Astronomers searching for asteroids headed toward Earth have stumbled upon a harmless but fascinating discovery -- an exploding star, also known as a supernova.
The supernova, named 1999am, is located in a galaxy about 650 million light-years away. (A light-year is the distance light travels in one year, about 9.5 trillion kilometers or 6 trillion miles.) The star was unknown to astronomers until it was captured by the camera on NASA's Near Earth Asteroid Tracking (NEAT) system on February 18. The NEAT images show the star as it looked just a few weeks after the ancient explosion took place.
"We were fishing for salmon, and instead we caught a whale," said Dr. Steven Pravdo, project manager and co-investigator for NEAT. "The project is designed to look for asteroids and other objects that might pose a potential hazard to Earth. This supernova discovery is an added bonus for astronomers in general."
Supernova 1999am is a "Type Ia supernova," which means that before it exploded, it was a white dwarf star in orbit with a companion star. Near the end of its life, the white dwarf captured so much material from its companion that it became too massive to support itself, and exploded with as much energy as 100 billion suns. The supernova is now nearly as bright as the galaxy surrounding it, which is known as CGCG 060-009.
NEAT, with asteroid hunter Eleanor Helin as principal investigator, has been in operation since December 1995. It uses a large, sensitive and fully automated charge- coupled device (CCD) camera mounted on a 1-meter-diameter (39-inch) telescope. The telescope is operated by the U.S. Air Force atop Mt. Haleakela on the island of Maui, HI.
Since the middle of 1998, NEAT scientists have posted their data on a web site through a program called SkyMorph, a collaboration between JPL and NASA's Goddard Space Flight Center, Greenbelt, MD. While the NEAT project detects Earth-approaching objects by looking for celestial bodies that move over a period of time, the data can be used also to hunt for stationary objects that become brighter or dimmer over time. Thus, the images present a smorgasbord of astronomical options -- NEAT scientists pick out asteroids, while other astronomers select various cosmic morsels through the public SkyMorph web site.
"Through SkyMorph, astronomers may find an array of interesting objects, including supernovae," said Pravdo, principal investigator for SkyMorph. "In this case, we sent our data directly to the Lawrence Berkeley National Laboratory in Berkeley, California. Dr. Greg Aldering and other scientists with their Supernova Cosmology Project immediately found 1999am."
Pravdo said the Lawrence Berkeley National Laboratory scientists found the supernova by comparing images taken in February with previous NEAT data. They could clearly see a change in brightness, indicating the star had exploded and become a supernova. They further confirmed their finding with additional observations by ground-based telescopes. February 18 marked the first time NEAT scientists forwarded new data directly to the Berkeley lab, and as Pravdo pointed out, "We struck paydirt."
For information and an image of 1999am, go to the following web site: http://huey.jpl.nasa.gov/~spravdo/snanima.htm.
For more information on the NEAT project, go to http://huey.jpl.nasa.gov/~spravdo/neat.html.
Information on SkyMorph is available at http://skys.gsfc.nasa.gov/skymorph/skymorph.html.
Dr. Thomas McGlynn is lead scientist for SkyMorph at Goddard. The NEAT and SkyMorph projects are managed by JPL for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
For more information, go to http://www.jpl.nasa.gov. JPL is a division of the California Institute of Technology, Pasadena, CA.
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