Near-IR observations of Nova Oph 2015
ATel #7446; D. P. K. Banerjee, N. M. Ashok, V. Venkataraman and M. Srivastava (Physical Research Laboratory, Ahmedabad, India)
on 26 Apr 2015; 07:56 UT
Credential Certification: Dipankar P.K. Banerjee (orion@prl.res.in)
Subjects: Infra-Red, Nova
Referred to by ATel #: 8142
We report NIR spectra of Nova Oph 2015, discovered on March 29.766 UT, using the NIR camera/spectrograph (NICS)
and the 1.2m Mount Abu telescope. This nova has shown He/N characteristics during the climb to maximum (ATel #7339)
but had reverted to a Fe II class around maximum (ATel #7367; see spectrum description of April 11 ). Our
spectra of 19, 21 and 25 April, at R ~ 1000 show the following traits. On 19 and 21 April the spectra are basically of the FeII class but
the HeI 1.0831 and 2.0581 micron lines are unusually strong for a FeII type of nova.
It is rare to see in a Fe II nova, so early during the decline phase, that the HeI 1.0831 and He 2.0581 lines
are as strong as or stronger than Paschen beta (1.2818 micron) and Brackett
gamma 2.1656 micron) respectively. In the April 25 spectrum, the He line strengths have suddenly dropped
and they are now considerably weaker than the H recombination lines referred to above.
Nova Oph 2015 is thus showing interesting developments. and seemingly an anomalous behavior, which
warrants further observations. The HI lines are presently showing double peaked profiles
compared to the sharply-peaked profiles reported earlier (ATel #7339). The Lyman beta
fluoresced OI 1.1287 micron line is strong and several CI lines are prominently present.
