TESS Finds its Third Planet, a sub-Neptune with a 36-Day Orbit

After solely three months of operation, NASA’s TESS (Transiting Exoplanet Survey Satellite tv for pc) spacecraft is delivering on its mission to search out extra exoplanets. A brand new paper presents the newest discovering: a sub-Neptune planet with a 36-day orbit round its star. That is the third confirmed exoplanet that TESS has discovered.

The planet orbits a Ok-dwarf star about 52 mild years away, within the constellation Reticulum. In astronomical phrases, this makes the planet fairly near us, and an incredible candidate for follow-up observations. Even higher, it could have a sibling planet about the identical measurement as Earth.

The planet itself is named HD 21749b, and it’s about 3 times the scale of Earth, and about 23 occasions the mass of Earth. This makes it a sub-Neptune, a planet someplace between Earth and Neptune in measurement and mass. It’s star is a Ok-type star, or Ok-dwarf star, named HD 21749. The star is about 80% the mass of the Solar.

“This planet has a better density than Neptune, but it surely isn’t rocky.” – Diana Dragomir, MIT Kavli Institute for Astrophysics and House Analysis.

“This planet has a better density than Neptune, but it surely isn’t rocky. It may very well be a water planet or have another sort of considerable ambiance,” defined Diana Dragomir, a Hubble Fellow at MKI and lead creator of the paper describing the discover.

With a 36 day orbit, the brand new planet is near its star, and its floor temperatures are anticipated to be round 150 levels Celsius (300 levels Fahrenheit). HD 21749b is the longest-period transiting planet inside 100 light-years of the photo voltaic system. It additionally has the good floor temperature of a transiting exoplanet round a star brighter than 10th magnitude.

The brand new exoplanet HD 21749b, and its star, HD 21749. The system might have one other planet that’s in regards to the measurement of Earth. Picture Credit score: By NASA/MIT/TESS – https://static01.nyt.com/pictures/2019/01/08/local weather/08TESS2/merlin_148878360_2fd4c6fe-ad22-400b-a882-f6b3a698a573-superJumbo.jpg, Public Area, https://commons.wikimedia.org/w/index.php?curid=75686540

The brand new planet is among the three densest exoplanets with a mass above 15 Earth plenty. The opposite two have been discovered by Kepler, and are referred to as Kepler 131b and K2 66b. These two have densities that counsel rocky compositions, however they’re much less huge than the brand new planet. However the density of the brand new planet, HD 21749b, counsel it has a considerable ambiance.

Scientists will likely be wanting to do follow-up research on the brand new planet, particularly of its ambiance. The James Webb House Telescope (JWST) can be used for that, as soon as it’s in enterprise. However in line with the authors of the paper, “HD 21749b isn’t a great goal for atmospheric characterization with the JWST,” due to the time it takes. However given the shortage of any such exoplanet, the required observing time with the JWST could also be warranted.

The invention of extra planets is all the time thrilling. However on this case, the star it’s orbiting provides to the joy. Ok-type stars like HD 21749 are very secure and long-lived stars. Their small plenty give the celebrities extraordinarily lengthy life spans. They’ll keep on the main-sequence for between 15-70 billion years, giving life a very long time to begin and evolve, if situations are proper on any of the star’s planets. Our personal Solar will solely be secure for about 10 billion years, and half that point has already handed.

Alpha Centauri B, the brilliant star on the precise, is a Ok-type star just like HD 21749. Picture Credit score: By Skatebiker at English Wikipedia, CC BY-SA three.zero, https://commons.wikimedia.org/w/index.php?curid=46833562

Ok-type stars additionally emit much less ultraviolet radiation than stars like our Solar. UV can harm DNA and hamper the event of life. They’re additionally extra plentiful than stars like our Solar, so that they’re key to the seek for life.

The system has one other planet candidate, too. This one is Earth-sized, and if confirmed by follow-up observations, it could be the smallest planet discovered by TESS to date. The planet, referred to as TOI 186.02 for now, is about 2.5 occasions the mass of Earth. Not a lot else is thought about it but.

TESS is on a two-year mission to search out exoplanets. It’s the successor to the profitable Kepler mission. It should survey over 85% of the sky, and can take a look at 200,000 dwarf-type stars to seek for exoplanets. When TESS finds a candidate exoplanet, follow-up observations by different telescopes will verify its findings.

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