Black Hole May
Have Ripped Star Apart Causing Unprecedented
ScienceDaily (Apr. 7, 2011)
— NASA's Swift, Hubble Space Telescope and
Chandra X-ray Observatory have teamed up to study
the most puzzling cosmic blasts yet observed.
More than a week later, high-energy radiation
continues to brighten and fade from its location.
Astronomers say they have never seen anything this
bright, long-lasting and variable before.
Usually, gamma-ray bursts mark the destruction of
a massive star, but flaring emission from these
events never lasts more than a few hours.
research is ongoing, astronomers say that the
unusual blast likely arose when a star wandered
too close to its galaxy's central black hole.
Intense tidal forces tore the star apart, and the
infalling gas continues to stream toward the hole.
According to this model, the spinning black hole
formed an outflowing jet along its rotational
axis. A powerful blast of X- and gamma rays is
seen if this jet is pointed in our direction.
28, Swift's Burst Alert Telescope discovered the
source in the constellation Draco when it erupted
with the first in a series of powerful X-ray
blasts. The satellite determined a position for
the explosion, now cataloged as gamma-ray burst
(GRB) 110328A, and informed astronomers
As dozens of telescopes turned to study the spot,
astronomers quickly noticed that a small, distant
galaxy appeared very near the Swift position. A
deep image taken by Hubble on April 4 pinpoints
the source of the explosion at the center of this
galaxy, which lies 3.8 billion light-years away.
day, astronomers used NASA's Chandra X-ray
Observatory to make a four-hour-long exposure of
the puzzling source. The image, which
locates the object 10 times more precisely than
Swift can, shows that it lies at the center of the
galaxy Hubble imaged.
of objects in our own galaxy that can produce
repeated bursts, but they are thousands to
millions of times less powerful than the
bursts we are seeing now. This is truly
extraordinary," said Andrew Fruchter at the Space
Telescope Science Institute in Baltimore.
"We have been eagerly awaiting the Hubble
observation," said Neil Gehrels, the lead
scientist for Swift at NASA's Goddard Space Flight
Center in Greenbelt, Md. "The fact that the
explosion occurred in the center of a galaxy tells
us it is most likely associated with a massive
black hole. This solves a key question about the
Most galaxies, including our own, contain central
black holes with millions of times the sun's mass;
those in the largest galaxies can be a thousand
times larger. The disrupted star probably
succumbed to a black hole less massive than the
Milky Way's, which has a mass four million times
that of our sun
Astronomers previously have detected stars
disrupted by supermassive black holes, but none
have shown the X-ray brightness and variability
seen in GRB 110328A. The source has
repeatedly flared. Since April 3, for example, it
has brightened by more than five times.
think that the X-rays may be coming from matter
moving near the speed of light in a particle jet
that forms as the star's gas falls toward the
explanation at the moment is that we happen to be
looking down the barrel of this jet," said
Andrew Levan at the University of Warwick in the
United Kingdom, who led the Chandra observations.
"When we look straight down these jets, a
brightness boost lets us view details we might
brightness increase, which is called relativistic
beaming, occurs when matter moving close to the
speed of light is viewed nearly head on.
Astronomers plan additional Hubble observations to
see if the galaxy's core changes brightness.