Did Betelgeuse Swallow Its Companion?

Someday soon, the shoulder star of Orion, Betelgeuse is going to explode as a supernova. The article from Skyandtelescope, “Did Betelgeuse Swallow Its Companion?” by Kelly Beatty explains for a normal star, astronomers can get a good estimate when that explosion would occur. Unfortunately Betelgeuse is not a normal star, and everything known about this star is uncertain, including its surface temperature, mass and even its distance aren’t of certain. In order to find out when Betelgeuse will explode, scientists need to have all this information pinned down. Betelgeuse is believed to have a mass 19 times larger than our sun’s, with 126,000 times its energy output and a diameter of at least  1.2 billion kilometers. Another issue with Betelgeuse is that it is spinning abnormally fast at 15 km/s while our sun spins at only 2 km/s. This usually occurs when stars are within the last 1,000 years of their lifespan. The issue with this is that Betelgeuse is only about 8 million years old and scientists can’t see a star like this die off so soon. J Craig Wheeler a supernova specialist theorizes that Betelgeuse formed as a part of  a binary system and “ate” its companion star while it swelled up to its current size. The next step for the Betelgeuse project is to use a technique called Asteroseismology which probes the star’s interior and can reveal any dense, undissolved remnant of the star that Betelgeuse may have eaten.

I found this article to be a bit surprising. Going through this semester, I have read so much about scientists known mass and distance and temperature of so many stars and planets and other objects, but Betelgeuse which is a very well known star, they can’t figure out exact information on it. I am curious to what makes Betelgeuse that much different to other stars that scientists can’t find out this information. Although this article was an interesting topic I found it to be lacking in information. For instance, it mentions that Betelgeuse is spinning too fast and that it might be from it destroying another star. However, it doesn’t mention how or why “eating” another star would cause it to spin faster. It leaves the reader (me) with a lot of questions, such as will Betelgeuse explode sooner than its average life expectancy due to the faster spinning, or will it eventually slow down after it settles after the destruction of the other star. Despite the lack of detail, This article relates to our 14th conceptual objective. Eventually, all stars die, usually after several million years. As stars age, radiation pressure around their core begins to expand, from this their surface temperature lowers due to it being further away from the core. When this happens, the star is turning into a red giant. A star’s mass determines what happens after it becomes a red giant. From “Stellar Evolution” in our Lecture Tutorial notes, I learned there are two categories of stars; Low-mass and High-mass.

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A low-mass star, which is less than 8 times the mass of our sun, breaks away its outer layers to produce a planetary nebula. In the center of this planetary nebular, The stellar core remaining is known as a white dwarf. On the other hand, a star that has a mass greater than 8 times the sun’s, will explode into a supernova. The supernova blasts away all the remnants of the star just leaving a core called a neutron star. These stars are very small and very dense, usually smaller than Earth’s moon. If the star’s mass was extremely large, instead of a neutron star, a black hole is formed due to the amount of pressure. The article states that Betelgeuse is estimated to be about 19 times the mass of our sun. This means that Betelgeuse will form a supernova and may only be left as a small neutron star. However if its mass is great enough, Betelgeuse will form a black hole once it explodes.

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