MAPPING THE SHORES OF THE BROWN DWARF DESERT. II. MULTIPLE STAR FORMATION IN TAURUS-AURIGA

Journal Article · Sun Apr 10 04:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/731/1/8· OSTI ID:21574796

Kraus, Adam L ^[1]; Ireland, Michael J ^[2]; Martinache, Frantz ^[3]; Hillenbrand, Lynne A ^[4]

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1. Institute for Astronomy, University of Hawaii, 2680 Woodlawn Dr., Honolulu, HI 96822 (United States)
2. Sydney Institute for Astronomy (SIfA), School of Physics, University of Sydney, NSW 2006 (Australia)
3. National Astronomical Observatory of Japan, Subaru Telescope, Hilo, HI 96720 (United States)
4. Department of Astrophysics, California Institute of Technology, MC 249-17, Pasadena, CA 91125 (United States)

We have conducted a high-resolution imaging study of the Taurus-Auriga star-forming region in order to characterize the primordial outcome of multiple star formation and the extent of the brown dwarf desert. Our survey identified 16 new binary companions to primary stars with masses of 0.25-2.5 M{sub sun}, raising the total number of binary pairs (including components of high-order multiples) with separations of 3-5000 AU to 90. We find that {approx}2/3-3/4 of all Taurus members are multiple systems of two or more stars, while the other {approx}1/4-1/3 appear to have formed as single stars; the distribution of high-order multiplicity suggests that fragmentation into a wide binary has no impact on the subsequent probability that either component will fragment again. The separation distribution for solar-type stars (0.7-2.5 M{sub sun}) is nearly log-flat over separations of 3-5000 AU, but lower-mass stars (0.25-0.7 M{sub sun}) show a paucity of binary companions with separations of {approx}>200 AU. Across this full mass range, companion masses are well described with a linear-flat function; all system mass ratios (q = M{sub B} /M{sub A} ) are equally probable, apparently including substellar companions. Our results are broadly consistent with the two expected modes of binary formation (free-fall fragmentation on large scales and disk fragmentation on small scales), but the distributions provide some clues as to the epochs at which the companions are likely to form.

• OSTI ID: 21574796
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 731; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BINARY STARS
DWARF STARS
EVOLUTION
FRAGMENTATION
MAPPING
STAR EVOLUTION
STARS