Tycho Brahe's 1572 supernova as a standard type Ia explosion revealed from its light echo spectrum - AstrophysicsReport as inadecuate




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Abstract: Type Ia supernovae SNe Ia are thermonuclear explosions of white dwarf starsin close binary systems. They play an important role as cosmological distanceindicators and have led to the discovery of the accelerated expansion of theUniverse. Among the most important unsolved questions are how the explosionactually proceeds and whether accretion occurs from a companion or via themerging of two white dwarfs. Tycho Brahe-s supernova of 1572 SN 1572 isthought to be one of the best candidates for a SN Ia in the Milky Way. Theproximity of the SN 1572 remnant has allowed detailed studies, such as thepossible identification of the binary companion, and provides a uniqueopportunity to test theories of the explosion mechanism and the nature of theprogenitor. The determination of the yet unknown exact spectroscopic type of SN1572 is crucial to relate these results to the diverse population of SNe Ia.Here we report an optical spectrum of Tycho Brahe-s supernova near maximumbrightness, obtained from a scattered-light echo more than four centuries afterthe direct light of the explosion swept past Earth. We find that SN 1572belongs to the majority class of normal SNe Ia. The presence of a strong Ca IIIR feature at velocities exceeding 20,000 km-s, which is similar to thepreviously observed polarized features in other SNe Ia, suggests asphericity inSN 1572.



Author: Oliver Krause, Masaomi Tanaka, Tomonori Usuda, Takashi Hattori, Miwa Goto, Stephan Birkmann, Ken'ichi Nomoto

Source: https://arxiv.org/







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