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SUMMARY:Can Super-Earths Be Born Rocky? Separating Survey Selection from F
 ormation in the Deficit of Large Rocky Planets at Low Insolation
DTSTART;VALUE=DATE-TIME:20261028T164500Z
DTEND;VALUE=DATE-TIME:20261028T165500Z
DTSTAMP;VALUE=DATE-TIME:20261024T120219Z
UID:indico-contribution-3669@nyx.physics.mcgill.ca
DESCRIPTION:Speakers: HongYi Mei (University of Toronto)\nSmall planets sh
 ow a radius valley near 1.8 R⊕ splitting them into rocky super-Earths an
 d volatile sub-Neptunes\, but whether rocky planets can be born rocky\, or
  are all stripped cores of planets that lost an envelope\, is still unsett
 led. We test two planet formation scenarios\, Sub-Neptune (no planet born 
 rocky) and Sub-Neptune+Super-Earth (some are)\, as priors to analyze this 
 question. We build the scenarios by building synthetic planet populations\
 , where we tested two independent generators (occurrence-weighted P-Pop an
 d a flat uniform-parameter control). The two scenarios are then pushed thr
 ough calibrated Kepler\, TESS\, and HARPS/NIRPS detection pipelines\, and 
 compared against the NASA Exoplanet Archive\, filtered with precision cont
 rol ≤25% mass/≤8% radius uncertainty (125 planets after the filter). T
 he analysis in comparison with NASA include a forward Monte Carlo comparis
 on and a Bayesian posterior-predictive test\, during which we used a metri
 c based on the detected population's rocky-to-volatile fraction. As for th
 e result\, at low insolation (S < 50 I⊕)\, the 25 NASA cold super-Earths
  favor Sub-Neptune under every relation and both generators (√x = 2.10 v
 s 6.25 in the Bayesian test). An important thing to note is that absolute 
 completeness of detection in this cold regime is only ~1%\, driven almost 
 entirely by the ~2% geometric transit probability of long orbits\, rather 
 than photometric sensitivity\, so the raw scarcity of cold rocky planets a
 lone says nothing until assessed in detected space. We also finds that the
  result fails when the uncertainty control is relaxed from ≤25% mass/≤
 8% radius  to ≤30% mass/≤10%\, and only 4 of 25 cold super-Earths are 
 rocky at high confidence. In conclusion\, we read the result as most rocky
  super-Earths coming from atmospheric escape rather than being born rocky.
  We believe that identifing more precise cold-planet masses\, concentrated
  among K/M dwarfs\, where detection efficiency stays near 50%\, are needed
  to settle it.\n\nhttps://nyx.physics.mcgill.ca/event/587/contributions/36
 69/
LOCATION:Online 
URL:https://nyx.physics.mcgill.ca/event/587/contributions/3669/
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