The ASAS-SN catalogue of variable stars VI: an all-sky sample of δ Scuti stars. Issue 3 (19th February 2020)

• Record Type: Journal Article
• Authors: Jayasinghe, T; Stanek, K Z; Kochanek, C S; Vallely, P J; Shappee, B J; Holoien, T W-S; Thompson, Todd A; Prieto, J L; Pejcha, O; Fausnaugh, M; Otero, S; Hurst, N; Will, D
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 493:Issue 3(2020)
• Page Start: 4186
• Page End: 4208
• Publication Date: 2020-02-19
• Subjects: stars: binaries: eclipsing -- stars: variables: Delta Scuti -- stars: variables -- catalogues – surveys; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa499
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We characterize an all-sky catalogue of ∼8400 δ Scuti variables in ASAS-SN, which includes ∼3300 new discoveries. Using distances from Gaia DR2, we derive period–luminosity relationships for both the fundamental mode and overtone pulsators in the WJK, V, Gaia DR2 G, J, H, Ks, and W 1 bands. We find that the overtone pulsators have a dominant overtone mode, with many sources pulsating in the second overtone or higher order modes. The fundamental mode pulsators have metallicity-dependent periods, with log10 ( P ) ∼ −1.1 for $\rm [Fe/H]\lt -0.3$ and log10 ( P ) ∼ −0.9 for $\rm [Fe/H]\gt 0$, which leads to a period-dependent scale height. Stars with $P\gt 0.100\, \rm d$ are predominantly located close to the Galactic disc ($\rm |\mathit{ Z}|\lt 0.5\, kpc$ ). The median period at a scale height of $Z\sim 0\, \rm kpc$ also increases with the Galactocentric radius R, from log10 ( P ) ∼ −0.94 for sources with $R\gt 9\, \rm kpc$ to log10 ( P ) ∼ −0.85 for sources with $R\lt 7\, \rm kpc$, which is indicative of a radial metallicity gradient. To illustrate potential applications of this all-sky catalogue, we obtained 30 min cadence, image subtraction TESS light curves for a sample of 10 fundamental mode and 10 overtone δ Scuti stars discovered by ASAS-SN. From this sample, we identified two new δ Scuti eclipsing binaries, ASASSN-V J071855.62−434247.3 and ASASSN-V J170344.20−615941.2 with short orbital periods of P orb = 2.6096 and 2.5347 d, respectively.