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.
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).
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.
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.
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.
During Rosetta's recent Mars swingby, the OSIRIS cameras captured a series of images of Mars and of Phobos transiting Mars' disk. The OSIRIS team have produced a cool animated sequence and a 3D view of the Red Planet.
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.
Scientists were startled when they discovered in 2004 that the center of our galaxy is emitting gamma rays with energies in the tens of trillions of electronvolts.
NASA's Spitzer Space Telescope has captured for the first time enough light from planets outside our solar system, known as exoplanets, to identify signatures of molecules in their atmospheres. The landmark achievement is a significant step toward being able to detect possible life on rocky exoplanets and comes years before astronomers had anticipated.
The ESO Very Large Telescope Interferometer, which allows astronomers to scrutinise objects with a precision equivalent to that of a 130-m telescope, is proving itself an unequalled success every day. One of the latest instruments installed, AMBER, has led to a flurry of scientific results, an anthology of which is being published this week as special features in the research journal Astronomy & Astrophysics.
Integral's latest survey of the gamma-ray universe continues to change the way astronomers think of the high-energy cosmos. With over seventy percent of the sky now observed by Integral, astronomers have been able to construct the largest catalogue yet of individual gamma-ray-emitting celestial objects. And there is no end in sight for the discoveries.
As NASA develops its next "flagship" mission to the outer solar system, Jupiter's enigmatic moon Europa should be the target, says Arizona State University professor Ronald Greeley. Although Europa lies five times farther from the Sun than Earth, he notes it may offer a home for life.
Greeley, a Regents' Professor, heads the Planetary Geology Group in ASU's School of Earth and Space Exploration. He is presenting the Europa proposal today (Feb. 18) at the annual meeting of the American Association for the Advancement of Science in San Francisco.
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.
Liquid or gas flowed through cracks penetrating underground rock on ancient Mars, according to a report based on some of the first observations by NASA's Mars Reconnaissance Orbiter. These fluids may have produced conditions to support possible habitats for microbial life.
This NASA Hubble Space Telescope image shows the colorful "last hurrah" of a star like our Sun. The star is ending its life by casting off its outer layers of gas, which formed a cocoon around the star's remaining core. Ultraviolet light from the dying star then makes the material glow. The burned-out star, called a white dwarf, appears as a white dot in the center. Our Milky Way Galaxy is littered with these stellar relics, called planetary nebulae. Hubble's Wide Field Planetary Camera 2 captured this image of planetary nebula NGC 2440 on Feb.