Farthest Supernova Yet Discovered by NASA: Star Explosion Reveals Cosmic Distances
NASA's Hubble Space Telescope has located the farthest supernova to date of the type used to measure cosmic distances. The finding helps open new insights into how these ancient stars explode.
The newly discovered supernova, named UDS10Wil or SN Wilson for short, is in a special class of exploding stars known as Type Ia. This particular supernova exploded more than 10 billion years ago and possesses a consistent level of brightness than can be used to measure the expansion of space. It could also help reveal clues to the nature of dark energy, which is the mysterious force that accelerates the rate of expansion of the universe.
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"The Type Ia supernovae give us the most précis yardstick ever built, but we're still not quite sure if it always measures exactly a yard," said Steve Rodney, one of the researchers, in a press release. "The more we understand these supernovae, the more precise our cosmic yardstick will become."
The researchers found the supernova as part of a three-year Hubble program that first began in 2010. The initiative aimed to survey Type Ia supernovae and determined whether or not they've changed during the 13.8 billion years since the explosive birth of the universe. In particular, the researchers took advantage of near-infrared light to search for these supernovae and verified their distances with spectroscopy. Now, they've located the furthest one to date.
SN Wilson pushes roughly 350 million years farther back in time that the previous record holder, allowing researchers to better distinguish between two competing explosion models for Type Ia supernovae. The first of these models dictates that the explosion is caused by a merger between two white dwarfs. The other model, in contrast, says that a white dwarf feeds off of its normal, partner star and eventually explodes when it gathers too much mass.
In fact, the researchers found evidence of a sharp decline in the rate of Type Ia supernova blasts between 7.5 and 10 billion years ago. This evidence seems to point to the fact that the merger between two white dwarfs is the most likely theory, since it predicts that most stars in the universe are too young to become Type Ia supernovae.
So how is this relevant to future studies? Knowing the type of trigger for Type Ia supernovae will help show how quickly the universe enriched itself with heavier elements, such as iron. This, in turn, will allow researchers to understand how quickly planets formed, which utilize these raw materials.
The findings have been published in The Astrophysical Journal.