Reopening the TNOs color controversy: Centaurs bimodality and TNOs unimodality (original) (raw)

A&A 410, L29-L32 (2003)

Letter to the Editor

1 LESIA, Observatoire de Paris, 5 Pl. Jules Janssen, 92195 Meudon Cedex, France e-mail: Nuno.Peixinho@obspm.fr; e-mail: Nuno.Peixinho,Alain.Doressoundiram,Antonella.Barucci@obspm.fr
2 CAAUL, Observatório Astronómico de Lisboa, Tapada da Ajuda, 1349-018 Lisboa, Portugal
3 Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany e-mail: hboehnha@mpia-hd.mpg.de
4 Astronomical Observatory of Kharkov National University, Sumskaya St. 35, Kharkov 61022, Ukraine e-mail: irina@astron.kharkov.ua

Corresponding author: N. Peixinho, Nuno.Peixinho@obspm.fr

Received: 8 August 2003
Accepted: 12 September 2003

Abstract

We revisit the Trans–Neptunian Objects (TNOs) color controversy allegedly solved by Tegler & Romanishin (2003). We debate the statistical approach of the quoted work and discuss why it can not draw the claimed conclusions, and reanalyze their data sample with a more adequate statistical test. We find evidence for the existence of two color groups among the Centaurs. Therefore, mixing both centaurs and TNOs populations lead to the erroneous conclusion of a global bimodality, while there is no evidence for two color groups in the TNOs population alone. We use quasi–simultaneous visible color measurements published for 20 centaurs (corresponding to about half of the identified objects of this class), and conclude on the existence of two groups. With the surface evolution model of Delsanti et al. (2003). we discuss how the existence of two groups of Centaurs may be compatible with a continuous TNOs color distribution.

Key words: Kuiper Belt / methods: statistical