Metal-rich SX Phe stars in the<i>Kepler</i>field

Nemec, J. M.; Balona, L. A.; Murphy, Simon J.; Kinemuchi, Karen; Jeon, Young‐Beom

doi:10.1093/mnras/stw3072

Cited by 25 publications

(30 citation statements)

References 237 publications

(293 reference statements)

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“…This 9.1-d binary was found by the RV method (Nemec et al 2017), but has a good PM solution using both time delays and RVs (Murphy et al 2016a). This is one of the targets classified as single in our survey (Table 1), but which now has a PM orbital solution.…”

Section: A3 Kic 6780873mentioning

confidence: 91%

Finding binaries from phase modulation of pulsating stars with Kepler: V. Orbital parameters, with eccentricity and mass-ratio distributions of 341 new binaries

Murphy

Moe

Kurtz

et al. 2017

Monthly Notices of the Royal Astronomical Society

110

129

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The orbital parameters of binaries at intermediate periods (10 2 -10 3 d) are difficult to measure with conventional methods and are very incomplete. We have undertaken a new survey, applying our pulsation timing method to Kepler light curves of 2224 main-sequence A/F stars and found 341 non-eclipsing binaries. We calculate the orbital parameters for 317 PB1 systems (single-pulsator binaries) and 24 PB2s (double-pulsators), tripling the number of intermediate-mass binaries with full orbital solutions. The method reaches down to small mass ratios q ≈ 0.02 and yields a highly homogeneous sample. We parametrize the mass-ratio distribution using both inversion and MCMC forward-modelling techniques, and find it to be skewed towards low-mass companions, peaking at q ≈ 0.2. While solar-type primaries exhibit a brown dwarf desert across short and intermediate periods, we find a small but statistically significant (2.6σ) population of extreme-mass-ratio companions (q < 0.1) to our intermediatemass primaries. Across periods of 100 -1500 d and at q > 0.1, we measure the binary fraction of current A/F primaries to be 15.4% ± 1.4%, though we find that a large fraction of the companions (21% ± 6%) are white dwarfs in post-mass-transfer systems with primaries that are now blue stragglers, some of which are the progenitors of Type Ia supernovae, barium stars, symbiotics, and related phenomena. Excluding these white dwarfs, we determine the binary fraction of original A/F primaries to be 13.9% ± 2.1% over the same parameter space. Combining our measurements with those in the literature, we find the binary fraction across these periods is a constant 5% for primaries M 1 < 0.8 M , but then increases linearly with log M 1 , demonstrating that natal discs around more massive protostars M 1 1 M become increasingly more prone to fragmentation. Finally, we find the eccentricity distribution of the main-sequence pairs to be much less eccentric than the thermal distribution.

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Section: A3 Kic 6780873mentioning

confidence: 91%

Finding binaries from phase modulation of pulsating stars with Kepler: V. Orbital parameters, with eccentricity and mass-ratio distributions of 341 new binaries

Murphy

Moe

Kurtz

et al. 2017

Monthly Notices of the Royal Astronomical Society

110

129

View full text Add to dashboard Cite

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“…SX Phe stars, on the other hand, are not a spectroscopically defined class but comprise Population II δ Sct stars, though not all of them are metal poor (Nemec et al 2017). Many SX Phe stars are identified as blue stragglers in clusters, while those in the field are often identified kinematically.…”

Section: Metal-poor Starsmentioning

confidence: 99%

“…Such objects are presumably formed by the merger of two stars or by interactions in a binary system (e.g. McNamara 2011; Nemec et al 2017). As a consequence, these stars may have enhanced helium abundance.…”

Section: Tic 224285325 = Sx Phementioning

confidence: 99%

The first view of δ Scuti and γ Doradus stars with the TESS mission

Antoci

Cunha

Bowman

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We present the first asteroseismic results for δ Scuti and γ Doradus stars observed in Sectors 1 and 2 of the TESS mission. We utilize the 2-min cadence TESS data for a sample of 117 stars to classify their behaviour regarding variability and place them in the Hertzsprung–Russell diagram using Gaia DR2 data. Included within our sample are the eponymous members of two pulsator classes, γ Doradus and SX Phoenicis. Our sample of pulsating intermediate-mass stars observed by TESS also allows us to confront theoretical models of pulsation driving in the classical instability strip for the first time and show that mixing processes in the outer envelope play an important role. We derive an empirical estimate of 74 per cent for the relative amplitude suppression factor as a result of the redder TESS passband compared to the Kepler mission using a pulsating eclipsing binary system. Furthermore, our sample contains many high-frequency pulsators, allowing us to probe the frequency variability of hot young δ Scuti stars, which were lacking in the Kepler mission data set, and identify promising targets for future asteroseismic modelling. The TESS data also allow us to refine the stellar parameters of SX Phoenicis, which is believed to be a blue straggler.

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“…SX Phe-type stars are A–F type main-sequence stars that pulsate with short periods (down to 0.03 d) and large amplitudes (up to 0.8m); see Eggen and Iben (2009); Nemec et al (2017); McNamara (2011). These properties provide almost the same, as in the W UMa-type stars case, conditions for maintaining the BCR on their planets in habitability zones.…”

Section: Post-binary Potential Biosystem Rebootmentioning

confidence: 99%

Habitable worlds of merging stars

Shevchenko

2020

International Journal of Astrobiology

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It is shown that W UMa-type and SX Phe-type stellar populations are both perfectly and uniquely suited for maintaining hyper-effective biopolymer chain reactions (BCR) on their planets once the planet is in the stellar habitable zone. W UMa-type stars are known to be contact binaries, and SX Phe-type stars are presumably post-binaries, i.e., products of stellar mergers. In case of the contact binaries, the eclipse-driven periodic heating/cooling of planetary surfaces has period-amplitude parameters that perfectly satisfy stringent conditions for maintaining BCR-like reactions. In case of the post-binaries, the stars pulsate with periods and amplitudes also perfectly suited for maintaining the reactions. Therefore, the ‘W UMa – SX Phe’ metamorphosis (from a contact binary to a post-binary, via the merger) seems to provide a potential biosystem reboot on planets in these systems.

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Metal-rich SX Phe stars in theKeplerfield

Cited by 25 publications

References 237 publications

Finding binaries from phase modulation of pulsating stars with Kepler: V. Orbital parameters, with eccentricity and mass-ratio distributions of 341 new binaries

Finding binaries from phase modulation of pulsating stars with Kepler: V. Orbital parameters, with eccentricity and mass-ratio distributions of 341 new binaries

The first view of δ Scuti and γ Doradus stars with the TESS mission

Habitable worlds of merging stars

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