Today's object is one of the stars in the constellation Cetus. People who have listened to my previous podcasts will know that I think this constellation is stupid because it's supposed to look like a whale or sea monster or something but doesn't, but for new listeners, I'll just say that this constellation is stupid because it's supposed to look like a whale or sea monster or something but doesn't.
The specific star that this episode's coordinates point to is Beta Ceti, also known as Diphda, which is not actually stupid at all but actually kind of interesting. First of all, this star is an evolved giant star that might have formed from something slightly larger than the Sun. Stars start their lives fusing hydrogen into helium in their cores, but when their cores fill up with helium, they start going through a series of evolutionary changes. The first change involves the stars fusing hydrogen into helium in shells around the helium cores and expanding into red giants. Beta Ceti is at a stage after that point where the pressure in its core is sufficiently high that it can fuse helium into carbon and oxygen for energy.
In plots where stars' temperatures are on the x-axis and stars' luminoisities are on the y-axis, Beta Ceti would lie in a place where evolved stars make a straight horizontal line, so they are called horizontal branch stars. However, many of these stars, including Beta Ceti, tend to bunch up in one place on this line, and this subset of stars are called red clump stars.
The distance to Beta Ceti is 96.2 light years (29.5 pc) [1], which means that it's relatively close, although not close enough that I can use my Star Wars sound effects. This, along with the fact that Beta Ceti is a giant, makes it relatively bright in the night sky; it has an apparent magnitude of about 2 [2], making it visible to the naked eye. Additionally, it's a single star, which means that nothing messy is happening involving interactions between it and another star orbiting it. Consequently, these properties make Beta Ceti a good star to study to understand evolved horizontal branch stars more generally.
However, this star is a bit peculiar in a couple of ways. Most importantly, it seems to have unusually strong magnetic fields compared to most other stars that have reached this same point in their evolution [3, 4]. This is rather unusual, because it is unlikely that a star would keep its magnetic fields once it reaches the stage where it is fusing helium in its core. A research group led by Svetla Tsvetkova spent several years monitoring the magnetic fields in Beta Ceti, and they have concluded that it is very likely that Beta Ceti was originally part of a class of stars called Ap stars before it turned into a giant star [3, 4]. Ap stars are stars that fuse hydrogen into helium in their centers that are technically described as "chemically peculiar". I'm going to skip over discussing the chemically peculiar part here, but what is important is that Ap stars also have abnormally strong magnetic fields, and it's possible that Beta Ceti has retained its magnetic fields despite evolving into a giant star that fuses helium in its core.
These strong magnetic fields also make Beta Ceti a little weird in a couple of other ways. First of all, the magnetic fields have led to extra flaring on the surface of the star [5]. Second Beta Ceti is abnormally bright in X-ray emission compared to other helium-fusing stars [6]. It's a truly unusual object which I think, in years to come, will continue to pique the interests of a small group of astronomers interested in weird stellar phenomena.
So, as I stated before, Beta Ceti is visible to the naked eye, so you too can go see it in the night sky. However, as I also stated before, Cetus does not actually look like a whale or sea monster, and in fact, the constellation doesn't look like much of anything, so it will be challenging describing the location of Beta Ceti. The constellation Cetus could be described as two irregularly-shaped polygons connected by a line of stars. Beta Ceti is located in the southwest corner of the polygon in the southwest part of the constellation, and it should be the brightest star in this area of the sky. Also, I'm not going to recommend looking at this with a telescope; it will just look like a bright dot.