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.


IPAC Authors

George Helou

IPAC Executive Director

Frank Masci

Senior Scientist

Ben Rusholme

Chief Engineer

Dave Shupe

Senior Scientist