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
M giants are good tracers to study the substructures and the accretion history of the MW.
Luminousstars Distanttracers
EvolvedstarsWidedistribution
25kpc
M giant
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
• 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
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
TheseparationofMgiants&Mdwarfs
ContaminationinMgiantssample Gaia+2mass+WISE
3Ddustmap:Greenetal.2018
Gaiadistance:Bailer-Jonesetal.2018Contaminationrate:4.4%
ContaminationinMdwarfssample Gaia+2mass+WISE
3Ddustmap:Greenetal.2018
Gaiadistance:Bailer-Jonesetal.2018Contaminationrate:0.48%
Misidentifiedspectra
• Early-typestarcandidates:mainsequence-Mgiantbinariesoreffectedbyabrightsourceinthenearbyfiber
• Whitedwarfs:whitedwarf–Mdwarfbinaries
Carbonstars
Reddots:224commonstars,combiningwithMgiantscatalogandpublishedcarbonstarscatalog(Lietal.2018+Jietal.2016+Sietal.2015)
289confirmedcarbonstarsintheMgiantssample
ThespectralindicesCaH areefficientcriteriaforselectingcarbonstarsfromtheMgiantssample
Carbonstarspectra
ConfirmedM-typestars:ü LAMOSTspectraü Infraredcolor-colormagnitudeü Absolutemagnitudevs.BP-RPdiagram
Halostars:5334,about14%ofourMgiantssample
39,796Mgiants /501,152 M dwarfs
Summary
• BasedonthetemplatefittingmethodandtheM-typetemplatespectra,weperformedtheidentificationandclassificationofM-typestarsintheLAMOSTDR5,atotalof39796Mgiants havebeencataloged.
• ArelativelypuresampleofMgiants(astrometry&photometry&spectroscopy)canbeusedtostudytheGalacticsubstructures(eg.,sagittarius stream).
Zhongetal.2019,ApJS,244,8