A. Castro-González, V. Bourrier, J. Lillo-Box, J. -B. Delisle, D. J. Armstrong, D. Barrado, A. C. M. Correia
{"title":"Mapping the exo-Neptunian landscape. A ridge between the desert and savanna","authors":"A. Castro-González, V. Bourrier, J. Lillo-Box, J. -B. Delisle, D. J. Armstrong, D. Barrado, A. C. M. Correia","doi":"arxiv-2409.10517","DOIUrl":null,"url":null,"abstract":"Atmospheric and dynamical processes are thought to play a major role in\nshaping the distribution of close-in exoplanets. A striking feature of such\ndistribution is the Neptunian desert, a dearth of Neptunes on the\nshortest-period orbits. We aimed to define the boundaries of the Neptunian\ndesert and study its transition into the savanna, a moderately populated region\nat larger orbital distances. We built a sample of planets and candidates based\non the Kepler DR25 catalogue and weighed it according to the transit and\ndetection probabilities. We delimited the Neptunian desert as the close-in\nregion of the period-radius space with no planets at a 3$\\sigma$ level, and\nprovide the community with simple, ready-to-use approximate boundaries. We\nidentified an overdensity of planets separating the Neptunian desert from the\nsavanna (3.2 days $ \\lessapprox P_{\\rm orb}$ $\\lessapprox$ 5.7 days) that\nstands out at a 4.7$\\sigma$ level above the desert and at a 3.5$\\sigma$ level\nabove the savanna, which we propose to call the Neptunian ridge. The period\nrange of the ridge matches that of the hot Jupiter pileup ($\\simeq$3-5 days),\nwhich suggests that similar evolutionary processes might act on both\npopulations. We find that the occurrence fraction between the pileup and warm\nJupiters is about twice that between the Neptunian ridge and savanna. Our\nrevised landscape supports a previous hypothesis that a fraction of Neptunes\nwere brought to the edge of the desert (i.e. the newly identified ridge)\nthrough high-eccentricity tidal migration (HEM) late in their life, surviving\nthe evaporation that eroded Neptunes having arrived earlier in the desert. The\nridge thus appears as a true physical feature illustrating the interplay\nbetween photoevaporation and HEM, providing further evidence of their role in\nshaping the distribution of close-in Neptunes.","PeriodicalId":501209,"journal":{"name":"arXiv - PHYS - Earth and Planetary Astrophysics","volume":"34 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"arXiv - PHYS - Earth and Planetary Astrophysics","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/arxiv-2409.10517","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
Atmospheric and dynamical processes are thought to play a major role in
shaping the distribution of close-in exoplanets. A striking feature of such
distribution is the Neptunian desert, a dearth of Neptunes on the
shortest-period orbits. We aimed to define the boundaries of the Neptunian
desert and study its transition into the savanna, a moderately populated region
at larger orbital distances. We built a sample of planets and candidates based
on the Kepler DR25 catalogue and weighed it according to the transit and
detection probabilities. We delimited the Neptunian desert as the close-in
region of the period-radius space with no planets at a 3$\sigma$ level, and
provide the community with simple, ready-to-use approximate boundaries. We
identified an overdensity of planets separating the Neptunian desert from the
savanna (3.2 days $ \lessapprox P_{\rm orb}$ $\lessapprox$ 5.7 days) that
stands out at a 4.7$\sigma$ level above the desert and at a 3.5$\sigma$ level
above the savanna, which we propose to call the Neptunian ridge. The period
range of the ridge matches that of the hot Jupiter pileup ($\simeq$3-5 days),
which suggests that similar evolutionary processes might act on both
populations. We find that the occurrence fraction between the pileup and warm
Jupiters is about twice that between the Neptunian ridge and savanna. Our
revised landscape supports a previous hypothesis that a fraction of Neptunes
were brought to the edge of the desert (i.e. the newly identified ridge)
through high-eccentricity tidal migration (HEM) late in their life, surviving
the evaporation that eroded Neptunes having arrived earlier in the desert. The
ridge thus appears as a true physical feature illustrating the interplay
between photoevaporation and HEM, providing further evidence of their role in
shaping the distribution of close-in Neptunes.