# Constraining the Mass Loss Geometry of Beta Lyrae

• Lomax, Jamie R. (Department of Physics and Astronomy, University of Denver)
• Accepted : 2012.01.07
• Published : 2012.03.15

#### Abstract

Massive binary stars lose mass by two mechanisms: jet-driven mass loss during periods of active mass transfer and by wind-driven mass loss. Beta Lyrae is an eclipsing, semi-detached binary whose state of active mass transfer provides a unique opportunity to study how the evolution of binary systems is affected by jet-driven mass loss. Roche lobe overflow from the primary star feeds the thick accretion disk which almost completely obscures the mass-gaining star. A hot spot predicted to be on the edge of the accretion disk may be the source of beta Lyrae's bipolar outflows. I present results from spectropolarimetric data taken with the University of Wisconsin's Half-Wave Spectropolarimeter and the Flower and Cook Observatory's photoelastic modulating polarimeter instrument which have implications for our current understanding of the system's disk geometry. Using broadband polarimetric analysis, I derive new information about the structure of the disk and the presence and location of a hot spot. These results place constraints on the geometrical distribution of material in beta Lyrae and can help quantify the amount of mass lost from massive interacting binary systems during phases of mass transfer and jet-driven mass loss.

#### References

1. Ak H, Chadima P, Harmanec P, Demicran O, Yang S, et al., New findings supporting the presence of a thick disc and bipolar jets in the $\beta$ Lyrae system, A&A, 463, 233-241 (2007). http://dx.doi.org/10.1051/0004-6361:20065536 https://doi.org/10.1051/0004-6361:20065536
2. Appenzeller I, Hiltner WA, True polarization curves for beta Lyrae, AJ, 149, 353-362 (1967). http://dx.doi.org/ 10.1086/149258 https://doi.org/10.1086/149258
3. Harmanec P, Morand F, Bonneau D, Jiang Y, Yang S, et al., Jet-like structures in $\beta$ Lyrae. Results of optical interferometry, spectroscopy and photometry, A&A, 312, 879-896 (1996).
4. Harmanec P, Scholz G, Orbital elements of beta Lyrae after the first 100 years of investigation, A&A, 279, 131-147 (1993).
5. Hoffman JL, Nordsieck KH, Fox GK, Spectropolarimetric evidence for a bipolar flow in beta Lyrae, AJ, 115, 1576-1591 (1998). http://dx.doi.org/10.1086/300274 https://doi.org/10.1086/300274
6. Hubeny I, Plavec MJ, Can a disk model explain beta Lyrae?, AJ, 102, 1156-1170 (1991). http://dx.doi.org/10.1086/115942 https://doi.org/10.1086/115942
7. Lomax JR, Hoffman JL, Elias NM Jr, Bastien FA, Holenstein BD, Geometrical constraints on the hot spot and bipolar outflows in beta Lyrae, ApJ submitted (2011). http://arxiv.org/abs/1108.3015
8. Lubow SH, Shu FH, Gas dynamics of semidetached binaries, AJ, 198, 383-405 (1975). http://dx.doi.org/10.1086/153614 https://doi.org/10.1086/153614
9. Zhao M, Gies D, Monnier JD, Thureau N, Pedretti E, et al., First resolved images of the eclipsing and interacting binary $\beta$ Lyrae, ApJ, 684, L95-L98 (2008). http://dx.doi.org/ 10.1086/592146 https://doi.org/10.1086/592146