Accretion-disc precession in UX Ursae Majoris
Abstract
We report the results of a long campaign of time series photometry on the nova-like variable UX Ursae Majoris during 2015. It spanned 150 nights, with ∼ 1800 h of coverage on 121 separate nights. The star was in its normal `high state' near magnitude V = 13, with slow waves in the light curve and eclipses every 4.72 h. Remarkably, the star also showed a nearly sinusoidal signal with a full amplitude of 0.44 mag and a period of 3.680 ± 0.007 d. We interpret this as the signature of a retrograde precession (wobble) of the accretion disc. The same period is manifest as a ±33 s wobble in the timings of mid-eclipse, indicating that the disc's centre of light moves with this period. The star also showed strong `negative superhumps' at frequencies ωorb + N and 2ωorb + N, where ωorb and N are, respectively, the orbital and precession frequencies. It is possible that these powerful signals have been present, unsuspected, throughout the more than 60 yr of previous photometric studies.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- April 2016
- DOI:
- 10.1093/mnras/stv3014
- arXiv:
- arXiv:1512.08687
- Bibcode:
- 2016MNRAS.457.1447D
- Keywords:
-
- accretion;
- accretion discs;
- binaries: close;
- stars: individual: UX Ursae Majoris;
- novae;
- cataclysmic variables;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 9 pages, 10 figures, accepted by MNRAS