1 Spectroscopic survey of LAMOST Yongheng Zhao (National Astronomical Observatories of China) On behalf of the LAMOST operation team

2 Outline LAMOST Spectroscopic Survey of LAMOST Spectra & stellar parameters LAMOST Sciences Summary

3 Structure of LAMOST

: Construction 2009 – 2011: Commissioning Oct – June 2012: Pilot survey Sep – June 2017: Regular survey

5 Commissioning stage June 2009 – Sep  2/3 slit (R=1800)  Progress in fiber positioning  Realistic survey limiting magnitude: r = 17.8 Scientific test observations  M31 area  Planetary nebulae  Kinematics + populations  Quasars beyond  Quasars  Metal-poor stars

6 Spectra of stars

7 Emission line galaxy r=19.90 z=0.06 Emission line galaxy r=19.90 z=0.09 Quasar r=19.14 z=2.40 K3 star r=19.40 WD star r=18.18

8 LAMOST Survey Pilot Survey  PDR: Regular survey  1st year: DR1 (2013.9)  2nd year: DR2 ( )  3rd year: st year 2nd year pilot

9 Spectral data PDR (1 yrs) DR1 (2 yrs) DR2 (3 yrs) Spectra717,6602,204,8604,158,038 stars648,8201,944,4063,796,583 galaxies2,72312,08237,849 quasars6215,0179,495 Stars (S/N>10)547,8681,721,7963,231,240 AFGK parameters373,4811,085,4042,165,200 1 M spectra / year

10 Stellar parameters (2,165,200 spectra in DR2) Exceeding the total number of currently known database; Largest stellar parameter catalogue so far

11 LAMOST 光谱巡天进展 Footprint of 455 million spectra of SNRs > 10 collected by 单位 （万） 观测截止日期总光谱数恒星光谱数 SNR > 10 恒星光谱数有参数恒星光谱数发布 / 释放日期 DR / DR / DR / DR /

12 质量控制 光谱数 达标率（ SNRs > 10 ） 先导巡天（ 2011—2012 ） 573, % 常规巡天第一年（ 2012—2013 ） 1,243, % 常规巡天第二年（ 2013—2014 ） 1,326, % 常规巡天第三年（ 2014—2015 ） 1,304, % 常规巡天第一年（ 2012—2013 ）常规巡天第二年（ 2013—2014 ） 常规巡天第 3 年（ 2014—2015 ） 反银心方向巡天 B 、 M 面板观测源和达标源星等分布比较

13 2D pipeline: sky subtraction Comparison with SDSS: Better in red band for same S/N 760 and 860 nm where large number of sky emission lines

14 Flux calibration: spectral accuracy Green solid line: median Green dashed lines: std.dev Red solid lines: examples Comparisons of multi- observations as well as with photometry show the final SEDs have an accuracy better than 12%. Xiang et al. 2014a, to be submitted

15 Comparison of LAMOST and SDSS spectra Low-extinction regionsHigh-extinction regions Black: LAMOST Red: SDSS DR7 Our approach of flux calibration yields better, more realistic SEDs than SDSS for high extinction fields.

16 Comparison with external data: Teff, log g, [Fe/H] Teff, log g and [Fe/H] are accurate to ~ 150 K, ~ 0.25 dex, 0.15 dex for FGK stars, respectively. The results of SDSS DR9 are systematically −105 K, 0.24 dex, 0.12 dex lower. Xiang et al. 2014b, to be submitted

17 Comparison with external data: radial velocities

18 Scientific papers 48 scientific papers published 38 under processing Papers with LAMOST data Papers with SDSS spectral data PDRDR1

19 Scientific results

20 White dwarf mass function & birth rate Rebassa Mansergas et al. in prep.

21 Binary fraction in field FGK stars Yuan et al., to be submittedGao et al., 2014 ApJ Letter

22 Based on 66,647 thin disk FGK dwarfs (4200 < Teff < 6800 K, 3.8 < log g < 5.0, e < 0.15) within 600 pc of the Sun. The largest sample hitherto confirms that VΘ~12km/s. Results from different sub-populations suggest that the local disk is well relaxed The Local Standard of Rest Huang et al., 2014a to be submitted

23 Carlin et al., 2013, ApJL Bulk motions of disk stars

24 Metallicity Gradients of the Galaxy The outer disc shows both radial & vertical metallicity gradients. The radial gradient flattens at |Z| > 1.1 kpc, and so does radial gradient at R > 10 kpc Xiang et al. 2014c, Gong et al. 2014, to be submitted

25 Collaboration with Kepler project 62,381 spectra observed  32,462 Kepler stars

26 LAMOST Sciences Proposed  Extra-galactic spectroscopic survey n Galaxy & QSO redshift survey  Stellar spectroscopic survey n Structure of the Galaxy & stellar physics  Cross identification of multi-waveband survey Present (2/3 slits ： R = 500  1800)  Galactic survey  Structure & evolution of the Galaxy  QSO & galaxy  Cross identification of multi-waveband survey

27 Spectroscopic surveys Projectaper.FoVfibersspectratimeline 2dF3.9m2o2o ,000 G dF1.2m6o6o ,304 S RAVE1.2m6o6o ,630 S SDSS-I/II2.5m3o3o 6401,270,000 G SDSS-III2.5m3o3o 6402,000,000 G LAMOST4m5o5o 40005,000,000 S DESI3.9m3o3o ,500,000 G 2018 ？ -

28 Galactic survey （ ） The Milky Way is the only grand-design barred spiral (disk) galaxy that the individual stars can be resolved and studied multi-dimensionally ( 6D phase space + chemical composition).

29 SDSS 、 LAMOST & Gaia

30 Stellar halo profile Xu et al. in prep.

31 Local dark matter density

32 Stellar kinematics

33 Scientific goals of the galactic survey The survey will deliver classification, Vr, Teff, log g, [Fe/H], [α/Fe] for ~5 millions of stars.  A magnitude-limited and (statistically) complete sample of ~3 M stars  Distributed in a contiguous area  Sampling a significant volume of the thin/thick disks and halo With GAIA data, yield a unique dataset to  Study the stellar populations, chemical composition, kinematics and structure of the thin/thick disks and halo  Identify tidal streams & debris of disrupted dwarfs and clusters  Probe the gravitational potential and dark matter distribution  Map the interstellar extinction as a function of distance  Search for rare objects (e.g. stars of peculiar chemical composition or of hyper-velocities)  Ultimately advance our understanding of the assemblage history of the Milky Way, and of galaxies in general and their regularity and diversity.

34 Data policy of LAMOST Internal release  Chinese astronomers  International collaborators (with Chinese groups)  DR1 ( ) : 1.8 M spectra / 1.0 M parameters  DR2 ( ): 3.0 M spectra / 2.1 M parameters  DR3 ( ): 4.5 M spectra / 3.0 M parameters Public release （ after 1.5 yrs)  DR1 ( ) : 1.8 M spectra / 1.0 M parameters  DR2 ( ): 3.0 M spectra / 2.1 M parameters Collaboration on LAMOST Sciences

35 Thank You ！