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dc.contributor.authorKesseli, Aurora Y.en_US
dc.contributor.authorDavy Kirkpatrick, J.en_US
dc.contributor.authorFajardo-Acosta, Sergio B.en_US
dc.contributor.authorPenny, Matthew T.en_US
dc.contributor.authorScott Gaudi, B.en_US
dc.contributor.authorVeyette, Marken_US
dc.contributor.authorBoeshaar, Patricia C.en_US
dc.contributor.authorHenderson, Calen B.en_US
dc.contributor.authorCushing, Michael C.en_US
dc.contributor.authorCalchi-Novati, Sebastianoen_US
dc.contributor.authorShvartzvald, Y.en_US
dc.contributor.authorMuirhead, Philip S.en_US
dc.date2018-10-15
dc.date.accessioned2019-05-02T18:28:14Z
dc.date.available2019-05-02T18:28:14Z
dc.date.issued2019-01-22
dc.identifier.citationAurora Y Kesseli, J Davy Kirkpatrick, Sergio B Fajardo-Acosta, Matthew T Penny, B Scott Gaudi, Mark Veyette, Patricia C Boeshaar, Calen B Henderson, Michael C Cushing, Sebastiano Calchi-Novati, Y Shvartzvald, Philip S Muirhead. 2019. "Radii of 88 M Subdwarfs and Updated Radius Relations for Low-metallicity M-dwarf Stars." The Astronomical Journal, Volume 157, Issue 2, pp. 63 - 63. https://doi.org/10.3847/1538-3881/aae982
dc.identifier.issn1538-3881
dc.identifier.urihttps://hdl.handle.net/2144/35319
dc.description.abstractM subdwarfs are low-metallicity M dwarfs that typically inhabit the halo population of the Galaxy. Metallicity controls the opacity of stellar atmospheres; in metal-poor stars, hydrostatic equilibrium is reached at a smaller radius, leading to smaller radii for a given effective temperature. We compile a sample of 88 stars that span spectral classes K7 to M6 and include stars with metallicity classes from solar-metallicity dwarf stars to the lowest metallicity ultra subdwarfs to test how metallicity changes the stellar radius. We fit models to Palomar Double Spectrograph (DBSP) optical spectra to derive effective temperatures (T_ eff) and we measure bolometric luminosities (L_ bol) by combining broad wavelength-coverage photometry with Gaia parallaxes. Radii are then computed by combining the T_ eff and L_ bol using the Stefan–Boltzman law. We find that for a given temperature, ultra subdwarfs can be as much as five times smaller than their solar-metallicity counterparts. We present color-radius and color-surface brightness relations that extend down to [Fe/H] of −2.0 dex, in order to aid the radius determination of M subdwarfs, which will be especially important for the WFIRST exoplanetary microlensing survey.en_US
dc.format.extentp. 63en_US
dc.language.isoen_US
dc.publisherAmerican Astronomical Societyen_US
dc.relation.ispartofThe Astronomical Journal
dc.subjectScience & technologyen_US
dc.subjectPhysical sciencesen_US
dc.subjectAstronomy & astrophysicsen_US
dc.subjectStars: abundancesen_US
dc.subjectStars: fundamental parametersen_US
dc.subjectSubdwarfsen_US
dc.subjectLow-mass starsen_US
dc.subjectBrown dwarfsen_US
dc.subjectClassificationen_US
dc.subjectSkyen_US
dc.subjectParametersen_US
dc.subjectDiscoveryen_US
dc.subjectModelsen_US
dc.subjectSizesen_US
dc.subjectAstronomical and space sciencesen_US
dc.titleRadii of 88 M subdwarfs and updated radius relations for low-metallicity M-dwarf starsen_US
dc.typeArticleen_US
dc.description.versionPublished versionen_US
dc.identifier.doi10.3847/1538-3881/aae982
pubs.elements-sourcemanual-entryen_US
pubs.notesEmbargo: No embargoen_US
pubs.organisational-groupBoston Universityen_US
pubs.organisational-groupBoston University, College of Arts & Sciencesen_US
pubs.organisational-groupBoston University, College of Arts & Sciences, Department of Astronomyen_US
pubs.publication-statusPublished onlineen_US
dc.date.online2019-01-21
dc.identifier.orcid0000-0002-0638-8822 (Muirhead, Philip S)
dc.identifier.mycv422443


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