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Second Moon Around 2003 El61, Santa / Rudolph / ?
SigurRosFan
post Nov 30 2005, 12:59 PM
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http://www.gps.caltech.edu/~mbrown/2003EL61/#moon - The moons of 2003 EL61


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Omega
post Nov 30 2005, 03:48 PM
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QUOTE (SigurRosFan @ Nov 30 2005, 06:59 AM)


Fascinating. smile.gif A very informative article. Football shaped, huh? Too bad, though, about the background color (ugh). Certainly whets one's appetite for the Kuiper Belt...
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tedstryk
post Dec 2 2005, 02:30 PM
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QUOTE (Omega @ Nov 30 2005, 03:48 PM)
Fascinating.  smile.gif  A very informative article.  Football shaped, huh?  Too bad, though, about the background color (ugh).  Certainly whets one's appetite for the Kuiper Belt...
*


Somehow I don't buy the football shape. I strongly suspect that this is some sort of contact binary.


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tfisher
post Dec 2 2005, 04:59 PM
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QUOTE (tedstryk @ Dec 2 2005, 10:30 AM)
Somehow I don't buy the football shape. 
*


Why not? Just because nothing in the inner solar system looks that way? This wouldn't be the first astrophysical example of an object forced to a strongly elliptical shape by its spin. Take for example the star Archenar.
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ljk4-1
post Dec 2 2005, 05:29 PM
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QUOTE (tfisher @ Dec 2 2005, 11:59 AM)
Why not?  Just because nothing in the inner solar system looks that way?  This wouldn't be the first astrophysical example of an object forced to a strongly elliptical shape by its spin.  Take for example the star Archenar.
*


Also the star Regulus in Leo the Lion:

http://www.universetoday.com/am/publish/eg...ng.html?2112005

And there are cigar-shaped planetoids, such as Geographos, which actually looks more like a deflated football to me:

http://en.wikipedia.org/wiki/Geographos


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Bob Shaw
post Dec 3 2005, 12:08 AM
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QUOTE (Omega @ Nov 30 2005, 04:48 PM)
Fascinating.  smile.gif  A very informative article.  Football shaped, huh?  Too bad, though, about the background color (ugh).  Certainly whets one's appetite for the Kuiper Belt...
*


'Football-shaped' - I thought footballs were, er, *round*.

Or do you mean shaped like a Rugby ball?

(ducks and runs)

Bob Shaw


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mars loon
post Dec 3 2005, 02:31 PM
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QUOTE (Bob Shaw @ Dec 3 2005, 12:08 AM)
'Football-shaped' - I thought footballs were, er, *round*.

Or do you mean shaped like a Rugby ball?

(ducks and runs)

Bob Shaw
*

American Footballs are elliptical in shape.

SigurRosFan: Anyway this is quite fascinating, thanks for posting this excellent article. presumeably there is no photographic evidence for the elliptical shape.
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SigurRosFan
post Jan 25 2006, 01:47 PM
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New Astrophysics Paper:

http://fr.arxiv.org/abs/astro-ph/0601534

Water Ice on the Satellite (Rudolph) of Kuiper Belt Object 2003 EL61

--- We have obtained a near infrared spectrum of the brightest satellite [note: nicknamed Rudolph] of the large Kuiper Belt Object, 2003 EL61. The spectrum has absorption features at 1.5 and 2.0 microns, indicating that water ice is present on the surface. We find that the satellite's absorption lines are much deeper than water ice features typically found on Kuiper Belt Objects. We argue that the unusual spectrum indicates that the satellite was likely formed by impact and not by capture. ---


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SFJCody
post Jan 30 2006, 06:04 PM
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The Surface of 2003EL61 in the Near Infrared

http://arxiv.org/abs/astro-ph/0601618
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SigurRosFan
post May 1 2006, 08:11 PM
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2003 EL61's shape:


- http://www.gps.caltech.edu/~mbrown/2003EL61/

New facts

Equator diameter: 2,200 km

Pole diameter: 1,100 km

Rotation: 3 hours, 54 minutes

Mass: 3.9^21 kg

Density: 3,000 kg/m

Inner Moon = Distance: 39,300 km, Orbit: 34.1 days

Outer Moon = Distance: 49,100 km, Orbit: 49.1 days, Eccentricity: 0.048


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tasp
post May 1 2006, 08:51 PM
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Hypnotic!

blink.gif
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TritonAntares
post May 5 2006, 09:46 PM
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QUOTE (SigurRosFan @ May 1 2006, 09:11 PM) *
New facts:

Equator diameter: 2,200 km

Pole diameter: 1,100 km

Rotation: 3 hours, 54 minutes
I could bet...
... this is a close binary. wink.gif
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alan
post May 6 2006, 02:11 AM
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That was my first thought too, but it appears to have been ruled out.
QUOTE
Another possibility is that 2003 EL61 is a binary (making 2003 EL61 a tertiary system when we
include the co-orbiting satellite). In this case the mutual eclipses of the close, co-orbiting pair
cause the light curve variations. But Leone et al (1984) show that such a binary configuration is
unlikely if the light curve amplitude is small and the rotational velocity is high, as is the case for
2003 EL61. They tabulate approximate equilibrium solutions assuming the co-orbiting bodies are
homogenous and strengthless, but of unequal mass. In this case each body takes the shape of a
triaxial ellipsoid distorted by its own rotation and by the gravity of the other body. With these
assumptions, and given the short rotation period we observe, there is no stable solution for ρ <
5000 kg m-3. This clearly rules out a contact binary.

http://arxiv.org/ftp/astro-ph/papers/0509/0509401.pdf
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TritonAntares
post May 6 2006, 11:59 AM
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Ok.
But a very strange object with this two given axis 2.200 x 1.100 km (not 220 x 110 km !)... huh.gif
How can this still be stable from the begin of the solar system?
What causes the highspeed rotation and where is the driving energy from?
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Decepticon
post May 8 2006, 10:02 PM
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We need another Horizon Mission!

SO far away and so Dam interesting. smile.gif
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