APOD: Two Rings for Asteroid Chariklo (2014 Apr 09)

Comments and questions about the APOD on the main view screen.
User avatar
APOD Robot
Otto Posterman
Posts: 4730
Joined: Fri Dec 04, 2009 3:27 am

APOD: Two Rings for Asteroid Chariklo (2014 Apr 09)

Post by APOD Robot » Wed Apr 09, 2014 4:08 am

Image Two Rings for Asteroid Chariklo

Explanation: Asteroids can have rings. In a surprising discovery announced two weeks ago, the distant asteroid 10199 Chariklo was found to have at least two orbiting rings. Chariklo's diameter of about 250 kilometers makes it the largest of the measured centaur asteroids, but now the smallest known object to have rings. The centaur-class minor planet orbits the Sun between Saturn and Uranus. The above video gives an artist's illustration of how the rings were discovered. As Chariklo passed in 2013 in front of a faint star, unexpected but symmetric dips in the brightness of the star revealed the rings. Planetary astronomers are now running computer simulations designed to investigate how Chariklo's unexpected ring system might have formed, how it survives, and given the asteroid's low mass and close passes of other small asteroids and the planet Uranus, how long it may last.

<< Previous APOD This Day in APOD Next APOD >>
[/b]

User avatar
Ann
4725 Å
Posts: 12170
Joined: Sat May 29, 2010 5:33 am

Re: APOD: Two Rings for Asteroid Chariklo (2014 Apr 09)

Post by Ann » Wed Apr 09, 2014 4:11 am

Click to play embedded YouTube video.
Ring, ring!

Ann
Color Commentator

User avatar
Nitpicker
Inverse Square
Posts: 2692
Joined: Fri Sep 20, 2013 2:39 am
Location: S27 E153

Re: APOD: Two Rings for Asteroid Chariklo (2014 Apr 09)

Post by Nitpicker » Wed Apr 09, 2014 5:37 am

Very interesting. I wonder if we'll have to wait for Chariklo (mag ~18) to occult another star like UCAC4 248-108672 (mag ~12, I think), before we'll know if the rings are still there?

(Or maybe a four year old just needs to be stretch and saturate the data to extremes in Photoshop . :p: )

User avatar
geckzilla
Ocular Digitator
Posts: 9172
Joined: Wed Sep 12, 2007 12:42 pm
Location: Modesto, CA

Re: APOD: Two Rings for Asteroid Chariklo (2014 Apr 09)

Post by geckzilla » Wed Apr 09, 2014 7:11 am

Nitpicker wrote:(Or maybe a four year old just needs to be stretch and saturate the data to extremes in Photoshop . :p: )
Definitely not!
Today I was looking at HD141569's circumstellar disk, which looks like it requires an extra step. Comparing that image to the original data in the HLA, all the spikey glowy stuff coming off the star actually covers up the circumstellar disk. I presume what must be done is that a model of the point spread function and wings is used to subtract that out which will finally reveal the details obscured by the star. Imaging the asteroid might end up something like that, assuming the rings are big enough to be resolved.
Just call me "geck" because "zilla" is like a last name.

User avatar
Nitpicker
Inverse Square
Posts: 2692
Joined: Fri Sep 20, 2013 2:39 am
Location: S27 E153

Re: APOD: Two Rings for Asteroid Chariklo (2014 Apr 09)

Post by Nitpicker » Wed Apr 09, 2014 7:45 am

geckzilla wrote:
Nitpicker wrote:(Or maybe a four year old just needs to be stretch and saturate the data to extremes in Photoshop . :p: )
Definitely not!
Today I was looking at HD141569's circumstellar disk, which looks like it requires an extra step. Comparing that image to the original data in the HLA, all the spikey glowy stuff coming off the star actually covers up the circumstellar disk. I presume what must be done is that a model of the point spread function and wings is used to subtract that out which will finally reveal the details obscured by the star. Imaging the asteroid might end up something like that, assuming the rings are big enough to be resolved.
Well, I was being facetious, but I was imagining a method of detection which didn't require the asteroid to appear to pass in front of a star.

User avatar
JohnD
Tea Time, Guv! Cheerio!
Posts: 1508
Joined: Wed Feb 16, 2005 2:11 pm
Location: Lancaster, England

Re: APOD: Two Rings for Asteroid Chariklo (2014 Apr 09)

Post by JohnD » Wed Apr 09, 2014 8:02 am

Shurely shome mishtake?
The APOD shown is a nice selection of Greek tourist shots of the sky, in time lapse.
But nowt about asteroid rings.

John

User avatar
geckzilla
Ocular Digitator
Posts: 9172
Joined: Wed Sep 12, 2007 12:42 pm
Location: Modesto, CA

Re: APOD: Two Rings for Asteroid Chariklo (2014 Apr 09)

Post by geckzilla » Wed Apr 09, 2014 8:34 am

Nitpicker wrote:Well, I was being facetious, but I was imagining a method of detection which didn't require the asteroid to appear to pass in front of a star.
I know, and yeah, that's what I meant. The rings are faint and perhaps tenuous. The glare from the asteroid may cover them up.
Just call me "geck" because "zilla" is like a last name.

User avatar
Nitpicker
Inverse Square
Posts: 2692
Joined: Fri Sep 20, 2013 2:39 am
Location: S27 E153

Re: APOD: Two Rings for Asteroid Chariklo (2014 Apr 09)

Post by Nitpicker » Wed Apr 09, 2014 10:58 am

geckzilla wrote:
Nitpicker wrote:Well, I was being facetious, but I was imagining a method of detection which didn't require the asteroid to appear to pass in front of a star.
I know, and yeah, that's what I meant. The rings are faint and perhaps tenuous. The glare from the asteroid may cover them up.
I suppose the glare from the asteroid might indeed mask the rings. I would love to have a look through a telescope where a mag 18 object has too much glare. To be honest, I'd be happy enough to capture an image of the rings of Uranus. Even that seems far fetched to me at the moment.

CURRAHEE CHRIS
Science Officer
Posts: 105
Joined: Mon Sep 30, 2013 4:04 pm
Location: Mechanicsburg Pa.

Re: APOD: Two Rings for Asteroid Chariklo (2014 Apr 09)

Post by CURRAHEE CHRIS » Wed Apr 09, 2014 12:35 pm

Just so I have this straight- Chariklo is an asteroid?????? and it has rings around it???? Im assuming these rings are in orbit or some kind of motion around Chariklo then?

User avatar
neufer
Vacationer at Tralfamadore
Posts: 18805
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: Two Rings for Asteroid Chariklo (2014 Apr 09)

Post by neufer » Wed Apr 09, 2014 12:47 pm

CURRAHEE CHRIS wrote:
Just so I have this straight- Chariklo is an asteroid?????? and it has rings around it???? Im assuming these rings are in orbit or some kind of motion around Chariklo then?
You have it straight.

Nine rings were intended for Men, seven for Dwarves, five for the ice giants, four for Jupiter, three for the Elves, two for Chariklo, and one, the One Ring, for Sauron in Mount Doom.
Art Neuendorffer

Boomer12k
:---[===] *
Posts: 2691
Joined: Sun Apr 22, 2007 12:07 am

Re: APOD: Two Rings for Asteroid Chariklo (2014 Apr 09)

Post by Boomer12k » Wed Apr 09, 2014 1:23 pm

OK....COOL..... a blip, a dip, and a blip....

I wonder, are they smashed rocks, or ICE?????

:---[===] *

User avatar
Chris Peterson
Abominable Snowman
Posts: 16822
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Two Rings for Asteroid Chariklo (2014 Apr 09)

Post by Chris Peterson » Wed Apr 09, 2014 2:08 pm

geckzilla wrote:Imaging the asteroid might end up something like that, assuming the rings are big enough to be resolved.
The rings are 0.08 arcseconds across when the asteroid is at its closest, which is right on the hairy edge of HST resolution limit. But there are ground-based telescopes that have quite a bit higher resolution than Hubble.

As far as brightness, if we can image the system with the rings quite open, their reflecting area is about 1/8 that of the asteroid itself. Given that ring systems are often very high albedo, it's possible that we're receiving about the same amount of light from the rings as we are from the (probably dark) asteroid. So imaging might be feasible (and at 18 magnitude, the object is very bright, easily captured by small amateur telescopes, though not resolved by them).

An interesting experiment: with a large telescope, we could collect the spectrum of the object. This could be repeated in a decade or so, when the ring orientation had changed. That might allow us to see two separate spectra populations, one for the asteroid and the other for the rings.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

CURRAHEE CHRIS
Science Officer
Posts: 105
Joined: Mon Sep 30, 2013 4:04 pm
Location: Mechanicsburg Pa.

Re: APOD: Two Rings for Asteroid Chariklo (2014 Apr 09)

Post by CURRAHEE CHRIS » Wed Apr 09, 2014 2:13 pm

neufer wrote:
CURRAHEE CHRIS wrote:
Just so I have this straight- Chariklo is an asteroid?????? and it has rings around it???? Im assuming these rings are in orbit or some kind of motion around Chariklo then?
You have it straight.

Nine rings were intended for Men, seven for Dwarves, five for the ice giants, four for Jupiter, three for the Elves, two for Chariklo, and one, the One Ring, for Sauron in Mount Doom.
:lol2: :P

Good one!!! Thanks for the clarification. Always something new to be learned here on APOD. I would have never thought such a phenomenon could exist.

User avatar
geckzilla
Ocular Digitator
Posts: 9172
Joined: Wed Sep 12, 2007 12:42 pm
Location: Modesto, CA

Re: APOD: Two Rings for Asteroid Chariklo (2014 Apr 09)

Post by geckzilla » Wed Apr 09, 2014 3:04 pm

Chris Peterson wrote:The rings are 0.08 arcseconds across when the asteroid is at its closest, which is right on the hairy edge of HST resolution limit. But there are ground-based telescopes that have quite a bit higher resolution than Hubble.

As far as brightness, if we can image the system with the rings quite open, their reflecting area is about 1/8 that of the asteroid itself. Given that ring systems are often very high albedo, it's possible that we're receiving about the same amount of light from the rings as we are from the (probably dark) asteroid. So imaging might be feasible (and at 18 magnitude, the object is very bright, easily captured by small amateur telescopes, though not resolved by them).

An interesting experiment: with a large telescope, we could collect the spectrum of the object. This could be repeated in a decade or so, when the ring orientation had changed. That might allow us to see two separate spectra populations, one for the asteroid and the other for the rings.
James Webb? I know images of Uranus work well in infrared. I hope this asteroid ends up on the target list for JWST if it would result in a worthwhile image plus data.

With the Internet and online archives being made publicly available that experiment could happen whether anyone intends it to or not.
Just call me "geck" because "zilla" is like a last name.

User avatar
JohnD
Tea Time, Guv! Cheerio!
Posts: 1508
Joined: Wed Feb 16, 2005 2:11 pm
Location: Lancaster, England

Re: APOD: Two Rings for Asteroid Chariklo (2014 Apr 09)

Post by JohnD » Wed Apr 09, 2014 4:23 pm

APOD now showing: Something Completely Different - Chariklo animation.
What happened?

And is someone joking with APOD? See the link "computer simulations", which goes to:
http://www.macworksinc.net/Images/rand.jpg

John
Last edited by JohnD on Wed Apr 09, 2014 4:30 pm, edited 1 time in total.

User avatar
geckzilla
Ocular Digitator
Posts: 9172
Joined: Wed Sep 12, 2007 12:42 pm
Location: Modesto, CA

Re: APOD: Two Rings for Asteroid Chariklo (2014 Apr 09)

Post by geckzilla » Wed Apr 09, 2014 4:29 pm

JohnD wrote:APOD now showing: Something Completely Different - Chariklo animation.
What happened?
John
Sounds like a weird problem you've got. I never saw anything but the Chariklo animation.
Just call me "geck" because "zilla" is like a last name.

User avatar
JohnD
Tea Time, Guv! Cheerio!
Posts: 1508
Joined: Wed Feb 16, 2005 2:11 pm
Location: Lancaster, England

Re: APOD: Two Rings for Asteroid Chariklo (2014 Apr 09)

Post by JohnD » Wed Apr 09, 2014 5:02 pm

What do you see when you click on "computer simulations"?

User avatar
neufer
Vacationer at Tralfamadore
Posts: 18805
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: Two Rings for Asteroid Chariklo (2014 Apr 09)

Post by neufer » Wed Apr 09, 2014 5:12 pm

APOD Robot wrote:
http://en.wikipedia.org/wiki/Centaur_%28minor_planet%29 wrote: <<Centaurs are small Solar System bodies with a semi-major axis between those of the outer planets. They have unstable orbits that cross or have crossed the orbits of one or more of the giant planets, and have dynamic lifetimes of a few million years. It has been estimated that there are around 44,000 centaurs in the Solar System with diameters larger than 1 km.

http://upload.wikimedia.org/wikipedia/c ... rs.svg.png

Centaurs typically behave with characteristics of both asteroids & comets. Three centaurs have been found to display cometary comas: Chiron, 60558 Echeclus, and 166P/NEAT. Chiron & Echeclus are therefore classified as both asteroids & comets. Other centaurs such as 52872 Okyrhoe are suspected of showing cometary activity. Any centaur that is perturbed close enough to the Sun is expected to become a comet. They are named after the mythological beings that were a mixture of horse and human, centaurs.

The first centaur to be discovered was 944 Hidalgo in 1920. However, they were not recognized as a distinct population until the discovery of 2060 Chiron in 1977. The largest known centaur is 10199 Chariklo, which at 260 km in diameter is as big as a mid-sized main-belt asteroid, and is known to have a system of rings. It was discovered in 1997. However, the lost centaur, 1995 SN55, may be somewhat larger. No centaur has been photographed up close, although there is evidence that Saturn's moon Phoebe, imaged by the Cassini probe in 2004, may be a captured centaur. In addition, the Hubble Space Telescope has gleaned some information about the surface features of 8405 Asbolus.>>
http://en.wikipedia.org/wiki/10199_Chariklo wrote: <<10199 Chariklo (KARR-i-kloh or kə-RIK-loh) is the largest known "centaur" or minor planet orbiting between the gas giants. It orbits the Sun between Saturn and Uranus, grazing the inner orbit of Uranus (with a ~ 4:3 resonance). On 26 March 2014, astronomers announced the discovery of two rings nicknamed Oiapoque and Chuí, after two rivers that form the northern and southern coastal borders of Brazil, around Chariklo by observing a stellar occultation. Chariklo (discovered by James V. Scotti of the Spacewatch program on February 15, 1997) is named after the nymph Chariclo (Χαρικλώ, “graceful spinner”), the wife of Chiron and the daughter of Apollo.

Centaurs originated in the Kuiper belt and are in dynamically unstable orbits that will lead to ejection from the Solar System, an impact with a planet or the Sun, or transition into a short-period comet. The orbit of Chariklo is more stable than those of Nessus, Chiron, and Pholus and is estimated to have a long orbital half-life of about 10.3 Myr.>>
Art Neuendorffer

User avatar
Anthony Barreiro
Turtles all the way down
Posts: 793
Joined: Wed May 11, 2011 7:09 pm
Location: San Francisco, California, Turtle Island

Re: APOD: Two Rings for Asteroid Chariklo (2014 Apr 09)

Post by Anthony Barreiro » Wed Apr 09, 2014 6:27 pm

Chris Peterson wrote: ... (and at 18 magnitude, the object is very bright, easily captured by small amateur telescopes, though not resolved by them) ... .
Chris, your ideas of "very bright" and "small amateur telescopes" are very different from mine! Or maybe everything is different at 3000 meters elevation. Maybe a 200 mm aperture dobsonian telescope shipped from sea level will swell to 1000 mm aperture in the lower air pressure.
May all beings be happy, peaceful, and free.

User avatar
Anthony Barreiro
Turtles all the way down
Posts: 793
Joined: Wed May 11, 2011 7:09 pm
Location: San Francisco, California, Turtle Island

Re: APOD: Two Rings for Asteroid Chariklo (2014 Apr 09)

Post by Anthony Barreiro » Wed Apr 09, 2014 6:30 pm

This illustration shows Chariklo as roughly spherical. Would an asteroid of 250 km diameter be able to pull itself into a spherical shape? Would that make Chariklo a dwarf planet?
May all beings be happy, peaceful, and free.

User avatar
neufer
Vacationer at Tralfamadore
Posts: 18805
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: Two Rings for Asteroid Chariklo (2014 Apr 09)

Post by neufer » Wed Apr 09, 2014 6:50 pm

Anthony Barreiro wrote:
This illustration shows Chariklo as roughly spherical. Would an asteroid of 250 km diameter be able to pull itself into a spherical shape? Would that make Chariklo a dwarf planet?
  • Probably not.
http://en.wikipedia.org/wiki/Dwarf_planet#Size_and_mass wrote:
<<The lower size and mass limits of dwarf planets is determined by the requirements of achieving a hydrostatic equilibrium shape, but the size or mass at which an object attains this shape depends on its composition and thermal history. Empirical observations suggest that the lower limit will vary according to the composition and thermal history of the object. For a body made of rigid silicates, such as the stony asteroids, the transition to hydrostatic equilibrium should occur at a diameter of approximately 600 km and a mass of some 3.4×1020 kg. For a body made of less rigid water ice, the limit should be about 320 km and 1019 kg. Assuming that Methone's elongated shape reflects the balance between the tidal force exerted by Saturn and its own gravity, its diameter only 3 km suggests that it is composed of icy fluff. In the asteroid belt, Ceres is the only body that clearly surpasses the silicaceous limit (though it is actually a rocky–icy body), and its shape is an equilibrium spheroid. 2 Pallas and 4 Vesta, however, are rocky and are just below the limit. Pallas, at 525–560 km and 1.85–2.4×1020 kg, is "nearly round" but still somewhat irregular. Vesta, at 530 km and 2.6×1020 kg, deviates from an ellipsoid shape primarily due to a large impact basin at its pole.

Among icy bodies, the smallest thought to be in hydrostatic equilibrium when the concept of dwarf planet was being debated was Mimas, at 396 km and 3.75×1019 kg. The largest irregular body known in the outer Solar System is Proteus, nearly-but-not-quite round at 405–435 km and an assumed mass of ≈4.4×1019 kg. Bodies like Mimas may have had a warmer thermal history than Proteus, or their shape may have resolved after a collision. Neither body is pure ice as used to calculate the lowest limit, however, and Mike Brown suggested that the practical lower limit for an icy dwarf planet is likely to be somewhere under 400 km. There are about 100 TNOs currently estimated to be above this size. However, it has since been discovered that Mimas is not in hydrostatic equilibrium, and that its ellipsoidal shape is due to its past history, rather like the more extreme case of tiny Phoebe. The smallest Saturnian moon confirmed to be in hydrostatic equilibrium is Rhea, at 1,530 km, whereas the largest not in equilibrium is Iapetus, at 1,470 km. These findings have not been discussed in the context of dwarf planets, but Iapetus and Rhea are in the size range of Makemake (1,415–1,445 km) and larger than Haumea (1,180–1,310 km).>>
Art Neuendorffer

User avatar
Chris Peterson
Abominable Snowman
Posts: 16822
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Two Rings for Asteroid Chariklo (2014 Apr 09)

Post by Chris Peterson » Wed Apr 09, 2014 10:37 pm

Anthony Barreiro wrote:
Chris Peterson wrote: ... (and at 18 magnitude, the object is very bright, easily captured by small amateur telescopes, though not resolved by them) ... .
Chris, your ideas of "very bright" and "small amateur telescopes" are very different from mine! Or maybe everything is different at 3000 meters elevation. Maybe a 200 mm aperture dobsonian telescope shipped from sea level will swell to 1000 mm aperture in the lower air pressure.
When I say "captured" it means I'm talking about imaging. If I meant visually, I'd say "see" or something along those lines. Imaging a mag 18 point source is quite trivial with a small telescope and an electronic camera. At any elevation, and even under less than perfectly dark conditions.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

BDanielMayfield
Don't bring me down
Posts: 2524
Joined: Thu Aug 02, 2012 11:24 am
AKA: Bruce
Location: East Idaho

Re: APOD: Two Rings for Asteroid Chariklo (2014 Apr 09)

Post by BDanielMayfield » Wed Apr 09, 2014 10:46 pm

neufer wrote:
Anthony Barreiro wrote:
This illustration shows Chariklo as roughly spherical. Would an asteroid of 250 km diameter be able to pull itself into a spherical shape? Would that make Chariklo a dwarf planet?
Probably not.
So Chariklo (a potato with a side order of onion rings) would more accurately be classified as a minor planet, which is not a planet at all. Gota love antiquated astronomical nomenclature. :?

Bruce
Just as zero is not equal to infinity, everything coming from nothing is illogical.

User avatar
Nitpicker
Inverse Square
Posts: 2692
Joined: Fri Sep 20, 2013 2:39 am
Location: S27 E153

Re: APOD: Two Rings for Asteroid Chariklo (2014 Apr 09)

Post by Nitpicker » Wed Apr 09, 2014 10:50 pm

BDanielMayfield wrote:
neufer wrote:
Anthony Barreiro wrote:
This illustration shows Chariklo as roughly spherical. Would an asteroid of 250 km diameter be able to pull itself into a spherical shape? Would that make Chariklo a dwarf planet?
Probably not.
So Chariklo (a potato with a side order of onion rings) would more accurately be classified as a minor planet, which is not a planet at all. Gota love antiquated astronomical nomenclature. :?

Bruce
Not antiquated. Contemporary yet increasingly problematic.

User avatar
neufer
Vacationer at Tralfamadore
Posts: 18805
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: Two Rings for Asteroid Chariklo (2014 Apr 09)

Post by neufer » Thu Apr 10, 2014 12:30 am

neufer wrote:
Anthony Barreiro wrote:
This illustration shows Chariklo as roughly spherical. Would an asteroid of 250 km diameter be able to pull itself into a spherical shape? Would that make Chariklo a dwarf planet?
Probably not.
BDanielMayfield wrote:
So Chariklo (a potato with a side order of onion rings) would more accurately be classified as a minor planet, which is not a planet at all. Gota love antiquated astronomical nomenclature. :?
http://en.wikipedia.org/wiki/Centaur_%28minor_planet%29 wrote:
<<No centaur has been photographed up close, although there is evidence that Saturn's moon Phoebe may be a captured centaur.>>
http://en.wikipedia.org/wiki/Phoebe_%28moon%29 wrote:
:arrow: <<Phoebe (Greek: Φοίβη) is an irregular satellite of Saturn a little over 200 km in diameter. It is thought to be a captured planetesimal from the Kuiper belt.The Phoebe ring is one of the rings of Saturn. This ring is tilted 27 degrees from Saturn's equatorial plane (and the other rings). It extends from at least 128 to 207 times the radius of Saturn; Phoebe orbits the planet at an average distance of 215 Saturn radii. The ring is about 20 times as thick as the diameter of the planet. Since the ring's particles are presumed to have originated from micrometeoroid impacts on Phoebe, they should share its retrograde orbit, which is opposite to the orbital motion of the next inner moon, Iapetus. Inwardly migrating ring material would thus strike Iapetus's leading hemisphere, and is suspected to have triggered the processes that led to the two-tone coloration of that moon. Although very large, the ring is virtually invisible—it was discovered using NASA's infrared Spitzer Space Telescope.>>
Art Neuendorffer