Planets Across Space and Time (PAST). VIII : Kinematic Characterization and Identification of Radial Velocity Variables for the LAMOST-Gaia-TESS Stars

Abstract

The Transiting Exoplanet Survey Satellite (TESS) has discovered over 6700 nearby exoplanets candidates using the transit method through its all-sky survey. Characterizing the kinematic properties and identifying variable stars for the TESS stellar sample is crucial for revealing the correlations between the properties of planetary systems and the properties of stars (e.g., Galactic components, age, chemistry, dynamics, radiation). Based on data from TESS, Gaia DR3, and LAMOST DR10, we present a catalog of kinematic properties (i.e., Galactic positions, velocities, orbits, Galactic components, and kinematic age) as well as other basic stellar parameters for $\sim 660,000$ TESS stars. Our analysis of the kinematic catalog reveals that stars belonging to different Galactic components (i.e., thin disk, thick disk, halo and 12 streams in the disk) display distinctive kinematic and chemical properties. We also find that hot planets with period less then 10 days in the TESS sample favor thin disk stars compared to thick disk stars, consistent with previous studies. Furthermore, using the LAMOST multiple-epoch observations, we identify 41,445 stars exhibiting significant radial velocity variations, among which 7,846 are classified as binary stars. By fitting the radial velocity curves, we further derive orbital parameters (e.g., mass ratio, orbital period and eccentricity) for 297 binaries. The observed decreasing orbital eccentricity with shorting period reveals evidence of tidal circularization. The catalogs constructed in this work have laid a solid foundation for future work on the formation and evolution of stellar and planetary systems in different Galactic environments.

Figures (19)

• Figure 1: Radial velocity and stellar parameters obtained from Gaia RVS (left panel) and LAMOST (right panel) in comparison with APOGEE. Dark red fitted regression lines illustrate the correlations between the respective datasets, with slope and intercept values indicated. The line $y = x$ is plotted as a red dashed line for reference.
• Figure 2: Top panel: Galactocentric radius (R) vs. height (Z) for the LAMOST_MRS-Gaia-TESS sample. A yellow star marks the location of the Sun (8.18 kpc, 0.027 kpc). Bottom panel: Galactocentric radius (R) vs. angle ($\theta$) for the MRS sample, with (8.18 kpc, $0^{\circ}$) marking the position of Sun. Red points represent the TOI host stars.
• Figure 3: The Toomre diagram of LAMOST_MRS-Gaia-TESS stars for different Galactic components (top panel) and stellar streams (bottom panel). Different color represents different memberships. Dotted lines indicate constant values of the total Galactic velocity $V_{tot}$ in stpdf of 25 $\rm km\ s^{-1}$ and 50 $\rm km\ s^{-1}$.
• Figure 4: The distribution of disk stars in the vertical angular momentum $L_z$ vs. radial action $\sqrt{J_\text{R}}$ plane for the LAMOST_MRS-Gaia-TESS sample, with the thin disk ($N=172,435$), thick disk ($N=6,361$) and halo ($N=101$) populations shown in blue, red, and black, respectively. Contour density maps illustrate the stellar distributions, with darker regions indicating higher star densities, the peak density location for each component is marked with a yellow star. Colorbars for each component are scaled separately since their sample sizes differ significantly, the ticks show an estimated number of sample in each grid. As shown, different components occupy distinct regions in the $L_z$-$J_R$ plane, reflecting their kinematic differences.
• Figure 5: Same as Figure \ref{['fig: Lz disks MRS']} but for the distribution in the $[\alpha/\text{Fe}]$ vs. $[\text{Fe}/\text{H}]$ plane for the LAMOST_MRS-Gaia-TESS sample. The red dashed line represents the division between the thick and thin disks from leeFORMATIONEVOLUTIONDISK2011, the distribution reveals distinct chemical abundance trends among these populations.