Jingkun Zhao

A Catalog of Moving Group Candidates in the Solar Neighborhood

Based on the kernel estimator and wavelet technique, we have identified 22 moving group candidates in the solar neighborhood from a sample which includes around 14,000 dwarfs and 6000 giants. Six of them were previously known as the Hercules stream, the Sirus-UMa stream, the Hyades stream, the Caster group, the Pleiades stream, and the IC 2391; five of them have also been reported by other authors. 11 moving group candidates, not previously reported in the literature, show prominent structures in dwarf or giant samples. A catalog of moving group candidates in the solar neighborhood is presented in this work.

THE CHROMOSPHERIC ACTIVITY, AGE, METALLICITY, AND SPACE MOTIONS OF 36 WIDE BINARIES

We present the chromospheric activity (CA) levels, metallicities, and full space motions for 41 F, G, K, and M dwarf stars in 36 wide binary systems. Thirty-one of the binaries contain a white dwarf (WD) component. In such binaries, the total age can be estimated by adding the cooling age of the WD to an estimate of the progenitor’s main-sequence lifetime. To better understand how CA correlates to stellar age, 14 cluster member stars were also observed. Our observations demonstrate for the first time that, in general, CA decays with age from 50 Myr to at least 8 Gyr for stars with 1.0 V − I 2.4. However, little change occurs in the CA level for stars with V − I < 1.0 between 1 Gyr and 5 Gyr, consistent with the results of Pace et al. Our sample also exhibits a negative correlation between the stellar age and metallicity, a positive correlation between the stellar age and W space velocity component, and the W velocity dispersion increases with age. Finally, the population membership of these wide binaries is examined based upon their U, V, W kinematics, metallicity, and CA. We conclude that wide binaries are similar to field and cluster stars in these respects. More importantly, they span a much more continuous range in age and metallicity than is afforded by nearby clusters.

LAMOST Spectroscopic Survey of the Galactic Anticentre (LSS-GAC): the second release of value-added catalogues

We present the second release of value-added catalogues of the LAMOST Spectroscopic Survey of the Galactic Anticentre (LSS-GAC DR2). The catalogues present values of radial velocity

M DWARF CATALOG OF THE LAMOST PILOT SURVEY

V_{\rm r}

70 DA WHITE DWARFS IDENTIFIED IN LAMOST PILOT SURVEY

, atmospheric parameters --- effective temperature

White-dwarf-Main-sequence Binaries Identified from the LAMOST Pilot Survey

T_{\rm eff}

Stellar activity with LAMOST – I. Spot configuration in Pleiades

, surface gravity log

Stellar Stream Candidates in the Solar Neighborhood Found in the LAMOST DR3 and TGAS

g

Abundance Pattern of Metal-Rich Stars from 14 Old and 24 Young Stars

, metallicity [Fe/H],

SERENDIPITOUS DISCOVERY OF A CANDIDATE DEBRIS DISK AROUND THE DA WHITE DWARF SDSS J114404.74+052951.6

\alpha