Submitted on September 9, 2009
Accepted on October 29, 2009
An Unusually Fast-Evolving Supernova
Dovi Poznanski 1*, Ryan Chornock 2, Peter E. Nugent 3, Joshua S. Bloom 2, Alexei V. Filippenko 2, Mohan Ganeshalingam 2, Douglas C. Leonard 4, Weidong Li 2, Rollin C. Thomas 3
1 Department of Astronomy, University of California, Berkeley, CA 94720–3411, USA.; Computational Cosmology Center, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA.
2 Department of Astronomy, University of California, Berkeley, CA 94720–3411, USA.
3 Computational Cosmology Center, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA.
4 Department of Astronomy, San Diego State University, Mail Code 1221, San Diego, CA 92182–1221, USA.
* To whom correspondence should be addressed.
Dovi Poznanski , E-mail: dovi{at}berkeley.edu
Analyses of supernovae (SNe) have revealed two main types of progenitors: exploding white dwarfs and collapsing massive stars. We present SN 2002bj, which stands out as different from any SN reported to date. Its light curve rises and declines very rapidly, yet reaches a peak intrinsic brightness greater than -18 mag. A spectrum obtained 7 days after discovery shows the presence of helium and intermediate-mass elements, yet no clear hydrogen or iron-peak elements. The spectrum only barely resembles that of a type Ia SN, with added carbon and helium. Its properties suggest that SN 2002bj may be representative of a class of progenitors that previously has been only hypothesized: a helium detonation on a white dwarf, ejecting a small envelope of material. New surveys should find many such objects, despite their scarcity.
