New short-period stellar pulsators at large Galactocentric distances

Ramsay, Gavin; Napiwotzki, R.; Barclay, Thomas; Hakala, Pasi; Potter, S.; Cropper, Mark

doi:10.1111/j.1365-2966.2011.19275.x

Cited by 4 publications

(1 citation statement)

References 38 publications

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“…The resulting lightcurves had a resulting cadence of ∼1 min and, for sources brighter than g=21, the standard deviation (σ) of the light curves was <0.024 mag (Barclay et al 2011). It led to the discovery of a rare double-mode pulsating sdB star (Ramsay et al 2006, Baran et al 2011, pulsating white dwarfs and several dozen distant δ Sct or SX Phe stars (Ramsay et al 2011).…”

Section: Photometric Observationsmentioning

confidence: 99%

RATS-Kepler – a deep high-cadence survey of the Kepler field

Ramsay¹,

Brooks²,

Hakala³

et al. 2013

Monthly Notices of the Royal Astronomical Society

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We outline the purpose, strategy and first results of a deep, high cadence, photometric survey of the Kepler field using the Isaac Newton Telescope on La Palma and the MDM 1.3m Telescope on Kitt Peak. Our goal was to identify sources located in the Kepler field of view which are variable on a timescale of a few mins to 1 hour. The astrophysically most interesting sources would then have been candidates for observation using Kepler using 1 min sampling. Our survey covered ∼42% of the Kepler field of view and we have obtained light curves for 7.1×10 5 objects in the range 13< g < 20.We have discovered more than 100 variable sources which have passed our two stage identification process. As a service to the wider community, we make our data products and cleaned CCD images available to download. We obtained Kepler data of 18 sources which we found to be variable using our survey and we give an overview of the currently available data here. These sources include a pulsating DA white dwarf, eleven δ Sct stars which have dominant pulsation periods in the range 24 min to 2.35 hrs, three contact binaries, and a cataclysmic variable (V363 Lyr). One of the δ Sct stars is in a contact binary.

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Section: Photometric Observationsmentioning

confidence: 99%

RATS-Kepler – a deep high-cadence survey of the Kepler field

Ramsay¹,

Brooks²,

Hakala³

et al. 2013

Monthly Notices of the Royal Astronomical Society

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Minute-cadence observations of the LAMOST fields with the TMTS: II. Catalogues of short-period variable stars from the first 2-yr surveys

Lin

et al. 2023

Monthly Notices of the Royal Astronomical Society

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Over the past few years, wide-field time-domain surveys such as Zwicky Transient Facility and Optical Gravitational Lensing Experiment have led to discoveries of various types of interesting short-period stellar variables, such as ultracompact eclipsing binary white dwarfs (WDs), rapidly rotating magnetized WDs, transitional cataclysmic variables between hydrogen-rich and helium accretion, and blue large-amplitude pulsators (BLAPs), which greatly enrich our understandings of stellar physics under some extreme conditions. In this paper, we report the first-2-yr discoveries of short-period variables (i.e. P < 2 h) by the Tsinghua University–Ma Huateng Telescopes for Survey (TMTS). TMTS is a multitube telescope system with a field of view up to 18 deg2, which started to monitor the Large Sky Area Multi-object Fiber Spectroscopic Telescope (LAMOST) sky areas since 2020 and generated uninterrupted minute-cadence light curves for about 10 million sources within 2 yr. Adopting the Lomb–Scargle periodogram with period-dependent thresholds for the maximum powers, we identify over 1100 sources that exhibit a variation period shorter than 2 h. Compiling the light curves with the Gaia magnitudes and colours, LAMOST spectral parameters, International Variable Star Index classifications, and archived observations from other prevailing time-domain survey missions, we identified 1076 as δ Scuti stars, which allows us to study their populations and physical properties in the short-period regime. The other 31 sources include BLAPs, subdwarf B variables, pulsating WDs, ultracompact/short-period eclipsing/ellipsoidal binaries, cataclysmic variables below the period gap, etc., which are highly interesting and worthy of follow-up investigations.

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Metal-rich SX Phe stars in theKeplerfield

Nemec

Balona

Murphy

et al. 2016

Mon. Not. R. Astron. Soc.

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A spectroscopic and photometric analysis has been carried out for thirty-two candidate SX Phe variable blue straggler stars in the Kepler-field (Balona & Nemec 2012). Radial velocities (RVs), space motions (U, V, W ), projected rotation velocities (v sin i), spectral types, and atmospheric characteristics (T eff , log g, [Fe/H], ξ t , ζ RT , etc.) are presented for 30 of the 32 stars. Although several stars are metal-weak with extreme halo orbits, the mean [Fe/H] of the sample is near solar, thus the stars are more metalrich than expected for a typical sample of Pop. II stars, and more like halo metal-rich A-type stars (Perry 1969). Two thirds of the stars are fast rotators with v sin i > 50 km/s, including four stars with v sin i > 200 km/s. Three of the stars have (negative) RVs > 250 km/s, five have retrograde space motions, and 21 have total speeds (relative to the LSR) > 400 km/s. All but one of the 30 stars have positions in a Toomre diagram consistent with the kinematics of bona fide halo stars (the exception being a thick-disk star). Observed Rømer time delays, pulsation frequency modulations and light curves suggest that at least one third of the stars are in binary (or triple) systems with orbital periods ranging from 2.3 days to more than four years.

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New short-period stellar pulsators at large Galactocentric distances

Cited by 4 publications

References 38 publications

RATS-Kepler – a deep high-cadence survey of the Kepler field

RATS-Kepler – a deep high-cadence survey of the Kepler field

Minute-cadence observations of the LAMOST fields with the TMTS: II. Catalogues of short-period variable stars from the first 2-yr surveys

Metal-rich SX Phe stars in theKeplerfield

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