The Large Sky Area Multi- Object Spectroscopic Telescope (LAMOST)

The Large Sky Area Multi- Object Spectroscopic Telescope (LAMOST) The Milky Way and its Stars February 25 KITP!! Martin C. Smith Shanghai Astronomical Observatory http://hubble.shao.ac.cn/~msmith/

LAMOST introduction China s largest optical telescope A 4-5m telescope with 4 fibers across a 2 sq deg field of view, at R = 2, Full surveys started in 22, obtaining over M good stellar spectra (S/N > ) each year, current total of over 3M spectra Fields cover halo/disc/anti-centre, with ancillary projects such as LAMOST-Kepler led by Fu & De Cat (~6k good spectra in the Kepler field) Five-year survey, with possibility of higher-resolution (R=5,-,) in future

B M F 7 57 KEPLER 6 78 Total 526 757 Plate Spe r LAMOST introduction China s largest optical telescope A 4-5m telescope with 4 fibers across a 2 sq deg field of view, at R = 2, Full surveys started in 22, obtaining over M good stellar spectra (S/N > ) each year, current total of over 3M spectra Fields cover halo/disc/anti-centre, with ancillary projects such as 29 6275 34 LAMOST-Kepler led by Fu & http://vega.bac.pku.edu.cn/astro/astro.htm De Cat (~6k good spectra in the Kepler field) Five-year survey, with possibility of higher-resolution (R=5,-,) in future GAC 69 9 M3 25 3 V 283 3 EG 4 5 HD 62 2 B M F 95 KEPLER 2 Total 676 9 6275 http://kiaa.pku.edu.cn/

Overview of data quality Success rate (S/N > ) around 7%, with a limiting magnitude of r ~ 7, so great synergy with Gaia 2nd Full survey year Regular 2nd year Survey data Very bright plates 9 < V < 4 observed Pipelines in place, with 2.2M FGK stars with parameters from first two years Similar accuracy to SDSS (~.5 dex in [Fe/H], ~.2 dex in log(g), ~K in T eff ) although issues with gravities Various plans to estimate alphas, although not currently implemented r-band magnitude

Overview of data quality Success rate (S/N > ) around 7%, with a limiting magnitude of r ~ 7, so great synergy with Gaia Comparison to SDSS (Yue Wu) 2nd Full survey year Regular 2nd year Survey data Very bright plates 9 < V < 4 observed Pipelines in place, with 2.2M FGK stars with parameters from first two years Similar accuracy to SDSS (~.5 dex in [Fe/H], ~.2 dex in log(g), ~K in T eff ) although issues with gravities Various plans to estimate alphas, although not currently implemented r-band magnitude

Overview of data quality ( S SVM V R ) -vs l ogg (L M ) log(g)l ogg oﬀset Seism. log(g) oﬀset vs (LAMOST l ogg (Seism. S V R ) - l ogg LM) 28). Second, the other features, e.g., Balmer lines (Wilhelm, Beers & Gray 999), CaII K 2 and H lines (Lee et al. 28) etc., can also be l ogg ( S V R ) - l ogg ( L M ) useful to determine the surface gravity. Morem e d i an l ogg ( S V R ) - l ogg ( L M ).5 over, some algorithms determine the surface gravity together with the eﬀective temperature and metallicity, simultaneously, by comparing Improvements in survey depths and with success rates the full spectra the spectral library (e.g.,.5 Lee et al. 28; Wu et al. 2a). In addition, Comparison SDSSapproaches, (Yue Wu) e.g. the supervised machine to learning Full survey 2ndsupport yearsurvey data st year Regular Survey 2nd year Regular artificial neural networks, vector ma Success rate (S/N > ) around chine etc., have also been used to derive the.5 observed observed Very bright plates 7%, with a limiting magnitude of surface gravity based on the training spectra 9 < V < 4 with known surface gravity values as the tarr ~ 7, so great synergy with Gaia gets (Re Fiorentin et al. 27; Liu et al. 22)..5 The typical accuracy of the surface gravity es Pipelines in place, with 2.2M FGK LAMOST Kepler (Liu et al.spectra, 25) e.g. SDSS timates +for low resolution 2 stars with from first 4 parameters 2 3 (Ahn et al. 24) or LAMOST (Cui et al. 22), l ogg ( S V R ) is about.2-.4 dex (Wilhelm, Beers & Gray log(g) from Seismology two years.5 o ﬀ se t =et.al. 28; 999; Re Fiorentin et al. 27; Lee Fig. 2. The comparison between the SVR and σ =. 3 Wu et al. 24). Similarlogg accuracy to dataset SDSS (the (~.5 the LAMOST for the test black s t d d etool v =. Asteroseismology is a powerful to2derive.5 dots). dex The in red[fe/h], filled circles bars ~.2with dexthe in error log(g), the fundamental parameters, e.g. stellar mass, raare the median values and σ dispersions of the dius, and Teﬀ, for a star (see Brown & Gilliland ~K in Teff) although issues diﬀerence of logg at each logg(sv R) bin..5 994; Chaplin & Migio 23). Thanks to the with gravities Kepler (Borucki et al. 2) mission, the Sun like oscillations for tens of thousands of stars Various plans to estimate alphas,.5 (b ) ((ca) ) ( d()b ) although not currently implemented 3.65 3.7 Te ﬀ (LM ) 3.75.6.4.2.2 [ Fe /H ] ( L M ).4 r-band magnitude 3.7 3.75.2 3 4.6.4.2 23.55 3.6 23.65 ogt (LM [ Fe /H ] ( L M ) l oggeseismology ( ast ) ) log(g) lfrom ﬀ 29 6275 34 http://vega.bac.pku.edu.cn/astro/astro.htm 6275 6692 http://kiaa.pku.edu.cn/ Fig. 3. for Thethe residual of the as SVR logg, logg(sv dual of the SVR logg, logg(sv R) logg(ast), test dataset functions of the R) lo

Science highlights Binaries (Gao et al. 24) & RR Lyrae (Yang et al. 24) K-giants (Liu et al. 24) Local UV-velocity distribution from 5, F/G dwarfs (Xia et al. 25) Repeat observations (per year) Distance papers (in prep) White dwarfs (Rebassa-Mansergas et al. in prep) M-type stars, incl. -3k giants (Zhong et al. in prep; Li et al. in prep) Other science: stellar physics; open clusters; ages & chemo-dynamical studies; HVS; dark matter density; chemically peculiar stars (e.g. Am, Li-rich, alpha-poor, metal-poor, etc)

Science highlights Binaries (Gao et al. 24) & RR Lyrae (Yang et al. 24) K-giants (Liu et al. 24) Local UV-velocity distribution from 5, F/G dwarfs (Xia et al. 25) Repeat observations (per year) Distance papers (in prep) White dwarfs (Rebassa-Mansergas et al. in prep).8 M-type stars, incl. -3k giants.6 (Zhong et al. in prep; Li et al. in prep) f B.4 Other science: stellar physics; open clusters; ages & chemo-dynamical.2 studies; HVS; dark matter density; chemically peculiar stars (e.g. Am, 75 7 65 6 55 Li-rich, alpha-poor, metal-poor, etc) SDSS SEGUE LAMOST LEGUE Gao et al. (24) SDSS SEGUE G/F subsample LAMOST LEGUE 7 T eff (K) 5 45 4 2 [Fe/H] 6

Science highlights Binaries (Gao et al. 24) & RR Lyrae (Yang et al. 24) K-giants (Liu et al. 24) Local UV-velocity distribution from 5, F/G dwarfs (Xia et al. 25) Repeat observations (per year) Qia et al. (25) Distance papers (in prep) White dwarfs (Rebassa-Mansergas et al. in prep) M-type stars, incl. -3k giants (Zhong et al. in prep; Li et al. in prep) Other science: stellar physics; open clusters; ages & chemo-dynamical studies; HVS; dark matter density; chemically peculiar stars (e.g. Am, Li-rich, alpha-poor, metal-poor, etc)

Science highlights Binaries (Gao et al. 24) & RR Lyrae (Yang et al. 24) K-giants (Liu et al. 24) Zhong et al. (in prep) Local UV-velocity distribution from 5, F/G dwarfs (Xia et al. 25) Distance papers (in prep) White dwarfs (Rebassa-Mansergas et al. in prep) M-type stars, incl. -3k giants (Zhong et al. in prep; Li et al. in prep) Other science: stellar physics; open clusters; ages & chemo-dynamical studies; HVS; dark matter density; chemically peculiar stars (e.g. Am, Li-rich, alpha-poor, metal-poor, etc)

Science highlights.6.4 Mdwarf Kgiant Li et al. (in prep) Kdwarf Binaries (Gao et al. 24) & RR Lyrae (Yang et al. 24) K-giants (Liu et al. 24) (J K).2.8.6 Zhong et al. (in prep) Local UV-velocity distribution from 5, F/G dwarfs (Xia et al. 25).4.2.2.2 (W W2).2.2 (W W2).2.2 (W W2) Distance papers (in prep) White dwarfs (Rebassa-Mansergas et al. in prep) M-type stars, incl. -3k giants (Zhong et al. in prep; Li et al. in prep) Other science: stellar physics; open clusters; ages & chemo-dynamical studies; HVS; dark matter density; chemically peculiar stars (e.g. Am, Li-rich, alpha-poor, metal-poor, etc) (J K).5.5 Kgiant Mdwarf Kdwarf.2...2.3 (W W2)

Science highlights.6.4 Mdwarf Kgiant Li et al. (in prep) Kdwarf Binaries (Gao et al. 24) & RR Lyrae (Yang et al. 24) K-giants (Liu et al. 24) Local UV-velocity distribution from 5, F/G 8 dwarfs (Xia et al. 25) Distance papers (in prep) White dwarfs (Rebassa-Mansergas et al. in prep) 2 dec 6 4 M-type stars, incl. -3k giants (Zhong et al. in prep; Li et al. in prep) 2 M-giants in WISE Other science: 4 stellar physics; open clusters; ages & chemo-dynamical 6 studies; HVS; dark matter density; chemically 8 peculiar stars (e.g. Am, Li-rich, alpha-poor, 35 3 metal-poor, 25 etc) 2 ra 5 (J K) (J K).2.8.6.4 Sagittarius stream.2.2.2 (W W2).5.5 Zhong et al. (in prep).2.2 (W W2).2.2 (W W2) Kgiant Mdwarf Kdwarf 5.2...2.3 (W W2)

2 Science highlights Li et al. (in prep) ~ B (deg).6 Mdwarf.4 Kgiant Kdwarf.2 Binaries (Gao et al. 24) & RR Lyrae (Yang et al. 24) - (J K) Zhong et al. (in prep).8-2 2.6 K-giants (Liu et al. 24).4 Distance papers (in prep) White dwarfs (Rebassa-Mansergas et al. in prep) M-type stars, incl. -3k giants (Zhong et al. in prep; Li et al. in prep) Other science: stellar physics; open clusters; ages & chemo-dynamical studies; HVS; dark matter density; chemically peculiar stars (e.g. Am, Li-rich, alpha-poor, metal-poor, etc) ~ B (deg).2.2.2 (W W2).2.2 (W W2).2.2 (W W2).5 Kgiant Mdwarf Kdwarf - -2 (J K) Local UV-velocity distribution from 5, F/G dwarfs (Xia et al. 25) Distance (kpc) 8 6.5 4 2.2.. (W W2)2 ~ Λ (deg).2.3 3

Li et al. (in prep) 2 6 2 Science highlights 4.2 & RR (Gao et al. 24) [Fe/H]phot [Fe/H]APOGEE Lyrae (Yang et al. 24) 2 K-giants.4 UV-velocity distribution from 5, F/G dwarfs (Xia et al. 25) 2-2.5-2 -.5 - -.5.5 4.2 Distance papers (in prep).5..5.5 (W W2) Other science: stellar physics; open clusters; ages & chemo-dynamical studies; HVS; dark matter density; chemically peculiar stars (e.g. Am, Li-rich, alpha-poor, metal-poor, etc) ~ B (deg).2.2 (W W2).2.2 (W W2).5.5 White dwarfs (Rebassa-Mansergas et al. in prep) M-type stars, incl. -3k giants (Zhong et al. in prep; Li et al. in prep).2 - -2 3 2.2 (W W2) (J K). Λ =8-2 (deg).2 Kdwarf Zhong et al. (in prep).8.4 3 Local Kgiant 5-2 2.6 (Liu et al. 24) Mdwarf Λ =3-7 (deg) - (J K) Binaries.6 Distance (kpc) [Fe/H]APOGEE ~ B (deg) 2 Li et al. (in prep) 8 6.5 4 2-2.5-2 -.5 - -.5 Kgiant.5 Λ =24-28 (deg) Mdwarf Kdwarf 3 2 Λ =29-33 (deg) -3-2.5-2 -.5 - -.5.5.2. [Fe/H]phot. (W W2)2 ~ Λ (deg).2.3 3

LAMOST summary Other projects Full survey is making good progress, obtaining over M stars each year to 7th mag Pipelines are relatively robust and continually being improved Large number of spectra for Kepler/K2 fields A lot of great science underway DR will be released internationally in March, including catalogues and spectra (.8M with S/N > ; M FGK star parameters) Hills & hypervelocity stars (Yanqiong Zhang & John Vickers -SHAO, Shanghai) Alphas & ages for LAMOST stars, starting with LAMOST-KEPLER (Emma Small & John Vickers - SHAO, Shanghai; Corrado Boeche - ARI, Heidelberg) Orbital structure of disc & bulge stars from N-body models, currently analysing the APOGEE bulge high-velocity peaks (Matthew Molloy - KIAA, Beijing) Outer-halo substructures using BHBs from deep u-band photometry, including a comprehensive characterisation of the Pisces over-density (Jundan Nie - NAOC, Beijing) Pulsar microlensing (Dai Shi - PKU, Beijing)

Discussion points What aspects of the data analysis would you like to see worked on? Alphas are being coming, as I have shown gravities can be calibrated (with caveats), but is there anything else? Future plans for LAMOST? The five year survey will end in Summer 27. What next? The higher-res grating is an option (see below), especially useful if this will provide reliable alpha-element abundances. Or time domain for binaries or variables? Or just keep going, making a complete survey of the disc. This is what they said back in 22 regarding the higher-resolution option: The survey will also include an R = 5-, mode, which will yield two pieces of the spectrum that are 35A wide, one in the red and one in the blue.the blue wavelength coverage is centered around 53A to sample many metal lines,including the prominent Mg b (575A) triplet. The red segment covers the spectral range 84-875A, sampling the CaII triplet, Fe I, Ti I, and other lines, which are ideal for measuring the RV and [Fe/H]. This R = 5 mode wavelength coverage and dispersion is similar to that of the RAVE experiment.