Astronomers have confirmed two remarkable planets orbiting the Sun-like star HD 137496: a scorching "hot super-Mercury" and a distant "cold Jupiter." Details are published on arXiv.org.
The Kepler Space Telescope, retired in October 2018 after discovering thousands of exoplanets, continues to yield surprises. Just months ago, AI analysis revealed over 350 new worlds in its data. Now, a team led by Tomás Silva from the University of Porto, Portugal, has identified two more using Kepler's transit signals, validated by radial velocity measurements from the HARPS and CORALIE spectrographs. These complementary techniques—transit photometry and radial velocity—account for most exoplanet detections to date.
HD 137496 is a Sun-like star with 1.03 solar masses and a radius of 1.59 solar radii. In contrast to our Sun, which formed about 4.6 billion years ago, this star is estimated at 8.3 billion years old.
The inner planet, HD 137496 b, is 30% larger and four times more massive than Earth, dominated by an iron core comprising over 70% of its mass. It orbits every 1.62 days at just 0.027 AU, with an equilibrium temperature of around 2130 K—earning it the classification of a "hot super-Mercury."
The outer planet, HD 137496 c, is a "cold Jupiter" with 7.66 Jupiter masses and an equilibrium temperature of about 370 K. It follows a highly eccentric orbit, completing one revolution in 480 days at 1.21 AU.
This system's uniqueness stands out: HD 137496 b is among the best-characterized dense planets, while HD 137496 c's high eccentricity offers prime opportunities to test planetary formation theories.
