A Glimpse Back 7.5 Billion Years
March 19, 2008: Gamma-Ray Burst 080319B
GRB 080319B was a remarkable gamma-ray burst (GRB) detected by the Swift satellite at 06:12 UTC on March 19, 2008. The burst set a new record for the farthest object that could have been seen with the naked eye. It had a peak visual apparent magnitude of 5.8 and remained visible to human eyes for approximately 30 seconds. The magnitude was brighter than 9.0 for some 60 seconds. [artist’s depiction above]
Scientists believe GRB 080319B would have been visible to the naked eye for about 40 seconds if anyone had been looking its way, toward the constellation Bootes.
This is all the more remarkable given that it exploded an estimated 7.4 billion years ago—before the sun and Earth had formed. It took the light that long to reach earth. This is roughly half the time since the Big Bang. Essentially a time in the universe when the stars were formed.
The afterglow of the burst set a new record for the “most intrinsically bright object ever observed by humans in the universe”, 2.5 million times brighter than the brightest supernova to date (SN 2005ap).
Until this gamma-ray burst event, the Triangulum Galaxy, at a distance of about 2.9 million light years, was the most distant object visible to the naked eye. The galaxy remains the most distant permanent object viewable without aid.
It was soon suggested that this spectacle be named the Clarke Event, as it first reached Earth just hours before the death of Arthur C. Clarke, who was the 1956 Hugo Award winner for his 1955 science fiction short story “The Star”.
TheStar [Click then click to read full text]
Gamma-ray bursts (GRBs) are flashes of gamma rays associated with extremely energetic explosions that have been observed in distant galaxies. They are the brightest electromagnetic events known to occur in the universe. Bursts can last from ten milliseconds to several minutes. The initial burst is usually followed by a longer-lived “afterglow” emitted at longer wavelengths (X-ray, ultraviolet, optical, infrared, microwave and radio).
Drawing of a massive star collapsing to form a black hole. Energy released as jets along the axis of rotation forms a gamma ray burst that lasts from a few milliseconds to minutes. Such an event within several thousand light years of Earth could disrupt the biosphere by wiping out half of the ozone layer, creating nitrogen dioxide and potentially cause a mass extinction.
Most observed GRBs are believed to consist of a narrow beam of intense radiation released during a supernova or hyper nova as a rapidly rotating, high-mass star collapses to form a neutron star, quark star, or black hole.
The sources of most GRBs are billions of light years away from Earth, implying that the explosions are both extremely energetic (a typical burst releases as much energy in a few seconds as the Sun will in its entire 10-billion-year lifetime) and extremely rare (a few per galaxy per million years. All observed GRBs have originated from outside the Milky Way galaxy.