2018/02/20 by Thomas de Jaeger, T. de Jaeger, J. P. Anderson +16 · 49 citations
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Gamma-ray bursts and supernovae #Physics #Pulsars and Gravitational Waves Research #Supernova #Type (biology) #Type II supernova #astro-ph.HE
paper · pdf · doi:10.1093/mnras/sty508
published in Monthly Notices of the Royal Astronomical Society 476(4), 4592-4616 (Oxford University Press) · 27 pages, 94 figures, Accepted for publication in MNRAS
arxiv created 2018/02/20 · openalex publication_date 2018/02/23 · openalex created_date 2018/03/06 · arxiv updated 2018/03/14 · openalex updated_date 2026/08/06
We present a study of observed Type II supernova (SN II) colours using optical/near-infrared photometric data from the Carnegie Supernovae Project-I. We analyse four colours (B -V, ug, g -r, and g -Y ) and find that SN II colour curves can be described by two linear regimes during the photospheric phase. The first (s 1,colour ) is steeper and has a median duration of 40 days. The second, shallower slope (s 2,colour ) lasts until the end of the "plateau" ( 80 days). The two slopes correlate in the sense that steeper initial colour curves also imply steeper colour curves at later phases. As suggested by recent studies, SNe II form a continuous population of objects from the colour point of view as well. We investigate correlations between the observed colours and a range of photometric and spectroscopic parameters including the absolute magnitude, the V-band light-curve slopes, and metal-line strengths. We find that less luminous SNe II appear redder, a trend that we argue is not driven by uncorrected host-galaxy reddening. While there is significant dispersion, we find evidence that redder SNe II (mainly at early epochs) display stronger metal-line equivalent widths. Host-galaxy reddening does not appear to be a dominant parameter, neither driving observed trends nor dominating the dispersion in observed colours. Intrinsic SN II colours are most probably dominated by photospheric temperature differences, with progenitor metallicity possibly playing a minor role. Such temperature differences could be related to differences in progenitor radius, together with the presence or absence of circumstellar material close to the progenitor stars.