The Type II-plateau Supernova 2017eaw in NGC 6946 and Its Red Supergiant Progenitor

• Published in: The Astrophysical journal Vol. 875; no. 2; pp. 136 - 158
• Main Authors: Van Dyk, Schuyler D., Zheng, WeiKang, Maund, Justyn R., Brink, Thomas G., Srinivasan, Sundar, Andrews, Jennifer E., Smith, Nathan, Leonard, Douglas C., Morozova, Viktoriya, Filippenko, Alexei V., Conner, Brody, Milisavljevic, Dan, de Jaeger, Thomas, Long, Knox S., Isaacson, Howard, Crossfield, Ian J. M., Kosiarek, Molly R., Howard, Andrew W., Fox, Ori D., Kelly, Patrick L., Piro, Anthony L., Littlefair, Stuart P., Dhillon, Vik S., Wilson, Richard, Butterley, Timothy, Yunus, Sameen, Channa, Sanyum, Jeffers, Benjamin T., Falcon, Edward, Ross, Timothy W., Hestenes, Julia C., Stegman, Samantha M., Zhang, Keto, Kumar, Sahana
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 20.04.2019; IOP Publishing
• Subjects: Astrophysics; galaxies: distances and redshifts; galaxies: individual (NGC 6946); Hubble Space Telescope; Metallicity; Photosphere; Red giant stars; Space telescopes; Spectral energy distribution; stars: massive; Supergiant stars; supergiants; Supernova; supernovae: general; supernovae: individual (SN 2017eaw)
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ab1136

We present extensive optical photometric and spectroscopic observations, from 4 to 482 days after explosion, of the Type II-plateau (II-P) supernova (SN) 2017eaw in NGC 6946. SN 2017eaw is a normal SN II-P intermediate in properties between, for example, SN 1999em and SN 2012aw and the more luminous SN 2004et, also in NGC 6946. We have determined that the extinction to SN 2017eaw is primarily due to the Galactic foreground and that the SN site metallicity is likely subsolar. We have also independently confirmed a tip-of-the-red-giant-branch (TRGB) distance to NGC 6946 of 7.73 0.78 Mpc. The distances to the SN that we have also estimated via both the standardized candle method and expanding photosphere method corroborate the TRGB distance. We confirm the SN progenitor identity in pre-explosion archival Hubble Space Telescope (HST) and Spitzer Space Telescope images, via imaging of the SN through our HST Target of Opportunity program. Detailed modeling of the progenitor's spectral energy distribution indicates that the star was a dusty, luminous red supergiant consistent with an initial mass of ∼15 M .