Stellar population Studies with Stellar population Studies with LAMOSTLAMOST

- - Chen BingChen Bing - - ContentsContents

• Galactic structure & EvolutionGalactic structure & Evolution

• Related ProjectsRelated Projects

(SDSS/SUGUE, RAVE, AAOmage, GAIA)(SDSS/SUGUE, RAVE, AAOmage, GAIA)

• Collaboration & ProposalCollaboration & Proposal

Galactic structureGalactic structure

Thin DiskThin Disk

color-magnitude diagram Hipparcos; Density law Double exponential color-magnitude diagram Hipparcos; Density law Double exponential

Scale length/Scale height 2250/350 pcScale length/Scale height 2250/350 pc

Age=(0,10 Gyr), Fe/H =(0.01, -0.37 dex), d[Fe/H]/dR=-0.07 Age=(0,10 Gyr), Fe/H =(0.01, -0.37 dex), d[Fe/H]/dR=-0.07

(SigmaU, sigmaV, sigmaW) up to (43, 27, 17) km/s, Vad up to 15 km/s(SigmaU, sigmaV, sigmaW) up to (43, 27, 17) km/s, Vad up to 15 km/s

Thick DiskThick Disk color-magnitude diagram 47 Tuc; Density law Double exponential color-magnitude diagram 47 Tuc; Density law Double exponential Scale length/scale height 3500/750 pcScale length/scale height 3500/750 pc Age=11 Gyr, Fe/H = -0.78, d[Fe/H]/dR=0Age=11 Gyr, Fe/H = -0.78, d[Fe/H]/dR=0 (SigmaU, SigmaV, sigmaW) = (67, 51, 42) km/s, Vad= 53 km/s(SigmaU, SigmaV, sigmaW) = (67, 51, 42) km/s, Vad= 53 km/sHaloHalo

color-magnitude diagram M13, density law Power law, Axial ratio=0.55 color-magnitude diagram M13, density law Power law, Axial ratio=0.55

Age= 14 Gry, Fe/H=-1.78, d[Fe/H]/dR=0Age= 14 Gry, Fe/H=-1.78, d[Fe/H]/dR=0

(SigmaU, SigmaV, sigmaW) = (131, 106, 85) km/s, Vad= 226 km/s(SigmaU, SigmaV, sigmaW) = (131, 106, 85) km/s, Vad= 226 km/s

Bulge Bulge

Stellar streamsStellar streams,, Dark matterDark matter

Stellar populations in the GalaxyStellar populations in the Galaxy

A SDSS sample (run 752, 756), including 375693 objects

Simulated CMD with thick disk scale height of 1300 and 580 pc, respectively

Ages of Galactic disk and halo Ages of Galactic disk and halo

Globular cluster M4

Hansen et al., 2002

Age= 12.7 Gyr for M4

CMD for the Hipparcos data,Overlaid by isochrone fits

Jimenez et al. 1998

Isochrones are plotted for the Ages, 8, 11, 13, 15 Gyr, and Matallicities [Fe/H] = -0.5, 0.0, 0.3

Stars at the solar neighbourhoodStars at the solar neighbourhood

2df kinematic survey2df kinematic survey--The Anglo Australian Old stellar population SurveyThe Anglo Australian Old stellar population Survey--

Using 2df multi-object spectrograph

Spectral resolution 2.5 A

Velocity accuracy is 15 km/s

~ 2000 stars B-V < 0.7 V = 17.0 –19.5

2df kinematic survey 2df kinematic survey stars from a disrupted satellite galaxy ? stars from a disrupted satellite galaxy ?

Halo stream around the Milky wayHalo stream around the Milky way

The peculiar main-sequenceat a a distance of 11 kpc from the Sun in the direction of (l,b)=200,20)

Halo stream around the Milky wayHalo stream around the Milky way

500 SDSS spectroscopic radial velocities Have been taken

The tidal disruption of a galaxy By the Milky Way ?

Age-Metallicity-Kinematics at the solar neighborhoodAge-Metallicity-Kinematics at the solar neighborhood

Edvardsson et al. 1993

189 F/G main sequence stars

-1.0 < [Me/H] < 0.3

Stromgren photometry

high resolution spectra from

ESO 1.4 m & Mcdonald 2.7 m

Local dark matterLocal dark matterCreze et al. 1998

The local dynamical density comes out as 0.076 Msun/pc^3

The total mass density of stars and interstellar metter ~ 0.08 Msun/Pc^3

Conclusion: no room for disk shaped component of dark matter

The Thick disk – Halo InterfaceThe Thick disk – Halo Interface

2df metallicities vs radial velocity

Performance of survey Performance of survey telescopetelescope

Telescope Aperture Field of View ATelescope Aperture Field of View A** F F

Gemini 8.1 0.17 1.8Gemini 8.1 0.17 1.8

WHT 4.2 0.5 4.4WHT 4.2 0.5 4.4

VLT 8.1 0.4 10VLT 8.1 0.4 10

SDSS/SEGUE 2.4 2.5 36SDSS/SEGUE 2.4 2.5 36

2df/AAOmega 3.9 2.0 612df/AAOmega 3.9 2.0 61

6df/RAVE 1.2 6.6 656df/RAVE 1.2 6.6 65

LAMOST 4.0 5.0 400LAMOST 4.0 5.0 400

SDSS Multi-object SDSS Multi-object SpectrographsSpectrographs

End-to-end system throughput, including the telescope

The two SDSS spectrographs. The squareBlack openings accept the fiber opticsSlitheads, 320 fibers each.

SDSS Multi-object SDSS Multi-object SpectrographsSpectrographs

Number of spectrographs 2 Number of spectrographs 2

Spectral resolution 1800Spectral resolution 1800

Blue Channel range 3900-6000 Blue Channel range 3900-6000 A A

Red Channel range 6000-9100 Red Channel range 6000-9100 A

Fiber inputs per spectrograph 320Fiber inputs per spectrograph 320

Telescope aperture 2.5 mTelescope aperture 2.5 m

Fiber diameter 180 microns ( 3” ) Fiber diameter 180 microns ( 3” )

SDSS science plate targetsSDSS science plate targets

~ 500 galaxies, 100 QSO, and 30 stars~ 500 galaxies, 100 QSO, and 30 stars

SDSS key projectSDSS key project

redshifts for 10^6 galaxies and 10^5 quasarsredshifts for 10^6 galaxies and 10^5 quasars

SEGUESEGUE(Sloan Extension for Galactic underpinnings and (Sloan Extension for Galactic underpinnings and

Evolution)Evolution)The proposed Observing StrategyThe proposed Observing Strategy

• imaging ~ 3500 square degrees mostly at |b| < 30imaging ~ 3500 square degrees mostly at |b| < 30

• The spectroscopic targets from SDSS & SEGUEThe spectroscopic targets from SDSS & SEGUE

170 well-selected sky directions170 well-selected sky directions

Two plates in each field, one normal exposure plate, and one double-length plate to a limit of Two plates in each field, one normal exposure plate, and one double-length plate to a limit of g=20.3g=20.3

SEGUE imaging and SEGUE imaging and spectroscopic observing spectroscopic observing

planplan

Allocation of fibers per plate Allocation of fibers per plate pair pair

• 25 White dwarfs25 White dwarfs

• 175 Blue Horizontal Branch, F-turnoff stars175 Blue Horizontal Branch, F-turnoff stars

• 375 G dwarfs375 G dwarfs

• 200 K giant200 K giant

• 200 Low-metallicity candidates200 Low-metallicity candidates

• 175 M and K dwarfs175 M and K dwarfs

• 130 sky fibers and calibration standards130 sky fibers and calibration standards

To an accuracy To an accuracy RVs TRVs Teff log g [Fe/H]eff log g [Fe/H]

7 km/s 100-150 K 0.3-0.5 dex 0.25-0.3 dex7 km/s 100-150 K 0.3-0.5 dex 0.25-0.3 dex

RAVERAVE(Radial Velocity Experiment)(Radial Velocity Experiment)

Using the 1.2-m UK Schmidt telescope of the Using the 1.2-m UK Schmidt telescope of the AAOAAO, ,

Observing strategy (Observing strategy (use of the Ca-triplet at 8400-use of the Ca-triplet at 8400-8750, RVs better than 2 km/s)8750, RVs better than 2 km/s)

• Pilot survey (2003-2005) bright-time at the 6df Pilot survey (2003-2005) bright-time at the 6df

using the existing 150-fibre 6df system, 7” diameterusing the existing 150-fibre 6df system, 7” diameter

• Main Survey (2006-2010)Main Survey (2006-2010) will use the proposed 2250 fibre systemwill use the proposed 2250 fibre system

50 million stars, magnitude limited (V=16), all sky 50 million stars, magnitude limited (V=16), all sky surveysurvey

looking for a northern counterpartlooking for a northern counterpart

AAOmega AAOmega A 3.9 m telescope providing a general purpose spectroscopic A 3.9 m telescope providing a general purpose spectroscopic

facilityfacility

AAOmega – multiple-object modeAAOmega – multiple-object mode

• Field of view 2 degreesField of view 2 degrees

• Number of fibres 350-392 Number of fibres 350-392

• Angular size of fibre 2”Angular size of fibre 2”

• Wavelength range 3700 –9500 AWavelength range 3700 –9500 A

• Peak system throughput (Blue/Red) 0.17/0.20Peak system throughput (Blue/Red) 0.17/0.20

• Spectrl resolution 1300 – 8000Spectrl resolution 1300 – 8000

• Spectral resolution 3.5 ASpectral resolution 3.5 A

• Limiting mag B=22.0Limiting mag B=22.0

AAOmega Galaxy Science AAOmega Galaxy Science

Still under investigation, proposal Still under investigation, proposal includingincluding

• Large AAOmega + RAVE stellar population surveyLarge AAOmega + RAVE stellar population survey

• Halo structures, Thick disk metallicity – kinematicsHalo structures, Thick disk metallicity – kinematics

• DM distributionDM distribution

Input Catalogues exist (2MASS, …)Input Catalogues exist (2MASS, …)

Complement SEGUE, LAMOST in the north ..Complement SEGUE, LAMOST in the north ..

GAIA – ESA only missionGAIA – ESA only mission

GAIA GAIA

• Astrometry (V < 20)Astrometry (V < 20)

• Radial velocity ( V < 16-17)Radial velocity ( V < 16-17)

Third component of space motionThird component of space motion

• Photometry ( V < 20) Photometry ( V < 20)

A Complete survey, launch date 2010-A Complete survey, launch date 2010-2012,2012,

+ 5 year observations, final catalog ~ + 5 year observations, final catalog ~ 20182018

DIVADIVA German national Space science missionGerman national Space science mission

• Magnitude limited all-sky surveys (V =15-Magnitude limited all-sky surveys (V =15-16), a mission between Hipparcos & 16), a mission between Hipparcos & GAIAGAIA

• DIVA and RAVE complement each other. DIVA and RAVE complement each other.

permit to determine the full 6-D permit to determine the full 6-D distributiondistribution

• CANCELLEDCANCELLED !! !! unable to close the funding gap of ~ 15 million EUROunable to close the funding gap of ~ 15 million EURO

• A big loss for RAVE, and its scienceA big loss for RAVE, and its science

Collaboration & ProposalCollaboration & Proposal

Spectroscopic surveys for stars are important (RAVE, AAOmega, SEGUE)

RAVE 1) Have a clear Science goal, magnitude limited survey (V=16) 2) looking for a collaboration in north (LAMOST is an option) 3) Science quality is reduced after DIVA was cancelled 4) GAIA final catalog ~ 2018

AAOmega 1) A telescope comparable with LAMOST 2) Science goals not yet decided

3) A general facility for all sciences

,

One ProposalOne Proposal

Observing all SDSS/SEGUE stellar objects between V=17~20 mag

4000 Fibres/field * 7 fields/night * 200 nights/year = 5.6 million stars/ year • It can be finished before the launch of GAIA (probably 2012)

• Successful 2df kinematic survey

• Data can serve the whole community in our lifetime

• Stars observed include thin disk, thick disk, halo, stellar streams, … many sciences can be done

• possible collaboration with GAIA mission

,

Comments from Brian Yanny (SEGUE leader)Comments from Brian Yanny (SEGUE leader) “ I think this is an excellent project for LAMOST ”

“I understand that the resolution might be a bit worse, but even if your resolution is R ~ 1000, you should be able to do radial velocities to 30 km/s, if one is careful about calibration”

“I would push them to think about their resolution and calibration schemes on their LAMOST spectrograph so that they may be able to get good radial velocities for many stars ”

“I agree that LAMOST will be especially unique in getting velocities of faint stars, down to 20th magnitude or so, and in that way be complementary to a project such as GAIA which will get spectra for only brighter objects”

,

My traces abroadMy traces abroad

•1989-1993, Ph.D, SIMBAD/CDS, France1989-1993, Ph.D, SIMBAD/CDS, France

multi-color star count survey multi-color star count survey

•1994-1999, Postdoc, Barcelona Spain1994-1999, Postdoc, Barcelona Spain

Hipparcos & GAIAHipparcos & GAIA•1999-2001, SDSS, Johns Hopkins USA1999-2001, SDSS, Johns Hopkins USA

SDSSSDSS •2001-now, XMM Madrid/ESA Spain2001-now, XMM Madrid/ESA Spain

XMMXMM