Type Ibn Supernovae Show Photometric Homogeneity and Spectral Diversity at Maximum Light

Journal Article · Sun Feb 19 23:00:00 EST 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/836/2/158· OSTI ID:22663779

Hosseinzadeh, Griffin; Arcavi, Iair; McCully, Curtis; Howell, D. Andrew ^[1]; Valenti, Stefano ^[2]; Johansson, Joel ^[3]; Sollerman, Jesper; Fremling, Christoffer; Karamehmetoglu, Emir ^[4]; Pastorello, Andrea; Benetti, Stefano; Elias-Rosa, Nancy ^[5]; Cao, Yi; Duggan, Gina; Horesh, Assaf ^[6]; Cenko, S. Bradley ^[7]; Clubb, Kelsey I.; Filippenko, Alexei V. ^[8]; Corsi, Alessandra ^[9]; others, and

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1. Las Cumbres Observatory, 6740 Cortona Dr Ste 102, Goleta, CA 93117-5575 (United States)
2. Department of Physics, University of California, 1 Shields Ave, Davis, CA 95616-5270 (United States)
3. Department of Particle Physics and Astrophysics, Weizmann Institute of Science, 76100 Rehovot (Israel)
4. Oskar Klein Centre, Department of Astronomy, Stockholm University, Albanova University Centre, SE-106 91 Stockholm (Sweden)
5. INAF-Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, I-35122 Padova (Italy)
6. Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Mail Code 249-17, Pasadena, CA 91125 (United States)
7. Astrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771 (United States)
8. Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States)
9. Department of Physics, Texas Tech University, Box 41051, Lubbock, TX 79409-1051 (United States)

Type Ibn supernovae (SNe) are a small yet intriguing class of explosions whose spectra are characterized by low-velocity helium emission lines with little to no evidence for hydrogen. The prevailing theory has been that these are the core-collapse explosions of very massive stars embedded in helium-rich circumstellar material (CSM). We report optical observations of six new SNe Ibn: PTF11rfh, PTF12ldy, iPTF14aki, iPTF15ul, SN 2015G, and iPTF15akq. This brings the sample size of such objects in the literature to 22. We also report new data, including a near-infrared spectrum, on the Type Ibn SN 2015U. In order to characterize the class as a whole, we analyze the photometric and spectroscopic properties of the full Type Ibn sample. We find that, despite the expectation that CSM interaction would generate a heterogeneous set of light curves, as seen in SNe IIn, most Type Ibn light curves are quite similar in shape, declining at rates around 0.1 mag day{sup −1} during the first month after maximum light, with a few significant exceptions. Early spectra of SNe Ibn come in at least two varieties, one that shows narrow P Cygni lines and another dominated by broader emission lines, both around maximum light, which may be an indication of differences in the state of the progenitor system at the time of explosion. Alternatively, the spectral diversity could arise from viewing-angle effects or merely from a lack of early spectroscopic coverage. Together, the relative light curve homogeneity and narrow spectral features suggest that the CSM consists of a spatially confined shell of helium surrounded by a less dense extended wind.

• OSTI ID: 22663779
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 836; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
EMISSION
EXCEPTIONS
EXPLOSIONS
HELIUM
HYDROGEN
INFRARED SPECTRA
INTERACTIONS
STELLAR WINDS
SUPERNOVAE
TYPE I SUPERNOVAE
VISIBLE RADIATION