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We report the discovery of an eclipsing binary -- PTF1 J072456$+$125301-- composed of a subdwarf B (sdB) star ($g=17.2^m$) with a faint companion. Subdwarf B stars are core helium-burning stars, which can be found on the extreme horizontal branch. About half of them reside in close binary systems, but few are known to be eclipsing, for which fundamental stellar parameters can be derived. ewline We conducted an analysis of photometric data and spectra from the Palomar 60 and the 200 Hale telescope respectively. A quantitative spectral analysis found an effective temperature of $T_{text{eff}}=33900pm350$,K, log g = $5.74pm0.08$ and log($n_{text{He}}/n_{text{H}}) = -2.02 pm0.07$, typical for an sdB star. The companion does not contribute to the optical light of the system, except through a distinct reflection effect. From the light curve an orbital period of 0.09980(25),d and a system inclination of $83.56pm0.30,^{circ}$ were derived. The radial velocity curve yielded an orbital semi-amplitude of $K_1=95.8pm 8.1,text{km s$^{-1}$}$. The mass for the M-type dwarf companion is $0.155pm0.020,M_{odot}$. PTF1,J072456$+$125301 has similar atmospheric parameters to those of pulsating sdB stars (V346 Hya stars). Therefore it could be a high-priority object for asteroseismology, if pulsations were detected such as in the enigmatic case of NY Vir.
EPIC 216747137 is a new HW~Virginis system discovered by the Kepler spacecraft during its K2 second life. Like the other HW Vir systems, EPIC 216747137 is a post-common-envelope eclipsing binary consisting of a hot subluminous star and a cool low-mas
A growing number of eclipsing binary systems of the HW Vir kind (i. e., composed by a subdwarf-B/O primary star and an M dwarf secondary) show variations in their orbital period, also called Eclipse Time Variations (ETVs). Their physical origin is no
We present the discovery of the hot subdwarf B star (sdB) binary PTF1 J082340.04+081936.5. The system has an orbital period P$_{rm orb}=87.49668(1)$ min (0.060761584(10) days), making it the second-most compact sdB binary known. The lightcurve shows
The formation of subdwarf B (sdB) stars is not well understood within the current framework of stellar single and binary evolution. In this study, we focus on the formation and evolution of the pulsating sdB star in the very short-period eclipsing bi
Hot subdwarf B stars (sdBs) are extreme horizontal branch stars believed to originate from close binary evolution. Indeed about half of the known sdB stars are found in close binaries with periods ranging from a few hours to a few days. The enormous