Leo is a nice spring constellation. During April and into May, it appears right overhead in the southern sky a few hours after the sun goes down, so it is hard to avoid it – you don’t have to stay up late or get up early. It also contains the 22nd brightest star in the sky, not including our Sun, Regulus. Regulus means “prince” or “little king,” but there’s more to this bright neighbor whose light reaches our eyes 77 years after it left the star.
Binary stars are stars that are either gravitationally bound to each other (so they’re close to each other) or that look like they travel together from our perspective on Earth. In many cases, the human eye can’t tell that there are two dots of light, we only see one when we look at the star. But our Time Machine can gather much more light than the human eye, and can magnify that light so we can see what else there might be.
In the case of Regulus, it is a binary pair of binary pairs. That’s right, there are four stars that make up what we see as Regulus. The main star (Regulus A) is a big blue-white hot star. It’s orbited by a very teensy tiny star that we can’t see directly because it’s so small and gets lost in the glare of Regulus A. Both of these stars are in turn orbited by two smaller stars also in orbit of each other, Regulus B and Regulus C. They’re too small to see independently from each other, but Regulus A and Regulus B/C can be split or resolved in two their component pieces in a good Time Machine.
Luckily, Astropotamus has a good Time Machine. The main image at the top of this post is an image of Regulus as we see it from Earth. Not as bright as it should be because Astropotamus had to shrink the image to fit in the title of this post. It’s the middle image in the gallery below. In addition, there are two others: the first image is of the full sky near Regulus, and the last image is a close of up Regulus A that let’s you see Regulus A plus Regulus B/C split into their separate components.
This splitting or resolving of binary stars is sometimes used as a good judge of the quality of a Time Machine, since really close ones can be hard to resolve. Why is it called splitting? Well, you’re “splitting” a pair of stars into two separate ones. Why is it called resolving? Just like you use the word “resolution” to determine how much information is in a digital picture, the word “resolve” has the same root. So “resolving” something through a Time Machine means you are able to have enough “resolution” to make out the difference between the two objects.
These images were taken with a wider field of view than the moon pictures from before. Since stars are so far away, Earth-based Time Machines really don’t have the ability to magnify them enough to be anything other than larger dots of light. So we usually use less magnification to bring in more of the surrounding sky than we do with Sun, moon, or planet pictures. As you’ll see tomorrow, it lets us peer very closely at a large piece of sky that way.