午夜福利1000集合

STARS being born deep inside the Eagle Nebula have been caught on camera for
the first time. The nebula鈥檚 impressive 鈥減illars of creation鈥� were thought to
contain nascent stars, but telescopes were unable to penetrate the dust
surrounding them. Now an infrared camera called ISAAC has cut through the
clouds.

In 1995, the Eagle Nebula became famous overnight when Jeff Hester of Arizona
State University in Tempe published a stunning image of it taken by the Hubble
Space Telescope (New Scientist, 11 November 1995, p 6). The nebula
used to be much bigger, but ultraviolet radiation from nearby stars has blown away
most of the dust that made up the cloud, in a process known as
photoevaporation.

According to Hester, dozens of small protrusions on the dark, dusty pillars
were harbouring embryonic stars. He called the protrusions鈥攚hich are each
about the size of our Solar System鈥攅vaporating gaseous globules or EGGs.
He reasoned that the protrusions are parts of the nebula that are in the shadow
of young stars and are therefore partly protected from radiation. As the
globules continued to be eroded, the young hatchlings would be revealed
prematurely.

But until now it hasn鈥檛 been possible to tell if stars really are being
hatched, mainly because Hubble couldn鈥檛 see inside the dusty globules. 鈥淢y
suspicion was that Hester was wrong,鈥� says Mark McCaughrean of the Astrophysical
Institute in Potsdam, Germany. Looking at infrared wavelengths, which penetrate
dust, would settle the issue, but until recently images from infrared detectors
were not as sharp as those from Hubble.

Then the infrared ISAAC camera on the Very Large Telescope (VLT) in Chile
came online. The camera combines a large field of view with a high sensitivity
and very acute vision. McCaughrean and his colleague Morten Andresen used ISAAC
to capture a near-infrared image of the Eagle Nebula in April and May last year.
A paper describing their results will be published in Astronomy
and Astrophysics.

McCaughrean and Andresen carefully aligned the VLT image with Hester鈥檚
original Hubble photograph, and found that while most of the globules appear
sterile, 11 of the original 73 EGGs seem to be hatching low-mass stars or brown
dwarfs. 鈥淗ester鈥檚 original idea might be valid,鈥� says McCaughrean.

Hester is ecstatic about the result. 鈥淭he EGGs are every bit as interesting
as we originally thought.鈥� He says that because the dust is being eroded, many
of the stars emerging from the nebula have a lower mass than they would have had
otherwise.