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MOBSTER-V. Discover...
MOBSTER-V. Discovery of a magnetic companion star to the magnetic beta Cep pulsator HD 156424
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- Shultz, M. E. (författare)
- Univ Delaware, Dept Phys & Astron, 217 Sharp Lab, Newark, DE 19716 USA.
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- Rivinius, Th (författare)
- ESO European Org Astron Res Southern Hemisphere, Casilla 19001, Santiago 19, Chile.
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- Wade, G. A. (författare)
- Royal Mil Coll Canada, Dept Phys, Kingston, ON K7K 7B4, Canada.
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- Kochukhov, Oleg (författare)
- Uppsala universitet,Observationell astrofysik
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- Alecian, E. (författare)
- Univ Grenoble Alpes, IPAG, CNRS, F-38000 Grenoble, France.
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- David-Uraz, A. (författare)
- Univ Delaware, Dept Phys & Astron, 217 Sharp Lab, Newark, DE 19716 USA.
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- Sikora, J. (författare)
- Bishops Univ, Dept Phys & Astron, Sherbrooke, PQ J1M 1Z7, Canada.
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Univ Delaware, Dept Phys & Astron, 217 Sharp Lab, Newark, DE 19716 USA ESO European Org Astron Res Southern Hemisphere, Casilla 19001, Santiago 19, Chile. (creator_code:org_t)
- 2021-04-01
- 2021
- Engelska.
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press. - 0035-8711 .- 1365-2966. ; 504:4, s. 4850-4864
- Relaterad länk:
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http://arxiv.org/pdf...
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- HD 156424 (B2 V) is a little-studied magnetic hot star in the Sco OB4 association, previously noted to display both high-frequency radial velocity (RV) variability and magnetospheric H alpha emission. We have analysed the Transiting Exoplanet Survery Satellite (TESS) light curve, and find that it is a beta Cep pulsator with 11 detectable frequencies, 4 of which are independent p-modes. The strongest frequency is also detectable in RVs from ground-based high-resolution spectroscopy. RVs also show a long-term variation, suggestive of orbital motion with a period of similar to years; significant differences in the frequencies determined from TESS and RV data sets are consistent with a light-time effect from orbital motion. Close examination of the star's spectrum reveals the presence of a spectroscopic companion, however, as its RV is not variable it cannot be responsible for the orbital motion and we therefore infer that the system is a hierarchical triple with a so-far undetected third star. Reanalysis of least-squares deconvolution profiles from ESPaDOnS and HARPSpol spectropolarimetry reveals the surprising presence of a strong magnetic field in the companion star, with < B-z > about +1.5 kG as compared to < B-z > similar to -0.8 kG for the primary. HD 156424 is thus the second hot binary with two magnetic stars. We are unable to identify a rotational period for HD 156424A. The magnetospheric H alpha emission appears to originate around HD 156424B. Using H alpha, as well as other variable spectral lines, we determine a period of about 0.52 d, making HD 156424B one of the most rapidly rotating magnetic hot stars.
Ämnesord
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
Nyckelord
- binaries: spectroscopic
- stars: early-type
- stars: individual: HD 156424
- stars: magnetic field
- stars: oscillations
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- ref (ämneskategori)
- art (ämneskategori)
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