Astronomers have discovered three new ‘Super Earths’ orbiting a nearby star that is just 54 light years away. Each of the three planets have a mass 7-8 times that of Earth. Lauren Weiss of University of California, Berkeley and co-author of the study said that all three Super Earths orbit their host star at a distance closer than Mercury orbits our Sun.
Doppler method helped detect these planets
Researchers said that the newly discovered planets take just five, 15 and 24 days to complete their orbits. A Super Earth is an exoplanet with a mass higher than that of Earth, but well below the mass of our solar systems’ smaller ice giants like Neptune and Uranus. Findings of the study were published in the Astrophysical Journal.
The planets are invisible to the naked eye, but researchers were able to discover them using the Doppler method. They detected ‘wobbles’ of the host star HD 7924 as planets orbited and pulled on the star gravitationally. The Automated Planet Finder (APF) Telescope at Lick Observatory and Keck Observatory on Maunakea, Hawaii traced out each of the planets’ orbits over several years.
The Automatic Photometric Telescope (APT) at Fairborn Observatory further measured the brightness of HD 7924 to re-confirm the validity of planet discoveries. Researchers were initially using APF like a regular telescope, but later they wrote software to let a robot handle it. The Keck Observatory had first observed the planets orbiting HD 7924 in 2009.
It took over six years to find these Super Earths
Keck had discovered the innermost Super Earth in 2009 using the HIRES instrument on the Keck I telescope. But it took another six years for APF Telescope and Keck Observatory to find the two other planets orbiting HD 7924. Astronomers expect to find more such planetary systems around nearby stars in coming years.
It is a significant discovery because most of the exoplanets discovered so far have been the size of Neptune, about 17 times the mass of Earth, or even larger. APF has proven that it is capable of finding small planets around nearby stars, some of which may harbor conditions suitable for life.
