The LAMOST spectroscopic survey of stars in the Kepler field of view: Activity indicators and stellar parameters (original) (raw)
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The Kepler field of view covered with the LAMOST spectroscopic observations
Proceedings of the International Astronomical Union
The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) at the Xinglong observatory in China is a 4-m telescope equipped with 4,000 optical fibres. In 2010, we initiated the LAMOST-Kepler project which aimed at collecting low-resolution spectra of stars from the Kepler Input Catalog covering uniformly the Kepler field of view. The first round of the LAMOST-Kepler project has been completed in September 2014 resulting in more than 100,000 low-resolution spectra. We used those data to derive the effective temperature, the surface gravity, and the mean metallicity of our targets, as well as to detect fast rotators, and to identify emission-line stars. Our results are consistent with those reported in the literature and derived from high-resolution spectroscopy. The second round of the LAMOST-Kepler project will allow to improve the coverage of the Kepler field and to repeat observations of selected targets.
Overview of the LAMOST-Kepler project
Research in Astronomy and Astrophysics, 2020
The NASA Kepler mission obtained long-term high-quality photometric observations for a large number of stars in its original field of view from 2009 to 2013. To provide reliable stellar parameters in a homogeneous way, the LAMOST telescope began to carry out low-resolution spectroscopic observations for as many stars as possible in the Kepler field in 2012. By June 2018, 238 386 low-resolution spectra with SNR g ≥ 6 had been collected for 155 623 stars in the Kepler field, enabling the determination of atmospheric parameters and radial velocities, as well as spectral classification of the target stars. This information has been used by astronomers to carry out research in various fields, including stellar pulsations and asteroseismology, exoplanets, stellar magnetic activity and flares, peculiar stars and the Milky Way, binary stars, etc. We summarize the research progress in these fields where the usage of data from the LAMOST-Kepler (LK) project has played a role. In addition, tim...
LAMOST observations in the Kepler field
Proceedings of the International Astronomical Union, 2013
The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (lamost) at the Xinglong observatory in China is a new 4-m telescope equipped with 4,000 optical fibers. In 2010, we initiated the lamost-Kepler project. We requested to observe the full field-of-view of the nominal Kepler mission with the lamost to collect low-resolution spectra for as many objects from the KIC 10 catalogue as possible. So far, 12 of the 14 requested lamost fields have been observed resulting in more than 68,000 low-resolution spectra. Our preliminary results show that the stellar parameters derived from the lamost spectra are in good agreement with those found in the literature based on high-resolution spectroscopy. The lamost data allows to distinguish dwarfs from giants and can provide the projected rotational velocity for very fast rotators.
The Astrophysical Journal Supplement Series, 2018
The LAMOST-Kepler (LK-) project was initiated to use the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) to make spectroscopic follow-up observations for the targets in the field of the Kepler mission. The Kepler field is divided into 14 subfields that are adapted to the LAMOST circular field with a diameter of 5 degrees. During the regular survey phase of LAMOST, the LK-project took data from 2012 June to 2017 June and covered all the 14 subfields at least twice. In particular, we describe in this paper the second Data Release of the LK-project, including all spectra acquired through 2015 May to 2017 June together with the first round observations of the LK-project from 2012 June to 2014 September. The LK-project now counts 227 870 spectra of 156 390 stars, among which we have derived atmospheric parameters (log g, T eff and [Fe/H]) and heliocentric radial velocity (RV) for 173 971 spectra of 126 172 stars. These parameters were obtained with the most recent version of the LAMOST Stellar Parameter Pipeline v 2.9.7. Nearly one half, namely 76 283 targets, are observed both by LAMOST and Kepler telescopes. These spectra, establishing a large spectroscopy library, will be useful for the entire astronomical community, particularly for planetary science and stellar variability on Kepler targets.
The Astrophysical Journal Supplement Series, 2020
Phase II of the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST)-Kepler/K2 survey (LK–MRS), initiated in 2018, aims at collecting medium-resolution spectra (R ∼ 7500; hereafter MRS) for more than 50,000 stars with multiple visits (∼60 epochs) over a period of 5 yr (2018 September to 2023 June). We selected 20 footprints distributed across the Kepler field and six K2 campaigns, with each plate containing a number of stars ranging from ∼2000 to ∼3000. During the first year of observations, the LK–MRS has already visited 13 plates 223 times over 40 individual nights, and collected ∼280,000 and ∼369,000 high-quality spectra in the blue and red wavelength ranges, respectively. The atmospheric parameters and radial velocities for ∼259,000 spectra of 21,053 targets were successfully calculated by the LAMOST stellar parameter pipeline. The internal uncertainties for the effective temperature, surface gravity, metallicity, and radial velocity are found to be 100 K, 0.15 dex...
Research in Astronomy and Astrophysics, 2019
Radial velocity is one of the key measurements in understanding the fundamental properties of stars, stellar clusters and the Galaxy. A plate of stars in the Kepler field was observed in May of 2018 with the medium-resolution spectrographs of LAMOST, aiming to test the performance of this new system which is the upgraded equipment of LAMOST after the first five-year regular survey. We present our analysis on the radial velocity measurements (RVs) derived from these data. The results show that slight and significant systematic errors exist among the RVs obtained from the spectra collected by different spectrographs and exposures, respectively. After correcting the systematic errors with different techniques, the precision of RVs reaches ∼1.3, ∼1.0, ∼0.5 and ∼0.3 km s−1 at S/N r = 10, 20, 50 and 100, respectively. Comparing with the RVs of standard stars from the APOGEE survey, our RVs are calibrated with a zero-point shift of ∼7 km s−1. The results indicate that the LAMOST medium-res...
New Astronomy, 2018
The LAMOST spectral survey provides a rich databases for studying stellar spectroscopic properties and chromospheric activity. We cross-matched a total of 105,287 periodic variable stars from several photometric surveys and databases (CSS, LINEAR, Kepler, a recently updated eclipsing star catalogue, ASAS, NSVS, some part of SuperWASP survey, variable stars from the Tsinghua University-NAOC Transient Survey, and other objects from some new references) with four million stellar spectra published in the LAMOST data release 2 (DR2). We found 15,955 spectra for 11,469 stars (including 5398 eclipsing binaries). We calculated their equivalent widths (EWs) of their H α , H β , H γ , H δ and Ca ii H lines. Using the H α line EW, we found 447 spectra with emission above continuum for a total of 316 stars (178 eclipsing binaries). We identified 86 active stars (including 44 eclipsing binaries) with repeated LAMOST spectra. A total of 68 stars (including 34 eclipsing binaries) show chromospheric activity variability. We also found LAMOST spectra of 12 cataclysmic variables, five of which show chromospheric activity variability. We also made photometric follow-up studies of three short period targets (DY CVn, HAT-192-0001481, and LAMOST J164933.24+141255.0) using the Xinglong 60-cm telescope and the SARA 90-cm and 1-m telescopes, and obtained new BVRI CCD light curves. We analyzed these light curves and obtained orbital and starspot parameters. We detected the first flare event with a huge brightness increase of more than about 1.5 magnitudes in R filter in LAMOST J164933.24+141255.0.
Rotational Velocities of Am and Non-chemical-peculiar Stars Based on Kepler and LAMOST DR5
The Astronomical Journal
Rotation is a critical physical process operating in the formation of Am stars. There is a strong correlation between low-velocity rotation and chemical peculiarity. However, the existence of many non-chemical-peculiar slow rotators challenges the understanding of Am stars. The purpose of our work is to search for low-velocity rotating non-chemical-peculiar A-type stars and Am stars and to make a comparative analysis. In this paper, we pick out a sample from the LAMOST-Kepler project, including 21 Am stars, 125 non-chemical-peculiar slow rotators, and 53 non-chemical-peculiar fast rotators. We calculate the rotational frequencies through a periodic change of light curves caused by inhomogeneous stellar surfaces and then obtain the rotational velocities. For slow rotators, the age of Am stars is statistically younger than that of non-chemical-peculiar stars in the same temperature bin. In the comparison of the period, the average amplitude, and stellar mass of Am and non-chemical-peculiar stars, we discover that there is no difference in the photometric variability between Am and nonchemical-peculiar stars, which implies similar inhomogeneities on the surfaces. The average amplitude of non-chemical-peculiar stars has a downward trend with the increase of effective temperature and stellar mass, which is consistent with the theoretical prediction caused by weak dynamo-generated magnetic fields in A-type stars. In addition, we confirm four nonchemical-peculiar stars that have flares by checking field-of-view images, pixel images, and pixel-level light curves.
The LAMOST stellar parameter pipeline at Peking University - LSP3
Monthly Notices of the Royal Astronomical Society
We introduce the LAMOST Stellar Parameter Pipeline at Peking University --- LSP3, developed and implemented for the determinations of radial velocity VrmrV_{\rm r}Vrmr and stellar atmospheric parameters (effective temperature TrmeffT_{\rm eff}Trmeff, surface gravity log\,$g$, metallicity [Fe/H]) for the LAMOST Spectroscopic Survey of the Galactic Anti-center (LSS-GAC). We describe the algorithms of LSP3 and examine the accuracy of parameters yielded by it. The precision and accuracy of parameters yielded are investigated by comparing results of multi-epoch observations and of candidate members of open and globular clusters, with photometric calibration, as well as with independent determinations available from a number of external databases, including the PASTEL archive, the APOGEE, SDSS and RAVE surveys, as well as those released in the LAMOST DR1. The uncertainties of LSP3 parameters are characterized and quantified as a function of the spectral signal-to-noise ratio (SNR) and stellar atmospheric...