2 research outputs found
MY Camelopardalis, a very massive merger progenitor
Context. The early-type binary MY Cam belongs to the young open cluster
Alicante 1, embedded in Cam OB3. Aims. MY Cam consists of two early-O type
main-sequence stars and shows a photometric modulation suggesting an orbital
period slightly above one day. We intend to confirm this orbital period and
derive orbital and stellar parameters. Methods. Timing analysis of a very
exhaustive (4607 points) light curve indicates a period of 1.1754514 +-
0.0000015 d. High- resolution spectra and the cross-correlation technique
implemented in the TODCOR program were used to derive radial velocities and
obtain the corresponding radial velocity curves for MY Cam. Modelling with the
stellar atmosphere code FASTWIND was used to obtain stellar parameters and
create templates for cross-correlation. Stellar and orbital parameters were
derived using the Wilson-Devinney code, such that a complete solution to the
binary system could be described. Results. The determined masses of the primary
and secondary stars in MY Cam are 37.7 +- 1.6 and 31.6 +- 1.4 Msol,
respectively. The corresponding temperatures, derived from the model atmosphere
fit, are 42 000 and 39 000 K, with the more massive component being hotter.
Both stars are overfilling their Roche lobes, sharing a common envelope.
Conclusions. MY Cam contains the most massive dwarf O-type stars found so far
in an eclipsing binary. Both components are still on the main sequence, and
probably not far from the zero-age main sequence. The system is a likely merger
progenitor, owing to its very short period.Comment: 8 pages, 6 figures, photometric data available on-line, Astronomy and
Astrophysics, 201