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When Betelgeuse mysteriously dimmed in late 2019 by over a magnitude, astronomers all over the world rushed to show their telescopes to the pink big star on Orion’s shoulder.
Little did they know that they had been being joined by a Japanese climate satellite tv for pc named Himawari-8.
From its geostationary orbit, Himawari-8 takes high-resolution photographs of Earth, capturing clouds, adjustments in vegetation — and sometimes, photobombing astronomical objects, showing simply off Earth’s limb. Impressed by a tweet of a Himawari-8 image that had serendipitously captured the Moon, two graduate college students on the College of Tokyo, Daisuke Taniguchi and Shinsuke Uno, puzzled if they may harness the climate satellite tv for pc’s archives for astronomical analysis.
They discovered that Betelgeuse appeared in Himawari-8’s photographs roughly as soon as each 1.72 days — together with earlier than, throughout, and after its enigmatic interval of dimming from 2019 to 2020. What’s extra, Himawari-8’s digital camera operates at mid-infrared wavelengths, the place it could see temperature variations between clouds and the bottom. That wavelength vary can also be good for observing astronomical mud, just like the mud that shrouds younger stars — or the mud that some astronomers suppose briefly blocked Betelgeuse’s gentle and triggered it to dim.
To assist analyze Himawari-8’s knowledge, Taniguchi and Uno recruited Kazuya Yamazaki, a graduate scholar in meteorology, and the trio revealed their outcomes Could 30 in Nature Astronomy. From the satellite tv for pc’s knowledge, they had been in a position to estimate the quantity of mud round Betelgeuse. They discovered that the dimming is almost certainly because of a mix of mud and in addition a cooling of the star’s temperature by about 250 levels Fahrenheit (140 levels Celsius). That is per one of the common theories — that Betelgeuse expelled a scorching clump of fuel that condensed into mud when uncovered to a cool area on the star’s floor.
The workforce suppose climate satellites have a number of unrealized potential as astronomical telescopes. Mid-infrared radiation is blocked by Earth’s environment, rendering it invisible to ground-based telescopes. There’s additionally a dearth of space-based observatories at present working within the mid-IR. The Spitzer Area Telescope has been decommissioned since January 2020, and the SOFIA airborne observatory will even be shut down later this 12 months. Whereas the upcoming James Webb Area Telescope will be capable of observe within the mid-IR, its time is so valuable it received’t be capable of have a look at one object repeatedly for years on finish as climate satellites can.
Taniguchi says he and his colleagues have already begun different tasks with Himawari-8 knowledge, together with making a catalog of tens of different big stars and looking for transient infrared objects. “I hope another astronomers on the planet will begin their very own tasks utilizing Himawari-8 or different meteorological satellites,” he instructed Astronomy.
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