Sunday, February 19, 2012

Unusual Minor Planet 2011 YU75

This unusual minor planet was discovered by the Spacewatch sky survey on 2011, Dec. 26. It moves along a very eccentric orbit (perihelion close to Mars, aphelion nearly 3 AU away from Saturn). Currently it's about 1 AU from Earth and 2 AU from the Sun, approaching its perihelion, scheduled for the end of April 2012 (q= 1.7 AU). Since it moves along a nice comet-like track (a= 7.5 AU, e= 0.77, Incl.= 16.7 deg), we decided to insert it in our wish-list of interesting targets, in order to check if it's going to develope any perceptible sign of cometary activity (coma and/or tail) while approaching the Sun.

On 2012, Feb 17.4 we aimed the "Faulkes Telescope South" 2.0-m f/10.0 Ritchey-Chretien + CCD at Siding Spring (Australia) to this target, and collected on it twelve R-filtered exposures, 30-seconds each. Stacking these images through "Astrometrica" along the expected proper motion of 2011 YU75, we get a nice starlike object (magnitude ~19) at its expected position. Its FWHM was the same of the nearby field stars (about 1.2-arcsec) and no traces of coma/tail was visible to us, in spite of several image processing routines we applied on it. So we can conclude that, at least through the analysis of the images we collected, at this time 2011 YU75 shows no detectable outgassing activity.  Below you can see our follow-up image. Click on it so see a larger version.

by Nick Howes, Giovanni Sostero and Ernesto Guido

No comments: