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dc.contributor.authorBurningham, Ben
dc.contributor.authorMarley, Mark S.
dc.contributor.authorLine, Michael R.
dc.contributor.authorLupu, Roxana
dc.contributor.authorVisscher, Channon
dc.contributor.authorMorley, Caroline V.
dc.contributor.authorSaumon, Didier
dc.contributor.authorFreedman, Richard
dc.date.accessioned2019-02-21T10:08:00Z
dc.date.available2019-02-21T10:08:00Z
dc.date.issued2017-09-01
dc.identifier.citationBurningham , B , Marley , M S , Line , M R , Lupu , R , Visscher , C , Morley , C V , Saumon , D & Freedman , R 2017 , ' Retrieval of atmospheric properties of cloudy L dwarfs ' , Monthly Notices of the Royal Astronomical Society , vol. 470 , no. 1 , pp. 1177-1197 . https://doi.org/10.1093/mnras/stx1246
dc.identifier.issn0035-8711
dc.identifier.otherPURE: 11837065
dc.identifier.otherPURE UUID: 4781f234-f342-4172-8b0d-ee0b24e6b8e5
dc.identifier.otherArXiv: http://arxiv.org/abs/1701.01257v2
dc.identifier.otherScopus: 85030790045
dc.identifier.urihttp://hdl.handle.net/2299/21129
dc.description© 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.
dc.description.abstractWe present the first results from applying the spectral inversion technique in the cloudy L dwarf regime. Our new framework provides a flexible approach to modelling cloud opacity which can be built incrementally as the data requires, and improves upon previous retrieval experiments in the brown dwarf regime by allowing for scattering in two stream radiative transfer. Our first application of the tool to two mid-L dwarfs is able to reproduce their near-infrared spectra far more closely than grid models. Our retrieved thermal, chemical, and cloud profiles allow us to estimate $T_{\rm eff} = 1796^{+23}_{-25}$ K and $\log g = 5.21^{+0.05}_{-0.08}$ for 2MASS J05002100+0330501 and for 2MASSW J2224438-015852 we find $T_{\rm eff} = 1723^{+18}_{-19}$ K and $\log g = 5.31^{+0.04}_{-0.08}$, in close agreement with previous empirical estimates. Our best model for both objects includes an optically thick cloud deck which passes $\tau_{cloud} \geq 1$ (looking down) at a pressure of around 5 bar. The temperature at this pressure is too high for silicate species to condense, and we argue that corundum and/or iron clouds are responsible for this cloud opacity. Our retrieved profiles are cooler at depth, and warmer at altitude than the forward grid models that we compare, and we argue that some form of heating mechanism may be at work in the upper atmospheres of these L dwarfs. We also identify anomalously high CO abundance in both targets, which does not correlate with the warmth of our upper atmospheres or our choice of cloud model, and find similarly anomalous alkali abundance for one of our targets. These anomalies may reflect unrecognised shortcomings in our retrieval model, or inaccuracies in our gas phase opacities.en
dc.language.isoeng
dc.relation.ispartofMonthly Notices of the Royal Astronomical Society
dc.rightsOpen
dc.subjectastro-ph.SR
dc.subjectastro-ph.EP
dc.titleRetrieval of atmospheric properties of cloudy L dwarfsen
dc.contributor.institutionCentre for Astrophysics Research
dc.contributor.institutionSchool of Physics, Astronomy and Mathematics
dc.description.statusPeer reviewed
dc.relation.schoolSchool of Physics, Astronomy and Mathematics
dc.description.versiontypeFinal Accepted Version
dcterms.dateAccepted2017-09-01
rioxxterms.versionAM
rioxxterms.versionAM
rioxxterms.versionofrecordhttps://doi.org/10.1093/mnras/stx1246
rioxxterms.typeJournal Article/Review
herts.preservation.rarelyaccessedtrue
herts.rights.accesstypeOpen


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