The enigmatic brown dwarf candidate [KG2001] 102 in the Chamaeleon I cloud: Is it a multiple system?^*

¹ Istituto Astrofisica Spaziale e Fisica Cosmica, CNR, via fosso del cavaliere 100, 00133 Roma, Italy e-mail: persi@rm.iasf.cnr.it
² Instituto de Astronomía, UNAM, Apartado Postal 877, 22830 Ensenada, BC Mexico
³ Observatorio Astronómico de Córdoba, Laprida 854, 5000 Córdoba, Argentina
⁴ Las Campanas Observatory, Carnegie Institution of Washington, Casilla 601, La Serena, Chile

Received: 14 June 2004
Accepted: 11 October 2004

Abstract

We present deep IJHK_s and H₂ images of a region in the Chamaeleon I dark cloud containing the very low-mass young object [KG2001]102, in an attempt to search for multiplicity and molecular outflow in the vicinity of this object. No low-velocity shocked structures were detected in our H₂ image. The broad-band and narrow-band images show that [KG2001]102 is composed of four objects within a radius of ∼. The brightest component [KG2001]102 A shows near-IR excess emission and its mass is estimated to be in the range 33 to 55 M_Jup, depending on which model is adopted. Red spectra were obtained of the two fainter components B and C. The spectrum of the former suggests a K7V spectral type while the spectrum of component C is too noisy to allow a reliable classification but rules out a late M-type. The three faint components (B, C and D) have IJHK colors that suggest a much later spectral type, with extinctions similar to other members of the cloud. The computed probability of randomly finding a pair of field stars like [KG2001]102 AB is while for a triple optical system like [KG2001]102 ABC, it would be and more than an order of magnitude lower for finding a quadruple system like this by chance projection.