Astronomers using a new technique may not only have found a super-Earth near a neighboring star, but they may have imaged it directly. And it could be fun and cozy in the habitable zone around Alpha Centauri.
It’s much easier to see giant planets than planets the size of the Earth. Whatever detection method is used, larger planets are simply a larger needle in the cosmic haystack. But in general, astronomers are very interested in planets that resemble Earth. And finding them is much more difficult.
We thought we would have to wait for the ultra-powerful telescopes currently under construction before we could directly image exoplanets.
Facilities such as the Giant Magellan Telescope and the European Extremely Large Telescope will bring tremendous powers of observation to the exoplanet imaging task.
But a team of researchers has developed a new technique that could get the job done. They say they have pictured a possible sub-Neptune / super-Earth planet orbiting one of our closest neighbors, Alpha Centauri A.
The team presented their observations in an article in Nature Communications entitled “Imaging low-mass planets within the habitable zone of α Centauri.” The lead author is Kevin Wagner, an astronomer and Sagan Fellow at the University of Arizona.
Although astronomers have found low-mass exoplanets before, they have never seen their light. They watched the planets reveal themselves by pulling on their stars. And they have watched the light from the stars that host these planets descend as the planet passes in front of the star.
But they never made a direct image of it. Maybe so far.
This new detection method comes down to infrared. One of the challenges in imaging Earth-sized exoplanets in infrared is to distinguish the light that comes from an exoplanet when that light is washed away by all of the star’s infrared background radiation.
Astronomers can search for exoplanets in wavelengths where the infrared in the background is reduced, but at those same wavelengths, moderate Earth-like planets are faint.
One method is to look in the near infrared (NIR) part of the spectrum. In NIR, the planet’s thermal glow is not so washed away by the star. But the starlight is still dazzling, and millions of times brighter than the planet. So just looking at the NIR is not a total solution.
The solution may be the NEAR (New Earths in the AlphaCen Region) instrument used in this study. NEAR is mounted on ESO’s European Southern Observatory’s Very Large Telescope (VLT) in Chile. It works with the VISIR instrument, also on the VLT. The group behind NEAR is the Breakthrough Watch, part of Yuri Milner’s Breakthrough Initiatives.
The NEAR instrument not only observes in the desired part of the infrared spectrum, but also uses a coronagraph.
The Breakthrough group thought that the NEAR instrument used on an 8-meter ground telescope would allow better observations of the Alpha Centauri System and its planets.
So they built the instrument in collaboration with ESO and installed it on the Very Large Telescope.
This new finding was the result of 100 hours of cumulative observations with NEAR and the VLT.
“These results,” the authors write, “demonstrate the feasibility of imaging exoplanets in rocky habitable zones with current and future telescopes.”
The 100-hour commissioning run was intended to demonstrate the power of the instrument.
The team says that based on about 80 percent of the best images in that series, the NEAR instrument is an order of magnitude better than other methods of observing “… warm sub-Neptune-sized planets in a large space. part of the habitable zone of α Centauri A. “
They may also have found a planet. “We are also discussing a possible detection of an exoplanet or exozodiac disc around Centauri A,” they write. However, an instrumental artifact of unknown origin cannot be ruled out.
This isn’t the first time astronomers have found exoplanets in the Alpha Centauri system.
There are a few confirmed planets in the system, and there are other candidates as well.
But none of them have been directly imaged like this new potential planet, which has the placeholder C1, and the first potential detection is around the M dwarf in the system, Proxima Centauri.
Follow-up observations will have to confirm or cancel the discovery.
It’s exciting to think that a warm Neptune-class exoplanet could orbit a sun-like star in our nearest neighboring galaxy. One of the goals of the breakthrough initiatives is to send light sail spacecraft to the Alpha Centauri system and give us a look.
But that prospect is out of reach for the time being. And in some ways, this discovery is not so much about the planet as it is about the technology developed to detect it.
The vast majority of the discovered exoplanets are gigantic planets comparable in mass to Jupiter, Saturn and Neptune. They are the easiest to find. But as people of the Earth, we are mainly interested in planets like ours.
Earth-like planets in a star’s habitable zone excite us about the prospects for life on another planet. But they can also tell us a lot about our own solar system, and how solar systems in general form and evolve.
If C1 turns out to be a planet, then the Breakthrough Group has succeeded in a vital undertaking. They are the first to detect an Earth-like planet through direct imaging.
Not only that, but they also did it with an 8-meter ground telescope and an instrument specifically designed and developed to detect these types of planets in the Alpha Centauri system.
The authors are confident that NEAR can perform well even when compared to much larger telescopes. The article’s conclusion describes the overall sensitivity of the instrument. Then they write, “This would in principle be enough to detect an Earth analog planet around α Centauri A (~ 20 µJy) in just a few hours, which is in line with the expectations for the ELTs.”
The E-ELT will have a 39 meter primary mirror. One of its possibilities and design goals is to directly image exoplanets, especially smaller ones on Earth.
Of course, the E-ELT will be a tremendously powerful telescope that will undoubtedly fuel scientific discoveries for a long time, not only in the creation of exoplanets, but in a host of other ways.
And other giant ground-based telescopes will also change the game of making exoplanets.
What took NEAR hours to see, it could take only minutes to see the E-ELT, the Thirty Meter Telescope or the Giant Magellan Telescope.
NEAR cannot compete with those telescopes and it was never intended to.
But if these results are confirmed, NEAR has succeeded where no one else has, and at a fraction of the price of a new telescope.
Regardless, what NEAR has accomplished likely represents the future of exoplanet research. Rather than wide-ranging studies like Kepler and TESS, scientists will soon be able to focus on individual planets.
This article was originally published by Universe Today. Read the original article.