Optical Photometry and Spectroscopy of the Suspected "Cool Algol" AV Delphini: Determination of the Physical Properties

Abstract

We present new spectroscopic and BVRI photometric observations of the double-lined eclipsing binary AV Del ( period ¼ 3:85 days) conducted over six observing seasons. A detailed radial velocity and light-curve analysis of the optical data shows the system to be most likely semidetached, with the less massive and cooler star filling its Roche lobe. The system is probably a member of the rare class of ''cool Algol'' systems, which are distinguished from the ''classical'' Algol systems in that the mass-gaining component is also a late-type star rather than a B-or A-type star. By combining the spectroscopic and photometric analyses, we derive accurate absolute masses for the components of M 1 ¼ 1:453 AE 0:028 M and M 2 ¼ 0:705 AE 0:014 M and radii of R 1 ¼ 2:632 AE 0:030 R and R 2 ¼ 4:233 AE 0:060 R , as well as effective temperatures of 6000 AE 200 and 4275 AE 150 K for the primary and secondary, respectively. There are no obvious signs of activity (spottedness) in the optical light curve of the binary.

An Accretion-Disc Model for the Algol-Type Eclipsing Binary System AV Del

“…Initially, solutions were obtained assuming l 3 6 ¼ 0.0, but this assumption never resulted in satisfactory fits to the observations. Mader et al (2005) calculated a linear ephemeris:…”

“…On the other hand, the R filter observations of Mader et al (2005) were considered for the solutions since, as shown in Table 2, the accuracy of the results for this filter is greater than for the others.…”

“…First, it presents the analysis of the system using the latest version (Van Hamme & Wilson 2007) of the WD code in section 3 and shows a new analysis of light and radial-velocity curves, then determines the physical and absolute parameters of the system. The study is replicated without following that of Mader et al (2005) because it uses the latest version of the WD code and should obtain more parameters of the system with more accuracy than those found by Mader et al (2005).…”

The Effect of Circumstellar Material on the Light Curves of Eclipsing Binary Systems

“…Now that we understand the influence of various parameters on the emerging light curve, we can proceed to fit the real light curve of AV Del. We used the photometric data reported by Mader et al (2005) for analysis via the SHELLSPEC code. A detailed study of these data is published in Ghoreyshi et al (2011), in which an analysis of the photometric and radial-velocity data of the system by using both Wilson-Devinney code (Wilson & Devinney 1971;Wilson 1979Wilson , 1990) and the SHELLSPEC code performed.…”

Astrophysics in 2005

“…And please wave goodbye to the following sorts of binary system, since we will not mention them again, at least until Ap06-Cool Algols (Mader 2005 on AV Del, the 7th with an orbit, the first having come from Popper 1976). Also Algols with superhumps, which, like CV superhumps, are caused by a beat frequency between the orbit and disk precession frequencies (Retter et al 2005).…”