Properties for WASP-189 b is here,
https://exoplanet.eu/catalog/wasp_189_b--6871/
Space.com reported, "Beyond hot Jupiters, the mission, which was partly built by undergraduate and graduate students at the University of Colorado, Boulder, might also help astronomers better understand smaller worlds too. There's a lot of evidence that suggests that super-Earths begin as planets the size of Neptune with large, puffy atmospheres, which then lose so much mass that all that is left is the rocky core and possibly a thin atmosphere," said France."
My observation. Our solar system has no super-earth analog planets and thus planets that formed much larger, closer to the Sun, and lost most of their early atmospheres to space and end up a super-earth today. A six exoplanet system with all six exoplanets are super-earths was recently reported too, all inside where we see Venus today in our solar system, orbiting a star a bit more than 1 solar mass.
The TESS-Keck Survey XVII: Precise Mass Measurements in a Young, High Multiplicity Transiting Planet System using Radial Velocities and Transit Timing Variations,
https://arxiv.org/abs/2312.04635
My note, from the 33-page PDF report, "Here we present a follow-up analysis of TOI-1136, a system with at least six transiting planets first characterized by Dai et al. (2023, hereafter D23), and a candidate seventh. TOI-1136 is a young (700 ± 100 Myr), bright (V=9.5) G dwarf that has several planets that exhibit significant transit timing variations (TTVs), allowing for the precise characterization of most planet masses with photometry alone...TOI-1136 consists entirely of sub-Neptune sized planets, likely none of them terrestrial. Further, none are large enough to call gas giants, either, and the planet sizes do not follow any clear sequence or demarcation, with the largest planet third from the star. We highlight the architectural differences in Figure 9. TOI-1136’s youth is yet another distinguishing feature that adds to the system’s value.", ref -
https://arxiv.org/pdf/2312.04635.pdf.
Concerning WASP-189 b, the atmosphere mass loss seems high.
Ref - CUTE Reveals Escaping Metals in the Upper Atmosphere of the Ultrahot Jupiter WASP-189b,
https://iopscience.iop.org/article/10.3847/2041-8213/acef1c, 31-August-2023.
My note, the reference paper states. “The best-fit model implies a mass-loss rate of about 4 × 10^8 kg s^−1, which is more than 300 times higher than the mass-loss rate predicted by our reference model. This new mass-loss rate, however, is still consistent with stellar XUV energy-limited mass-loss rate (e.g., Erkaev et al. 2007) with a heating efficiency of about 10% in the upper atmosphere (assuming that escape is powered by stellar radiation at 0.1–100 nm, which is conservative in this case). The best-fit temperature profile is also significantly hotter than the reference model temperature profile in the upper atmosphere. This could be explained either by an additional source of direct heating or lower radiative cooling rates. The difference between the observed transit depths that coincide with the Fe ii lines and the best-fit model could arise from uncertainties in photoionization and recombination rates. A higher fraction of Fe ii over Fe iii could produce a larger transit depth that is still consistent with solar abundances.”
My note. Extrapolating the mass loss rate for 0.8E+9 years, ~ 1.009E+25 kg atmosphere loss. The Moon is about 7.3 x 10^22 kg. The Earth is about 5.97E+24 kg mass.
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