Astronomers Discover Two Earth-Sized Exoplanets Orbiting Star HD 101581
Astronomers Discover Two Earth-Sized Exoplanets Orbiting Star HD 101581
An international team of astronomers has announced the discovery of two exoplanets orbiting the nearby star HD 101581. These newly discovered worlds are slightly smaller than Earth and orbit their host star at very close distances. The findings were published on December 12 on the pre-print server arXiv.
NASA's Transiting Exoplanet Survey Satellite (TESS) has identified over 7,300 candidate exoplanets, with 589 confirmed so far. Launched in April 2018, TESS has been surveying about 200,000 of the brightest stars near the Sun to search for transiting exoplanets.
In a recent study led by Michelle Kunimoto from the Massachusetts Institute of Technology (MIT), the team confirmed the planetary nature of two TESS Objects of Interest (TOIs). The researchers determined that transit signals detected in the light curve of HD 101581, or TOI-6276, were due to two Earth-sized exoplanets.
The first planet, HD 101581 b, is located closest to the star, with a radius of approximately 0.956 Earth radii and a mass not exceeding 3.6 Earth masses. It orbits its star every 4.47 days at a distance of about 0.046 AU. Its equilibrium temperature was estimated to be 834 K.
The second planet, HD 101581 c, is nearly the size of Earth, with a radius of 0.99 Earth radii and a maximum mass of 4.2 Earth masses. It has an orbital period of 6.21 days and is located about 0.057 AU from the star. Its equilibrium temperature was calculated to be 747 K.
Additionally, the team detected a possible signal from a third planet transiting HD 101581. If confirmed, this planet would have a radius of 0.98 Earth radii, a maximum mass of 3.6 Earth masses, and an orbital period of 7.87 days.
The host star, HD 101581, is a K dwarf located 41.7 light years away, with a radius of 0.63 solar radii and a mass of 0.74 solar masses. The star is estimated to be nearly 7 billion years old, with an effective temperature of 4,634 K and a metallicity of -0.5 dex.
In conclusion, the paper's authors note that HD 101581 is the brightest known star hosting multiple transiting planets with radii smaller than 1.5 Earth radii.
