The Distribution of Nearby Stars in Phase Space Mapped by Hipparcos : the Potential Well
نویسنده
چکیده
Hipparcos data provide the rst, volume limited and absolute magnitude limited homogeneous tracer of stellar density and velocity distributions in the solar neighbourhood. The density of A-type stars more luminous than M v = 2:5 can be accurately mapped within a sphere of 125 pc radius, while proper motions in galactic latitude provide the vertical velocity distribution near the galactic plane. The potential well across the galactic plane is traced practically hypothesis-free and model-free. The local dynami-cal density comes out as 0 = 0:076 0:015M pc ?3 a value well below all previous determinations leaving no room for any disk shaped component of dark matter.
منابع مشابه
The distribution of nearby stars in phase space mapped by Hipparcos ⋆ I . The potential well and local dynamical mass
Hipparcos data provide the first, volume limited and absolute magnitude limited homogeneous tracer of stellar density and velocity distributions in the solar neighbourhood. The density of A-type stars more luminous than M v = 2.5 can be accurately mapped within a sphere of 125 pc radius, while proper motions in galactic latitude provide the vertical velocity distribution near the galactic plane...
متن کاملThe distribution of nearby stars in phase space mapped by Hipparcos ?
Hipparcos data provide the first, volume limited and absolute magnitude limited homogeneous tracer of stellar density and velocity distributions in the solar neighbourhood. The density of A-type stars more luminous than M v = 2.5 can be accurately mapped within a sphere of 125 pc radius, while proper motions in galactic latitude provide the vertical velocity distribution near the galactic plane...
متن کاملThe Distribution of Nearby Stars in Phase Space Mapped by Hipparcos 2-wavelet Analysis of 3d-density and 2d-velocity Distributions
A volume limited and absolute magnitude limited sample of A-type dwarfs within 125 parsecs of the Sun is searched for inhomogeneities in the density-velocity space, expecting some signatures of the cluster melting, phase mixing and possibly of the disc heating mechanisms. This sample has been wavelet analysed to nd a-periodic structures in both 3-d position and 2-d velocity distributions. In th...
متن کاملThe local density of matter mapped by Hipparcos
We determine the velocity distribution and space density of a volume complete sample of A and F stars, using parallaxes and proper motions from the Hipparcos satellite. We use these data to solve for the gravitational potential vertically in the local Galactic disc, by comparing the Hipparcos measured space density with predictions from various disc models. We derive an estimate of the local dy...
متن کاملThe Distribution of Nearby Stars in Velocity Space
From the tangential velocities of stars all over the sky, one can, in a statistical way, infer their 3D velocity distribution. An application to Hipparcos data reveals rich structure in the planar stellar motions: there are several moving groups, increasing in number with stellar type but decreasing in importance. A distinct group of outward moving stars with low rotation velocities might be as...
متن کامل