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Astronomers pinpoint elusive galaxy after decade-long hunt

June 13, 2012 Leave a comment

An international team of astronomers led by Fabian Walter of the Max Planck Institute for Astronomy has managed for the first time to determine the distance of the galaxy HDF850.1, well-known among astronomers as being one of the most productive star-forming galaxies in the observable universe. The galaxy is at a distance of 12.5 billion light years. Hence, we see it as it was 12.5 billion years ago, when the universe was less than 10% of its current age. Even more of a surprise, HDF850.1 turns out to be part of a group of around a dozen protogalaxies that formed within the first billion years of cosmic history — only one of two such primordial clusters known to date. The work is being published in the journal Nature.
The galaxy HDF850.1 was discovered in 1998. It is famous for producing new stars at a rate that is near-incredible even on astronomical scales: a combined mass of a thousand Suns per year. For comparison: an ordinary galaxy such as our own produces no more than one solar mass’s worth of new stars per year. Yet for the past fourteen years, HDF850.1 has remained strangely elusive — its location in space, specifically: its distance from Earth the subject of many studies, but ultimately unknown. How was that possible?
The “Hubble Deep Field”, where HDF850.1 is located, is a region in the sky that affords an almost unparalleled view into the deepest reaches of space. It was first studied extensively using the Hubble Space Telescope. Yet observations using visible light only reveal part of the cosmic picture, and astronomers were quick to follow-up at different wavelengths. In the late 1990s, astronomers using the James Clerk Maxwell Telescope on Hawai’i surveyed the region using submillimeter radiation. This type of radiation, with wavelengths between a few tenths of a millimeter and a millimeter, is particularly suitable for detecting cool clouds of gas and dust.

Full Story: http://www.mpia.de/Public/menu_q2.php?Aktuelles/PR/2012/PR120613/PR_120613_en.html

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Planets can form around different types of stars

June 13, 2012 Leave a comment

It had previously been thought that planets were more likely to form around a star if the star had a high content of heavier elements. But new research from the University of Copenhagen, among others, shows that small planets can form around very different types of stars — also stars that are relatively poor in heavy elements. This significantly increases the likelihood that Earth-like planets are widespread in the universe. The results have been published in the prestigious scientific journal, Nature.
3,000 exoplanets, i.e., planets orbiting a star other than the Sun, have now been discovered. 2,300 of these potential planets are being observed with the Kepler satellite by measuring the brightness of the host stars. If a planet moves in front of its star, there is a small decrease in the brightness and if this happens repeatedly, it could be a planet orbiting the star and dimming its light.
A multitude of planets have been discovered so far and by measuring their size it is possible to distinguish between gas giants like Saturn and Jupiter, or whether they are smaller, terrestrial planets like Earth and Mars.

Full Story: http://www.nbi.ku.dk/english/news

Astronomers Map 40 Million Stars

June 13, 2012 Leave a comment

Astronomers will soon have access to a new map of the sky that accurately measures the brightness and position of over 40 million stars.
This map is a result of the AAVSO Photometric All-Sky Survey, which has completely covered the sky at a level 100 times fainter than any prior stellar catalog. Millions of stars will have their brightness and color measured accurately for the first time in this survey.
“Prior surveys have done a good job measuring the brightness of bright stars. Other organizations have announced plans to measure faint stars. But this goldilocks zone of stars that are neither too bright or too faint has been neglected, until now,” Dr. Arne Henden, Director of the American Association of Variable Star Observers (AAVSO), said.
“This catalog of stars will serve a key link between existing bright catalogs and fainter catalogs planned for the future, such as those created by Pan-STARRS and the LSST observatories,” Dr. Doug Welch, a professor of Physics and Astronomy at McMaster University.

Full Story: http://aas.org/meetings/aas220

Galaxies NGC 4342, NGC 4291

June 12, 2012 Leave a comment

New results based studies of galaxies NGC 4342 and NGC 4291 are challenging the prevailing ideas as to how supermassive black holes grow in the centers of galaxies. New results based on the two objects shown here are challenging the prevailing ideas as to how supermassive black holes grow in the centers of galaxies. NGC 4342 and NGC 4291, the two galaxies in the study, are nearby in cosmic terms at distances of 75 million and 85 million light years respectively. In these composite images, X-rays from NASA’s Chandra X-ray Observatory are colored blue, while infrared data from the 2MASS project are seen in red.
Astronomers had known from previous observations that these galaxies host black holes with unusually large masses compared to the mass contained in the central bulge of stars. To study the dark matter envelopes contained in each galaxy, Chandra was used to examine their hot gas content, which was found to be widespread in both objects.
By analyzing the distribution of the hot gas, researchers were able to test whether the galaxies had “lost weight” through stars being pulled away during a tidal encounter with another galaxy. Estimates of the pressure of the hot gas, which must balance the gravitational pull of all the matter in the galaxy, showed that massive envelopes of dark matter must exist around each galaxy. Since this tidal stripping would have severely depleted the dark matter, which is more loosely tied to the galaxies than the stars, this process is unlikely to have occurred in either galaxy.

Full Story: http://www.nasa.gov/mission_pages/chandra/multimedia/ngc_4342_4291.html

Time for a Change? Calendar Overhaul Proposed

December 27, 2011 Leave a comment

Researchers at The Johns Hopkins University have discovered a way to make time stand still — at least when it comes to the yearly calendar.

Using computer programs and mathematical formulas, Richard Conn Henry, an astrophysicist in the Krieger School of Arts and Sciences, and Steve H. Hanke, an applied economist in the Whiting School of Engineering, have created a new calendar in which each new 12-month period is identical to the one which came before, and remains that way from one year to the next in perpetuity.

Under the Hanke-Henry Permanent Calendar, for instance, if  Christmas fell on a Sunday in 2012 (and it would), it will also fall on a Sunday in 2013, 2014 and beyond. In addition, under the new calendar, the rhyme “30 days hath September, April, June and November,” would no longer apply, because September would have 31 days, as would June, March and December. All the rest have 30 (Try creating a rhyme using that.)

Full Story: http://releases.jhu.edu/2011/12/27/time-for-a-change-johns-hopkins-scholars-say-calendar-needs-serious-overhaul/