Kategorie: Kosmologie

Engineers are ready to begin integrating the scientific instruments into ESA’s Planck satellite. The pair of instruments will allow the spacecraft to make the most precise map yet of the cosmic microwave background, a relic radiation left behind by the formation of the Universe. The integration of Planck’s two instruments marks a major milestone for the mission, which is scheduled to launch in mid-2008.
Planck @ ESA

Dr. Bringfried Stecklum, Wissenschaftler an der Thüringer Landessternwarte Tautenburg (TLS), hat mit dem 2-m Alfred-Jensch-Teleskop des Instituts einen jungen Stern im Sternbild Giraffe entdeckt, dessen Helligkeit innerhalb kurzer Zeit um das Dreißigfache zunahm. Der Stern gehört zur Klasse von Objekten, die nach ihren Prototypen, den veränderlichen Sternen FU im Sternbild Orion und EX im Sternbild Wolf, als FUore bzw. EXore bezeichnet werden. Von ihnen sind bisher nur etwa ein Dutzend bekannt. Das neue Mitglied weist von allen die bei weitem geringste Leuchtkraft und damit auch die kleinste Masse auf. Es konnte nur gefunden werden, weil der starke Anstieg der Helligkeit zu einer besseren Ausleuchtung der Gas- und Staubwolke führte, aus der sich der Stern bildete. Der dabei entstandene neue Nebel ist auf Archivaufnahmen aus dem Jahr 2001 noch nicht zu sehen! Der Helligkeitsanstieg vollzog sich daher innerhalb von fünf Jahren. Er weist auf eine Phase besonders intensiven Wachstums des Sterns hin.
Junge Sterne sind von einer Scheibe aus Gas und Staub umgeben. Sie wachsen, indem Materie aus der Scheibe auf sie herabfällt. Dabei wird die beim Aufprall freigesetzte Energie als Strahlung abgegeben. Die starke Helligkeitszunahme weist also auf eine Episode besonders intensiven Masseneinfalls hin. Bei EXoren kann diese Monate und Jahre andauern; bei FUoren sogar Jahrzehnte.
Die Thüringer Landessternwarte Tautenburg liegt zirka 15 Kilometer nördlich der Universitätsstadt Jena. Das astronomische Institut forscht auf den Gebieten der stellaren Astrophysik und der extragalaktischen Astronomie. Forschungsschwerpunkte sind die Suche nach extrasolaren Planeten, die Entstehung und das Sterben von Sternen, Gamma-Ray Bursts sowie die Entwicklung von Galaxien. Die Thüringer Landessternwarte Tautenburg betreibt das größte optische Teleskop Deutschlands.

Astronomers have identified 20 new stellar systems in our local solar neighbourhood, including the twenty-third and twenty-fourth closest stars to the Sun. When added to eight other systems announced by this team and six by other groups since 2000, the known population of the Milky Way galaxy within 33 light-years of Earth has grown by 16 percent in just the past six years. The discoveries were made by a group called the „Research Consortium on Nearby Stars“ (RECONS), which has been using small telescopes at the National Science Foundation’s Cerro Tololo Inter-American Observatory in the Chilean Andes since 1999. The new results will appear in the December 2006 issue of the Astronomical Journal.
https://noirlab.edu/public/news/noao0615/

A large survey, made with ESO’s VLT, has shed light on our Galaxy’s ancestry. After determining the chemical composition of over 2000 stars in four of the nearest dwarf galaxies to our own, astronomers have demonstrated fundamental differences in their make-up, casting doubt on the theory that these diminutive galaxies could ever have formed the building blocks of our Milky Way Galaxy.
Cut from Different Cloth

A new image from NASA’s Spitzer and Hubble Space Telescopes looks more like an abstract painting than a cosmic snapshot. The masterpiece shows the Orion nebula in an explosion of infrared, ultraviolet and visible-light colors.
https://www.spitzer.caltech.edu/news/ssc2006-21-spitzer-and-hubble-create-colorful-masterpiece

Scientists using NASA’s Swift satellite have spotted a stellar flare on a nearby star so powerful that, had it been from our sun, it would have triggered a mass extinction on Earth. The flare was perhaps the most energetic magnetic stellar explosion ever detected. The flare was seen in December 2005 on a star slightly less massive than the sun, in a two-star system called II Pegasi in the constellation Pegasus. It was about a hundred million times more energetic than the sun’s typical solar flare, releasing energy equivalent to about 50 million trillion atomic bombs. Fortunately, our sun is now a stable star that doesn’t produce such powerful flares. And II Pegasi is at a safe distance of about 135 light-years from Earth.
https://www.nasa.gov/mission_pages/swift/bursts/monster_flare.html

The Hubble Space Telescope, the Chandra X-Ray Observatory, and the National Radio Astronomical Observatory teamed up to produce a composite image of galaxy cluster MS0735.6+7421, located about 2.5 billion light-years from Earth. The cluster in the constellation Camelopardus contains dozens of galaxies held together by gravity. A truly supermassive black hole lurks at the heart of this cluster, containing more than a billion solar masses. The red areas which are visible in the picture are twin jets of material streaming away from the black hole.

https://hubblesite.org/contents/media/images/2006/51/2009-Image.html

https://chandra.harvard.edu/photo/2006/ms0735/

An international team of researchers used Gemini mid-infrared images to investigate a sample of nearby Luminous InfraRed Galaxies (LIRGs) which are analogous to those LIRGs which are major contributors to the obscured star formation rate (SFR) density at redshift z=1, when the universe was half of its present age.

https://www.gemini.edu/node/210

Robert A. Simcoe of the MIT-Kavli Center for Astrophysics and Space Research has found new evidence of intensive heavy-element enrichment in intergalactic gas, occurring less than 1 billion years after the Big Bang.

https://www.gemini.edu/node/211

The dust that condensed to form the sun, the Earth and the stuff of human bodies has long been thought to have originated in violent explosions of giant stars. But these explosions – called supernovae – can’t account for all the dust in the cosmos. Now, observations with NASA’s Spitzer Space Telescope, led by University of Minnesota astrophysicists, have found cosmic dust where it had never been found before. The finding implies that the deaths of smaller stars may have supplied the early dust that seeded the myriad stars like our sun, and produced dust more efficiently than the big guns.

New observations of star cluster by U of M researchers help settle the dust on sun’s origin

Stellar Populations and Mass-Loss in M15: A Spitzer Detection of Dust in the Intra-Cluster Medium