%AStritzinger, Maximilian%AShappee, Benjamin%APiro, Anthony%AAshall, Christopher%ABaron, E.%AHoeflich, Peter%AHolmbo, Simon%AHoloien, Thomas%APhillips, M.%ABurns, C.%AContreras, Carlos%AMorrell, Nidia%ATucker, Michael%BJournal Name: Astrophysical journal; Journal Volume: 861 %D2018%I %JJournal Name: Astrophysical journal; Journal Volume: 861 %K %MOSTI ID: 10093384 %PMedium: X %TRed versus Blue: Early Observations of Thermonuclear Supernovae Reveal Two Distinct Populations? %XWe examine the early phase intrinsic (B - V)0 color evolution of a dozen SNe Ia discovered within three days of the inferred time of first light (t first) and have (B - V)0 color information beginning within five days of t first. The sample indicates there are two distinct early populations. The first is a population exhibiting blue colors that slowly evolve, and the second population exhibits red colors and evolves more rapidly. We find that the early blue events are all 1991T/1999aa-like with more luminous, slower declining light curves than those exhibiting early red colors. Placing the first sample on the Branch diagram (i.e., ratio of Si II λλ5972, 6355 pseudo-Equivalent widths) indicates that all blue objects are of the Branch shallow silicon (SS) spectral type, while all early red events except for the 2000cx-like SN 2012fr are of the Branch Core Normal (CN) or CooL (CL) type. A number of potential processes contributing to the early emission are explored, and we find that, in general, the viewing-angle dependance inherent in the companion collision model is inconsistent with all of the SS objects with early-time observations being blue and exhibiting an excess. We caution that great care must be taken when interpreting early phase light curves as there may be a variety of physical processes that are possibly at play and significant theoretical work remains to be done. %0Journal Article