Variable Hα Emission in the Nebular Spectra of the Low-luminosity Type Ia SN2018cqj/ATLAS18qtd

Jose L. Prieto, Ping Chen, Subo Dong, S. Bose, A. Gal-Yam, T. W-S Holoien, J. A. Kollmeier, M. M. Phillips, B. J. Shappee

Research output: Contribution to journalArticlepeer-review

Abstract

We present optical photometry and spectroscopy of the Type Ia supernova SN2018cqj/ATLAS18qtd. The supernova exploded in an isolated region at ∼65 kpc from the S0 galaxy IC 550 at z = 0.0165 (D ≈ 74 Mpc) and has a redshift consistent with a physical association to this galaxy. Multicolor photometry show that SN2018cqj/ATLAS18qtd is a low-luminosity (M B&max;-17.9 mag), fast-declining Type Ia, with color stretch s BV ≈ 0.6 and B-band decline rate Δm 15(B) ≈ 1.77 mag. Two nebular-phase spectra obtained as part of the 100IAS survey at +193 and +307 days after peak show the clear detection of a narrow Hα line in emission that is resolved in the first spectrum with FWHM ≈ 1200 km s -1 and L ≈ 3.8 × 10 37 erg s -1. The detection of a resolved Hα line with a declining luminosity is broadly consistent with recent models where hydrogen is stripped from the nondegenerate companion in a single-degenerate progenitor system. However, the amount of hydrogen consistent with the luminosities of the Hα line would be ∼10 -3 M o˙, which is significantly less than theoretical model predictions in the classical single-degenerate progenitor systems. SN2018cqj/ATLAS18qtd is the second low-luminosity, fast-declining SN Ia after SN2018fhw/ASASSN-18tb that shows narrow Hα in emission in its nebular-phase spectra.

Original languageEnglish
Article number100
Number of pages8
JournalAstrophysical Journal
Volume889
Issue number2
Early online date29 Jan 2020
DOIs
StatePublished - 1 Feb 2020

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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