A team of astronomers discovered a suspected planet about the size of Neptune next to Alpha Centauri. But to be precise, it hasn't been proven to be a planet — it may just be a cloud of dust or it doesn't exist.
Please call me "CautiousLy Interested". But if it's really a planet, it's going to be a cool thing. The Alpha Centauri Galaxy is the closest galaxy to us and contains three stars, a binary system consisting of Alpha A Centauri and Alpha B Centauri, all orbits of Proxima Centauri and a faint red dwarf. Proxima Centauri has at least two stars, and there is now evidence of the existence of a third.
The binary system mentioned above is 4.37 light-years away. Alpha A Centauri is slightly larger than the Sun, warmer and brighter than the Sun, while Alpha B Centauri is slightly smaller, warmer and fainter than the Sun.
Because they are closer to us, it is easier for us to look for planets within their habitable zone (the distance to the star allows liquid water to exist on the planet's surface). For distant stars, the habitation zone is so close to the star that the star's dazzling light can make it difficult for us to observe. For relatively close stars, the region appears farther away and easier to observe. This makes direct images of Alpha A Centauri a tempting target, to actually get images of these stars and find an exoplanet in them.
In general, the best way to use infrared light in places where the star is weak and the planet is strong, which can improve its contrast. For some exoplanets, this method also works well. However, the use of infrared light favors planets that are far away from their stars (those whose background light comes from stars but are very faint), huge planets (which make them brighter), and young planets (which are still hot at millions of years old, so they emit more infrared light).
Looking for terrestrial planets in habitable areas with direct imagery is not optimistic because terrestrial planets are colder, smaller, and closer to their stars. But new cameras and technology may be able to see these planets instead of "bubbling hot cauldrons."
Alpha Centauri's New Earth (NEAR) is an experience of finding planets in the Alpha Centauri galaxy using this new method. It utilizes an 8.2-meter super telescope located in Chile and a camera called VISIR: a VLT imager and spectrometer for mid-infrared.
Many infrared cameras can capture tiny wavelengths, about 5 microns (the wavelength of red light visible to the naked eye is 0.8 microns). VISIR is visible at 10 microns, a wavelength that emanates from some of the colder planets, and capturing images of this wavelength formation may reveal some planets that are more similar to Earth.
For a total of 19 days in May and June 2019, infrared cameras were used by astronomers to observe the Alpha Centauri galaxy. After 70 hours of effective observation, they used a number of instruments to suppress the light between the two stars, including placing them into a metal sundial observer that later blocked the light of the stars inside to reduce the flicker of the stars, from which to reduce the image of one star to reduce most of the light, or more. Some of the methods are quite sophisticated, with the two brightest stars in the sky being observed by one of the largest telescopes on Earth, and these methods can be used to reduce the brightness of these two stars.
They found that many of the artifacts — finding light or reflecting light into telescopes based on tracking instruments — had a hard time figuring out which lights were real and which were fake. They also found a large patch of light at the relatively clean image location that the unknown probe should have been, and to its right was a planet. Most of the images can be seen, which increases the confidence that researchers believe these lights exist. Previous observations took many years to rule out that these images were background stars or the Milky Way. What was most interesting to me was when I observed after 19 days that all the images were combined into an elongated spot that coincided with the trajectory of a planet orbiting Alpha A Centauri.
I want to stress again that they can't be sure that they are a planet, or even real. I would like to point out that a few years ago we were thrilled to discover that there might be a planet here orbiting Alpha A Centauri shortly after rejecting this conclusion when we had a brief flurry.
But if it were a planet, given its brightness, it would fit a planet 3 to 11 times its diameter on Earth, moving around the star at 16.5 billion miles, 11 times the distance between Earth and the Sun. Right in the stellar habitable zone. Previous observations have suggested that planets larger than 7 times the width of Earth do not exist, so it is likely that it is a planet the size of Neptune.
They point out that perhaps it is not a planet, but a cloud of dust. Just as the sun also has a cloud of dust moving around the shed from the comet. It's tiny, but in the mid-infrared it can get brighter. They calculated that Alpha A Centauri needed 60 times the amount of dust to orbit the Sun to explain the spots. That's a lot, but other similar stars have observed a lot of dust. So it's not impossible.
So is this planet orbiting Alpha A Centauri? Maybe. It seems to me that the author is right about that matter and has not made a huge statement or drawn any conclusions. It seems that their findings are correct, and this may be a planet.
Obviously, more observations are needed. If it were a planet, I'd love to see some pictures at some point, and depending on the motion of its trajectory, from Earth, it could be on the other side of the star. If they find something they haven't seen before, I'll be more confident that it exists.
But as the conceptual argument goes, this new camera and the methods they applied are quite encouraging. We know that planets can exist around stars like Alpha A Centauri — our Sun proves this, and we've also found many planets orbiting stars in geminis — so there's no reason to think that stars don't have planets around them.
What we need is more convincing evidence! But it's a fantastic start and I hope to come up with more observations soon. Growing up watching science fiction, aliens coming from Alpha Centauri were so common that the claim became almost a cliché. Of all the stars in the sky, I'm most excited about the planets I've found there.
BY: Phil Plait
FY: Mu Xun and Tang Xiaojiu
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