Modeling of accretion disk-originated features in the high resolution spectra of U Sge

Taspinar O., Bakis H., Bakis V.

CONTRIBUTIONS OF THE ASTRONOMICAL OBSERVATORY SKALNATE PLESO, vol.49, no.2, pp.427-429, 2019 (SCI-Expanded) identifier

  • Publication Type: Article / Article
  • Volume: 49 Issue: 2
  • Publication Date: 2019
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.427-429
  • Keywords: binary stars, mass transfer, accretion disk
  • Akdeniz University Affiliated: Yes


U Sge (HD 181182) belongs to the group of short period Algol-type binaries with a period of 3.38 days. One hundred and eleven high-resolution spectra of U Sge, which are known to exhibit H-alpha emission, were obtained at (TUBITAK) National Observatory in Turkey. The emission and absorption structures of the system have been analysed. The astrophysical parameters of the system have been obtained by means of analysing the spectral and photometric data. Accordingly, the primary component is a B7-8 spectral type main-sequence star, while the secondary component is a G2 spectral type giant. The cool secondary component has filled its Roche lobe and is transferring material through the L 1 point onto the hot primary component. The effects of both components and the transferring material were detected in the H-alpha lines. In order to determine these effects, the SHELLSPEC code, which uses an LTE approximation, has been used. The circumstellar structure around U Sge is due to a very low density disk, transferring material, a hot spot where the transferring material from the secondary impacts onto the primary and the magnetic activity from secondary itself. Moreover, all of these effects on the system are highly variable in just a few orbital cycles.