APOD
Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
A Slow Explosion
Explanation: Why would a gamma ray burst fade so slowly? This behavior , recorded last October, is considered a new clue into the cause of gamma-ray bursts , the most powerful explosions known in the universe. The burst , first detected by the orbiting HETE satellite and later tracked by numerous ground-based telescopes, showed an unusually slow and tumultuous decay in visible light. Speculations on the cause of the unusual light curve include a blast wave striking a wind y circumburst medium, a blast wave energetically refreshed by a faster outgoing shock, and non-uniformity in a fast moving jet. Pictured above is the massive Wolf-Rayet star WR124, a star itself undergoing a slow explosion by producing a very powerful but tumultuous wind . Popular candidate progenitor sources for GRB s include supernova or hypernova explosions from massive stars, possibly ones with similarities to Wolf-Rayet stars .
| Date | March 25, 2003 |
|---|---|
| Credit | Credit: Y. Grosdidier ( U. Montreal ) et al., WFPC2 , HST , NASA |
| Authors & editors: | Robert Nemiroff (MTU) & Jerry Bonnell (UMCP) |
| A service of: |
ASD at NASA / GSFC, NASA Science Activation & Michigan Tech. U. |



