SN 2017cfd: A Normal Type Ia Supernova Discovered Very Young

• Published in: arXiv.org
• Main Authors: Han, Xuhui, Zheng, WeiKang, Stahl, Benjamin E, Burke, Jamison, Vinko, Jozsef, de Jaeger, Thomas, Brink, Thomas G, Cseh, Borbala, Hiramatsu, Daichi, Howell, D Andrew, Ignacz, Bernadett, Konyves-Toth, Reka, Mate Krezinger, McCully, Curtis, Ordasi, Andras, Pinter, Dora, Sarneczky, Krisztian, Szakats, Robert, Tang, Kevin, Vida, Krisztian, Wang, Jing, Jianyan Wei, Wheeler, J Craig, Xin, Liping, Filippenko, Alexei V
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 18.11.2019
• Subjects: Biological evolution; Brightness; Color; Companion stars; Galaxies; Luminosity; Photometry; Physics - High Energy Astrophysical Phenomena; Physics - Solar and Stellar Astrophysics; Red shift; Supernovae
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1911.07734

The Type~Ia supernova (SN~Ia) 2017cfd in IC~0511 (redshift z = 0.01209+- 0.00016$) was discovered by the Lick Observatory Supernova Search 1.6+-0.7 d after the fitted first-light time (FFLT; 15.2 d before B-band maximum brightness). Photometric and spectroscopic follow-up observations show that SN~2017cfd is a typical, normal SN~Ia with a peak luminosity MB ~ -19.2+-0.2 mag, Delta m15(B) = 1.16 mag, and reached a B-band maximum ~16.8 d after the FFLT. We estimate there to be moderately strong host-galaxy extinction (A_V = 0.39 +- 0.03 mag) based on MLCS2k2 fitting. The spectrum reveals a Si~II lambda 6355 velocity of ~11,200 kms at peak brightness. The analysis shows that SN~2017cfd is a very typical, normal SN Ia in nearly every aspect. SN~2017cfd was discovered very young, with multiband data taken starting 2 d after the FFLT, making it a valuable complement to the currently small sample (fewer than a dozen) of SNe~Ia with color data at such early times. We find that its intrinsic early-time (B - V)0 color evolution belongs to the "blue" population rather than to the distinct "red" population. Using the photometry, we constrain the companion star radius to be < 2.5 R_sun, thus ruling out a red-giant companion.