R Sculptoris


This image, which was taken by the Very Large Telescope at the European Southern Observatory, shows an extremely small section of the sky: approximately 20×20 milliarcseconds. For comparison, Jupiter as seen from Earth has an angular size of roughly 40 arcseconds. The ghostly image is of a distant, pulsating red giant star known as R Sculptoris, which is 1200 light-years away in the constellation of Sculptor. It’s a carbon-rich asymptotic giant branch star that is nearing the end of its life. As the end comes, low- and intermediate-mass stars cool off, create extended atmospheres, and lose a lot of their mass—before becoming spectacular planetary nebulae.

One odd feature of R Sculptoris is its dominant bright spot which seems to be two or three times brighter than the rest of the star. Astronomers speculate that R Sculptoris is surrounded by giant “clumps” of stellar dust that are peeling away from the shedding star. This bright spot is probably a region around the star with less dust, allowing more light to escape.

Image Credit: ESO

Uranus and Four of Its Satellites


This infrared image of the planet Uranus was captured by the European Southern Observatory’s Very Large Telescope during the planet’s 2008 equinox. Every 42 years, the ring (and satellites) plane of Uranus line up with the Sun causing them to appear on edge from Earth’s point of view. A one minute exposure time was used, the maximum allowable to prevent the moving satellites from appearing as streaks. The IR filter used matches the absorption bands of the methane in the atmosphere of Uranus, making the relatively bright planet (almost) completely disappear. That permits the otherwise invisible rings and small satellites of Uranus to be detected instead of being lost in the glare of the planet. The bright spots on each side of Uranus are Miranda (~470 km diameter) and Ariel (~1100 km diameter). Two much smaller satellites can be seen just above the ring plane,to the left of the planet. Puck (~150 km diameter) is closer to the Planet than Portia (~100 km diameter).

Image Credit: ESO

Asteroids!


These detailed images were taken by ESO’s Very Large Telescope at the Paranal Observatory in Chile. Clockwise from top left, the asteroids shown here are 29 Amphitrite, 324 Bamberga, 2 Pallas, and 89 Julia.

2 Pallas was named after the Greek goddess Pallas Athena and is about 510 km wide. It’s the third largest asteroid in the main belt and one of the biggest asteroids in the entire Solar System. It contains about 7% of the mass of the entire asteroid belt andt was once classified as a planet.

89 Julia is about one-third the size of Pallas. It’s classified as a stony or S-type asteroid, as is 29 Amphitrite. 324 Bamberga, one of the largest carbonaceous or C-type asteroids in the asteroid belt. C-type asteroids may actually be bodies from the outer Solar System which followed the migration of the giant planets inward.

In total, the asteroid belt contains just 4% of the mass of the Moon, with about half of this mass contained in the four largest: the dwarf planet Ceres, 4 Vesta, 2 Pallas, and 10 Hygiea.

Image Credit: ESO