Brown dwarfs, "failed stars", are a class of objects that represent the missing link between the lowest-mass stars and the gas-giant planets, such as Jupiter and Saturn. Brown dwarfs are the faintest and coolest objects that can be directly observed outside the solar system, emitting as little as 1/300,000th of the energy of the sun and having surface temperatures around 800° F - that's the temperature of a pizza oven and more than 9,000° F cooler than the surface of the sun.
Astronomers have used ultrasharp images obtained with the Keck Telescope and Hubble Space Telescope to determine for the first time the masses of the coldest class brown dwarfs. With masses as light as 3 percent the mass of the sun, these are the lowest mass free-floating objects ever weighed outside the solar system. The observations are a major step in testing the theoretical predictions of objects that cannot generate their own internal energy, both brown dwarfs and gas-giant planets. The new findings, which are being presented in a press conference today at the American Astronomical Society meeting in St. Louis, show that the predictions may have some problems.
"The universe is a big place, and weird things can happen. I was flipping through archived Spitzer data of the object, and that's when I noticed it was surrounded by a ring we'd never seen before, "said Stephanie Wachter of NASA's Spitzer Science Center at the California Institute of Technology about a mysterious infrared ring a dead star that displays a magnetic field trillions of times more intense than Earth's.
NASA's Spitzer Space Telescope detected the ring around magnetar SGR 1900+14 at two narrow infrared frequencies in 2005 and 2007. The ringed magnetar is of a type called a soft gamma repeater (SGR) because it repeatedly emits bursts of gamma rays.
ESO's VLT has allowed astronomers to determine that WOH G64, a red supergiant star almost 2,000 times as large as our Sun located 163,000 light-years away in the Large Magellanic Cloud, weighs almost half of what was previously thought, thereby solving the mystery of its existence.
The behemoth star is found to be surrounded by a massive and thick torus of gas and dust, and is most likely experiencing unstable, violent mass loss.
"Previous estimates gave an initial mass of 40 times the mass of the Sun to WOH G64. But this was a real problem as it was way too cold, compared to what theoretical models predict for such a massive star. Its existence couldn't be explained," says Keiichi Ohnaka, who led the work on this object.
NASA's Phoenix spacecraft landed in the northern polar region of Mars Sunday to begin three months of examining a site chosen for its likelihood of having frozen water within reach of the lander's robotic arm.
Radio signals received at 4:53:44 p.m. Pacific Time (7:53:44 p.m. Eastern Time) confirmed the Phoenix Mars Lander had survived its difficult final descent and touchdown 15 minutes earlier. The signals took that long to travel from Mars to Earth at the speed of light.
Mission team members at NASA's Jet Propulsion Laboratory, Pasadena, Calif.; Lockheed Martin Space Systems, Denver; and the University of Arizona, Tucson, cheered confirmation of the landing and eagerly awaited further information from Phoenix later Sunday night.
Two new exoplanets mean that the COROT mission(1) has now found a total of four new exoplanets in its 510 day journey. COROT started observations of its sixth star field at the beginning of May and, during this observation phase which will last 5 months, will simultaneously observe 12,000 stars.
The two new planets are gas giants of the hot Jupiter type, which orbit very close to their parent star and tend to have extensive atmospheres because heat from the nearby star gives them energy to expand. But an oddity dubbed ‘COROT-exo-3b’ has raised particular interest among astronomers. It appears to be something between a brown dwarf, a sub-stellar object without nuclear fusion at its core but with some stellar characteristics, and a planet. Its radius is too small for it to be a super-planet.
Astronomers have seen the aftermath of spectacular stellar explosions known as supernovae before, but until now no one has witnessed a star dying in real time. While looking at another object in the spiral galaxy NGC 2770, using NASA’s orbiting Swift telescope, Carnegie-Princeton fellows* Alicia Soderberg and Edo Berger detected an extremely luminous blast of X-rays released by a supernova explosion.
They alerted 8 other orbiting and on-ground telescopes to turn their eyes on this first-of-its-kind event.
“We were in the right place, at the right time, with the right telescope on January 9th and witnessed history,” remarked Soderberg. “We were looking at another, older supernova in the galaxy, when the one now known as SN 2008D went off. We would have missed it if it weren’t for Swift’s real-time capabilities, wide field of view, and numerous instruments.”
On April 25, NASA’s Swift satellite picked up the brightest flare ever seen from a normal star other than our Sun. The flare, an explosive release of energy from a star, packed the power of thousands of solar flares. It would have been visible to the naked eye if the star had been easily observable in the night sky at the time.
The star, known as EV Lacertae, isn’t much to write home about. It’s a run-of-the-mill red dwarf, by far the most common type of star in the universe. It shines with only one percent of the Sun’s light, and contains only a third of the Sun’s mass. At a distance of only 16 light-years, EV Lacertae is one of our closest stellar neighbors. But with its feeble light output, its faint magnitude-10 glow is far below naked-eye visibility.
An obese oddball of a star has left astronomers wondering how it could have formed.
Found with the Arecibo radio telescope in Puerto Rico, the star is a pulsar – a compact, rapidly spinning star – called J1903+0327. It lies 20,000 light-years away spinning at a rate of 465 revolutions per second – the fifth fastest-spinning pulsar known in our Galaxy.
Astronomers believe such super-fast pulsars started life as the more common, sedate pulsars that spin only a few times a second, but were later ’reborn‘ in their present hyperactive state. This re-birthing or recycling can take place, astronomers think, if the pulsar has a nearby companion that it orbits. At a certain point in its life cycle, the companion pours its own matter onto the pulsar and this extra material ‘spins-up‘ the pulsar.
Hydroxyl is made up of a hydrogen and oxygen atom each. It has been found on another planet for the first time - in the upper reaches of the atmosphere of Venus, some 100 km above the surface - by Venus Express’s Visible and Infrared Thermal Imaging Spectrometer, VIRTIS. It is thought to be important for any planet’s atmosphere because it is highly reactive. On Earth it has a key role in purging pollutants from the atmosphere.
The OH “radical” is a very special and reactive molecule, which is unusual in conventional chemistry because of its reactivity. This detection gives scientists an important new tool to unlock the workings of Venus’s dense atmosphere.
The elusive molecule was detected by turning the spacecraft away from the planet and looking along the faintly visible layer of atmosphere surrounding the planet’s disc. The instrument detected the hydroxyl molecules by measuring the amount of infrared light that they give off.
New observations from NASA's Mars Reconnaissance Orbiter indicate that the crust and upper mantle of Mars are stiffer and colder than previously thought.
The findings suggest any liquid water that might exist below the planet's surface and any possible organisms living in that water, would be located deeper than scientists had suspected.
"We found that the rocky surface of Mars is not bending under the load of the north polar ice cap," said Roger Phillips of the Southwest Research Institute in Boulder, Colo. Phillips is the lead author of a new report appearing in this week's online version of Science. "This implies that the planet's interior is more rigid, and thus colder, than we thought before."