2013ApJ...767...71M
Multi-wavelength Observations of Supernova 2011ei: Time-dependent Classification of Type IIb and Ib Supernovae and Implications for Their Progenitors
Milisavljevic, Dan ( Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA ); Margutti, Raffaella ( Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA ); Soderberg, Alicia M. ( Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA ); Pignata, Giuliano ( Departamento de Ciencias Fisicas, Universidad Andres Bello, Avda. Republica 252, Santiago, Chile ); Chomiuk, Laura ( Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA; National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801, USA ); Fesen, Robert A. ( Department of Physics & Astronomy, Dartmouth College, 6127 Wilder Lab, Hanover, NH 03755, USA ); Bufano, Filomena ( Departamento de Ciencias Fisicas, Universidad Andres Bello, Avda. Republica 252, Santiago, Chile ); Sanders, Nathan E. ( Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA ); Parrent, Jerod T. ( Department of Physics & Astronomy, Dartmouth College, 6127 Wilder Lab, Hanover, NH 03755, USA; Las Cumbres Observatory Global Telescope Network, Goleta, CA 93117, USA ); Parker, Stuart ( Parkdale Observatory, 225 Warren Road, RDl Oxford, Canterbury 7495, New Zealand ); Mazzali, Paolo ( Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Strasse 1, D-85748 Garching, Germany ; INAF-Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, I-35122 Padova, Italy ; Kavli Institute for Theoretical Physics, Kohn Hall, University of California at Santa Barbara, Santa Barbara, CA 93106-4030, USA ); Pian, Elena ( Kavli Institute for Theoretical Physics, Kohn Hall, University of California at Santa Barbara, Santa Barbara, CA 93106-4030, USA ; INAF, Trieste Astronomical Observatory, Via G. B. Tiepolo 11, I-34143 Trieste, Italy ; Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy ); Pickering, Timothy ( South African Astronomical Observatory, P.O. Box 9, Observatory 7935, Cape Town, South Africa ; Southern African Large Telescope, P.O. Box 9, Observatory 7935, Cape Town, South Africa ); Buckley, David A. H. ( South African Astronomical Observatory, P.O. Box 9, Observatory 7935, Cape Town, South Africa ; Southern African Large Telescope, P.O. Box 9, Observatory 7935, Cape Town, South Africa ); Crawford, Steven M. ( South African Astronomical Observatory, P.O. Box 9, Observatory 7935, Cape Town, South Africa ; Southern African Large Telescope, P.O. Box 9, Observatory 7935, Cape Town, South Africa ); Gulbis, Amanda A. S. ( South African Astronomical Observatory, P.O. Box 9, Observatory 7935, Cape Town, South Africa ; Southern African Large Telescope, P.O. Box 9, Observatory 7935, Cape Town, South Africa ); Hettlage, Christian ( South African Astronomical Observatory, P.O. Box 9, Observatory 7935, Cape Town, South Africa ; Southern African Large Telescope, P.O. Box 9, Observatory 7935, Cape Town, South Africa ); Hooper, Eric ( Department of Astronomy, University of Wisconsin, Madison, WI 53706, USA ); Nordsieck, Kenneth H. ( Department of Astronomy, University of Wisconsin, Madison, WI 53706, USA ); O'Donoghue, Darragh ( Southern African Large Telescope, P.O. Box 9, Observatory 7935, Cape Town, South Africa ); Husser, Tim-Oliver ( Institut für Astrophysik, Georg-August-Universität, Friedrich-Hund-Platz 1, D-37077 Göttingen, Germany ); Potter, Stephen ( South African Astronomical Observatory, P.O. Box 9, Observatory 7935, Cape Town, South Africa ); Kniazev, Alexei ( South African Astronomical Observatory, P.O. Box 9, Observatory 7935, Cape Town, South Africa; Southern African Large Telescope, P.O. Box 9, Observatory 7935, Cape Town, South Africa ); Kotze, Paul ( South African Astronomical Observatory, P.O. Box 9, Observatory 7935, Cape Town, South Africa; Southern African Large Telescope, P.O. Box 9, Observatory 7935, Cape Town, South Africa ); Romero-Colmenero, Encarni ( South African Astronomical Observatory, P.O. Box 9, Observatory 7935, Cape Town, South Africa; Southern African Large Telescope, P.O. Box 9, Observatory 7935, Cape Town, South Africa ); Vaisanen, Petri ( South African Astronomical Observatory, P.O. Box 9, Observatory 7935, Cape Town, South Africa; Southern African Large Telescope, P.O. Box 9, Observatory 7935, Cape Town, South Africa ); Wolf, Marsha ( Department of Astronomy, University of Wisconsin, Madison, WI 53706, USA ); Bietenholz, Michael F. ( Department of Physics and Astronomy, York University, Toronto, Ontario M3J 1P3, Canada ; Hartebeesthoek Radio Observatory, P.O. Box 443, Krugersdorp 1740, South Africa ); Bartel, Norbert ( Department of Physics and Astronomy, York University, Toronto, Ontario M3J 1P3, Canada ); Fransson, Claes ( Department of Astronomy, The Oskar Klein Centre, Stockholm University, SE-10691 Stockholm, Sweden ); Walker, Emma S. ( Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy ); Brunthaler, Andreas ( National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801, USA ; Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany ); Chakraborti, Sayan ( Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai 400005, India ); Levesque, Emily M. ( CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, 389-UCB, Boulder, CO 80309, USA ); MacFadyen, Andrew ( Department of Physics, New York University, 4 Washington Place, New York, NY 10003, USA ); Drescher, Colin ( PO Box 1555, Sunnybank Hills 4109, Queensland, Australia ); Bock, Greg ( Windaroo Lakes Observatory, 2 Anna-Louise Terrace, Windaroo, Queensland, Australia ); Marples, Peter ( Loganholme Observatory, 45 Kiewa Drive, Loganholme, Queensland, Australia ); Anderson, Joseph P. ( Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago, Chile ); Benetti, Stefano ( INAF-Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, I-35122 Padova, Italy ); Reichart, Daniel ( Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Campus Box 3255, Chapel Hill, NC 27599-3255, USA ); Ivarsen, Kevin ( Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Campus Box 3255, Chapel Hill, NC 27599-3255, USA ) and 32 coauthors show affiliations
The Astrophysical Journal, Volume 767, Issue 1, article id. 71, 19 pp. (2013).
Published in Apr 2013
We present X-ray, UV/optical, and radio observations of the stripped-envelope, core-collapse supernova (SN) 2011ei, one of the least luminous SNe IIb or Ib observed to date. Our observations begin with a discovery within ~1 day of explosion and span several months afterward. Early optical spectra exhibit broad, Type II-like hydrogen Balmer profiles that subside rapidly and are replaced by Type Ib-like He-rich features on a timescale of one week. High-cadence monitoring of this transition suggests absorption attributable to a high-velocity (gsim 12, 000 km s-1) H-rich shell, which is likely present in many Type Ib events. Radio observations imply a shock velocity of v ≈ 0.13 c and a progenitor star average mass-loss rate of \dot{M}≈ 1.4 × 10^{-5} M_{☉} yr^{-1} (assuming wind velocity vw = 103 km s-1). This is consistent with independent constraints from deep X-ray observations with Swift-XRT and Chandra. Overall, the multi-wavelength properties of SN 2011ei are consistent with the explosion of a lower-mass (3-4 M ), compact (R * <~ 1 × 1011 cm), He-core star. The star retained a thin hydrogen envelope at the time of explosion, and was embedded in an inhomogeneous circumstellar wind suggestive of modest episodic mass loss. We conclude that SN 2011ei's rapid spectral metamorphosis is indicative of time-dependent classifications that bias estimates of the relative explosion rates for Type IIb and Ib objects, and that important information about a progenitor star's evolutionary state and mass loss immediately prior to SN explosion can be inferred from timely multi-wavelength observations.
Keywords:
Free Keywords: Astrophysics - High Energy Astrophysical Phenomena; supernovae: general; supernovae: individual: SN 2011ei
Astronomy: supernovae: general; supernovae: individual: SN 2011ei
arXiv: Astrophysics - High Energy Astrophysical Phenomena
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