Extensive optical and near-infrared observations of the nearby, narrow-lined type Ic SN 2007gr: days 5 to 415

• Published in: Astronomy & Astrophysics
• Main Authors: Hunter, D. J., Valenti, S., Kotak, R., Meikle, W. P. S., Taubenberger, S., Pastorello, A., Benetti, S., Stanishev, V., Smartt, S. J., Trundle, C., Arkharov, A. A., Bufano, F., Cappellaro, E., Di Carlo, E., Dolci, M., Elias-Rosa, N., Frandsen, S., Fynbo, J. U., Hopp, U., Larionov, V. M., Laursen, P., Mazzali, P., Navasardyan, H., Ries, C., Riffeser, A., Rizzi, L., Tsvetkov, D. Y., Turatto, M., Wilke, S.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: EDP Sciences 2009
• Subjects: supernovae: individual: SN 2007gr; techniques: miscellaneous; supernovae: individual: SN 2002ap; supernovae: general; Gemini; Norway; Iceland
• Online Access: https://doi.org/10.1051/0004-6361/200912896

We present photometric and spectroscopic observations at optical and near-infrared wavelengths of the nearby type Ic supernova 2007gr. These represent the most extensive data-set to date of any supernova of this sub-type, with frequent coverage from shortly after discovery to more than one year post-explosion. We deduce a rise time to B-band maximum of 11.5 ± 2.7 d. We find a peak B-band magnitude of M_B = −16.8, and light curves which are remarkably similar to the so-called "hypernova" SN 2002ap. In contrast, the spectra of SNe 2007gr and 2002ap show marked differences, not least in their respective expansion velocities. We attribute these differences primarily to the density profiles of their progenitor stars at the time of explosion i.e. a more compact star for SN 2007gr compared to SN 2002ap. From the quasi-bolometric light curve of SN 2007gr, we estimate that 0.076 ± 0.010 M_⊙ of ^(56)Ni was produced in the explosion. Our near-infrared (IR) spectra clearly show the onset and disappearance of the first overtone of carbon monoxide (CO) between ~70 to 175 d relative to B-band maximum. The detection of the CO molecule implies that ionised He was not microscopically mixed within the carbon/oxygen layers. From the optical spectra, near-IR light curves, and colour evolution, we find no evidence for dust condensation in the ejecta out to about +400 d. Given the combination of unprecedented temporal coverage, and high signal-to-noise data, we suggest that SN 2007gr could be used as a template object for supernovae of this sub-class. © ESO 2009. Received 15 July 2009. Accepted 17 September 2009. Published online 24 September 2009. We would like to thank all the staff from the Asiago Ekar Telescope, Campo Imperatore Telescope, Calar Alto Observatory, Gemini North Telescope, Nordic Optical Telescope (operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden), Osservatorio di Teramo, Sternberg Astronomical Institute Telescope, Telescopio Nazionale Galileo, UKIRT, and the ...