The Astonishing Brightening of Betelgeuse
One of the most captivating celestial objects in our galaxy, Betelgeuse, has lately been shining nearly 50% brighter than usual. This celestial spectacle often sparks a wave of speculative frenzy, primarily around the possibility of it exploding into a supernova. This scenario, while quite dramatic, is quite harmless for us given our safe distance from the star. It indeed fuels our imagination about how the sky would look lit up by such a cosmic spectacle for several months.
Delving into the Behavior
While it is universally agreed that Betelgeuse is bound to explode into a supernova, the uncertainty lies in predicting the timeline of this stellar event. This red supergiant star’s behavior is puzzling and enigmatic, posing a challenge for us humans to comprehend. Betelgeuse, in addition to being a red supergiant, is also a pulsating semiregular variable star, indicating that its brightness undergoes periodic changes. Its brightness fluctuations are characterized by several cycles, including a major 400-day cycle, a 125-day cycle, a 230-day cycle, and an astounding 2,200-day cycle. All these cycles are driven by pulsations, adding to the complexity in understanding the star.
The Great Dimming
Brightness history has seen some intriguing twists. A few years back, it experienced a significant dimming that sparked curiosity and speculation. However, a fascinating discovery revealed that the star’s brightness hadn’t actually changed. Instead, the dimming was an optical illusion caused by the star ejecting material from its surface, which subsequently cooled into a dust cloud, obscuring the light emanating from the star. This phenomenon has since been dubbed “The Great Dimming.”
Deciphering BG Evolutionary Stage
With Betelgeuse exhibiting a recent brightening, the interest among the scientific community is renewed. Researchers are keen to understand the evolutionary stage the star is currently in and what the enhanced activity might signify. New findings hint that Betelgeuse might explode as a supernova sooner than anticipated. The recent study, led by Hideyuki Saio from Tohoku University in Japan, explores the evolutionary stage of Betelgeuse and its possible outcomes. The authors propose that Betelgeuse could potentially be the next supernova in our Milky Way galaxy, given its late stage of core carbon burning.
BG Stellar Journey: From Main Sequence to Red Supergiant
Betelgeuse has led a remarkable existence over the span of approximately 8 to 8.5 million years. Initially a main sequence star, it utilized a significant amount of hydrogen, converting it into helium and releasing energy in the process. Consequently, it transitioned into a red supergiant, no longer fusing hydrogen into helium like the sun. The loss of mass, coupled with the inability of gravity to contain the outward pressure, resulted in BG expanding into a voluminous envelope, thus growing in size despite the mass loss.
A Conundrum in the Cosmos
Following the main sequence phase, stars like BG enter a helium fusion stage, which significantly alters their behavior. During this phase, a buildup of carbon occurs in their cores. Subsequently, they embark on a core carbon-burning period, leading to the production of other elements. While BG is believed to be in the late stages of this period, the exact timeline remains elusive. Factors such as distance, luminosity, current and Zero Age Main Sequence (ZAMS) masses, and internal rotational state play crucial roles in understanding the star’s evolutionary state and predicting its explosion. However, they are challenging to accurately determine.
A Glimpse into Core
The core carbon-burning period is a complex phase with several stages. The challenge in determining when Betelgeuse will go supernova stems from identifying which of these stages it is currently in. Factors such as BG pulsations, ejected material, rotation, speed through space, and disputed distance from us, add to the complexity. The research paper suggests Betelgeuse could explode as a supernova sooner than expected, but there’s no concrete evidence supporting this claim as the exact stage of core carbon-burning is undetermined. This discrepancy leads to various contrasting theories regarding Betelgeuse’s evolutionary phase.
Predicting Betelgeuse’s Spectacular End
The unanimous consensus is that BG is destined to explode as a supernova. However, unlike some supernovae, it is not anticipated to produce a lethal gamma-ray burst. The explosion will emit material and produce potent X-ray and UV radiation, but given our safe distance from the star, we would not be affected. Instead, the spectacle would be a breathtaking light show visible to all of humanity, permanently altering the Orion constellation. The ensuing research and observations would provide a wealth of data, offering unprecedented insights into stellar evolution, supernovae, and stellar remnants.
The Impact of Betelgeuse’s Supernova on Earth
While the shock wave from the supernova would reach Earth in about 100,000 years, it would be easily deflected by our sun’s solar magnetosphere. The most noticeable impact on Earth would be an increase in cosmic rays hitting our upper atmosphere. This cosmic event would certainly capture the collective awe of humanity, though it might also give rise to bizarre conspiracy theories or pseudo-religious, cult-like reverence. That is, of course, if humanity is still around when the stellar spectacle occurs.
Read Orginal Article: https://phys.org/news/2023-06-betelgeuse-brighter.html