Best Ever Image Of A Star’s Surface, Atmosphere

To the unaided eye the famous, bright star Antares shines with a strong red tint in the heart of the constellation of Scorpius (The Scorpion). It is a huge and comparatively cool red supergiant star in the late stages of its life, on the way to becoming a supernova.

A team of astronomers, led by Keiichi Ohnaka, of the Universidad Católica del Norte in Chile, has now used ESO’s Very Large Telescope Interferometer (VLTI) at the Paranal Observatory in Chile to map Antares’s surface and to measure the motions of the surface material. This is the best image of the surface and atmosphere of any star other than the Sun.

The VLTI is a unique facility that can combine the light from up to four telescopes, either the 8.2-metre Unit Telescopes, or the smaller Auxiliary Telescopes, to create a virtual telescope equivalent to a single mirror up to 200 metres across. This allows it to resolve fine details far beyond what can be seen with a single telescope alone.

“How stars like Antares lose mass so quickly in the final phase of their evolution has been a problem for over half a century,” said Keiichi Ohnaka, who is also the lead author of the paper. “The VLTI is the only facility that can directly measure the gas motions in the extended atmosphere of Antares — a crucial step towards clarifying this problem.The next challenge is to identify what’s driving the turbulent motions.”

Using the new results the team has created the first two-dimensional velocity map of the atmosphere of a star other than the Sun. They did this using the VLTI with three of the Auxiliary Telescopes and an instrument called AMBER to make separate images of the surface of Antares over a small range of infrared wavelengths. The team then used these data to calculate the difference between the speed of the atmospheric gas at different positions on the star and the average speed over the entire star. This resulted in a map of the relative speed of the atmospheric gas across the entire disc of Antares — the first ever created for a star other than the Sun..

The astronomers found turbulent, low-density gas much further from the star than predicted, and concluded that the movement could not result from convection, that is, from large-scale movement of matter which transfers energy from the core to the outer atmosphere of many stars. They reason that a new, currently unknown, process may be needed to explain these movements in the extended atmospheres of red supergiants like Antares.

“In the future, this observing technique can be applied to different types of stars to study their surfaces and atmospheres in unprecedented detail. This has been limited to just the Sun up to now,” concludes Ohnaka. “Our work brings stellar astrophysics to a new dimension and opens an entirely new window to observe stars.”

Russian Scientists Use Cosmic Rays to Forecast Hurricanes

Scientists from the National Research Nuclear University MEPhI (Russia) appear to have found a way to better predict hurricanes by measuring changes in the atmosphere which precede giant atmospheric vortexes with air pressure subsiding to the center with very high speed of the airflow.


This can now be done with the use of a ‘muon hodoscope’. Muons are a byproduct of cosmic rays particles. A hodoscope is a type of detector commonly used in particle physics that make use of an array of detectors to determine the trajectory of an energetic particle – in this case cosmic rays.


Lead researcher Professor Igor Yashin of Moscow Engineering Physics Institute states: “The hurricane muon hodoscope is able to observe and analyze – on a real-time basis, modulations of the flow of secondary cosmic rays on the Earth’s surface provoked by processes in the heliosphere, magnetosphere and atmosphere of Earth. The uniqueness of our hodoscope is that in the real-time mode, it allows reconstruction of each muon’s track and obtaining muonographs.


It is hard to overstate the necessity of precise hurricane forecasting. Before artificial satellites, the only way to track hurricanes was via airplanes flying above the cyclones. But even today, satellites can’t provide comprehensive information. For example, they can’t detect the inner barometric pressure of the hurricane or the exact wind speed. Moreover, thick clouds obscure nascent cyclones from satellites. Despite the availability of satellite systems, sensors, and radars, aviation still plays an important role in forecasting.


According to scientists, the new hodoscope provides precise forecasts. To watch the atmosphere over Russia, which spans 10,625,447,387 miles (17.1 million km), the need for four hodoscopes are required. Considering that hurricanes are a fraction of that size, and the majority of tropical cyclones are formed between 10 and 30 degrees of latitude of both hemispheres, the number of hodoscope necessary to monitor this territory is low.

“Muon diagnostics developed at MEPhI offers the possibility to model the flow of cosmic rays in the atmosphere and magnetosphere. But to study such processes, it is necessary to create a network of similar, adjustable muon hodoscopes. Such hodoscopes were developed at MEPhI,” Yashin says.



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