APOD: Ice Ring around Nearby Star Fomalhaut (2017 Oct 03)

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APOD: Ice Ring around Nearby Star Fomalhaut (2017 Oct 03)

Postby APOD Robot » Tue Oct 03, 2017 4:05 am

Image Ice Ring around Nearby Star Fomalhaut

Explanation: Why is there a large ice ring around Fomalhaut? This interesting star -- easily visible in the night sky -- lies only about 25 light-years away and is known to be orbited by at least one planet, Dagon, as well as several inner dust disks. More intriguing, perhaps, is an outer ring, first discovered about 20 years ago, that has an unusually sharp inner boundary. The featured recent image by the Atacama Large Millimeter Array (ALMA) shows this outer ring with complete and unprecedented detail -- in pink -- superposed on a Hubble image of the Fomalhaut system in blue. A leading theory holds that this ring resulted from numerous violent collisions involving icy comets and planetesimals, the component objects of planets, while the ring boundaries are caused by the gravity of yet unseen planets. If correct, any interior planets in the Fomalhaut system are likely being continually pelted by large meteors and comets -- an onslaught last seen in our own planetary system four billion years ago in an episode called the Late Heavy Bombardment.

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Re: APOD: Ice Ring around Nearby Star Fomalhaut (2017 Oct 03)

Postby ta152h0 » Tue Oct 03, 2017 8:19 am

Here is looking at you
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Re: APOD: Ice Ring around Nearby Star Fomalhaut (2017 Oct 03)

Postby orin stepanek » Tue Oct 03, 2017 11:33 am

Could the Ice Ring be on the edge of the Goldilocks Zone? :?
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Re: APOD: Ice Ring around Nearby Star Fomalhaut (2017 Oct 03)

Postby karenkumor@gmail.com » Tue Oct 03, 2017 12:17 pm

A question. I do not understand the black center with the glowing center inside that. Is that a photo technique to obtain an image of the ice ring?

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Re: APOD: Ice Ring around Nearby Star Fomalhaut (2017 Oct 03)

Postby neufer » Tue Oct 03, 2017 12:25 pm

orin stepanek wrote:
Could the Ice Ring be on the edge of the Goldilocks Zone? :?

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Re: APOD: Ice Ring around Nearby Star Fomalhaut (2017 Oct 03)

Postby neufer » Tue Oct 03, 2017 12:26 pm

karenkumor@gmail.com wrote:
I do not understand the black center with the glowing center inside that.
Is that a photo technique to obtain an image of the ice ring?

Yes.
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Re: APOD: Ice Ring around Nearby Star Fomalhaut (2017 Oct 03)

Postby Case » Tue Oct 03, 2017 1:05 pm

The center of the debris ring, the center of the occulting disk, and the center of the star image do not align. The universe is under no obligation to make sense to me (NDT) :wink: , but what could cause it to be off-center? Would the influence of the B and C star, or the planets in the system be enough to shape the debris ring that way? On a different note, is the oval shape of the star itself a result of the imaging system?

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Re: APOD: Ice Ring around Nearby Star Fomalhaut (2017 Oct 03)

Postby Fred the Cat » Tue Oct 03, 2017 1:16 pm

Oh, I get it. This must be the early, light bombardment. :idea:

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Re: APOD: Ice Ring around Nearby Star Fomalhaut (2017 Oct 03)

Postby Chris Peterson » Tue Oct 03, 2017 1:26 pm

Case wrote:The center of the debris ring, the center of the occulting disk, and the center of the star image do not align. The universe is under no obligation to make sense to me (NDT) :wink: , but what could cause it to be off-center?

The "ring" is eccentric (e = 0.12). So the star lies at one focus of an ellipse, not the center.

On a different note, is the oval shape of the star itself a result of the imaging system?

The star is unresolved, so yes, its shape is an artifact.
Chris

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Re: APOD: Ice Ring around Nearby Star Fomalhaut (2017 Oct 03)

Postby bystander » Tue Oct 03, 2017 2:18 pm

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Re: APOD: Ice Ring around Nearby Star Fomalhaut (2017 Oct 03)

Postby Roberto Molteni » Tue Oct 03, 2017 2:31 pm

And I presume that the radial stripes in the background image (blue, the one from Hubble) are also an imaging artifact, right?

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Re: APOD: Ice Ring around Nearby Star Fomalhaut (2017 Oct 03)

Postby Chris Peterson » Tue Oct 03, 2017 2:36 pm

Roberto Molteni wrote:And I presume that the radial stripes in the background image (blue, the one from Hubble) are also an imaging artifact, right?

Yes. Scatter from the optical surfaces.
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Re: APOD: Ice Ring around Nearby Star Fomalhaut (2017 Oct 03)

Postby Roberto Molteni » Tue Oct 03, 2017 2:42 pm

And, Chris Peterson, how do we know / determine the REAL elongation of the ellipses (not the observation one caused by the inclination of its orbital plane with respect to our line of sight)? In fact by the offset of the focus (Kepler's Law), or is there an independent way to verify it? (Such as e.g. Doppler effect at the two opposite extremities of the rotating ring).

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Re: APOD: Ice Ring around Nearby Star Fomalhaut (2017 Oct 03)

Postby Case » Tue Oct 03, 2017 3:04 pm

Chris Peterson wrote:
Case wrote:The center of the debris ring, the center of the occulting disk, and the center of the star image do not align. What could cause it to be off-center?
The "ring" is eccentric (e = 0.12). So the star lies at one focus of an ellipse, not the center.
Thanks, I get (the stability of) elliptical orbits, but I was wondering how such high eccentricity could come to be. Intuitively, I would expect spinning protoplanetary stuff to get more and more circular in its orbit. Perhaps an equilibrium is reached before things get close to circular?

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Re: APOD: Ice Ring around Nearby Star Fomalhaut (2017 Oct 03)

Postby Chris Peterson » Tue Oct 03, 2017 3:14 pm

Case wrote:
Chris Peterson wrote:
Case wrote:The center of the debris ring, the center of the occulting disk, and the center of the star image do not align. What could cause it to be off-center?
The "ring" is eccentric (e = 0.12). So the star lies at one focus of an ellipse, not the center.
Thanks, I get (the stability of) elliptical orbits, but I was wondering how such high eccentricity could come to be. Intuitively, I would expect spinning protoplanetary stuff to get more and more circular in its orbit. Perhaps an equilibrium is reached before things get close to circular?

I don't know. That's the sort of question best answered with modeling. But eccentricities can be maintained by resonances, and we might expect such resonances in a multiple star system.
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Re: APOD: Ice Ring around Nearby Star Fomalhaut (2017 Oct 03)

Postby sillyworm2 » Tue Oct 03, 2017 3:56 pm

Interesting information! A probe please....

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Re: APOD: Ice Ring around Nearby Star Fomalhaut (2017 Oct 03)

Postby Boomer12k » Wed Oct 04, 2017 2:01 am

Interesting...and great image... and since our own system has elliptical orbits...why not expect them elsewhere?

Their version of an Ort Cloud or Asteroid belt? A Saturn like Ice Ring of Comets?

T'would seem to be a lot of them. :shock:

Might be too much of a "shooting gallery" ....
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Re: APOD: Ice Ring around Nearby Star Fomalhaut (2017 Oct 03)

Postby neufer » Wed Oct 04, 2017 3:24 pm

Boomer12k wrote:
Interesting...and great image... and since our own system has elliptical orbits...why not expect them elsewhere?

Might be too much of a "shooting gallery" ....

A ring usually implies the ongoing collisions of a "shooting gallery."

Such chaos tends to be inconsistent with a well defined elliptical orbit.
Art Neuendorffer


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