Ripped apart by a black hole

VLT watches in real time as gas cloud makes closest approach to the monster at the centre of the Milky Way

2013-07-17

(Press-News.org) In 2011 ESO's Very Large Telescope (VLT) discovered a gas cloud with several times the mass of the Earth accelerating towards the black hole at the centre of the Milky Way (eso1151 [1]. This cloud is now making its closest approach and new VLT observations show that it is being grossly stretched by the black hole's extreme gravitational field.

"The gas at the head of the cloud is now stretched over more than 160 billion kilometres around the closest point of the orbit to the black hole. And the closest approach is only a bit more than 25 billion kilometres from the black hole itself — barely escaping falling right in," explains Stefan Gillessen (Max Planck Institute for Extraterrestrial Physics, Garching, Germany) who led the observing team [2]. "The cloud is so stretched that the close approach is not a single event but rather a process that extends over a period of at least one year."

As the gas cloud is stretched its light gets harder to see. But by staring at the region close to the black hole for more than 20 hours of total exposure time with the SINFONI instrument on the VLT — the deepest exposure of this region ever with an integral field spectrometer [3] — the team was able to measure the velocities of different parts of the cloud as it streaks past the central black hole [4].

"The most exciting thing we now see in the new observations is the head of the cloud coming back towards us at more than 10 million km/h along the orbit — about 1% of the speed of light," adds Reinhard Genzel, leader of the research group that has been studied this region for nearly twenty years. "This means that the front end of the cloud has already made its closest approach to the black hole."

The origin of the gas cloud remains mysterious, although there is no shortage of ideas [5]. The new observations narrow down the possibilities.

"Like an unfortunate astronaut in a science fiction film, we see that the cloud is now being stretched so much that it resembles spaghetti. This means that it probably doesn't have a star in it," concludes Gillessen. "At the moment we think that the gas probably came from the stars we see orbiting the black hole."

The climax of this unique event at the centre of the galaxy is now unfolding and being closely watched by astronomers around the world. This intense observing campaign will provide a wealth of data, not only revealing more about the gas cloud [6], but also probing the regions close to the black hole that have not been previously studied and the effects of super-strong gravity.

INFORMATION:

Notes

[1] The black hole at the centre of the Milky Way is estimated to have a mass of about four million times that of the Sun and 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. The study of the supermassive black hole at the centre of the galaxy and its environment is rated number one in the list of ESO's top ten astronomical discoveries.

[2] The distance of closest approach is about five times the distance of the planet Neptune from the Sun. This is much too close for comfort to a black hole with a mass four million times that of the Sun!

[3] In an integral field spectrometer the light recorded in each pixel is separately spread out into its component colours and so spectra are recorded for each pixel. The spectra can then be analysed individually and used to create maps of the velocities and the chemical properties of each part of the object, for example.

[4] The team is also hoping to see evidence of how the rapidly moving cloud interacts with any ambient gas around the black hole. So far nothing has been found, but further observations are planned to look for such effects.

[5] Astronomers thought that the gas cloud might have been created by stellar winds from the stars orbiting the black hole. Or possibly even be the result of a jet from the galactic centre. Another option was that a star was at the centre of the cloud. In this case the gas would come either from a wind from the star, or from a planet-forming disc of gas and dust around the star.

[6] As this event at the centre of the galaxy unfolds, astronomers expect to see that the evolution of the cloud switches from purely gravitational and tidal to complex, turbulent hydrodynamics.

More information

This research was presented in a paper "Pericenter passage of the gas cloud G2 in the Galactic Center", by S. Gillessen et al, to appear in the Astrophysical Journal.

The team is composed of S. Gillessen (Max Planck Institute for Extraterrestrial Physics, Garching, Germany [MPE]), R. Genzel (MPE; Departments of Physics and Astronomy, University of California, Berkeley, USA), T. K. Fritz (MPE), F. Eisenhauer (MPE), O. Pfuhl (MPE), T. Ott (MPE), M. Schartmann (Universitätssternwarte der Ludwig-Maximilians-Universität, Munich, Germany [USM]; MPE), A. Ballone (USM; MPE) and A. Burkert (USM; MPE).

ESO is the foremost intergovernmental astronomy organisation in Europe and the world's most productive ground-based astronomical observatory by far. 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 the 39-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become "the world's biggest eye on the sky".

Links

Research paper - http://www.eso.org/public/archives/releases/sciencepapers/eso1332/eso1332a.pdf

Photos of the VLT - http://www.eso.org/public/images/archive/category/paranal/

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

Contacts

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

Reinhard Genzel
Max Planck Institute for Extraterrestrial Physics
Garching bei München, 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
Email: rhook@eso.org

ELSE PRESS RELEASES FROM THIS DATE:

New way to target an old foe: Malaria

2013-07-17

CAMBRIDGE, MA -- Although malaria has been eradicated in many countries, including the United States, it still infects more than 200 million people worldwide, killing nearly a million every year. In regions where malaria is endemic, people rely on preventive measures such as mosquito netting and insecticides. Existing drugs can help, but the malaria parasite is becoming resistant to many of them. Scientists working to develop new drugs and vaccines hope to target the parasite in the earliest stages of an infection, when it quietly reproduces itself in the human liver. In ...

Accurate prognosis for epilepsy patients

2013-07-17

Scientists at Bonn University Hospital and at the Max Planck Institute for neurological research in Cologne have developed a method with which the chances of success of a surgical procedure for temporal lobe epilepsy can be accurately predicted. The rate of accurate predictions is more than 90%. The results are now being presented in the scientific journal "NeuroImage:Clinical." When many nerve cells simultaneously fire in the brain, an epileptic seizure results. The most frequent form is temporal lobe epilepsy. It originates in one of the two temporal lobes which contain, ...

Injectable 'smart sponge' holds promise for controlled drug delivery

2013-07-17

Researchers have developed a drug delivery technique for diabetes treatment in which a sponge-like material surrounds an insulin core. The sponge expands and contracts in response to blood sugar levels to release insulin as needed. The technique could also be used for targeted drug delivery to cancer cells. "We wanted to mimic the function of health beta-cells, which produce insulin and control its release in a healthy body," says Dr. Zhen Gu, lead author of a paper describing the work and an assistant professor in the joint biomedical engineering program at North Carolina ...

Information in brain cells' electrical activity combines memory, environment, and state of mind

2013-07-17

The information carried by the electrical activity of neurons is a mixture of stored memories, environmental circumstances, and current state of mind, scientists have found in a study of laboratory rats. The findings, which appear in the journal PLoS Biology, offer new insights into the neurobiological processes that give rise to knowledge and memory recall. The study was conducted by Eduard Kelemen, a former graduate student and post-doctoral associate at the State University of New York (SUNY) Downstate Medical Center, and André Fenton, a professor at New York University's ...

Outgoing people lead happier lives

2013-07-17

Research from the University of Southampton has shown that young adults, who are more outgoing or more emotionally stable, are happier in later life than their more introverted or less emotionally stable peers. In the study, published in the Journal of Research in Personality, Dr Catharine Gale from the Medical Research Council's Lifecourse Epidemiology Unit, University of Southampton and a team from the University of Edinburgh and University College London, examined the effects of neuroticism and extraversion at ages 16 and 26 years on mental wellbeing and life satisfaction ...

Birds and humans have similar brain wiring

2013-07-17

A researcher from Imperial College London and his colleagues have developed for the first time a map of a typical bird brain, showing how different regions are connected together to process information. By comparing it to brain diagrams for different mammals such as humans, the team discovered that areas important for high-level cognition such as long-term memory and problem solving are wired up to other regions of the brain in a similar way. This is despite the fact that both mammal and bird brains have been evolving down separate paths over hundreds of millions of years. The ...

Danish survey evaluates the content of chemical contaminants in food

2013-07-17

The National Food Institute, Technical University of Denmark has evaluated the content of chemical contaminants in food in the period 2004-2011 at the request of the Danish Veterinary and Food Administration. The content of chemical contaminants is evaluated in relation to which specific foods Danes eat, and how much. The latest monitoring report includes even more compounds than the one from 2003. "Monitoring of unwanted compounds is performed to ensure that the food eaten by the Danish people does not contain too many harmful compounds. In general, Danes should not ...

Deciphering butterflies' designer colors: Findings could inspire new hue-changing materials

2013-07-17

WASHINGTON, July 17—Butterfly wings can do remarkable things with light, and humans are still trying to learn from them. Physicists have now uncovered how subtle differences in the tiny crystals of butterfly wings create stunningly varied patterns of color even among closely related species. The discovery, reported today in the Optical Society's (OSA) open-access journal Optical Materials Express, could lead to new coatings for manufactured materials that could change color by design, if researchers can figure out how to replicate the wings' light-manipulating properties. "It ...

The key to ion beams' polarizability

2013-07-17

Polarisability determines the force with which an inhomogeneous external electric field acts on the ions of an ion beam. However, it can be quite tricky to obtain accurate values for this force. Now, two German theoretical chemists, Volker Koch from Bielefeld University and Dirk Andrae from the Free University Berlin, have devised formulas providing the polarisability of atomic ions as a function of their total charge number. Their findings, about to be published in EPJ D, have implications for many applications, ranging from the use of ion beams for research purposes or ...

Monkey nation: Study confirms wealth of primates in Tanzania

2013-07-17

NEW YORK (July 17, 2013) — A five-year study by the Wildlife Conservation Society gives new hope to some of the world's most endangered primates by establishing a roadmap to protect all 27 species in Tanzania – the most primate-diverse country in mainland Africa. The study combines Tanzania's first-ever inventory of all primate species and their habitats with IUCN Red List criteria and other factors such as threats and rarity, ranking all 27 species from most vulnerable to least vulnerable. The authors then identify a network of "Priority Primate Areas" for conservation. ...

LAST 30 PRESS RELEASES:

People who are autistic and transgender/gender diverse have poorer health and health care

Gene classifier tests for prostate cancer may influence treatment decisions despite lack of evidence for long-term outcomes

Association of waist circumference with all-cause and cardiovascular mortalities in diabetes from the National Health and Nutrition Examination Survey 2003–2018