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Spectroscopic survey of LAMOST

Yongheng Zhao(National Astronomical Observatories of China)

On behalf of the LAMOST operation team

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Outline

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

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Structure of LAMOST

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1997-2008: Construction2009 – 2011: Commissioning Oct. 2011 – June 2012: Pilot surveySep. 2012 – June 2017: Regular survey

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Commissioning stage

June 2009 – Sep. 2011 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

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Spectra of stars

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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

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LAMOST Survey

Pilot Survey 2011.10-2012.6

PDR: 2012.8

Regular survey 1st year: 2012.9-2013.6

DR1 (2013.9) 2nd year: 2013.9-2014.6

DR2 (2014.12) 3rd year: 2014.9-2015.6

1st year

2nd year

pilot

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Spectral data

PDR(1 yrs)

DR1(2 yrs)

DR2(3 yrs)

Spectra 717,660 2,204,860 4,158,038

stars 648,820 1,944,406 3,796,583

galaxies 2,723 12,082 37,849

quasars 621 5,017 9,495

Stars (S/N>10) 547,868 1,721,796 3,231,240

AFGK parameters 373,481 1,085,404 2,165,200

1 M spectra / year

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Stellar parameters (2,165,200 spectra in DR2)

Exceeding the total number of currently known database;

Largest stellar parameter catalogue so far

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LAMOST光谱巡天进展

Footprint of 455 million spectra of SNRs > 10 collected by 2015.06

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

DR0 20120617 92 82 61 39 2012.08/2012.08

DR1 20130603 220 194 180 106 2013.09/2015.03

DR2 20140603 414 378 322 221 2014.12/2016.07

DR3 20150602 574 520 455 296 2015.12/2017.07

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质量控制

光谱数 达标率（ SNRs > 10）

先导巡天（ 2011—2012 ） 573,227 48.4%常规巡天第一年（ 2012—2013 ） 1,243,478 62.7%常规巡天第二年（ 2013—2014 ） 1,326,700 72.4%常规巡天第三年（ 2014—2015 ） 1,304,925 71.8%

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

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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

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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

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Comparison of LAMOST and SDSS spectra

Low-extinction regions High-extinction regions

Black: LAMOST Red: SDSS DR7

Our approach of flux calibration yields better, more realistic SEDs than SDSS for high extinction fields.

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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

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Comparison with external data: radial velocities

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Scientific papers

48 scientific papers published 38 under processing

Papers with LAMOST data

Papers with SDSS spectral data

PDR DR1

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Scientific results

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White dwarf mass function & birth rate

Rebassa Mansergas et al. in prep.

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Binary fraction in field FGK stars

Yuan et al., to be submittedGao et al., 2014 ApJ Letter

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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

23Carlin et al., 2013, ApJL

Bulk motions of disk stars

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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

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Collaboration with Kepler project

62,381 spectra observed 32,462 Kepler stars

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LAMOST Sciences Proposed

Extra-galactic spectroscopic surveyn 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

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Spectroscopic surveys

Project aper. FoV fibers spectra timeline

2dF 3.9m 2o 400 250,000 G 1997-2002

6dF 1.2m 6o 150 136,304 S 2002-2004

RAVE 1.2m 6o 150 574,630 S 2006-2013

SDSS-I/II 2.5m 3o 640 1,270,000 G 2000-2008

SDSS-III 2.5m 3o 640 2,000,000 G 2008-2014

LAMOST 4m 5o 4000 5,000,000 S 2012-2017

DESI 3.9m 3o 5000 24,500,000 G 2018 ？ -

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Galactic survey （ 2012-2017）

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).

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SDSS 、 LAMOST & Gaia

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Stellar halo profile

Xu et al. in prep.

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Local dark matter density

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Stellar kinematics

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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.

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Data policy of LAMOST

Internal release Chinese astronomers International collaborators (with Chinese groups)

DR1 (2013.09) : 1.8 M spectra / 1.0 M parameters DR2 (2014.12): 3.0 M spectra / 2.1 M parameters DR3 (2015.12): 4.5 M spectra / 3.0 M parameters

Public release （ after 1.5 yrs) DR1 (2015.03) : 1.8 M spectra / 1.0 M parameters DR2 (2016.06): 3.0 M spectra / 2.1 M parameters

Collaboration on LAMOST Sciences

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Thank You！