An Attempt to Spectroscopically Confirm the Suspected Nova in the M31 Globular Cluster Bol 126
ATel #3074; A. W. Shafter (SDSU), R. Ciardullo (PSU), M. J. Darnley, M. F. Bode (Liverpool JMU, UK), K. A. Misselt (U. Arizona)
on 9 Dec 2010; 03:56 UT
Credential Certification: Allen W. Shafter (aws@nova.sdsu.edu)
Subjects: Optical, Nova, Transient
Pietsch et al. (ATel #3013) reported the serendipitous discovery of
a super-soft X-ray source (SSS) coincident with the position of the
M31 globular cluster Bol 126. Shortly thereafter, Henze et al.
(ATel #3019) reviewed archival observations from the Livermore
Optical Transiting Imaging System (Super-LOTIS) and found that Bol 126
had brightened by about one magnitude circa 2010 Oct. 12 UT. Auxiliary
observations indicated the cluster faded roughly to its quiescent
brightness within ~4 days. As pointed out by Henze et al., the observed
brightening of the globular cluster, followed shortly thereafter by the
detection of a SSS coincident with the cluster, is consistent with the
eruption of a rapidly-fading classical nova.
In an attempt to confirm that a nova had in fact erupted within Bol 126,
we obtained spectroscopic observations of the cluster on 2010 Nov. 13.285
with the 9.2m Hobby-Eberly Telescope (+ Marcario Low-Resolution
Spectrograph). The spectrum revealed weak and narrow Balmer and
Mg b λ 516.7, 517.3, 518.3 nm absorption features characteristic of
a globular cluster; but, surprisingly, no obvious Balmer emission that
could be associated with a nova. Although novae typically fade slowly in
H&alpha, Ciardullo et al. (1990, ApJ, 356, 472) have shown that the
fastest novae can fade by as much as 3 mag in Hα over a time
span of a month. Thus, we cannot exclude the possibility that the rapid
optical decline of the nova reduced its spectroscopic signature
below our detection threshold by the time of our observations ~1 month
post eruption.
A.W.S. thanks the NSF for support through AST-0607682 and AST-1009566.