23 October 2003

Speaker: Janet Drew (Imperial College London)

Title: A binary taxonomy brain-teaser: the first carbon-enhanced cataclysmic variable

Abstract: Inspired by the extraordinary profusion of species and adaptational variety, J. B. S. Haldane claimed that God has `an inordinate fondness for beetles'. Well, binaries are the coleoptera of astrophysics, with the interacting kind particularly prone to variety. In this talk, I shall describe recent and continuing work on QU Car, a bright (11th magnitude) interacting binary, containing a WD accretor. Although known for over 30 years it was, until recently, studied little. It has now emerged as the first example of an emphatically carbon-rich short-period (P =0.459 d) system -- in which mass is being transferred at, most probably, a very high rate. Hitherto, abundance anomalies among obviously related objects have always been nitrogen enhancements. Its evolutionary status is quite unclear, but the properties of this binary may pose a challenge to views on nova activity and pathways to SN Ia. I will end the talk with a brief advert for a newly-started Galactic Plane survey that has the potential to trawl for many more weird and weirder emission line objects.

References for students:

1. Hartley L. E., Drew, J. E., Long, K. S. 2002, MNRAS, 336, 808
2. Drew, J. E., Hartley L. E., Long K. S., van der Walt J. 2003, MNRAS, 338, 401
3. Schmidtobreick L., Tappert C., Bianchini A., Mennickent R. E., 2003, AA, in press (astro-ph/0309479: on a newly-recovered nova showing evidence for carbon enrichment also)
4. Cowley A. P., Schmidtke P. C., Crampton D., Hutchings J. B. 1998, ApJ, 504, 854 (on the optical properties of supersoft X-ray binaries, a possibly related group of objects)