Archive for May 2, 2013

An Anarchic Region Of Star Formation

Credit: ESO

Credit: ESO

The Danish 1.54-metre telescope located at ESO’s La Silla Observatory in Chile has captured a striking image of NGC 6559, an object that showcases the anarchy that reigns when stars form inside an interstellar cloud.

NGC 6559 is a cloud of gas and dust located at a distance of about 5000 light-years from Earth, in the constellation of Sagittarius (The Archer). The glowing region is a relatively small object, just a few light-years across, in contrast to the one hundred light-years and more spanned by its famous neighbour, the Lagoon Nebula (Messier 8, eso0936). Although it is usually overlooked in favour of its distinguished companion, NGC 6559 has the leading role in this new picture.

The gas in the clouds of NGC 6559, mainly hydrogen, is the raw material for star formation. When a region inside this nebula gathers enough matter, it starts to collapse under its own gravity. The centre of the cloud grows ever denser and hotter, until thermonuclear fusion begins and a star is born. The hydrogen atoms combine to form helium atoms, releasing energy that makes the star shine.

But NGC 6559 is not just made out of hydrogen gas. It also contains solid particles of dust, made of heavier elements, such as carbon, iron or silicon.

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New Dark Matter Detector Begins Search For Invisible Particles

Scientists this week heard their first pops in an experiment that searches for signs of dark matter in the form of tiny bubbles. Scientists will need further analysis to discern whether dark matter caused any of the COUPP-60 experiment’s first bubbles. “Our goal is to make the most sensitive detector to see signals of particles that we don’t understand,” said Hugh Lippincott, a postdoc with the Department of Energy’s Fermi National Accelerator Laboratory who has spent much of the past several months leading the installation of the one-of-a-kind detector in a laboratory a mile and a half underground.

COUPP-60 is a dark-matter experiment funded by DOE’s Office of Science. Fermilab managed the assembly and installation of the experiment’s detector. The COUPP-60 detector is a jar filled with purified water and CF3I—an ingredient found in fire extinguishers. The liquid in the detector is kept at a temperature and pressure slightly above the boiling point, but it requires an extra bit of energy to actually form a bubble. When a passing particle enters the detector and disturbs an atom in the clear liquid, it provides that energy.

Dark-matter particles, which scientists think rarely interact with other matter, should form individual bubbles in the COUPP-60 tank. “The events are so rare, we’re looking for a couple of events per year,” Lippincott said.

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