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dc.contributor.authorRiaz, Basmah
dc.contributor.authorGizis, John E.
dc.date.accessioned2011-12-21T10:01:12Z
dc.date.available2011-12-21T10:01:12Z
dc.date.issued2007-04-10
dc.identifier.citationRiaz , B & Gizis , J E 2007 , ' Infrared Observations of a Mid-L Dwarf with Strong Hα Emission ' , The Astrophysical Journal , vol. 659 , no. 1 , pp. 675-679 . https://doi.org/10.1086/512065
dc.identifier.issn0004-637X
dc.identifier.otherPURE: 493653
dc.identifier.otherPURE UUID: 68b9dece-de64-4ec0-8a9f-d3b2f71b2526
dc.identifier.otherWOS: 000245773300055
dc.identifier.otherScopus: 34248220002
dc.identifier.urihttp://hdl.handle.net/2299/7445
dc.description.abstractWe present Spitzer/IRAC observations of the L5 dwarf, 2MASSI J1315309-264951 (2M 1315). This ultracool dwarf is known to display strong emission in the H alpha line. The spectral energy distribution (SED) for this object does not show any IR excess that would indicate the presence of an accretion disk. Although the IRAC colors for 2M 1315 are consistent with other L dwarfs, they seem to be redder by similar to 0.1 mag than the other L5 dwarfs, and more like the late-type L dwarfs. The existing six epochs of spectroscopy suggest that the emission in H alpha is not persistent, but shows long-term variability between a flare value of similar to 100 angstrom and a quiescent value of similar to 25 angstrom. Chromospheric activity seems to be the most likely cause, which is also indicated by the detection of Na I D lines in emission (Fuhrmeister et al.). We have measured a proper motion of 0.79 '' +/- 0.06 '' yr(-1), which corresponds to a tangential velocity of similar to 81 km s(-1) at a distance of similar to 22 pc. The high V-tan for this object suggests an old age. Evolutionary models indicate lower limits of 3.3 Gyr (Chabrier et al.) or 1.4 Gyr (Burrows et al.) for this magnetically active L dwarf to be a stable hydrogen burning star. There seem to be no observational differences between this old L dwarf that has H alpha emission and the other field L dwarfs withouten
dc.format.extent5
dc.language.isoeng
dc.relation.ispartofThe Astrophysical Journal
dc.rightsOpen
dc.subjectstars : activity
dc.subjectstars : chromospheres
dc.subjectstars : individual (2MASSI J1315309-264951)
dc.subjectstars : low-mass, brown dwarfs
dc.subjectTW-HYDRAE ASSOCIATION
dc.subjectLOW-MASS STARS
dc.subjectSPITZER-SPACE-TELESCOPE
dc.subjectBROWN DWARFS
dc.subjectMODEL ATMOSPHERES
dc.subject2MASS
dc.subjectKINEMATICS
dc.subjectPHOTOMETRY
dc.subjectSEQUENCE
dc.subjectMETHANE
dc.titleInfrared Observations of a Mid-L Dwarf with Strong Hα Emissionen
dc.contributor.institutionSchool of Physics, Astronomy and Mathematics
dc.contributor.institutionScience & Technology Research Institute
dc.contributor.institutionCentre for Astrophysics Research
dc.description.statusPeer reviewed
dc.relation.schoolSchool of Physics, Astronomy and Mathematics
dc.description.versiontypeFinal Accepted Version
dcterms.dateAccepted2007-04-10
rioxxterms.versionAM
rioxxterms.versionofrecordhttps://doi.org/10.1086/512065
rioxxterms.typeJournal Article/Review
herts.preservation.rarelyaccessedtrue
herts.rights.accesstypeOpen


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