Light Echo From Supernova Seen By Hubble

The Hubble space telescope has patiently collected observations of supernova SN 2014J in the nearby M82 galaxy. The event was first observed on January 21, 2014, and the light emitted has been seen by the space observatory ricocheting off dust clouds, like waves in a pond.

The phenomenon was possible because the supernova lies behind a large quantity of interstellar material. The dust cloud that enshrines it is estimated to extend between 300 and 1,600 light-years around the object. This was extremely useful for astronomers after the object was discovered. They used its light to study in detail which elements were spread between the stars.

SN 2014J is located 11.4 million light-years away and its relative closeness was another advantage for these and many other observations (100 papers have discussed this object). Analyzing its emission, researchers confirmed that supernovae of this kind release a large amount of nickel when they explode.

Gif of the light echo. NASA/ESA/ Y. Yang (Texas A&M / Weizmann Institute of Science)

The discovery was serendipitous and occurred during an undergraduate training lesson at the University of London Observatory. SN 2014J is a popular target for amateur astronomers. In the sky, M82, also known as the Cigar Galaxy, is located near the Big Dipper.

The event is also of cosmological importance. SN 2014J is a type Ia supernova, explosions that always have (we think) the same luminosity. This fact allows researchers to use them as standard candles, cosmological milestones to measure the distance of faraway galaxies.

Type Ia supernovae happen when a white dwarf explodes after having stolen material from a companion star, either another white dwarf or an evolved star like a red giant. Astronomers looked at archival images of the object hoping to work out the nature of the companion but they couldn’t find any conclusive evidence.

Astronomers have spotted about 15 light echoes from supernovae outside our own galaxy. These are not easy to catch as they need to be relatively nearby for our telescopes to spot them.