A black hole's dinner is fast approaching

December 14, 2011

During a 20-year programme using ESO telescopes to monitor the movement of stars around the supermassive black hole at the centre of our galaxy (eso0846 - http://www.eso.org/public/news/eso0846/) [1], a team of astronomers led by Reinhard Genzel at the Max-Planck Institute for Extraterrestrial Physics (MPE) in Garching, Germany, has discovered a unique new object fast approaching the black hole.

Over the last seven years, the speed of this object has nearly doubled, reaching more than 8 million km/h. It is on a very elongated orbit [2] and in mid-2013 it will pass at a distance of only about 40 billion kilometres from the event horizon of the black hole, a distance of about 36 light-hours [3]. This is an extremely close encounter with a supermassive black hole in astronomical terms.

This object is much cooler than the surrounding stars (only about 280 degrees Celsius), and is composed mostly of hydrogen and helium. It is a dusty, ionised gas cloud with a mass roughly three times that of the Earth. The cloud is glowing under the strong ultraviolet radiation from the hot stars around it in the crowded heart of the Milky Way.

The current density of the cloud is much higher than the hot gas surrounding the black hole. But as the cloud gets ever closer to the hungry beast, increasing external pressure will compress the cloud. At the same time the huge gravitational pull from the black hole, which has a mass four million times that of the Sun, will continue to accelerate the inward motion and stretch the cloud out along its orbit.

"The idea of an astronaut close to a black hole being stretched out to resemble spaghetti is familiar from science fiction. But we can now see this happening for real to the newly discovered cloud. It is not going to survive the experience," explains Stefan Gillessen (MPE) the lead author of the paper.

The cloud's edges are already starting to shred and disrupt and it is expected to break up completely over the next few years [4]. The astronomers can already see clear signs of increasing disruption of the cloud over the period between 2008 and 2011.

The material is also expected to get much hotter as it nears the black hole in 2013 and it will probably start to give off X-rays. There is currently little material close to the black hole so the newly-arrived meal will be the dominant fuel for the black hole over the next few years.

One explanation for the formation of the cloud is that its material may have come from nearby young massive stars that are rapidly losing mass due to strong stellar winds. Such stars literally blow their gas away. Colliding stellar winds from a known double star in orbit around the central black hole may have led to the formation of the cloud.

"The next two years will be very interesting and should provide us with extremely valuable information on the behaviour of matter around such remarkable massive objects," concludes Reinhard Genzel.

[1] The black hole at the centre of the Milky Way is formally known as Sgr A* (pronounced Sagittarius A star). It is the closest supermassive black hole known by far and hence is the best place to study black holes in detail.

[2] The observations were made using the NACO infrared adaptive optics camera and the SINFONI infrared spectrograph, both attached to the ESO Very Large Telescope in Chile. The centre of the Milky Way lies behind thick dust clouds that scatter and absorb visible light and must be observed at infrared wavelengths where the clouds are more transparent.

[3] A light-hour is the distance that light travels in one hour. It is a little more than the distance from the Sun to the planet Jupiter in the Solar System. For comparison the distance between the Sun and the nearest star is more than four light-years. The cloud will pass at less than ten times the distance from the Sun to Neptune from the black hole

[4] This effect well known from the physics of fluids and can be seen when for example pouring syrup in a glass of water. The flow of syrup downwards through the water will be disrupted and the droplet will break apart -- effectively diluting the syrup in the water.

More information

This research was presented in a paper "A gas cloud on its way towards the super-massive black hole in the Galactic Centre", by S. Gillessen et al., to appear in the 5 January 2012 issue of the journal Nature.

The team is composed of S. Gillessen (Max-Planck-Institut für extraterrestrische Physik [MPE], Germany), R. Genzel (MPE; Department of Physics, University of California [UC], USA), T. Fritz (MPE, Germany), E. Quataert (Department of Astronomy, UC, USA), C. Alig (Universitätssternwarte der Ludwig-Maximilians-Universität [LMU], Germany), A. Burkert (MPE; LMU), J. Cuadra (Departamento de Astronomía y Astrofísica, Pontificia Universidad Católica de Chile, Chile), F. Eisenhauer (MPE), O. Pfuhl (MPE), K. Dodds-Eden (MPE), C. Gammie (Center for Theoretical Astrophysics, University of Illinois, USA), T. Ott (MPE).

ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world's most productive astronomical observatory. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world's most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world's largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 40-metre-class European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become "the world's biggest eye on the sky".


- Research paper in Nature: http://www.eso.org/public/archives/releases/sciencepapers/eso1151/eso1151.pdf

- MPE web page on the Galactic Centre: http://www.mpe.mpg.de/ir/GC/index.php

- Images of Paranal: http://www.eso.org/public/images/archive/category/paranal/


Stefan Gillessen
Max-Planck Institute for Extraterrestrial Physics
Garching, Germany
Tel: +49 89 30000 3839
Email: ste@mpe.mpg.de

Reinhard Genzel
Max-Planck Institute for Extraterrestrial Physics
Garching, Germany
Tel: +49 89 30000 3281
Email: genzel@mpe.mpg.de

Richard Hook
ESO, La Silla, Paranal, E-ELT & Survey Telescopes Press Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org


Related Black Hole Articles from Brightsurf:

Black hole or no black hole: On the outcome of neutron star collisions
A new study lead by GSI scientists and international colleagues investigates black-hole formation in neutron star mergers.

The black hole always chirps twice: New clues deciphering the shape of black holes
A team of gravitational-wave scientists led by the ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav) reveal that when two black holes collide and merge, the remnant black hole 'chirps' not once, but multiple times, emitting gravitational waves--intense ripples in the fabric space and time--that inform us about its shape.

Wobbling shadow of the M87 black hole
New analysis from the Event Horizon Telescope (EHT) Collaboration reveals the behavior of the supermassive black hole in the center of the M87 galaxy across multiple years, indicating the crescent-like shadow feature appears to be wobbling.

How to have a blast like a black hole
Scientists at Osaka University have created magnetized-plasma conditions similar to those near a black hole using very intense laser pulses.

Black hole collision may have exploded with light
Astronomers have seen what appears to the first light ever detected from a black hole merger.

Black hole's heart still beating
The first confirmed heartbeat of a supermassive black hole is still going strong more than ten years after first being observed.

Black hole team discovers path to razor-sharp black hole images
A team of researchers have published new calculations that predict a striking and intricate substructure within black hole images from extreme gravitational light bending.

Planets around a black hole?
Theoreticians in two different fields defied the common knowledge that planets orbit stars like the Sun.

Black hole mergers: Cooking with gas
Gravitational wave detectors are finding black hole mergers in the universe at the rate of one per week.

Going against the flow around a supermassive black hole
At the center of a galaxy called NGC 1068, a supermassive black hole hides within a thick doughnut-shaped cloud of dust and gas.

Read More: Black Hole News and Black Hole Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.