An abundance analysis of a chemically peculiar B star - JL 87

Ahmad A., Behara N. T., Jeffery C. S., ŞAHİN T., Woolf V. M.

ASTRONOMY & ASTROPHYSICS, cilt.465, sa.2, ss.541-553, 2007 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 465 Sayı: 2
  • Basım Tarihi: 2007
  • Doi Numarası: 10.1051/0004-6361:20066360
  • Dergi Adı: ASTRONOMY & ASTROPHYSICS
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.541-553
  • Anahtar Kelimeler: stars : chemically peculiar, stars : early-type, subdwarfs, stars : individual : JL 87, stars : abundances, stars : fundamental parameters, RESOLUTION OPTICAL SPECTROSCOPY, EDINBURGH-CAPE SURVEY, HELIUM-RICH, WHITE-DWARF, SDB STARS, ROTATIONAL VELOCITIES, PHYSICAL PARAMETERS, GALACTIC LATITUDES, SPECTRAL-ANALYSIS, MASS-LOSS
  • Akdeniz Üniversitesi Adresli: Hayır

Özet

Aims. The aim of this study is to understand the nature and origin of a chemically peculiar star JL 87 by measuring its physical parameters and chemical abundances.

Aims. The aim of this study is to understand the nature and origin of a chemically peculiar star JL 87 by measuring its physical parameters and chemical abundances. Methods. Physical parameters – effective temperature, surface gravity and helium abundance were measured from a moderate resolution optical spectrum using fully line-blanketed LTE model atmospheres. The effective temperature and extinction were verified by comparing FUSE, IUE spectrophotometry and optical/IR broadband photometry with theoretical flux distributions from LTE model atmospheres. The photospheric chemical abundances were measured from a high-resolution optical spectrum using LTE model atmospheres and spectral synthesis. Results. On the basis of its physical parameters and chemical abundances, we confirm that JL 87 is a chemically peculiar subluminous B star. It is significantly cooler, has a lower surface gravity and is more helium-rich than previously believed. It is moderately enriched in carbon and nitrogen, but its overall metallicity is slightly subsolar. Conclusions. The shallow-mixing model of a late core-flash on a white-dwarf cooling track currently provides the most consistent agreement with the observable properties of JL 87.