2MASS J15274848+3536572 (J1527) is a semidetached binary system consisting of a main-sequence star and a white dwarf (WD) in an orbit of 0.2556686 day. The magnetic braking (MB) mechanism plays an important role in driving the mass transfer of binary systems with an orbital period longer than 3 hr. Based on the standard and saturated MB laws, in this work we perform a detailed stellar evolution model for the formation of J1527. The simulated results indicate that two MB laws can successfully reproduce the observed orbital period, WD mass, donor-star mass, donor-star radius, surface gravity (logg) and effective temperature of the donor star. However, the standard and saturated MB laws predicted a current mass transfer rate of 10−8 and 7.5 × 10−10 M⊙ yr−1, respectively, which are much higher than the inferred value (≤3.9 × 10−11 M⊙ yr−1) according to the effective temperature detected in the WD. A sudden mass loss (4 × 10−4 M⊙) caused by the recent strong hydrogen shell flash on the surface of the WD could result in an instantaneous orbital expansion and a sharp decay of the mass-transfer rate. To produce inferred mean mass transfer rate, it requires a relatively low mass transfer rate prior to the hydrogen shell flash, which favors the saturated MB law.

There are currently no refbacks.