Spectroscopic Confirmation and Classification of the Recent M33 Nova Candidate, M33N 2010-11a

ATel #3063; A. W. Shafter (SDSU), R. Ciardullo (PSU), M. F. Bode, M. J. Darnley (Liverpool JMU, UK), K. A. Misselt (U. Arizona)
on 1 Dec 2010; 23:52 UT
Credential Certification: Allen W. Shafter (aws@nova.sdsu.edu)

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We report spectroscopic observations of the recent M33 nova candidate, M33N 2010-11a, which was discovered by Jiangao Ruan (Fangchenggang, Guangxi, China) and Xing Gao (Urumqi, Xinjiang, China) on 2010 Nov. 27.530 at m~18.6 (unfiltered), and independently by Koichi Nishiyama and Fujio Kabashima (Miyaki-Argenteus Observatory, Japan) approximately a day later on Nov. 28.542 UT. By the time of Nishiyama and Kabashima's observations the object had brightened to m~16.7 (unfiltered). Subsequent observations by T. Yusa (Osaki, Japan) showed that M33N 2010-11a continued to brighten over the following day, reaching m~16.1 (unfiltered) on Nov. 29.064 (CBET #2559).

At our request a spectrum (410–950 nm) of M33N 2010-11a was obtained by Sergey Rostopchin on Dec. 01.052 UT (~4 days post discovery) with the Marcario Low-Resolution Spectrograph on the 9.2m Hobby-Eberly Telescope. The spectrum reveals moderately broad Balmer (FWHM Hα ~ 2800 km/s), Fe II (37,38,42,48,49), and O I λ 777.3, 844.6 nm emission features superimposed on a relatively flat continuum, confirming that M33N 2010-11a is indeed a nova. Lines of helium and nitrogen are either weak or absent in the spectrum, suggesting that M33N 2010-11a is best classified at this time as a moderately-broad-lined Fe II (or Fe IIb) system. Future spectroscopic observations will be required to determine if M33N 2010-11a behaves like some broad-lined Fe II systems and evolves into a He/N nova.

We are grateful to K. Nishiyama and F. Kabashima for quickly bringing the nova candidate to our attention. A.W.S. thanks the NSF for support through AST-0607682 and AST-1009566.