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Published November 20, 2011 | Published
Journal Article Open

The Massive Progenitor of the Possible Type II-Linear Supernova 2009hd in Messier 66

Abstract

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_☉. 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.

Additional Information

© 2011 The American Astronomical Society. Received 2010 November 9; accepted 2011 August 12; published 2011 October 28. This research is based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under NASA contract NAS 05-26555; the SMARTS Consortium 1.3 m telescope located at Cerro Tololo Inter-American Observatory (CTIO), Chile; the 1.5 m telescope located at Palomar Observatory; the Liverpool Telescope operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias with financial support from the UK Science and Technology Facilities Council; the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias; the 6.5 m Magellan Clay and Baade telescopes located at Las Campanas Observatory, Chile; and the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, with generous financial support from the W. M. Keck Foundation. We are grateful to the staffs at these observatories for their excellent assistance with the observations. N.E.R. thanks Stefano Benetti and Alberto Noriega-Crespo for useful discussions and Avet Harutyunyan for his help. Many of the spectra used here for comparison were obtained from the Padova-Asiago Supernova Archive (ASA). This work has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. This work has been supported by the MICINN grant AYA08-1839/ESP, by the ESF EUROCORES Program EuroGENESIS (MICINN grant EUI2009-04170), by SGR grants of the Generalitat de Catalunya, and by EU-FEDER funds. The research of A.V.F.'s supernova group has been generously supported by National Science Foundation grant AST-0908886 and the TABASGO Foundation, as well as by NASA through grants AR-11248, AR-12126, and GO-11575 from the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555. Facilities: HST (WFPC2), HST (ACS), CTIO:1.3m (SMARTS), PO:1.5m, Hale (TripleSpec), Liverpool:2m (RATCam), NOT (ALFOSC), Magellan:Baade (IMACS), Magellan:Clay (MagE), Keck:II (DEIMOS)

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August 22, 2023
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