Bibcode
Elias-Rosa, Nancy; Van Dyk, Schuyler D.; Li, Weidong; Silverman, Jeffrey M.; Foley, Ryan J.; Ganeshalingam, Mohan; Mauerhan, Jon C.; Kankare, Erkki; Jha, Saurabh; Filippenko, Alexei V.; Beckman, J. E.; Berger, Edo; Cuillandre, Jean-Charles; Smith, Nathan
Bibliographical reference
The Astrophysical Journal, Volume 742, Issue 1, article id. 6 (2011).
Advertised on:
11
2011
Journal
Citations
63
Refereed citations
59
Description
We present early- and late-time photometric and spectroscopic
observations of supernova (SN) 2009hd in the nearby spiral galaxy NGC
3627 (M66). This SN is one of the closest to us in recent years and
provides an uncommon opportunity to observe and study the nature of SNe.
However, the object was heavily obscured by dust, rendering it unusually
faint in the optical given its proximity. We find that the observed
properties of SN 2009hd support its classification as a possible Type
II-Linear SN (SN II-L), a relatively rare subclass of core-collapse SNe.
High-precision relative astrometry has been employed to attempt to
identify an SN progenitor candidate, based on a pixel-by-pixel
comparison between Hubble Space Telescope (HST) F555W and F814W images
of the SN site prior to explosion and at late times. A progenitor
candidate is identified in the F814W images only; this object is
undetected in F555W. Significant uncertainty exists in the astrometry,
such that we cannot definitively identify this object as the SN
progenitor. Via insertion of artificial stars into the pre-SN HST
images, we are able to constrain the progenitor's properties to those of
a possible supergiant, with intrinsic absolute magnitude M 0
F555W >~ -7.6 mag and intrinsic color (V -
I)0 >~ 0.99 mag. The magnitude and color limits are
consistent with a luminous red supergiant (RSG); however, they also
allow for the possibility that the star could have been more yellow than
red. From a comparison with theoretical massive-star evolutionary tracks
which include rotation and pulsationally enhanced mass loss, we can
place a conservative upper limit on the initial mass for the progenitor
of M ini <~ 20 M &sun;. If the actual mass of
the progenitor is near the upper range allowed by our derived mass
limit, then it would be consistent with that for the identified
progenitors of the SN II-L 2009kr and the high-luminosity SN II-Plateau
(II-P) 2008cn. The progenitors of these three SNe may possibly bridge
the gap between lower-mass RSGs that explode as SNe II-P and luminous
blue variables, or more extreme RSGs, from which the more exotic SNe
II-narrow may arise. Very late time imaging of the SN 2009hd site may
provide us with more clues regarding the true nature of its progenitor.