TY - JOUR
T1 - The VAST survey - III. the multiplicity of A-type stars within 75 pc
AU - De Rosa, R. J.
AU - Patience, Jennifer
AU - Wilson, P. A.
AU - Schneider, A.
AU - Wiktorowicz, S. J.
AU - Vigan, A.
AU - Marois, C.
AU - Song, I.
AU - Macintosh, B.
AU - Graham, J. R.
AU - Doyon, R.
AU - Bessell, M. S.
AU - Thomas, S.
AU - Lai, O.
PY - 2013/11
Y1 - 2013/11
N2 - With a combination of adaptive optics imaging and a multi-epoch common proper motion search, we have conducted a large volume-limited (D ≤ 75 pc) multiplicity survey of Atype stars, sensitive to companions beyond 30 au. The sample for the Volume-limited A-STar (VAST) survey consists of 435 A-type stars: 363 stars were observed with adaptive optics, 228 stars were searched for wide common proper motion companions and 156 stars were measured with both techniques. The projected separation coverage of the VAST survey extends from 30 to 45 000 au.Atotal of 137 stellar companions were resolved, including 64 newdetections from the VAST survey, and the companion star fraction, projected separation distribution and mass ratio distribution were measured. The separation distribution forms a log-normal distribution similar to the solar-type binary distribution, but with a peak shifted to a significantly wider value of 387+132-98 au. Integrating the fit to the distribution over the 30 to 10 000 au observed range, the companion star fraction for A-type stars is estimated as 33.8 ± 2.6 per cent. The mass ratio distribution of closer (<125 au) binaries is distinct from that of wider systems, with a flat distribution for close systems and a distribution that tends towards smaller mass ratios for wider binaries. Combining this result with previous spectroscopic surveys of A-type stars gives an estimate of the total companion star fraction of 68.9 ± 7.0 per cent. The most complete assessment of higher order multiples was estimated from the 156 star subset of the VAST sample with both adaptive optics and common proper motion measurements, combined with a thorough literature search for companions, yielding a lower limit on the frequency of single, binary, triple, quadruple and quintuple A-type star systems of 56.4+3.8-4.0, 32.1+3.9-3.5, 9.0+2.8-1.8, 1.9+1.8-0.6 and 0.6+1.4-0.2 per cent, respectively.
AB - With a combination of adaptive optics imaging and a multi-epoch common proper motion search, we have conducted a large volume-limited (D ≤ 75 pc) multiplicity survey of Atype stars, sensitive to companions beyond 30 au. The sample for the Volume-limited A-STar (VAST) survey consists of 435 A-type stars: 363 stars were observed with adaptive optics, 228 stars were searched for wide common proper motion companions and 156 stars were measured with both techniques. The projected separation coverage of the VAST survey extends from 30 to 45 000 au.Atotal of 137 stellar companions were resolved, including 64 newdetections from the VAST survey, and the companion star fraction, projected separation distribution and mass ratio distribution were measured. The separation distribution forms a log-normal distribution similar to the solar-type binary distribution, but with a peak shifted to a significantly wider value of 387+132-98 au. Integrating the fit to the distribution over the 30 to 10 000 au observed range, the companion star fraction for A-type stars is estimated as 33.8 ± 2.6 per cent. The mass ratio distribution of closer (<125 au) binaries is distinct from that of wider systems, with a flat distribution for close systems and a distribution that tends towards smaller mass ratios for wider binaries. Combining this result with previous spectroscopic surveys of A-type stars gives an estimate of the total companion star fraction of 68.9 ± 7.0 per cent. The most complete assessment of higher order multiples was estimated from the 156 star subset of the VAST sample with both adaptive optics and common proper motion measurements, combined with a thorough literature search for companions, yielding a lower limit on the frequency of single, binary, triple, quadruple and quintuple A-type star systems of 56.4+3.8-4.0, 32.1+3.9-3.5, 9.0+2.8-1.8, 1.9+1.8-0.6 and 0.6+1.4-0.2 per cent, respectively.
KW - Binaries:Close
KW - Binaries:General
KW - Binaries:Visual
KW - Stars:Early-type
KW - Techniques:High angular resolution
UR - http://www.scopus.com/inward/record.url?scp=84890918058&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84890918058&partnerID=8YFLogxK
U2 - 10.1093/mnras/stt1932
DO - 10.1093/mnras/stt1932
M3 - Article
AN - SCOPUS:84890918058
SN - 0035-8711
VL - 437
SP - 1216
EP - 1240
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 2
ER -