Show simple item record

dc.contributor.authorJones, Hugh R. A.
dc.contributor.authorPavlenko, Yakiv
dc.contributor.authorLyubchik, Yuri
dc.contributor.authorBessell, Mike
dc.contributor.authorAllard, Nicole
dc.contributor.authorPinfield, David J.
dc.date.accessioned2023-05-17T15:45:01Z
dc.date.available2023-05-17T15:45:01Z
dc.date.issued2023-05-12
dc.identifier.citationJones , H R A , Pavlenko , Y , Lyubchik , Y , Bessell , M , Allard , N & Pinfield , D J 2023 , ' A blue depression in the optical spectra of M dwarfs ' , Monthly Notices of the Royal Astronomical Society . https://doi.org/10.1093/mnras/stad1391
dc.identifier.issn0035-8711
dc.identifier.otherArXiv: http://arxiv.org/abs/2304.09219v1
dc.identifier.urihttp://hdl.handle.net/2299/26342
dc.description© The Author(s) 2023. Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/).
dc.description.abstractA blue depression is found in the spectra of M dwarfs from 4000 to 4500A. This depression shows an increase toward lower temperatures though is particularly sensitive to gravity and metallicity. It is the single most sensitive feature in the optical spectra of M dwarfs. The depression appears as centered on the neutral calcium resonance line at 4227A and leads to nearby features being weaker by about two orders of magnitude than predicted. We consider a variety of possible causes for the depression including temperature, gravity, metallicity, dust, damping constants, and atmospheric stratification. We also consider relevant molecular opacities which might be the cause identifying AlH, SiH, and NaH in the spectral region. However, none of these solutions are satisfactory. In the absence of a more accurate determination of the broadening of the calcium line perturbed by molecular hydrogen, we find a promising empirical fit using a modified Lorentzian line profile for the calcium resonance line. Such fits provide a simplistic line-broadening description for this calcium resonance line and potentially other un-modelled resonance lines in cool high-pressure atmospheres. Thus we claim the most plausible cause of the blue depression in the optical spectra of M dwarfs is a lack of appropriate treatment of line broadening for atomic calcium. The broad wings of the calcium resonance line develop at temperatures below about 4000K and are analogous to the neutral sodium and potassium features which dominate the red optical spectra of L dwarfs.en
dc.format.extent14
dc.format.extent4351447
dc.language.isoeng
dc.relation.ispartofMonthly Notices of the Royal Astronomical Society
dc.subjectastro-ph.SR
dc.titleA blue depression in the optical spectra of M dwarfsen
dc.contributor.institutionCentre for Astrophysics Research (CAR)
dc.contributor.institutionSchool of Physics, Engineering & Computer Science
dc.contributor.institutionDepartment of Physics, Astronomy and Mathematics
dc.description.statusPeer reviewed
rioxxterms.versionofrecord10.1093/mnras/stad1391
rioxxterms.typeJournal Article/Review
herts.preservation.rarelyaccessedtrue


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record