James Webb Space Telescope studies mysterious exoplanet with a possible watery past

"Kempton added that if GJ 1214 b indeed proves to possess a water-rich atmosphere, the exoplanet may have been a "water world" in its distant past, an exoplanet replete with large amounts of watery and icy material at the time of its formation."

Ref - A reflective, metal-rich atmosphere for GJ 1214b from its JWST phase curve, https://www.nature.com/articles/s41586-023-06159-5, 10-May-2023.

"Abstract There are no planets intermediate in size between Earth and Neptune in our Solar System, yet these objects are found around a substantial fraction of other stars [1]. Population statistics show that close-in planets in this size range bifurcate into two classes based on their radii [2, 3]. It is hypothesized that the group with larger radii (referred to as “sub-Neptunes”) is distinguished by having hydrogen-dominated atmospheres that are a few percent of the total mass of the planets [4]. GJ 1214b is an archetype sub-Neptune that has been observed extensively using transmission spectroscopy to test this hypothesis [5-14]. However, the measured spectra are featureless, and thus inconclusive, due to the presence of high-altitude aerosols in the planet’s atmosphere. Here we report a spectroscopic thermal phase curve of GJ 1214b obtained with JWST in the mid-infrared. The dayside and nightside spectra (average brightness temperatures of 553 ± 9 and 437 ± 19 K, respectively) each show >3σ evidence of absorption features, with H2O as the most likely cause in both..."

My note. 553 K and 437 K is a nice warm place to visit and enjoy the beaches :) Properties reported here; http://exoplanet.eu/catalog/gj_1214_b/

The age reported is 6 Gyr, I calculate P = 1.5806E+00 day, reported value P = 1.5804 day. In 1 Gyr 2.3109E+11 revolutions completed or more than 231 billion. This assumes a stable orbit around the M dwarf host star. Nearly 1.39E+12 revolutions if stable using host star age of 6 Gyr. No doubt, this exoplanet has a very interesting past.