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We present the decomposition of the stellar velocity ellipsoid using stellar velocity dispersions within a 40 deg wedge about the major-axis (sigma_maj), the epicycle approximation, and the asymmetric drift equation. Thus, we employ no…

We study the kinematics of a local sample of stars, located within a cylinder of 500 pc radius centered on the Sun, in the RAVE dataset. We find clear asymmetries in the $v_R$-$v_\phi$ velocity distributions of thin and thick disk stars:…

We infer the intrinsic ionised gas kinematics for 383 star-forming galaxies across a range of integrated star-formation rates (SFR $\in [10^{-3}, 10^2]$ M$_\odot$ yr$^{-1}$) at $z \lesssim 0.1$ using a consistent 3D forward-modelling…

Superthin galaxies are a class of bulgeless, low surface brightness galaxies with strikingly high values of planar-to-vertical axes ratio $\rm(b/a> 10 - 20)$, possibly indicating the presence of an ultra-cold stellar disc. Using the…

Astrophysics of Galaxies · Physics 2021-01-29 K. Aditya , Arunima Banerjee

In order to investigate the correlation between the circular velocity Vc and the central velocity dispersion of the spheroidal component sigma_c, we analyzed these quantities for a sample of 40 high surface brightness disc galaxies…

Astrophysics · Physics 2009-11-10 A. Pizzella , E. M. Corsini , E. Dalla Bonta' , M. Sarzi , L. Coccato , F. Bertola

We present spectroscopic observations of the stellar motions in the disk of the superthin edge-on spiral galaxy IC 5249 and re-analyse synthesis observations of the HI. We find that the HI rotation curve rises initially to about 90-100…

Astrophysics · Physics 2009-11-07 P. C. van der Kruit , J. Jimenez-Vicente , M. Kregel , K. C. Freeman

In this paper, we aim to estimate the vertical gradients in the rotational velocity of the Galaxy. This is carried out in the framework of a global thin disc model approximation. The predicted gradient values coincide with the observed…

Astrophysics of Galaxies · Physics 2015-03-13 Joanna Jałocha , Łukasz Bratek , Marek Kutschera , Piotr Skindzier

From the derived stellar density profile using LAMOST giant stars, we find that the Galactic disk does not show truncation or break, but smoothly transit to the halo from 19 kpc. The scale length of the outer disk is only $1.6\pm0.1$\,kpc,…

Astrophysics of Galaxies · Physics 2018-08-22 Chao Liu , Yan Xu , Haifeng Wang , Junchen Wan

To calibrate stellar velocity dispersion measurements from optical and near-IR stellar lines, and to improve the black hole mass (MBH)- stellar velocity dispersion (sigma) relation, we measure stellar velocity dispersions based on high…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Wol-Rang Kang , Jong-Hak Woo , Andreas Schulze , Dominik A. Riechers , Sang Chul Kim , Daeseong Park , Vernesa Smolcic

We estimated the dynamical surface mass density (Sigma) at the solar Galactocentric distance between 2 and 4 kpc from the Galactic plane, as inferred from the observed kinematics of the thick disk. We find Sigma(z=2 kpc)=57.6+-5.8 Mo pc^-2,…

Astrophysics of Galaxies · Physics 2015-05-20 C. Moni Bidin , G. Carraro , R. A. Mendez , W. F. van Altena

We analyze the distribution of G and K type stars towards the Galactic poles using RAVE and ELODIE radial velocities, 2MASS photometric star counts, and UCAC2 proper motions. The combination of photometric and 3D kinematic data allows us to…

Using a new algorithm for estimating the actions of orbits a parametrised distribution function is automatically fitted to observational data for the solar neighbourhood. We adopt a gravitational potential that is generated by three discs…

Astrophysics of Galaxies · Physics 2015-06-05 James Binney

Making use of public spectra from Cimatti et al (2008), we measure for the first time the velocity dispersion of spheroid-like massive (M_star ~ 10^11 M_sun) galaxies at z ~ 1.6. By comparing with galaxies of similar stellar mass at lower…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 A. Javier Cenarro , Ignacio Trujillo

We present evidence for a ring of stars in the plane of the Milky Way, extending at least from l = 180 deg to l = 227 deg with turnoff magnitude $g \sim 19.5$; the ring could encircle the Galaxy. We infer that the low Galactic latitude…

The velocity dispersion of the ultra diffuse galaxy NGC1052-DF2 was found to be $\sigma_{\rm gc}=7.8^{+5.2}_{-2.2} \ \mathrm{kms^{-1}}$, much lower than expected from the stellar mass -- halo mass relation and nearly identical to the…

Astrophysics of Galaxies · Physics 2019-04-03 Shany Danieli , Pieter van Dokkum , Charlie Conroy , Roberto Abraham , Aaron J. Romanowsky

The velocity distribution of galaxies in clusters is not universal; rather, galaxies are segregated according to their spectral type and relative luminosity. We examine the velocity distributions of different populations of galaxies within…

We determined the chemical and kinematic properties of the Galactic thin and thick disk using a sample of 307,246 A/F/G/K-type giant stars from the LAMOST spectroscopic survey and Gaia DR2 survey. Our study found that the thick disk…

Astrophysics of Galaxies · Physics 2019-07-31 Yepeng Yan , Cuihua Du , Shuai Liu , Hefan Li , Jianrong Shi , Yuqin Chen , Jun Ma , Zhenyu Wu

Galactic disk warp has been widely characterized by stellar distributions and stellar kinematics but has not been traced by stellar chemistry. Here, we use a sample with over 170,000 red clump (RC) stars selected from LAMOST and APOGEE…

Astrophysics of Galaxies · Physics 2024-12-18 Weixiang Sun , Han Shen , Biwei Jiang , Xiaowei Liu

Using nearly 230,000 red clump (RC) stars selected from LAMOST and Gaia, we conduct a comprehensive analysis of the stellar age-velocity dispersion relations (AVRs) for various disk populations, within 5.0 $\leq$ $R$ $\leq$ 15.0 kpc and…

Astrophysics of Galaxies · Physics 2025-01-07 Weixiang Sun , Han Shen , Biwei Jiang , Xiaowei Liu