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SUMMARY:Auto-differentiable high-resolution spectral model for exoplanets 
 and its application to the Barnard's Star
DTSTART;VALUE=DATE-TIME:20220908T131500Z
DTEND;VALUE=DATE-TIME:20220908T133000Z
DTSTAMP;VALUE=DATE-TIME:20240704T115920Z
UID:indico-contribution-137@meetings.aip.de
DESCRIPTION:Speakers: Hiroyuki Tako Ishikawa (Astrobiology Center)\nWe are
  developing an open-source auto–differentiable spectral modeling code ["
 ExoJAX"](http://secondearths.sakura.ne.jp/exojax/#) to perform atmospheric
  retrieval for high-resolution exoplanetary spectra by ab initio spectral 
 fitting. This enables fully Bayesian inference of atmospheric parameters w
 ith the Hamiltonian Monte Carlo. Meanwhile\, the parameter estimation of M
  dwarfs\, which are important as host stars of various exoplanets\, has mo
 stly depended on pre-computed radiative-chemical equilibrium models. Howev
 er\, it has been reported in many literatures that the incompleteness of t
 hose models is a fundamental problem due to the spectral complexity caused
  by the cool atmosphere. We have retrieved the atmospheric parameters of t
 he well-known M dwarf Barnard's star ($T_{\\mathrm{eff}} \\sim$ 3200 K) by
  applying the ExoJAX to its high-resolution near-infrared spectra ($R\\sim
 $ 80000\, $YJH$–band) independently of stellar models. We succeeded in r
 eproducing well the molecular and atomic lines simultaneously at several w
 avelengths\, and estimated the temperature-pressure profile and mixing rat
 ios of each atomic and molecular species.  Nevertheless\, at other wavelen
 gths\, we found that the same way could not reproduce the absorption featu
 res at all\, so we discuss the inaccuracy and missing absorption lines of 
 the latest line list. The inspection of atmospheric retrieval of M dwarfs\
 , for which is easier to obtain high-resolution spectra with high quality 
 than in exoplanets\, will highlight the path and caveats to accurate retri
 eval of exoplanets.\n\nhttps://meetings.aip.de/event/16/contributions/137/
LOCATION:Leibniz Institute for Astrophysics Potsdam (AIP) Lecture Hall
URL:https://meetings.aip.de/event/16/contributions/137/
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