Ultraviolet Spectroscopic Analysis of Transient Mass Flow Outburst in U Cephei

Tupa, Peter R.; DeLeo, Gary G.; McCluskey, G. E.; Kondo, Y.; Sahade, Jorge; Giménez, Á.; Caton, D. B.

doi:10.1088/0004-637x/775/1/46

Cited by 3 publications

(1 citation statement)

References 25 publications

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“…Several Algol-type binaries with qualitatively similar evolutionary histories and similarly short periods are known (e.g. Tupa et al 2013;Rosales et al 2021), but the donors in these systems likely have higher masses and are somewhat less evolved than HD 15124. The orbit of HD 15124 is expected to widen as mass transfer continues.…”

Section: Mesa Calculationsmentioning

confidence: 99%

Birth of a Be star: an APOGEE search for Be stars forming through binary mass transfer

El-Badry¹,

Conroy²,

Quataert³

et al. 2022

Preprint

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Motivated by recent suggestions that many Be stars form through binary mass transfer, we searched the APOGEE survey for Be stars with bloated, stripped companions. From a well-defined parent sample of 297 Be stars, we identified one mass-transfer binary, HD 15124. The object consists of a main-sequence Be star (𝑀 Be = 5.3 ± 0.6 𝑀 ) with a low-mass (𝑀 donor = 0.92 ± 0.22 𝑀 ), subgiant companion on a 5.47-day orbit. The emission lines originate in an accretion disk caused by ongoing mass transfer, not from a decretion disk as in classical Be stars. Both stars have surface abundances bearing imprint of CNO processing in the donor's core: the surface helium fraction is 𝑌 He ≈ 0.6, and the nitrogen-to-carbon ratio is 1000 times the solar value. The system's properties are well-matched by binary evolution models in which mass transfer begins while a 3 − 5 𝑀 donor leaves the main sequence, with the secondary becoming the Be star. These models predict that the system will soon become a detached Be + stripped star binary like HR 6819 and LB-1, with the stripped donor eventually contracting to become a core helium-burning sdOB star. Discovery of one object in this short-lived (∼1 Myr) evolutionary phase implies the existence of many more that have already passed through it and are now Be + sdOB binaries. We infer that (28 +27 −16 ) % of Be stars have stripped companions, most of which are faint. Together with the dearth of main-sequence companions to Be stars and recent discovery of numerous Be + sdOB binaries in the UV, our results imply that binarity plays an important role in the formation of Be stars.

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Section: Mesa Calculationsmentioning

confidence: 99%

Birth of a Be star: an APOGEE search for Be stars forming through binary mass transfer

El-Badry¹,

Conroy²,

Quataert³

et al. 2022

Preprint

View full text Add to dashboard Cite

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Evolutionary inference and statistical constraints on Algols including SD2-type near contact binaries

Wang

Zhu

Yue

2022

Monthly Notices of the Royal Astronomical Society

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Algol-type binaries (Algols) have aroused extensive interests due to the idiosyncratic evolutionary stages of both components. To better understand the evolutionary properties of such characteristic population, we collected mostly double-lined samples and performed systematic work concentrated on their physical constraints. It is found that orbital period cut-off for the OB and AF type Algols are P(OB) >0.482 d, P(AF) >0.358 d; constraints on mean density and surface gravity of the secondary components are $\overline{\rho }_2$(OB) < 0.144 ρ⊙, $\overline{\rho }_2$(AF) < 0.26 ρ⊙, log g2(OB) < 4.719 cgs and log g2(AF) < 4.517 cgs. Limitations of a(OB) >3.48 R⊙ and a(AF) >2.29 R⊙ have been deduced from the a - P relation. Moreover, statistical analysis of secular period changes reveal that Algols with higher f1 and relevant shorter period generally show weak period change. It hints that there is some connections between f1 and orbital evolution. Systems with lower f1 have the chance to evolve from classic Algols to SD2-type near contact binaries; systems with higher f1 obey the evolutionary channel from SD2-type near contact binaries to contact binaries. However, it seems that SD2-type near contact binaries could not evolve toward classic Algols. As a natural lab Algols are producing peculiar stellar experimental samples via complicated astrophysical processes, which will enhance our understanding on the physical properties and evolution of such binary populations.

show abstract

Birth of a Be star: an APOGEE search for Be stars forming through binary mass transfer

El-Badry

Conroy

Quataert

et al. 2022

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

Motivated by recent suggestions that many Be stars form through binary mass transfer, we searched the APOGEE survey for Be stars with bloated, stripped companions. From a well-defined parent sample of 297 Be stars, we identified one mass-transfer binary, HD 15124. The object consists of a main-sequence Be star (MBe = 5.3 ± 0.6 M⊙) with a low-mass (Mdonor = 0.92 ± 0.22 M⊙), subgiant companion on a 5.47-day orbit. The emission lines originate in an accretion disk caused by ongoing mass transfer, not from a decretion disk as in classical Be stars. Both stars have surface abundances bearing imprint of CNO processing in the donor’s core: the surface helium fraction is YHe ≈ 0.6, and the nitrogen-to-carbon ratio is 1000 times the solar value. The system’s properties are well-matched by binary evolution models in which mass transfer begins while a 3 − 5 M⊙ donor leaves the main sequence, with the originally less massive component becoming the Be star. These models predict that the system will soon become a detached Be + stripped star binary like HR 6819 and LB-1, with the stripped donor eventually contracting to become a core helium-burning sdO/B star. Discovery of one object in this short-lived (∼1 Myr) evolutionary phase implies the existence of many more that have already passed through it and are now Be + sdO/B binaries. We infer that $(10-60)\, \%$ of Be stars have stripped companions, most of which are ∼100 × fainter than the Be stars in the optical. Together with the dearth of main-sequence companions to Be stars and recent discovery of numerous Be + sdO/B binaries in the UV, our results imply that binarity plays an important role in the formation of Be stars.

show abstract

Ultraviolet Spectroscopic Analysis of Transient Mass Flow Outburst in U Cephei

Cited by 3 publications

References 25 publications

Birth of a Be star: an APOGEE search for Be stars forming through binary mass transfer

Birth of a Be star: an APOGEE search for Be stars forming through binary mass transfer

Evolutionary inference and statistical constraints on Algols including SD2-type near contact binaries

Birth of a Be star: an APOGEE search for Be stars forming through binary mass transfer

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