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Exoplanet Hosting Stars Give Further Insights On Planet Formation

August 16, 2012 Leave a comment

An international team, led by EXOEarths researchers (Centro de Astrofísica da Universidade do Porto – CAUP), proposes that metals like Magnesium might have an important role in the formation of low mass planets.

The team, lead by CAUP researcher Vardan Zh. Adibekyan, analyzed high resolution spectra of 1111 sun-like stars, obtained by the HARPS spectrograph (ESO). Of these stars, 109 are known to harbor high mass (Jupiter-like) planets, and 26 have Neptune-like planetary companions.

The team focused especially on studying the abundance of Alpha Elements in these stars, like Magnesium (Mg), Silicon (Si) or Titanium (Ti). The research found that the ratio of these, compared with the amount of Iron (Fe), was consistently higher in stars with planets, with the greatest discrepancy observed for Mg.

Full Story: http://www.alphagalileo.org/ViewItem.aspx?ItemId=123234&CultureCode=en

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Hubble Watches Star Clusters On A Collision Course

August 16, 2012 Leave a comment

Image Credit: NASA, ESA, and E. Sabbi (ESA/STScI)

Astronomers using data from NASA’s Hubble Space Telescope have caught two clusters full of massive stars that may be in the early stages of merging. The clusters are 170,000 light-years away in the Large Magellanic Cloud, a small satellite galaxy to our Milky Way.

What at first was thought to be only one cluster in the core of the massive star-forming region 30 Doradus (also known as the Tarantula Nebula) has been found to be a composite of two clusters that differ in age by about one million years.

Lead scientist Elena Sabbi of the Space Telescope Science Institute in Baltimore, Md., and her team began looking at the area while searching for runaway stars, fast-moving stars that have been kicked out of their stellar nurseries where they first formed. “Stars are supposed to form in clusters, but there are many young stars outside 30 Doradus that could not have formed where they are; they may have been ejected at very high velocity from 30 Doradus itself,” Sabbi said.

Full Story: http://hubblesite.org/newscenter/archive/releases/2012/35/full/

Giant Galaxy Cluster Sets Record Pace For Creating Stars

August 16, 2012 Leave a comment

Courtesy of South Pole Telescope collaboration

Astronomers have found an extraordinary galaxy cluster — one of the largest objects in the universe — that is breaking several important cosmic records. The discovery of this cluster, known as the Phoenix Cluster, made with the National Science Foundation’s South Pole Telescope, may force astronomers to rethink how these colossal structures, and the galaxies that inhabit them, evolve.

Follow-up observations made in ultraviolet, optical and infrared wavelengths show that stars are forming in this object at the highest rate ever seen in the middle of a galaxy cluster. The object also is the most powerful producer of X-rays of any known cluster, and among the most massive of clusters. The data also suggest that the rate of hot gas cooling in the central regions of the cluster is the largest ever observed.

Full Story: http://news.uchicago.edu/article/2012/08/15/giant-galaxy-cluster-sets-record-pace-creating-stars

Phoenix Cluster Sets Record Pace At Forming Stars

August 16, 2012 Leave a comment

Credit: X-ray: NASA/CXC/MIT/
M.McDonald; UV: NASA/JPL
-Caltech/M.McDonald;
Optical: AURA/NOAO/CTIO/
MIT/M.McDonald;
Illustration: NASA/CXC/M.Weiss

Stars are forming in the Phoenix cluster at the highest rate ever observed for the middle of a galaxy cluster. The object also is the most powerful producer of X-rays of any known cluster and among the most massive. The data also suggest the rate of hot gas cooling in the central regions of the cluster is the largest ever observed.

“While galaxies at the center of most clusters may have been dormant for billions of years, the central galaxy in this cluster seems to have come back to life with a new burst of star formation,” said Michael McDonald, a Hubble Fellow at the Massachusetts Institute of Technology and the lead author of a paper appearing in the Aug. 16 issue of the journal Nature. “The mythology of the Phoenix, a bird rising from the dead, is a great way to describe this revived object.”

Like other galaxy clusters, Phoenix contains a vast reservoir of hot gas, which itself holds more normal matter — not dark matter — than all of the galaxies in the cluster combined. This reservoir can be detected only with X-ray telescopes such as Chandra. The prevailing wisdom once had been that this hot gas should cool over time and sink to the galaxy at the center of the cluster, forming huge numbers of stars. However, most galaxy clusters have formed very few stars during the last few billion years. Astronomers think the supermassive black hole in the central galaxy of a cluster pumps energy into the system, preventing cooling of gas from causing a burst of star formation.

Full Story: http://chandra.harvard.edu/press/12_releases/press_081512.html

Lunar Reconnaissance Orbiter Spectrometer Detects Helium In Moon’s Atmosphere

August 16, 2012 Leave a comment

Scientists using the Lyman Alpha Mapping Project (LAMP) spectrometer aboard NASA’s Lunar Reconnaissance Orbiter (LRO) have made the first spectroscopic observations of the noble gas helium in the tenuous atmosphere surrounding the moon.

“The question now becomes, does the helium originate from inside the moon or from an exterior source, such as the solar wind?” says Dr. Alan Stern.

“If we find the solar wind is responsible, that will teach us a lot about how the same process works in other airless bodies,” says Stern.

If spacecraft observations show no such correlation, radioactive decay or other internal lunar processes could be producing helium that diffuses from the interior or that is released during lunar quakes.

During its campaign, LACE also detected the noble gas argon on the lunar surface. Although significantly fainter to the spectrograph, LAMP also will seek argon and other gases during future observations.

Full Story: http://www.nasa.gov/mission_pages/LRO/news/helium-detected.html

Lunar Reconnaissance Orbiter’s LAMP Spectrometer Detects Helium In Moon’s Atmosphere, Raises Questions About Origin

August 16, 2012 Leave a comment

Scientists using the Lyman Alpha Mapping Project (LAMP) aboard NASA’s Lunar Reconnaissance Orbiter have made the first spectroscopic observations of the noble gas helium in the tenuous atmosphere surrounding the Moon. These remote-sensing observations complement in-situ measurements taken in 1972 by the Lunar Atmosphere Composition Experiment (LACE) deployed by Apollo 17.

Although LAMP was designed to map the lunar surface, the team expanded its science investigation to examine the far ultraviolet emissions visible in the tenuous atmosphere above the lunar surface, detecting helium over a campaign spanning more than 50 orbits. Because helium also resides in the interplanetary background, several techniques were applied to remove signal contributions from the background helium and determine the amount of helium native to the Moon. Geophysical Research Letters published a paper on this research in 2012.

“The question now becomes, does the helium originate from inside the Moon, for example, due to radioactive decay in rocks, or from an exterior source, such as the solar wind?” says Dr. Alan Stern, LAMP principal investigator and associate vice president of the Space Science and Engineering Division at Southwest Research Institute.

Full Story: http://swri.org/9what/releases/2012/lro-lamp.htm

Astronomers Reassured by Record-breaking Star Formation In Huge Galaxy Cluster

August 16, 2012 Leave a comment

Image courtesy of the Chandra X-ray Observatory

Until now, evidence for what astronomers suspect happens at the cores of the largest galaxy clusters has been uncomfortably scarce. Theory predicts that cooling flows of gas should sink toward the cluster’s center, sparking extreme star formation there, but so far – nada, zilch, not-so-much.

The situation changed dramatically when a large international team of over 80 astronomers, led by Massachusetts Institute of Technology’s Hubble Fellow Michael McDonald, studied a recently discovered (yet among the largest-known) galaxy cluster. The team found evidence for extreme star formation, or a starburst, significantly more extensive than any seen before in the core of a giant galaxy cluster. “It is indeed reassuring to see this process in action,” says McDonald. “Further study of this system may shed some light on why other clusters aren’t forming stars at these high rates, as they should be.”

“Our first observations of this cluster with the Gemini South telescope in Chile really helped to ignite this work,” says McDonald. “They were the first hints that the central galaxy in this cluster was such a beast!” The paper’s second author, Matthew Bayliss of Harvard University, adds, “When I first saw the Gemini spectrum, I thought we must have mixed up the spectra, it just looked so bizarre compared to anything else of its kind.”

Full Story: http://www.gemini.edu/node/11853