Signatures of circumstellar interaction in the Type IIL supernova ASASSN-15oz

K. Azalee Bostroem*, Stefano Valenti, Assaf Horesh, Viktoriya Morozova, N. Paul M. Kuin, Samuel Wyatt, Anders Jerkstrand, David J. Sand, Michael Lundquist, Mathew Smith, Mark Sullivan, Griffin Hosseinzadeh, Iair Arcavi, Emma Callis, Régis Cartier, Avishay Gal-Yam, Lluís Galbany, Claudia Gutiérrez, D. Andrew Howell, Cosimo InserraErkki Kankare, Kristhell Marisol López, Curtis McCully, Giuliano Pignata, Anthony L. Piro, Ósmar Rodríguez, Stephen J. Smartt, Kenneth W. Smith, Ofer Yaron, David R. Young

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)
112 Downloads (Pure)


Hydrogen-rich, core-collapse supernovae are typically divided into four classes: IIP, IIL, IIn, and IIb. Recent hydrodynamic modelling shows that circumstellar material is required to produce the early light curves of most IIP/IIL supernovae. In this scenario, IIL supernovae experience large amounts of mass-loss before exploding. We test this hypothesis on ASASSN-15oz, a Type IIL supernova. With extensive follow-up in the X-ray, UV, optical, IR, and radio, we present our search for signs of interaction and the mass-loss history indicated by their detection. We find evidence of short-lived intense mass-loss just prior to explosion from light-curve modelling, amounting in 1.5 M of material within 1800 R of the progenitor. We also detect the supernova in the radio, indicating mass-loss rates of 10−6 to 10−7 M yr−1 prior to the extreme mass-loss period. Our failure to detect the supernova in the X-ray and the lack of narrow emission lines in the UV, optical, and NIR do not contradict this picture and place an upper limit on the mass-loss rate outside the extreme period of <10−4 M yr−1. This paper highlights the importance gathering comprehensive data on more Type II supernovae to enable detailed modelling of the progenitor and supernova which can elucidate their mass-loss histories and envelope structures and thus inform stellar evolution models.

Original languageEnglish
Pages (from-to)5120-5141
Number of pages22
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
Early online date26 Feb 2019
Publication statusPublished - Jun 2019


  • Outflows
  • Stars: late-type
  • Stars: winds
  • Supernovae: general
  • Supernovae: individual: ASASSN-15oz
  • Techniques: imaging spectroscopy

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'Signatures of circumstellar interaction in the Type IIL supernova ASASSN-15oz'. Together they form a unique fingerprint.

Cite this