Category Astronomy/Space

Same sequence as above, with indication of dates and location of the morphological changes. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

In the months leading to the perihelion of Comet 67P/Churyumov-Gerasimenko, Rosetta scientists have been witnessing dramatic and rapid surface changes on the Imhotep region. Since arriving at Comet 67P/C-G in August 2014, Rosetta has been witnessing an increase in the activity of the comet, warmed by the ever-closer Sun. A general increase in the outflow of gas and dust has been punctuated by the emergence of jets and dramatic rapid outbursts in the weeks around perihelion, the closest point to the Sun on the comet’s orbit, which occurred on 13 August 2015.

But in June 2015, just 2 months before perihelion, Rosetta scient...

At left is the galaxy J0702+5002, which the researchers concluded is not an X-shaped galaxy whose form is caused by a merger. At right is the galaxy J1043+3131, which is a “true” candidate for a merged system. Credit: Roberts, et al., NRAO/AUI/NSF

Astronomers analyzing new images of ‘X-shaped galaxies’ conclude that their peculiar shape is less-commonly caused by mergers than was thought. This result could lower the level of gravitational waves coming from such galaxies.

Massive galaxies harbor black holes with millions of times more mass than our Sun at their centers. When 2 such galaxies collide, their supermassive black holes join in a close orbital dance that ultimately results in the pair combining...

This image, taken with the European Southern Observatory’s Very Large Telescope, shows the central region of galaxy NGC1313. This galaxy is home to the ultraluminous X-ray source NCG1313X-1, which astronomers have now determined to be an intermediate-mass black hole candidate. NGC1313 is 50,000 light-years across and lies about 14 million light-years from the Milky Way in the southern constellation Reticulum. Credit: ESO

Nearly all black holes come in 1 of 2 sizes: stellar mass black holes that weigh up to a few dozen times the mass of our sun or supermassive black holes ranging from a million to several billion times the sun’s mass...

Credit: ESA/Hubble & NASA, Acknowledgement: Judy Schmidt

It is known today that merging galaxies play a large role in the evolution of galaxies and the formation of elliptical galaxies in particular. However there are only a few merging systems close enough to be observed in depth. The pair of interacting galaxies seen here—known as NGC 3921 — is one of these systems.

NGC 3921—found in the constellation of Ursa Major (The Great Bear)—is an interacting pair of disk galaxies in the late stages of its merger. Observations show that both of the galaxies involved were about the same mass and collided about 700 million years ago. You can see clearly in this image the disturbed morphology, tails and loops characteristic of a post-merger.
The clash of galaxies caused a rush of star formati...