The ASAS-SN catalogue of variable stars – VII. Contact binaries are different above and below the Kraft break

Abstract

We characterize ∼71, 200 W UMa type (EW) contact binaries, including ∼12, 600 new discoveries, using ASAS-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 log(P/d) − 0.30, separating the longer period early-type (A sub-type) EW binaries from the shorter period, late-type (W sub-type) systems. The two populations are even more cleanly separated in the space of period and effective temperature, by T eff = 6710 K − 1760 K log(P/0.5 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 (PLRs) in the W J K , V, Gaia DR2 G, J, H, K s and W 1 bands for the late-type and early-type EW binaries separated both by 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.

A hundred new eclipsing binary system candidates studied in a near-infrared window in the VVV survey

“…In general, the classification of these systems in other catalogues is similar to ours. In particular, our periods exhibit good agreement with those derived by Jayasinghe et al (2020b). The mass ratio parameter of our total sample lies within the 0.30 < q < 3.74 range.…”

“…We found an average value of ∼ 0.004, within the 0.00 < e < 0.04 range. For the contact EBs, we derived a median value of the eccentricity of e ∼ 0.0027, as expected for short-period systems (see, e.g., Chen et al 2018b;Jayasinghe et al 2020b). For the detached and semi-detached EBs, we obtained eccentricities of e ∼ 0.0047 and e ∼ 0.0058, respectively.…”

“…This is due to the large photometric errors associated to the faintest stars, and thus interfere in the first detection made by Stetson index. Our studied sources were matched with different variable catalogues, such as the ASAS-SN (Jayasinghe et al 2020b), the General Catalogue of Variable Stars (GCVS) (Samus' et al 2017), the Optical Gravitational Lensing Experiment (OGLE) (Soszyński et al 2016), the WISE variable (Chen et al 2018a), and CDS X-Match Service1. a We found a total of 19 stars in our sample that had been previously detected as variable stars (Table 2).…”

Cool, Luminous, and Highly Variable Stars in the Magellanic Clouds from ASAS-SN: Implications for Thorne–Żytkow Objects and Super-asymptotic Giant Branch Stars

“…Each ASAS-SN camera has a 4.5 deg 2 field-of-view, 8″ pixels, and typical point-source FWHM of ∼2 pixels. With all-sky coverage, ASAS-SN data have already been used extensively for the analysis of Milky Way variable stars (Jayasinghe et al 2018(Jayasinghe et al , 2019a(Jayasinghe et al , 2019b(Jayasinghe et al , 2020a(Jayasinghe et al , 2020b(Jayasinghe et al , 2020cPawlak et al 2019;Percy 2019;Shields et al 2019;Auge et al 2020).…”

Zwicky Transient Facility and Globular Clusters: the Period–Luminosity and Period–Luminosity–Color Relations for Late-type Contact Binaries

“…In case of the early-type CB, the J-band PL relation was derived in Chen et al (2016), while the optical PLC relation was presented in Pawlak (2016) based on 64 early-type CB located in the Large Magellanic Cloud. Using a much larger sample of CB, Jayasinghe et al (2020) showed that early-type and late-type CB follow a different PL relation. Finally, Sun et al (2020) divided CB into three sub-classes and derived the mid-infrared W 1-band PL relation for each of them.…”