SIMBAD references

2021ApJ...921...24S - Astrophys. J., 921, 24-24 (2021/November-1)

The occurrence-weighted median planets discovered by transit surveys orbiting solar-type stars and their implications for planet formation and evolution.


Abstract (from CDS):

Since planet occurrence and primordial atmospheric retention probability increase with period, the occurrence-weighted median planets discovered by transit surveys may bear little resemblance to the low-occurrence, short-period planets sculpted by atmospheric escape ordinarily used to calibrate mass-radius relations and planet formation models. An occurrence-weighted mass-radius relation for the low-mass planets discovered so far by transit surveys orbiting solar-type stars requires both occurrence-weighted median Earth-mass and Neptune-mass planets to have a few percent of their masses in hydrogen/helium (H/He) atmospheres. Unlike the Earth that finished forming long after the protosolar nebula was dissipated, these occurrence-weighted median Earth-mass planets must have formed early in their systems' histories. The existence of significant H/He atmospheres around Earth-mass planets confirms an important prediction of the core-accretion model of planet formation. It also implies core masses Mc in the range 2 M <= Mc <= 8 M that can retain their primordial atmospheres. If atmospheric escape is driven by photoevaporation due to extreme-ultraviolet (EUV) flux, then our observation requires a reduction in the fraction of incident EUV flux converted into work usually assumed in photoevaporation models. If atmospheric escape is core driven, then the occurrence-weighted median Earth-mass planets must have large Bond albedos. In contrast to Uranus and Neptune that have at least 10% of their masses in H/He atmospheres, these occurrence-weighted median Neptune-mass planets are H/He poor. The implication is that they experienced collisions or formed in much shorter-lived and/or hotter parts of their parent protoplanetary disks than Uranus and Neptune's formation location in the protosolar nebula.

Abstract Copyright: © 2021. The American Astronomical Society. All rights reserved.

Journal keyword(s): Super Earths - Mini Neptunes - Exoplanets - Exoplanet formation - Exoplanet evolution - Exoplanet atmospheres

Status at CDS : Large table(s) will be appraised for possible ingestion in VizieR.

Simbad objects: 328

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