Astronomers have a new way to study stars: using meteorological satellites orbiting the Earth.
This is the conclusion of a new document that presents new data from a Japanese meteorological satellite that just happened to observe a red giant star. Betelgeuse during periods of unexplained twilight. Random observations could be a new tool for astronomers trying to understand how a red giant star loses mass and eventually explodes like a star. supernova.
The second brightest star in constellation Orion, Betelgeuse (pronounced “bet-orl-gerz” or “beetlejuice”) is the 10th brightest star in the night sky. However, from October 2019 to February 2020, it dimmed dramatically to about two-thirds of normal brightness. This so-called “big twilight” event has led to speculation that it was about to explode as a type IIP supernova, which is sure to happen over the next 100,000 years.
Related: Orion and his twilight star Betelgeuse in this sentimental photo of the night sky shine above the star watcher
The scientists analyzing the event used mostly data from ground-based optical telescopes. Astronomers have mostly concluded that the dimming of Betelgeus was the result of either its surface cooling, the new band of dust that had formed around it, or both.
Ground-based telescopes cannot see through dust and gas in space, which requires infrared vision. That’s Because Earth’s atmosphere it blocks infrared radiation, as well as X-rays, gamma rays, and most ultraviolet rays. Thus, only space observatories can see infrared light – including meteorological satellites such as Himawari-8 (opens in a new tab)one of the geostationary meteorological satellites of the Japan Meteorological Agency.
And the astrophysical debut of Himawari-8 began in an unlikely place: on Twitter.
“We saw a tweet that said there was a moon in his pictures,” said Daisuke Taniguchi, Ph.D. an astronomy student at the University of Tokyo and the first author of the article, Space.com said. “I talked to [third author] Shinsuke Uno found that Betelgeuse was in the field of view of Himawari-8 about the use of meteorological satellites for astronomy, and realized that perhaps the Great Twilight of Betelgeuse could be explored. “
Since 2015, Himawari-8 has been located 22,236 miles (35,786 kilometers) above the Earth’s equator to study weather and natural disasters (including Hunga Tonga-Hunga Haʻapai volcano eruption on 15 January). Although there is a satellite up there to show the Earth every 10 minutes, the edges of its images include stars.
Taniguchi and colleagues were able to see Betelgeuse in lifetime Himawari-8 images and measured its brightness approximately every 1.7 days between January 2017 and June 2021. And the Advanced Himawari Imager (AHI) satellite studied Betelgeuse in two ways.
“In the optical and near-infrared wavelength ranges, circumstellar dust obscures light from the star’s surface,” Taniguchi said, explaining that researchers – like astronomers restricted to the use of terrestrial telescopes – were able to estimate the amount of circumstellar dust around Betelgeuz.
However, circumstellar dust emits only mid-infrared light. “By observing such mid-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 twilight” of 2019 and 2020 was caused by two factors in almost equal proportions: the star’s temperature dropped by about 250 degrees Fahrenheit (140 degrees Celsius) and the dust condensed from the warm gas around the star.
Crucially, this theory is broadly in line with what astronomers using ground-based telescopes have arrived at. For example, a study led by the Chinese Academy of Sciences cited a giant sunspots and temperature fluctuations while Result from the Very Large Telescope of the European Southern Observatory in Chile and from the Hubble Space Telescope suggested Betelgeuse ejected a huge cloud of gas, which cooled and condensed to dust.
New findings from scientists suggest that meteorological satellites could be used as space telescopes for astronomy. “It allows us to obtain high-cadence time series of mid-infrared images that are difficult to obtain using conventional astronomical instruments,” the document said. In addition to the fact that ground-based telescopes are unable to record data from near-infrared radiation, some stars lose sight of them for several months as the Sun moves in front of them.
“This is an opportunity I haven’t seen much before,” said Space Emily Levesque, author of The Last Stargazers and a red-giant astronomer at the University of Washington who did not participate in the new research. com.
“It certainly depends in part on chance, but observations like this could prove to be a great source for bright nearby red supergiants,” she said. “Especially since they could complement the upcoming capabilities James Webb Space Telescopewhich is well suited for observing weaker targets. ”
Observing stars in the mid-infrared region is the best means of directly observing the emission of dust around them, Levesque noted, because it can help create an image of massive stars and their evolution at multiple wavelengths. After all, mass loss and dust production play a key role in the stellar red giant stage.
“Mid-infrared radiation has historically been difficult to observe,” she said, adding that NASA will soon decommission SOFIE the air observatory has filled the gap, while the JWST will soon become an invaluable source of mid-infrared radiation. “Combined with creative solutions like the ones presented in this paper, we hope to continue to create a much clearer view of red supergiants in this wavelength range in the coming years.”
The authors have already started 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 astrophysics of time-domain stars,” Taniguchi said, referring to an emerging area focused on how astronomical objects change over time. . His group now uses Himawari-8 data to create a catalog of how older stars change in infrared brightness over time, as well as to search for volatile infrared signals.
Approximately 548 light-years away (opens in a new tab), Betelgeuse is the closest red giant to the solar system. It is about 15 to 20 times the mass of the Sun and about 900 times greater. 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 whenever Betelgeuse becomes a supernova, several months can shine bright like a full moon. The end result will be a neutron star at the center of a beautiful bubble of glowing material created by the explosion. However, scientists do not yet know exactly how the red giant behaves in the weeks before the explosion.
The research is described in paper (opens in a new tab) published on Monday (May 30) in the journal Nature Astronomy.
Jamie Carter is the author of “Star observation program for beginners (opens in a new tab)(Springer, 2015) and edits WhenIsTheNextEclipse.com. Follow him on Twitter @jamieacarter. Follow us on Twitter @Spacedotcom or on Facebook.
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