Astronomy Picture of the Day—20190114

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2019January 14

ycho'sSupernova Remnant in X-ray

ImageCredit: NASA / CXC / F.J. Lu (Chinese Academy of Sciences) et al.

Explanation:What star created this huge puffball? What's pictured is the hot expandingnebula of Tycho's supernova remnant, the result of a stellar explosion firstrecorded over 400 years ago by the famous astronomer Tycho Brahe. The featuredimage is a composite of three X-ray colors taken by the orbiting Chandra X-rayObservatory. The expanding gas cloud is extremely hot, while slightly differentexpansion speeds have given the cloud a puffy appearance. Although the starthat created SN 1572, is likely completely gone, a star dubbed Tycho G, too dimto be discerned here, is thought to be a companion. Finding progenitor remnantsof Tycho's supernova is particularly important because the supernova is of TypeIa, an important rung in the distance ladder that calibrates the scale of thevisible universe. The peak brightness of Type Ia supernovas is thought to bewell understood, making them quite valuable in exploring the relationshipbetween faintness and farness in the distant universe.