January 26, 2014

Nearby Type Ia Supernova Caught In The Act

[ Watch the Video: What Interstellar Blast Is Lighting Up The Sky? ]

redOrbit Staff & Wire Reports - Your Universe Online

Several NASA spacecraft and Earth-based observatories, including the Hubble Space Telescope and the Chandra X-ray Observatory, are studying an incredibly close supernova that took place on January 21, officials from the US space agency announced on Friday.

The stellar explosion, which has been designated SN 2014J, lies approximately 12 million light-years away in the galaxy M82, making it the nearest optical supernova in over 20 years. Furthermore, it could be the closest type Ia supernova (supernovae that occur in binary systems) to happen during the life of currently operating space missions.

The Swift Gamma-Ray Burst mission was the first spacecraft to get a look at the blast, as Swift's Ultraviolet/Optical Telescope (UVOT) captured the supernova and its host galaxy on January 22 – just one day after it took place. Astonishingly, SN 2014J is visible on images taken up to a week before its presence was discovered by Dr. Steve Fossey and students at the University of London Observatory.

“Finding and publicizing new supernova discoveries is often the weak link in obtaining rapid observations, but once we know about it, Swift frequently can observe a new object within hours,” Neil Gehrels, the mission's principal investigator at NASA's Goddard Space Flight Center in Maryland, said in a statement.

While the explosion is unusually close to the planet, the light from the supernova is being thinned by thick interstellar dust clouds in its host galaxy, which could reduce its apparent peak brightness. This dust scatters blue light, members of the Swift researcher team explained, which makes the UVOT see SN 2014J brightly in both visible and near-ultraviolent light, but very faintly in the mid-ultraviolet wavelengths.

However, this exceptionally close supernova will give astronomers an excellent chance to study how interstellar dust impacts its light. Type Ia supernovae tend to explode with unexpectedly similar intrinsic brightness, and according to NASA, this property makes them useful “standard candles” by which to explore the distant universe.

According to Dr. Peter Brown, a Texas A&M University astrophysicist who is heading up a team that is using Swift to obtain ultraviolet observations of supernovae, X-rays from a type Ia supernova have never been conclusively observed, so detection from Swift or another NASA craft would be significant.

“A type Ia supernova represents the total destruction of a white dwarf star by one of two possible scenarios,” NASA explained. “In one, the white dwarf orbits a normal star, pulls a stream of matter from it, and gains mass until it reaches a critical threshold and explodes. In the other, the blast arises when two white dwarfs in a binary system eventually spiral inward and collide.”

“Either way, the explosion produces a superheated shell of plasma that expands outward into space at tens of millions of miles an hour. Short-lived radioactive elements formed during the blast keep the shell hot as it expands,” the US space agency added. “The interplay between the shell's size, transparency and radioactive heating determines when the supernova reaches peak brightness.”

SN 2014J is expected to continue growing brighter into the first week of February, and by that time it could be visible using binoculars, NASA officials noted. M82, which is also known as the Cigar Galaxy, is located in the constellation Ursa Major and is a popular target for small telescopes. It is currently undergoing a powerful episode of star formation, which makes it several times brighter than the Milky Way.