Category Astronomy/Space

A close-up of the canyons on Charon, Pluto’s big moon, taken by New Horizons during its close approach to the Pluto system last July. Multiple views taken by New Horizons as it passed by Charon allow stereo measurements of topography, shown in the color-coded version of the image. The scale bar indicates relative elevation. Credits: NASA/JHUAPL/SwRI

Pluto’s largest moon may have gotten too big for its own skin. Images from NASA’s New Horizons mission suggest Pluto’s moon Charon once had a subsurface ocean that has long since frozen and expanded, pushing outward and causing the moon’s surface to stretch and fracture on a massive scale...

The actual mechanism causing asteroids to disrupt is still unknown but some obvious scenarios such as tidal forces caused by the Sun and direct sublimation of silicates have been ruled out. One of the remaining scenarios is that volatiles inside the asteroid sublimate at moderate temperatures and create enough pressure to blow up the body. A similar process on a smaller scale called spalling can also break up surface rocks. Credit: Lauri Voutilainen

For 2 decades it was thought that most near-Earth objects (NEOs)—asteroids and comets that may pose a hazard to life on Earth—end their existence in a dramatic final plunge into the Sun. A new study finds instead that most of those objects are destroyed much farther from the Sun than previously thought...

This is an artist’s impression of the clash of powerful stellar winds. Credit: NASA/C. Reed

The new source confirmed that binary systems with strong colliding stellar winds comprise a separate new population of high-energy gamma-ray sources. Massive binary star systems with highly luminous and hot Wolf-Rayet stars and massive (tens solar masses) OB companion generate strong stellar winds. Its percussion may lead to producing a fierce photon flux with an energetic potential of >100 MEV, when a distance separating stars is relatively short. That phenomenon was considered a possible source of gamma-radiation for a long while.

Though such radiation was detected only once, with the famous Eta Carinae when one of its stars underwebt an explosion and for some time was the most luminous star in th...

10 arcmin x 10 arcmin field showing luminosity (top) and temperature (bottom) maps of Abell 3888 before (left) and after (right) point source removal. The color scale in the luminosity map is set so that white corresponds to the maximum cluster flux. The point source is 100 times brighter than this level. The scale in the temperature map ranges from 2 to 10 keV. Credit: Andersson, K. et al., 2009

Studying substructures of galaxy clusters can reveal important information about the morphology and evolution processes of these gravity-bound groups of galaxies. Optical spectroscopy helps unravel the history of large-scale structure formation in the universe...