KIAA-CambridgeJoint Workshop on Near-Field Cosmology and Galactic Archeology ZHAO Gang National Astronomical Observatories, Chinese Academy of Sciences Dec 1-5, 2008 Beijing
Outline LAMOST stellar spectroscopic survey Distribution and spectral analysis of stars from different populations Extremely metal-poor stars and MDF Searching for planetary host stars c.f. Zhao et al. 2006, ChJA&A, 6, 265 Stellar Abundance and Galactic Chemical Evolution through LAMOST Spectroscopic Survey
Resolution powers Low-resolution mode Medium-resolution mode 3700 9000 Å R ~ 1000 / 2000 5100 5500 Å 8300 8900 Å R ~ 5000 / 10000
Distance limitation of LAMOST stellar spectroscopic survey Halo Bulge Galactic Center Sun Thick Disk Thin Disk Orbit of Halo star G0V: d = 2.13kpc (MRS, V=16), d = 13.79kpc (LRS,V=20) K5III: d = 17.4kpc (MRS, V=16), d = 109.6kpc (LRS,V=20)
Distribution of different populations Chemical Signatures Kinematical distributions
The Chemical Evolution of different Galactic populations Nissen (2004,oee symp.154) Gilmore & Wyse (1998,AJ, 116, 748)
Different kinematical characteristics of Galactic populations Nordstrom et al. (2004) Soubiran & Giard (2005)
[Fe/H] versus Age Karatas et al. (2005,MN, 360, 1345) Bensby et al. (2004)
Reid et al. (2007) Relation Between Age and Metallicity Reid et al. (2007, ApJ)
[Fe/H] versus R GC Nordstrom et al. (2004) Ivezic et al. (2008):SDSS data
Abundance and Kinematics Stellar Streams, moving groups Eggen (1998)
Klement, Fuchs & Rix, astro-ph/0805.2954v1.pdf
Continuing Combine with GAIA proper motion and parallax data, it is possible to construct the kinematical and abundance distribution with LAMOST spectra of a large sample of Galactic stars Clarification of exist of outer halo and inner halo
Search for metal-poor stars and MDF Spectroscopic survey Abundance analysis Sneden et al. (2003)
Continuing Observation features of LAMOST 5500 deg 2 of the northern sky (depth of B = 18 m.5) Much higher observation efficiency (4000 one time) Blue arm covers the CaII K determine MDF of the Galactic halo
method Candidate: B V color (measured from HES spectra with accuracy of 0.1 mag) in appropriate range, i.e., 0.3 < B V < 1.2 Ca K line weaker than expected for B V color of the given star and [Fe/H] = 2.5
Continuing Sample selection as input cat. SDSS-DR6 photometric catalogue star database Magnitude limit 14 < B < 18.5 Color selection 0.1 < g-r < 1.0 (4000K < T eff < 7000K) High Galactic latitude (b>45 ) A preliminary sample of 2,351,924 stars, to reach a deeper and further understanding of the Galactic stellar composition 2008-12-2 18
Continuing Further criterion for LAMOST/LRS spectra KP, HP2, CaT Scientific expectation Increase the number of metal-poor stars by a magnitude Extremely metal-poor stars [Fe/H] < -3.0 ~2000 Hyper metal-poor stars [Fe/H] < -5.0 ~20 2008-12-2 19
Continuing Establish database of stellar atmospheric parameters mid-resolution spectral survey for stars with V 16: extremely metal-poor stars: [Fe/H] -3.0 spectral analysis of some interesting elements A sub-sample is to be selected for LAMOST commission observation in the coming year or two
Search for planetary host stars Search method New technology Fiber couplers τ Vis Fixeddeladisperse r Post- Interfer ometer 1995, the first detection of SWP with traditional RV technique
ET Working Principle Current Echelle method ET Interferometer method Line shift Computer Telescope ET Machine Computer Phase shift Doppler shift is derived from phase shift of the interferometer
Doppler sensitivity comparison σ σ fringe, ob echelle, ob ( λ ) fringe 1/ 2 ( λ ) 3/ 2 echelle λ: spectral resolution Echelle strongly depends on spectral resolution ET weakly depends on spectral resolution
Survey with LAMOST Searches F, G, K type stars (including main sequence and G and K giants) with V < 14-15 in the northern sky. Last three years with 7 days per month Repeat observations for the same targets with optimal designed mode
Advantage by comparing future SDSS Exoplanet project Sloan LAMOST Aperture 2.5 m 4.0 m Field of view 3 degree 5 degree Fiber numbers 44 800-1200 Limit V Mag 13 14-15 Resolution 6000 5000/10000 W_coverage 1000A 1000/500A
Doppler radial velocity sensitivity of LAMOST and Sloan ET in an hour exposure V magnitude Sloan 2.5m LAMOST 4m 8 1.9 m/s 1.2 m/s 9 2.3 m/s 1.4 m/s 10 4.8 m/s 3.0 m/s 11 7.4 m/s 4.6 m/s 12 11.8 m/s 7.4 m/s 13 18.6 m/s 11.6 m/s
Goals of Exoplanet Survey 300,000 targets are expected to be observed with average of three times for each target within three years We may detect 17,000-60,000 exoplanet candidates through LAMOST/MRS survey Find some earth-like planets candidates (with 1-3 m/s) Statistical study of planet host stars in different location, different populations with such large samples Follow-up observations of some interesting objects with LAMOST/HRS for bright stars and 10m telescopes for faint stars if possible
Summary Low-resolution mode Space distribution and spectral analysis of stars from different populations in the Milky Way Search for extremely metal-poor stars and construct Galactic MDF Medium-resolution mode Search for exo-planet systems