The giant planet orbiting the cataclysmic binary DP Leonis

Abstract

Planets orbiting post-common envelope binaries provide fundamental information on planet formation and evolution, especially for the yet nearly unexplored class of circumbinary planets. We searched for such planets in DP Leo, an eclipsing short-period binary, which shows long-term eclipse-time variations. Using published, reanalysed, and new mid-eclipse times of the white dwarf in DP Leo, obtained between 1979 and 2010, we find agreement with the light-travel-time effect produced by a third body in an elliptical orbit. In particular, the measured binary period in 2009/2010 and the implied radial velocity coincide with the values predicted for the motion of the binary and the third body around the common center of mass. The orbital period, semi-major axis, and eccentricity of the third body are P c = 28.0 ± 2.0 yrs, a c = 8.2 ± 0.4 AU, and e c = 0.39 ± 0.13. Its mass of sin i c M c = 6.1 ± 0.5 M Jup qualifies it as a giant planet. It formed either as a first generation object in a protoplanetary disk around the original binary or as a second generation object in a disk formed in the common envelope shed by the progenitor of the white dwarf. Even a third generation origin in matter lost from the present accreting binary can not be entirely excluded. We searched for, but found no evidence for a fourth body.

Planet formation from the ejecta of common envelopes

“…For the CVs, we find very good agreement in all three cases, with mass differences of less than a factor of 2. For the system DP Leo, we note that Schwope et al (2002) provide different stellar masses than Pandel et al (2002) and Beuermann et al (2011), but the resulting planetary masses are both comparable to the value derived by Zorotovic & Schreiber (2013).…”

“…For the system DP Leo, the index (1) refers to stellar masses as given by Pandel et al (2002) and Beuermann et al (2011), while (2) is based on the masses given by Schwope et al (2002). Beuermann et al (2011), as well as by Schwope et al (2002). We find that the theoretical predictions mark a narrow curve in the parameter space, and even 7 of our sources (8 data points due to DP Leo) are close to this curve.…”

“…We therefore give the value r P for our fiducial scenario (α L = 12.5) and a more conservative case r P,cons (α L = 4). For the system DP Leo, the index (1) refers to stellar masses as given by Pandel et al (2002) and Beuermann et al (2011), while (2) is based on the masses given by Schwope et al (2002). Beuermann et al (2011), as well as by Schwope et al (2002).…”

The Dwarf project: Eclipsing binaries – precise clocks to discover exoplanets

“…Timing of the eclipses in binary stars served as a tool to detect unseen components for several decades (see Pribulla & Rucinski, 2006;Beuermann et al 2011). Unlike the RV variations, the amplitude of the observed LITE increases with orbital period (see equation 5).…”

Long-Term Monitoring of Polars

“…DP Leo is an interesting and important polar since it is a member of the post-common envelope binaries group with known/suspected planet companions (Beuermann et al 2011). Recently, Beuermann et al (2011) found the physical parameters of the third body using mid-eclipse times of the WD obtained during the last 21 years. Since the system is faint and requires a long exposure time, we could not deduce an accurate long term light variation (see Kalomeni 2011).…”