Volume 412, Number 3, December IV 2003
|Page(s)||829 - 836|
|Section||Stellar structure and evolution|
|Published online||08 December 2003|
The chemical composition of the peculiar companion to the millisecond pulsar in NGC 6397*
Dipartimento di Astronomia Università di Bologna, via Ranzani 1, 40127 Bologna, Italy
2 INAF–Osservatorio Astronomico di Padova, vicolo dell'Osservatorio 5, 35122 Padova, Italy
3 INAF–Osservatorio Astronomico di Bologna, via Ranzani 1, 40126 Bologna, Italy
4 INAF–Osservatorio Astronomico di Cagliari, Loc. Poggio dei Pini, Strada 54, 09012 Capoterra, Italy
5 Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, NY 10027, USA
6 Dipartimento di Fisica Università di Cagliari, Cittadella Universitaria, 09042 Monserrato, Italy
Corresponding author: E. Sabbi, email@example.com
Accepted: 19 September 2003
We present the chemical composition of the bright companion to the millisecond pulsar J1740-5340 in NGC 6397, based on high resolution spectra. Though the large rotation velocity of the star broadens the lines and complicates the analysis, the derived abundances are found fully compatible with those of normal unperturbed stars in NGC 6397, with the exception of a few elements (Li, Ca, and C). The lack of C suggests that the star has been peeled down to regions where incomplete CNO burning occurs, favouring a scenario where the companion is a turn-off star which has lost most of its mass. In addition we found an unexpected large Li abundance, which suggests that fresh 7Li has been produced on the stellar surface.
Key words: Galaxy: globular clusters: individual: NGC 6397 / stars: evolution / stars: abundances / stars: pulsars: individual: PSR J1740-5340 / techniques: spectroscopic
© ESO, 2003
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.