Topic: Mid May astrtonomy bulletin

[Clive]

ICE FOUND ON ASTEROID
NASA

Scientists have detected water-ice and carbon-containing compounds on
the surface of an asteroid.  A seemingly sweeping generalisation from
the discovery of those substances on *one* large asteroid has resulted
in a suggestion that some asteroids, along with comets, were the water
carriers for the primordial Earth.  The discovery is a result of seven
observations, the first of which was made in 2002, of asteroid 24
Themis by astronomers who were using an infrared telescope.  The
findings are surprising because it was believed that Themis, orbiting
at 479 million kilometres, was too close to the Sun to carry ice left
over from the Solar System's origin 4.6 billion years ago.


GALACTIC STAR FORMATION IS SLOWING
ESA

Astronomers using the Herschel infrared telescope have shown that the
formation of new stars in galaxies like the Milky Way has declined
fivefold in the last three billion years.  Observing in the infrared
has allowed scientists to see galaxies, mainly spiral ones like the
Milky Way, that were previously hidden from view by cosmic dust
clouds.  The Herschel telescope, launched a year ago to study star
formation, is the biggest ever sent into space, and is orbiting at a
distance of 1.5 million kilometres from the Earth.


BLACK HOLE THROWN OUT OF GALAXY
RAS

Astronomers who have been comparing positional catalogues of X-ray
sources and of galaxies have found what appears to be a super-massive
black hole leaving its home galaxy at high speed.  The material that
falls into black holes heats up dramatically on its final journey and
often causes black holes to be strong X-ray sources.  X-rays are also
able to penetrate the dust and gas that obscures the centre of a
galaxy, giving astronomers a clear view of the region around the black
hole, with the bright source appearing as a starlike point.  Looking
at one galaxy in the catalogue, researchers noticed that the point of
light was offset from the centre and yet was so bright that it could
well be associated with a super-massive black hole.  The black hole
appears to be in the process of being expelled from its galaxy at high
speed.  Since such objects can have masses equivalent to 1 billion
Suns, it takes a special set of conditions to cause that to happen.
It is being speculated that the newly-discovered object may have
resulted from the merger of two smaller black holes.  Models suggest
that the merged hole that results is shot out at a high speed, that
depends on the direction and speed at which the two black holes rotate
before their collision.


MOST DISTANT CLUSTER OF GALAXIES
IPMU, Japan

Galaxies seem not to be uniformly distributed in the Universe, but to
be arrayed in filamentary structures that form a gigantic cosmic
spider web.  Clusters of galaxies are often located at knots in the
filaments.  The most distant cluster known until now is about 9.2
billion light-years away.

The expansion of the universe shifts the light of distant objects
away from visible wavelengths, towards the infrared.  Observing in the
infrared may therefore enable astronomers to see more distant
objects.  On the other hand, clusters of galaxies tend to contain a lot
of matter heated to extreme temperatures, at which the emitted light
is of such short wavelengths that even despite the redshift it appears
as X-rays.

A team of astronomers from Japan and Germany has used an infrared
camera on the Japnese Subaru telescope in Hawaii to discover the most
distant cluster of galaxies observed up to the present, 9.6 billion
light-years away.  The team also used the orbiting X-ray observatory
XMM-Newton, and detected a clear signature of hot gas in the cluster.


ENGINEERS WORKING ON VOYAGER 2 DATA SYSTEM
ScienceDaily

Engineers have shifted the Voyager 2 spacecraft into a mode that
transmits only spacecraft health and status data while they try to
correct an unexpected change in the pattern of returning data.
Preliminary engineering data received on May 1 show that the
spacecraft is basically healthy, and that the trouble is with the
flight data system, which formats the data to send back to Earth.  The
first changes in the return of data packets from Voyager 2 appeared on
April 22.  Engineers got their first chance to send commands to the
spacecraft on April 30.  It takes nearly 13 hours for signals to reach
the spacecraft and the same for signals to come back to the Earth.

Voyager 2 was launched on 1977 August 20, about a fortnight before its
twin spacecraft, Voyager 1.  The two spacecraft are the most distant
man-made objects, out at the edge of the heliosphere, the bubble that
the Sun creates around the Solar System.  Voyager 2 is about 13.8
billion kilometres away, Voyager 1 about 16.9 billion kilometres.
Mission managers expect Voyager 1 to leave the Solar System and enter
interstellar space in the next five years or so, with Voyager 2 to
follow shortly after.  Voyager 1 is in good health and performing
normally.  Voyager 2's initial mission was a four-year journey to
Saturn, but as part of a mission extension it also flew past Uranus in
1986 and Neptune in 1989, taking advantage of a once-in-176-years
alignment to take a grand tour of the outer planets -- and it is still
returning data 33 years after launch.