LAMOST Experiment for Galactic Understanding and Exploration (LEGUE) — The survey's science plan

Deng, Licai; Newberg, Heidi Jo; Liu, Chao; Carlin, Jeffrey L.; Beers, Timothy C.; Chen, Li; Chen, Yu Qin; Christlieb, N.; Grillmair, Carl J.; Guhathakurta, Puragra; Han, Zhan Wen; Hou, J. L.; Lee, Hsu Tai; Lépine, Sébastien; Li, Jing; Liu, Xiao Wei; Pan, K.; Sellwood, J. A.; Wang, Bo; Wang, Hong Chi; Yang, Fan; Yanny, B.; Zhang, Haotong; Zhang, Yue Yang; Zheng, Zheng; Zhu, Zi

doi:10.1088/1674-4527/12/7/003

Cited by 541 publications

(432 citation statements)

References 143 publications

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“…LSS-GAC is a major component of the on-going LAMOST Experiment for Galactic Understanding and Exploration (LEGUE; Deng et al 2012). LSS-GAC aims to collect optical (λλ3800-9000), low resolution (R ∼ 1800) spectra under dark and grey lunar conditions for a statistically complete sample of over three million stars of all colours and of magnitudes 14.0 r < 17.8 mag (18.5 mag for limited fields), in a continuous sky area of ∼ 3400 square degrees, centred on the GAC, covering Galactic longitudes 150 < l < 210 • and latitudes |b| < 30 • .…”

Section: Lss-gac Sdss/segue and Sdss-iii/apogee Datamentioning

confidence: 99%

The Milky Way's rotation curve out to 100 kpc and its constraint on the Galactic mass distribution

Huang

Liu

Yuan

et al. 2016

Mon. Not. R. Astron. Soc.

158

179

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The rotation curve (RC) of the Milky Way out to ∼ 100 kpc has been constructed using ∼ 16, 000 primary red clump giants (PRCGs) in the outer disk selected from the LSS-GAC and the SDSS-III/APOGEE survey, combined with ∼ 5700 halo K giants (HKGs) selected from the SDSS/SEGUE survey. To derive the RC, the PRCG sample of the warm disc population and the HKG sample of halo stellar population are respectively analyzed using a kinematical model allowing for the asymmetric drift corrections and re-analyzed using the spherical Jeans equation along with measurements of the anisotropic parameter β currently available. The typical uncertainties of RC derived from the PRCG and HKG samples are respectively 5-7 km s −1 and several tens km s −1 . We determine a circular velocity at the solar position, V c (R 0 ) = 240 ± 6 km s −1 and an azimuthal peculiar speed of the Sun, V ⊙ = 12.1 ± 7.6 km s −1 , both in good agreement with the previous determinations. The newly constructed RC has a generally flat value of 240 km s −1 within a Galactocentric distance r of 25 kpc and then decreases steadily to 150 km s −1 at r ∼ 100 kpc. On top of this overall trend, the RC exhibits two prominent localized dips, one at r ∼ 11 kpc and another at r ∼ 19 kpc. From the newly constructed RC, combined with other constraints, we have built a parametrized mass model for the Galaxy, yielding a virial mass of the Milky Way's dark matter halo of 0.90 +0.07 −0.08 × 10 12 M ⊙ and a local dark matter density, ρ ⊙,dm = 0.32 +0.02 −0.02 GeV cm −3 .

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Section: Lss-gac Sdss/segue and Sdss-iii/apogee Datamentioning

confidence: 99%

The Milky Way's rotation curve out to 100 kpc and its constraint on the Galactic mass distribution

Huang

Liu

Yuan

et al. 2016

Mon. Not. R. Astron. Soc.

158

179

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“…2 e.g., the HK (Beers et al 1985(Beers et al , 1992, Hamburg/ESO (Christlieb 2003), SEGUE (Yanny et al 2009), and LAMOST survey (Cui et al 2012;Deng et al 2012). …”

Section: Introductionmentioning

confidence: 99%

Classification of extremely metal-poor stars: absent region in A(C)–[Fe/H] plane and the role of dust cooling

Chiaki

Tominaga

Nozawa

2017

Monthly Notices of the Royal Astronomical Society: Letters

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Extremely metal-poor (EMP) stars are the living fossils with records of chemical enrichment history at the early epoch of galaxy formation. By the recent large observation campaigns, statistical samples of EMP stars have been obtained. This motivates us to reconsider their classification and formation conditions. From the observed lower-limits of carbon and iron abundances of A cr (C) ∼ 6 and [Fe/H] cr ∼ −5 for C-enhanced EMP (CE-EMP) and C-normal EMP (CN-EMP) stars, we confirm that gas cooling by dust thermal emission is indispensable for the fragmentation of their parent clouds to form such low-mass, i.e., long-lived stars, and that the dominant grain species are carbon and silicate, respectively. We constrain the grain radius r cool

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“…The recently completed RAdial Velocity Experiment (RAVE) survey (Steinmetz et al 2006) has also provided atmospheric parameters, radial velocities and chemical abundances for six individual elements for more than 400 000 stars (Kordopatis et al 2013). Ongoing spectroscopic surveys, such as the Gaia-ESO Survey (GES; Gilmore 2012), Galactic Archaeology with HERMES survey (GALAH; Zucker et al 2012), or LAMOST Experiment for Galactic Understanding and Exploration (LEGUE; Deng et al 2012), are continuously increasing the number of stars with available spectroscopic information. In fact, these large spectrophotometric data sets will, when analysed together, enable a description of the structure and substructures of the Galaxy with unprecedented detail, excellent statistics, and full use of the 6D phase-space information.…”

Section: Introductionmentioning

confidence: 99%

Spectro-photometric distances to stars: A general purpose Bayesian approach

Santiago

Brauer

Anders

et al. 2015

A&A

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107

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Context. Determining distances to individual field stars is a necessary step towards mapping Galactic structure and determining spatial variations in the chemo-dynamical properties of stellar populations in the Milky Way. Aims. In order to provide stellar distance estimates for various spectroscopic surveys, we have developed a code that estimates distances to stars using measured spectroscopic and photometric quantities. We employ a Bayesian approach to build the probability distribution function over stellar evolutionary models given these data, delivering estimates of model parameters (including distances) for each star individually. Our method provides several alternative distance estimates for each star in the output, along with their associated uncertainties. This facilitates the use of our method even in the absence of some measurements. Methods. The code was first tested on simulations, successfully recovering input distances to mock stars with 1% bias. We found the uncertainties scale with the uncertainties in the adopted spectro-photometric parameters. The method-intrinsic random distance uncertainties for typical spectroscopic survey measurements amount to around 10% for dwarf stars and 20% for giants, and are most sensitive to the quality of log g measurements. Results. The code was then validated by comparing our distance estimates to parallax measurements from the H mission for nearby stars (<300 pc), to asteroseismic distances of CoRoT red giant stars, and to known distances of well-studied open and globular clusters. The photometric data of these reference samples cover both optical and infrared wavelengths. The spectroscopic parameters are also based on spectra taken at various wavelengths, with varying spectral coverage and resolution: the Sloan Digital Sky Survey programs SEGUE and APOGEE, as well as various ESO instruments. Conclusions. External comparisons confirm that our distances are subject to very small systematic biases with respect to the fundamental H scale (+0.4% for dwarfs, and +1.6% for giants). The typical random distance scatter is 18% for dwarfs, and 26% for giants. For the CoRoT-APOGEE sample, which spans Galactocentric distances of 4−14 kpc, the typical random distance scatter is 15% both for the nearby and farther data. Our distances are systematically larger than the CoRoT distances by about +9%, which can mostly be attributed to the different choice of priors. The comparison to known distances of star clusters from SEGUE and APOGEE has led to significant systematic differences for many cluster stars, but with opposite signs and substantial scatter. Finally, we tested our distances against those previously determined for a high-quality sample of giant stars from the RAVE survey, again finding a small systematic trend of +5% and an rms scatter of 30%. Efforts are underway to provide our code to the community by running it on a public server.

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LAMOST Experiment for Galactic Understanding and Exploration (LEGUE) — The survey's science plan

Cited by 541 publications

References 143 publications

The Milky Way's rotation curve out to 100 kpc and its constraint on the Galactic mass distribution

The Milky Way's rotation curve out to 100 kpc and its constraint on the Galactic mass distribution

Classification of extremely metal-poor stars: absent region in A(C)–[Fe/H] plane and the role of dust cooling

Spectro-photometric distances to stars: A general purpose Bayesian approach

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