Self-consistent Stellar Radial Velocities from LAMOST Medium-resolution Survey DR7

Zhang, Bo; Li, Jiao; Yang, Fan; Xiong, Jian-Ping; Fu, Jian-Ning; Liu, Chao; Tian, Hao; Li, Yin-Bi; Wang, Jiaxin; Liang, Caixia; Zhou, Yawen; Zong, Weikai; Yang, Chengqun; Liu, Nian; Hou, Yonghui

doi:10.3847/1538-4365/ac0834

Cited by 54 publications

(68 citation statements)

References 54 publications

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“…Before applying the SLAM to the observational data, we first need to bring the LAM-OST spectra into the rest frame such that they are in agreement with those of the TLUSTY model spectra. We achieved this goal by collecting the Radial Velocity (RV) measurements of our sample stars appearing in the work of Zhang et al (2021), who performed the RV measurements for all stars in the LAMOST DR7 through a cross-correlation algorithm. We then corrected the RV variations in our observed spectra.…”

Section: Results and Validationmentioning

confidence: 99%

The Early-type Stars from LAMOST survey: Atmospheric parameters

Guo,

Zhang,

Liu

et al. 2021

Preprint

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Massive stars play key roles in many astrophysical processes. Deriving atmospheric parameters of massive stars is important to understand their physical properties and thus are key inputs to trace their evolution. Here we report our work on adopting the data-driven technique Stellar LAbel Machine (SLAM) with the non-LTE TLUSTY synthetic spectra as the training dataset to estimate the stellar parameters of LAMOST optical spectra for early-type stars. We apply two consistency tests to verify this machine learning method and compare stellar labels given by SLAM with that in literature for several objects having high-resolution spectra. We provide the stellar labels of effective temperature (T eff ), surface gravity (log g), metallicity ([M/H]), and projected rotational velocity (v sin i) for 3,931 and 578 early-type stars from LAMOST Low-Resolution Survey (LAMOST-LRS) and Medium-Resolution Survey (LAMOST-MRS), respectively. To estimate the average statistical uncertainties of our results, we calculated the standard deviation between the predicted stellar label and the pre-labeled published values from the high-resolution spectra. The uncertainties of the four parameters are σ(T eff ) = 2, 185K, σ(log g) = 0.29 dex, and σ(v sin i) = 11 km s −1 for MRS, and σ(T eff ) = 1, 642K, σ(log g) = 0.25 dex, and σ(v sin i) = 42 km s −1 for LRS spectra, respectively. We notice that parameters of T eff , log g and [M/H] can be better constrained using LRS spectra rather than using MRS spectra, most likely due to their broad wavelength coverage, while v sin i is constrained better by MRS spectra than by LRS spectra, probably due to the relatively accurate line profiles of MRS spectra.

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Section: Results and Validationmentioning

confidence: 99%

The Early-type Stars from LAMOST survey: Atmospheric parameters

Guo,

Zhang,

Liu

et al. 2021

Preprint

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“…The radial velocities (RVs) are extracted from MRS with the cross-correlation method (Zhang et al 2021). Since the RVs have different systematic errors at different observational time (Liu et al 2019;Zong et al 2020), the constant radial velocity stars in the same spectrograph are used to correct the systematic variations (Zhang et al 2021). We note that KIC 6859813 and KIC 8097825 are double-lined spectroscopic binaries (SB2) and KIC 5527172 is a single-lined spectroscopic binary (SB1).…”

Section: Lamost Spectramentioning

confidence: 99%

The Properties and Evolutions of Starspots on Three Detached Eclipsing Binaries in the LAMOST-Kepler survey

Wang,

Fu,

Zong

et al. 2022

Preprint

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The spotted detached eclipsing binary (DEB) offers insights into starspots on the binary. Three spotted DEBs, KIC 8097825, KIC 6859813, and KIC 5527172, which were observed by the 𝐾𝑒 𝑝𝑙𝑒𝑟 photometry and LAMOST spectroscopy, are studied in this work. The physical parameters of binaries are determined by binary modeling. The sizes, lifetimes, and single/double-dip ratio (SDR) of starspots are derived by starspot analysis. KIC 8097825 has large starspots. KIC 6859813 has a spot rotation period shorter than its orbital period but the system should be synchronized inferred from timescale estimation. The difference may be the result of the surface differential rotation. The KIC 5527172 has a long spot lifetime and an M dwarf component with an inflation radius. The primaries of these binaries and the secondary of KIC 8097825 have spots. Adding spotted DEBs of literature, we compare the starspots on binaries with those on the single stars. The spot sizes of starspots on 65% binaries are smaller than the median of those on single stars. The lifetimes of starspots on binaries are consistent with those on single stars when the rotation periods are larger than 3 days. SDRs for half of the binaries are consistent with those of single star systems, while another half are smaller. The relative lifetime positively correlates with the RMS and SDR but negatively correlates with the rotation period. These relations are similar to those of spots on the single star systems. Binaries with luminosity ratios close to the unit tend to have more double dips.

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“…The spectra were reduced and the wavelength calibration was performed following the standard LAMOST 2D pipeline (Luo et al 2015;Ren et al 2021). Because cosmic rays were not fully removed by the pipeline, we adopted the Python package lapsec 2 from Zhang et al (2021) to remove any residual cosmic ray features present in the spectra. In order to rectify the observed spectra, we then transformed the spectra of the individual stars onto a uniform wavelength grid and rectified the spectra through a spline fitting to the selected pseudo continuum regions.…”

Section: Lamost Mrs Optical Spectroscopymentioning

confidence: 99%

Identification of new classical Be stars from the LAMOST MRS survey

Wang,

Li,

et al. 2022

Preprint

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Be stars are B-type main-sequence stars that display broad Balmer emission lines in their spectra. Identification of Be population is essential to further exam the formation and evolutionary models. We report the detection of classical Be (CBe) stars from observations with the Large sky Area Multi-Object fiber Spectroscopic Telescope Medium Resolution Survey of Date Release 7 (LAMOST MRS DR7). We used a deep convolutional neural network, the ResNet with an 18-layer module to examine the morphology of the Hα profile. We identified 1,162 candidate Be stars from the collection of 2,260,387 spectra for 789,918 stars in the database. The ResNet network achieves a Be star classification accuracy of 99.5%. Among the detections, 151 of these are prior known Be stars cross-matched from the literature. By applying a three-step test, we identified 183 new CBe stars. We find that 41 CBe stars are members of known open clusters. Based upon an investigation of the kinematics of the identified CBe stars from the Gaia EDR3 astrometric solutions, we identified 16 new runaways. These new identifications will provide as a reference for future follow-ups to further investigate their physical properties.

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Self-consistent Stellar Radial Velocities from LAMOST Medium-resolution Survey DR7

Cited by 54 publications

References 54 publications

The Early-type Stars from LAMOST survey: Atmospheric parameters

The Early-type Stars from LAMOST survey: Atmospheric parameters

The Properties and Evolutions of Starspots on Three Detached Eclipsing Binaries in the LAMOST-Kepler survey

Identification of new classical Be stars from the LAMOST MRS survey

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