Astronomers have a new way to study the stars: take advantage of meteorological satellites orbiting the Earth.
This is the conclusion of a new document that presents new data from a Japanese meteorological satellite that accidentally observed the red supergiant. Betelgeuse during a period of unexplained eclipse. Random observations could mean a new tool for astronomers trying to figure out how a red supergiant loses mass and eventually explodes as supernova.
The second brightest star in constellation Orion, Bethelgeise (pronounced “bet-orl-gerz” or “beetlejuice”) is the 10th brightest star in the night sky. But from October 2019 to February 2020, it drastically reduced to about two-thirds of its normal brightness. This so-called “great eclipse” event has led to speculation that it is about to explode like what scientists call an IIP supernova, which it will certainly do in the next 100,000 years.
Connected: Orion and his eclipse star Betelgeuse shine above the star gauge in this sentimental picture of the night sky
Scientists analyzing the event used mostly data from ground-based optical telescopes. Astronomers have often come to the conclusion that the eclipse of Betelgeuse is the result of either the cooling of its surface, the formation of a new strip of dust around it, or both.
Ground-based telescopes cannot see through dust and gas into space, which requires infrared vision. This is because Earth’s atmosphere blocks infrared radiation, as well as X-rays, gamma rays and most ultraviolet rays. So only space observatories can see infrared light – and that includes meteorological satellites such as Himavari-8 (opens in a new section), one of the geostationary meteorological satellites of the Japan Meteorological Agency.
And Himawari-8’s astrophysical debut began in an unlikely place: Twitter.
“We saw a tweet saying that the moon is in her images,” said Daisuke Taniguchi, Ph.D. a student of astronomy at the University of Tokyo and the first author of the article, told Space.com. “I spoke with [third author] Shinsuke Uno, on the use of meteorological satellites for astronomy, found that Betelgeuse was in the field of view of Himavari-8 and realized that perhaps the Great Eclipse of Betelgeuse could be studied. “
Himawari-8 has been positioned 22,236 miles (35,786 kilometers) above the Earth’s equator since 2015 to study weather and natural disasters (including the eruption of the Hongga volcano Tonga-Hunga Haapai on January 15). Although the satellite is there to depict the Earth every 10 minutes, the edges of its images include stars.
Taniguchi and his colleagues were able to see Betelgeuse in images taken throughout the life of the Himawari-8, and measured its brightness approximately every 1.7 days between January 2017 and June 2021. A Advanced Himawari Imager (AHI) of the satellite he studied Betelgeuse in two ways.
“At optical and near-infrared wavelengths, stardust obscures light from the star’s surface,” Taniguchi said, explaining that researchers – like astronomers limited to using ground-based telescopes – have been able to estimate the amount of stardust around Betelgeuse.
However, near-star dust emits only medium infrared light. “By observing such average infrared light, we can see the dust itself and we can directly measure the time series of the amount of dust around Betelgeuse,” Taniguchi said. The team concluded that the “big eclipse” in 2019 and 2020 was caused by two factors in almost equal proportions: the star’s temperature dropped by approximately 250 degrees Fahrenheit (140 degrees Celsius) and dust condensed from hot gas around the star.
Most importantly, this theory is in broad agreement with the conclusion of astronomers using ground-based telescopes. For example, a study led by the Chinese Academy of Sciences cites a giant sunspots and temperature fluctuations while results from the Very Large Telescope of the European Southern Observatory in Chile and from the Hubble Space Telescope offer Betelgeuse ejected a huge cloud of gas, which cooled and condensed into dust.
New discoveries by scientists suggest that meteorological satellites could be used as space telescopes for astronomy. “This allows us to obtain high-cadence time series from medium-infrared images that are difficult to obtain with conventional astronomical instruments,” the article said. In addition to not being able to record near-infrared data, terrestrial telescopes lose sight of some stars for several months while the sun floats in front of them.
“This is an opportunity I haven’t seen explored much before,” Emily Levescu, author of The Last Starship and an astronomer focused on red supergiants at the University of Washington who did not participate in the new research, told Space. com.
“It certainly depends in part on chance, but observations like these can be a great resource for bright, close red supergiants,” she said. “Especially since they could complement the upcoming possibilities of James Webb Space Telescopewhich is very suitable for observations of weaker targets. ”
Observing stars in mid-infrared light is the best way to directly monitor dust emissions around them, Levesque said, because it can help create a picture with many waves of massive stars and their evolution. Ultimately, weight loss and dust production play a key role in the star’s red supergiant stage.
“The average infrared frequency has also been difficult to monitor in the past,” she said, adding that NASA would soon be decommissioned. SOFIA the aerial observatory filled the gap, while JWST will soon become an invaluable medium infrared resource. “Combined with creative solutions like the ones presented in this article, we hope to continue to build a much clearer picture of the red supergiants in this wavelength range in the coming years.
The authors have already begun using Himawari-8 data for other stellar projects. “I believe that our concept of using a meteorological satellite as a space telescope is useful for several types of topics in astronomy, especially stellar astrophysics in the time domain,” Taniguchi said, referring to the emerging field focused on how astronomical objects change. over time. . His team is now using data from Himawari-8 to make a catalog of how older stars vary in infrared brightness over time, as well as to search for fleeting infrared signals.
About 548 light years from us (opens in a new section), Betelgeuse is the closest red supergiant star to the solar system. It is about 15 to 20 times the mass of the sun and about 900 times larger. If the giant were at the center of our solar system, then Mercury, Venus, Earth, Mars, and the asteroid belt would be inside Betelgeuse.
And every time Betelgeuse becomes a supernova, it can glow brightly like a full moon for several months. The end result will be a neutron star in the center of a beautiful balloon of luminous material created by the explosion. However, scientists still do not know exactly how a red supergiant behaves in the weeks before it explodes.
The study is described in a paper (opens in a new section), published Monday (May 30th) in the journal Nature Astronomy.
Jamie Carter is the author of “Star Tracking Program for Beginners (opens in a new section) “(Springer, 2015) and he edited WhenIsTheNextEclipse.com. Follow him on Twitter @jamieacarter. Follow us on Twitter @Spacedotcom or on Facebook.
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