A Bright Ultraviolet Excess in the Transitional 02es-like Type Ia Supernova 2019yvq

J. Burke, D. A. Howell, S. K. Sarbadhicary, D. J. Sand, R. C. Amaro, D. Hiramatsu, C. McCully, C. Pellegrino, J. E. Andrews, P. J. Brown, Koichi Itagaki, M. Shahbandeh, K. A. Bostroem, L. Chomiuk, E. Y. Hsiao, Nathan Smith, S. Valenti

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


We present photometric and spectroscopic observations of the nearby Type Ia SN 2019yvq, from its discovery ∼1 day after explosion to ∼100 days after its peak brightness. This SN exhibits several unusual features, most notably an extremely bright UV excess seen within ∼5 days of its explosion. As seen in Swift UV data, this early excess outshines its "peak"brightness, making this object more extreme than other supernovae (SNe) with early UV/blue excesses (e.g., iPTF14atg and SN 2017cbv). In addition, it was underluminous M B = -18.4, relatively quickly declining (Δm 15(B) = 1.37), and shows red colors past its early blue bump. Unusual (although not unprecedented) spectral features include extremely broad-lined and high-velocity Si absorption. Despite obvious differences in peak spectra, we classify SN 2019yvq as a transitional member of the 02es-like subclass due to its similarities in several respects (e.g., color, peak luminosity, peak Ti, and nebular [Ca ii]). We model this data set with a variety of published models, including SN ejecta-companion shock interaction and sub-Chandrasekhar-mass white dwarf (WD) double-detonation models. Radio constraints from the VLA place an upper limit of (4.5-20) 10-8 M o˙ yr-1 on the mass-loss rate from a symbiotic progenitor, which does not exclude a red giant or main-sequence companion. Ultimately, we find that no one model can accurately replicate all aspects of the data set, and further we find that the ubiquity of early excesses in 02es-like SNe Ia requires a progenitor system that is capable of producing isotropic UV flux, ruling out some models for this class of objects.

Original languageEnglish (US)
Article number142
JournalAstrophysical Journal
Issue number2
StatePublished - Oct 1 2021

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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