Angular momentum evolution of Algol binaries

Abstract

We have compiled the well-determined absolute parameters of Algol-type binaries. The lists contain the parameters of 74 detached and 61 semidetached close binaries. The double-lined eclipsing binaries provide not only the most accurate determinations of stellar mass, radius and temperatures but also distance-independent luminosity for each of their individual components. The distributions of the primary and secondary masses of detached binaries (DBs) are similar, whilst the secondary masses of the semidetached binaries (SDBs) are mostly smaller than 2 M with a peak in the M 2 -bin (0.21-1.0). The components of the DBs are almost all located in the main-sequence band. On the contrary, the secondary components of the SDBs have larger radii and luminosity with respect to the same mass and the same effective temperature of main-sequence counterparts. They occupy a region of the Hertzsprung-Russell diagram between terminal-age main sequence and giants. Moreover, the total angular momenta and specific angular momenta are larger for the SDBs of orbital periods with P > 5 d than those of the shorter period ones. The specific angular momenta of SDBs with periods longer than 5 d are 65 per cent greater than that of the short period group with the same mass. The DBs and the SDBs with orbital periods longer and shorter than 5 d are separated into three groups in the J/M 5/3 − q diagram. The SDBs with mass ratios greater than 0.3 and P > 5 d have almost the same angular momentum to those of DBs. However, the SDBs with short periods have the smallest angular momentum even though they have the same mass ratios. This result reveals that angular momentum loss (AML) considerably affects the evolution of close binary systems. Recently, Chen, Li & Qian suggested that, in addition to magnetic braking, a circumbinary disc may play an important role in AML from Algol-type binaries. Their calculations indicated that the evolution of Algol-type binaries can be significantly affected by the circumbinary disc. Our results show that the evolution of close binaries begins as a DB and losing angular momentum, first via stellar wind and then magnetic braking plus circumbinary disc the period is shortened and orbit shrinks. Thereafter, the evolution of the system is accelerated and mass transfer rates are enhanced which result in a smaller mass ratios.

Spin angular momentum evolution of the long-period Algols

“…Recently İbanoğlu et al (2006) compiled and analysed 61 Algols for which the fundamental parameters are well known. In Fig.…”

“…We use the observers' convention and refer to the brighter, hotter and currently more massive star as the primary component with mass M 1 and the redder, mass losing component as the secondary with mass M 2 . İbanoğlu et al (2006) arrived at several interesting observations concerning the relation between orbital angular momentum and mass.…”

Orbital period changes and the higher-order multiplicity fraction amongst SuperWASP eclipsing binaries

“…Although our collection contains proportionally far fewer contact-type binaries (or perhaps far more of the other two types), the peaks and ranges of the distributions are very similar: EWs peak around P = 0.3-0.35 d and tail off above about 1 d; EBs peak around P = 0.5 d and are very rare beyond 2 d; both types drop off sharply in period below the "short period cut-off" at around P = 0.20 d (see Lohr et al 2012Lohr et al , 2013b, for more detail on the period distribution of SuperWASP eclipsing binaries in this region). EAs have a broader peak around P = 1-3 d, and are very rare below P = 0.3 d and above P = 10 d. Catalogues of specific types of eclipsing binaries, such as classical Algols (see Budding et al 2004;Ibanoglu et al 2006 andespecially van Rensbergen et al 2011, Fig. 5), exhibit greater numbers at longer periods; however, these are less likely to be detected reliably in SuperWASP data due to time-sampling limitations or because they are brighter than V ∼ 9 mag.…”

Circumbinary disk, an efficient medium extracting orbital angular momentum in close binaries

“…However, after analyzing the data of seven CVs observed by HST (Hubble Space Telescope)/STIS (Space Telescope Imaging Spectrograph), Belle et al [33] did not obtain the exact evidence for the existence of CB disks. Based on the data analysis of 74 detached and 61 semi-detached Algol binaries, Ibanoglu et al [34] found that the angular momentum of Algol binaries with the orbital period of >5 d is larger than that of the shorter period systems even though they have the same mass ratios. Their results implied that remarkable orbital angular momentum loses during the rapid mass exchange, and therefore the CB disk may be a candidate to lose the orbital angular momentum.…”