Partly Cloudy, For Now

The Dark Cloud Lupus 4Lupus 4, a spider-shaped blob of gas and dust, blots out background stars like a dark cloud on a moonless night. Although dark and gloomy for now, dense pockets of material within such clouds are where new stars form and where they will later burst into radiant life. Lupus 4 is about 400 light-years away, straddling the constellations of Lupus (The Wolf) and Norma (The Carpenter’s Square).

Image Credit: ESO

Visions of Future Past

ngc2207Over next couple of billion years, these two spiral galaxies will end up in a complete galactic merger—the two galaxies will become a single, larger one. They’re about 150 million light-years away in the constellation of Canis Major (the Great Dog), so what we can see now is what was happening 150 million years ago.

The gravitational attraction of NGC 2207, the larger of the pair, is already stirring things up throughout its smaller partner, distorting IC 2163’s shape and throwing stars and gas into long streamers that extend over 100,000 light-years. However, most of the space between stars in a galaxy is empty. When these galaxies collide, almost none of the stars in them will crash into another star.

This 150 million old image is a vision of the Milky Way’s future. About the time NGC 2207 and IC 2163 have finished their merger, the Milky Way will begin colliding with the Andromeda Galaxy.

Image Credit: ESO


The halo of galaxy Messier 87The giant elliptical galaxy Messier 87 is surrounded by a huge halo. An increase in brightness in the top-right part of this halo and the motion of planetary nebulae in the galaxy are the last remaining signs of a medium-sized galaxy that collided with M87.

This wide field image also contains many other galaxies forming the Virgo Cluster, of which Messier 87 is the largest member. The two galaxies at the edge of the top right of the frame are nicknamed “the Eyes.”

Image Credit: ESO

A Different Kind of Sunspot

Here’s the European Southern Observatory’s description of this animation—

Spots on extreme horizontal branch stars (right) appear to be quite different from the dark sunspots on our own Sun (left), but both are caused by magnetic fields. The spots on these hot, extreme stars are brighter and hotter than the surrounding stellar surface, unlike on the Sun where we see spots as dark stains on the solar surface that are cooler than their surroundings. The spots on extreme horizontal branch stars are also significantly larger than sunspots, covering up to a quarter of the star’s surface. While sunspots vary in size, a typical size is around an Earth-size planet, 3000 smaller than a giant spot on an extreme horizontal branch star.

Video Credit: ESO

Go here for information about extreme horizontal branch stars.

The Medusa Nebula

ESO’s Very Large Telescope images the Medusa NebulaESO’s Very Large Telescope in Chile captured this image of the Medusa Nebula (also known Abell 21 and Sharpless 2-274). As the star at the heart of this nebula made its final transition into the final stage of its existence, it blew off its outer layers into space, forming this colorful cloud. The Sun will go through a similar process in a few billion years.

Image Credit: ESO

A Ring Galaxy

A Cosmic Hit and RunThe odd galaxy next to the bright foreground star in this picture is the Vela ring galaxy, visible as a bright core surrounded by a blue halo. As the name suggests, this ring galaxy is located in the southern constellation of Vela (The Sails). It is notable for its compact core and large circular belt of gas and stars.

It is thought that a ring galaxy like this is created when a small galaxy passes through the center of a larger one, triggering a shock wave that spreads outward. That forces gas to the galaxy’s periphery where it begins to collapse and form new stars. The Vela ring galaxy is unusual in that it actually exhibits at least two rings, suggesting that its collision was not a recent one.

Image Credit: ESO

NGC 3603

NGC 3603NGC 3603 is an open cluster of stars situated in the Carina spiral arm of the Milky Way around 20,000 light-years away from the Solar System. It’s the densest concentration of very massive stars known in the galaxy, and their strong ultraviolet radiation and stellar winds have cleared the gas and dust, giving an unobscured view of the cluster.

Image Credit: ESO