EDP Sciences
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Volume 407, Number 1, August III 2003
Page(s) 325 - 334
Section Stellar atmospheres
DOI http://dx.doi.org/10.1051/0004-6361:20030835

A&A 407, 325-334 (2003)
DOI: 10.1051/0004-6361:20030835

The nature of the Cepheid T Antliae

D. G. Turner1 and L. N. Berdnikov2

1  Department of Astronomy and Physics, Saint Mary's University, Halifax, Nova Scotia B3H 3C3, Canada
2  Sternberg Astronomical Institute and Isaac Newton Institute of Chile, Moscow Branch, 13 Universitetskij prosp., Moscow 119899, Russia
    e-mail: berdnik@sai.msu.ru

(Received 7 April 2003 / Accepted 21 May 2003 )

The variable star T Antliae, sometimes suspected to be a type II pulsator, is demonstrated to be a classical Cepheid in the third crossing of the instability strip. It exhibits a positive period change of  $+0.514 \pm 0.016$ s yr -1, consistent with a star on the blue side of the instability strip and evolving through it for the third time. The Cepheid exhibits no random fluctuations in pulsation period, although superimposed upon its evolutionary O-C trend are very subtle variations that may be indicative of orbital motion about an unseen companion. Archival spectroscopic data also indicate that the star sits on the edge of a putative cluster of B-type stars that may be physically associated with the Cepheid. Additional photometric and spectroscopic data for the Cepheid and cluster are needed to strengthen the case. The field reddening of T Ant established from nearby early-type stars is $E_{B-V}=0.30 \pm 0.01$ ( $E_{B-V}{\rm (B0)}=0.316 \pm 0.014$).

Key words: stars: distances -- stars: variables: Cepheids -- Galaxy: open clusters and associations: individual: T Ant

Offprint request: D. G. Turner, turner@ap.smu.ca

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