M77 (NGC 1068)

M77 (NGC 1068)M77 (NGC 1068)

By: Ryan Desautels

Messier 77Messier 77

A Brief HistoryA Brief History General InformationGeneral Information Galactic InformationGalactic Information

AGNAGN SeyfertSeyfert

Research QuestionResearch Question Does M77 have a Does M77 have a

barred structure?barred structure? Does the brightness Does the brightness

change, is it possible to change, is it possible to detect this change?detect this change?

SummarySummary

A Brief HistoryA Brief History

October 29October 29thth, 1780;, 1780; First observation made of NGC 1068 by M. Mechain.First observation made of NGC 1068 by M. Mechain. He described it as a nebulaHe described it as a nebula

http://www.seds.org/messier/m/m077.htmlhttp://www.seds.org/messier/m/m077.html

December 17December 17thth, 1780;, 1780; Observed by Charles Messier and catalogued as Observed by Charles Messier and catalogued as

“Cluster of faint stars, which contains nebulosity…” (Charles “Cluster of faint stars, which contains nebulosity…” (Charles Messier, Messier, CatalogueCatalogue).).

http://www.kopernik.org/images/archive/m77.htmhttp://www.kopernik.org/images/archive/m77.htm

Other notable early observations;Other notable early observations; W. Hershel described M77 as a cluster of stars.W. Hershel described M77 as a cluster of stars.


Rosse was the first astronomer to recognize M77 as a galaxy Rosse was the first astronomer to recognize M77 as a galaxy and not a star cluster.and not a star cluster.


General InformationGeneral Information

TypeTypeWhat type of galaxy is Messier 77?What type of galaxy is Messier 77?

SizeSizeWhat are some of the dimensions of Messier 77?What are some of the dimensions of Messier 77?

BrightnessBrightnessWhat is the brightness of Messier 77 and some of What is the brightness of Messier 77 and some of

its oddities?its oddities?

TypeType

NGC 1068 is a spiral galaxy (barred?).NGC 1068 is a spiral galaxy (barred?). Type Sb using Hubble’s Tuning Fork Diagram.Type Sb using Hubble’s Tuning Fork Diagram.

I will give an argument why this classification is no I will give an argument why this classification is no longer accurate.longer accurate.

Part of a group of galaxies known as Part of a group of galaxies known as Seyfert Galaxies.Seyfert Galaxies.

Seyfert Galaxies are a subset of galaxies and other Seyfert Galaxies are a subset of galaxies and other objects known as Active Galactic Nuclei (AGN).objects known as Active Galactic Nuclei (AGN).

M77 is the prototype galaxy for the Seyfert class.M77 is the prototype galaxy for the Seyfert class.

Bar or no bar?Bar or no bar?

Well, according to Well, according to Gilbert A. Gilbert A. Esquerdo and Esquerdo and John C. Barentine, John C. Barentine, there is a barred there is a barred structure present, structure present, at least in IR at least in IR wavelengths.wavelengths.

N

W

Bar in optical?Bar in optical?

SizeSize

M77 is slightly larger then our own Milky M77 is slightly larger then our own Milky Way.Way.

M77 has an extent of roughly 170 000 light M77 has an extent of roughly 170 000 light years with a core (brightest area) that years with a core (brightest area) that makes up about 71% of it’s total size makes up about 71% of it’s total size (120 000 light years).(120 000 light years).

It is at a distance of approximately 60 It is at a distance of approximately 60 million light years.million light years.

SizeSize

120 000ly

BrightnessBrightness

Messier 77 has a brightness that varies Messier 77 has a brightness that varies (most observatories and papers classify (most observatories and papers classify the brightness somewhere in the range of the brightness somewhere in the range of 8.9 to 10.5).8.9 to 10.5).

Brightness variations is a property of Brightness variations is a property of Seyfert galaxies. Not only do they vary in Seyfert galaxies. Not only do they vary in brightness, they can also vary in class.brightness, they can also vary in class.

Messier 77 has a period of less then a Messier 77 has a period of less then a week.week.

BrightnessBrightness

The core of M77 is very similar to that of a The core of M77 is very similar to that of a star (point source). Which is a property of star (point source). Which is a property of Seyfert Galaxies.Seyfert Galaxies.

Active Galactic Nuclei (AGN)Active Galactic Nuclei (AGN)

A little background information on AGN’sA little background information on AGN’sWhat are AGN’sWhat are AGN’sAre there different types of AGN’s, if so, what Are there different types of AGN’s, if so, what

are theyare theyBasic properties of AGN’sBasic properties of AGN’s

What are AGN’sWhat are AGN’s

As a group, they are the most active As a group, they are the most active galaxies out there.galaxies out there.

Galaxies who’s nuclei alone produce more Galaxies who’s nuclei alone produce more radiation then the rest of the galaxy.radiation then the rest of the galaxy.

The widely accepted model of an AGN The widely accepted model of an AGN galaxy is that it has a central super galaxy is that it has a central super massive black hole as it’s engine.massive black hole as it’s engine.

Different types of AGN’sDifferent types of AGN’s

AGN’s are a general class of galaxiesAGN’s are a general class of galaxiesSeyfert GalaxiesSeyfert Galaxies

Type 1, and 2Type 1, and 2

Radio GalaxiesRadio GalaxiesRadio luminosity > 10Radio luminosity > 103333 W W

Quasars Quasars Very distant AGN’sVery distant AGN’s

BL Lacertae ObjectsBL Lacertae Objects

Basic properties of AGN’sBasic properties of AGN’s

AGN’s as a group show all or most of the AGN’s as a group show all or most of the following characteristics.following characteristics.High luminosity greater then 10High luminosity greater then 1037 37 W.W.Nonthermal emission, with excessive UV, IR, Nonthermal emission, with excessive UV, IR,

Radio and X-Ray flux (compared to most Radio and X-Ray flux (compared to most galaxies).galaxies).

Small region of rapid variability.Small region of rapid variability.High contrast of brightness between nucleus High contrast of brightness between nucleus

and other structures (large scale).and other structures (large scale).Broad emission lines (sometimes).Broad emission lines (sometimes).

Seyfert GalaxiesSeyfert Galaxies

First discovered by Carl K. Seyfert.First discovered by Carl K. Seyfert. Messier 77 is the prototype Seyfert Galaxy.Messier 77 is the prototype Seyfert Galaxy.

What are Seyfert Galaxies?What are Seyfert Galaxies?What are the different types?What are the different types?

Type: 1,1.5,2Type: 1,1.5,2What do different Seyfert galaxies share in What do different Seyfert galaxies share in

common.common.How is M77 a Seyfert Galaxy.How is M77 a Seyfert Galaxy.

Carl K. SeyfertCarl K. Seyfert Pioneered research on nuclear emission in spiral Pioneered research on nuclear emission in spiral

galaxies.galaxies. 1943 he published a paper on galaxies with 1943 he published a paper on galaxies with

bright nuclei that exhibit characteristically bright nuclei that exhibit characteristically broadened emission lines.broadened emission lines.

While at Warner Swasey Observatory and the While at Warner Swasey Observatory and the Case Institute, he obtained the first good colour Case Institute, he obtained the first good colour photographs of nebulae and stellar spectra.photographs of nebulae and stellar spectra.

Involved in instrumental innovations which Involved in instrumental innovations which included the use of photomultiplier tubes and included the use of photomultiplier tubes and television techniques in astronomy, and television techniques in astronomy, and electronically controlled telescope drives.electronically controlled telescope drives.

Different Types of Seyfert GalaxiesDifferent Types of Seyfert Galaxies

There are two different types of Seyfert There are two different types of Seyfert Galaxies.Galaxies.

NGC 5548 M77

Type 1 Type 2

Type 1Type 1

Type 1 galaxies have two sets of emission Type 1 galaxies have two sets of emission lines in their spectra:lines in their spectra:

Narrow lines, with widths of several hundred km/sNarrow lines, with widths of several hundred km/s Broad lines, with widths of up to 10Broad lines, with widths of up to 1044 km/s km/s

Type 2Type 2

Object has only narrow lines present. Object has only narrow lines present.

Why different typesWhy different types

Types 1 and 2 are only different because Types 1 and 2 are only different because of our point of view. It is thought that the of our point of view. It is thought that the differences are due to a torus which is differences are due to a torus which is preventing us from seeing the broad preventing us from seeing the broad regions in Seyfert 2 galaxies.regions in Seyfert 2 galaxies.

Messier 77’s variabilityMessier 77’s variability

Is it possible to detect the variability?Is it possible to detect the variability? If it is possible, what is the range in If it is possible, what is the range in

apparent magnitude?apparent magnitude?

VariabilityVariability

To find the variability:To find the variability:Measure each individual object image.Measure each individual object image.

Set the mean value of each object image ~ 0Set the mean value of each object image ~ 0

Measure the FWHM of a non-variable star in the Measure the FWHM of a non-variable star in the field.field.

Measure an area around the star .Measure an area around the star . ~ 4x FWHM.~ 4x FWHM.

Adjust each image so that the star brightness Adjust each image so that the star brightness (mean value) is the same in each object image.(mean value) is the same in each object image.


Measure the FWHM of the galaxy.Measure the FWHM of the galaxy.Measure an area around the core of the galaxy.Measure an area around the core of the galaxy.

~ 4x FWHM~ 4x FWHM

Using the formula:Using the formula: m-n = (2.5)log(Fn/Fm),m-n = (2.5)log(Fn/Fm),

Where m-n = the change in brightness,Where m-n = the change in brightness, Fn = the mean value of the star,Fn = the mean value of the star, Fm = the mean value of the galaxy.Fm = the mean value of the galaxy.







We can see from the previous graph that We can see from the previous graph that there is some variability.there is some variability.

There is a change in variability of 0.07.There is a change in variability of 0.07.This change is quite small, however; it is This change is quite small, however; it is

greater then the error so I can say that greater then the error so I can say that there is definitely a change in brightness.there is definitely a change in brightness.

SummarySummary

Messier 77 is a Sb Type 2 Seyfert Galaxy.Messier 77 is a Sb Type 2 Seyfert Galaxy. It satisfies some of the criterion of the It satisfies some of the criterion of the

AGN model.AGN model.

SummarySummary

Small region of rapid variability.Small region of rapid variability.Yes, as shown in my graph the brightness does Yes, as shown in my graph the brightness does

change, and the period of M77 is roughly 1 week.change, and the period of M77 is roughly 1 week. http://www.kopernik.org/images/archive/m77.htmhttp://www.kopernik.org/images/archive/m77.htm

SummarySummary

High contrast of brightness between High contrast of brightness between nucleus and other structures (large scale).nucleus and other structures (large scale).

Yes, it is only with special filters (Digital Development Yes, it is only with special filters (Digital Development Processing DDP), that we are able to make out the Processing DDP), that we are able to make out the central bulge area and the rest of the galaxy.central bulge area and the rest of the galaxy.

SummarySummary

Messier 77 is a galaxy who’s core has an Messier 77 is a galaxy who’s core has an almost stellar output.almost stellar output.

ReferencesReferences Images:Images:

http://www.aao.gov.au/images/captions/aatccd012.htmlhttp://www.aao.gov.au/images/captions/aatccd012.html http://archive.stsci.edu/cgi-bin/dss_form?target=m77&resolver=SIMBADhttp://archive.stsci.edu/cgi-bin/dss_form?target=m77&resolver=SIMBAD http://cas.sdss.org/dr3/en/proj/advanced/galaxies/tuningfork.asphttp://cas.sdss.org/dr3/en/proj/advanced/galaxies/tuningfork.asp http://www.noao.edu/outreach/aop/observers/m77.htmlhttp://www.noao.edu/outreach/aop/observers/m77.html http://nedwww.ipac.caltech.edu/cgi-bin/nph-imgdata?http://nedwww.ipac.caltech.edu/cgi-bin/nph-imgdata?

objid=58240&objname=MESSIER%20077objid=58240&objname=MESSIER%20077 http://www.astrosurf.com/astroduvel/images/m77.htmlhttp://www.astrosurf.com/astroduvel/images/m77.html

Information:Information: http://imagine.gsfc.nasa.gov/docs/science/know_l1/active_galaxies.htmlhttp://imagine.gsfc.nasa.gov/docs/science/know_l1/active_galaxies.html http://www.astr.ua.edu/keel/agn/http://www.astr.ua.edu/keel/agn/ http://www.noao.edu/outreach/aop/observers/m77.htmlhttp://www.noao.edu/outreach/aop/observers/m77.html http://coolcosmos.ipac.caltech.edu/cosmic_classroom/http://coolcosmos.ipac.caltech.edu/cosmic_classroom/

multiwavelength_astronomy/multiwavelength_museum/m77.htmlmultiwavelength_astronomy/multiwavelength_museum/m77.html http://seds.lpl.arizona.edu/messier/more/m077_hst.htmlhttp://seds.lpl.arizona.edu/messier/more/m077_hst.html http://www.messiermarathon.com/new_page_83.htmhttp://www.messiermarathon.com/new_page_83.htm Introductory Astronomy & Astrophysics 4Introductory Astronomy & Astrophysics 4 thth E., 1998 E., 1998 http://www.ne.jp/asahi/stellar/scenes/object_e/m77.htmhttp://www.ne.jp/asahi/stellar/scenes/object_e/m77.htm

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M77 (NGC 1068)