William Frost MSc UdeM In collaboration with Loïc Albert Ren é Doyon amp Björn Benneke Summary of Research Construct an emission spectrum of a brown dwarf BD from existing observations ID: 1046362
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1. Direct Test of Brown Dwarf Models Through Secondary Eclipse Spectroscopy of LHS 6343 CWilliam FrostMSc - UdeMIn collaboration withLoïc Albert, René Doyon & Björn Benneke
2. Summary of ResearchConstruct an emission spectrum of a brown dwarf (BD) from existing observationsDirectly measure its physical properties (e.g. mass, radius, luminosity) Compare these properties to atmospheric and evolutionary model predictions.
3. Brown DwarfsMasses of Unable to fuse hydrogen like starsCapable of lower tier reactionsDecrease luminosity over time “Nicht Stern, nicht Planet” , Max Planck Forschung 02/2014 G starM staryoungbrown dwarfoldbrown dwarfultra-coolbrown dwarfplanetStarsBrown DwarfsPlanets
4. Burrows et al. 2001 ---- : Stars---- : Brown Dwarfs---- : PlanetsLog 10 (Luminosity) (in solar units)Log 10 (Age) (Gyrs)
5.
6. Brown Dwarf Eclipsing Binaries (BDEBs)Can obtain RV, transit and eclipse signalsCan directly measure BD mass, radius, luminosity, temperatureHowever…Only ≈30 BDEB systems discovered so far.Even fewer are likely representative of field BDsMost are too young and/or too close to their companions ⇒ Inflated radii and luminosities
7. LHS 6343 C: The Chosen One!M-dwarf binary with a BD orbiting the primaryInitial discovery in 2011 by Kepler (Johnson et al.)Latest analysis from 2016 (Montet et al.)4 years of Kepler transits34 Keck/HIRES radial velocity observations4 Spitzer/IRAC (+ 1 Kepler) secondary transitsContributions from this research:1 HST/WFC3 secondary transit (Albert et al. 2015)Updated stellar parameters and system distanceKS -band photometry, Palomar/PHARO(Johnson et al. 2011)Brown dwarf in hiding36.5 AUM-dwarfsYields updated direct measures of mass and radius and measures are semi-direct (∼40% model dependance)
8. HST/WFC3 Analysis1st step: MCMC to fit the observed white-light curve Uniform priors on 8/14 params Literature constrains the rest2nd step: MCMC to fit the spectroscopic light curves
9. 27 SLCsUniform priors for 3/14 paramsFlux ratio Norm. constant (i.e. )Std. dev. in the data
10. LHS 6343 C - HST/WFC3 Relative Emission Spectum
11. LHS 6343 C - HST/WFC3 Emission Spectum
12. LHS 6343 C - Total Observed Emission SpectumKeplerHST/WFC3SpitzerIRAC1SpitzerIRAC2
13. Produced the emission spectrumDirect Measures:System Distance (GAIA E-DR3) Semi-Direct Measures Model-Dependent MeasuresAge LHS 6343 C Progress TrackerAtmospheric ModellingEvolutionary Modelling
14. Selection: ATMO-2020 and Sonora-Bobcat model gridsCloudless, self-consistent atmosphere and evolution gridsATMO-2020 (Phillips et al. 2020) :Solar metallicity, chemical equilibrium and non-equilibrium modelsSonora-Bobcat (Marley et al. 2021) :Varying metallicity, chemical equilibrium modelsBrown Dwarf ModellingPart 1: Model Selection
15. Objective ⇒ Measure and by integrating the observed SED of LHS 6343 C Because the SED is incomplete, we need models to produce spectra outside the Kepler, HST and Spitzer bandpasses.Strategy : Fit the model grids by constraining all physical parameters except Brown Dwarf ModellingPart 2: Atmospheric Model Fitting
16. Sonora-Bobcat Atmospheric Results Kepler HST/WFC3 Spitzer/IRAC1 Spitzer/IRAC2
17. ATMO-2020 resultsCEQNEQ (strong)NEQ (weak) Kepler HST/WFC3 Spitzer/IRAC1 Spitzer/IRAC2
18. Semi-Direct Measurements from Atmosphere ModellingValues produced from all models are similar Obtain from using the Stefan-Boltzmann Law
19. Evolutionary Model Interpolation Sonora Bobcat Models (solar metallicity)ATMO-2020 Models
20. SummaryField brown dwarf characterization is heavily dependent on atmospheric and evolutionary modelling.Brown dwarfs as eclipsing binaries (BDEBs) are powerful tools that can yield direct measures of most parameters.Our analysis of LHS 6343 C yields direct measures for mass, radius, and . These values can act as benchmarks for this BD’s spectral type.Recent model grids are successful in reproducing what was measured for LHS 6343 C