A Galactic Merger

One from manyThis is an odd galaxy known as NGC 1487. It’s not a single galaxy but two or more galaxies in the act of merging. Each of the old galaxies has lost almost all traces of its original appearance as the stars and gas have been thrown about by gravitational interactions. Unless one of the merging galaxies is very much bigger than the other(s), galaxies are always disrupted by the violence of the merging process, so it’s essentially impossible to determine exactly what the original galaxies looked like or how many of them there were. In this case, it may be that this NGC 1487 is the merger of several dwarf galaxies that were previously part of a small group.

Although older yellow and red stars can be seen in the outer regions of the new galaxy, its general appearance is dominated by bright blue stars that probably formed in a burst of star formation triggered by the merger.

Image Credit: ESA / NASA

Trumpler 14

Trompler 14This glittering star cluster that contains some of the brightest stars our galaxy. Trumpler 14 is located 8,000 light-years away in a large star-formation region called the Carina Nebula. Because the cluster is relatively young, only 500,000 years old, it has one of the highest concentrations of massive, luminous stars in the entire Milky Way.

The dark spot left of center is a blob of gas and dust seen in silhouette.

Image Credit: NASA / ESA

A Blue Compact Dwarf

True blueThis about a kind of galaxy, not a smurf. The blue cluster of stars in this Hubble Space Telescope picture is a galaxy known as UGC 11411. It’s a kind of galaxy known as an irregular blue compact dwarf (BCD) galaxy. BCD galaxies are about a tenth of the size of a typical spiral galaxy such as the Milky Way. They’re made up of large clusters of hot, massive stars that ionize the surrounding gas with their intense radiation. Because these stars are so hot they glow brightly blue hue. The stars in UGC 11411 are very young by stellar standards, only around 10 million years or so. They were created during a starburst, a galaxy-wide episode of furious star formation. UGC 11411 has an extremely high star formation rate, even for a BCD galaxy.

Because BCDs don’t contain either a lot of dust or the heavy elements that are typically found as trace elements in recently formed stars, their composition is very similar to that of the material from which the first stars formed in the early universe. This makes BCD galaxies to be good objects to study to improve our understanding of the primordial star-forming processes in the early history of the Universe.

The bright stars in the image are in our own Milky Way galaxy.

Image Credit: ESA / NASA

Hercules A

Hercules AHercules A, also known as 3C 348, lies around two billion light-years away. It is one of the brightest sources of radio emission outside our Galaxy. It’s the bright object at the middle of the frame, an elliptical galaxy. As seen in visible light by the Hubble Space Telescope it appears floating serenely in the inky blackness of space, but adding data from a radio telescope radically transforms the image. Jets of material can be seen billowing outwards from the galaxy when viewed at radio frequencies—jets that are completely undetectable in visible light. The image above combines data from the Very Large Array radio observatory in New Mexico with data from Hubble‘s Wide Field Camera 3.

The two jets are composed of hot, high-energy plasma that has been flung from Hercules A by a supermassive black hole lurking at the galaxy’s core. This black hole is roughly 2.5 billion times the mass of the Sun. That’s about a thousand times more massive than the black hole at the centre of the Milky Way.

Hercules A’s black hole accelerates the ejected material to nearly the speed of light, sending it flying out into intergalactic space. Eventually, the highly focused jets lose energy, slowing down and spreading out to form cloud-like blobs The multiple bright rings and knots seen within these blobs suggest that the black hole has sent out successive bursts of material. The jets stretch for around 1.5 million light-years, around 15 times the size of the Milky Way.

Image Credit: NASA / ESA / VLA


Philae’s Multiple Landings

Data from both the Philae lander and Rosetta orbiter experiments have been used along with simulations based on Philae’s mechanical design to reconstruct the lander’s attitude and motion during its descent and multiple touchdowns on Comet 67P/Churyumov-Gerasimenko on 12 November, 2014.

[youtube https://www.youtube.com/watch?v=rJ2eqH3Bz4c]

Video Credit: ESA