Two Earth-Sized Exoplanets Detected

Date: 23 December 2024 - 21:40

News ID: ۱۳۵۰۲۵

WASHINGTON (Phys.org) -- An international team of astronomers has reported the discovery of two exoplanets orbiting a nearby star known as HD 101581. The newfound alien worlds are slightly smaller than Earth and orbit its host very closely. The discovery was detailed in a paper published Dec. 12 on the pre-print server arXiv.
NASA’s Transiting Exoplanet Survey Satellite (TESS) has identified more than 7,300 candidate exoplanets (TESS Objects of Interest, or TOI), of which 589 have been confirmed so far. Since its launch in April 2018, the satellite has been conducting a survey of about 200,000 of the brightest stars near the sun with the aim of searching for transiting exoplanets.
A recent study published by a group of astronomers led by Michelle Kunimoto of the Massachusetts Institute of Technology (MIT) has confirmed the planetary nature of two TOIs. The team reports that transit signals identified by TESS in the light curve of TOI-6276, or HD 101581, are caused by two Earth-sized extrasolar worlds.
“Both planets were discovered in sectors 63 and 64 TESS observations and statistically validated with supporting ground-based follow-up,” the researchers wrote.
The planet closer to the star, designated HD 101581 b, has a radius of approximately 0.956 Earth radii and its mass was calculated to be not larger than 3.6 Earth masses. The planet orbits its host every 4.47 days, at a distance of about 0.046 AU from it. The equilibrium temperature of HD 101581 b was estimated to be 834 K.
The second planet, which received the designation HD 101581 c, is almost the size of the Earth (0.99 Earth radii), while its maximum mass was determined to be 4.2 Earth masses. HD 101581 c has an orbital period of 6.21 days, is separated from the parent star by approximately 0.057 AU, and its equilibrium temperature was calculated to be at a level of 747 K.
The astronomers add that they also identified a signal that probably originated from a third planet transiting HD 101581. If confirmed, this outermost planet would have a radius of about 0.98 Earth radii, a maximum mass of 3.6 Earth masses, and an orbital period of approximately 7.87 days.
When it comes to the host star, HD 101581, it is a K dwarf with a radius of about 0.63 solar radii and a mass of around 0.74 solar masses. The star, which is located some 41.7 light years away, is estimated to be nearly 7 billion years old, has an effective temperature of 4,634 K, and metallicity at a level of -0.5 dex.
In concluding remarks, the authors of the paper note that HD 101581, with a V-band magnitude of 7.77 mag, is therefore the brightest known star hosting multiple transiting planets with radii below 1.5 Earth radii.