Betelgeuse, also known as Alpha Orionis or Alpha Ori, is the second closest red supergiant star to Earth. From November 2019 to March 2020, the star experienced a historic diminution in visible brightness. Its apparent magnitude is usually between 0.1 and 1, but around February 7-13, 2020, its visual brightness decreased to magnitude 1.6. This event is called the Great Fading of Betelgeuse. A new study shows that the observed dimming is probably caused by an invisible companion star orbiting Betelgeuse. The companion, named Alpha Ori B, or Betelbuddy, acts like a snowplow as it orbits Betelgeuse, pushing light-blocking dust out of the way and making Betelgeuse appear temporarily brighter.
Graphic depiction of Betelgeuse and Betel Buddy. Image credit: Lucy Reading-Ikanda/Simons Foundation.
Betelgeuse, the second brightest star in the constellation Orion, is an 8 million-year-old red supergiant star about 724 light-years from Earth.
With a radius about 1,400 times larger than the Sun, Betelgeuse is one of the largest known stars.
It is also one of the brightest stars known, emitting more light than 100,000 suns.
The star is nearing the end of its life, and when it explodes, the event will be bright enough to be visible during the day for several weeks.
Astronomers can predict when Betelgeuse will explode by effectively “checking the pulse.”
This is a variable star, meaning it brightens and dims, pulsating like a heartbeat.
Betelgeuse has two heartbeats. One pulsates on a timescale of slightly longer than a year, and the other on a timescale of about 6 years.
One of these heartbeats is Betelgeuse's fundamental mode, a pattern of brightening and dimming unique to the star itself.
If a star's fundamental mode is its long-scale pulse, Betelgeuse could be ready to explode sooner than expected.
However, if the fundamental mode is that short-scale heartbeat, as some studies have suggested, then that longer heartbeat is a phenomenon called long secondary period.
In that case, this long brightening and dimming would be caused by something outside the star.
Scientists still don't know exactly what causes the long secondary period, but one leading theory is that the star has a companion star orbiting it and flying through the cosmic dust produced and ejected by the star. A secondary period occurs when the
The displaced dust changes the amount of starlight that reaches Earth, changing the star's apparent brightness.
Astrophysicist Jared Goldberg of the Flatiron Institute and his colleagues are investigating whether other processes, such as stirring inside the star or periodic changes in the star's strong magnetic field, could have caused the long secondary periods. was investigated.
After combining data from direct observations of Betelgeuse with sophisticated computer models that simulate the star's activity, the researchers concluded that Betelgeuse was the most likely explanation.
“We've eliminated all possible inherent variables as to why it brightens and dims the way it does,” Dr. Goldberg said.
“The only hypothesis that seems compatible is that Betelgeuse has a companion star.”
The authors have not yet determined exactly what Betelbadi is, but they assume it is a star with up to twice the mass of the Sun.
“Other than giving us constraints on mass and orbit, it's hard to say what the companion star actually is,” said Dr. Meridith Joyce, an astronomer at the University of Wyoming.
“A Sun-like star is the most likely type of companion star, but it's not definitive.”
Next, the team will try to take images of Bethelvadi with telescopes, as visibility may open around December 6, 2024.
“Since our results are based on inference rather than direct detection, we need to confirm that Betelbadi actually exists,” said Dr. László Molnár, an astronomer at the Konkoli Observatory.
“So we are currently working on an observation proposal.”
of findings will appear in astrophysical journal.
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Jared A. Goldberg others. 2024. Betelgeuse's companion: Binary stardom as the origin of Alpha Orionis' long secondary period. APJin press. arXiv: 2408.09089
Source: www.sci.news
