Observatory Logo


From: TerryMoselaol.com
Date: Fri, 29 Jul 2005 16:33:14 EDT
Subject: Pluto's little brother....

Hi all,
 
It's great to have some of the world's leading experts in certain subjects  
here to keep us up to date!
 
I've just got the following hot news from Prof Alan Fitzsimmons at  QUB, 
indicating that the object is likely to be smaller than Pluto. 
 
But it's equally interesting that it has been found to have a Moon, and  that 
some of the better equipped Irish amateurs might be able measure  the light 
curve, or at least detect the variation....
..............................................................................
...................................
"Hi Terry,

A very bright TNO was announced earlier today by the MPC  and given the 
designation 2003 EL61. This is the object at the positions  you listed in your 
earlier E-mail. It has already been studied by MIke  Brown and Colleagues, and 
this team has already found these important  details.

1. It has a moon, seen at Keck with adaptive optics and a laser  guide star 
system. The moon has an orbital period of 49 days and orbits at a  distance of  
49,500km from the object. This gives the mass as approximately  32% that of 
Pluto.

2. It has a rotation period of only 3.89 hours as seen  from a double- peaked 
lightcurve.
Also, the amplitude of the lightcurve  implies an axial ratio of 1.4 -  this 
object is nowhere
near spherical  (albedo markings are unlikely to be the cause as the 
lightcurve is  very
symmetrical). I would think that this lightcurve might be measurable by  
amateurs.

3. Spectra show clear signs of water ice on the  surface.

4. Spitzer was used to observe it, and word is it didn't see it.  If so, the 
albedo will be large
and it probably has a smaller diameter  than Pluto.

All the  best,
Alan."
..............................................................................
...................................
 
Clear skies,
 
Terry Moseley

---------

Last Revised: 2005 August 1st
WWW contact:webmaster@arm.ac.uk
Go to HOME PageHome Page