Several times a week, astronomers detect the violent death cry of a massive star -- an extraordinarily energetic release of gamma rays that takes place in just a matter of seconds to minutes, called a gamma-ray burst (GRB). The GRB's ejecta, which is thought to be beamed in narrow jets, slams into interstellar gas at near light speed. This violent collision shocks the material and produces a bright afterglow that can radiate brightly at X-ray and other wavelengths for several days, or even a few weeks.
For the very first time, astronomers have witnessed the speeding up of an asteroid's rotation, and have shown that it is due to a theoretical effect predicted but never seen before. The international team of scientists used an armada of telescopes to discover that the asteroid's rotation period currently decreases by 1 millisecond every year, as a consequence of the heating of the asteroid's surface by the Sun.
Imagine two stars with winds so powerful that they eject an Earth's worth of material roughly once every month. Next, imagine those two winds colliding head-on. Such titanic collisions produce multimillion-degree gas, which radiates brilliantly in X-rays. Astronomers have conclusively identified the X-rays from about two-dozen of these systems in our Milky Way. But they have never seen one outside our galaxy — until now.
Thanks to the European Space Agency's XMM-Newton X-ray observatory, with help from NASA's Chandra X-ray Observatory, an international team led by Dr Yaël Nazé of the Université de Liège in Belgium has found such a system in a nearby galaxy. This galaxy, the Small Magellanic Cloud, orbits the Milky Way and is located about 170 000 light-years from Earth.
A team of European astronomers offer new evidence that high-mass stars could form in a similar way to low-mass stars, that is, from accretion of gas and dust through a disk surrounding the forming star. Their article, published in Astronomy & Astrophysics, reports the discovery of a jet of molecular hydrogen arising from a forming high-mass star located in the Omega nebula (M17). This detection confirms the hypothesis based on their earlier discovery that this forming high-mass star is surrounded by a large accretion disk.
Near-infrared image of the M17 silhouette disk, discovered in 2004.
Several hundred images taken with NASA's Hubble Space Telescope have been woven together into a rich tapestry of at least 50,000 galaxies. The Hubble view is yielding new clues about the universe's youth, from its "pre-teen" years to young adulthood.
The snowstorm of galaxies in the Hubble panorama does not appear evenly spread out. Some galaxies seem to be grouped together. Others are scattered through space. This uneven distribution of galaxies traces the concentration of dark matter, an invisible web-like structure stretching throughout space.
Tonight there will be a total lunar eclipse. The partial eclipse will begin at 21:30:04 UT and end 3½ hours later at 01:11:46 UT. The total eclipse lasts for about one hour; it begins at 22:43:49 UT and ends at 23:58:01 UT. The moment of greatest eclipse is at 23:20:56 UT on March 3. The eclipse will be visible over Europe, Africa, and the western part of Asia. Unfortunately, we over here in America will see only a part of it and only on the East coast. For a more detailed schedule, click here.
By analyzing the COSMOS field, the largest field of galaxies ever observed with the Hubble space telescope, an international team of scientists led by researchers from the California Institute of Technology (United States) and researchers from the associated laboratories of the CNRS and the CEA , made the first three-dimensional map of dark matter in the Universe using gravitational lensing effects. This historic first seems to confirm the standard theories on the formation of the large structures of the Universe. This study was presented in the January 7, 2007 issue of the journal "Nature."
Three-dimensional map of black matter in the COSMOS field. © ESA/NASA
The changing Larsen-B Ice Shelf captured by Envisat on 22 February 2007 with its Advanced Synthetic Aperture Radar (ASAR). The Larsen Ice Shelf is a series of three shelves – A (the smallest), B and C (the largest) – that extend from north to south along the eastern side of the Antarctic Peninsula. Changes in ice shelves are believed to be indicators of climate change, as evidence suggests high latitudes experience the greatest atmospheric warming. Credits: ESA
There are many galaxies of different shapes and sizes around us today. Roughly half are gas-poor elliptical-shaped galaxies with little new star formation activity, and half are gas-rich spiral and irregular galaxies with high star formation activity. Observations have shown that gas-poor galaxies are most often found near the centre of crowded galaxy clusters, whereas spirals spend most of their lifetime in solitude.
An extended view of the Hubble image also shows the gravitational lensing effect -- an optical illusion -- caused by the cluster's gravitational tidal forces of the cluster and "ram pressure stripping" by the hot gas.
On February 28, 2007, NASA's New Horizons spacecraft made its closest approach to Jupiter on its ultimate journey to Pluto. This flyby gave scientists a unique opportunity to study Jupiter using the package of instruments available on New Horizons, while coordinating observations from both space- and ground-based telescopes including NASA's Chandra X-ray Observatory.
In preparation for New Horizon's approach of Jupiter, Chandra took 5-hour exposures of Jupiter on Feb. 8, 10 and 24. In this new composite image, data from those separate Chandra's observations were combined, and then superimposed on the latest image of Jupiter from the Hubble Space Telescope.