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Confirmation of Monoperiodicity Above 20 Seconds for Two Blue Large-Amplitude Pulsators

McWhirter, PR, Lam, MC and Steele, IA (2020) Confirmation of Monoperiodicity Above 20 Seconds for Two Blue Large-Amplitude Pulsators. Monthly Notices of the Royal Astronomical Society, 496 (2). pp. 1105-1114. ISSN 0035-8711

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Abstract

Blue Large-Amplitude Pulsators (BLAPs) are a new class of pulsating variable star. They are located close to the hot subdwarf branch in the Hertzsprung-Russell diagram and have spectral classes of late O or early B. Stellar evolution models indicate that these stars are likely radially pulsating, driven by iron group opacity in their interiors. A number of variable stars with a similar driving mechanism exist near the hot subdwarf branch with multi-periodic oscillations caused by either pressure (p) or gravity (g) modes. No multi-periodic signals were detected in the OGLE discovery light curves since it would be difficult to detect short period signals associated with higher-order p modes with the OGLE cadence. Using the RISE instrument on the Liverpool Telescope, we produced high cadence light curves of two BLAPs, OGLE-BLAP-009 ($m_{\mathrm{v}}=15.65$ mag) and OGLE-BLAP-014 ($m_{\mathrm{v}}=16.79$ mag) using a $720$ nm longpass filter. Frequency analysis of these light curves identify a primary oscillation with a period of $31.935\pm0.0098$ mins and an amplitude from a Fourier series fit of $0.236$ mag for BLAP-009. The analysis of BLAP-014 identifies a period of $33.625\pm0.0214$ mins and an amplitude of $0.225$ mag. Analysis of the residual light curves reveals no additional short period variability down to an amplitude of $15.20\pm0.26$ mmag for BLAP-009 and $58.60\pm3.44$ mmag for BLAP-014 for minimum periods of $20$ s and $60$ s respectively. These results further confirm that the BLAPs are monoperiodic.

Item Type: Article
Additional Information: This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record Paul Ross McWhirter, Marco C Lam, Iain A Steele, Confirmation of Monoperiodicity Above 20 Seconds for Two Blue Large-Amplitude Pulsators, Monthly Notices of the Royal Astronomical Society, , staa1560 is available online at:https://doi.org/10.1093/mnras/staa1560
Uncontrolled Keywords: 0201 Astronomical and Space Sciences
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press
Related URLs:
Date Deposited: 13 Jul 2020 15:00
Last Modified: 13 Jul 2020 15:00
DOI or Identification number: 10.1093/mnras/staa1560
URI: https://researchonline.ljmu.ac.uk/id/eprint/13297

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