A5071418187- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Geophysics and Gravity Measurements
- Scientific Research and Discoveries
- Pulsars and Gravitational Waves Research
- Cold Atom Physics and Bose-Einstein Condensates
- Astrophysics and Cosmic Phenomena
- Spectroscopy and Laser Applications
- Phase Equilibria and Thermodynamics
- High-pressure geophysics and materials
- Geophysics and Sensor Technology
- Nonlinear Waves and Solitons
- Solar and Space Plasma Dynamics
- Dark Matter and Cosmic Phenomena
- Nonlinear Dynamics and Pattern Formation
- Geomagnetism and Paleomagnetism Studies
- Space Satellite Systems and Control
- Numerical methods for differential equations
- Adaptive optics and wavefront sensing
Southern Federal University
2016-2025
Institute of Physics
2002-2021
Yale University
2003-2016
Isaac Newton Institute
2003-2016
National Astronomical Observatory of Japan
1997-2001
Since the science white paper of Large High Altitude Air Shower Observatory (LHAASO) published on arXiv in 2019 [e-Print: 1905.02773 (astro-ph.HE)], LHAASO has completed transition from a project to an operational gamma-ray astronomical observatory is new generation multi-component facility located Daocheng, Sichuan province China, at altitude 4410 meters. It aims measuring with unprecedented sensitivity spectrum, composition, and anisotropy cosmic rays energy range between 10$^{12}$...
We analyze the three-dimensional kinematics of a sample ∼4400 red clump stars ranging between 5 and 10 kpc from Galactic center up to 3 plane. This is representative for metal-rich ([Fe/H] = −0.6 − +0.5) thick disk. Absolute proper motions are fourth release Southern Proper Motion Program radial velocities second Radial Velocity Experiment. The derived kinematical properties disk include rotational velocity gradient ∂Vθ/∂z −25.2 ± 2.1 km s−1 kpc−1, dispersions s−1, velocity-ellipsoid tilt...
Absolute proper motions are determined for stars and galaxies to V = 17.5 over a 450 deg2 area that encloses both Magellanic Clouds. The based on photographic CCD observations of the Yale/San Juan Southern Proper Motion program, which span baseline 40 years. Multiple, local relative proper-motion measures combined in an overlap solution using photometrically selected Galactic disk define global system is then transformed absolute external Hipparcos tie into ICRS. resulting catalog 1.4...
We present a detailed analysis of kinematics the Milky Way disk in solar neighborhood using GAIA DR3 catalog. To determine local stellar disks galaxy we use complete sample 278,228 red giant branch (RGB) stars distributed cylinder, centered at Sun with 1 kpc radius and half-height 0.5 kpc. separately kinematical properties RGB for each Galactic hemisphere search possible asymmetries. The reveal existence two kinematically distinct components: thin mean velocities ${V_R}, {V_{\phi}}, {V_Z}$...
Using the RR Lyrae surveys Gaia DR3 Specific Objects Study, PanSTARRS1 and ASAS-SN-II, we determine Milky Way’s thick disc scale length height as well radial of galaxy’s inner halo. We use a Bayesian approach to estimate these values using two independent techniques: Markov chain Monte Carlo sampling, importance nested sampling. consider vertical density profiles for disc. In exponential model, is hR=2.14−0.17+0.19 kpc, its hz=0.64−0.06+0.06 kpc. squared hyperbolic secant profile sech2,...
This paper examines a second-order nonlinear mechanism that appears to bear responsibility for (1) eliciting transport of mass and angular momentum in self-gravitating gaseous disks (2) inducing mode saturation can preclude the onset disk fragmentation. Our analysis indicates quantitative detail how torques arising from gravitationally unstable spiral modes lead accretion. We begin by performing linear global stability on an idealized model equilibrium is prone single , rapidly growing...
This paper seeks to develop a fuller understanding of the behavior thin, polytropic, self-gravitating disks. Our approach consists performing detailed analysis representative model disk that is known be susceptible single, rapidly growing, two-armed spiral mode. Numerical simulations evolution this are presented; these new have both an improved radial dynamic range and more realistic boundary conditions. numerical work indicates primary unstable mode robustly endemic itself not pathological...
(abridged) We have measured the absolute proper motions of nine low-latitude, inner Galaxy globular clusters, namely NGC 6273 (M 19), 6284, 6287, 6293, 6333 9), 6342, 6356, 6388 and 6441. These are first determinations ever made for these clusters. The on ICRS via Hipparcos. proper-motion errors range between 0.4 0.9 mas/yr, dominated by number measurable cluster members in regions which very crowded bulge/bar thick disk. This samle contains five metal poor ([Fe/H < -1.0) four rich clusters;...
Strongly interacting galaxies undergo a short-lived but dramatic phase of evolution characterized by enhanced star formation, tidal tails, bridges and other morphological peculiarities. The nearest example pair is the Magellanic Clouds, whose dynamical interaction produced gaseous features known as Stream trailing pair's orbit about Galaxy, Bridge between Leading Arm, wide irregular feature leading orbit. Young, newly formed stars in are to exist, giving witness recent Clouds. However,...
We have reestimated the surface density of Galactic disk in solar neighborhood within ±0.4 kpc Sun using parallaxes and proper motions a kinematically spatially unbiased sample 1476 old bright red giant stars from Hipparcos catalog with measured radial velocities Barbier-Brossat & Figon. determine vertical distribution giants as well velocity dispersion (14.4 ± 0.3 km s-1) combine these to derive gravitating matter function coordinate z. The increases 10.5 0.5 M⊙ pc-2 ±50 pc 42 6 ±350 pc....
The kinematical properties of the Galactic Thick Disk are studied using absolute proper motions from SPM3 Catalog and 2MASS near-infrared photometry for a sample ~1200 red giants in direction South Pole. photometrically-selected is dominated by stars, as indicated number-density distribution that varies with distance plane single-valued exponential over range 1
We make use of recent estimates for the parameters Milky Way’s halo globular clusters and study influence galactic bar on dynamics these by computing their orbits. both an axisymmetric non-axisymmetric potentials, which include rotating elongated bar/bulge structure. account observational errors in positions velocities explore clusters’ evolution. This is contained angular momentum–total energy plane, (Lz,E), widely exploited as indicator groups that originated from same accretion event....
Using a complete sample of about 330,000 dwarf stars, well measured by Gaia DR3, limited to the galactic north and south solid angles |b|<75° up vertical distance 2 kpc, we analyze structure Milky Way stellar disks, based on projected tangential velocities. From selected subsamples dominated their corresponding population, obtain thin thick disk scale heights as hZ=279.76±12.49 pc HZ=797.23±12.34 pc, respectively. Then from simultaneous fitting sum two populations over whole sample,...
We explore an accretion origin for ω Cen by N-body modeling of the orbital decay and disruption a Milky Way dwarf satellite. This work is focused on studying particular satellite model that aims to reproduce present orbit Cen, as recently determined from absolute proper motions. The launched 58 kpc Galactic center, radial low-inclination orbit. find capture scenario can produce Cen-like object with current low-energy cluster. Our best nucleated galaxy Hernquist density profile has mass 8 ×...
A proper-motion study of a field 20' × inside Plaut's low-extinction window (l,b) = (0°, - 8°) has been completed. Relative proper motions and photographic BV photometry have derived for ∼21,000 stars reaching to V ∼ 20.5 mag, based on the astrometric reduction 43 plates, spanning over 21 yr epoch difference. Proper-motion errors are typically 1 mas yr-1, field-dependent systematics below 0.2 yr-1. Cross-referencing with 2MASS catalog yielded sample ∼8700 stars, from which predominantly disk...
We employ Gaia DR2 proper motions for 151 Milky Way globular clusters from Vasiliev (2019) in tandem with distances and line-of-sight velocities to derive their kinematical properties. To assign the thick disk, bulge, halo we follow approach of Posti et al. (2018) who distinguished among different Galactic stellar components using stars's orbits. In particular, use ratio $L_{z}/e$, $Z$ projection angular momentum eccentricity, as population tracer, which complement chemical abundances...
We perform N-body simulations of the dynamical evolution a dwarf galaxy falling into Milky Way in order to understand formation scenario peculiar globular cluster ω Centauri. use self-consistent models bulge and disc Way, as well galaxy, explore range with different density distributions. Namely, we King Hernquist profiles model distribution dwarf. The central region our has profile approximately ∝r−2, while that is ∝r−1. difference dwarf's distributions leads distinct evolutionary...
Using observational data, we build numerical N-body, hydrodynamical and combined equilibrium models for the spiral galaxy NGC 5247. The turn out to be unstable towards structure formation. We simulate scenarios of formation different sets rotation curves, radial velocity dispersion profiles disk thickness demonstrate that in all cases a simulated pattern qualitatively agrees with observed morphology also an admixture gaseous component mass about few percent total increases lifetime by...
Despite their close proximity, the complex interplay between two Magellanic Clouds, Milky Way, and resulting tidal features, is still poorly understood. Recent studies have shown that Large Cloud (LMC) has a very extended disk strikingly perturbed in its outskirts. We search for recent star formation far outskirts of LMC, out to ~30 degrees from center. collected intermediate-resolution spectra thirty-one young candidates periphery LMC measured radial velocity, stellar parameters, distance...
We present N-body simulations of unstable spiral modes in a dynamically cool collisionless disc. show that grow thin disk accordance with the analytical perturbation theory. use particle-mesh code superbox nested grids to follow evolution spirals emerge from an equilibrium state. large number particles (up ) and high-resolution spatial our (1283 cells). These allow us trace dynamics until their wave amplitudes are saturated due nonlinear effects. In general, results agreement predictions....
view Abstract Citations (26) References (16) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Nonlinear Generation of One-armed Spirals in Self-gravitating Disks Laughlin, Gregory ; Korchagin, Vladimir Single-armed spiral instabilities may play an important role self-gravitating disks. However, past studies have indicated that disks which are less massive than embedded central star general linearly stable to m = 1 perturbations. In this paper, we outline how...
We present an observational and theoretical study of the spiral structure in galaxy NGC 1566. A digitized image 1566 I band, obtained with Australian National University 30 inch telescope, was used for measurements radial dependence amplitude variations arms. The azimuthal surface brightness band are about ±7% at 50'' radius increase up to 57% 100''. use known velocity dispersion disk 1566, together its rotation curve, construct linear two-dimensional nonlinear simulations, which then...
Chemical abundances of eight O- and B-type stars are determined from high-resolution spectra obtained with the MIKE instrument on Magellan 6.5m Clay telescope. The sample is selected 42 candidates membership in Leading Arm Magellanic System. Stellar parameters measured by two independent grids model atmospheres analysis procedures, confirming consistency stellar parameter results. Abundances seven elements (He, C, N, O, Mg, Si, S) for stars, as their radial velocities estimates distances...
Using recent observational data, we construct a set of multi-component equilibrium models the disk Milky Way-like galaxy. The dynamics are studied using collisionless-gaseous numerical simulations, based on joined integration equations motion for collision-less particles direct gravitational interaction and gaseous SPH-particles. We find that after approximately one Gyr, prominent central bar is formed having semi-axis length about three kpc, together with multi-armed spiral pattern...