Abstract
We present pre-explosion photometry of the likely progenitor star of the Type II supernova (SN II) 2017eaw in NGC 6946. We use a Hubble Space Telescope (HST) image of SN 2017eaw to perform relative astrometry with HST and Spitzer Space Telescope (Spitzer) imaging, finding a single point source consistent with its position. We detect the progenitor star in > 40 epochs of HST and Spitzer imaging covering 12.9 yr to 43 d before discovery. While the progenitor luminosity was roughly constant for most of this period, there was a ~ 20 per cent increase in its 4.5 μ m luminosity over the final 3 yr before explosion. We interpret the bright mid-infrared emission as a signature of circumstellar dust around the progenitor system. Using the preexplosion photometry and assuming some circumstellar dust, we find the progenitor is most likely a red supergiant with log (L/L⊙) = 4.9 and T = 3350 K, obscured by a > 2 × 10-5 M⊙ dust shell with R = 4000R⊙ and T = 960 K. Comparing to single-star evolutionary tracks, we find that the progenitor star had an initial mass of 13M⊙ and a mass-loss rate of 2 × 10-7M⊙ yr-1, consistent with the population of SN II progenitor stars.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 2536-2547 |
| Number of pages | 12 |
| Journal | Monthly Notices of the Royal Astronomical Society |
| Volume | 481 |
| Issue number | 2 |
| DOIs | |
| State | Published - Dec 1 2018 |
Funding
We would like to thank Ori Fox, Nathan Smith, Stephen Smartt, and Scott Adams for helpful discussions. This work is supported by NSF grant AST-1518052, the Gordon & Betty Moore Foundation, the Heising-Simons Foundation, and by fellowships from the Alfred P. Sloan Foundation and the David and Lucile Packard Foundation to RJF. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. The Hubble Space Telescope (HST) is operated by NASA/ESA. The HST data used in this manuscript come from programs SNAP-9788, GO-14156, GO-14638, GO-14786, and SNAP- 15166 (PIs Ho, Leroy, Long, Williams, and Filippenko, respectively). Some of our analysis is based on data obtained from the HST archive operated by STScI. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. The Spitzer/IRAC data reported in this manuscript come from Program IDs 159 (PI Kennicutt), 3248 (PI Meikle), 10136 (PI Kasliwal), 11063 (PI Kasliwal), 13053 (PI Kasliwal), 13239 (PI Krafton), 20256 (PI Meikle), 20320 (PI Sugerman), 30494 (PI Sugerman), 40010 (PI Meixner), 60071 (PI Andrews), 70008 (PI Andrews), 80015 (PI Kochanek), 80131 (PI Andrews), and 90178 (PI Andrews). This work makes use of observations from the LCOGT network. Facilities: HST (ACS/WFC3), Spitzer (IRAC), LCO (FLOYDS). This work is supported by NSF grant AST-1518052, the Gordon & Betty Moore Foundation, the Heising–Simons Foundation, and by fellowships from the Alfred P. Sloan Foundation and the David and Lucile Packard Foundation to RJF.
Keywords
- Stars: evolution
- Stars: mass-loss
- Supernovae: general
- Supernovae: individual (SN 2017eaw)
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science