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We have cross-matched the LAMOST DR3 with the Gaia DR1 TGAS catalogs and obtained a sample of 166,827 stars with reliable kinematics. A technique based on the wavelet transform was applied to detect significant overdensities in velocity space among five subsamples divided by spatial position. In total, 16 significant overdensities of stars with very similar kinematics were identified. Among these, four are new stream candidates and the rest are previously known groups. Both the U-V velocity and metallicity distributions of the local sample show a clear gap between the Hercules structure and the Hyades-Pleiades structure. The U-V positions of these peaks shift with the spatial position. Following a description of our analysis, we speculate on possible origins of our stream candidates.

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Super metal-rich stars with [Fe/H] > 0.4 are selected from LAMOST DR6, and two groups, the blue and the red, are found in the T eff versus logg diagram with a temperature gap between them. In combination with Gaia DR2, stellar positions, velocities, and orbits are calculated, and spatial distributions, kinematical properties, and orbital parameters are compared between the two groups. The blue group shows mainly thin-disk kinematics and spans a wide R range of 6–12 kpc, while the red group has both the thin-disk and the thick-disk kinematics with a narrower range of R = 6–10 kpc. The kinematical and orbital parameters of stars in the blue group indicate that they could belong to the young population with age less than 1 Gyr, rather than blue stragglers of the old population. The orbital parameters, R p , R a , and R g , of the red group with the thick-disk kinematics are smaller than those with the thin-disk kinematics. The distributions of birth radius and migration distance indicate that radial migration is a favorable origin for the red group, especially those with the thick-disk kinematics, but not for the blue group. The relative magnitude of radial migration is of 51% for the whole sample and of 64% for the red group only. The corotation radial migration caused by the bars and spiral arms at resonances is the most likely mechanism for explaining these properties of SMR stars in this work.

W e consider the quantization of LC (inductance-capacitance) circuit at a finite temperature T as any practical circuits always produce Joule heat except for superconductivity. It is shown that the quantum mechanical zeropoint fluctuations o f both charge and current increase with upgoing T . Thermal field dynamics is used in our discussion.

We identify member stars of more than 90 open clusters in the LAMOST survey. With the method of Fang et al. (2018), the chromospheric activity (CA) indices log R CaK for 1091 member stars in 82 open clusters and log R Hα for 1118 member stars in 83 open clusters are calculated. The relations between the average log R CaK , log R Hα in each open cluster and its age are investigated in different T eff and [Fe/H] ranges.We find that CA starts to decrease slowly from log t = 6.70 to log t = 8.50, and then decreases rapidly until log t = 9.53. The trend becomes clearer for cooler stars. The quadratic functions between log R and log t with 4000K < T eff < 5500K are constructed, which can be used to roughly estimate ages of field stars with accuracy about 40% for log R CaK and 60% for log R Hα .

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