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Abstract We present photometric and spectroscopic data for the nearby Type I supernova (SN Ia) 2019eix (originally classified as an SN Ic), from the day of its discovery up to 100 days after maximum brightness. Before maximum light, SN 2019eix resembles a typical SN Ic, albeit lacking the usual Oifeature. Its light curve is similar to the typical SN Ic with decline rates (ΔM15,V= 0.84) and absolute magnitudeMV= −18.35. However, after maximum light, this SN has unusual spectroscopic features, a large degree of line blending, significant line blanketing in the blue (λ< 5000 Å), and strong Caiiabsorption features during and after peak brightness. These unusual spectral features are similar to models of subluminous thermonuclear explosions, specifically double-detonation models of SNe Ia. Photometrically, SN 2019eix appears to be somewhat brighter with slower decline rates than other double-detonation candidates. We modeled the spectra using the radiative-transfer codeTARDISusing SN 1994I (an SN Ic) as a base model to see whether we could reproduce the unusual features of SN 2019eix and found them to be consistent with the exception of the Oifeature. We also compared SN 2019eix with double-detonation models and found them to best match the observations of SN 2019eix, but failed to reproduce its full photometric and spectroscopic evolution.
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SN 2019ewu: A Peculiar Supernova with Early Strong Carbon and Weak Oxygen Features from a New Sample of Young SN Ic Spectra
Abstract With the advent of high-cadence, all-sky automated surveys, supernovae (SNe) are now discovered closer than ever to their dates of explosion. However, young premaximum light follow-up spectra of Type Ic SNe (SNe Ic), probably arising from the most-stripped massive stars, remain rare despite their importance. In this Letter, we present a set of 49 optical spectra observed with the Las Cumbres Observatory through the Global Supernova Project for 6 SNe Ic, including a total of 17 premaximum spectra, of which 8 are observed more than a week beforeV-band maximum light. This data set increases the total number of publicly available premaximum-light SN Ic spectra by 25%, and we provide publicly available SNID templates that will significantly aid in the fast identification of young SNe Ic in the future. We present a detailed analysis of these spectra, including Feii5169 velocity measurements, Oi7774 line strengths, and continuum shapes. We compare our results to published samples of stripped SNe in the literature and find one SN in our sample that stands out. SN 2019ewu has a unique combination of features for an SN Ic: an extremely blue continuum, high absorption velocities, a P Cygni–shaped feature almost 2 weeks before maximum light that TARDIS radiative transfer modeling attributes to Ciirather than Hα, and weak or nonexistent Oi7774 absorption feature until maximum light.
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- PAR ID:
- 10398379
- Publisher / Repository:
- DOI PREFIX: 10.3847
- Date Published:
- Journal Name:
- The Astrophysical Journal Letters
- Volume:
- 944
- Issue:
- 2
- ISSN:
- 2041-8205
- Format(s):
- Medium: X Size: Article No. L49
- Size(s):
- Article No. L49
- Sponsoring Org:
- National Science Foundation
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