TY - JOUR
T1 - A JVLA survey of the high-frequency radio emission of the massive magnetic B- And O-type stars
AU - Kurapati, Sushma
AU - Chandra, Poonam
AU - Wade, Gregg
AU - Cohen, David H.
AU - David-Uraz, Alexandre
AU - Gagne, Marc
AU - Grunhut, Jason
AU - Oksala, Mary E.
AU - Petit, Veronique
AU - Shultz, Matt
AU - Sundqvist, Jon
AU - Townsend, Richard H.D.
AU - ud-Doula, Asif
N1 - Funding Information:
We thank the referee for very constructive comments, which helped improve the manuscript tremendously. PC acknowledges support from the Department of Science and Technology via Swarana-Jayanti Fellowship award (file no. DST/SJF/PSA-01/2014-15). GAW acknowledges Discovery Grant support from the Natural Science and Engineering Research Council (NSERC) of Canada. AuD acknowledges support by NASA through Chandra Award numbers GO5-16005X, AR6-17002C, G06-17007B and proposal 18200020 issued by the Chandra X-ray Observatory Center which is operated by the Smithsonian Astrophysical Observatory for and behalf of NASA under contract NAS8-03060. ADU gratefully acknowledges support from the Fonds québécois de la recherche sur la nature et les technologies, and DHC for NASA Chandra grants TM4-15001B and GO6-17007D. RHDT acknowledges support from NSF SI2 grant ACI-1339600 and NASA TCAN grant NNX14AB55G. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
Publisher Copyright:
© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
PY - 2017/2/1
Y1 - 2017/2/1
N2 - We conducted a survey of seven magnetic O-type stars and eleven B-type stars with masses above 8 M☉ using the Very Large Array in the 1, 3 and 13 cm bands. The survey resulted in a detection of two O- and two B-type stars. While the detected O-type stars - HD 37742 and HD 47129 - are in binary systems, the detected B-type stars, HD 156424 and ALS 9522, are not known to be in binaries. All four stars were detected at 3 cm, whereas three were detected at 1 cm and only one star was detected at 13 cm. The detected B-type stars are significantly more radio luminous than the non-detected ones, which is not the case for O-type stars. The non-detections at 13 cm are interpreted as due to thermal free-free absorption. Mass-loss rates were estimated using 3 cm flux densities and were compared with theoretical mass-loss rates, which assume free-free emission. For HD 37742, the two values of the mass-loss rates were in good agreement, possibly suggesting that the radio emission for this star is mainly thermal. For the other three stars, the estimated mass-loss rates from radio observations were much higher than those expected from theory, suggesting either a possible contribution from non-thermal emission from the magnetic star or thermal or non-thermal emission due to interacting winds of the binary system, especially for HD 47129. All the detected stars are predicted to host centrifugal magnetospheres except HD 37742, which is likely to host a dynamical magnetosphere. This suggests that non-thermal radio emission is favoured in stars with centrifugal magnetospheres.
AB - We conducted a survey of seven magnetic O-type stars and eleven B-type stars with masses above 8 M☉ using the Very Large Array in the 1, 3 and 13 cm bands. The survey resulted in a detection of two O- and two B-type stars. While the detected O-type stars - HD 37742 and HD 47129 - are in binary systems, the detected B-type stars, HD 156424 and ALS 9522, are not known to be in binaries. All four stars were detected at 3 cm, whereas three were detected at 1 cm and only one star was detected at 13 cm. The detected B-type stars are significantly more radio luminous than the non-detected ones, which is not the case for O-type stars. The non-detections at 13 cm are interpreted as due to thermal free-free absorption. Mass-loss rates were estimated using 3 cm flux densities and were compared with theoretical mass-loss rates, which assume free-free emission. For HD 37742, the two values of the mass-loss rates were in good agreement, possibly suggesting that the radio emission for this star is mainly thermal. For the other three stars, the estimated mass-loss rates from radio observations were much higher than those expected from theory, suggesting either a possible contribution from non-thermal emission from the magnetic star or thermal or non-thermal emission due to interacting winds of the binary system, especially for HD 47129. All the detected stars are predicted to host centrifugal magnetospheres except HD 37742, which is likely to host a dynamical magnetosphere. This suggests that non-thermal radio emission is favoured in stars with centrifugal magnetospheres.
UR - http://www.scopus.com/inward/record.url?scp=85042645619&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85042645619&partnerID=8YFLogxK
U2 - 10.1093/mnras/stw2838
DO - 10.1093/mnras/stw2838
M3 - Article
AN - SCOPUS:85042645619
SN - 0035-8711
VL - 465
SP - 2160
EP - 2169
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 2
ER -