A PERIOD STUDY OF AW-UMA

DEMIRCAN O., DERMAN E., MUYESSEROGLU Z.

ASTRONOMY & ASTROPHYSICS, cilt.263, sa.1-2, ss.165-171, 1992 (SCI-Expanded, Scopus) identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 263 Sayı: 1-2
  • Basım Tarihi: 1992
  • Dergi Adı: ASTRONOMY & ASTROPHYSICS
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.165-171
  • Anahtar Kelimeler: STARS, BINARIES, BINARIES, ECLIPSING, STARS, EVOLUTION, AW-UMA, URSAE-MAJORIS, EVOLUTION, SYSTEMS, STARS
  • Ankara Üniversitesi Adresli: Hayır

Özet

The period variation of a highly evolved A-type contact binary AW UMa is studied. It is shown that the primary minima always occur (since approximately 1975) slightly earlier than expected (approximately 36 s). This is too large to be interpreted as the light time effect due to orbital motion of the component stars (cf. Liu et al. 1990). Such a shift could be explained in terms of a large persistent dark region on the leading hemisphere (or a bright region on the following hemisphere) close to the neck region of the primary component. A probable period jump (DELTAP is-approximately-equal-to 3 10(-6) d) around 1975 is confirmed, after Kurpinska (1980) and Hrivnak (1982). A secular period decrease with a rate between -1 10(-7) and -2 10(-7) d yr-1 is obtained mostly from our own data. The period and light curve variations are discussed within the context of angular momentum evolution of the system.