Astronomers discover light echo from supernova | News | Notre Dame News | University of Notre Dame Skip To Content Skip To Navigation Skip To Search University of Notre Dame Notre Dame News Experts ND in the News Subscribe About Us Home Contact Search Menu Home › News › Astronomers discover light echo from supernova Astronomers discover light echo from supernova Published: June 04, 2013 Author: Marissa Gebhard An image of the NGC 1015 galaxy that hosted supernova 2009ig Astronomers have discovered light echoing off material surrounding a recent supernova explosion, SN 2009ig. The dust and gas that are reflecting the light are so close to the eruption center that it is likely related to the progenitor star. This discovery supports the theory that exploding white dwarfs become unstable from matter donated by large, non-degenerate stars. The light echo seen from SN 2009ig is only the sixth discovered from a type Ia supernova, and it is the most luminous of the echoes. An echo on Earth results when a loud sound is heard directly and again after being reflected by a wall to the listener. Because of the longer path length taken by the redirected sound, it is heard slightly later than the original noise. A light echo works the same way. Direct rays from the flash of a supernova are received at the Earth while some rays are scattered by particles in the host galaxy and redirected to the Earth. As with sound echoes, the time delay and light echo amplitude depends strongly on the distance between the source and the reflecting surfaces. SN 2009ig was discovered less than a day after it exploded by the Lick Observatory Supernova Search. It was found in the “NGC 1015” galaxy at a distance of 127 million light-years in the constellation Cetus, the sea monster. SN 2009ig was the brightest supernova of 2009 and was well studied by amateur and professional astronomers around maximum brightness. Observations with the Large Binocular Telescope and the Kitt Peak 4-meter telescope began in 2010, after SN 2009ig had faded by a factor of 10,000 from its peak brightness. “We planned to study how radioactive elements generated in the explosion decay with time, but we were surprised to see the fading abruptly halt. This was not a supernova we expected to produce a light echo,” said Peter Garnavich, professor of physics at the University of Notre Dame who is the lead investigator of the project. SN 2009ig was classified as a normal type Ia event. Type Ia supernovae are thought to be thermonuclear detonations of remnant cores of stars known as white dwarfs. This type of supernova was used to discover that the expansion rate of the universe is accelerating, implying a mysterious dark energy dominates the content of the universe. Yet, the progenitors of type Ia explosions remain uncertain. “We have used these explosions as precise candles to measure cosmological distances. It would be great to know where they come from,” said Garnavich. There are two competing theories on how white dwarf stars become unstable and explode. The single degenerate scenario has a large star donate mass to the white dwarf until instability is reached. The double-degenerate model proposes that two white dwarfs combine to reach the instability limit. The dusty, messy neighborhood around SN 2009ig supports the single degenerate scenario. The discovery was announced today at the 222nd meeting of the American Astronomical Society held in Indianapolis, Indiana, with coauthors Garnavich, Peter Milne (University of Arizona), Mark Leising (Clemson University) and Ginger Bryngelson (Francis Marion University). Contact: Peter Garnavich, professor of physics, 574-707-2528, pgarnavi@nd.edu Posted In: Research Home Experts ND in the News Subscribe About Us Related October 05, 2022 Astrophysicists find evidence for the presence of the first stars October 04, 2022 NIH awards $4 million grant to psychologists researching suicide prevention September 29, 2022 Notre Dame, Ukrainian Catholic University launch three new research grants September 27, 2022 Notre Dame, Trinity College Dublin engineers join to advance novel treatment for cystic fibrosis September 22, 2022 Climate-prepared countries are losing ground, latest ND-GAIN index shows For the Media Contact Office of Public Affairs and Communications Notre Dame News 500 Grace Hall Notre Dame, IN 46556 USA Facebook Twitter Instagram YouTube Pinterest © 2022 University of Notre Dame Search Mobile App News Events Visit Accessibility Facebook Twitter Instagram YouTube LinkedIn