2018/11/30 by M. A. Tucker, B. J. Shappee, John P. Wisniewski +1 · 1 citation
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Biology #Component (thermodynamics) #Gamma-ray bursts and supernovae #Physics #Stellar, planetary, and galactic studies #Supernova #Type (biology) #astro-ph.HE #astro-ph.SR
paper · pdf · doi:10.3847/2041-8213/ab0286
7 pages, 4 figures, 1 table, accepted by ApJL
arxiv created 2019/02/12 · openalex publication_date 2019/02/19 · arxiv updated 2019/02/27 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Abstract We analyze a Keck I/Low Resolution Imager and Spectrograph nebular spectrum taken 268 days after B -band maximum of ASASSN-18bt (SN 2018oh), a Type Ia supernova observed by K2 at the time of explosion. ASASSN-18bt exhibited a two-component rise to peak brightness, possibly the signature of an interaction between the supernova ejecta and a large (≳20 R ⊙ ) nearby, non-degenerate companion. We search for emission signatures of stripped material from a non-degenerate companion in the nebular spectrum and find no evidence for any unbound material. We place an upper limit of <0.006 M ⊙ on the amount of stripped/ablated H-rich material that could go undetected in our spectrum, effectively ruling out all hydrogen-rich donor stars. Additionally, we place a more tentative upper limit on He i emission in the observed spectrum of ≲0.02 M ⊙ which also rules out helium star companions. Our deep limits rule out a non-degenerate companion as the explanation for the early-time feature in ASASSN-18bt.