Burts of Gamma Rays from Blackhole...

A black hole has been spotted belching out a burst of gamma rays after gulping down part of a nearby star, something never seen before. Such violent burps may actually be the most common type of explosive "gamma-ray burst" in the universe.
The event was named GRB 070610 after the date of its discovery by NASA's Swift satellite on 10 June 2007.

At first it looked like another ordinary long gamma-ray burst (GRB) in a distant galaxy. These outbursts are thought to be the death cries of massive stars collapsing to form black holes.

But this GRB seems to have a different provenance altogether. They suspect that the black hole in the system had some kind of a giant hiccup while chowing down on matter stolen from its companion star. This gamma-ray hiccup behaviour has never been seen before and scientists are not sure how to explain it. But though the burst was much less powerful than typical long GRBs, such events are still quite violent. A similar system called V4641 Sgr set the record for spewing matter out at the highest speed ever observed in our galaxy during a similar outburst, observed in X-rays, in 1999.

It's clearly an unusual event. There's yet another way that nature found to make GRBs, which is very interesting. Low energy
"The reason we haven't seen something like this before is not because it's rare but because it's a low-energy event," Kasliwal says, explaining that this burst is intrinsically about 100 trillion times less powerful than previously observed long GRBs. Those more powerful long GRBs have only been observed in other galaxies and are thought to occur in our own galaxy less than once every 100,000 years

Four Massive Galaxies Colliding...

Four massive galaxies are colliding in the largest galactic merger ever seen, new observations reveal. The smash-up is shedding light on how the biggest galaxies in the universe form – and why many of them stopped giving birth to stars billions of years ago.

Astronomers classify mergers according to the relative sizes of the galaxies involved. Now, researchers led by Kenneth Rines of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, US, have found the largest major merger ever seen. It involves a quartet of galaxies at the centre of a galactic cluster known as CL0958+4702, which lies about 5 billion light years from Earth.Three of the merging galaxies are the size of the Milky Way, while the other is about three times as massive
Star plume
Using infrared observations by the Spitzer Space Telescope and optical images from the WIYN Observatory in Arizona, US, the team also discovered a colossal, fan-shaped 'plume' of old, red stars trailing about 360,000 light years from the merger, apparently tossed out of the galaxies as they spiralled towards each other. "That's the other fairly amazing thing – the number of stars in the plume is about three Milky Ways' worth. Eventually, about half of those stars will likely fall into the merged galaxies – which are expected to coalesce into a single mammoth galaxy in about 100 million years – while the other half will float freely outside it, he says. That suggests other free-floating stars previously found within galaxy clusters were also ejected from their birth galaxies during major mergers. This answers the question of how you form the most massive galaxies in the universe." That is because the most massive galaxies yet observed – weighing about 10 times the Milky Way – are found at the centres of nearby galaxy clusters, which are seen as they are now, 13.7 billion years after the big bang. Interestingly, the four merging galaxies are made of old, red stars, suggesting each had lost the gas necessary to form new stars long beforehand, within 5 billion years of the big bang. That agrees with other recent observations showing that galaxies within clusters – which typically contain hundreds of galaxies – contain fewer young stars than those lying outside clusters. The four newly discovered merging galaxies lie 5 billion light years away, meaning astronomers see them as they were 5 billion years ago!!!

Comet-like Tail of Star Mira!!

A glowing, comet-like tail has been discovered trailing behind a double star called Mira, a phenomenon never seen before. It may contain clues about the star's activity over the past 30,000 years.Mira, which means "wonderful" in Latin, is one of the best-studied star systems in the sky and lies 350 light years from Earth. One star in the pair, called Mira A, is a bloated, ageing red giant that sheds large amounts of gas and dust into space, while the other, Mira B, is a dense stellar corpse called a white dwarf.
Previous studies had shown that some of the material from Mira A's wind has collected into a disc – which could potentially form planets – around Mira B (see Dying star's wind creates planetary nursery).
Now astronomers led by Christopher Martin of Caltech in Pasadena, US, have discovered the long tail, which is visible only in far ultraviolet light. They happened upon it using NASA's Galaxy Evolution Explorer (GALEX) satellite, which was surveying the sky at ultraviolet wavelengths.The tail extends 13 light years from Mira – if it were visible in the sky, it would span the width of four full Moons. It appears to trace the path of Mira's motion across the sky over the past 30,000 years, based on its size and Mira's speed, which has been previously measured.
Martin's team believes the tail is created as a result of Mira A's stellar wind – an outflow of gas and dust from the star – hitting ambient gas as it moves through space. Fast-moving electrons generated by the collision then strike hydrogen molecules in surrounding gas, producing ultraviolet light. This creates a glowing trail behind Mira as it travels through the galaxy at 130 kilometres per second. the tail could shed light on why some stars turn into white dwarfs and others explode as supernovae.stars such as Mira A, which start out with a few times the mass of the Sun, avoid this fate by shedding most of their mass in stellar winds to become placid white dwarfs