A study of Trans-Neptunian object 55636 (2002 TX)

¹ Instituto de Astrofísica de Andalucía, CSIC, Apt 3004, 18080 Granada, Spain
² I.R.A.M., 300 rue de la Piscine, 38406 St-Martin d'Hères Cedex, France
³ Observatoire de Paris, 5 place J. Jansen, 92195 Meudon, France
⁴ Observatoire de Besançon, BP 1615, 25010 Besançon Cedex, France
⁵ Laboratoire d'Astrophysique de Marseille, Traverse du Siphon, BP 8, 13376 Marseille Cedex 12, France

Corresponding author: J. L. Ortiz, ortiz@iaa.es

Received: 13 October 2003
Accepted: 3 March 2004

Abstract

We report on physical properties of the bright Trans-Neptunian Object 2003 TX₃₀₀ based on a large set of observations taken in different wavelength ranges. Broad band CCD observations aimed at studying the short-term rotational variability show a low amplitude periodic signal of  h. We cannot yet determine whether the lightcurve is single-peaked (i.e. the rotation period would be 7.89 h) or double-peaked (i.e. the actual spin period would be 15.78 h). From a sinusoidal fit, the peak to peak amplitude of the brightness changes is  mag. If the brightness changes are due to irregular shape, this amplitude implies a minimum axial ratio of 1.09. BVRI photometry indicates similar colors as other large Kuiper Belt members, with , , and . Thermal observations at 250 GHz (1.2 mm) result in no confident detection of the body, with a measured flux of  mJy. Combining all the data and using the same thermophysical model as in Lellouch et al. ([CITE]) we find (at a 3-σ confidence level) a lower limit for the geometric albedo () and an upper limit for the size of this object ( 1110 km). A more relaxed 2-σ confidence level implies a diameter  km and an albedo , which is significantly higher than the typical 0.04 cometary value and also higher than that of Varuna.