Astronomers have found a pair of extraordinary cosmic objects that dramatically burst in X-rays, flaring up to become about a hundred times brighter in less than a minute, before returning to original X-ray levels after about an hour. This discovery may represent a new class of explosive events found in space.
Using data from NASA’s Fermi Gamma-ray Space Telescope and other facilities, an international team has found the first gamma-ray binary in another galaxy and the most luminous one ever seen. The dual-star system, dubbed LMC P3, contains a massive star and a crushed stellar core that interact to produce a cyclic flood of gamma rays.
Gamma-ray bursts, or GRBs, are some of the most violent and energetic events in the universe. Although these events are the most luminous explosions astronomers can observe, a new study using NASA’s Chandra X-ray Observatory, NASA’s Swift satellite and other Earth-based telescopes suggests that scientists may be missing a majority of these powerful cosmic detonations.
The European Space Agency’s orbiting XMM-Newton X-ray observatory has proved the existence of a ‘gravitational vortex’ around a black hole. The discovery, aided by NASA’s NuSTAR mission, solves a mystery that has eluded astronomers for more than 30 years and will allow them to map the behaviour of matter very close to black holes.
Some 3.9 billion years ago in the heart of a distant galaxy, the intense tidal pull of a monster black hole shredded a star that passed too close. After X-rays produced in this event first reached Earth on 28 March 2011, scientists concluded that the outburst, now known as Swift J1644+57, also represented the sudden flare-up of a previously inactive black hole.
Researchers from MIT and Harvard University have developed a new algorithm that could help astronomers produce the first image of a black hole. The algorithm would stitch together data collected from radio telescopes scattered around the globe in an international collaboration called the Event Horizon Telescope. The project seeks, essentially, to turn the entire planet into a large radio telescope dish.
Discovered in 1784 by William Herschel, NGC 4394 is the archetypal barred spiral galaxy, with bright spiral arms emerging from the ends of a bar that cuts through the galaxy’s central bulge. Some 55 million light-years from Earth, the galaxy lies in the constellation of Coma Berenices. NGC 4394 is considered to be a member of the Virgo Cluster.
In June 2015, V404 Cygni underwent dramatic brightening for about two weeks, as it devoured material that it had stripped off an orbiting companion star. Violent red flashes, lasting just fractions of a second, were observed during the flare-up — one of the brightest black hole outbursts in recent years.
Astronomers for the first time have detected repeating short bursts of radio waves from an enigmatic source that is likely located well beyond the edge of our Milky Way galaxy. The findings indicate that these “fast radio bursts” come from an extremely powerful object which occasionally produces multiple bursts in under a minute.
Surrounding the black hole at the centre of our Milky Way galaxy and stretching out to about 700 light-years, is a dense zone of activity called the Central Molecular Zone (CMZ). It contains many dense molecular clouds that would normally be expected to produce new stars, but which are instead eerily desolate. Where did the CMZ come from? No place else in the Milky Way is remotely like it.
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