Optical–Mid-infrared Period–Luminosity Relations for W UMa-type Contact Binaries Based on Gaia DR 1: 8% Distance Accuracy

Abstract

W Ursa Majoris (W UMa)-type contact binary systems (CBs) are useful statistical distance indicators because of their large numbers. Here, we establish (orbital) period-luminosity relations (PLRs) in 12 optical-to-mid-infrared bands (GBV RIJHK s W 1W 2W 3W 4) based on 183 nearby W UMa-type CBs with accurate Tycho-Gaia parallaxes. The 1σ dispersion of the PLRs decreases from optical to near-and mid-infrared wavelengths. The minimum scatter, 0.16 mag, implies that W UMa-type CBs can be used to recover distances to 7% precision. Applying our newly determined PLRs to 19 open clusters containing W UMa-type CBs demonstrates that the PLR and open cluster CB distance scales are mutually consistent to within 1%. Adopting our PLRs as secondary distance indicators, we compiled a catalog of 55,603 CBs candidates, of which 80% have distance estimates based on a combination of optical, near-, and mid-infrared photometry. Using Fourier decomposition, 27,318 high-probability W UMa-type CBs were selected. The resulting 8% distance accuracy implies that our sample encompasses the largest number of objects with accurate distances within a local volume with a radius of 3 kpc available to date. The distribution of W UMa-type CBs in the Galaxy suggests that in different environments, the CB luminosity function may be different: larger numbers of brighter (longer-period) W UMa-type CBs are found in younger environments.

Physical Parameters of Late-type Contact Binaries in the Northern Catalina Sky Survey

“…Equipped with such a large CB sample, we can now study whether there are any systematic differences in the PLRs for different subtypes. These PLR slopes for A-and W-type CBs are consistent with the slopes derived by Chen et al (2018a), to within 2 σ. This shows that CBs obey rather tight correlations between their periods and luminosities.…”

“…This shows that CBs obey rather tight correlations between their periods and luminosities. The reason that the scatter (σ) resulting from our fits is larger than that derived by Chen et al (2018a), by 0.16 mag, is that the error propagated from the Gaia distance uncertainties is larger; Chen et al (2018a) placed tight constraints on the distance uncertainties included in their study. There are no signs of systematic zero-point differences among the various subtypes.…”

“…Since Eggen (1967) first proposed to use CBs as distance indicators, various studies have attempted to establish period-luminosity (PL)-color (PLC) relations (Rucinski 1994;Chen et al 2016b). Chen et al (2018a) managed to achieve a distance accuracy of 7% using infrared passbands 1 . This may be further improved if we can exclude the possible impact associated with using different subtypes and any dependence on the CBs' physical parameters.…”

“…In this paper, we develop an automated Wilson-Devinney-type (W-D; Wilson & Devinney 1971;Wilson 1979) code to derive physical parameters from the CB light curves, and we apply our method to a large CB sample from the CSS Data Release 1 (CSDR1 2 ; Drake et al 2014). Armed with distance information obtained from PLR analysis in infrared passbands (Chen et al 2018a), we can estimate the intrinsic properties-masses, radii, and luminosities-of 2335 CBs.…”

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

“…He found a shallower slope for the earlytype contact binaries when compared to the late-type PLR. The PLRs for late-type EW binaries have been extensively studied (Rucinski 1994;Chen et al 2016Chen et al , 2018. While the traditional period for separating early and late type EW systems is at log(P/d) = −0.25, the clear minimum in the period distribution ( Figure 4) suggests that log(P/d) = −0.30 is a better choice.…”