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Multiplicity, Kinematics, and Rotation Rates of Very Young Brown Dwarfs in Cha I

Published online by Cambridge University Press:  26 May 2016

Viki Joergens ,
Ralph Neuhäuser ,
Eike W. Guenther ,
Matilde Fernández  and
Fernando Comerón
Viki Joergens
Affiliation:
Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstr. 1, D-85748 Garching, Germany
Ralph Neuhäuser
Affiliation:
Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstr. 1, D-85748 Garching, Germany
Eike W. Guenther
Affiliation:
Thüringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg, Germany
Matilde Fernández
Affiliation:
Instituto de Astrofísica de Andalucía (CSIC), Apdo. 3004, E-18080 Granada, Spain
Fernando Comerón
Affiliation:
European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching, Germany

Abstract

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We have studied twelve very young (1–5 Myr) bona fide and candidate brown dwarfs in the Cha I star forming region in terms of their kinematic properties, the occurrence of multiple systems among them as well as their rotational characteristics. Based on high-resolution spectra taken with UVES at the VLT (8.2 m), radial and rotational velocities have been measured. A kinematic study of the sample showed that their radial velocity dispersion is relatively small suggesting that they are not ejected during their formation as proposed in recent formation scenarios. By means of time-resolved UVES spectra, a radial velocity survey for close companions to the targets was conducted. The radial velocities of the targets turned out to be rather constant setting upper limits for the mass M2 sin i of possible companions to 0.1 MJup – 2 MJup. These findings hint at a rather low (≤ 10%) multiplicity fraction of the studied brown dwarfs. Furthermore, a photometric monitoring campaign of the targets yielded the determination of rotational periods for three brown dwarf candidates in the range of 2.2 to 3.4 days. These are the first rotational periods for very young brown dwarfs and among the first for brown dwarfs at all.

Type
Part 6. Searches for Substellar Companions
Information
Symposium - International Astronomical Union , Volume 211: Brown Dwarfs , 2003 , pp. 233 - 240
Copyright
Copyright © Astronomical Society of the Pacific 2001 

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