The K2 Bright Star Survey. I. Methodology and Data Release

Pope, Benjamin; White, Timothy R.; Farr, W. M.; Jiang, Yu; Greklek-McKeon, Michael; Huber, Daniel; Aerts, C.; Aigrain, S.; Bedding, Timothy R.; Boyajian, Tabetha S.; Creevey, O.

doi:10.3847/1538-4365/ab3d29

Cited by 22 publications

(12 citation statements)

References 46 publications

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“…The K2 mission allowed the rotation, pulsation, and binary properties of the seven sisters of the Pleiades to be studied in detail for the first time thanks to its long time base and high precision (White et al, 2017). Since the end of the K2 mission in 2018, these high-precision data have revealed dozens of previously unknown β Cep and SPB stars (Pope et al, 2016(Pope et al, , 2019bBurssens et al, 2019) and ubiquitous stochastic low-frequency variability in the photospheres of massive stars (Bowman et al, 2019b).…”

Section: The Kepler and K2 Missionsmentioning

confidence: 99%

Asteroseismology of High-Mass Stars: New Insights of Stellar Interiors With Space Telescopes

Bowman

2020

Front. Astron. Space Sci.

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Massive stars are important metal factories in the Universe. They have short and energetic lives, and many of them inevitably explode as a supernova and become a neutron star or black hole. In turn, the formation, evolution and explosive deaths of massive stars impact the surrounding interstellar medium and shape the evolution of their host galaxies. Yet the chemical and dynamical evolution of a massive star, including the chemical yield of the ultimate supernova and the remnant mass of the compact object, strongly depend on the interior physics of the progenitor star. We currently lack empirically calibrated prescriptions for various physical processes at work within massive stars, but this is now being remedied by asteroseismology. The study of stellar structure and evolution using stellar oscillations-asteroseismology-has undergone a revolution in the last two decades thanks to high-precision time series photometry from space telescopes. In particular, the long-term light curves provided by the MOST, CoRoT, BRITE, Kepler/K2, and TESS missions provided invaluable data sets in terms of photometric precision, duration and frequency resolution to successfully apply asteroseismology to massive stars and probe their interior physics. The observation and subsequent modeling of stellar pulsations in massive stars has revealed key missing ingredients in stellar structure and evolution models of these stars. Thus, asteroseismology has opened a new window into calibrating stellar physics within a highly degenerate part of the Hertzsprung-Russell diagram. In this review, I provide a historical overview of the progress made using ground-based and early space missions, and discuss more recent advances and breakthroughs in our understanding of massive star interiors by means of asteroseismology with modern space telescopes.

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Section: The Kepler and K2 Missionsmentioning

confidence: 99%

Asteroseismology of High-Mass Stars: New Insights of Stellar Interiors With Space Telescopes

Bowman

2020

Front. Astron. Space Sci.

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“…To increase the frequency resolution of the light curve, we extract a new, longer time-base light curve constructed via the halo photometry method (hereafter -). In this method, the scattered light from bright targets across the entire pixel image are collected, with relative weights given to each pixel to scale their contribution to the resulting light curve (White et al 2017;Pope et al 2019). Whereas -only has a time-base ∼ 29.9 d, -has a time-base of ∼ 71.3 d, improving the formal frequency resolution from = 1/ = 0.034 d −1 for -to = 1/ = 0.014 d −1 for -.…”

Section: K2 Photometrymentioning

confidence: 99%

Characterization of the variability in the O+B eclipsing binary HD 165246

Johnston

Aimar

Abdul-Masih

et al. 2021

Monthly Notices of the Royal Astronomical Society

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O-stars are known to experience a wide range of variability mechanisms originating at both their surface and their near-core regions. Characterization and understanding of this variability and its potential causes are integral for evolutionary calculations. We use a new extensive high-resolution spectroscopic data set to characterize the variability observed in both the spectroscopic and space-based photometric observations of the O+B eclipsing binary HD 165246. We present an updated atmospheric and binary solution for the primary component, involving a high level of microturbulence ($13_{-1.3}^{+1.0}\,$km s−1) and a mass of $M_1=23.7_{-1.4}^{+1.1}$ M⊙, placing it in a sparsely explored region of the Hertzsprung-Russell diagram. Furthermore, we deduce a rotational frequency of 0.690 ± 0.003 d−1 from the combined photometric and line-profile variability, implying that the primary rotates at 40% of its critical Keplerian rotation rate. We discuss the potential explanations for the overall variability observed in this massive binary, and discuss its evolutionary context.

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“…This star shows rotational variability with a period very close to 4 d. An independent analysis of TESS data by David-Uraz et al ( 2021) retrieved the same period and did not find magnetic field based on follow up spectropolarimetric observations. TIC 436723855 (HD 31373, HR 1576) shows rotational modulation with 𝑃 rot = 1.448 d as well as a weaker low-frequency sinusoidal signal at 2.644 d. No photometric variability was detected for this star by Adelman & Brunhouse (1998) and Paunzen et al (2013) whereas Pope et al (2019) classified this object as an SPB star based on K2 observations. TIC 248396674 (HD 32964, 66 Eri, Fig.…”

Section: Rotational Variabilitymentioning

confidence: 93%

TESS survey of rotational and pulsational variability of mercury-manganese stars

Kochukhov,

Khalack,

Kobzar

et al. 2021

Preprint

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Mercury-manganese (HgMn) stars are late-B upper main sequence chemically peculiar stars distinguished by large overabundances of heavy elements, slow rotation, and frequent membership in close binary systems. These stars lack strong magnetic fields typical of magnetic Bp stars but occasionally exhibit non-uniform surface distributions of chemical elements. The physical origin and the extent of this spot formation phenomenon remains unknown. Here we use 2-min cadence light curves of 64 HgMn stars observed by the TESS satellite during the first two years of its operation to investigate the incidence of rotational modulation and pulsations among HgMn stars. We found rotational variability with amplitudes of 0.1-3 mmag in 84 per cent of the targets, indicating ubiquitous presence of starspots on HgMn-star surfaces. Rotational period measurements reveal six fast-rotating stars with periods below 1.2 d, including one ultra-fast rotator (HD 14228) with a 0.34 d period. We also identify several HgMn stars showing multi-periodic g-mode pulsations, tidally induced variation and eclipses in binary systems.

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The K2 Bright Star Survey. I. Methodology and Data Release

Cited by 22 publications

References 46 publications

Asteroseismology of High-Mass Stars: New Insights of Stellar Interiors With Space Telescopes

Asteroseismology of High-Mass Stars: New Insights of Stellar Interiors With Space Telescopes

Characterization of the variability in the O+B eclipsing binary HD 165246

TESS survey of rotational and pulsational variability of mercury-manganese stars

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