Not the most catching of eye candy, is it? The object in the center is SDSS J003615.26+385131.6
, which has gri magnitudes of 23.23, 23.28, and 22.24, respectively; extremely faint, whatever it is.
Zooming out a bit:
Hmm, there seem to be rather a lot of stars, but otherwise nothing to suggest anything worthy of being an OOTD.
The Palomar Transient Factory (Law et al. 2009, Rau et al. 2009) discovered a nova candidate in M31, PTF11fzx, on UT 2011 June 18.50 at RA(J2000)=00:36:15.3, Dec(J2000)=+38:51:31.7. PTF11fzx was R=19.0mag when discovered and fainter than a limiting magnitude of R=20.5 on June 12. The above magnitudes are calibrated to the USNO-B1 catalogue.
Spectra of PTF11fzx were obtained with the Double Beam Spectrograph on the Palomar 200-inch Hale telescope on June 24 and with the Low Resolution Image Spectrometer on the Keck-I telescope on July 2. The P200 spectrum exhibits a blue continuum without prominent Balmer series. The Keck spectrum shows strong Balmer lines (FWHM Halpha ~800 km/s) which are blueshifted by v~-300 km/s, consistent with M31. The existence of Fe II emission lines are indicative of the Fe II spectroscopic class of classical novae (Williams et al. 1994).
This nova is located about 170 arcmin away from the center of M31. Comparing to the Pietsch 2010 compilation, PTF11fzx is the most distant spectroscopically classified classical nova in M31.
That's the contents of ATel #3498
, entitled "PTF discovery and classification of a classical nova in the outskirts of M31
A classical nova is a white dwarf star that is accreting matter (mostly hydrogen) from its close binary companion, usually a red giant. The hydrogen builds up on the white dwarf's surface until it gets dense (and hot) enough to go off like an H-bomb; when it does that, the star brightens a lot, well over a thousand-fold and maybe over a million-fold. A classical nova is one which has been observed to have just one outburst; if there's been more than one, it's called a recurrent nova (both are types of cataclysmic variable - AAVSO, the American Association of Variable Star Observers, which is actually global (despite its name) - has a great page explaining the different types of variables, here
M31, the Andromeda Nebula, has already featured as an OOTD
; here's a DR8 Navigate image that shows the nova's location on its outskirts (you can just see part of the obvious spiral arms in the diagonal purple band at the top):
Now novae in M31 are a dime a dozen; so many, in fact, that the IAU's Central Bureau for Astronomical Telegrams doesn't even send out a notice when one is discovered
As stated elsewhere at this CBAT website, novae in M31 are relatively common (unlike their counterparts in the Magellanic Clouds or the Milky Way, which have only a few observed novae each year). There are roughly a couple dozen novae to be discovered (brighter than about mag 20) in M31 each year [cf., e.g., Capaccioli et al. 1989, A.J. 97, 1622; Hatano et al. 1997, Ap.J. 487, L45; Aguirre 2000, Sky Tel. 99(6), 80]. For this reason, we generally do not announce M31 novae on IAUCs unless they are brighter than about mag 15 or there is spectroscopic confirmation.
So, why make this one an OOTD?
Well, because it's the first M31 nova discovered by zooites!
Zooite robert gagliano posted this just two days' ago: SN Zoo finds Nova in Andromeda Galaxy
Congratulations to zooites aethervox, ahiotis, bentemming, bickaroo, buddyjesus, chrostek, ElisabethB, fergie, GeorLewis, graham d, HelmutU, jwirthig, kaktus9, kiske1, kpax, lpspieler, nilium, robert gagliano, smj, voyager1682002, and WR!!