Reblogged from physorg.com August 19th, 2009 at 5:58 pm Notes #astrophysics #astronomy #space
The dense star cluster RCW 38 glistens about 5500 light years away in the direction of the constellation Vela (the Sails). Like the Orion Nebula Cluster, RCW 38 is an “embedded cluster”, in that the nascent cloud of dust and gas still envelops its stars. Astronomers have determined that most stars, including the low mass, reddish ones that outnumber all others in the Universe, originate in these matter-rich locations. Accordingly, embedded clusters provide scientists with a living laboratory in which to explore the mechanisms of star and planetary formation.
“By looking at star clusters like RCW 38, we can learn a great deal about the origins of our Solar System and others, as well as those stars and planets that have yet to come”…
Using the NACO adaptive optics instrument on ESO’s Very Large Telescope the astronomers obtained the sharpest image yet of RCW 38. They focused on a small area in the centre of the cluster that surrounds the massive star IRS2, which glows in the searing, white-blue range, the hottest surface colour and temperatures possible for stars. These dramatic observations revealed that IRS2 is actually not one, but two stars — a binary system consisting of twin scorching stars, separated by about 500 times the Earth-Sun distance.
This swirling ball of pink and blue gas is the Trifid Nebula, a rare combination of three different kinds of interstellar clouds located 5,500 light years away in the constellation of Sagittarius.
Captured by the European Southern Observatory’s 2.2-meter telescope at the La Silla Observatory in Chile, this image shows off the three distinct types of nebulae found in the Trifid. The bluish patch in the upper left is known as a reflection nebula because it scatters light from nearby stars. The largest of these stars, which were all born in the Trifid, can be seen shining in the center of the reflection nebula. It radiates hot blue light in the visible spectrum and gives the cloud a bluish tinge.
The bright pink circle in the lower half of the photo is an emission nebula, which glows red because it contains a core of hydrogen gas heated by hundreds of super-hot new stars. At the bottom of the emission nebula, a finger-shaped projection of gas points up at the Trifid’s central star. Known as an evaporating gaseous globule, or EGG, this dense blob of gas is a birthplace for new stars.
The Trifid’s third kind of nebula can be seen in the dark stripes that criss-cross the rest of the image. Called dark nebulae because of their light-obscuring properties, these clouds of gas and dust contain the remnants of previous star births. As higher pressure and temperatures build up inside the streaks of gas, nuclear fusion will lead to the formation of yet more stars.
Photo via ESO.Reblogged from Wired August 28th, 2009 at 1:51 am 3 notes #space #astronomy #nebula #stars #astrophysics
Magnetic reconnection could be the Universe’s favorite way to make things explode. It operates anywhere magnetic fields pervade space—which is to say almost everywhere. On the sun magnetic reconnection causes solar flares as powerful as a billion atomic bombs. In Earth’s atmosphere, it fuels magnetic storms and auroras. In laboratories, it can cause big problems in fusion reactors. It’s ubiquitous.
Someone stabbed the sun with a giant bowling pin!September 1st, 2009 at 9:48 pm Notes #space #physics #sun #astrophysics
Reblogged from unknownskywalker February 15th, 2010 at 11:38 pm 7 notes #space #science #astrophysics
Superfast protons sometimes slam into the Earth from space flying at close to the speed of light. Where these particles, called cosmic rays, come from has been a scientific mystery. But new evidence helps confirm the leading explanation – that they originate in the distant remnants of dead stars.
Such a so called supernova remnants contains shells of gas that were ejected from a star before it collapsed in a supernova explosion. They harbor strong magnetic fields that are thought to behave like giant particle accelerators, speeding up particles that become cosmic rays.
Turning Planetary Theory Upside DownReblogged from unknownskywalker April 13th, 2010 at 11:06 pm 134 notes #space #science #astrophysics
Scientists have announced the discovery of nine new transiting exoplanets. When these new results were combined with earlier observations of transiting exoplanets astronomers were surprised to find that six out of a larger sample of 27 were found to be orbiting in the opposite direction to the rotation of their host star — the exact reverse of what is seen in our own Solar System.
The new discoveries provide an unexpected and serious challenge to current theories of planet formation. They also suggest that systems with exoplanets of the type known as Hot Jupiters are unlikely to contain Earth-like planets.
Planets are thought to form in the disc of gas and dust (proto-planetary disc) rotating around a young star in the same direction as the star itself, in more or less the same plane. Since Hot Jupiters have cores made of rock and ice particles found in the outer reaches of planetary systems, they form far from their star, and then migrate inwards to orbit it much closer via gravitational interactions with the proto-planetary disc.
A theory suggests that the proximity of hot Jupiters to their stars is not due to interactions with the dust disc at all, but to a slower evolution process involving a gravitational war with more distant planetary or stellar companions over hundreds of millions of years. After these disturbances have bounced a giant exoplanet into a tilted and elongated orbit, it would suffer tidal friction, losing energy every time it swung close to the star. It would eventually become parked in a near circular, but randomly tilted, orbit close to the star. A dramatic side-effect of this process is that it would wipe out any other smaller Earth-like planet in these systems.
Image: Artist’s impression of the planet WASP 8b transiting its parent star. Credit: ESOSource: ESO, Royal Astronomical Society
Einstein’s Theory Fights off ChallengersReblogged from unknownskywalker April 15th, 2010 at 11:33 pm 37 notes #space #science #astrophysics #relativity #Einstein
Two different teams have put Einstein’s General Theory of Relativity to the test like never before, showing that it’s still the best game in town. Each team of scientists took advantage of extensive Chandra X-ray observations of galaxy clusters, the largest objects in the Universe bound together by gravity.
This composite image of the galaxy cluster Abell 3376 shows X-ray data from the Chandra X-ray Observatory and the ROSAT telescope in gold, an optical image from the Digitized Sky Survey in red, green and blue, and a radio image from the VLA in blue. The “bullet-like” appearance of the X-ray data is caused by a merger, as material flows into the galaxy cluster from the right side. The giant radio arcs on the left side of the image may be caused by shock waves generated by this merger.
The growth of galaxy clusters like Abell 3376 is influenced by the expansion rate of the universe - controlled by the effects of dark matter and dark energy - and by the properties of gravity over large scales.
In these studies, scientists used data from galaxy clusters and compared them with other theoretical models, studies of supernovas, and how rapidly galaxy clusters have grown over cosmic time. Einstein succeeds in showing that gravity is not different from General Relativity on scales larger than 130 million light years (the strongest ever constraint set on such large distance scales), and in calculating how many massive clusters have formed under gravity’s pull over the last five billion years.
Excitingly and reassuringly, these results are the most robust consistency test of General Relativity yet carried out on cosmological scales.
Reblogged from unknownskywalker June 18th, 2010 at 11:05 am 9 notes #space #astrophysics #cosmology
Astronomers Witness a Star Being Born
Astronomers have glimpsed what could be the youngest known star at the very moment it is being born. Not yet fully developed into a true star, the object is in the earliest stages of star formation and has just begun pulling in matter from a surrounding envelope of gas and dust.
The object was found using the Submillimeter Array in Hawaii and the Spitzer Space Telescope. Known as L1448-IRS2E, it’s located in the Perseus star-forming region, about 800 light years away within our Milky Way galaxy.
Stars form out of large, cold, dense regions of gas and dust called molecular clouds, which exist throughout the galaxy. Astronomers think L1448-IRS2E is in between the prestellar phase, when a particularly dense region of a molecular cloud first begins to clump together, and the protostar phase, when gravity has pulled enough material together to form a dense, hot core out of the surrounding envelope.
It’s very difficult to detect objects in this phase of star formation, because they are very short-lived and they emit very little light. The team detected the faint light emitted by the dust surrounding the object.
Most protostars are between 1 to 10 times as luminous as the Sun, with large dust envelopes that glow at infrared wavelengths. Because L1448-IRS2E is less than one tenth as luminous as the Sun, the team believes the object is too dim to be considered a true protostar.
Yet they also discovered that the object is ejecting streams of high-velocity gas from its center, confirming that some sort of preliminary mass has already formed and the object has developed beyond the prestellar phase. This kind of outflow is seen in protostars (as a result of the magnetic field surrounding the forming star), but has not been seen at such an early stage until now.
Stars are defined by their mass, but we still don’t know at what stage of the formation process a star acquires most of its mass. The team hopes to use the new Herchel space telescope to look for more of these objects caught between the earliest stages of star formation so they can better understand how stars grow and evolve.
Image: An image made with the Infrared Astronomical Satellite (IRAS) showing a very large field of the sky (some 100 x 100 square-degrees) including the Perseus molecular cloud complex (upper right), the Taurus-Auriga molecular cloud complex (upper left), and the Orion star forming region (lower center). [+]