The fight for accretion: discovery of intermittent mass transfer in BB Doradus in the low state
P. Rodr\'iguez-Gil (1,2,3), L. Schmidtobreick (4), K. S. Long (5), B., T. G\"ansicke (6), M. A. P. Torres (7,8), M. M. Rubio-D\'iez (9), M., Santander-Garc\'ia (10) ((1) Departamento de Astrof\'isica, Universidad de La, Laguna, Tenerife, Spain

TL;DR
This study reveals that in the low state of BB Doradus, episodic accretion occurs, indicating that accretion is not entirely halted, and provides new orbital parameters and insights into the accretion mechanisms involved.
Contribution
First spectroscopic analysis of BB Doradus in its low state showing episodic accretion and proposing two possible mechanisms for the observed emission features.
Findings
Detected episodic accretion events in the low state.
Measured orbital period of 0.154095 days.
Identified potential accretion mechanisms involving a remnant disc or magnetic activity.
Abstract
Our long-term photometric monitoring of southern nova-like cataclysmic variables with the 1.3-m SMARTS telescope found BB Doradus fading from V ~ 14.3 towards a deep low state at V ~ 19.3 in April 2008. Here we present time-resolved optical spectroscopy of BB Dor in this faint state in 2009. The optical spectrum in quiescence is a composite of a hot white dwarf with Teff = 30000 +- 5000 K and a M3-4 secondary star with narrow emission lines (mainly of the Balmer series and HeI) superposed. We associate these narrow profiles with an origin on the donor star. Analysis of the radial velocity curve of the H-alpha emission from the donor star allowed the measurement of an orbital period of 0.154095 +- 0.000003 d (3.69828 +- 0.00007 h), different from all previous estimates. We detected episodic accretion events which veiled the spectra of both stars and radically changed the line profiles…
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