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|Title:||Massive stars exploding in a He-rich circumstellar medium - V. Observations of the slow-evolving SN Ibn OGLE-2012-SN-006||Authors:||PASTORELLO, Andrea
Prieto, J. L.
ELIAS DE LA ROSA, NANCY DEL CARMEN
Anderson, J. P.
BOTTICELLA, MARIA TERESA
Graham, M. L.
Howell, D. A.
Smartt, S. J.
Smith, K. W.
Young, D. R.
Szymański, M. K.
|Issue Date:||2015||Journal:||MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY||Number:||449||Issue:||2||First Page:||1941||Abstract:||We present optical observations of the peculiar Type Ibn supernova (SN Ibn) OGLE-2012-SN-006, discovered and monitored by the Optical Gravitational Lensing Experiment-IV survey, and spectroscopically followed by Public ESO Spectroscopic Survey of Transient Objects (PESSTO) at late phases. Stringent pre-discovery limits constrain the explosion epoch with fair precision to JD = 245 6203.8 ± 4.0. The rise time to the I-band light-curve maximum is about two weeks. The object reaches the peak absolute magnitude M<SUB>I</SUB> = -19.65 ± 0.19 on JD = 245 6218.1 ± 1.8. After maximum, the light curve declines for about 25 d with a rate of 4 mag (100 d)<SUP>-1</SUP>. The symmetric I-band peak resembles that of canonical Type Ib/c supernovae (SNe), whereas SNe Ibn usually exhibit asymmetric and narrower early-time light curves. Since 25 d past maximum, the light curve flattens with a decline rate slower than that of the <SUP>56</SUP>Co-<SUP>56</SUP>Fe decay, although at very late phases it steepens to approach that rate. However, other observables suggest that the match with the <SUP>56</SUP>Co decay rate is a mere coincidence, and the radioactive decay is not the main mechanism powering the light curve of OGLE-2012-SN-006. An early-time spectrum is dominated by a blue continuum, with only a marginal evidence for the presence of He I lines marking this SN type. This spectrum shows broad absorptions bluewards than 5000 Å, likely O II lines, which are similar to spectral features observed in superluminous SNe at early epochs. The object has been spectroscopically monitored by PESSTO from 90 to 180 d after peak, and these spectra show the typical features observed in a number of SN 2006jc-like events, including a blue spectral energy distribution and prominent and narrow (v<SUB>FWHM</SUB> ≈ 1900 km s<SUP>-1</SUP>) He I emission lines. This suggests that the ejecta are interacting with He-rich circumstellar material. The detection of broad (10<SUP>4</SUP> km s<SUP>-1</SUP>) O I and Ca II features likely produced in the SN ejecta (including the [O I] λλ6300,6364 doublet in the latest spectra) lends support to the interpretation of OGLE-2012-SN-006 as a core-collapse event.||Acknowledgments:||We would like to thank the anonymous referee for providing us with constructive comments and suggestions. AP, EC, SB and MT are partially supported by the PRIN-INAF 2011 with the project ‘Transient Universe: from ESO Large to PESSTO’. NER acknowledges the support from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 267251 Astronomy Fellowships in Italy (AstroFIt). AMG acknowledges financial support by the MICINN grant AYA2011-24704/ESP, by the ESF EUROCORES Program EuroGENESIS (MINECO grants EUI2009-04170), SGR grants of the Generalitat de Catalunya and by the EU-FEDER funds. This work was partially supported by the Polish Ministry of Science and Higher Education through the program ‘Ideas Plus award no. IdP2012 000162. SS acknowledges support from CONICYT-Chile FONDECYT 3140534, Basal-CATA PFB-06/2007, and Project IC120009 ‘Millennium Institute of Astrophysics (MAS)’ of Iniciativa Científica Milenio del Ministerio de Economía, Fomento y Turismo. Research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013)/ERC Grant agreement no.  (PI: SJS) and EU/FP7-ERC grant no.  (PI: AG-Y). AG-Y is also supported by The Quantum Universe I-Core programme by the Israeli Committee for planning and funding and the ISF, a GIF grant, and the Kimmel award. The OGLE project has received funding from the European Research Council under the European Community's Seventh Framework Programme (FP7/2007- 2013)/ERC grant agreement no. 246678 to AU. This work is partially supported by the Polish Ministry of Science and Higher Education program “Ideas Plus” no. IdP2012 000162, and is also partly supported by the European Union FP7 programme through ERC grant number 320360. This work is partially based on observations obtained under the ESO-NTT Large Program 188.D-3003 (PESSTO). This work makes use of observations from the LCOGT network, the 1.3-m Warsaw University Telescope and the 2.5-m du Pont Telescope at the LCO, the 2.2-m MPI/ESO Telescope and the 3.58-m ESO NTT at ESO-La Silla. We thank Jonathan Elliott (MPE Garching) for executing the GROND observation. AP thanks M. L. Pumo for useful discussions. Part of the funding for GROND (both hardware as well as personnel) was generously granted from the Leibniz-Prize to Professor G. Hasinger (DFG grant HA 1850/28-1). This publication makes use of data products from the 2MASS, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration (NASA) and the National Science Foundation. This research 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 the NASA. We acknowledge the usage of the HyperLeda data base ( http://leda.univ-lyon1.fr ).||URI:||http://hdl.handle.net/20.500.12386/23899||URL:||https://academic.oup.com/mnras/article/449/2/1941/1062344||ISSN:||0035-8711||DOI:||10.1093/mnras/stu2621||Bibcode ADS:||2015MNRAS.449.1941P||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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