Proto-brown dwarfs. 2: Results in the Ophiuchus and Taurus moleculra clouds

Abstract

view Abstract Citations (17) References (33) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Proto--Brown Dwarfs. II. Results in the Ophiuchus and Taurus Molecular Clouds Pound, Marc W. ; Blitz, Leo Abstract We expand our proto-brown dwarf search to include two nearby star-forming regions in the Ophiuchus and Taurus molecular clouds. In both molecular line and continuum searches in the Ophiuchus B and Barnard 18 (in Taurus) star-forming regions, we find no clear-cut evidence of any proto-brown dwarfs. This lack of proto-brown dwarfs is surprising; even if the initial mass function (IMF) (given by dN/dM proportional to M-alpha) were flat (alpha = 1), we would expect to have found approximately 10 objects. We do find, however, a few candidate objects near our detection limit (approximately 0.02 solar mass) which deserve further scrutiny. We find 21 gravitationally bound clumps distributed in mass with a spectral index alpha = 1.1 +/- 0.2. However, there are fewer low-mass clumps (approximately less than 0.1 solar mass) than would be expected from extrapolation of any reasonable mass function, including the well-known giant molecular cloud clump mass spectrum. If the IMF follows the clump mass spectrum below 0.08 solar mass, as it does at higher masses, our results in Oph B imply that, unless some undetermined process causes the production of many more low-mass clumps, the IMF is falling at masses below 0.08 solar mass, even if all our candidate objects turn out to be true proto-brown dwarfs. This work presents evidence that there is a mass range (0.1-0.25 solar mass) where the molecular cloud clump mass spectrum has the same slope stellar IMF (alpha approximately 1). This is an indication that there is indeed a direct relationship between clump mass and subsequent stellar mass and subsequent stellar mass at the scale of a few tenths of a solar mass. Publication: The Astrophysical Journal Pub Date: May 1995 DOI: 10.1086/175602 Bibcode: 1995ApJ...444..270P Keywords: Brown Dwarf Stars; Clumps; Interstellar Matter; Molecular Clouds; Stellar Mass; Astronomical Maps; Emission Spectra; Mass Spectra; Molecular Spectra; Star Formation; Astronomy; ISM: CLOUDS; STARS: LOW-MASS; BROWN DWARFS; STARS: LUMINOSITY FUNCTION; MASS FUNCTION full text sources ADS | data products SIMBAD (33) Related Materials (1) Part 1: 1993ApJ...418..328P