CaltechAUTHORS
Published June 2022 | Version Published + Accepted Version
Journal Article Open

The OmegaWhite survey for short-period variable stars – VII. High amplitude short-period blue variables

Creators

  • 1. ROR icon Armagh Observatory
  • 2. ROR icon University of Cape Town
  • 3. ROR icon Texas Tech University
  • 4. ROR icon California Institute of Technology
  • 5. ROR icon Northwestern University
  • 6. ROR icon South African Radio Astronomy Observatory
  • 7. ROR icon Radboud University Nijmegen
  • 8. ROR icon University of Erlangen-Nuremberg
  • 9. ROR icon European Southern Observatory

Abstract

Blue Large-Amplitude Pulsators (BLAPs) are a relatively new class of blue variable stars showing periodic variations in their light curves with periods shorter than a few tens of minutes and amplitudes of more than 10 per cent. We report nine blue variable stars identified in the OmegaWhite survey conducted using ESO's VST, which shows a periodic modulation in the range 7–37 min and an amplitude in the range 0.11–0.28 mag. We have obtained a series of followup photometric and spectroscopic observations made primarily using SALT and telescopes at SAAO. We find four stars which we identify as BLAPs, one of which was previously known. One star, OW  J0820–3301, appears to be a member of the V361 Hya class of pulsating stars and is spatially close to an extended nebula. One further star, OW J1819–2729, has characteristics similar to the sdAV pulsators. In contrast, OW J0815–3421 is a binary star containing an sdB and a white dwarf with an orbital period of 73.7 min, making it only one of six white dwarf-sdB binaries with an orbital period shorter than 80 min. Finally, high cadence photometry of four of the candidate BLAPs show features that we compare with notch-like features seen in the much longer period Cepheid pulsators.

Additional Information

© 2022 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model). Accepted 2022 April 6. Received 2022 April 6; in original form 2022 February 16. Published: 12 April 2022. The targets identified in this paper were identified in data obtained using the ESO VST and OmegaCam under proposals: 088.D-4010; 090.D-0703; 091.D-0716; 092.D-0853; 093.D-0753; 093.D-0937; 094.D-0502; 095.D-0315; 096.D-0169; 097.D-0105; 098.D-0130; 099.D-0164; and 0100.D-0066. SALT spectroscopic data were obtained under proposals: 2015-2-SCI-035; 2016-1-DDT-004; 2016-1-MLT-010; 2016-1-SCI-015; and 2017-2-SCI-051. This paper uses observations made at the South African Astronomical Observatory and the South African Large Telescope, and we thank the staff for their expertise in obtaining these data. Based on observations made with the WHT (programme ID: W/16B/N4) operated on the island of La Palma by the Isaac Newton Group of Telescopes in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. PAW acknowledges support from UCT and the NRF. TK acknowledges support from the National Science Foundation through grant AST #2107982, from NASA through grant 80NSSC22K0338, and from STScI through grant HST-GO-16659.002-A. PJG acknowledges support from NOVA for the original OmegaWhite observations in the Dutch VST/Omegacam GTO observations. PJG is supported by NRF SARChI Grant 111693. Armagh Observatory and Planetarium is core funded by the Northern Ireland Executive through the Department for Communities. UH and AI acknowledge funding by the Deutsche Forschungsgemeinschaft (DFG) through grants HE1356/70-1 and HE1356/71-1. We thank Kinwah Wu for a useful discussion on probabilities of stars being spatially nearby and Evan Bauer who generated the evolutionary tracks shown in Fig. 14. We thank Steven Hämmerich for providing us with synthetic spectra for solar metal composition. We thank the referee for a useful report. Data Availability: The images obtained as part of the OW survey can be accessed through the ESO portal. Light curves and spectra can be obtained via a reasonable request from the authors.

Attached Files

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Accepted Version - 2204.03265.pdf

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Additional details

Identifiers

Eprint ID
115683
Resolver ID
CaltechAUTHORS:20220719-97729700

Related works

Describes
https://arxiv.org/abs/2204.03265 (URL)

Funding

University of Cape Town
NSF
AST-2107982
NASA
80NSSC22K0338
NASA Hubble Fellowship
HST-GO-16659.002-A
Nederlandse Onderzoekschool voor de Astronomie (NOVA)
National Research Foundation (South Africa)
111693
Department for Communities (Ireland)
Deutsche Forschungsgemeinschaft (DFG)
HE1356/70-1
Deutsche Forschungsgemeinschaft (DFG)
HE1356/71-1

Dates

Created
2022-07-20
Created from EPrint's datestamp field
Updated
2022-07-20
Created from EPrint's last_modified field