A Lonely Dwarf

The Local Void is a vast, empty region of space adjacent to the Local Group, the group of galaxies that included our Milky Way. It’s composed of three separate sectors which are separated by bridges of “wispy filaments” of gas and dust. The exact size of the Local Void is unknown, but it is at least 150 million light-years across—and possibly 3 to 6 times larger still. It’s called a void because it has significantly fewer galaxies than expected from standard cosmology.

The irregular dwarf galaxy in the foreground of the picture is cataloged as KK 246, and it’s one of the few galaxies in the Local Void.

Image Credit: NASA / ESA

A Stellar Nursery

This infrared view (click the image to embiggen it) made by the Herschel Space Observatory of Cygnus X spans some 6×2 degrees of one of the closest, massive star forming regions in the plane of our Milky Way galaxy. The rich stellar nursery already holds the massive star cluster known as the Cygnus OB2 association. Those stars are more evident by the region cleared by their energetic winds and radiation near the bottom center of the picture. They can’t be detected by Herschel instruments operating at long infrared wavelengths, but Herschel does reveal the region’s complex filaments of cool gas and dust around the locations where new massive stars are forming. Cygnus X lies some 4500 light-years away toward the heart of the northern constellation of the Swan. This picture covers a view about 500 light-years wide.

Image Credit: ESA

NGC 6814

A spiral snowflakeThis worth posting simply because it’s pretty.

NGC 6814 is an intermediate spiral galaxy in constellation Aquila located about 75 million light years from Earth. It’s a Seyfert galaxy with an extremely bright nucleus powered by a supermassive black hole with roughly 10 millions times the mass of the Sun. The galaxy is also a highly variable source of X-ray radiation. UV and optical emission also vary, although more smoothly, with time lag of two days behind the x-ray output.

Image Credit: ESA / NASA

Mergers and Acquisitions

Galaxy clusters are the largest objects in the universe held together by gravity. They can contain hundreds or thousands of galaxies held together in vast clouds of multi-million-degree gas glowing in X-rays.

The system known as Abell 2384 is the result of the collision of a pair galaxy cluster hundreds of millions of years ago. This composite image was put together using x-ray data from the Chandra X-ray Observatory and XMM-Newton (blue) and radio data from the Giant Metrewave Radio Telescope in India (red). It shows the superheated bridge of gas running through Abell 2384 and reveals the effects of a jet from a supermassive black hole in the center of a galaxy in one of the clusters. The jet is so powerful that it bends the shape of the 3 million light-year long gas bridge which has the mass of about 6 trillion Suns.

Image Credit: NASA

New Stars

NGC 346This image taken by the Hubble Space Telescope shows a population of infant stars in the Milky Way’s satellite galaxy, the Small Magellanic Cloud, located 210,000 light-years away. Some of the stars in the nebula NGC 346 are still forming from gravitationally collapsing gas clouds, and they have not yet ignited their hydrogen fuel to sustain nuclear fusion. The smallest of these infant stars is only half the mass of the Sun.

Image Credit: NASA / ESA