NASA's Hubble Space Telescope has returned valuable new images of supernova 1994I in the inner regions of the "Whirlpool Galaxy," M51, located 20 million light-years away in the constellation Canes Venatici. The images were taken with the Wide Field and Planetary Camera 2 (WFPC2).
The supernova was discovered by amateur astronomers on April 2, 1994 and has been the target of investigations by astronomers using ground-based optical and radio telescopes. At its brightest, around April 10, the supernova was about 100 million times brighter than the Sun.
Previous observations show that SN 1994I is a very unusual supernova, called "Type Ic," for which very few examples have been studied carefully.
Following initial observations with the International Ultraviolet Explorer satellite, which demonstrated that the supernova could be detected in the ultraviolet, a preplanned series of observations was initiated by the international SINS (Supernova Intensive Survey) team, headed by Dr. Robert P. Kirshner of Harvard-Smithsonian Center for Astrophysics.
The SINS group is using HST to study supernovae in the ultraviolet shortly after they are discovered, and at optical wavelengths as they become too faint to monitor from the ground. They hope to learn which stars explode as supernovae, what chemical elements are ejected by the eruption, and how to use these bright events as yardsticks for measuring the size of the universe.
For example, the Supernova 1987A, located in the nearby Large Magellanic Cloud, has been studied by the SINS team since the launch of the HST in 1990 and will continue to be a target of investigations.
A supernova is a violent stellar explosion that destroys a star, while ejecting the products of nuclear burning into the gas between stars.
Hubble Space Telescope has the unique capability of being able to image and to measure the spectra of distant supernovae in ultraviolet light. As the M51 supernova ages, Hubble will see more deeply into the interior of the exploded star. This will allow astronomers to probe the chemical composition of the debris and to learn more about the type of star that exploded. Debris from supernova explosions play a central role in increasing the heavy element abundance of galaxies. The material that makes up the Sun, the Earth, and our bodies was once inside stars that exploded long before the solar system formed about five billion years ago.
Ray Villard, STScI
Dr. Robert P. Kirshner, Harvard University