shttp://adsabs.harvard.edu/abs/2007A%26A...476.1373Shttp://adsabs.harvard.edu/abs/2007A%26A...476.1373Shttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://aps.arxiv.org/abs/1105.1031http://aps.arxiv.org/abs/1105.1031http://aps.arxiv.org/abs/1105.1031http://aps.arxiv.org/abs/1105.1031http://www.universetoday.com/85474/update-on-gliese-581ds-habitability/http://www.universetoday.com/85474/update-on-gliese-581ds-habitability/http://www.universetoday.com/85474/update-on-gliese-581ds-habitability/http://www.solstation.com/planets/water-worlds.htmhttp://www.solstation.com/planets/water-worlds.htmhttp://www.solstation.com/planets/water-worlds.htmhttp://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://www.dartmouth.edu/~physics/news/colloquium.archives/kaltenegger_1_9.09.pdfhttp://www.dartmouth.edu/~physics/news/colloquium.archives/kaltenegger_1_9.09.pdfhttp://www.dartmouth.edu/~physics/news/colloquium.archives/kaltenegger_1_9.09.pdfmailto:[email protected]:[email protected]:[email protected]://extrasolar.spaceart.org/extraso3.htmlhttp://extrasolar.spaceart.org/extraso3.htmlhttp://www.solstation.com/stars/gl581g2.jpghttp://www.solstation.com/stars/gl581g2.jpghttp://www.solstation.com/stars/gl581g3.jpghttp://www.solstation.com/stars/gl581g3.jpghttp://www.nasa.gov/topics/universe/features/Gliese_581.htmlhttp://www.nasa.gov/topics/universe/features/Gliese_581.htmlhttp://www.nasa.gov/topics/universe/features/Gliese_581.htmlhttp://www.solstation.com/planets/super-earths.htmhttp://www.solstation.com/planets/super-earths.htmhttp://www.solstation.com/planets/super-earths.htmhttp://www.nasa.gov/topics/universe/features/gliese_581_feature.htmlhttp://www.nasa.gov/topics/universe/features/gliese_581_feature.htmlhttp://www.nasa.gov/topics/universe/features/gliese_581_feature.htmlhttp://www.ucolick.org/~vogt/http://www.ucolick.org/~vogt/http://www.dtm.ciw.edu/users/paul/http://www.dtm.ciw.edu/users/paul/http://www.dtm.ciw.edu/users/paul/http://www.aipuniphy.org/Profile.bme/103745/Eugenio_J_Riverahttp://www.aipuniphy.org/Profile.bme/103745/Eugenio_J_Riverahttp://www.aipuniphy.org/Profile.bme/103745/Eugenio_J_Riverahttp://www.ifa.hawaii.edu/~nader/http://www.ifa.hawaii.edu/~nader/http://www.ifa.hawaii.edu/~nader/http://schwab.tsuniv.edu/henrypage.htmlhttp://schwab.tsuniv.edu/henrypage.htmlhttp://schwab.tsuniv.edu/members.htmlhttp://schwab.tsuniv.edu/members.htmlhttp://schwab.tsuniv.edu/members.htmlhttp://www.keckobservatory.org/http://www.keckobservatory.org/http://www.unige.ch/sciences/astro/an/http://www.unige.ch/sciences/astro/an/http://www.unige.ch/sciences/astro/an/http://www.unige.ch/sciences/astro/an/http://obswww.unige.ch/Instruments/harps/http://obswww.unige.ch/Instruments/harps/http://obswww.unige.ch/Instruments/harps/http://www.solstation.com/stars/gl581g2.jpghttp://obswww.unige.ch/Instruments/harps/http://www.unige.ch/sciences/astro/an/http://www.unige.ch/sciences/astro/an/http://www.keckobservatory.org/http://schwab.tsuniv.edu/members.htmlhttp://schwab.tsuniv.edu/henrypage.htmlhttp://www.ifa.hawaii.edu/~nader/http://www.aipuniphy.org/Profile.bme/103745/Eugenio_J_Riverahttp://www.dtm.ciw.edu/users/paul/http://www.ucolick.org/~vogt/http://www.nasa.gov/topics/universe/features/gliese_581_feature.htmlhttp://www.solstation.com/planets/super-earths.htmhttp://www.nasa.gov/topics/universe/features/Gliese_581.htmlhttp://www.solstation.com/stars/gl581g3.jpghttp://www.solstation.com/stars/gl581g2.jpghttp://extrasolar.spaceart.org/extraso3.htmlmailto:[email protected]://www.dartmouth.edu/~physics/news/colloquium.archives/kaltenegger_1_9.09.pdfhttp://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.htmlhttp://www.solstation.com/planets/water-worlds.htmhttp://www.universetoday.com/85474/update-on-gliese-581ds-habitability/http://aps.arxiv.org/abs/1105.1031http://aps.arxiv.org/abs/1105.1031http://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdfhttp://adsabs.harvard.edu/abs/2007A%26A...476.1373Shttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://adsabs.harvard.edu/abs/2010arXiv1005.5098W


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than 0.2 (e


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On October 22, 2010, one of the astronomers associated with theunconfirmed discovery ofsuper-Earthplanetary candidate "g" aroundGliese 581 and a planetary scientist noted for his atmospheric modellingwork submitted a paper on their model of the planet's atmosphere, winds,and its resulting climate zones. As the host star is a dim red dwarf, the

habitable zone of Gliese 581 is very close to the star itself, and theastronomers show that planet g would be forced by Gliese 581'sgravitational pull into a tidally-locked,synchronous rotationaround thestar with a billion years, so that always keeps the same side orientedtowards the star, just as the Earth's Moon always shows the same facetowards Earth. While the astronomer's model indicates that the star-facingside of the planet is probably a scorching desert, the dark side is probablycovered covered in ice, like Earth's Antarctic. Along the "terminator."between the day and dark sides, however, temperatures should be intransition between planet g's hot and cold extremes, probably in the rangewhereEarth-type lifecould develop. In addition, the planet likely has a

sufficient dense atmosphere, greenhouse gases (i.e., carbon dioxide,methane, and water vapor), and heat transferring winds to render parts ofone or both sides of the planet "potentially habitable" (Lisa Grossman,Wired, November 1, 2010,with video of Gliese 581 g climate model;TudorVieru, Softpedia, November 2, 2010;Heng and Vogt, 2010;andKevinHeng's climate model videos at ETHZ).

Using a simiplified model ofEarth's atmosphere, the scientists set thetemperature at planet g's equator to about 40 Fahrenheit (4.4 Celsius) andassumed that the temperature differential between the equator and thepoles was similar to Earths, about 60 F (15.6 C) and that certainproperties of the atmosphere, like the amount of heat it can absorb and thesurface pressure, were just like Earths. After the scientists ran their modelran for 1,200 Earth-days (but discarding the first 200) to observe thedevelopment of stable, long-term weather patterns, the model generatedthe flow of a constant light wind around the entire planet like a slow jetstream, which pulled warm air into a V-shape. In their paper, the scientistsshow that the most temperate areas on planet g would be located along asideways V-shaped curve or chevron. As shown in the illustration above,the most comfortable region is probably located in the vortices of thechevron, which would be the warmer spots. If Gliese 581 g is eventuallyconfirmed by additional observational data by other astronomers, thescientists believe that planetary modellers now have the computer powerto make some interesting conclusions about where any life that developson its surface would be most comfortable.
http://www.solstation.com/planets/super-earths.htmhttp://www.solstation.com/planets/super-earths.htmhttp://www.solstation.com/planets/super-earths.htmhttp://en.wikipedia.org/wiki/Synchronous_rotationhttp://en.wikipedia.org/wiki/Synchronous_rotationhttp://en.wikipedia.org/wiki/Synchronous_rotationhttp://en.wikipedia.org/wiki/Terminator_%28solar%29http://en.wikipedia.org/wiki/Terminator_%28solar%29http://www.solstation.com/life/ear-life.htmhttp://www.solstation.com/life/ear-life.htmhttp://www.solstation.com/life/ear-life.htmhttp://www.wired.com/wiredscience/2010/11/gliese-581g-climate/http://www.wired.com/wiredscience/2010/11/gliese-581g-climate/http://www.wired.com/wiredscience/2010/11/gliese-581g-climate/http://www.wired.com/wiredscience/2010/11/gliese-581g-climate/http://www.wired.com/wiredscience/2010/11/gliese-581g-climate/http://news.softpedia.com/news/Second-Earth-s-Atmosphere-Modeled-164232.shtmlhttp://news.softpedia.com/news/Second-Earth-s-Atmosphere-Modeled-164232.shtmlhttp://news.softpedia.com/news/Second-Earth-s-Atmosphere-Modeled-164232.shtmlhttp://news.softpedia.com/news/Second-Earth-s-Atmosphere-Modeled-164232.shtmlhttp://arxiv.org/abs/1010.4719http://arxiv.org/abs/1010.4719http://arxiv.org/abs/1010.4719http://www.phys.ethz.ch/~kheng/fms/http://www.phys.ethz.ch/~kheng/fms/http://www.phys.ethz.ch/~kheng/fms/http://www.phys.ethz.ch/~kheng/fms/http://www.solstation.com/stars/earth.htmhttp://www.solstation.com/stars/earth.htmhttp://www.solstation.com/stars/earth.htmhttp://www.solstation.com/stars/earth.htmhttp://www.phys.ethz.ch/~kheng/fms/http://www.phys.ethz.ch/~kheng/fms/http://arxiv.org/abs/1010.4719http://news.softpedia.com/news/Second-Earth-s-Atmosphere-Modeled-164232.shtmlhttp://news.softpedia.com/news/Second-Earth-s-Atmosphere-Modeled-164232.shtmlhttp://www.wired.com/wiredscience/2010/11/gliese-581g-climate/http://www.wired.com/wiredscience/2010/11/gliese-581g-climate/http://www.solstation.com/life/ear-life.htmhttp://en.wikipedia.org/wiki/Terminator_%28solar%29http://en.wikipedia.org/wiki/Synchronous_rotationhttp://www.solstation.com/planets/super-earths.htm


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ESO,unknow n art is t

Largeri l lustrat ion.

Orbi t ing wel l outs ide of Gl iese 581's

narrow and c lose-in, red-dwarf star

habitable zone, planetary candidate " f"

appears to be a fr ig id super-Earth (NASA

2010 new sand ESO2007 new s).

Planet f- The astronomers alsodetected a larger but likely to be frigid super-Earth in an outermost orbit.With at least 7.0 Earth-masses, planetary candidate "f" has an average

orbital distance of about 0.758 +/- 0.015 AUs. It's presumed highly circularorbit takes around 433 days (just under 1.2 years) to complete. (NASAnewsrelease;Carnegienews release;U.C. at Santa Cruzpress release;NSFvideo announcement;Amir Alexander, Planetary News, October 6, 2010;David Shiga, New Scient is t, September 29, 2010;Dennis Overbye, NewYork Times, September 29, 2010;andVogt et al, 2010).)

Radial-velocity measurements of the star indicates that no Jupiter-mass planetorbits Gliese 581 with a period less than about 10 years (Bonfils et al, 2005).

Closest Neighbors

The following star systems are located within 10 ly of Gliese 581.

------------------------------------- [Guide]-- [Full Near Star Map] -------------------------------------

Star SystemSpectra &

Luminosity

Distance

(light-years)

BD-11 3759 M3.5 V 4.3

LP 914-54 M8 V 6.8
http://www.eso.org/http://www.eso.org/http://www.eso.org/http://www.solstation.com/stars/gl581pl2.jpghttp://www.solstation.com/stars/gl581pl2.jpghttp://www.nasa.gov/topics/universe/features/gliese_581_feature.htmlhttp://www.nasa.gov/topics/universe/features/gliese_581_feature.htmlhttp://www.eso.org/outreach/press-rel/pr-2007/pr-22-07.htmlhttp://www.eso.org/outreach/press-rel/pr-2007/pr-22-07.htmlhttp://www.eso.org/outreach/press-rel/pr-2007/pr-22-07.htmlhttp://www.nasa.gov/topics/universe/features/gliese_581_feature.htmlhttp://www.nasa.gov/topics/universe/features/gliese_581_feature.htmlhttp://www.nasa.gov/topics/universe/features/gliese_581_feature.htmlhttp://www.nasa.gov/topics/universe/features/gliese_581_feature.htmlhttp://carnegiescience.edu/news/potentially_habitable_planet_discoveredhttp://carnegiescience.edu/news/potentially_habitable_planet_discoveredhttp://carnegiescience.edu/news/potentially_habitable_planet_discoveredhttp://news.ucsc.edu/2010/09/planet.htmlhttp://news.ucsc.edu/2010/09/planet.htmlhttp://news.ucsc.edu/2010/09/planet.htmlhttp://www.nsf.gov/news/news_videos.jsp?cntn_id=117765&media_id=68454&org=NSFhttp://www.nsf.gov/news/news_videos.jsp?cntn_id=117765&media_id=68454&org=NSFhttp://planetary.org/news/2010/1006_Billions_and_Billions_Discovery_of.htmlhttp://planetary.org/news/2010/1006_Billions_and_Billions_Discovery_of.htmlhttp://planetary.org/news/2010/1006_Billions_and_Billions_Discovery_of.htmlhttp://www.newscientist.com/article/dn19519-found-first-rocky-exoplanet-that-could-host-life.htmlhttp://www.newscientist.com/article/dn19519-found-first-rocky-exoplanet-that-could-host-life.htmlhttp://www.newscientist.com/article/dn19519-found-first-rocky-exoplanet-that-could-host-life.htmlhttp://www.newscientist.com/article/dn19519-found-first-rocky-exoplanet-that-could-host-life.htmlhttp://www.nytimes.com/2010/09/30/science/space/30planet.htmlhttp://www.nytimes.com/2010/09/30/science/space/30planet.htmlhttp://www.nytimes.com/2010/09/30/science/space/30planet.htmlhttp://www.nytimes.com/2010/09/30/science/space/30planet.htmlhttp://www.nytimes.com/2010/09/30/science/space/30planet.htmlhttp://www.nytimes.com/2010/09/30/science/space/30planet.htmlhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.ucolick.org/~vogt/ms_press-1.pdfhttp://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2005A%26A...443L..15B&db_key=AST&data_type=HTML&format=&high=438efdb553254688http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2005A%26A...443L..15B&db_key=AST&data_type=HTML&format=&high=438efdb553254688http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2005A%26A...443L..15B&db_key=AST&data_type=HTML&format=&high=438efdb553254688http://www.solstation.com/m-guide.htmhttp://www.solstation.com/m-guide.htmhttp://www.solstation.com/m-guide.htmhttp://www.solstation.com/47ly-ns.htmhttp://www.solstation.com/47ly-ns.htmhttp://www.solstation.com/47ly-ns.htmhttp://www.solstation.com/stars/gl581pl2.jpghttp://www.solstation.com/47ly-ns.htmhttp://www.solstation.com/m-guide.htmhttp://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2005A%26A...443L..15B&db_key=AST&data_type=HTML&format=&high=438efdb553254688http://www.ucolick.org/~vogt/ms_press-1.pdfhttp://www.nytimes.com/2010/09/30/science/space/30planet.htmlhttp://www.nytimes.com/2010/09/30/science/space/30planet.htmlhttp://www.newscientist.com/article/dn19519-found-first-rocky-exoplanet-that-could-host-life.htmlhttp://planetary.org/news/2010/1006_Billions_and_Billions_Discovery_of.htmlhttp://www.nsf.gov/news/news_videos.jsp?cntn_id=117765&media_id=68454&org=NSFhttp://news.ucsc.edu/2010/09/planet.htmlhttp://carnegiescience.edu/news/potentially_habitable_planet_discoveredhttp://www.nasa.gov/topics/universe/features/gliese_581_feature.htmlhttp://www.nasa.gov/topics/universe/features/gliese_581_feature.htmlhttp://www.eso.org/outreach/press-rel/pr-2007/pr-22-07.htmlhttp://www.nasa.gov/topics/universe/features/gliese_581_feature.htmlhttp://www.solstation.com/stars/gl581pl2.jpghttp://www.eso.org/


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Gl 570/HR 5568 ABCK4-5 VeM1 VM3 V

6.9

L 768-119 M3.5-5 V 8.2

Wolf 630 ABC

M2.5 Ve

M4-5 VeM7 V

8.2

Hip 72509 M V 8.2

BD-12 4523 ABM3.0 V?

8.4

Wolf 629 ABM3.5 V?

8.6

CD-25 10553 ABM3 VM3 V

8.7

Other Informationo Up-to-date technical summaries on Gliese 581 can be found at: Jean

Schneider'sExtrasolar Planets Encyclopaedia;Astronomiches Rechen-Institut at Heidelberg'sARICNS,theNASA Star and Exoplanet Database,and the Research Consortium on Nearby Stars (RECONS). Additionalinformation may be available at Roger Wilcox'sInternet Stellar Database.

o The ancient Greeks grouped the stars of Libra with Constellation Scorpius,the Scorpion. To the later Romans, however, Constellation Libra represent"the Scales of Justice" held by Julius Caesar. For later peoples, thesescales became associated with Virgo as the Goddess of Justice, proving

that political power is indeed fleeting. . For more information about thestars and objects in this constellation, go to Christine Kronberg'sLibra.Foran illustration, see David Haworth'sLibra.

o For more information about stars including spectral and luminosity classcodes, go to ChView's webpage onThe Stars of the Milky Way.

1998-2011 Sol Company. All Rights Reserved.
http://www.solstation.com/stars/gl570abc.htmhttp://www.solstation.com/stars/gl570abc.htmhttp://exoplanet.eu/star.php?st=Gl+581http://exoplanet.eu/star.php?st=Gl+581http://exoplanet.eu/star.php?st=Gl+581http://www.ari.uni-heidelberg.de/datenbanken/aricns/cnspages/4c01207.htmhttp://www.ari.uni-heidelberg.de/datenbanken/aricns/cnspages/4c01207.htmhttp://www.ari.uni-heidelberg.de/datenbanken/aricns/cnspages/4c01207.htmhttp://nsted.ipac.caltech.edu/cgi-bin/Sieve/nph-sieve?mission=NStED&currentForm=Result&objectSearch&stripped=&obj=HIP%2074995&id=74995&aliases=/work/TMP_uCG8tH/NStED/default/aliases_74995http://nsted.ipac.caltech.edu/cgi-bin/Sieve/nph-sieve?mission=NStED&currentForm=Result&objectSearch&stripped=&obj=HIP%2074995&id=74995&aliases=/work/TMP_uCG8tH/NStED/default/aliases_74995http://nsted.ipac.caltech.edu/cgi-bin/Sieve/nph-sieve?mission=NStED&currentForm=Result&objectSearch&stripped=&obj=HIP%2074995&id=74995&aliases=/work/TMP_uCG8tH/NStED/default/aliases_74995http://joy.chara.gsu.edu/RECONS/http://joy.chara.gsu.edu/RECONS/http://joy.chara.gsu.edu/RECONS/http://www.stellar-database.com/http://www.stellar-database.com/http://www.stellar-database.com/http://www.seds.org/Maps/Stars_en/Fig/libra.htmlhttp://www.seds.org/Maps/Stars_en/Fig/libra.htmlhttp://www.seds.org/Maps/Stars_en/Fig/libra.htmlhttp://www.stargazing.net/David/constel/constel/libra.htmlhttp://www.stargazing.net/David/constel/constel/libra.htmlhttp://www.stargazing.net/David/constel/constel/libra.htmlhttp://members.nova.org/~sol/chview/chv5.htmhttp://members.nova.org/~sol/chview/chv5.htmhttp://members.nova.org/~sol/chview/chv5.htmhttp://members.nova.org/~sol/chview/chv5.htmhttp://www.stargazing.net/David/constel/constel/libra.htmlhttp://www.seds.org/Maps/Stars_en/Fig/libra.htmlhttp://www.stellar-database.com/http://joy.chara.gsu.edu/RECONS/http://nsted.ipac.caltech.edu/cgi-bin/Sieve/nph-sieve?mission=NStED&currentForm=Result&objectSearch&stripped=&obj=HIP%2074995&id=74995&aliases=/work/TMP_uCG8tH/NStED/default/aliases_74995http://www.ari.uni-heidelberg.de/datenbanken/aricns/cnspages/4c01207.htmhttp://exoplanet.eu/star.php?st=Gl+581http://www.solstation.com/stars/gl570abc.htm


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Article:http://www.space.com/9229-alien-world-tour-exoplanets-star-gliese-581.html

Alien World Tour: The Exoplanets Around

Star Gliese 581by Mike Wall, SPACE.com Senior WriterDate: 29 September 2010 Time: 06:55 PM ETSHARE

This artist's conception shows the inner four planetsof the Gliese 581 system and their host star, a reddwarf only 20 light-years from Earth. The largeplanet in the foreground is Gliese 581g, whosediscovery was announced in September 2010. Theplanet is in the middle of the star's habitable zoneand is only three to four times as massive as Earth.CREDIT: Lynette Cook

The announcement Wednesday (Sept. 29) of two newfound alien planets circling the star Gliese 581adds to the nearby solar system's intrigue, further cementing its status as a top candidate to harborextraterrestrial life.

One of the two newly discovered planets, known asGliese 581g,is asmall,Earth-like world that likely lieswithin its star's habitable zone ? the just-right range of distances that allow liquid water to exist. [Artist'sconception of Gliese 581g.]

Astronomers have now detected six planets orbiting Gliese 581, the most known to circle any star beyondour own sun. Here's a brief tour of the star and its planets, from the inside out:
http://www.space.com/science-astronomy/archive.htmlhttp://www.space.com/science-astronomy/archive.htmlhttp://www.space.com/9225-odds-life-newfound-earth-size-planet-100-percent-astronomer.htmlhttp://www.space.com/9225-odds-life-newfound-earth-size-planet-100-percent-astronomer.htmlhttp://www.space.com/9225-odds-life-newfound-earth-size-planet-100-percent-astronomer.htmlhttp://www.space.com/9229-alien-world-tour-exoplanets-star-gliese-581.htmlhttp://www.space.com/9229-alien-world-tour-exoplanets-star-gliese-581.htmlhttp://www.space.com/9229-alien-world-tour-exoplanets-star-gliese-581.htmlhttp://www.space.com/php/multimedia/imagedisplay/img_display.php?pic=earth-like-planet-100929-02.jpg&cap=This+artist%27s+conception+shows+the+inner+four+planets+of+the+Gliese+581+system+and+their+host+star,+a+red+dwarf+star+only+20+light+years+away+from+Earth.+The+large+planet+in+the+foreground+is+the+newly+discovered+GJ+581g,+which+has+a+37-day+orbit+right+in+the+middle+of+the+star%27s+habitable+zone+and+is+only+three+to+four+times+the+mass+of+Earth,+with+a+diameter+1.2+to+1.4+times+that+of+Earth.+Credit:+Lynette+Cook+%5b%3Ca+href=/9225-odds-life-newfound-earth-size-planet-100-percent-astronomer.html%3EFull+Story%3C/a%3E%5dhttp://www.space.com/php/multimedia/imagedisplay/img_display.php?pic=earth-like-planet-100929-02.jpg&cap=This+artist%27s+conception+shows+the+inner+four+planets+of+the+Gliese+581+system+and+their+host+star,+a+red+dwarf+star+only+20+light+years+away+from+Earth.+The+large+planet+in+the+foreground+is+the+newly+discovered+GJ+581g,+which+has+a+37-day+orbit+right+in+the+middle+of+the+star%27s+habitable+zone+and+is+only+three+to+four+times+the+mass+of+Earth,+with+a+diameter+1.2+to+1.4+times+that+of+Earth.+Credit:+Lynette+Cook+%5b%3Ca+href=/9225-odds-life-newfound-earth-size-planet-100-percent-astronomer.html%3EFull+Story%3C/a%3E%5dhttp://www.space.com/php/multimedia/imagedisplay/img_display.php?pic=earth-like-planet-100929-02.jpg&cap=This+artist%27s+conception+shows+the+inner+four+planets+of+the+Gliese+581+system+and+their+host+star,+a+red+dwarf+star+only+20+light+years+away+from+Earth.+The+large+planet+in+the+foreground+is+the+newly+discovered+GJ+581g,+which+has+a+37-day+orbit+right+in+the+middle+of+the+star%27s+habitable+zone+and+is+only+three+to+four+times+the+mass+of+Earth,+with+a+diameter+1.2+to+1.4+times+that+of+Earth.+Credit:+Lynette+Cook+%5b%3Ca+href=/9225-odds-life-newfound-earth-size-planet-100-percent-astronomer.html%3EFull+Story%3C/a%3E%5dhttp://www.space.com/php/multimedia/imagedisplay/img_display.php?pic=earth-like-planet-100929-02.jpg&cap=This+artist%27s+conception+shows+the+inner+four+planets+of+the+Gliese+581+system+and+their+host+star,+a+red+dwarf+star+only+20+light+years+away+from+Earth.+The+large+planet+in+the+foreground+is+the+newly+discovered+GJ+581g,+which+has+a+37-day+orbit+right+in+the+middle+of+the+star%27s+habitable+zone+and+is+only+three+to+four+times+the+mass+of+Earth,+with+a+diameter+1.2+to+1.4+times+that+of+Earth.+Credit:+Lynette+Cook+%5b%3Ca+href=/9225-odds-life-newfound-earth-size-planet-100-percent-astronomer.html%3EFull+Story%3C/a%3E%5dhttp://www.facebook.com/sharer.php?u=http://www.space.com/9229-alien-world-tour-exoplanets-star-gliese-581.html&t=Alien+World+Tour:+The+Exoplanets+Around+Star+Gliese+581http://www.facebook.com/sharer.php?u=http://www.space.com/9229-alien-world-tour-exoplanets-star-gliese-581.html&t=Alien+World+Tour:+The+Exoplanets+Around+Star+Gliese+581http://www.facebook.com/sharer.php?u=http://www.space.com/9229-alien-world-tour-exoplanets-star-gliese-581.html&t=Alien+World+Tour:+The+Exoplanets+Around+Star+Gliese+581http://www.space.com/php/multimedia/imagedisplay/img_display.php?pic=earth-like-planet-100929-02.jpg&cap=This+artist%27s+conception+shows+the+inner+four+planets+of+the+Gliese+581+system+and+their+host+star,+a+red+dwarf+star+only+20+light+years+away+from+Earth.+The+large+planet+in+the+foreground+is+the+newly+discovered+GJ+581g,+which+has+a+37-day+orbit+right+in+the+middle+of+the+star%27s+habitable+zone+and+is+only+three+to+four+times+the+mass+of+Earth,+with+a+diameter+1.2+to+1.4+times+that+of+Earth.+Credit:+Lynette+Cook+%5b%3Ca+href=/9225-odds-life-newfound-earth-size-planet-100-percent-astronomer.html%3EFull+Story%3C/a%3E%5dhttp://www.space.com/php/multimedia/imagedisplay/img_display.php?pic=earth-like-planet-100929-02.jpg&cap=This+artist%27s+conception+shows+the+inner+four+planets+of+the+Gliese+581+system+and+their+host+star,+a+red+dwarf+star+only+20+light+years+away+from+Earth.+The+large+planet+in+the+foreground+is+the+newly+discovered+GJ+581g,+which+has+a+37-day+orbit+right+in+the+middle+of+the+star%27s+habitable+zone+and+is+only+three+to+four+times+the+mass+of+Earth,+with+a+diameter+1.2+to+1.4+times+that+of+Earth.+Credit:+Lynette+Cook+%5b%3Ca+href=/9225-odds-life-newfound-earth-size-planet-100-percent-astronomer.html%3EFull+Story%3C/a%3E%5dhttp://www.space.com/9229-alien-world-tour-exoplanets-star-gliese-581.htmlhttp://www.space.com/9225-odds-life-newfound-earth-size-planet-100-percent-astronomer.htmlhttp://www.space.com/science-astronomy/archive.html


18/28

Gliese 581: the mother star

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Gliese 581 is a red dwarf located 20.5 light-years from Earth, in the constellation Libra. Like other reddwarfs, it'ssmallerand much dimmer than our sun. Scientists believe Gliese 581 is old ? at least a fewbillion years ? and relatively stable. Both are qualities conducive to the evolution of life, scientists havesaid.

Nearest planet

The nearest planet to the star is Gliese 581e, a rocky worldnearly twice as massive as Earth.

Gliese 581e is extremely close to its parent star ? it completes an orbit every 3.15 days ? so it's likely fartoo hot for life to have any chance of taking root.

Gliese 581e is about 0.033 astronomical units from its parent star. One astronomical unit, or AU, is theaverage distance between the Earth and sun, about 93 million miles (150 million km).

Astronomers announced this planet's discovery in April 2009, and it's in the running for thelightestknownextrasolar planet. So far, the only potential alien planet less massive than Gliese 581e is a world about1.4 times the mass of Earth, but its existence ? around a more distant star ? has not yet been confirmed.

Next up: Gliese581b

Traveling outward, the next planet is Gliese 581b, a Neptune-size alien worldthat's about 16 times asmassive as Earth. This planet is still very close to the star, completing an orbit in 5.4 days.

Astronomers first discovered this planet in December 2005, according to an extrasolar planet databasemaintained by NASA's Jet Propulsion Laboratory. Its average distance from the Gliese 581 star is about0.041 AU.

Rocky world in third

Gliese 581c comes next. This is a rocky, smallish planet ? about five Earth masses ? that makes a full triparound the red dwarf every 15 days.

Astronomer

Documents

Research Outline - Gliese 581 Paper