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New Theory Points To ‘Zombie Vortices’ As Key Step In Star Formation

August 21, 2013 Leave a comment

Artist conception. Image courtesy of NASA/JPL-Caltech

Artist conception. Image courtesy of NASA/JPL-Caltech

A new theory by fluid dynamics experts at the University of California, Berkeley, shows how “zombie vortices” help lead to the birth of a new star.

Reporting today (Tuesday, Aug. 20) in the journal Physical Review Letters, a team led by computational physicist Philip Marcus shows how variations in gas density lead to instability, which then generates the whirlpool-like vortices needed for stars to form.

Astronomers accept that in the first steps of a new star’s birth, dense clouds of gas collapse into clumps that, with the aid of angular momentum, spin into one or more Frisbee-like disks where a protostar starts to form. But for the protostar to grow bigger, the spinning disk needs to lose some of its angular momentum so that the gas can slow down and spiral inward onto the protostar. Once the protostar gains enough mass, it can kick off nuclear fusion.

Full Story: http://newscenter.berkeley.edu/2013/08/20/zombie-vortices-key-step-in-star-formation/

Rosetta-Comet Will Wake Up Early

August 21, 2013 1 comment

Two months after ESA’s space probe Rosetta starts its approach towards Churyumov-Gerasimenko, the comet will show activity. This is earlier than expected.

On its way towards the Sun comet Churyumov-Gerasimenko, next year’s destination of ESA’s spacecraft Rosetta, will start emitting gas and dust earlier than previously expected. The comet’s activity should be measurable from Earth by March 2014. This is one of the results of a new study performed by a group of researchers under the lead of the Max Planck Institute for Solar System Research (MPS) in Germany. The scientists analyzed numerous images from the comet’s past three orbits around the Sun, obtained with ground based telescopes. For the first time, they were able to reconstruct the comet’s activity in all phases of its orbit.

A comet spends the main part of its existence far from the Sun as an unchanged lump of ice and rock. When it approaches the Sun, however, a metamorphosis takes place: highly volatile substances vaporize from the nucleus carrying fountains of dust particles with them. These accumulate to form the comet’s atmosphere, the coma, and are the origin of its tail, a comet’s most characteristic feature. However, the principles governing these processes are still only poorly understood. What instances spark the ejection of gas and dust? How does this activity evolve? And which processes on the surface and within the comet’s nucleus are decisive?

Next year, ESA’s spacecraft Rosetta will try to answer these questions.

Full Story: http://www.mps.mpg.de/en/aktuelles/pressenotizen/pressenotiz_20130820.html

Naked-Eye Nova In Delphinus

August 21, 2013 1 comment

Last Wednesday a white-dwarf star erupted in the constellation Delphinus, producing the brightest nova since 2007. Currently shining at magnitude 4.9, the nova is visible to the naked eye from dark locations far from city lights, and might remain so for weeks to come.

“The nova is easy to locate north of the lovely star pattern of Delphinus. And the constellation Sagitta, the Arrow, points right toward it,” says Tony Flanders, associate editor of Sky & Telescope and host of S&T’s PBS TV show SkyWeek.

“A second advantage is the nova’s location. It’s easily visible in the eastern sky in the early evening, so it can be followed for many hours. This means that amateur skygazers and professional scientists alike can continue monitoring it for months to come,” adds Arne Henden, director of the American Association of Variable Star Observers (AAVSO). “The nova can be seen with binoculars even from light-polluted metropolitan areas. Hundreds of observers, many for the first time, have submitted brightness estimates of the nova to the AAVSO.”

Full Story: http://www.skyandtelescope.com/about/pressreleases/Naked-eye-Nova-in-Delphinus-220235341.html

Waking Up To A New Year: MIT Team Discovers An Exoplanet That Orbits Its Star In 8.5 Hours

August 21, 2013 1 comment

In the time it takes you to complete a single workday, or get a full night’s sleep, a small fireball of a planet 700 light-years away has already completed an entire year.

Researchers at MIT have discovered an Earth-sized exoplanet named Kepler 78b that whips around its host star in a mere 8.5 hours — one of the shortest orbital periods ever detected. The planet is extremely close to its star — its orbital radius is only about three times the radius of the star — and the scientists have estimated that its surface temperatures may be as high as 3,000 degrees Kelvin, or more than 5,000 degrees Fahrenheit. In such a scorching environment, the top layer of the planet is likely completely melted, creating a massive, roiling ocean of lava.

What’s most exciting to scientists is that they were able to detect light emitted by the planet — the first time that researchers have been able to do so for an exoplanet as small as Kepler 78b. This light, once analyzed with larger telescopes, may give scientists detailed information about the planet’s surface composition and reflective properties.

Full Story: http://web.mit.edu/newsoffice/2013/kepler-78b-exoplanet-0819.html

ALMA Takes Close Look At Drama Of Starbirth

August 21, 2013 Leave a comment

Credit: ESO / ALMA (ESO / NAOJ / NRAO) / H. Arce. Acknowledgements: Bo Reipurth

Credit: ESO / ALMA (ESO / NAOJ / NRAO) / H. Arce. Acknowledgements: Bo Reipurth

Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have obtained a vivid close-up view of material streaming away from a newborn star. By looking at the glow coming from carbon monoxide molecules in an object called Herbig-Haro 46/47 they have discovered that its jets are even more energetic than previously thought. The very detailed new images have also revealed a previously unknown jet pointing in a totally different direction.

Young stars are violent objects that eject material at speeds as high as one million kilometres per hour. When this material crashes into the surrounding gas it glows, creating a Herbig-Haro object. A spectacular example is named Herbig-Haro 46/47 and is situated about 1400 light-years from Earth in the southern constellation of Vela (The Sails). This object was the target of a study using ALMA during the Early Science phase, whilst the telescope was still under construction and well before the array was completed.

The new images reveal fine detail in two jets, one coming towards Earth and one moving away. The receding jet was almost invisible in earlier pictures made in visible light, due to obscuration by the dust clouds surrounding the new-born star. ALMA has not only provided much sharper images than earlier facilities but also allowed astronomers to measure how fast the glowing material is moving through space.

Full Story: http://www.eso.org/public/news/eso1336/
Also: http://news.yale.edu/2013/08/20/they-form-stars-shape-their-womb-within