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Archive for September, 2013

A&A Press Release – No Evidence Of Planetary Influence On Solar Activity

September 6, 2013 Leave a comment

Image Credit: Swedish Solar Telescope at the Roque de los Muchachos Observatory

Image Credit: Swedish Solar Telescope at the Roque de los Muchachos Observatory

In 2012, Astronomy & Astrophysics published a statistical study of the isotopic records of solar activity, in which Abreu et al. claimed that there is evidence of planetary influence on solar activity. A&A is publishing a new analysis of these isotopic data by Cameron and Schüssler. It corrects technical errors in the statistical tests performed by Abreu et al. They find no evidence of any planetary effect on solar activity.

The Sun is a magnetically active star. Its activity manifests itself as dark sunspots and bright faculae on its visible surface, as well as violent mass ejections and the acceleration of high-energy particles resulting from the release of magnetic energy in its outer atmosphere. The frequency with which these phenomena occur varies in a somewhat irregular activity cycle of about 11 years, during which the global magnetic field of the Sun reverses. The solar magnetic field and the activity cycle originate in a self-excited dynamo mechanism based upon convective flows and rotation in the outer third of the solar radius.

Systematic observations of sunspots since the beginning of the 17th century indicate that solar activity also varies on longer timescales, including periods of very low activity, such as the so-called Maunder minimum between 1640 and 1700.

Full Story: http://www.aanda.org/index.php?option=com_content&task=view&id=966&Itemid=277

Coldest Brown Dwarfs Blur Lines Between Stars And Planets

September 6, 2013 Leave a comment

Astronomers are constantly on the hunt for ever-colder star-like bodies, and two years ago a new class of objects was discovered by researchers using NASA’s WISE space telescope. However, until now no one has known exactly how cool their surfaces really are – some evidence suggested they could be room temperature.

A new study shows that while these brown dwarfs, sometimes called failed stars, are indeed the coldest known free-floating celestial bodies, they are warmer than previously thought with temperatures about 250-350 degrees Fahrenheit.

To reach such low surface temperatures after cooling for billions of years means that these objects can only have about 5 to 20 times the mass of Jupiter. Unlike the Sun, these objects’ only source of energy is from their gravitational contraction, which depends directly on their mass.

“If one of these objects was found orbiting a star, there is a good chance that it would be called a planet,” says Trent Dupuy, a Hubble Fellow at the Harvard-Smithsonian Center for Astrophysics. But because they probably formed on their own and not in a proto-planetary disk, astronomers still call these objects brown dwarfs even if they are “planetary mass.”

Full Story: http://www.cfa.harvard.edu/news/2013/pr201323.html

Powerful Jets Blowing Material Out Of Galaxy

September 6, 2013 Leave a comment

Astronomers using a worldwide network of radio telescopes have found strong evidence that a powerful jet of material propelled to nearly light speed by a galaxy’s central black hole is blowing massive amounts of gas out of the galaxy. This process, they said, is limiting the growth of the black hole and the rate of star formation in the galaxy, and thus is a key to understanding how galaxies develop.

Astronomers have theorized that many galaxies should be more massive and have more stars than is actually the case. Scientists proposed two major mechanisms that would slow or halt the process of mass growth and star formation — violent stellar winds from bursts of star formation and pushback from the jets powered by the galaxy’s central, supermassive black hole.

“With the finely-detailed images provided by an intercontinental combination of radio telescopes, we have been able to see massive clumps of cold gas being pushed away from the galaxy’s center by the black-hole-powered jets,” said Raffaella Morganti, of the Netherlands Institute for Radio Astronomy and the University of Groningen.

Full Story: http://www.nrao.edu/pr/2013/jetblowout/

Dramatic Pairing Of Crescent Moon And Venus On September 8th

September 3, 2013 1 comment

Soon after the Sun dips below the western horizon on Sunday, September 8th, anyone looking in that direction will see a dramatic sight: a pretty crescent Moon paired closely with the dazzling planet Venus, the “Evening Star.”

“This is one you won’t want to miss,” says Alan MacRobert of Sky & Telescope magazine. “These are the two brightest objects in the nighttime sky.”

Start looking for the pair about 30 minutes after sunset. The farther south and east you are in North America, the closer they’ll appear. From locations along the East Coast, the they’ll be only about 1½° apart — about the width of your index finger at arm’s length. By the time darkness falls on the West Coast, the Moon will have edged slightly farther away.

Full Story: http://www.skyandtelescope.com/about/pressreleases/Moon-and-Venus-September-8th.html

UK Scientists Begin 5 Year Quest To Solve Cosmic Detective Puzzle

September 3, 2013 1 comment

A five year quest is underway (3 September 2013) looking to solve the cosmic detective puzzle of why the expansion of the universe is speeding up. UK physicists and astronomers working alongside colleagues from around the world, from an observatory in Chile, are using the world’s most powerful digital camera – the Dark Energy Camera – to try and answer some of the most fundamental questions about our universe.

For hundreds of nights over the next five years, the researchers taking part in this Dark Energy Survey (DES) aim to find out not only why the growth of the universe is accelerating, instead of slowing down due to gravity, but also to probe the mystery of dark energy, the force believed to be causing that acceleration.

Scientists on the survey team will systematically map one-eighth of the sky (5000 square degrees) in unprecedented detail. The start of the survey is the culmination of ten years of planning, building, and testing by scientists from 25 institutions in six countries, including the Universities of Cambridge, Edinburgh, Nottingham, Portsmouth, Sussex and University College London in the UK.

Full Story: http://www.stfc.ac.uk/2841.aspx

The World’s First Interferometric Image At 500 GHz With ALMA Band 8 Receivers

September 3, 2013 1 comment

Credit: ALMA (ESO/NAOJ/NRAO)

Credit: ALMA (ESO/NAOJ/NRAO)

ALMA opens another window to the universe in the 500 GHz frequency band. Astronomers successfully synthesized the distribution of atomic carbon around a planetary nebula NGC 6302 in test observations with the ALMA Band 8 receiver, developed by the National Astronomical Observatory of Japan (NAOJ). This is the first 500 GHz band astronomical image captured by a radio interferometer with unprecedentedly high resolution.

NGC 6302 is a planetary nebula, which is in the final stage of the life of a star with a mass several times that of the Sun. Visible light image shows a bipolar shape of gas ejected from the dying star. ALMA with the Band 8 receivers targeted at the center of the nebula and revealed that the distribution of carbon atom is concentrated in a small part, which is similar to a dust and gas disk around the central star that has been found by previous observations with other telescopes. Further observations of carbon atom with better resolution will give us more detailed view of the chemical environment in the nebula.

Full Story: http://www.nao.ac.jp/en/news/topics/2013/20130902-alma-band8.html

Massive Storm Pulls Water And Ammonia Ices From Saturn’s Depths

September 3, 2013 1 comment

Once every 30 years or so, or roughly one Saturnian year, a monster storm rips across the northern hemisphere of the ringed planet.

In 2010, the most recent and only the sixth giant storm on Saturn observed by humans began stirring. It quickly grew to superstorm proportions, reaching 15,000 kilometers (more than 9,300 miles) in width and visible to amateur astronomers on Earth as a great white spot dancing across the surface of the planet.

Now, thanks to near-infrared spectral measurements taken by NASA’s Cassini orbiter and analysis of near-infrared color signatures by researchers at UW-Madison, Saturn’s superstorm is helping scientists flesh out a picture of the composition of the planet’s atmosphere at depths typically obscured by a thick high-altitude haze.

Full Story: http://www.news.wisc.edu/22083