When I was little, I used to look at the stars at night and wonder how many planets there are like Earth.to be Star Trek Geek, I couldn’t help but imagine a universe with fertile stars and planets everywhere. But not knowing was painful.
But this story has a happy ending. It turns out that there are many planets in the galaxy.
Even better, the story has a twist that deserves a frown from Mr. Spock (with a flat intonation of “fascinating”). Most planets that orbit distant stars (what we call exoplanets) don’t orbit anything like the Sun. Instead, the overwhelming majority revolves around red dwarfs, smaller cousins of our own stars that are the most common star-dwellers of the Milky Way.
If we find life in space, those aliens could look up (or feel/feel) a red sun in the sky instead of a yellowish-white one.
i love Star Trekbut given that the Man of Steel was born under the red sun, it looks like Superman This was right.
Astronomers discovered the first known exoplanet in the early 1990s (which is actually a pretty good story, and I encourage you to take a closer look). These are often called “pulsar planets”. However, those worlds orbit dead stars and are being fatally destroyed by high-energy radiation. It wasn’t a good thing.
Later, planets were discovered around stars that stably fused hydrogen into helium at their cores, like our own “normal” stars. But here again, nature threw us a curveball. These planets were gas giants, bloated worlds composed mostly of gas, like Jupiter and Saturn, with no solid surface to speak of. well over a thousand degrees. We call these “hot Jupiters” and they are classified as planets by anyone’s definition, but they don’t resemble Earth as much as planets do.
Eventually, astronomers discovered a planet that orbited far from its star, at the right distance, received the right amount of light and heat, and potentially had liquid water on its surface. had surface. In fact, some of these just-right planets may be smaller, Earth-like rocky planets than the typical Jupiter gas giant. Current technology can’t tell us much more than their size and mass, but we can use it to find density. This is important. Iron is much denser than rock, which is denser than water or air. Therefore, knowing the overall density of a planet allows us to know in principle whether it is similar to Earth or Jupiter. Handy.
As time went on, more such planets were discovered, updating the statistics. As we know, many of these worlds would be too hot for life, but that number was skewed because of the way the planets were discovered. Things closer to the stars are easier to find. As observational and analytical techniques improved, astronomers also discovered cooler planets, but these are still difficult to detect today.
And until recently, astronomers missed another important piece of the planetary puzzle: red dwarfs. The range of these feather-light stars is about half the mass of the Sun. They are smaller, cooler, and much darker than the Sun. Some have less than 1% brightness. Replace the Sun with a red dwarf star of that size and the Earth would solidify like Pluto.
These characteristics make learning difficult.They are dimProxima Centauri, the closest star to the Sun in the entire universe, is a pretty typical red dwarf star, but it’s so faint that you’d need a decent telescope to see it at all (and host at least two planets). is known).
But don’t confuse their weak nature with their lack of stature. They are the most common type of star in the galaxy, with more than twice as many he as all others. By comparison, the Sun is a rare behemoth, in the top 20% of stars by mass.
In 2008, the MEarth project (pronounced “maas” because astronomers can be capricious at times) was launched to study 1,200 red dwarfs with small telescopes for telltale signs of planets. . In 2009, MEarth discovered the first exoplanet, GJ1214b. It is a super-Earth (planet larger than Earth and smaller than Neptune) orbiting the nearby red dwarf star GJ1214, about 47 light-years from Earth.
Since then, more Earth-like exoplanets orbiting red dwarfs have been discovered.And in February 2023, astronomers published a new study in the journal Astronomy and Astrophysics I especially saw red dwarfs very close to the Sun. They saw three-quarters of all faint red dwarfs, or nearly 350 stars, within about 30 light-years of us. Thirty-three new planets were discovered, as well as dozens of previously discovered planets.
As an example, a particular planet discovered in a new survey is called Wolf 1069b. It orbits a very small red dwarf star with a mass one-sixth that of the Sun. The planet is probably about the same size as Earth and a little more massive. It’s encouraging.
Even better, it orbits the star at a distance of about 10 million kilometers—one fifteenth the distance from the Sun to Earth, but remember. Since the star is only about 2% as bright as the Sun, the planet gets enough heat to warm it to about minus 20 degrees Celsius. It’s chilly for sure, but that’s if there’s no atmosphere. Without air, the Earth would be about the same temperature! But our atmosphere traps heat and keeps water liquid over most of its surface. The same applies to Wolf 1069b. we don’t know
The planet is just over 30 light-years from us, meaning Earth-sized planets are common around very small red dwarfs. The galaxy is 120,000 light-years across from her, so if planets like this were rare, you wouldn’t expect them to be so close.
And this leads to the more general and, in my opinion, more awe-inspiring results of the investigation. Looking at so many stars, the average number of planets per sample star is about 1.4, and roughly 94% of the stars have planets. In other words, Nearly all red dwarfs have planets, and there are red dwarfs that tend to have multiple planets orbiting them..
This was generally known for all stars before the survey.After all, the Sun has eight planets in tow.It is easy to observe beforehand. And because of their ubiquity, this means that red dwarfs probably host more planets than all other star types in the galaxy combined! Impressive for a light bulb.
It’s nowhere near warp drive, but we’ve already compiled an impressive list of potential destinations to boldly embark on future voyages. And find out more about these planets than just find them We keep improving in discovering. Do they have vibes? air? water?
life?
At the moment, we don’t know. But until then, we will continue to boldly explore these strange new worlds.
This is an opinion and analysis article and the views expressed by the author or authors are not necessarily Scientific American.
