|Diamond star thrills
By Dr David Whitehouse
BBC News Online
Twinkling in the sky
is a diamond star of 10 billion trillion trillion
carats, astronomers have discovered.
The cosmic diamond is a chunk
of crystallised carbon, 1,500 km across, some 50
light-years from the Earth in the constellation
It's the compressed heart of an
old star that was once bright like our Sun but
has since faded and shrunk.
Astronomers have decided to
call the star "Lucy," after the Beatles
song, "Lucy in the Sky with Diamonds."
Lucy in the sky
"You would need a
jeweller's loupe the size of the Sun to grade
this diamond!" says astronomer Travis
Metcalfe of the Harvard-Smithsonian Center for
Astrophysics, who led the team of researchers
that discovered it.
The diamond star completely
outclasses the largest diamond on Earth, the
530-carat Star of Africa which resides in the
Crown Jewels of England. The Star of Africa was
cut from the largest diamond ever found on Earth,
a measly 3,100-carat gem.
The huge cosmic diamond -
technically known as BPM 37093 - is actually a
crystallised white dwarf. A white dwarf is the
hot core of a star, left over after the star uses
up its nuclear fuel and dies. It is made mostly
For more than four decades,
astronomers have thought that the interiors of
white dwarfs crystallised, but obtaining direct
evidence became possible only recently.
The white dwarf is not only
radiant but also rings like a gigantic gong,
undergoing constant pulsations.
"By measuring those
pulsations, we were able to study the hidden
interior of the white dwarf, just like
seismograph measurements of earthquakes allow
geologists to study the interior of the Earth.
We figured out that the carbon
interior of this white dwarf has solidified to
form the galaxy's largest diamond," says
Astronomers expect our Sun will
become a white dwarf when it dies 5 billion years
from now. Some two billion years after that, the
Sun's ember core will crystallise as well,
leaving a giant diamond in the centre of our
"Our Sun will become a
diamond that truly is forever," says
sees 'most distant object'
By Jonathan Amos
BBC News Online science staff, in Seattle
The farthest object in the
Universe yet detected has been seen by scientists
using the Hubble and Keck telescopes.
It is so distant its light must
have set out when the Universe was just 750m
years old to reach the Earth now.
Details of the discovery were
revealed by a team of astrophysicists from the
California Institute of Technology.
They said the work underlined
again the remarkable capabilities of Hubble and
called on Nasa to reverse its decision to stop
servicing the telescope.
The US space agency has
confirmed it will not send another shuttle to
upgrade the space telescope, which probably means
Hubble has no more than three years of full
observations ahead of it.
"We need Hubble... we
could not have made this discovery without
it," said Caltech's Richard Ellis, who was
explaining his institute's latest work at the
annual meeting of the American Association for
the Advancement of Science here in Washington
"One of the instruments
that would be placed on the telescope is a new
infrared camera which would be perfect for the
work we want to do.
"Many of us hope the
decision to abandon further visits to Hubble will
be examined very carefully because the scientific
potential is very great."
The new object was first seen
in a series of observations of a cluster of
galaxies known as Abell 2218, conducted with
Hubble's Advanced Camera for Surveys, installed
on its last servicing mission.
The object is not in the
cluster but situated a long way behind it. Abell
2218 was simply used as a "gravitational
lens" - a massive foreground object that can
bend and magnify the light of objects much
Gravitational lensing is a
remarkable astronomical trick, first predicted by
Einstein, that allows scientists to probe regions
of the Universe that are estimated to be 13bn
light-years away - to look back in time to when
some of the very first stars were shining.
The Hubble images were analysed
to work out the new object's redshift, which
measures the degree to which its light is being
stretched by the expansion of the Universe.
The greater the redshift, the
more distant the object and the earlier it is
being seen in cosmic history.
The Hubble data suggested a
redshift of 6.6, but follow-up observations with
the 10-metre Keck telescopes on Hawaii indicated
the new object probably has a redshift closer to
7.0 - a record.
"The new object is a small
and compact system of stars," said Professor
Ellis. "It's about 2,000 light-years across;
our own galaxy by comparison is about 60,000
"It is forming stars
prodigiously and is a very energetic source, so
it may be an example of an object from that early
time [just after the "Dark Ages"] that
is the first of its kind to form in the
The term "Dark Ages"
was coined by the English Astronomer Royal, Sir
Martin Rees, to signify the period in cosmic
history when hydrogen atoms first formed but
stars had not yet had the opportunity to condense
Nobody is quite clear how long
this phase lasted, and the detailed study of the
cosmic sources that brought this period to an end
is a major goal of modern cosmology.
The latest discovery has been
written up for a forthcoming paper in the
Astrophysical Journal. The lead author is Caltech
astronomer Jean-Paul Kneib.
passed by on January 14th, during what the
astronomers described as a "nine-hour
crisis". Fortunately earth's magnetism did
not attract this old remnant of a better world.
The object has been called 2004AS1 maybe
mirroring the astronomical simpletons we have in
global governments. The bit of rock had to get on
the internet before it was truly identified! How
about that? An amateur astronomer analysed the
photographs and recognised that an approach after
24hours was six times closer to Earth.
Unfortunately for the professionals their
telescopes "were obscured by cloud" and
prevented them presenting this intelligence
first! Clouds and fog....? (jb.ed.)
.MC NEIL'S NEBULA - AMATEUR ASTRONOMER
FINDS NEW STAR
amateur astronomer in the US has detected the
emergence of a young star from the cocoon of gas
and dust in which it was born. Such an event has
only rarely been recorded by astronomers.
'From my back
The new object was
first spotted on 23 January by amateur astronomer
Jay McNeil from his observatory at Paducah in
discovery was quite serendipitous in
nature," he told BBC News Online.
While looking at
star formation regions in the constellation of
Orion, he noticed a star not present in previous
"I have spent
countless hours seeking out the darkest of skies
and peering into the largest of telescopes at
distant galaxies, so who would have known that I
would take an image of a famous object with a
small telescope from my back yard and find a
sun-like star being born."
The new object had
appeared alongside the well-known gas cloud known
as Messier 78.
The new object was
just a faint smudge. I contacted Brian Skiff at
the Lowell Observatory who also realised it was
new," says McNeil.
Suspecting that it
was a young star that had just broken out of its
birth cloud of gas and dust, McNeil then
contacted star formation expert Bo Reipurth.
for follow-up observations to be carried out
using the University of Hawaii 2.2 metre
telescope, and then using the giant 8-metre
Gemini telescope, also in Hawaii.
McNeil was amazed
at the train of events following his discovery,
"The idea that this thing, first seen on my
3-inch telescope, which one can easily hold using
one hand, would be observed, within 48 hours, by
a telescope of 342 tons was absolutely
observations Reipurth told BBC News Online:
"The young star was embedded in its
placental nebula. Now it has brightened, and like
a lighthouse it is casting its light across the
landscape of dust and gas around it."
"We know of
many small nebula like this scattered throughout
the sky but it is very rare to see an event like
this. We know very little about these objects and
do not know what to expect next."
An urgent appeal
has gone out to astronomers to monitor the object
which is now known as McNeil's nebula.
"We will lose
it in about six weeks when Orion goes behind the
Sun. We will then have to wait until the autumn
for it to be observable again. I expect it will
have changed by then," says Reipurth.
to have found it and to be a part of such a great
effort," says McNeil.