Article (Scientific journals)
Velocity monitoring of γ Cas stars reveals their binarity status
Nazé, Yaël; Rauw, Grégor; Czesla, Stefan et al.
2022In Monthly Notices of the Royal Astronomical Society, 510, p. 2286-2304
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Keywords :
binaries: general; stars: early-type; stars: emission-line; Be; stars: massive; stars: variables: general; Astrophysics - Solar and Stellar Astrophysics
Abstract :
[en] The binary status of γ Cas stars has been discussed while theoretically examining the origin of their peculiar X-ray emission. However, except in two cases, no systematic radial velocity monitoring of these stars had been undertaken yet to clarify their status. We now fill this gap using TIGRE, CARMENES, and UVES high-resolution spectroscopy. Velocities were determined for 16 stars, revealing shifts and/or changes in line profiles. The orbit of six new binaries could be determined: the long periods (80-120 d) and small velocity amplitudes (5-7 km s[SUP]-1[/SUP]) suggest low mass companions (0.6-1 M[SUB]⊙[/SUB]). The properties of the known γ Cas binaries appear similar to those of other Be systems, with no clear-cut separation between them. One of the new systems is a candidate for a rare case of quadruple system involving a Be star. Five additional γ Cas stars display velocity variations compatible with the presence of companions, but no orbital solution could yet be formally established for them hence they only receive the status of 'binary candidate'.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Nazé, Yaël  ;  Université de Liège - ULiège > Groupe d'astrophysique des hautes énergies (GAPHE)
Rauw, Grégor  ;  Université de Liège - ULiège > Groupe d'astrophysique des hautes énergies (GAPHE)
Czesla, Stefan;  Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, D-21029 Hamburg, Germany
Smith, Myron A.;  NSF OIR Lab, 950 N Cherry Ave, Tucson, AZ 85721, USA
Robrade, Jan;  Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, D-21029 Hamburg, Germany)
Language :
English
Title :
Velocity monitoring of γ Cas stars reveals their binarity status
Publication date :
01 February 2022
Journal title :
Monthly Notices of the Royal Astronomical Society
ISSN :
0035-8711
eISSN :
1365-2966
Publisher :
Oxford University Press, Oxford, United Kingdom
Volume :
510
Pages :
2286-2304
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
since 17 January 2022

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