AAVSO: American Association of Variable Star Observers

Last Rites for Cataclysmic Variables: Death by Fire, or Ice? (Abstract)

Volume 44 number 1 (2016)

Joseph Patterson
Center for Backyard Astrophysics, 25 Claremont Avenue, Apt. 7C, New York, NY 10027; jop@astro.columbia.edu


(Abstract only) Cataclysmic binaries lose angular momentum as they age, and thus the component stars in the binary spiral ever closer together. As the spiraling-in proceeds, the shrinking Roche lobe “strangles” the donor star, forcing it to transfer mass. Since we can measure the rate of mass transfer pretty well, we know the rate of angular momentum loss pretty well. But when we calculate this we find that CVs reach the end of the line after about one billion years. That’s too soon! It implies that there should be an old-age home somewhere for CVs, where the stars look discernibly different from the working-age population that we know about. Does this class exist? Many students of this problem think that the answer is probably yes, although so far we have not found a single confirmed example. Of course, CVs also suffer classical-nova and dwarf-nova eruptions. It’s assumed that these are of little consequence, because they are just transient blips in the overall evolution. We have discovered some evidence that this assumption may be false—that CVs may actually end their lives in a paroxysm of nova outbursts. In this picture, every star will become a T Pyx; we only know of one because the timescale of this final phase of self-destruction is so short.