Scale length of the galactic thin disk

AbstractBased on observational data from the fourth internal data release of the Gaia-ESO Survey we probe the abundance structure in the Milky Way stellar disk as a function of galactocentric radius and height above the plane. We find that the inner and outer Galactic disks have different chemical signatures. The stars in the inner Galactic disk show abundance signatures of both the thin and thick disks, while the stars in the outer Galactic disk resemble in majority the abundances seen in the thin disk. Assuming that the Galactic thick disk can be associated with the α-enriched population, this can be interpreted as that the thick disk density drops drastically beyond a galactocentric radius of about 10 kpc. This is in agreement with recent findings that the thick disk has a short scale-length, shorter than that of the the thin disk.

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2MASS Star Counts and Galactic Structure

Symposium - International Astronomical Union ◽

10.1017/s0074180900226090 ◽

2001 ◽

Vol 204 ◽

pp. 213-213

Author(s):

D. K. Ojha

Keyword(s):

Near Infrared ◽

Local Density ◽

Global Analysis ◽

Thin Disk ◽

Thick Disk ◽

Sky Survey ◽

Radial Structure ◽

Thin And Thick Disks ◽

Density Scale ◽

Scale Length

This paper presents a global analysis of the first 2MASS (Two Micron All Sky Survey) data as observed in seven fields at different Galactic latitudes. These new data lead to strong constraints on the radial structure of the Galactic thin and thick disks. The interpretation of star counts and color distributions of stars in the near-infrared with a synthetic stellar population model provides strong evidence that the Galactic thin disk density scale length, hR, is rather short (2.8±0.3 kpc). The Galactic thick disk population is revisited in the light of new data. We find the thick disk to have a local density of 3.5 ± 2.0% of the thin disk, exponential scale height, hz, of 860±200 pc and exponential scale length, hR, of

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Estimation of the Radial Scale Length and Vertical Scale Height of the Galactic Thin Disk from Cepheids

Astronomy Letters ◽

10.1134/s1063773721070033 ◽

2021 ◽

Vol 47 (8) ◽

pp. 534-543

Author(s):

V. V. Bobylev ◽

A. T. Bajkova

Keyword(s):

Thin Disk ◽

Scale Height ◽

Vertical Scale ◽

Scale Length

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On the accuracy of the binary-collision algorithm in particle-in-cell simulations of magnetically confined fusion plasmas

Journal of Plasma Physics ◽

10.1017/s0022377821000398 ◽

2021 ◽

Vol 87 (2) ◽

Author(s):

Timo P. Kiviniemi ◽

Eero Hirvijoki ◽

Antti J. Virtanen

Keyword(s):

Finite Difference ◽

Electric Fields ◽

Finite Size ◽

Binary Collision ◽

Conserved Quantities ◽

Fusion Plasmas ◽

Fusion Plasma ◽

Particle In Cell ◽

Magnetically Confined ◽

Scale Length

Ideally, binary-collision algorithms conserve kinetic momentum and energy. In practice, the finite size of collision cells and the finite difference in the particle locations affect the conservation properties. In the present work, we investigate numerically how the accuracy of these algorithms is affected when the size of collision cells is large compared with gradient scale length of the background plasma, a parameter essential in full- $f$ fusion plasma simulations. Additionally, we discuss implications for the conserved quantities in drift-kinetic formulations when fluctuating magnetic and electric fields are present: we suggest how the accuracy of the algorithms could potentially be improved with minor modifications.

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Numerical and Experimental Analysis of Yb:YAG Thin Disk Regenerative Amplifier

IEEE Photonics Journal ◽

10.1109/jphot.2021.3080708 ◽

2021 ◽

pp. 1-1

Author(s):

Di Sun ◽

Jie Guo ◽

Wei Wang ◽

Xiao Du ◽

Yongxi Gao ◽

...

Keyword(s):

Experimental Analysis ◽

Thin Disk ◽

Regenerative Amplifier

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Kinematics of Disk Stars in the Solar Neighbourhood

Highlights of Astronomy ◽

10.1017/s1539299600022310 ◽

1998 ◽

Vol 11 (1) ◽

pp. 574-574

Author(s):

A.E. Gómez ◽

S. Grenier ◽

S. Udry ◽

M. Haywood ◽

V. Sabas ◽

...

Keyword(s):

Dispersion Relation ◽

Radial Velocity ◽

Velocity Dispersion ◽

Tangential Velocity ◽

Thin Disk ◽

The Other ◽

Proper Motions ◽

Velocity Data ◽

Kinematic Data ◽

Radial Velocity Data

Using Hipparcos parallaxes and proper motions together with radial velocity data and individual ages estimated from isochones, the velocity ellipsoid has been determined as a function of age. On the basis of the available kinematic data two different samples were considered: a first one (7789 stars) for which only tangential velocities were calculated and a second one containing 3104 stars with available U, V and W velocity components and total velocities ≤ 65 km.s-1. The main conclusions are: -Mixing is not complete at about 0.8-1 Gyr. -The shape of the velocity ellipsoid changes with time getting rounder from σu/σv/σ-w = 1/0.63/0.42 ± 0.04 at about 1 Gyr to1/0.7/0.62 ±0.04 at 4-5 Gyr. -The age-velocity-dispersion relation (from the sample with kinematical selection) rises to a maximum, thereafter remaining roughly constant; there is no dynamically significant evolution of the disk after about 4-5 Gyr. -Among the stars with solar metallicities and log(age) > 9.8 two groups are identified: one has typical thin disk characteristics, the other is older than 10 Gyr and lags the LSR at about 40 km.s-1 . -The variation of the tangential velocity with age(without selection on the tangential velocity) shows a discontinuity at about 10 Gyr, which may be attributed to stars typically of the thick disk populations for ages > 10 Gyr.

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