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