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The All-Sky Automated Survey for Supernovae provides long baseline (∼4 yr) V - band light curves for sources brighter than V≲ 17 mag across the whole sky. We produced V - band light curves for a total of ∼61.5 million sources and systematically searched these sources for variability. We identified ∼426 000 variables, including ∼219 000 new discoveries. Most (⁠|${\sim }74{ per\ cent}$|⁠) of our discoveries are in the Southern hemisphere. Here, we use spectroscopic information from LAMOST, GALAH, RAVE, and APOGEE to study the physical and chemical properties of these variables. We find that metal-poor eclipsing binaries have orbital periods that are shorter than metal-rich systems at fixed temperature. We identified rotational variables on the main-sequence, red giant branch, and the red clump. A substantial fraction (⁠|${\gtrsim }80{ per\ cent}$|⁠) of the rotating giants have large |$v$| rot or large near-ultraviolet excesses also indicative of fast rotation. The rotational variables have unusual abundances suggestive of analysis problems. Semiregular variables tend to be lower metallicity (⁠|$\rm [Fe/H]{\sim }-0.5$|⁠) than most giant stars. We find that the APOGEE DR16 temperatures of oxygen-rich semiregular variables are strongly correlated with the W RP − W JK colour index for |$\rm T_{eff}\lesssim 3800$|  K. Using abundance measurements from APOGEE DR16, we find evidence for Mg and N enrichment in the semiregular variables. We find that the Aluminum abundances of the semiregular variables are strongly correlated with the pulsation period, where the variables with |$\rm P\gtrsim 60$|  d are significantly depleted in Al. [ABSTRACT FROM AUTHOR]

We characterize |${\sim } 71\, 200$| W Ursae Majoris (UMa) type (EW) contact binaries, including |${\sim } 12\, 600$| new discoveries, using All-Sky Automated Survey for SuperNovae (ASAN-SN) V -band all-sky light curves along with archival data from Gaia , 2MASS, AllWISE, LAMOST, GALAH, RAVE, and APOGEE. There is a clean break in the EW period–luminosity relation at |$\rm \log (\it P/{\rm d})\,{\simeq }\,{\rm -0.30}$|⁠ , separating the longer period, early-type EW binaries from the shorter period, late-type systems. The two populations are even more cleanly separated in the space of period and effective temperature, by |$T_{\rm eff}=6710\,{\rm K}-1760\,{\rm K}\, \log (P/0.5\,{\rm d})$|⁠. Early-type and late-type EW binaries follow opposite trends in T eff with orbital period. For longer periods, early-type EW binaries are cooler, while late-type systems are hotter. We derive period–luminosity relationships in the WJK , V, Gaia DR2 G, J, H, K s, and W 1 bands for the late-type and early-type EW binaries separated by both period and effective temperature, and by period alone. The dichotomy of contact binaries is almost certainly related to the Kraft break and the related changes in envelope structure, winds, and angular momentum loss. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The All-Sky Automated Survey for Supernovae (ASAS-SN) provides long baseline (∼4 yr) light curves for sources brighter than V ≲ 17 mag across the whole sky. As part of our effort to characterize the variability of all the stellar sources visible in ASAS-SN, we have produced ∼30.1 million V -band light curves for sources in the Southern hemisphere using the APASS DR9 (AAVSO Photometric All-Sky Survey Data Release) catalogue as our input source list. We have systematically searched these sources for variability using a pipeline based on random forest classifiers. We have identified |${\sim } 220\, 000$| variables, including |${\sim } 88\, 300$| new discoveries. In particular, we have discovered |${\sim }48\, 000$| red pulsating variables, |${\sim }23\, 000$| eclipsing binaries, ∼2200 δ-Scuti variables, and |${\sim }10\, 200$| rotational variables. The light curves and characteristics of the variables are all available through the ASAS-SN variable stars data base (https://asas-sn.osu.edu/variables). The pre-computed ASAS-SN V -band light curves for all the ∼30.1 million sources are available through the ASAS-SN photometry data base (https://asas-sn.osu.edu/photometry). This effort will be extended to provide ASAS-SN light curves for sources in the Northern hemisphere and for V  ≲ 17 mag sources across the whole sky that are not included in APASS DR9. [ABSTRACT FROM AUTHOR]

The variable stars in the VSX catalogue are derived from a multitude of inhomogeneous data sources and classification tools. This inhomogeneity complicates our understanding of variable star types, statistics, and properties, and it directly affects attempts to build training sets for current (and next) generation all-sky, time-domain surveys. We homogeneously analyse the All-Sky Automated Survey for SuperNovae (ASAS-SN) V -band light curves of |${\sim }412\, 000$| variables from the VSX catalogue. The variables are classified using an updated random forest classifier with an F 1 score of 99.4 per cent and refinement criteria for individual classifications. We have derived periods for |${\sim }52\, 000$| variables in the VSX catalogue that lack a period, and have reclassified |${\sim } 17\, 000$| sources into new broad variability groups with high confidence. We have also reclassified |${\sim } 94\, 000$| known variables with miscellaneous/generic classifications. The light curves, classifications, and a range of properties of the variables are all available through the ASAS-SN Variable Stars Database (https://asas-sn.osu.edu/variables). We also include the V -band light curves for a set of ∼4000 rare variables and transient sources, including cataclysmic variables, symbiotic binaries, and flare stars. [ABSTRACT FROM AUTHOR]

The All-Sky Automated Survey for Supernovae (ASAS-SN) provides long-baseline (∼4 yr) light curves for sources brighter than V ≲ 17 mag across the whole sky. The Transiting Exoplanet Survey Satellite (TESS) has started to produce high-quality light curves with a baseline of at least 27 d, eventually for most of the sky. The combination of ASAS-SN and TESS light curves probes both long- and short-term variability in great detail, especially towards the TESS continuous viewing zones (CVZ) at the ecliptic poles. We have produced ∼1.3 million V -band light curves covering a total of |${\sim }1000 \, \rm deg^2$| towards the southern TESS CVZ and have systematically searched these sources for variability. We have identified ∼11 700 variables, including ∼7 000 new discoveries. The light curves and characteristics of the variables are all available through the ASAS-SN variable stars data base (https://asas-sn.osu.edu/variables). We also introduce an online resource to obtain pre-computed ASAS-SN V -band light curves (https://asas-sn.osu.edu/photometry) starting with the light curves of the ∼1.3 million sources studied in this work. This effort will be extended to provide ASAS-SN light curves for ∼50 million sources over the entire sky. [ABSTRACT FROM AUTHOR]