Discovery suggests red supergiant Betelgeuse was actually yellow 2000 years ago

By | 07/09/2022
Red Giant Betelgeuse was yellow some 2,000 years ago
The constellation Orion, Betelgeuse is marked with Blastoff. Credit: Markus Mugrauer

An interdisciplinary squad centered around a Jena astrophysicist utilized observations from artifact to prove that Betelgeuse—the bright red behemothic star in the upper left of the constellation Orion—was xanthous-orange some 2,000 years ago.

As nuclear fusion in the eye of a star progresses, effulgence, size, and colour also change. Astrophysicists tin derive from such properties important information on the age and mass of a star. Those stars with significantly more mass than our sun are blue-white or red—the transition from scarlet to xanthous and orange is relatively rapid for astronomical time-scales.

Astrophysicists of Friedrich Schiller Academy Jena, Federal republic of germany, together with colleagues of other subjects from the U.S. and Italian republic, have now successfully detected and dated such a color change in a bright star. With several historical sources, they found that Betelgeuse—the brilliant reddish behemothic star in the upper left of the constellation Orion—was yellow-orange some 2,000 years ago. They report nigh their results in the current issue of
Monthly Notices of the Royal Astronomical Gild.

Sources from antiquity from effectually the earth

The Chinese courtroom astronomer Sima Qian wrote around 100 BC nigh star colors: white is like Sirius, red like Antares, yellow like Betelgeuse, blue like Bellatrix. “From these specifications, one can conclude that Betelgeuse at that time was in color betwixt the blueish-white Sirius and Bellatrix and the red Antares,” says Prof. Ralph Neuhäuser from the Academy of Jena.

Independent from the above, the Roman scholar Hyginus described some 100 years afterwards that Betelgeuse was in color similar the xanthous-orange Saturn—thus, one can quantify the quondam color of Betelgeuse with even more precision.

Additional authors from antiquity like Ptolemy bring further indications that Betelgeuse at their time did non belong to the group of vivid ruddy stars like Antares (in the constellation Scorpion) and Aldebaran (in Taurus, the Bull).

The Greek name Antares means “like Mars” in color; it was indeed reported every bit ruddy and compared to Mars since millennia from cultures around the globe. “From a statement by the Danish astronomer Tycho Brahe, i can conclude that, in the 16th century, Betelgeuse was more blood-red than Aldebaran,” Neuhäuser notes. Today, Betelgeuse is comparable in brightness and color to Antares.

Notwithstanding 1.v meg years to become until Betelgeuse explodes as supernova

Astronomer Ralph Neuhäuser from Jena has included historical celestial observations in his astrophysical enquiry for the past ten years—this field is chosen “Terra-Astronomy.” He closely collaborates with colleagues from languages, history, and natural philosophy—including his married woman Dagmar. “The view dorsum in fourth dimension delivers strong impulses and important results,” Neuhäuser adds. “At that place are quite a number of astrophysical problems which can hardly be solved without historical observations.”

What do those historical transmissions tell the states almost Betelgeuse? “The very fact that information technology inverse in color within two millennia from yellowish-orange to red tells usa, together with theoretical calculations, that it has 14 times the mass of our sun—and the mass is the master parameter defining the evolution of stars,” Neuhäuser explains. “Betelgeuse is now 14 million years old and in its late evolutionary phases. In well-nigh 1.5 one thousand thousand years, it will finally explode equally supernova.”



More than information:
R Neuhäuser et al, Colour evolution of Betelgeuse and Antares over two millennia, derived from historical records, as a new constraint on mass and historic period,
Monthly Notices of the Purple Astronomical Gild
(2022). DOI: 10.1093/mnras/stac1969

Provided by Friedrich-Schiller-Universität Jena

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