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In kinetic theory, the classic $n \Sigma v$ approach calculates the rate of particle interactions from local quantities: the number density of particles $n$, the cross-section $\Sigma$, and the average relative speed $v$. In stellar…

High Energy Astrophysical Phenomena · Physics 2025-08-07 Elisha Modelevsky , Nicholas C. Stone , Re'em Sari

We present a self consistent nonparametric model of the local cosmic velocity field based on the density distribution in the PSCz redshift survey of IRAS galaxies. The error analysis, carried out on mock PSCz catalogues constructed from…

The line profiles of the stars with v sin i below a few km/s can reveal direct signatures of local velocity fields (e.g. convection) in stellar atmospheres. This effect is well established in cool main sequence stars, and has been detected…

Solar and Stellar Astrophysics · Physics 2009-12-03 J. D. Landstreet , F. Kupka , H. A. Ford , T. Officer , T. A. A. Sigut , J. Silaj , S. Strasser , A. Townshend

Spectroscopic surveys now supply precise stellar label measurements such as element abundances for large samples of stars throughout the Milky Way. These element abundances are known to correlate with orbital actions or other dynamical…

The kinematic parameters identified from high-velocity stars situated within 100 kpc are examined and analyzed. We included three high velocity programs comprising 591, 87, and 519 stars as a function of distances ranging from 0.10 to…

Solar and Stellar Astrophysics · Physics 2025-01-23 W. H. Elsanhoury

The parameters of the Galactic spiral wave are re-determined using a modified periodogram (spectral) analysis of the galactocentric radial velocities of 58 masers with known trigonometric parallaxes, proper motions, and line-of-site…

Astrophysics of Galaxies · Physics 2015-06-15 A. T. Bajkova , V. V. Bobylev

Future microwave sky surveys will have the sensitivity to detect the kinematic Sunyaev-Zeldovich signal from moving galaxy clusters, thus providing a direct measurement of their line-of-sight peculiar velocity. We show that cluster peculiar…

Astrophysics · Physics 2009-11-11 Suman Bhattacharya , Arthur Kosowsky

We present the line-of-sight (LOS) velocities for 13 distant main sequence Milky Way halo stars with published proper motions. The proper motions were measured using long baseline (5-7 years) multi-epoch HST/ACS photometry, and the LOS…

We study the global consequences in the halos of spiral galaxies of the steady, axially symmetric, mean field dynamo. We use the classical theory but add the possibility of using the velocity field components as parameters in addition to…

Astrophysics of Galaxies · Physics 2017-06-21 R. N. Henriksen

Context. Recently our ability to study stars using asteroseismic techniques has increased dramatically, largely through the use of space based photometric observations. Work has also been done using ground based spectroscopic observations…

Solar and Stellar Astrophysics · Physics 2018-10-03 Jesper Schou

Future X-ray missions, such as NICER and LOFT, together with gravitational-wave observations from ground-based detectors, will provide new insights into neutron stars. Interpreting accurate observations in the future will require accurate…

General Relativity and Quantum Cosmology · Physics 2025-05-27 Carlos Conde-Ocazionez , Tuojin Yin , Jaquelyn Noronha-Hostler , Nicolás Yunes

A new method for measuring deviations from axisymmetry in the velocity fields of gas disks is presented. The method is an extension of the method that Franx, van Gorkom and de Zeeuw developed for a single orbit gas ring. The measurement is…

Astrophysics · Physics 2007-05-23 R. H. M. Schoenmakers

(context) Different cosmological data are consistent with an accelerated expansion produced by an exotic matter-energy component, dubbed "dark-energy''. A cosmological constant is a possibility since it satisfies most of the observational…

Astrophysics · Physics 2010-01-15 Sébastien Peirani , José Antonio De Freitas Pacheco

We determine here peculiar motion of the Solar system, first time from the $m-z$ Hubble diagram of quasars. Observer's peculiar motion causes a systematic shift in the $m-z$ plane between sources lying along the velocity vector and those in…

Cosmology and Nongalactic Astrophysics · Physics 2022-07-14 Ashok K. Singal

In a previous work (Mbelek 2001), we modelled the rotation curves (RC) of spiral galaxies by including in the equation of motion of the stars the dynamical terms from an external real self-interacting scalar field, $\psi$, minimally coupled…

General Relativity and Quantum Cosmology · Physics 2014-11-17 J. P. Mbelek

The discrepancy between estimates of the Hubble Constant ($H_0$) measured from local ($z \lesssim 0.1$) scales and from scales of the sound horizon is a crucial problem in modern cosmology. Peculiar velocities ($v_{pec}$) of standard candle…

Cosmology and Nongalactic Astrophysics · Physics 2020-11-18 Thomas M. Sedgwick , Chris A. Collins , Ivan K. Baldry , Philip A. James

We consider a measure of the peculiar velocity field derived from the Mark III compilation of 2900 spiral galaxies (Willick \etal 1996b), using an analysis that is substantially free of bias (Nusser and Davis 1995). We expand the velocity…

Astrophysics · Physics 2009-10-28 Marc Davis , Adi Nusser , Jeff Willick

In this paper we follow an effective theory approach to study the nonrelativistic limit of a selfgravitating and selfinteracting massive vector field. Our effective theory is characterized by three parameters: the field's mass $m_0$ and the…

General Relativity and Quantum Cosmology · Physics 2025-03-28 Emmanuel Chávez Nambo , Alberto Diez-Tejedor , Edgar Preciado-Govea , Armando A. Roque , Olivier Sarbach

We have measured the cosmic momentum power spectrum from the peculiar velocities of galaxies in the SFI sample. The SFI catalog contains field spiral galaxies with radial peculiar velocities derived from the I-band Tully-Fisher relation. As…

Astrophysics · Physics 2009-11-13 Chan-Gyung Park , Changbom Park

We use about 15,000 F/G nearby dwarf stars selected from the LAMOST pilot survey to map the U-V velocity distribution in the solar neighbourhood. An extreme deconvolution algorithm is applied to reconstruct an empirical multi-Gaussian…

Astrophysics of Galaxies · Physics 2014-12-17 Qiran Xia , Chao Liu , Yan Xu , Shude Mao , Shuang Gao , Yonghui Hou , Ge Jin , Yong Zhang