Article (Scientific journals)
Binary Formation Mechanisms: Constraints from the Companion Mass Ratio Distribution
Reggiani, Maddalena; Meyer, Michael R.
2011In Astrophysical Journal, 738
Peer Reviewed verified by ORBi
 

Files


Full Text
Reggiani_2011_ApJ.pdf
Publisher postprint (363.57 kB)
Download

All documents in ORBi are protected by a user license.

Send to



Details



Keywords :
binaries: general; open clusters and associations: general; stars: formation; stars: luminosity function; mass function; stars: pre-main sequence
Abstract :
[en] We present a statistical comparison of the mass ratio distribution of companions, as observed in different multiplicity surveys, to the most recent estimate of the single-object mass function. The main goal of our analysis is to test whether or not the observed companion mass ratio distribution (CMRD) as a function of primary star mass and star formation environment is consistent with having been drawn from the field star initial mass function (IMF). We consider samples of companions for M dwarfs, solar-type stars, and intermediate-mass stars, both in the field as well as clusters or associations, and compare them with populations of binaries generated by random pairing from the assumed IMF for a fixed primary mass. With regard to the field we can reject the hypothesis that the CMRD was drawn from the IMF for different primary mass ranges: the observed CMRDs show a larger number of equal-mass systems than predicted by the IMF. This is in agreement with fragmentation theories of binary formation. For the open clusters α Persei and the Pleiades we also reject the IMF random-pairing hypothesis. Concerning young star-forming regions, currently we can rule out a connection between the CMRD and the field IMF in Taurus but not in Chamaeleon I. Larger and different samples are needed to better constrain the result as a function of the environment. We also consider other companion mass functions and we compare them with observations. Moreover the CMRD both in the field and clusters or associations appears to be independent of separation in the range covered by the observations. Combining therefore the CMRDs of M (1-2400 AU) and G (28-1590 AU) primaries in the field and intermediate-mass primary binaries in Sco OB2 (29-1612 AU) for mass ratios, q = M [SUB]2[/SUB]/M [SUB]1[/SUB], from 0.2 to 1, we find that the best chi-square fit follows a power law dN/dqvpropq [SUP]β[/SUP], with β = -0.50 ± 0.29, consistent with previous results. Finally, we note that the Kolmogorov-Smirnov test gives a ~1% probability of the observed CMRD in the Pleiades and Taurus being consistent with that observed for solar-type primaries in the field over comparable primary mass range. This highlights the value of using CMRDs to understand which star formation events contribute most to the field.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Reggiani, Maddalena ;  Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS)
Meyer, Michael R.;  Institute of Astronomy, ETH Zurich, CH-8093 Zurich, Switzerland)
Language :
English
Title :
Binary Formation Mechanisms: Constraints from the Companion Mass Ratio Distribution
Publication date :
01 September 2011
Journal title :
Astrophysical Journal
ISSN :
0004-637X
eISSN :
1538-4357
Publisher :
IOP Publishing, Bristol, United Kingdom
Volume :
738
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
since 04 August 2017

Statistics


Number of views
28 (2 by ULiège)
Number of downloads
143 (2 by ULiège)

Scopus citations®
 
67
Scopus citations®
without self-citations
55
OpenCitations
 
88

Bibliography


Similar publications



Contact ORBi