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October 6, 2006, 4:53 AM CT

Black Hole Musical: Epic But Off-Key

Black Hole Musical: Epic But Off-Key Low Energy X-ray Images of M87
A gigantic sonic boom generated by a supermassive black hole has been found with NASA's Chandra X-ray Observatory, along with evidence for a cacophony of deep sound.

This discovery was made by using data from the longest X-ray observation ever of M87, a nearby giant elliptical galaxy. M87 is centrally located in the Virgo cluster of galaxies and is known to harbor one of the Universe's most massive black holes.

Scientists detected loops and rings in the hot, X-ray emitting gas that permeates the cluster and surrounds the galaxy. These loops provide evidence for periodic eruptions that occurred near the supermassive black hole, and that generate changes in pressure, or pressure waves, in the cluster gas that manifested themselves as sound.

"We can tell that many deep and different sounds have been rumbling through this cluster for most of the lifetime of the Universe," said William Forman of the Harvard-Smithsonian Center for Astrophysics (CfA).

The outbursts in M87, which happen every few million years, prevent the huge reservoir of gas in the cluster from cooling and forming many new stars. Without these outbursts and resultant heating, M87 would not be the elliptical galaxy it is today.

"If this black hole wasn't making all of this noise, M87 could have been a completely different type of galaxy," said team member Paul Nulsen, also of the CfA, "possibly a huge spiral galaxy about 30 times brighter than the Milky Way".........

Posted by: Edwin      Permalink         Source


October 4, 2006, 10:29 PM CT

Sun Was Born In Star Cluster

Sun Was Born In Star Cluster
The death of a massive nearby star billions of years ago offers evidence the sun was born in a star cluster, say astronomers at the University of Illinois at Urbana-Champaign. Rather than being an only child, the sun could have hundreds or thousands of celestial siblings, now dispersed across the heavens.

In a paper accepted for publication in the Astrophysical Journal, astronomy professors Leslie W. Looney and Brian D. Fields, and undergraduate student John J. Tobin take a close look at short-lived radioactive isotopes once present in primitive meteorites. The researchers' conclusions could reshape current theories on how, when and where planets form around stars.

Short-lived radioactive isotopes are created when massive stars end their lives in spectacular explosions called supernovas. Blown outward, bits of this radioactive material mix with nebular gas and dust in the process of condensing into stars and planets.

When the solar system was forming, some of this material hardened into rocks and later fell to Earth as meteorites.

The radioisotopes have long since vanished from meteorites found on Earth, but they left their signatures in daughter species. By examining the abundances of those daughter species, the scientists could calculate how far away the supernova was, in both distance and time.........

Posted by: Edwin      Permalink         Source


October 1, 2006, 7:10 PM CT

Stellar Birth Control In The Early Universe

Stellar Birth Control In The Early Universe Extremely massive black holes in the centers of galaxies may serve as 'cosmic contraceptives' in the early Universe, suppressing the birth of new stars.
Credit: NASA and the Hubble Heritage Team (STScI/AURA
An international team of astronomers based at Yale and Leiden University in The Netherlands found that "old stars" dominated many large galaxies in the early universe, raising the new question of why these galaxies progressed into "adulthood" so early in the life of the universe.

Every year only a handful of new stars are born out of the gas that fills the space between the stars in galaxies like the Milky Way. To account for the large number of stars in the Universe today, about 400 billion in the Milky Way alone, it was thought that the "stellar birth rate" must have been much higher in the past.

Surprisingly, in this study appearing in the October 2 issue of Astrophysical Journal, astronomers using the 8.1m Gemini telescope in Chile report that many of the largest galaxies in the Universe had a very low stellar birth rate even when the Universe was only about 20 percent of its present age.

"Our new results imply that the stars in many large galaxies were born when the Universe was in its infancy, in the first few billion years after the Big Bang," said team leader Mariska Kriek, a PhD student from Leiden University and Yale. "The results confirm what some astronomers had suspected -- galaxies seem to have some method of 'birth control' that is very effective".........

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September 28, 2006, 10:17 PM CT

Watch How Planets Form

Watch How Planets Form
With the VISIR instrument on ESO's Very Large Telescope, astronomers have mapped the disc around a star more massive than the Sun. The very extended and flared disc most likely contains enough gas and dust to spawn planets. It appears as a precursor of debris discs such as the one around Vega-like stars and thus provides the rare opportunity to witness the conditions prevailing prior to or during planet formation.

"Planets form in massive, gaseous and dusty proto-planetary discs that surround nascent stars. This process must be rather ubiquitous as more than 200 planets have now been found around stars other than the Sun," said Pierre-Olivier Lagage, from CEA Saclay (France) and leader of the team that carried out the observations. "However, very little is known about these discs, especially those around stars more massive than the Sun. Such stars are much more luminous and could have a large influence on their disc, possibly quickly destroying the inner part".

The astronomers used the VISIR instrument [1] on ESO's Very Large Telescope to map in the infrared the disc surrounding the young star HD 97048. With an age of a few million years [2], HD 97048 belongs to the Chameleon I dark cloud, a stellar nursery 600 light-years away. The star is 40 times more luminous than our Sun and is 2.5 times as massive.........

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September 20, 2006, 7:59 PM CT

Launching Of Solar-B

Launching Of Solar-B Image above: An artist concept of Solar-B
Image credit: NASA/GSFC/C. Meane
Solar-B is an international mission to study our nearest star, the sun. To accomplish this, the Solar-B mission includes a suite of three science instruments -- the Solar Optical Telescope, X-ray Telescope and Extreme Ultraviolet Imaging Spectrometer.

Together, these instruments will study the generation, transport, and dissipation of magnetic energy from the photosphere to the corona and will record how energy stored in the sun's magnetic field is released, either gradually or violently, as the field rises into the sun's outer atmosphere.

By studying the sun's magnetic field, researchers hope to shed new light on explosive solar activity that can interfere with satellite communications and electric power transmission grids on Earth and threaten astronauts on the way to or working on the surface of the moon. In particular they want to learn if they can identify the magnetic field configurations that lead to these explosive energy releases and use this information to predict when these events may occur.

Led by the Japan Aerospace Exploration Agency (JAXA), the Solar-B mission is a collaboration between the space agencies of Japan, the United States, the United Kingdom and Europe. NASA helped in the development, funding and assembly of the spacecraft's three science instruments. Solar-B is part of the Solar Terrestrial Probes (STP) Program within the Heliophysics Division of NASA's Science Mission Directorate in Washington. The Solar Terrestrial Probes Program is managed at NASA's Goddard Space Flight Center in Greenbelt, Md. NASA's Marshall Space Flight Center in Huntsville, Ala., managed the development of instrument components provided by NASA, with additional support by academia and industry.........

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September 14, 2006, 6:52 PM CT

Atlantis In Space

Atlantis In Space
Birds don't fly this high. Airplanes don't go this fast. The Statue of Liberty weighs less. No species other than human can even comprehend what is going on, nor could any human just a millennium ago. The launch of a rocket bound for space is an event that inspires awe and challenges description.

Pictured above, the Space Shuttle Atlantis lifted off to visit the International Space Station during the morning of 2006 September 9. From a standing start, the two million kilogram rocket ship left to circle the Earth where the outside air is too thin to breathe and where there is little noticeable onboard gravity. Rockets bound for space are now launched from somewhere on Earth about once a week.........

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September 9, 2006, 7:48 AM CT

One of smallest stellar companions

One of smallest stellar companions This NASA/ESA Hubble Space Telescope image shows one of the smallest objects ever seen around a normal star.
Astronomers using the NASA/ESA Hubble Space Telescope have photographed one of the smallest objects ever seen around a normal star beyond our Sun. Weighing in at 12 times the mass of Jupiter, the object is small enough to be a planet. The riddle is that it is also large enough to be a brown dwarf, a failed star.

The Hubble observation of the diminutive companion to the low-mass red dwarf star CHRX 73 is a dramatic reminder that astronomers do not have a consensus in deciding which objects orbiting other stars are truly planets - even though they have recently provided the definition of 'planet' for objects inside our Solar System.

Kevin Luhman of Penn State University, USA, leader of the international team that found the object (called CHRX 73 'B') is casting his vote for a brown dwarf. "New, more sensitive telescopes are finding smaller and smaller objects of planetary-mass size," said Luhman. "These discoveries have prompted astronomers to ask the question, are planetary-mass companions always planets?".

Some astronomers suggest that an extra-solar object's mass determines whether it is a planet. Luhman and others advocate that an object is only a planet if it formed from the disk of gas and dust that commonly encircles a newborn star. Our Solar System planets formed 4.6 thousand million years ago out of a dust disk around our Sun.........

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September 5, 2006, 9:48 PM CT

New Kind Of Cosmic Explosion

New Kind Of Cosmic Explosion
For the first time a star has been observed in real-time as it goes supernova a mind bogglingly powerful explosion as the star ends its life, the resulting cosmic eruption briefly outshining an entire galaxy. UK scientists, in collaboration with international colleagues, used NASA's Swift satellite and a combination of orbiting and ground-based observatories to catch a supernova in the act of exploding. The results, including an associated and intriguing Gamma Ray Burst [GRB], appear in 31 recent issue of Nature.

The event began on the 18th February, 2006, in a star forming galaxy about 440 million light-years away toward the constellation Aries. At that time it was immediately realised that this was an unusual gamma-ray burst, about 25 times closer and 100 times longer than a typical gamma-ray burst. The burst lasted for almost 40 minutes as opposed to a typical GRB of a few milliseconds to tens of seconds. Because the burst was so long Swift was able to observe the bulk of the explosion with all three of its instruments: the Burst Alert Telescope, which detected the burst and relayed the location to ground observatories within 20 seconds; the X-ray telescope [XRT] and Ultraviolet/Optical Telescope [UVOT], which provide high-resolution imagery and spectra across a broad range of wavelengths.........

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September 4, 2006, 10:11 PM CT

SMART-1 swan song

SMART-1 swan song
Right up to its final orbits, SMART-1 continued delivering valuable data, extending the mission's legacy as a technology and scientific success. Researchers and engineers met today at ESOC to review mission achievements including final AMIE camera images.

At a press event held today at ESA's Spacecraft Operations Centre (ESOC), SMART-1 engineers, operations experts and researchers are presenting data and preliminary results obtained by the spacecraft previous to its impact on the Moon at 07:42 CEST, 3 September 2006.

Perhaps the most sentimental image sequence was taken by AMIE just four days before impact, on 29 August at 21:00 CEST (19:00 UT), when the camera was pointed back towards the Earth to capture, in the best tradition of a number of prior lunar missions, a view of our home planet. The sequence of images is centred over Brazil at approximately 44.9º West and 19.2º South (North is to the left). The Kourou area in French Guiana, from where SMART-1 was launched in 2003, is also visible.

Remarkably, this movie sequence shows the Moon passing in front of the Earth, beautifully underlining the close gravitational relationship between the Earth and its natural satellite.

Final orbits offered new imaging opportunities

During SMART-1's final orbits on 1 and 2 September, the spacecraft was passing at extremely low altitude over the Moon's surface, which was in darkness, prompting researchers to take advantage of this unique observational situation by pointing the AMIE camera laterally toward the Moon's limb (horizon). The camera gathered images of the thin dust envelope surrounding the Moon, which will be analysed by researchers in the future.........

Posted by: Edwin      Permalink         Source


September 3, 2006, 7:04 AM CT

Atlantis would be Launched on Sept 6

Atlantis would be Launched on Sept 6 Space Shuttle Atlantis, September 8, 2000
John F. Kennedy Space Center, State of Florida, USA
The six Atlantis crew members flew Saturday morning from their home base in Houston to the Kennedy Space Center in Florida, where they will begin final launch preparations for mission STS-115.

The countdown officially begins at 8 a.m. Sunday, at the T-43 hour mark, which includes over 30 hours of built-in hold time prior to a targeted 12:29 p.m. EDT launch on Wednesday. The launch time is the middle point in the launch window that extends for 10 minutes.

Atlantis' Crew and Mission

The STS-115 crew consists of Commander Brent W. Jett Jr., Pilot Christopher J. Ferguson and Mission Specialists Heidemarie M. Stefanyshyn-Piper, Joseph R. Tanner, Daniel C. Burbank and Steven G. MacLean, who represents the Canadian Space Agency.

With this mission, NASA is ready to get back to building the International Space Station, marking the first time in almost four years that a space station component has been added to the orbiting outpost. That also means the shuttle program is coming up on some of the most challenging space missions ever.

During their three spacewalks, crew members of Atlantis will install the P3/P4 integrated truss and a second set of solar arrays on the space station, doubling the station's current ability to generate power from sunlight and adding 17.5 tons to its mass.........

Posted by: Edwin      Permalink         Source


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