On the ultracompact nature of 4U1822-000
Abstract
We report the discovery of a periodic modulation in the optical lightcurve of the candidate ultracompact X-ray binary 4U1822-000. Using time-resolved optical photometry taken with the William Herschel Telescope we find evidence for a sinusoidal modulation with a semi-amplitude of 8 per cent and a period of 191min, which is most likely close to the true orbital period of the binary. Using the van Paradijs & McClintock relation for the absolute magnitude and the distance modulus allowing for interstellar reddening, we estimate the distance to 4U1822-000 to be 6.3kpc. The long orbital period casts severe doubts on the ultracompact nature of 4U1822-000.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- April 2007
- DOI:
- 10.1111/j.1365-2966.2007.11579.x
- arXiv:
- arXiv:astro-ph/0701915
- Bibcode:
- 2007MNRAS.376.1886S
- Keywords:
-
- accretion;
- accretion discs;
- binaries: close;
- stars: individual: 4U1822-000;
- Astrophysics
- E-Print:
- 3 pages, 1 figure, accepted by MNRAS