THE SWIFT UVOT STARS SURVEY. II. RR LYRAE STARS in M3 and M15

Michael Hiram Siegel, Blair L. Porterfield, Benjamin G. Balzer, Lea M.Z. Hagen

Research output: Contribution to journalReview article

Abstract

We present the first results of a near-ultraviolet (NUV) survey of RR Lyrae stars from the Ultraviolet Optical Telescope (UVOT) on board the Swift Gamma-ray Burst Mission. It is well-established that RR Lyrae stars have large amplitudes in the far- and near-ultraviolet. We have used UVOT's unique wide-field NUV imaging capability to perform the first systematic NUV survey of variable stars in the Galactic globular clusters M3 and M15. We identify 280 variable stars, comprised of 275 RR Lyrae, 2 anomalous Cepheids, 1 classical Cepheid, 1 SX Phoenicis star, and 1 possible long-period or irregular variable. Only two of these are new discoveries. We compare our results to previous investigations and find excellent agreement in the periods with significantly larger amplitudes in the NUV. We map out, for the first time, an NUV Bailey diagram from globular clusters, showing the usual loci for fundamental mode RRab and first overtone RRc pulsators. We show the unique sensitivity of NUV photometry to both the temperatures and the surface gravities of RR Lyrae stars. Finally, we show evidence of an NUV period-metallicity-luminosity relationship. Future investigations will further examine the dependence of NUV pulsation parameters on metallicity and Oosterhoff classification.

Original languageEnglish (US)
Article number129
JournalAstronomical Journal
Volume150
Issue number4
DOIs
StatePublished - Oct 1 2015

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telescopes
stars
variable stars
globular clusters
metallicity
ultraviolet photometry
diagram
gravity
loci
gamma ray bursts
near fields
temperature
diagrams
luminosity
gravitation
harmonics
sensitivity
parameter

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Siegel, Michael Hiram ; Porterfield, Blair L. ; Balzer, Benjamin G. ; Hagen, Lea M.Z. / THE SWIFT UVOT STARS SURVEY. II. RR LYRAE STARS in M3 and M15. In: Astronomical Journal. 2015 ; Vol. 150, No. 4.
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abstract = "We present the first results of a near-ultraviolet (NUV) survey of RR Lyrae stars from the Ultraviolet Optical Telescope (UVOT) on board the Swift Gamma-ray Burst Mission. It is well-established that RR Lyrae stars have large amplitudes in the far- and near-ultraviolet. We have used UVOT's unique wide-field NUV imaging capability to perform the first systematic NUV survey of variable stars in the Galactic globular clusters M3 and M15. We identify 280 variable stars, comprised of 275 RR Lyrae, 2 anomalous Cepheids, 1 classical Cepheid, 1 SX Phoenicis star, and 1 possible long-period or irregular variable. Only two of these are new discoveries. We compare our results to previous investigations and find excellent agreement in the periods with significantly larger amplitudes in the NUV. We map out, for the first time, an NUV Bailey diagram from globular clusters, showing the usual loci for fundamental mode RRab and first overtone RRc pulsators. We show the unique sensitivity of NUV photometry to both the temperatures and the surface gravities of RR Lyrae stars. Finally, we show evidence of an NUV period-metallicity-luminosity relationship. Future investigations will further examine the dependence of NUV pulsation parameters on metallicity and Oosterhoff classification.",
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THE SWIFT UVOT STARS SURVEY. II. RR LYRAE STARS in M3 and M15. / Siegel, Michael Hiram; Porterfield, Blair L.; Balzer, Benjamin G.; Hagen, Lea M.Z.

In: Astronomical Journal, Vol. 150, No. 4, 129, 01.10.2015.

Research output: Contribution to journalReview article

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T1 - THE SWIFT UVOT STARS SURVEY. II. RR LYRAE STARS in M3 and M15

AU - Siegel, Michael Hiram

AU - Porterfield, Blair L.

AU - Balzer, Benjamin G.

AU - Hagen, Lea M.Z.

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AB - We present the first results of a near-ultraviolet (NUV) survey of RR Lyrae stars from the Ultraviolet Optical Telescope (UVOT) on board the Swift Gamma-ray Burst Mission. It is well-established that RR Lyrae stars have large amplitudes in the far- and near-ultraviolet. We have used UVOT's unique wide-field NUV imaging capability to perform the first systematic NUV survey of variable stars in the Galactic globular clusters M3 and M15. We identify 280 variable stars, comprised of 275 RR Lyrae, 2 anomalous Cepheids, 1 classical Cepheid, 1 SX Phoenicis star, and 1 possible long-period or irregular variable. Only two of these are new discoveries. We compare our results to previous investigations and find excellent agreement in the periods with significantly larger amplitudes in the NUV. We map out, for the first time, an NUV Bailey diagram from globular clusters, showing the usual loci for fundamental mode RRab and first overtone RRc pulsators. We show the unique sensitivity of NUV photometry to both the temperatures and the surface gravities of RR Lyrae stars. Finally, we show evidence of an NUV period-metallicity-luminosity relationship. Future investigations will further examine the dependence of NUV pulsation parameters on metallicity and Oosterhoff classification.

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