Rotations and densities of trans-Neptunian objects

Trans-Neptunian objects (TNOs) represent a new frontier in the study of our Solar System. In particular, the investigation of their rotational properties can provide important hints about their internal structure and collisional evolution. Aims: We expand the limited sample of TNOs with known rotation rates, and improve the knowledge of the physical nature of these bodies. Methods: We carried out photometric observations of 5 TNOs (144897 2004 UX{10}, 145451 2005 RM{43}, 145453 2005 RR{43}, 2003 UZ{117}, and 2003 UZ{413}) using the New Technology Telescope of the European Southern Observatory. Results: We determined the spin rates of four targets, while only an estimation of the period was possible for 2003 UZ{117}. Conclusions: From the computed rotational periods and the obtained light curve amplitudes of four TNOs, we derived the lower limit to their axis ratio a/b, and hence estimated their density. Combining our new results with literature data, we investigated the density statistics of the small bodies of the outer Solar System. Based on observations carried out at the European Southern Observatory (ESO), La Silla, Chile. ESO Large Programme 178.C-0036. Photometric light curves are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/508/451