Name: Daniela Lazzaro

Institution: MCT / Observatorio Nacional

e-mail: lazzaro(no-spam)on.br

Partner Contry: BRA

Science Meeting: Yes

User Meeting: Yes

NGO Staff Meeting: None Selected

Presentation: Yes

Format: Oral

Title: Gemini observations of a very unstable TNO

Co-author: A. Alvarez-Candal D. Jones I.P. Williams M. Melita

Co-authors' Institutions: Observatorio Nacional, Brasl Astronomy Unit, Queen Mary, University of London, UK Astronomy Unit, Queen Mary, University of London, UK Instituto de Astronomia y Fisica del Espacio, Argentina

Abstract:

The physical surface properties of a Trans-Neptunian Object is believed to be mainly the result of interplay between irradiation from different kinds of cosmic rays and its collisional history. Objects recently resurfaced by collisions will very likely have physical properties very different from those of the bulk population. In particular, pristine ices from the interior are expected to be present on the surface. A possible way to identify a candidate to have suffered a major collision is by investigating the lifetime of the orbit near its present location. If the lifetime is very short, a physical encounter is a possible way by which the TNO has evolved into such a short lived orbit. In particular, we have studied the case of (59358) 1999CL158, the known trans-Neptunian object with the most chaotic orbit in the Classical Belt. By means of orbital numerical integrations, we estimate that (59358) 1999CL158 has resided near its location for some 10 Myr. We have obtained a near-infrared spectrum of (59358) 1999CL158 using the near infrared imager and spectrograph, NIRI, at Gemini North 8-m telescope in the region between 1.43 - 1.96 microns. These are NIR observations of the faintest, and the smallest TNO observed at present. We searched for ice-bands, such as CH₄ and H₂O, having found evidence of the first. The detection of methane is an evidence of a young surface, therefore we conclude that it is likely that (59358) 1999CL158 has suffered recent collisions. Correspondingly, methane-ice must be an abundant component of this object.