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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents



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ID: 225819.0, MPI für Astronomie / Publikationen_mpia
The brown dwarf population in the Chamaeleon I cloud
Authors:López Martí, B.; Eislöffel, J.; Scholz, A.; Mundt, R.
Date of Publication (YYYY-MM-DD):2004
Title of Journal:Astronomy and Astrophysics
Volume:416
Start Page:555
End Page:576
Review Status:not specified
Audience:Not Specified
Abstract / Description:We present the results of a multiband survey
for Brown dwarfs in the <ASTROBJ>Chamaeleon
I</ASTROBJ> dark cloud with the Wide Field Imager
(WFI) camera at the ESO/MPG 2.2-m telescope on La
Silla (Chile). The survey has revealed a
substantial population of Brown dwarfs in this
southern star-forming region. Candidates were
selected from R, I and H‚‚alpha; imaging
observations. We also observed in two medium-band
filters,M 855 and M 915, for spectral type
determination. The former filter covers a
wavelength range containing spectral features
characteristic of M-dwarfs, while the latter lies
in a relatively featureless wavelength region
for these late-type objects. A correlation was
found between spectral type and (M 855-M 915)
colour index for mid- to late M-type objects and
early L-type dwarfs. With this method, we
identify most of our object candidates as being
of spectral type M 5 or later. Our results show
that there is no strong drop in the number of
objects for the latest spectral types, hence
Brown dwarfs may be as abundant as low-mass
stars in this region. Also, both kind of objects
have a similar spatial distribution. We derive an
index ‚‚alpha; = 0.6 ‚‚plusmn; 0.1 of the mass
function in this region of dispersed star
formation, in good agreement with the values
obtained in other star forming regions and young
clusters. Some of the Brown dwarfs have strong
H‚‚alpha; emission, suggesting mass accretion.
For objects with published infrared photometry,
we find that strong H‚‚alpha; emission is related
to a mid-infrared excess, indicative of the
existence of a circumstellar disk.
Free Keywords:stars: low-mass; Brown dwarfs; stars:
; pre-main sequence; stars: formation; stars:
; luminosity function; mass function; stars:
; circumstellar matter
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
External Affiliations:Universitat de Val‚‚egrave;ncia, Edifici
d'Instituts d'Investigaci‚‚oacute;,
Pol‚‚iacute;gon La Coma, 46980 Paterna, Spain;
Th‚‚uuml;ringer Landessternwarte, Sternwarte 5,
07778 Tautenburg, Germany
<EMAIL>belen.lopez-marti@uv.es</EMAIL>),
AB(Th‚‚uuml;ringer Landessternwarte, Sternwarte
5, 07778 Tautenburg, Germany
<EMAIL>jochen@tls-tautenburg.de</EMAIL>),
AC(Th‚‚uuml;ringer Landessternwarte, Sternwarte
5, 07778 Tautenburg, Germany
<EMAIL>scholz@tls-tautenburg.de</EMAIL>),
AD(Max-Planck-Institut f‚‚uuml;r Astronomie,
K‚‚ouml;nigstuhl 17, 69117 Heidelberg, Germany
<EMAIL>mundt@mpia-hd.mpg.de</EMAIL>)
Identifiers:URL:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bi... [ID No:1]
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