This artist's concept shows a debris disk that has been observed around an unusual class of interacting binary stars. The type of cataclysmic variable system being studied consists of a highly magnetic white dwarf star (a 'dead' remnant star formed from the core of a star like our Sun when it exhausts the available fuel to support nuclear fusion) and a very low-mass, cool object similar to a brown dwarf. The two objects orbit so closely that they make a complete revolution about each other in only 80-90 minutes. P. Marenfeld and NOAO/AURA/NSF
This artist's concept shows a brown dwarf surrounded by a swirling disk of planet-building dust. NASA's Spitzer Space Telescope spotted such a disk around a surprisingly low-mass brown dwarf, or 'failed star.' The brown dwarf, called OTS 44, is only 15 times the size of Jupiter, making it the smallest brown dwarf known to host a planet-forming, or protoplanetary disk. NASA/JPL-Caltech/T. Pyle (SSC)
This image presents a greatly simplified, schematic view of a pair of brown dwarfs orbiting each other. The binary dwarf system lies in the Orion nebula. The binary pair is too close to be resolved with present-day telescopes. This is an artistic oblique view of the system. In reality, the orbital plane is tilted edge-on to Earth such that the stars are seen eclipsing each other. Eclipses can be frequently observed because the dwarfs complete an orbit approximately once every ten days. NASA
This is an artist's concept of the red dwarf star CHXR 73 (upper l.) and its companion CHXR 73 B in the foreground (lower r.) weighing in at 12 Jupiter masses. CHXR 73 B is one of the smallest companion objects ever seen around a normal star beyond our Sun. Estimated to be 12 times the mass of Jupiter, the object is small enough to be a planet, but also large enough to be a brown dwarf, a failed star. NASA
This NASA Hubble Space Telescope image of planetary nebula NGC 7027 shows remarkable new details of the process by which a star like the Sun dies. New features include: faint, blue, concentric shells surrounding the nebula; an extensive network of red dust clouds throughout the bright inner region; and the hot central white dwarf, visible as a white dot at the center. The nebula is a record of the star's final death throes. NASA
The nearby dwarf galaxy NGC 1569 is a hotbed of vigorous star birth activity, which blows huge bubbles that riddle the galaxy's main body. The image was taken by a camera on Hubble designed and built by the Jet Propulsion Laboratory. NASA/JPL/Hubble
This artist's illustration shows three steps in the merger of a pair of white dwarf stars. The illustration depicts how planets may form around massive white dwarfs. At least half of the stars in our Milky Way galaxy are double star systems. During their evolution such systems may undergo a phase in which the cores of the two stars revolve inside a tenuous common envelope. The end product of such a phase can be a close pair of very compact objects known as white dwarfs. NASA
This is an artist's concept of a gas giant planet orbiting the cool, red dwarf star Gliese 876, located 15 light-years away in the autumn constellation Aquarius. The planet was discovered in 1998. But new Hubble Space Telescope measurements of the star's wobble, caused by the gravitational tug of the planet, firmly establish the planet's mass as being no more than approximately twice that of Jupiter's. NASA
This composite image shows Z Camelopardalis, or Z Cam, a double-star system featuring a collapsed, dead star, called a white dwarf, and a companion star, as well as a ghostly shell around the system. The massive shell provides evidence of lingering material ejected during and swept up by a powerful classical nova explosion that occurred probably a few thousand years ago. NASA/JPL-Caltech
This Hubble Space Telescope image shows Sirius A, the brightest star in our nighttime sky, along with its faint, tiny stellar companion, Sirius B, a white dwarf. Astronomers overexposed the image of Sirius A (at center) so that the dim Sirius B (tiny dot at lower left) could be seen. The two stars revolve around each other every 50 years. NASA
This ultraviolet image shows the planetary nebula NGC 7293 also known as the Helix Nebula. It is the nearest example of what happens to a star, like our own Sun, as it approaches the end of its life when it runs out of fuel, expels gas outward and evolves into a much hotter, smaller and denser white dwarf star. NASA/JPL-Caltech/SSC
This artist's concept illustrates a comet being torn to shreds around a dead star, or white dwarf, called G29-38. NASA's Spitzer Space Telescope observed a cloud of dust around this white dwarf that may have been generated from this type of comet disruption. The findings suggest that a host of other comet survivors may still orbit in this long-dead solar system. NASA/JPL-Caltech/T. Pyle (SSC)
This figure shows an artist's rendition comparing brown dwarfs to stars and planets. All objects are plotted to the same scale. On the far left is the limb of the Sun. To its right is shown a very low mass star (a so-called 'late-M dwarf'), a couple of brown dwarfs (a hotter 'L dwarf' and a cooler 'T dwarf'), and the planet Jupiter. NASA/IPAC/R. Hurt
Chilean authorities had issued an orange alert on Monday because of increased activity at the volcano.
ByEva Vergara and Gabriela Ulloa, Associated Press
One of South America's most active volcanoes erupted early Tuesday in southern Chile, spewing heavy smoke into the air as lava surged down its slopes, prompting authorities to evacuate thousands of people.