A new super-Earth and a Neptune sized exoplanet discovered
Astronomers discovered a rocky ‘super-Earth’ exoplanet orbiting one of the Milky Way’s oldest stars
About 280 light years away from Earth lies TOI-561…one of the oldest stars in the Milky Way galaxy. It is among the rare population of stars in our galaxy, located in a region known as the galactic thick disk.
These stars believe to have fewer heavy elements compared to other typical stars in our Milky Way galaxy.
The star hosts an exoplanet called TOI-561b. The exoplanet is about fifty percent larger and three percent more massive than our blue planet. It lies extremely close to its parent star and completes one orbit in less than twelve hours.
Given that proximity to its parent star, the exoplanet is unusually hot with average surface temperature of over 1,726 degrees Celsius. That’s too hot to host any life form as we know it.
Astronomers were surprised to found that exoplanet’s density is similar to that of Earth, as its density was expected to be higher. This supports the idea that planet is pretty old.
Massive stars produce heavy elements (such as iron and magnesium) by fusion reactions in their hearts. These elements are stocking up in our and other galaxies as more and more stars release such elements when they go supernova.
TOI-561b’s low density indicates that it contains relatively low amount of heavy elements and so the exoplanet is very old, forming probably ten billion or so years ago.
Thus making TOI-561b as one of the oldest rocky worlds yet discovered. The existence of this exoplanet indicates that Universe has been producing rocky planets almost since its birth fourteen billion years ago.
Scientists discovered and characterized the exoplanet by using data from NASA’s Transiting Exoplanet Survey Satellite (TESS) and the W.M. Keck Observatory in Hawaii. TOI-561 also hosts two other exoplanets in addition to TOI-561b.
But other two exoplanets are very big and are not dense enough to be a rocky world.
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Astronomers discovered Neptune-sized exoplanet
An international team of scientists has discovered a Neptune sized planet named NGTS-14Ab. The exoplanet is about thirty percent larger than Neptune. NGTS-14Ab was discovered as part of the Next Generation Transit Survey (NGTS).
NGTS is a wide field ground based robotic search focused mainly to look for Neptune sized and smaller extrasolar planets transiting bright stars. The facility is located in Chile and operates at red optical wavelengths.
It uses transit method to look for new exoplanets by precisely measuring the dimming of star light as exoplanet passes in front of it.
Exoplanet NGTS-14Ab revolves around NGTS-14A, a K-dwarf in this binary star system. The system is called NGTS-14 and it is located at some 1,000 light years away from us.
Photometric observations of NGTS-14 system have identified a transit signal in the light curve of NGTS-14A.
The planetary nature of this signal was confirmed by using NASA’s Transiting Exoplanet Survey Satellite (TESS) and various other ground operated telescopes, in the follow up observations.
The newly discovered Neptune sized exoplanet has a radius of about 0.44 Jupiter radii and a mass of about 0.1 Jupiter masses. The exoplanets equilibrium temperature was calculated to be around 870°C.
It orbits its host star in every 3.53 days at a distance of about 0.04 Astronomical Units (AU).
This short orbital period of exoplanet along with the fact that it is marginally bigger and more huge than Neptune, place NGTS-14Ab in Neptunian desert.
Star NGTS-14A of this binary star system (NGTS-14) is about 5.9 billion years old and has a radius of about 0.84 solar radii. It is ten percent less massive than our Sun. Star’s effective temperature is calculated to be 4913.85°C.
While the other star (named NGTS-14B) of the binary system is thought to be a star of M2.5V spectral type. It is separated by some 1,137 AU from NGTS-14A.
For more information: NGTS-14Ab: a Neptune-sized transiting planet in the desert