2020ApJ...890...93G


Query : 2020ApJ...890...93G

2020ApJ...890...93G - Astrophys. J., 890, 93-93 (2020/February-3)

Deflating super-puffs: impact of photochemical hazes on the observed mass-radius relationship of low-mass planets.

GAO P. and ZHANG X.

Abstract (from CDS):

The observed mass-radius relationship of low-mass planets informs our understanding of their composition and evolution. Recent discoveries of low-mass, large-radius objects ("super-puffs") have challenged theories of planet formation and atmospheric loss, as their high inferred gas masses make them vulnerable to runaway accretion and hydrodynamic escape. Here we propose that high-altitude photochemical hazes could enhance the observed radii of low-mass planets and explain the nature of super-puffs. We construct model atmospheres in radiative-convective equilibrium and compute rates of atmospheric escape and haze distributions, taking into account haze coagulation, sedimentation, diffusion, and advection by an outflow wind. We develop mass-radius diagrams that include atmospheric lifetimes and haze opacity, which is enhanced by the outflow, such that young (∼0.1-1 Gyr), warm (Teq >= 500 K), low-mass objects (Mc < 4 M) should experience the most apparent radius enhancement due to hazes, reaching factors of three. This reconciles the densities and ages of the most extreme super-puffs. For Kepler-51b, the inclusion of hazes reduces its inferred gas mass fraction to <10%, similar to that of planets on the large-radius side of the sub-Neptune radius gap. This suggests that Kepler-51b may be evolving toward that population and that some warm sub-Neptunes may have evolved from super-puffs. Hazes also render transmission spectra of super-puffs and sub-Neptunes featureless, consistent with recent measurements. Our hypothesis can be tested by future observations of super-puffs' transmission spectra at mid-infrared wavelengths, where we predict that the planet radius will be half of that observed in the near-infrared.

Abstract Copyright: © 2020. The American Astronomical Society. All rights reserved.

Journal keyword(s): Exoplanet atmospheres - Exoplanet structure - Exoplanet atmospheric composition - Exoplanet evolution - Exoplanet astronomy - Exoplanets

Simbad objects: 21

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Number of rows : 21
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 NAME V1298 Tau d Pl 04 05 19.5912137335 +20 09 25.563534185           ~ 12 0
2 NAME V1298 Tau e Pl 04 05 19.5912137335 +20 09 25.563534185           ~ 7 0
3 NAME V1298 Tau c Pl 04 05 19.5912137335 +20 09 25.563534185           ~ 16 0
4 EPIC 210818897 b Pl 04 05 19.5912137335 +20 09 25.563534185           ~ 22 0
5 * 51 Eri b Pl 04 37 36.1323118067 -02 28 24.778826936           ~ 144 0
6 CoRoT-24b Pl 06 47 41.4116571586 -03 43 09.483794512           ~ 19 0
7 K2-33b Pl 16 10 14.7378782154 -19 19 09.407200797           ~ 51 0
8 NAME G 139-21b Pl 17 15 18.9337265994 +04 57 50.064695682           ~ 636 1
9 G 139-21 PM* 17 15 18.9339850845 +04 57 50.066612336       14.394   M4.5V 286 1
10 Kepler-177c Pl 19 04 11.3086186360 +45 03 11.548856286           ~ 34 0
11 Kepler-47c Pl 19 41 11.4984891255 +46 55 13.705101341           ~ 59 1
12 Kepler-51 Ro* 19 45 55.1428629456 +49 56 15.650520684           ~ 109 1
13 Kepler-51b Pl 19 45 55.1429734720 +49 56 15.650638630           ~ 79 1
14 Kepler-51d Pl 19 45 55.1429734720 +49 56 15.650638630           ~ 60 0
15 Kepler-51c Pl 19 45 55.1429734720 +49 56 15.650638630           ~ 43 1
16 Kepler-11e Pl 19 48 27.6228219845 +41 54 32.902654079           ~ 115 1
17 Kepler-87c Pl 19 51 40.0490992347 +46 57 54.427022288           ~ 43 1
18 Kepler-223e Pl 19 53 16.4203115605 +47 16 46.308061008           ~ 30 0
19 Kepler-223d Pl 19 53 16.4203115605 +47 16 46.308061008           ~ 35 0
20 Kepler-79d Pl 20 02 04.1057596467 +44 22 53.646600034           ~ 73 1
21 HD 222259Ab Pl 23 39 39.4809609959 -69 11 44.709342501           ~ 36 0

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2022.09.28-01:17:49

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