
science & techESA/Hubble2002 · Eridanus constellation
A Hubble image reveals a white dwarf that survived its own supernova as a zombie star
NGC 1309 is a spiral galaxy about 100 million light-years away in the constellation Eridanus, shown in a Hubble Picture of the Week full of background galaxies. Its scientific interest lies in two supernovae. SN 2002fk was a textbook Type Ia explosion, the kind that happens when a white dwarf star blows apart. SN 2012Z was stranger: classified as a Type Iax event, its explosion did not destroy the white dwarf, which survived as a bright zombie star. Hubble images taken over several years also identified the white dwarf progenitor of a supernova before it exploded, a first.
Type Iax supernovae show that not every white dwarf explosion is the same, which matters for models of how these stars explode. Type Ia supernovae are central to measuring cosmic distances, so refining their physics affects cosmology. Spotting a progenitor before its explosion is a rare observational achievement.
Type Ia supernovae are used as standard candles to measure distances across the universe.
background
NGC 1309 is a spiral galaxy located approximately 120 million light-years away, appearing in the constellation Eridanus. It was discovered by German-British astronomer William Herschel on 3 October 1785.
NGC 1309 is about 75,000 light-years across, and is about 3/4s the width of the Milky Way. Its shape is classified as SA(s)bc, meaning that it has moderately wound spiral arms and no ring.
Bright blue areas of star formation can be seen in the spiral arms, while the yellowish central nucleus contains older-population stars. NGC 1309 is one of over 200 members of the Eridanus Group of galaxies.
From Wikipedia: NGC 1309 (CC BY-SA 4.0) ↗ESA/Hubble · CC BY 4.0
Image: ESA/Hubble & NASA, L. Galbany, S. Jha, K. Noll, A. Riess
