SN 2008S: A cool super-eddington wind in a supernova impostor

Nathan Smith, Mohan Ganeshalingam, Ryan Chornock, Alexei V. Filippenko, Weidong Li, Jeffrey M. Silverman, Thea N. Steele, Christopher V. Griffith, Niels Joubert, Nicholas Y. Lee, Thomas B. Lowe, Martin P. Mobberley, Dustin M. Winslow

Research output: Contribution to journalArticle

82 Citations (Scopus)

Abstract

We present visual-wavelength photometry and spectroscopy of supernova (SN) 2008S. Based on the low peak luminosity for a SN of MR = -13.9 mag, photometric and spectral evolution unlike that of low-luminosity SNe, a late-time decline rate slower than 56Co decay, and slow outflow speeds of 600-1000 km s-1, we conclude that SN 2008S is not a true core-collapse SN and is probably not an electron-capture SN. Instead, we show that SN 2008S more closely resembles an "SN impostor" event like SN 1997bs, analogous to the giant eruptions of luminous blue variables (LBVs). Its total radiated energy was 1047.8 erg, and it may have ejected 0.05-0.2 M in the event. We discover an uncanny similarity between the spectrum of SN 2008S and that of the Galactic hypergiant IRC+10420, which is dominated by narrow Hα, [Ca II], and Ca II emission lines formed in an opaque wind. We propose a scenario where the vastly super-Eddington (Γ 40) wind of SN 2008S partly fails because of reduced opacity due to recombination, as suggested for IRC+10420. The range of initial masses susceptible to eruptive LBV-like mass loss was known to extend down to 20-25 M, but estimates for the progenitor of SN 2008S (and the similar NGC 300 transient) may extend this range to ≲15 M. As such, SN 2008S may have implications for the progenitor of SN 1987A.

Original languageEnglish (US)
JournalAstrophysical Journal
Volume697
Issue number1 PART 2
DOIs
StatePublished - 2009
Externally publishedYes

Fingerprint

supernovae
erg
recombination
outflow
volcanic eruption
spectroscopy
wavelength
electron
energy
luminosity
supernova 1987A
opacity
electron capture
volcanic eruptions
photometry
speed
loss
rate
decay

Keywords

  • Stars: mass loss
  • Supernovae: individual (SN 2008S)

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Smith, N., Ganeshalingam, M., Chornock, R., Filippenko, A. V., Li, W., Silverman, J. M., ... Winslow, D. M. (2009). SN 2008S: A cool super-eddington wind in a supernova impostor. Astrophysical Journal, 697(1 PART 2). https://doi.org/10.1088/0004-637X/697/1/L49

SN 2008S : A cool super-eddington wind in a supernova impostor. / Smith, Nathan; Ganeshalingam, Mohan; Chornock, Ryan; Filippenko, Alexei V.; Li, Weidong; Silverman, Jeffrey M.; Steele, Thea N.; Griffith, Christopher V.; Joubert, Niels; Lee, Nicholas Y.; Lowe, Thomas B.; Mobberley, Martin P.; Winslow, Dustin M.

In: Astrophysical Journal, Vol. 697, No. 1 PART 2, 2009.

Research output: Contribution to journalArticle

Smith, N, Ganeshalingam, M, Chornock, R, Filippenko, AV, Li, W, Silverman, JM, Steele, TN, Griffith, CV, Joubert, N, Lee, NY, Lowe, TB, Mobberley, MP & Winslow, DM 2009, 'SN 2008S: A cool super-eddington wind in a supernova impostor', Astrophysical Journal, vol. 697, no. 1 PART 2. https://doi.org/10.1088/0004-637X/697/1/L49
Smith N, Ganeshalingam M, Chornock R, Filippenko AV, Li W, Silverman JM et al. SN 2008S: A cool super-eddington wind in a supernova impostor. Astrophysical Journal. 2009;697(1 PART 2). https://doi.org/10.1088/0004-637X/697/1/L49
Smith, Nathan ; Ganeshalingam, Mohan ; Chornock, Ryan ; Filippenko, Alexei V. ; Li, Weidong ; Silverman, Jeffrey M. ; Steele, Thea N. ; Griffith, Christopher V. ; Joubert, Niels ; Lee, Nicholas Y. ; Lowe, Thomas B. ; Mobberley, Martin P. ; Winslow, Dustin M. / SN 2008S : A cool super-eddington wind in a supernova impostor. In: Astrophysical Journal. 2009 ; Vol. 697, No. 1 PART 2.
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