EDP Sciences
Free Access
Volume 420, Number 2, June III 2004
Page(s) 673 - 681
Section Stellar atmospheres
DOI https://doi.org/10.1051/0004-6361:20035651

A&A 420, 673-681 (2004)
DOI: 10.1051/0004-6361:20035651

Chemical composition of the magnetic B star HR 5049

M. Nishimura1, K. Sadakane2, K. Kato3, Y. Takeda4 and G. Mathys5

1  Rakutou High School, Anshu, Yamashina-ku, Kyoto 607-8017, Japan
2  Astronomical Institute, Osaka Kyoiku University, Asahigaoka, Kashiwara, Osaka 582-8582, Japan
3  Osaka Science Museum, Nakanoshima, Kita-ku, Osaka 530-0005, Japan
4  National Astronomical Observatory, Osawa, Mitaka, Tokyo 181-8588, Japan
5  European Southern Observatory, Casilla 19001, Santiago 19, Chile

(Received 10 November 2003 / Accepted 23 February 2004)

A spectrum synthesis analysis for photospheric lines in the magnetic B star HR 5049 is presented, based on a high quality spectrogram obtained with the EMMI spectrograph attached to the NTT at ESO. It is found that light elements such as He, C and O are under-abundant. One of the most notable features is the deficiency of He by more than -2.0 dex. Co and Cl are over-abundant by +3.5 dex and +1.9 dex, respectively. Other iron peak elements are over-abundant ranging from +0.47 dex ( $\ion{Ti}{ii}$) to +1.94 dex ( $\ion{Cr}{i}$). For rare earth elements, the lines of once-ionized species are generally weak, while the third spectra (especially those of Pr and Nd) are very prominent. Although rare earth elements show significant over-abundances ranging from +3.0 dex to as large as +4.0 dex, Ba has the solar abundance. The Nd-Pr abundance difference, which shows an apparent decreasing trend with increasing effective temperature among CP stars, is found to be unusually small in HR 5049.

Key words: stars: abundances -- stars: chemically peculiar -- stars: individual: HR 5049

Offprint request: M. Nishimura, mnisimura@kcat.zaq.ne.jp

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