THE HOT COMPANION AND CIRCUMBINARY DISK OF THE Be STAR HR 2142

Peters, Geraldine J.; Wang, Luqian; Gies, Douglas R.; Grundstrom, Erika D.

doi:10.3847/0004-637x/828/1/47

Cited by 55 publications

(77 citation statements)

References 38 publications

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“…This star becomes the dominant light source and a Be star with a small, 1.5M ⊙ companion with a long orbital period of 126 d. This situation appears to be common for a wide variety of Be stars. Similar direct ultraviolet detections of hot subdwarf companions have been accomplished for FY CMa (Peters et al 2008), 59 Cyg (Peters et al 2013), HR 2142 (Peters et al 2016), and o Pup (Rivinius et al 2012, Koubský et al 2012) all with small mass functions in the range of 2 × 10 −3 − 1.3 × 10 −2 M ⊙ . Other Be binaries that have not had direct detections of the companion stars such as γ Cas (Smith et al 2012) or ζ Tau (Ruždjak et al 2009) also show similar mass functions (f (M ) = 1 × 10 −3 and f (M ) = 6 × 10 −3 respectively) that indicate low-mass companions.…”

Section: Discussionsupporting

confidence: 61%

A Spectroscopic Orbit for the Late-type Be Star β CMi

Richardson

Gerhartz

Bjorkman

et al. 2017

ApJ

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The late-type Be star β CMi is remarkably stable compared to other Be stars that have been studied. This has led to a realistic model of the outflowing Be disk by Klement et al. These results showed that the disk is likely truncated at a finite radius from the star, which Klement et al. suggest is evidence for an unseen binary companion in orbit. Here we report on an analysis of the Ritter Observatory spectroscopic archive of β CMi to search for evidence of the elusive companion. We detect periodic Doppler shifts in the wings of the Hα line with a period of 170 d and an amplitude of 2.25 km s −1 , consistent with a low-mass binary companion (M ≈ 0.42M ⊙ ). We then compared the small changes in the violet-to-red peak height changes (V /R) with the orbital motion. We find weak evidence that it does follow the orbital motion, as suggested by recent Be binary models by Panoglou et al. Our results, which are similar to those for several other Be stars, suggest that β CMi may be a product of binary evolution where Roche lobe overflow has spun up the current Be star, likely leaving a hot subdwarf or white dwarf in orbit around the star. Unfortunately, no direct sign of this companion star is found in the very limited archive of International Ultraviolet Explorer spectra.

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Section: Discussionsupporting

confidence: 61%

A Spectroscopic Orbit for the Late-type Be Star β CMi

Richardson

Gerhartz

Bjorkman

et al. 2017

ApJ

Self Cite

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“…All binary parameters are therefore similar to the αss = 0.1 simulation (#42), except for the orbital period. The dynamical spectrum of this system at inclination angle i = 60 • (Figure 15) matches well its observational equivalent (Peters et al 2016, bottom panel of their figure 4). Peters et al (2016) estimate the inclination angle within the range 65 − 85 • .…”

Section: Flat-topped Line Profilessupporting

confidence: 76%

“…The dynamical spectrum of this system at inclination angle i = 60 • (Figure 15) matches well its observational equivalent (Peters et al 2016, bottom panel of their figure 4). Peters et al (2016) estimate the inclination angle within the range 65 − 85 • . The profiles of Hanuschik et al (1996) for HR 2142 are similar in shape to the profiles of Figure 7 (at i = 60 • ), but not in intensity (emission height).…”

Section: Flat-topped Line Profilessupporting

confidence: 76%

“…the H α profiles given for HR 2142 in figure 23 of Hanuschik et al (1996). HR 2142 is a binary system (Peters 1983) consisting of a Be star and a subdwarf O star, with period P orb ≃ 81 d, mass ratio qr ≃ 0.07, and presumably zero eccentricity (Peters et al 2016). All binary parameters are therefore similar to the αss = 0.1 simulation (#42), except for the orbital period.…”

Section: Flat-topped Line Profilesmentioning

confidence: 70%

“…Furthermore, the line emission changes with the inclination angle (Figure 5i), hence an inclination slightly different to 60 • might increase the H α line emission but roughly preserving the overall shape. This could enhance the assumption of higher inclination by Peters et al (2016).…”

Section: Flat-topped Line Profilesmentioning

confidence: 99%

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Be discs in coplanar circular binaries: Phase-locked variations of emission lines

Panoglou

Faes

Carciofi

et al. 2017

Monthly Notices of the Royal Astronomical Society

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The first results of radiative transfer calculations on decretion discs of binary Be stars are presented. A smoothed particle hydrodynamics code computes the structure of Be discs in coplanar circular binary systems for a range of orbital and disc parameters. The resulting disc configuration consists of two spiral arms, and can be given as input into a Monte Carlo code, which calculates the radiative transfer along the line of sight for various observational coordinates. Making use of the property of steady disc structure in coplanar circular binaries, observables are computed as functions of the orbital phase. Orbital-phase series of line profiles are given for selected parameter sets under various viewing angles, to allow comparison with observations. Flat-topped profiles with and without superimposed multiple structures are reproduced, showing, for example, that triple-peaked profiles do not have to be necessarily associated with warped discs and misaligned binaries. It is demonstrated that binary tidal effects give rise to phase-locked variability of the violet-to-red (V/R) ratio of hydrogen emission lines. The V/R ratio exhibits two maxima per cycle; in certain cases those maxima are equal, leading to a clear new V/R cycle every half orbital period. This study opens a way in identifying binaries and in constraining the parameters of binary systems that exhibit phase-locked variations induced by tidal interaction with a companion star.

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Scientific Context

Bodensteiner

2022

Observational Imprints of Binary Evolution on B- And Be-Star Populations

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THE HOT COMPANION AND CIRCUMBINARY DISK OF THE Be STAR HR 2142

Cited by 55 publications

References 38 publications

A Spectroscopic Orbit for the Late-type Be Star β CMi

A Spectroscopic Orbit for the Late-type Be Star β CMi

Be discs in coplanar circular binaries: Phase-locked variations of emission lines

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