SN2019dge: A Helium-rich Ultra-stripped Envelope Supernova

September 2020 • 2020ApJ...900...46Y

Authors • Yao, Yuhan • De, Kishalay • Kasliwal, Mansi M. • Ho, Anna Y. Q. • Schulze, Steve • Li, Zhihui • Kulkarni, S. R. • Fruchter, Andrew • Rubin, David • Perley, Daniel A. • Fuller, Jim • Piro, Anthony L. • Fremling, C. • Bellm, Eric C. • Burruss, Rick • Duev, Dmitry A. • Feeney, Michael • Gal-Yam, Avishay • Golkhou, V. Zach • Graham, Matthew J. • Helou, George • Kupfer, Thomas • Laher, Russ R. • Masci, Frank J. • Miller, Adam A. • Rusholme, Ben • Shupe, David L. • Smith, Roger • Sollerman, Jesper • Soumagnac, Maayane T. • Zolkower, Jeffry

Abstract • We present observations of ZTF18abfcmjw (SN2019dge), a helium-rich supernova with a fast-evolving light curve indicating an extremely low ejecta mass (≈0.33 M_⊙) and low kinetic energy (≈1.3 × 10⁵⁰ erg). Early-time (<4 days after explosion) photometry reveals evidence of shock cooling from an extended helium-rich envelope of ∼0.1 M_⊙ located ∼1.2 × 10¹³ cm from the progenitor. Early-time He II line emission and subsequent spectra show signatures of interaction with helium-rich circumstellar material, which extends from ≳5 × 10¹³ cm to ≳2 × 10¹⁶ cm. We interpret SN2019dge as a helium-rich supernova from an ultra-stripped progenitor, which originates from a close binary system consisting of a mass-losing helium star and a low-mass main-sequence star or a compact object (i.e., a white dwarf, a neutron star, or a black hole). We infer that the local volumetric birth rate of 19dge-like ultra-stripped SNe is in the range of 1400-8200 $\,{\mathrm{Gpc}}^{-3}\,{\mathrm{yr}}^{-1}$ (i.e., 2%-12% of core-collapse supernova rate). This can be compared to the observed coalescence rate of compact neutron star binaries that are not formed by dynamical capture.

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IPAC Authors
(alphabetical)

George Helou

IPAC Executive Director

Frank Masci

Senior Scientist

Ben Rusholme

Chief Engineer

Dave Shupe

Senior Scientist