Astronomers capture spectacular images of supernova light echoing through space
Astrophysics researchers have released incredible new images that show an explosive gush of light as it reverberates through space for years after the star death that originally caused it.
Images of the phenomenon, known as a "light echo", were taken with NASA's Hubble Space Telescope as part of a collaboration including Dr Justyn Maund and PhD student Heloise Stevance from the University of Sheffield's Department of Physics and Astronomy.
A light echo occurs when light from a supernova – the explosion that occurs at the end of a star's life – scatters off interstellar dust clouds. The new Hubble images show the blast and its aftermath over a two-and-a-half year period and are the most detailed ever taken of a Type Ia supernova.
This is an exciting and rare phenomenon that allows us to map the gas and the dust that exists between stars in other galaxies.
Dr Justyn Maund
Senior Research Fellow
In the time-lapse animation assembled from the new images, the light echo can be seen as an an expanding shell of light from the explosion sweeping through interstellar space, like a ripple expanding on a pond. This movement illustrates that the space between stars is not a totally empty void.
Dr Justyn Maund said: "This is an exciting and rare phenomenon that allows us to map the gas and the dust that exists between stars in other galaxies. Only with the power of the Hubble Space Telescope have we been able to see this echo as it moves through the galaxy M82."
The scattered light from the stellar blast travels different distances to arrive at Earth. Some light comes to Earth directly from the supernova blast. Other light is delayed because it travels indirectly. In this case, the light is bouncing off a huge dust cloud that extends 300 to 1,600 light-years around the supernova and is being reflected toward Earth.
The stellar explosion, called SN 2014J, occurred in the nearby starburst galaxy M82, or Cigar galaxy, 11.4 million light-years away. So far, astronomers have spotted only 15 light echoes around supernovae outside our Milky Way galaxy, because they must be nearby for a telescope to capture them.
SN 2014J is classified as a Type Ia supernova and is the closest such blast in at least four decades. Therefore, the Hubble observations of the stellar blast's light echo are the most detailed images of a Type Ia supernova.
Stars of this kind explode in binary systems composed of a burned-out white dwarf star and a companion star. The companion spills material onto the white dwarf. Eventually, an explosion may be triggered when the white dwarf can no longer support the extra pressure of the accumulated matter. The details of this process are still the subject of ongoing research.
The supernova was discovered on 21 January 2014, and Hubble's Advanced Camera for Surveys took snaps until 28 April 2017.
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