Inference for stellar opacities from seismic studies of the hybrid β Cep/SPB pulsators

Walczak, P.; Daszyńska‐Daszkiewicz, J.; Pamyatnykh, A. A.

doi:10.1051/epjconf/201715206005

Cited by 7 publications

(3 citation statements)

References 32 publications

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“…The most interesting and meaningful result of our studies is that the opacity enhancements suitable for θ Oph Aa are similar to the modifications required for the other hybrid pulsators: ν Eri (Daszyńska-Daszkiewicz et al 2017), α Lup (Walczak et al 2017a), 12 Lac (Walczak et al 2017b), γ Peg (Walczak et al 2017b) and κ Sco (Walczak et al, in preparation). The question that still remains is: what is the source of such a huge modification of the opacity data?…”

Section: Discussionsupporting

confidence: 71%

Seismic modelling of early B-type pulsators observed by BRITE: I. $θ$ Ophiuchi

Walczak,

Daszyńska-Daszkiewicz,

Pigulski

et al. 2019

Preprint

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We analyse time-series observations from the BRITE-Constellation of the well known β Cephei type star θ Ophiuchi. Seven previously known frequencies were confirmed and nineteen new frequency peaks were detected. In particular, high-order g modes, typical for the SPB (Slowly Pulsating B-type star) pulsators, are uncovered. These low-frequency modes are also obtained from the 7-year SMEI light curve. If g modes are associated with the primary component of θ Oph, then our discovery allows, as in the case of other hybrid pulsators, to infer more comprehensive information on the internal structure. To this aim we perform in-depth seismic studies involving simultaneous fitting of mode frequencies, reproducing mode instability and adjusting the relative amplitude of the bolometric flux variations. To explain the mode instability in the observed frequency range a significant increase of the mean opacity in the vicinity of the Z-bump is needed. Moreover, constraints on mass, overshooting from the convective core and rotation are derived. If the low-frequency modes come from the speckle B5 companion then taking into account the effects of rotation is enough to explain the pulsational mode instability.

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Section: Discussionsupporting

confidence: 71%

Seismic modelling of early B-type pulsators observed by BRITE: I. $θ$ Ophiuchi

Walczak,

Daszyńska-Daszkiewicz,

Pigulski

et al. 2019

Preprint

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“…The summary of the opacity modifications derived from these seismic studies is given in Table 1. More details on them can be found in Walczak et al (2017) and Daszyńska-Daszkiewicz et al (2018) or will be published soon (Walczak et al, in preparation).…”

Section: P-mode Dominated Pulsatorsmentioning

confidence: 99%

What have we learnt from pulsations of B-type stars?

Daszynska-Daszkiewicz,

Walczak,

Szewczuk

et al. 2018

Preprint

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We review the main results obtained from our seismic studies of B-type main sequence pulsators, based on the ground-based, MOST, Kepler and BRITE observations. Important constraints on stellar opacities, convective overshooting and rotation are derived. In each studied case, a significant modification of the opacity profile at the depths corresponding to the temperature range log T ∈ (5.0 − 5.5) is indispensable to explain all pulsational properties. In particular, a huge amount of opacity (at least 200%) at the depth of the temperature log T = 5.46 (the "nickel" opacity) has to be added in early B-type stellar models to account for low frequencies which correspond to high-order g modes. The values of the overshooting parameter, αov, from our seismic studies is below 0.3. In the case of a few stars, the deeper interiors have to rotate faster to get the g-mode instability in the whole observed range.

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“…Pradhan & Nahar (2009) demonstrate how a small opacity increase could resolve the solar abundance problem, which Asplund et al (2009) review. A further indication from astronomy comes from a study of β Cephei pulsation by Walczak et al (2017) who show, in the cases of ν Eri, γ Peg and 12 Lac, how an increased opacity would improve the agreement between observed and calculated pulsation frequencies.…”

Section: Astrophysical Opacitiesmentioning

confidence: 99%

Summary of Eighth Meeting on Hot Subdwarfs and Related Objects

Lynas-Gray

2017

Open Astronomy

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Subjects discussed during the Eighth Meeting on Hot Subdwarfs and Related Objects are summarised. In particular, a succinct presentation is given of challenges to stellar evolution arising from recent observations. Mention is also made of topics not covered in the meeting such as the need for small revisions to stellar envelope opacities currently in use. I conclude with a brief discussion of current developments which will influence future hot subdwarf research and necessary initiatives that need to be taken.

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Inference for stellar opacities from seismic studies of the hybrid β Cep/SPB pulsators

Cited by 7 publications

References 32 publications

Seismic modelling of early B-type pulsators observed by BRITE: I. $θ$ Ophiuchi

Seismic modelling of early B-type pulsators observed by BRITE: I. $θ$ Ophiuchi

What have we learnt from pulsations of B-type stars?

Summary of Eighth Meeting on Hot Subdwarfs and Related Objects

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