Tuesday, June 18

Nearly 50% Brighter Betelgeuse. What Happens? 2023

Whenever Betelgeuse does something, supernova rumors spread. If so, awesome. It’s exciting to visualize the sky lighting up for months because we’re far away.

The red supergiant star has brightened roughly 50%, reviving suspicions.

Supernova Betelgeuse. All agree. When is uncertain. Star behavior puzzles. How can puny people learn?

Betelgeuse is a red supergiant and pulsing semiregular variable star. Though amplitudes vary, its brightness variations are periodic. Brightness varies every 400 days. Pulsations also govern its 125-day, 230-day, and 2200-day cycles. Those cycles might make the star confusing.

People asked why Betelgeuse darkened two years ago. Star brightness did not change. Instead, the star released surface material that cooled into a dust cloud and obscured the light. “The Great Dimming” is the episode.

Since it’s brightening, scientists are again interested. They want to know its evolutionary stage and what all this activity means. New study suggests it might supernova sooner than thought.

“The evolutionary stage of Betelgeuse inferred from its pulsation periods” is the new paper. Tohoku University’s Astronomical Institute, Graduate School of Science, first author Hideyuki Saio. The Royal Astronomy Society Monthly Notices published the work.

New research’s juicy bits make headlines

Dr. Eldridge isn’t targeted. She’s right. The paper states just one outcome. It lists others.

The authors think Betelgeuse might be the Milky Way’s next supernova regardless of their results. “Betelgeuse is in the late stage of core carbon burning and a good candidate for the next Galactic supernova,” they write.

Red supergiant Betelgeuse exited the main sequence. For 8 to 8.5 million years, it fused hydrogen into helium and released the mass as energy. Thanks Einstein. It no longer fuses hydrogen into helium like the Sun. When stars lose mass, they expand into a larger envelope. They grow while losing bodyweight.

After stars like Betelgeuse depart the main sequence and stop fusing hydrogen into helium, everything changes. Their cores accumulate carbon during helium fusion. They then burn core carbon to make other elements. The new article claims Betelgeuse is in its late stages.

How late? How long? That’s still unknown.

“Despite the relatively small distance from Earth, and in some sense because of it, it has been difficult to obtain tight constraints on the distance, luminosity, radius, current and Zero Age Main Sequence (ZAMS) masses, and information about the internal rotational state and associated mixing and hence on the evolutionary state of Betelgeuse and when it might explode,” write the authors of a new review. ZAMS is very important for star development. It’s crucial but not exclusively responsible.

The analysis suggests viable options.

The work combines observations and hypotheses that fit the observations differently. It’s complicated, so headlines or Tweets saying it might erupt in tens of years are inaccurate. Nuance seldom attracts.

Core carbon-burning comprises multiple phases. Determining whatever stage Betelgeuse is in makes supernova prediction tricky. Betelgeuse pulses, ejects, spins, and is a runaway star.

Its distance from us is debatable. “Although it lies only ~200 parsecs from Earth, and hence can be spatially resolved with appropriate instrumentation, uncertainties in its distance remain a critical impediment to deeper understanding,” the Betelgeuse review said.

Leave a Reply