On January 2019, an Earth-sized planet was first observed by the National Aeronautics and Space Administration's (NASA) Transiting Exoplanet Survey Satellite (TESS). Just recently, the exoplanet's existence had been confirmed through ground-based follow-up observations.
The satellite was tasked to find the most promising exoplanets that are close to the brightest stars. TESS has made follow-up observations much easier for scientists. The researchers predicted that TESS would be able to find around 300 Earth-sized or Super-Earth-sized exoplanets within two years. The Kepler space telescope, the predecessor of TESS, found other exoplanets as well. However, most of them are larger than Earth.
Johanna Teske, from the Carnegie Science Institute and the second author of the paper, is excited that TESS has already become a game changer in the planet-hunting field even though it was just launched a year ago. Teske explains that they have collaborated with the TESS follow-up community for updates on the surveys done by the satellite or any interesting targets that were flagged.
The scientist cited that two of the newly discovered planets are orbiting an orange main sequence star, called HD 21749, at about 53 light years from the Earth. The orange star is about 70% of the mass of the sun.
According to the data that the scientists have analyzed, there were only two planets in that solar system. HD 21749c Is the Earth-sized planet, while the HD 21749b is a hot sub-Neptune planet.
As part of the consortium that operates the Las Campanas Observatory in Chile, the Carnegie Institute for Science plays an important role in this discovery. The Magellan Telescopes that are set up in the Las Campanas Observatory was the equipment used to confirm the existence of the two planets. There is a unique attachment installed on the Magellan II telescope called the Planet Finder Spectrograph (PFS) was developed by the scientists, especially for this study. Aside from confirming both planets, the PFS is also key to measuring the mass of HD21749b the hot sub-Neptune planet.
The PFS relies on the radial velocity method which was used to determine the mass of an exoplanet. The data on the planet's density and composition will soon follow since the mass is now known.
Measuring the exoplanet's mass means that the PFS has data on the said exoplanet's gravity. Naturally, the orange star exerts a strong influence on the two exoplanets orbiting itAs gravity works both ways, the exoplanets also impart a gravitational pull that causes a slight wobble to the star. This wobble is then detected by the PFS.
As a rule, larger wobbles occur when a massive planet is orbiting a star. While smaller wobbles occur for smaller planets.
