An HST parallax of the distant cataclysmic variable V1223 Sgr, its system parameters, and accretion rate

Free access article

Issue		A&A Volume 419, Number 1, May III 2004


Page(s)		291 - 299
Section		Stellar structure and evolution
DOI		http://dx.doi.org/10.1051/0004-6361:20034424

A&A 419, 291-299 (2004)
DOI: 10.1051/0004-6361:20034424

An HST parallax of the distant cataclysmic variable V1223 Sgr, its system parameters, and accretion rate

K. Beuermann¹, Th. E. Harrison², B. E. McArthur³, G. F. Benedict³ and B. T. Gänsicke⁴

¹ Universitäts-Sternwarte Göttingen, Geismarlandstr. 11, 37083 Göttingen, Germany
² New Mexico State University, Box 30001/MSC 4500, Las Cruces 88003, Mexico
    e-mail: tharriso@nmsu.edu
³ McDonald Observatory, University of Texas, Austin, 78712 Texas, USA
    e-mail: mca@barney.as.utexas.edu; fritz@astro.as.utexas.edu
⁴ Department of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ, UK
    e-mail: btg@astro.soton.ac.uk

(Received 1 October 2003 / Accepted 10 February 2004 )

Abstract
Using the Hubble space Telescope Fine Guidance Sensor, we have measured the trigonometric parallax of the bright cataclysmic variable 1223 Sgr. The absolute parallax is $\pi_{\rm abs}= 1.96\pm 0.18$ mas, making V1223 Sgr the most distant CV with a well-determined trigonometric parallax. This distance, a Lutz-Kelker correction, and the previously measured extinction yield an absolute visual high-state magnitude $M_{V} =4.0\pm0.2$ . We outline a model, which is consistent with the observed spin-down of the white dwarf and provides for much of the UV/optical emission by reverberation of X-rays. From previous X-ray and UV/optical data, we derive an accretion luminosity $L_{\rm acc}= (2.6\pm0.8)\times 10^{34}$ erg s ^-1, a white dwarf mass $M_1 = 0.93\pm0.12$ $M_{\odot}$ , and an accretion rate $\dot M = (1.4\pm0.3)\times 10^{17}$ g s ^-1,

Key words: astrometry -- stars: individual: V1223 Sgr -- stars: novae, cataclysmic variables

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