Best Ever Image of a Star’s Surface and Atmosphere

Saturday, August 26, 2017

Best Ever Image of a Star’s Surface and Atmosphere

Best Ever Image of a Star’s Surface and Atmosphere:

Using ESO’s Very Large Telescope Interferometer astronomers have constructed this remarkable image of the red supergiant star Antares. This is the most detailed image ever of this object, or any other star apart from the Sun. Credit: ESO/K. Ohnaka

Using ESO’s Very Large Telescope Interferometer astronomers have constructed the most detailed image ever of a star — the red supergiant star Antares. They have also made the first map of the velocities of material in the atmosphere of a star other than the Sun, revealing unexpected turbulence in Antares’s huge extended atmosphere. The results were published in the journal Nature.

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-meter Unit Telescopes, or the smaller Auxiliary Telescopes, to create a virtual telescope equivalent to a single mirror up to 200 metes 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.”

Credit: ESO

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The National Aeronautics and Space Administration (NASA) is the United States government agency responsible for the civilian space program as well as aeronautics and aerospace research. President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA's predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

UFO SIGHTINGS PHOTO PHOTOGRAPHY

The Oxford English Dictionary defines a UFO as "An unidentified flying object; a 'flying saucer'." The first published book to use the word was authored by Donald E. Keyhoe. The acronym "UFO" was coined by Captain Edward J. Ruppelt, who headed Project Blue Book, then the USAF's official investigation of UFOs. He wrote, "Obviously the term 'flying saucer' is misleading when applied to objects of every conceivable shape and performance. For this reason the military prefers the more general, if less colorful, name: unidentified flying objects. UFO (pronounced Yoo-foe) for short." Other phrases that were used officially and that predate the UFO acronym include "flying flapjack", "flying disc", "unexplained flying discs", "unidentifiable object", and "flying saucer". The phrase "flying saucer" had gained widespread attention after the summer of 1947. On June 24, a civilian pilot named Kenneth Arnold reported seeing nine objects flying in formation near Mount Rainier. Arnold timed the sighting and estimated the speed of discs to be over 1,200 mph (1,931 km/h). At the time, he described the objects' shape as being somewhat disc-like or saucer-like, leading to newspaper accounts of "flying saucers" and "flying discs". In popular usage the term UFO came to be used to refer to claims of alien spacecraft. and because of the public and media ridicule associated with the topic, some investigators prefer to use such terms as unidentified aerial phenomenon (or UAP) or anomalous phenomena, as in the title of the National Aviation Reporting Center on Anomalous Phenomena (NARCAP).

UFO PHOTO PHOTOGRAPHY

UFO - Unidentified Flying Object An unidentified flying object, or UFO, in its most general definition, is any apparent anomaly in the sky that is not identifiable as a known object or phenomenon. Culturally, UFOs are associated with claims of visitation by extraterrestrial life or government-related conspiracy theories, and have become popular subjects in fiction. While UFOs are often later identified, sometimes identification may not be possible owing to the usually low quality of evidence related to UFO sightings (generally anecdotal evidence and eyewitness accounts). Stories of fantastical celestial apparitions have been told since antiquity, but the term "UFO" (or "UFOB") was officially created in 1953 by the United States Air Force (USAF) to serve as a catch-all for all such reports. In its initial definition, the USAF stated that a "UFOB" was "any airborne object which by performance, aerodynamic characteristics, or unusual features, does not conform to any presently known aircraft or missile type, or which cannot be positively identified as a familiar object." Accordingly, the term was initially restricted to that fraction of cases which remained unidentified after investigation, as the USAF was interested in potential national security reasons and/or "technical aspects" (see Air Force Regulation 200-2). During the late 1940s and through the 1950s, UFOs were often referred to popularly as "flying saucers" or "flying discs". The term UFO became more widespread during the 1950s, at first in technical literature, but later in popular use. UFOs garnered considerable interest during the Cold War, an era associated with a heightened concern for national security. Various studies have concluded that the phenomenon does not represent a threat to national security nor does it contain anything worthy of scientific pursuit (e.g., 1951 Flying Saucer Working Party, 1953 CIA Robertson Panel, USAF Project Blue Book, Condon Committee).

Photos of Nature | Nature Photography What is The Universe

Photos of Nature | Nature Photography What is The Universe

Saturday, August 26, 2017