Identification of M giants in LAMOST DR5 · [CaH2+CaH3, TiO5] [J-H,H-K] Separation method The...
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Identification of M giants in LAMOST DR5 Jing Zhong（钟靖），Jing Li （李静）, Jeffrey L. Carlin, Li Chen （陈⼒） Shanghai Astronomical Observatory Zhong et al. 2019, ApJS, 244, 8
Transcript of Identification of M giants in LAMOST DR5 · [CaH2+CaH3, TiO5] [J-H,H-K] Separation method The...
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IdentificationofMgiantsinLAMOSTDR5
Jing Zhong（钟靖），Jing Li （李静）, Jeffrey L. Carlin, Li Chen （陈⼒）
Shanghai Astronomical Observatory
Zhongetal.2019,ApJS,244,8
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M giants are good tracers to study the substructures and the accretion history of the MW.
Luminousstars Distanttracers
EvolvedstarsWidedistribution
25kpc
M giant
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SDSS
LAMOST
Westetal.2011
DR770841Mdwarfs
coveyetal.2008
DR61squaredegree8750Mdwarfs~1%(104)
~0.5%(354)
Giantfraction
Bessell &Brett(1988)
H2OabsorptioninMdwarf/giantatmospheresaredifferent
Yietal.2014
Pilot58360Mdwarfs
Zhongetal.2015
DR1107193Mdwarfs8639Mgiants
~4%(2334)
~6.9%(8639)
[Mg2,g-r]
[CaH2+CaH3,TiO5]
[J-H,H-K]
Separationmethod
TheLAMOSThasgreatpotentialtoestablishalargestnumbersofMgiantsample
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• DR1---8639 MgiantLAMOST+WISE+2MASS
AnewcriteriaofselectingMgiantswithinfraredphotometryandanewphotometryrelationtoestimatethemetallicityforMgiants.Lietal.2016,ApJ,823,59
• DR2---17589MgiantLAMOST
NewtidaldebrisnearbytheSagittariusleadingtail。Lietal.2016,RAA,16,8• DR4---33000 MgiantLAMOST+WISE+Gaia
Weobtained164pureSgr streamstarsandfindthatthetrailingarmhashigherenergythantheleadingarminthesameangularmomentum,whichimplythattheSgr streammaycontainmultiplestellarpopulationswithabroadmetallicityrange. Lietal.2019,ApJ,874,178
MilkywaystudyusingtheMgiants
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M giantsample
BasedonthetemplatefittingmethodandtheM-typetemplatespectra，we
performedtheidentificationandclassificationofM-typestarsintheLAMOSTDR5,
andfound39796Mgiantsand501152 Mdwarfsintotal.
Zhong et al. 2015, AJ, 150, 42
Zhong et al. 2015, RAA, 15, 1154
TemplatefittingmethodMdwarfsMgiants𝜒" fitting
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TheseparationofMgiants&Mdwarfs
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ContaminationinMgiantssample Gaia+2mass+WISE
3Ddustmap:Greenetal.2018
Gaiadistance:Bailer-Jonesetal.2018Contaminationrate:4.4%
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ContaminationinMdwarfssample Gaia+2mass+WISE
3Ddustmap:Greenetal.2018
Gaiadistance:Bailer-Jonesetal.2018Contaminationrate:0.48%
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Misidentifiedspectra
• Early-typestarcandidates:mainsequence-Mgiantbinariesoreffectedbyabrightsourceinthenearbyfiber
• Whitedwarfs:whitedwarf–Mdwarfbinaries
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Carbonstars
Reddots:224commonstars,combiningwithMgiantscatalogandpublishedcarbonstarscatalog(Lietal.2018+Jietal.2016+Sietal.2015)
289confirmedcarbonstarsintheMgiantssample
ThespectralindicesCaH areefficientcriteriaforselectingcarbonstarsfromtheMgiantssample
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Carbonstarspectra
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ConfirmedM-typestars:ü LAMOSTspectraü Infraredcolor-colormagnitudeü Absolutemagnitudevs.BP-RPdiagram
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Halostars:5334,about14%ofourMgiantssample
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39,796Mgiants /501,152 M dwarfs
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Summary
• BasedonthetemplatefittingmethodandtheM-typetemplatespectra，weperformedtheidentificationandclassificationofM-typestarsintheLAMOSTDR5，atotalof39796Mgiants havebeencataloged.
• ArelativelypuresampleofMgiants(astrometry&photometry&spectroscopy)canbeusedtostudytheGalacticsubstructures(eg.,sagittarius stream).
Zhongetal.2019,ApJS,244,8
