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ATEL #4431      ATEL #4431

Title: NIR Spectrum of SN 2009ip on 2012 Sep 27.3 Confirms Interpretation
as a Type IIn

Author: Adam Burgasser (UCSD), C. Nicholls (UCSD), Miriam Aberasturi
(Centro de Astrobiologia)

Posted: 27 Sep 2012; 19:58 UT

SN 2009ip has undergone significant spectral (Smith & Mauerhan, ATel #4412,
#4427) and photometric (Margutti et al., ATel #4414; Martin et al., ATel
#4416; Brimacombe, ATel #4423; Margutti et al., ATel #4425; Leonard et
al. ATel #4430) changes from LBV-like behavior into an apparent SN explosion.
We report low-resolution (R = 120, delta-V = 2500 km/s) 0.8-2.5 micron
spectroscopy from IRTF/SpeX that confirms the interpretation of this event
as a Type IIn SN.

The source was observed on 2012 Sep 27.3 (8:00-8:30 UT) and found to be
1.8 mag brighter in a broad H+K notch filter than the close source located
5.4" to the NE. Bootstrapping from the Ks > 15.50 magnitude of that source
from 2MASS suggests a magnitude of K ~ 13.7 for SN 2009ip.

The spectral continuum is well-matched to a power law slope log10(f_lam)
= -13.5576 -1.55246 * lam + 0.233246 lam^2, with f_lam in erg/cm2/s/Ang
and lam in microns.  Spectrophotometic colors are I-J = 0.16, J-H =0.22
and H-Ks = 0.26, and spectral flux scaling indicates Ks <~ 13.6 (not accounting
for slit losses)

The primary features in the spectrum are prominent and unresolved H I emission
lines at 1.094 micron (Pa gamma, v width = 2100 km/s), 1.291 micron (Pa
beta, v width = 1600 km/s) and 1.887 micron (Pa alpha, v width = 1100 km/s).
The unresolved lines confirm the near-synchronous optical observations
of Smith & Mauerhan, ATel, #4427, and supports the conclusion that this
event has evolved into a Type IIn.

http://www.astronomerstelegram.org/?read=4431

--
Fidusz (FIDRICH Robert)
drotlevel:fidusz@zpok.hu
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