[Date Prev][Date Next][Date Index]

(cba:news) AA Dor and T Pyx (Joe Patterson) [2017-12-10T12:05:08Z]


Hi CBAers,

I'm getting close to finishing the IM Nor paper. Only a few CBAers contributed to this one (Gordon, Berto, and Paul Warhurst so far); it's very faint, far southern, and obscure - discouragements to most of us.

This paper will go into some detail concerning the irradiation of the donor star by the hot white dwarf, in the aftermath of a nova explosion. I would like to include light curves from a classic supersoft binary and a classic hot-subdwarf binary - stars in which heating effects are truly obvious and well-known. It's hard to convince people of the importance of heating in CVs; some think it's obvious, and others think it's impossible. And I think there's a third group ("maybe true but of no importance").

AA Dor is a very famous star with a beautiful light curve - primary eclipse, secondary eclipse, and sinusoidal wave obviously signifying the heating of the brown-dwarf secondary by the hot-subdwarf primary. It has been analyzed in great detail - it competes with HW Vir as the prototype of the class (sort of like SS Cyg and U Gem battling for the honors among dwarf novae).

CBA light curves of AA Dor would be a nice addition to our paper. We already have a beautiful orbital light curve of a supersoft (QR And), and AA Dor would bookend it nicely. It would be a nice primer on heating effects - in a detached binary (AA Dor) and a full accretion-disk system (QR And). At magnitude 11.5, AA Dor is blindingly bright; I recommend a V filter if you have one you like - although unfiltered is OK too if you scrupulously avoid large airmass. As befits a simple star, 6 hours is both the binary period and the right ascension. Nice holiday gift.

     Ali is the greatest,
     But now hear the latest:
     AA Dor
     Is what we wish for.

The holidays have also brought T Pyx back in the sky. Let's get going on this star. Southern USA observers can contribute, as well as - obviously - the australites. Each new season brings peril to our favorite theory: death by heating.

joe p


____________________________________________________________
Center for Backyard Astrophysics (CBA) mailing lists
http://cbastro.org/communications/mailing-lists/