Artist’s concept of a Hypergiant Star. Hypergiant stars are the most massive known. They can weigh … [+]
RW Cephei is one of the largest stars known to humanity, a red hypergiant thought to be over a thousand times wider than our own sun.
But now it appears to be going through what some astronomers are calling a “great dimming” event similar to what we saw with Betelgeuse a few years back that led to some speculation the bright star might be on the verge of a supernova explosion.
“The star is significantly dimming, instead of rebrightening,” reads an Astronomers’s Telegram notice from a pair of European sky watchers, Wolfgang Vollman and Costantino Sigismondi. “This phenomenon undergoing on RW Cep might be similar to the one occurred to the red supergiant Betelgeuse at the end of 2019.”
Supergiant and hypergiant stars like Betelgeuse and RW Cephei, respectively, are among the largest stars known. They are typically thought to be at a phase of stellar evolution where they have expanded almost to the point of instability, at which point they will collapse and likely trigger a supernova explosion.
When significant dimming was observed in Betelguese in 2019, some began to wonder if we might be seeing the beginning of such a collapse. Over three years later, no such collapse has yet occurred and the giant red star is more or less back to its old self. Scientists believe the great dimming event was actually the result of Betelgeuse ejecting a massive bubble of gas.
That’s right, it was much ado about a cosmic fart.
This original shot taken by Observatoire de Paris (Paris astrological institute) shows the … [+]
This doesn’t mean we aren’t still witnessing the slow death of Betelgeuse just before a big blast, as stellar evolution events take place on long timescales.
You’ve probably heard how one day the sun will grow to actually swallow the earth and the other planets of the inner solar system, billions of years from now. This is the phase of life RW Cephei is undergoing right now. If we were to place the hypergiant star at the center of our solar system, it would stretch all the way out to the orbit of Jupiter.
It’s also important to keep in mind that most supergiant and hypergiant stars are what’s called variable stars, which means that they dim and brighten repeatedly over time. Astronomers watch these stars over the decades and keep track of what appear to be their normal cycles of dimming and re-brightening.
The dimming of Betelgeuse in 2019 and now of RW Cephei in 2022 are notable because they appear to be beyond the bounds of the normal variation in brightness for these stars.
In other words, something a little weird is happening to what is the third-largest star in the Milky Way by some measures. It could be the preface to an epic astronomical event, or it could be nothing.
Either way, professional and amateur astronomers around the world are already training their telescopes on the massive star to get a better look and possibly capture a bit of cosmic history in the making.
