Close-up view of the two bright galactic nuclei.Īccording to Voggel, this is the first time that stellar velocity measurements are used to reveal the existence of a dual supermassive black hole. This allows velocity measurements very close to the black hole, from which the black hole’s mass can be calculated. MUSE provides extremely high spatial resolution (enabled by adaptive optics to account for turbulent air), giving a spectrum for each and every 0.025-arcsecond pixel in its field of view. The spread of velocities indicates black hole masses of 154 million and 6.3 million solar masses for the first and second nucleus, respectively. Using the Multi Unit Spectroscopic Explorer (MUSE) on the European Southern Observatory’s Very Large Telescope in Chile, the team measured the bulk motions of stars in and around the two nuclei. “We’re really lucky that they are close together but have not yet merged,” says Voggel. That’s close enough for them to spiral in and collide within just 250 million years or so. Now, in Astronomy & Astrophysics, a largely European team of astronomers led by Karina Voggel (Strasbourg Observatory, France) presents evidence that both of the galaxy’s two nuclei harbor a supermassive black hole, separated by some 1,600 light-years. This “second nucleus” turned out to produce faint X-rays, leading Schweizer and his colleagues to suggest that it might be the stripped core of a smaller galaxy with a mildly active central black hole that merged with NGC 7727 some 2 billion years ago. Three years ago, a team led by François Schweizer (Carnegie Observatories) reported a compact, bluish concentration of stars just off of the bright center of NGC 7727, a somewhat distorted galaxy in the constellation Aquarius. Each nucleus consists of a dense group of stars with a supermassive black hole at the center. This image shows close-up (left) and wide (right) views of the two bright nuclei of NGC 7727, each hosting a supermassive black hole. In the future, the pair will collide, releasing powerful gravitational waves.
![super masive blackhole super masive blackhole](http://4.bp.blogspot.com/-ymp5TdZPfo8/U5hO0VDZYuI/AAAAAAAAJRg/tMiG1XAM3tc/s1600/black-hole-star-accretion..jpg)
Astronomers have identified and weighed the nearest dual supermassive black hole, in a galaxy just 89 million light-years away.