MOBSTER – IV. Detection of a new magnetic B-type star from follow-up spectropolarimetric observations of photometrically selected candidates★

David-Uraz, Alexandre; Shultz, Matt; Petit, Véronique; Bowman, D. M.; Erba, C.; Fine, R A; Neiner, C.; Pablo, H.; Sikora, J.; ud‐Doula, Asif; Wade, G. A.

doi:10.1093/mnras/stab899

Cited by 7 publications

(2 citation statements)

References 66 publications

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“…Zorec & Royer (2012) derived a stellar mass of 𝑀 = 3.07 ± 0.05(𝑀 ), fractional age on the main sequence 0.89 ± 0.04, and other fundamental parameters, such as 𝑇 eff = 10000 ± 257 K and log(𝐿 ★ /𝐿 ) = 2.17 ± 0.03, from Strömgren-Crawford photometry. Similar mass 𝑀 = 2.8 ± 0.1(𝑀 ) and age 394 +10 −17 Myr, which corresponds to log(Age) = 8.60 +0.02 −0.04 yr, were obtained by David-Uraz et al (2021) for HD 38170. From the analysis of Balmer line profiles we determined 𝑇 eff = 9500 ± 200 K and log 𝑔 = 3.65 ± 0.2 (see Fig.…”

Section: Hd 38170 (Tic 140288359 = Wz Col)supporting

confidence: 80%

Analysis of eight magnetic chemically peculiar stars with rotational modulation

Kobzar,

Khalack,

Bohlender

et al. 2022

Preprint

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Since the end of 2018, the Transiting Exoplanet Survey Satellite (TESS) has provided stellar photometry to the astronomical community. We have used TESS data to study rotational modulation in the light curves of a sample of chemically peculiar stars with measured large-scale magnetic fields (mCP stars). In general, mCP stars show inhomogeneous distributions of elements in their atmospheres that lead to spectroscopic (line profile) and photometric (light curve) variations commensurate with the rotational period. We analyzed the available TESS data from 50 sectors for eight targets after post-processing them in order to minimize systematic instrumental trends. Analysis of the light curves allowed us to determine rotational periods for all eight of our targets. For each star, we provide a phase diagram calculated using the derived period from the light curves and from the available measurements of the disk-averaged longitudinal magnetic field 𝐵 z . In most cases, the phased light curve and 𝐵 z measurements show consistent variability. Using our rotation periods, and global stellar parameters derived from fitting Balmer line profiles, and from Geneva and Strömgren-Crawford photometry, we determined the equatorial rotational velocities and calculated the respective critical rotational fractions 𝑣 eq /𝑣 crit . We have shown from our sample that the critical rotational fraction decreases with stellar age, at a rate consistent with the magnetic braking observed in the larger population of mCP stars.

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Section: Hd 38170 (Tic 140288359 = Wz Col)supporting

confidence: 80%

Analysis of eight magnetic chemically peculiar stars with rotational modulation

Kobzar,

Khalack,

Bohlender

et al. 2022

Preprint

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show abstract

“…Alongside spectropolarimetric observations, several properties may be used to identify magnetic candidates from photometric and spectroscopic studies, including multi-wavelength diagnostics (e.g., Babel & Montmerle 1997;Cohen et al 2003;Marcolino et al 2012;Rivinius et al 2013;Nazé et al 2014;Oksala et al 2015;Buysschaert et al 2018;Walborn et al 2015;Leto et al 2021). Most recently, TESS photometric data is being used to identify candidate magnetic stars based on characteristic light-curve variations and subsequently observe them via spectropolarimetry (David-Uraz et al 2019;Sikora et al 2019b;Shultz et al 2019c;David-Uraz et al 2021b;Shultz et al 2021a).…”

Section: Introductionmentioning

confidence: 99%

The effects of surface fossil magnetic fields on massive star evolution: IV. Grids of models at Solar, LMC, and SMC metallicities

Keszthelyi

Koter

Götberg

et al. 2022

Monthly Notices of the Royal Astronomical Society

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Magnetic fields can drastically change predictions of evolutionary models of massive stars via mass-loss quenching, magnetic braking, and efficient angular momentum transport, which we aim to quantify in this work. We use the mesa software instrument to compute an extensive main-sequence grid of stellar structure and evolution models, as well as isochrones, accounting for the effects attributed to a surface fossil magnetic field. The grid is densely populated in initial mass (3-60 M⊙), surface equatorial magnetic field strength (0-50 kG), and metallicity (representative of the Solar neighbourhood and the Magellanic Clouds). We use two magnetic braking and two chemical mixing schemes and compare the model predictions for slowly-rotating, nitrogen-enriched (‘Group 2’) stars with observations in the Large Magellanic Cloud. We quantify a range of initial field strengths that allow for producing Group 2 stars and find that typical values (up to a few kG) lead to solutions. Between the subgrids, we find notable departures in surface abundances and evolutionary paths. In our magnetic models, chemical mixing is always less efficient compared to non-magnetic models due to the rapid spin-down. We identify that quasi-chemically homogeneous main sequence evolution by efficient mixing could be prevented by fossil magnetic fields. We recommend comparing this grid of evolutionary models with spectropolarimetric and spectroscopic observations with the goals of i) revisiting the derived stellar parameters of known magnetic stars, and ii) observationally constraining the uncertain magnetic braking and chemical mixing schemes.

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Making waves in massive star asteroseismology

Bowman

2023

Astrophys Space Sci

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Massive stars play a major role not only in stellar evolution but also galactic evolution theory. This is because of their dynamical interaction with binary companions, but also because their strong winds and explosive deaths as supernovae provide chemical, radiative and kinematic feedback to their environments. Yet this feedback strongly depends on the physics of the supernova progenitor star. It is only in recent decades that asteroseismology – the study of stellar pulsations – has developed the necessary tools to a high level of sophistication to become a prime method at the forefront of astronomical research for constraining the physical processes at work within stellar interiors. For example, precise and accurate asteroseismic constraints on interior rotation, magnetic field strength and geometry, mixing and angular momentum transport processes of massive stars are becoming increasingly available across a wide range of masses. Moreover, ongoing large-scale time-series photometric surveys with space telescopes have revealed a large diversity in the variability of massive stars, including widespread coherent pulsations across a large range in mass and age, and the discovery of ubiquitous stochastic low-frequency (SLF) variability in their light curves. In this invited review, I discuss the progress made in understanding the physical processes at work within massive star interiors thanks to modern asteroseismic techniques, and conclude with a future outlook.

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MOBSTER – IV. Detection of a new magnetic B-type star from follow-up spectropolarimetric observations of photometrically selected candidates★

Cited by 7 publications

References 66 publications

Analysis of eight magnetic chemically peculiar stars with rotational modulation

Analysis of eight magnetic chemically peculiar stars with rotational modulation

The effects of surface fossil magnetic fields on massive star evolution: IV. Grids of models at Solar, LMC, and SMC metallicities

Making waves in massive star asteroseismology

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