Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Witnessing turbulent motion in the atmosphere of a distant star

23.08.2017

For the first time, astronomers have succeeded in obtaining a map of the turbulent motions in the atmosphere of a star other than the Sun, thanks to an innovative technique that combines three telescopes at the European Southern Observatory (ESO) on Cerro Paranal located in northern Chile. The astronomer Keiichi Ohnaka at the Universidad Católica del Norte in Antofagasta, Chile, led the research. He and his partners Gerd Weigelt and Karl-Heinz Hofmann from the Max Planck Institute for Radio Astronomy in Bonn, Germany obtained unprecedented velocity-resolved images of the surface and the atmosphere of a distant star.

The team was able to measure the intensity (Figure 1) and velocity of the gas at each position over the surface and atmosphere of the red supergiant star Antares (Alpha Scorpii) at a distance of about 600 light years.


First image of Antares: stellar disk (yellow) with two brighter regions (white) and the extended atmosphere (blue). The red supergiant has a diameter 700 times larger than the diameter of our Sun.

K. Ohnaka et al. 2017, Nature 548, 310

“For the first time, we have succeeded in obtaining a two-dimensional map of the dynamics, that is, the motions in the atmosphere of a star other than the Sun. The observations were performed with ESO’s Very Large Telescope Interferometer (VLTI) and the AMBER beam combiner instrument. The gas velocity can be derived from shifts of spectral lines because of the Doppler effect“, explains Keiichi Ohnaka.

When stars approach the end of their life, they start to lose material from the surface and atmosphere— a process called mass loss. While red supergiant stars like Antares are known to be experiencing intense mass loss, it is still unknown how it occurs—actually a long-standing problem over half a century.

One of the best ways to investigate this process is to observe the dynamics of the gas—the motions and the velocity—close to the star. Some images of the surface of stars had been taken before, but only for a very limited number of cases and without information about the gas motions in the atmosphere.

Single telescopes are not able to resolve surface structures on stars other than our Sun. However, if one combines („interferes“) the light from several telescopes, the required high angular resolution can be obtained. This method is called interferometry.

“The achievable resolution is proportional to the distance between the individual telescopes”, explains Karl-Heinz Hofmann. “We used the AMBER beam combiner instrument of ESO’s Very Large Telescope Interferometer for our observations because it allows us to perform measurements with high spectral resolution and to measure velocities“.

“If we obtain maps of the gas motions at different heights throughout the atmosphere, we can obtain a three-dimensional picture of how the gas is moving in the atmosphere of stars,” emphasizes Keiichi Ohnaka. The team is already working on such a project, going from 2D to 3D, aiming at finally solving the mystery behind the mass-loss process.

The images of Antares provide new clues for understanding how this star loses mass. The team found out that the material is not spilling out in an ordered manner in Antares but the material is expelled in a random and turbulent manner.

“This interferometric imaging method allows us to study not only stars in late evolutionary stages, but also, for example, very young stars surrounded by circumstellar disks, in which planets can form, and even extragalactic objects”, concludes Gerd Weigelt. “In all these projects, it is of greatest importance to obtain both high angular resolution and high spectral resolution to study the velocity distribution in the gas.” In the future, the new VLTI instrument MATISSE will provide a unique opportunity to perform such observations in a wide wavelength range for the first time.

Original Paper:

Vigorous atmospheric motion in the red supergiant star Antares, K. Ohnaka, G. Weigelt & K.-H. Hofmann, 2017, Nature (August 17, 2017).

Contact:

Prof. Dr. Gerd Weigelt,
Head of Research Group Infrared Astronomy
Max-Planck-Institut für Radioastronomie, Bonn.
Fon: +49 228 525-243
E-mail: gweigelt@mpifr-bonn.mpg.de

Prof. Dr. Keiichi Ohnaka,
Instituto de Astronomía, Universidad Católica del Norte
Fon: +56 55 2355493
E-mail: k1.ohnaka@gmail.com

Dr. Karl-Heinz Hofmann,
Max-Planck-Institut für Radioastronomie, Bonn.
Fon: +49 228 525-290
E-mail: khh@mpifr-bonn.mpg.de

Dr. Norbert Junkes,
Press and Public Outreach
Max-Planck-Institut für Radioastronomie, Bonn.
Fon: +49 228 525-399
E-mail: njunkes@mpifr-bonn.mpg.de

Weitere Informationen:

http://www.mpifr-bonn.mpg.de/pressreleases/2017/6

Norbert Junkes | Max-Planck-Institut für Radioastronomie

More articles from Physics and Astronomy:

nachricht Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics

nachricht What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>