Hubble Observations of Main Belt Comets or Active...

Max Mutchler Space Telescope Science Institute

Baltimore, Maryland

Hubble Science Briefing 6 February 2014

Hubble Observations

of Main Belt Comets

or “Active Asteroids”

The Extraordinary Multi-tailed Main-belt Comet P/2013 P5

Jewitt, David; Agarwal, Jessica; Weaver, Harold;

Mutchler, Max; Larson, Stephen

The Astrophysical Journal Letters, Vol. 778, Issue 1 (2013)

Overview

• This is not our parents asteroid belt! And not the one of

movies and video games either…

• The asteroid belt is more dynamic than imagined a

generation ago

– Main Belt Comets

– A bigger role in the mystery of Earth’s oceans?

• Related discoveries: Ceres, Europa water vapor

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Asteroids: typically rocky, with

circular orbits

between Mars

and Jupiter…

Main Asteroid Belt

3

Comets: typically a mixture of

ices and rock, with

elliptical orbits extending

to the outer Solar

System

Main Asteroid Belt

Comet orbit

4

Video about Main Belt Comets with Star Wars clip!

http://www.youtube.com/watch?v=qchvgRUDUzA 5

6

Citation from IAU Minor Planet Circular 56612 on the naming of

Asteroid “6815 Mutchler”

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Asteroid history and mystery

• Ceres, Vesta, Pallas,

discovered in early 1800s

• Called planets for 50

years, then re-classified:

any déjà vu ?

• Key to understanding

Solar System formation

…and us

• Giveth: our oceans?

• Taketh away: Killed the

dinosaurs? Still a threat?

• Exploration with Hubble,

Dawn…and astronauts? 8

9 Credit: NASA, ESA, and M. Livio and the

Hubble 20th Anniversary Team (STScI)

Star (and planetary system) formation

in the Carina Nebula – see the jets?

10 Credit: NASA, ESA, and M. Livio and the

Hubble 20th Anniversary Team (STScI)

Star (and planetary system) formation

in the Carina Nebula – see the jets?

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Artists impression of a protostar forming: asteroids are leftover

planetesimals from this era – the beginning of the Solar System

Credit: NASA/JPL-Caltech/R. Hurt (SSC)

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Most of the debris left over from planet-building was

ejected from the Solar System

Credit: NASA

Simulation showing the outer planets and planetesimal belt:

a) early configuration, before Jupiter and Saturn reach a 2:1 resonance

b) scattering of planetesimals into the inner Solar System after the

orbital shift of Neptune and Uranus

c) after ejection of planetesimals by planets.

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a) c) b)

The “Nice Model” for the dynamical

history of the Solar System R. Gomes, Hal Levison, Alessandro Morbidelli and Kleomenis Tsiganis, 2005, Nature, 435

Late Heavy Bombardment

14 Image Credit: Julian Baum

15 Image credit: Don Davis / NASA

After the Earth cooled off, later asteroid and comet impacts

may have delivered water and organic material to Earth

– the stuff of life.

Image credit: Don Davis / NASA

But does the water add up?

http://ga.water.usgs.gov/edu/earthhowmuch.html 16

Credit: Howard Perlman, USGS;

globe illustration by Jack Cook,

Woods Hole Oceanographic

Institution (©); Adam Nieman.

Water Ice Discovered on Asteroid for First Time By Clara Moskowitz

SPACE.com Senior Writer

28 April 2010

Water ice has been found on the surface of a nearby asteroid for the first

time – a discovery that could help explain how Earth got its oceans.

Two teams of researchers independently verified that the asteroid 24

Themis – a large rock hurtling through space in the asteroid belt between

Mars and Jupiter – is coated in a layer of frost. They also found that the

asteroid contains organic material, including some molecules that might

be ingredients for life.

The discovery might even provide clues about the origin of water on

Earth. “Our data are certainly at least consistent with the idea that you

could bring in plenty of water from impacts”, said Andrew Rivkin of Johns

Hopkins University. 17

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A comet in the asteroid belt?

Nope!

“A recent disruption of the main-belt asteroid P/2010 A2” David Jewitt, Harold Weaver, Jessica Agarwal, Max Mutchler & Michal Drahus

Nature, Volume 467, 14 October 2010

http://hubblesite.org/newscenter/archive/releases/2010/34/

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Images Credit: NASA, ESA, and D. Jewitt (UCLA)

Illustration by

Ann Feild, STScI

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Research by William F. Bottke, David Vokrouhlicky and David

Nesvorny suggests that the impactor believed to have wiped out

the dinosaurs and other life forms on Earth 65 million years ago

can been traced back to a breakup event in the main asteroid belt.

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Asteroid Scheila:

a “Main Belt Comet” ?

In the wee hours of December 11, 2010,

University of Arizona astronomer Steve Larson

was on cosmic patrol with the Catalina Sky

Survey's Schmidt telescope. That's when he

noticed something odd about the appearance of

the main-belt asteroid 596 Scheila. The

asteroid was clearly fuzzy, with a soft glow

extending a few arcminutes to the west and

north. Other astronomers quickly confirmed the

cometary appearance. If Scheila is truly a long-

dormant comet, then it's a big one: current

estimates put its diameter at 70 miles (113 km).

"It's a main-belt comet, although I don't know

what type yet," Dave Jewitt explains. He says it

could have resulted from an impact (as

occurred earlier this year with P/2010 A2) or

outgassing (as occurs on 133P/Elst-Pizarro).

22 Credit: S. Larson and A. Gibbs (University of Arizona/Catalina Sky Survey)

http://www.skyandtelescope.com/news/112140939.html

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http://hubblesite.org/newscenter/archive/releases/2011/13/ 24

Artists’s impression of a smaller asteroid colliding with much bigger asteroid Scheila:

not all collisions were billions of years ago!

“different causes

for different

objects: impacts,

rotational breakup,

and sublimation”

Asteroids, Comets, Meteors

2012, Niigata, Japan.

LPI No. 1667, id.6152 25

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http://hubblesite.org/newscenter/archive/releases/2013/52/ 27

The YORP effect: solar radiation spinning

up irregularly-shaped small asteroids, and

causing mass loss for the “rubble piles”? 28

29

Artist’s impression: Herschel detects water vapor

emanating from Ceres!

http://www.esa.int/Our_Activities/Space_Science/Herschel/Herschel_discovers_water_vapour_around_dwarf_planet_Ceres

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Artist’s impression: Herschel detects water vapor

emanating from Ceres!

http://www.esa.int/Our_Activities/Space_Science/Herschel/Herschel_discovers_water_vapour_around_dwarf_planet_Ceres

Google hangout about Hubble observations of Vesta and Ceres for the Dawn mission:

http://dawn.jpl.nasa.gov/dawncommunity/Google_hangout_12_05_2013.asp

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dwarf planet asteroid (small solar system body)

Google hangout about Hubble observations of Vesta and Ceres for the Dawn mission:

http://dawn.jpl.nasa.gov/dawncommunity/Google_hangout_12_05_2013.asp

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Why does roundness matter ?

Mars 33

Image credits: Gaspra, Ida: Galileo (NASA/JPL);

Vesta and Mars images: HST (NASA/STScI);

Eros: NEAR Shoemaker (JHU/APL)

Why does roundness matter ?

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Computer model: Credit: NASA/ESA

NASA, ESA, and A. Feild (STScI)

Vesta’s impact crater

Dawn

Vesta

2011

Ceres

2015

35 Image: William K. Hartmann Courtesy of UCLA

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This graphic shows the location of water vapor detected over Europa's south pole that

provides the first strong evidence of water plumes erupting off Europa's surface.

Hubble didn't photograph plumes, but spectroscopically detected auroral emissions

from oxygen and hydrogen. The aurora is powered by Jupiter's magnetic field. The

image of Europa is derived from a global surface map generated from Voyager and

Galileo observations.

Science Credit: NASA, ESA, L. Roth (Southwest Research Institute and University of Cologne, Germany), J. Saur (University of

Cologne, Germany), K. Retherford (Southwest Research Institute), D. Strobel and P. Feldman (Johns Hopkins University),

M. McGrath (Marshall Space Flight Center), and F. Nimmo (University of California, Santa Cruz)

NASA/ESA/L. Roth (Southwest Research

Institute and University of Cologne, Germany)

This is an artist's concept of a

plume of water vapor thought to

be ejected off of the frigid, icy

surface of the Jovian moon

Europa, located 500 million miles

from the Sun.

Hubble Space Telescope

spectroscopic measurements

lead scientists to calculate that

the plume rises to an altitude of

125 miles and then probably

rains frost back onto the moon's

surface. Previous findings

already point to a subsurface

ocean under Europa's icy crust.

Artwork Credit: NASA, ESA, and K. Retherford

(Southwest Research Institute)

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This is an artist's concept of a

plume of water vapor thought to

be ejected off of the frigid, icy

surface of the Jovian moon

Europa, located 500 million miles

from the Sun.

Hubble Space Telescope

spectroscopic measurements

lead scientists to calculate that

the plume rises to an altitude of

125 miles and then probably

rains frost back onto the moon's

surface. Previous findings

already point to a subsurface

ocean under Europa's icy crust.

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Artwork Credit: NASA, ESA, and K. Retherford

(Southwest Research Institute)

… fish added by Max!

Hubble observations of Main Belt Comets or "active asteroids"

Since 2010, a series of Hubble observations has been conducted to help characterize a

recently discovered class of Solar System objects known as Main Belt Comets. These objects

can be more accurately described as “active asteroids” -- they have circular orbits in the Main

Asteroid Belt, but they appear to exhibit comet-like activity. A recent observation revealed an

asteroid sprouting six tails! Along with discoveries of frosty asteroids, and water vapor

emanating from the largest asteroid Ceres, there is the tantalizing possibility that Main Belt

Asteroids can help explain how Earth's oceans formed.

Max Mutchler has been working on the entire Hubble mission -- almost 24 years -- and is

currently the head of the Research and Instrument Analysis Branch at the Space Telescope

Science Institute. Max is an expert on Hubble’s cameras, and has been involved in a wide

range of scientific observations with them. As a member of the Hubble Heritage team, he has

helped produce many of the iconic images that Hubble is famous for. In particular, Max loves

the challenge of observing Solar System objects with Hubble. He is a member of the team that

has discovered four moons of Pluto in support of the New Horizons mission, and he has also

worked with the Dawn mission to observe Vesta and Ceres with Hubble.

Hubble press release and Google Hangout with Dave Jewitt covering 6-tailed asteroid “P5”:

http://hubblesite.org/newscenter/archive/releases/2013/52/

http://www.youtube.com/watch?v=CGgRNWUFfZ0

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