Satellite Survey Satellite Transit of & # 39; the NASA exoplanet, TESS, discovered a third small planet outside our solar system, scientists announced this week at the annual meeting of the American Society Astronomical f & # 39; Seattle.
The new planet, HD 21749b by name, orbit & # 39; strong dwarf star about 53 light years and close & # 39; away, in the constellation reticulum, and appears to be the longest orbital period of three planets s & # 39; now identified by TESS. HD 21749b travels around its star in 36 relatively comfortable day, compared with the two other planets – Mensae Pi b, "super-Earth" b'orbita 6.3 days, and LHS 3844b, world rock which speeds around the star 11 hours only. All three planets have been discovered in the first three months of TESS observations.
The surface of the new planet x & # 39; probably about 300 degrees Fahrenheit – relatively cool, because of its proximity to its star, which is almost the same size as the sun.
"It is the biggest small planet we know of & # 39; around this star power," says Diana Dragomir, postdoc at the Institute & # 39; the Astaviżika and Space Research & # 39; MIT, who led the new discovery. "We know a lot about atmospheres of & # 39; hot planets, but because it is very difficult to find small planets revolving around their stars, and therefore colder, have failed to learn much about these smaller planets and colder . But here we were lucky, and instructed it, and now we nistudjawha f & # 39; more detail. "
The planet is about three times the size of Earth, which tqiegħduha in the category of & # 39; "sub-Neptune." B & # 39; surprising way, is also 23 times as much mass as the Earth. But it is unlikely that the planet is rocky and therefore habitable; it is more likely made of gas, of a kind that is much more dense atmospheres of Neptune or Uranus.
"We think that this planet is not so gaseous like Neptune or Uranus, which are mostly hydrogen and are really swelling," says Dragomir. "The planet x & # 39; likely to density & # 39; water, or thick atmosphere."
Serendipitously, the researchers also found evidence of a second planet, although not yet confirmed, in the same planetary system, shorter b'orbit 7.8 days. If confirmed as a planet, you & # 39; is the first planet & # 39; world as discovered by TESS.
Besides lodged – their results – meeting & # 39; to – AAS, to – researchers sent a document to Astrophysical Journal Letters.
Since its launch in & # 39; April 2018, TESS, a mission led by MIT, has been monitoring air, sector b & # 39; sector, for rjuski momentary view of & # 39; 200,000 stars nearby. Such dips x & # 39; likely represent a planet passing in front of that star.
The train four satellite & # 39; his cameras on board each sector to 27 days, taking the light from the stars in & # 39; that particular segment before changing to see what's next. During the mission & # 39; two, the TESS will look almost the entire sky by monitoring and pools of overlapping pieces of heaven & # 39; night. The satellite will spend the first year to survey the sky in the Southern Hemisphere, before turning around to take in the sky & # 39; of the Hemisphere & # 39; On.
The mission issued to the public all the data gathered TESS & # 39; now the first three of the 13 sectors that will monitor the southern sky. For their new analysis, the researchers examined this data, collected between July and 14 October.
Within the data sector 1, Dragomir identified one transit, or running, in the light of the star HD 21749. As the satellite collects data only from one sector to 27 days, it is difficult to identify planets with & # 39; Orbit longer than the period & # 39; time; by the time a planet passes again, the satellite may have changed to see another slice of heaven.
To complicate things, the star itself is relatively active, and Dragomir was not sure if she found was a single transit result & # 39; planet passing or cutting in & # 39; stellar activity. So she found a second set of data, collected by the Radial Speed & # 39; High Accuracy Planet Searcher, or HARP, spettrografija of & # 39; high precision installed on a large telescope based on the ground in Chile, to identify exoplanets with their gravitattiv tug on their host stars.
"They looked at this system & # 39; star ten years ago and never announced anything because they were not sure whether they were looking at planet against the activity & # 39; the star," says Dragomir. "But we had this one transit, and we knew something was there."
When the researchers examined the data Harp, discovered repeated signal coming from the HD 21 749 every 36 days. From this, they calculated that, if in fact they were seen in transit TESS data from the sector 1, then another transit must appear 36 days later, on the date of the sector 3. When such data made available to the public , created a momentary glitch data gaps just in time Dragomir wait to place second transit.
"Because there was an interruption in data around that time, we initially we have not seen the second transit, and were quite disappointed," recalls Dragomir. "But we estrajna data and żomajna to look more carefully, and found what looks like the end of & # 39; transit."
She and her colleagues compared the model with the first full transit originally discovered, and found almost perfect match – an indication that the planet passed again in front of its star, f & # 39; orbit of & # 39; 36 days.
"There was some work & # 39; detective involved, and the good people were there at the right time" said Dragomir. "But we were lucky and caught the signs, and they were really clear."
They also used data from Planet Finder spectrograph, an instrument installed on the Magellan telescope in Chile, to further validate their findings and limit the mass and orbit of the planet.
Once TESS has completed its screening of & # 39; two years the entire sky, the science team is committed to providing information on 50 small planet less than four & # 39; times the size of Earth to the astronomical community for further follow-up, or b & # 39; telescopes based on land or James Webb Space Telescope future.
"We have three planets kkonfermajna s & # 39; now, and there is so much more that both are still waiting for the telescope and people to confirm the time," says Dragomir. "So going very well, and TESS are already helping us to learn about the diversity of & # 39; these small planets."
TESS is led NASA Astrophysics Explorer mission and operated by MIT in & # 39; C Cambridge, Massachusetts, and managed by Goddard. Additional partners include Northrop Grumman, based in Falls Church, Virginia; The Research Center of NASA Ames in Silicon Valley of California; citizens Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts; the MIT Lincoln Laboratory; and the Space Telescope Science Institute in South & # 39; Baltimore. More than a dozen universities, institutes & # 39; research, and observatories around the world are participating in the mission.