The Spectacular Event of a Betelgeuse Supernova

Introduction

Supernova explosions are among the most exciting events in the universe for astronomers and stargazers. These cosmic fireworks mark the dramatic end of a star's life, releasing an incredible burst of light and energy that can outshine entire galaxies. Among the stars that might give us this spectacular show is Betelgeuse, a red supergiant in the constellation Orion. Because of its immense size, brightness, and mysterious behavior in recent years, astronomers believe it will undergo an explosion in the near future.

This article delves into what exactly a supernova is, explaining the different types of these stellar explosions and how they occur, what kind of star Betelgeuse is, and finally, what Betelgeuse's supernova explosion would look like from our perspective on Earth and what it would mean for both the scientific community and the general public.

What is a Supernova?

A supernova is an event that happens when a star dies by exploding. This explosion is extremely bright and releases a lot of light and energy. There are two broad types of supernovas - Type I and Type II. These two types are further divided into more specific sub-types. Supernova types vary due to distinct astrophysical processes, helping astronomers understand star life cycles and explosion mechanisms.

A table with all the supernova types and their sub-types.

Type I Supernova

Characteristics: Lacks hydrogen.

Subtypes:

• Type Ia: Occurs in a binary system where a white dwarf accretes matter from a companion star. This type of supernova happens when a star evolves into a white dwarf, which then accretes material from its companion star. When the white dwarf reaches a critical mass, it undergoes a runaway fusion reaction, resulting in a supernova explosion. Type Ia supernovae don't have hydrogen in their outer layers because they've already lost it.
• Type Ib/Ic: This happens in giant stars. Before exploding, these stars have already lost their outer hydrogen layers (Type Ib) or both their hydrogen and helium layers (Type Ic). This can happen because of strong winds from the star or because it is close to another star. Type Ib supernovae still have helium, while Type Ic supernovae have lost both hydrogen and helium.

Type II Supernova

Characteristics: Has hydrogen.

Type II supernovae happen in massive stars at least eight times the size of our Sun. These stars explode when they run out of fuel.  The star's core collapses when this happens, and the outer layers blast away in a massive explosion. Type II supernovas still have hydrogen in their outer layers.

Subtypes:

Type II supernovas are further divided into specific sub-categories that differ slightly, but they aren't usually mentioned when discussing supernova types broadly and are not as common in the cosmos.

Betelgeuse: A Red Supergiant

Betelgeuse is one of the largest and brightest stars visible to the naked eye. This red supergiant star is about 700 light-years from Earth in the constellation Orion. You can easily spot it as one of the "shoulders" of the hunter figure in this constellation.

Betelgeuse is a star of enormous size, approximately 1,400 times the diameter of our Sun. If it were at the center of our solar system, it would extend beyond Jupiter's orbit.

One of the most intriguing aspects of Betelgeuse is its relative closeness to Earth and its changing brightness. Unlike most stars, which stay the same brightness, Betelgeuse gets dimmer and brighter over time. This changing brightness has fascinated astronomers for a long time.

In recent years, Betelgeuse's brightness has been changing in unusual ways. Because of this, astronomers think Betelgeuse is getting close to the end of its life, which means it might explode as a supernova soon. The event is inevitable due to Betelgeuse's stage in stellar evolution, although the exact timing is uncertain and could occur anywhere from tomorrow to 100,000 years from now.

Betelgeuse changes in brightness as seen through a telescope from Earth.

Betelgeuse Over the Centuries

Astronomers have long been fascinated by and studied Betelgeuse. Ancient civilizations, like the Egyptians and Greeks, noticed it in the night sky and often gave it mythological meanings because of its bright and changing appearance.

Interestingly, some ancient texts like De Astronomica describe Betelgeuse as similar in color to Saturn rather than Mars, which would be more logical looking at its color now. "The Almagest," written a century later, lists Antares among the brightest red stars but does not mention Betelgeuse. Additionally, Sima Qian, a Chinese archivist from the 1st to 2nd century BC, described Antares as a red star and Betelgeuse as a yellow star.

Comparing ancient texts shows that Betelgeuse has changed color over time through its life cycle. This highlights how the star has evolved.

A page from De Astronomica shows the Orion constellation with Betelgeuse located in the hunter's shoulder. Source: Bavarian State Library, World Digital Library.

Astronomers systematically observed Betelgeuse in the 19th century, documenting its unusual brightness fluctuations. In the 1920s, the star was one of the first to have its diameter measured using interferometry, revealing its massive size compared to our Sun.

What Would a Betelgeuse Supernova Look Like?

When Betelgeuse eventually goes supernova, astronomers predict that it will be an incredible sight to behold. The explosion will be so bright that it could outshine the full moon, making it visible even during the day. This spectacular event will dominate the night sky for weeks to months, offering a once-in-a-lifetime experience for people on Earth.

The explosion will likely produce a dazzling light show with changing colors and intensities as the star's outer layers blow away into space. The brightness will gradually fade, but the remnants of the supernova could still be visible for years to come. They will eventually form a nebula, a beautiful cloud of gas and dust illuminated by the leftover core of the star.

Comparison With Other Supernovae

Comparing Betelgeuse's potential supernova to past supernovae can help us understand the scale and impact of such an event. For instance, SN 1987A, a supernova observed in the Large Magellanic Cloud in 1987, provided significant insights into stellar explosions' mechanics and aftereffects.

However, Betelgeuse is much closer to Earth, so its explosion would be much brighter and easier to see. Another example is the Crab Nebula, which is the leftover of a supernova that happened in 1054 AD and was visible during the day for weeks. Betelgeuse's supernova could be even more impressive, lighting up the night sky for months.

Animation combining photos of Crab Nebulas radio, infrared, optical, ultraviolet, and x-ray light from five observatories.

Scientific Significance

The explosion of Betelgeuse would offer scientists a rare opportunity to study a supernova in detail. Observations from telescopes worldwide and in space would provide valuable data on the workings of stellar explosions, the distribution of heavy elements, and the behavior of shock waves. They could also enhance our understanding of neutrinos and gravitational waves, which are expected to be produced in large quantities during the explosion.

Impact on Earth

Even though a Betelgeuse supernova would be dramatic to watch, it wouldn't be dangerous to life on Earth. The star is far enough away that the radiation and particles wouldn't harm us. Instead, it would be a spectacular natural event, inspiring new astronomers and capturing the public's interest.

Conclusion

1. Betelgeuse's supernova would be an extraordinary event, brighter than the full moon and even visible during the day.
2. Betelgeuse has captivated astronomers for centuries due to its size, brightness, and changing behavior. Ancient texts and modern observations highlight its evolution, including changes in color and brightness over time.
3. There are three types of supernovae - Type Ia, Type II, and Type Ib/Ic - each with distinct characteristics and causes.
4. Watching the Betelgeuse supernova would give us important information about how stars explode, spread heavy elements, and create shock waves, neutrinos, and gravitational waves.
5. Even though Betelgeuse's supernova would look dramatic, it wouldn't be dangerous to Earth because the star is far away from us. It would be a safe and exciting learning experience for everyone.
6. The timing of Betelgeuse's explosion is uncertain and could range from tomorrow to 100,000 years from now.

References

1. Neuhäuser, R; Torres, G; Mugrauer, M; Neuhäuser, D L; Chapman, J; Luge, D; Cosci, M (October 2022). "Colour evolution of Betelgeuse and Antares over two millennia, derived from historical records, as a new constraint on mass and age". Monthly Notices of the Royal Astronomical Society. 516 (1): 693–719.
2. Joyce, Meridith; Leung, Shing-Chi; Molnár, László; Ireland, Michael; Kobayashi, Chiaki; Nomoto, Ken'Ichi (2020). "Standing on the Shoulders of Giants: New Mass and Distance Estimates for Betelgeuse through Combined Evolutionary, Asteroseismic, and Hydrodynamic Simulations with MESA". The Astrophysical Journal. 902 (1): 63.
3. Zwicky, Fritz (1 January 1940). "Types of Novae". Reviews of Modern Physics. 12 (1): 66–85.
4. Murdin, P.; Murdin, L. (1978). Supernovae. New York, New York: Press Syndicate of the University of Cambridge.
5. NASA - "What is Betelgeuse? Inside the Strange, Volatile Star"