GRB 090423 is Oldest and Most Distant Object Yet Discovered
Back on April 23 of this year, NASA’s Swift telescope detected a gama-ray burst (GRB), specifically documented as GRB 090423. About 20 minutes after the burst, one team led by UK astronomer Nial Tanvir began observations using the United Kingdom Infrared Telescope (UKIRT) on Mauna Kea, Hawaii. About 14 hours after the burst, another team led by Italian astronomer Ruben Salvaterra began their own observations using the Telescopio Nazionale Galileo (TNG) on La Palma, in the Canary Islands. The both teams were able to observe the afterglow for 10 days.
A GRB is the most powerful explosion since the Big Bang. GRBs occur somewhere in our sky approximately once per day and are brief, but intense, flashes of gamma radiation. They last from a few milliseconds to a few hundred seconds. GRBs are thought to be associated with the cataclysmic death of a massive star, and are thought to be triggered by the center of the star collapsing to form a black hole.
The two teams have reported the results of their careful study of GRB 090423. Their results indicate that the star that collapsed was 13.1 billion light-years away. The distance suggests that the star collapsed roughly 625 million years after the Big Bang. This is the oldest and most distant celestial object in the known universe. If the two teams’ results are correct it would suggest that massive stars were being born and dying as early as about 625 million years after the Big Bang.
Follow-up studies are planned for next year. Astronomers will use the Hubble Space Telescope to try to locate the distant and early galaxy from which the GRB came. For more information on this event, and for more information on the referenced observatories, check out these links:
Bursting at High Redshift. Editor’s Summary. October 29, 2009, Nature.com.
Stellar Blas is Record-Breaker. Victoria Gill. October 28, 2009. BBC News.
NASA’s Swift Gama-Ray Burst Mission Home Page
United Kingdom Infra-Red Telescope (UKIRT)
Telescopio Nazionale Galileo (TNG)