OPTICAL OBSERVATIONS OF THE TYPE IA SUPERNOVA SN 2011fe IN M101 FOR NEARLY 500 DAYS

• Published in: The Astrophysical journal Vol. 820; no. 1; p. 67
• Main Authors: Zhang, Kaicheng, Wang, Xiaofeng, Zhang, JuJia, Zhang, Tianmeng, Ganeshalingam, Mohan, Li, Weidong, Filippenko, Alexei V., Zhao, Xulin, Zheng, Weikang, Bai, Jinming, Chen, Jia, Chen, Juncheng, Huang, Fang, Mo, Jun, Rui, Liming, Song, Hao, Sai, Hanna, Li, Wenxiong, Wang, Lifan, Wu, Chao
• Format: Journal Article
• Language: English
• Published: United States The American Astronomical Society 20.03.2016
• Subjects: ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; Band spectra; CALCIUM; DIAGRAMS; Ejecta; ELEMENT ABUNDANCE; Emission; EMISSION SPECTRA; INDEXES; Light curve; LUMINOSITY; METALLICITY; OXYGEN; PHOTOMETRY; Photons; Spectra; SUPERNOVAE; supernovae: general; supernovae: individual (SN 2011fe); TRAPPING; TRIPLETS; ULTRAVIOLET RADIATION; VELOCITY; VISIBLE RADIATION; WHITE DWARF STARS
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/0004-637X/820/1/67

ABSTRACT We present well-sampled optical observations of the bright Type Ia supernova (SN Ia) SN 2011fe in M101. Our data, starting from ∼16 days before maximum light and extending to ∼463 days after maximum, provide an unprecedented time series of spectra and photometry for a normal SN Ia. Fitting the early-time rising light curve, we find that the luminosity evolution of SN 2011fe follows a tn law, with the index n being close to 2.0 in the VRI bands but slightly larger in the U and B bands. Combining the published ultraviolet (UV) and near-infrared (NIR) photometry, we derive the contribution of UV/NIR emission relative to the optical. SN 2011fe is found to have stronger UV emission and reaches its UV peak a few days earlier than other SNe Ia with similar Δm15(B), suggestive of less trapping of high-energy photons in the ejecta. Moreover, the U-band light curve shows a notably faster decline at late phases (t 100-300 days), which also suggests that the ejecta may be relatively transparent to UV photons. These results favor the notion that SN 2011fe might have a progenitor system with relatively lower metallicity. On the other hand, the early-phase spectra exhibit prominent high-velocity features (HVFs) of O i λ7773 and the Ca ii NIR triplet, but only barely detectable in Si ii 6355. This difference can be caused by either an ionization/temperature effect or an abundance enhancement scenario for the formation of HVFs; it suggests that the photospheric temperature of SN 2011fe is intrinsically low, perhaps owing to incomplete burning during the explosion of the white dwarf.