Near-infrared spectroscopy of the
young SN Ia in NGC4424
E. Y. Hsiao, M. M
Phillips, N. Morrell, C. Contreras (Las Campanas
Observatory), G. H. Marion (Harvard, CfA), B. F. Madore,
W. L. Freedman, C. R. Burns (Carnegie Observatories), L.
Sturch (Boston University) on behalf of the Carnegie
on 19 May 2012; 15:05 UT
Credential Certification: Eric Hsiao (firstname.lastname@example.org)
Subjects: Infra-Red, Supernovae
We report a near-infrared (NIR)
spectrum obtained of the young SN Ia recently discovered
in NGC 4424, PSN J12271283+0925132 (ATel #4115).
The spectrum was acquired using the FIRE spectrometer on
the 6.5-m Magellan I telescope on May 18.5 UT. We
compare the spectrum to the SpeX spectrum of SN 2011fe (ATel
the earliest NIR spectrum ever obtained for a SN Ia, at
2.6 days past the time of explosion. The line strengths
are noticeably weaker than that of SN 2011fe, indicating
that PSN J12271283+0925132 may be a slow decliner.
Placed at the rest frame of NGC 4424, the minimum of the
Mg II line at 1.0927 micron was measured at ~-15,500
km/s. This velocity is significantly higher in magnitude
than the -13,500 km/s reported for SN 2011fe (ATel #3599);
it is likely the highest velocity ever reported for this
feature. This confirms that PSN J12271283+0925132 is
indeed very young. Continued monitoring of this feature
and better constraints on the explosion date will
determine whether the high velocity is intrinsic to the
SN or an optical depth effect, possibly placing the
spectrum even closer to the time of explosion than the
SpeX spectrum of SN 2011fe. There is no convincing
detection of a C I feature from the FIRE spectrum.