The Gaia-ESO Survey: Empirical determination of the precision of stellar radial velocities and projected rotation velocities

Context. The Gaia-ESO Survey (GES) is a large public spectroscopic survey at the European Southern Observatory Very Large Telescope. Aims. A key aim is to provide precise radial velocities (RVs) and projected equatorial velocities (vsini) for representative samples of Galactic stars, which will complement information obtained by the Gaia astrometry satellite. Methods. We present an analysis to empirically quantify the size and distribution of uncertainties in RV and vsini using spectra from repeated exposures of the same stars. Results. We show that the uncertainties vary as simple scaling functions of signal-to-noise ratio (S/N) and vsini, that the uncertainties become larger with increasing photospheric temperature, but that the dependence on stellar gravity, metallicity and age is weak. The underlying uncertainty distributions have extended tails that are better represented by Student’s t-distributions than by normal distributions. Conclusions. Parametrised results are provided, which enable estimates of the RV precision for almost all GES measurements, and estimates of the vsini precision for stars in young clusters, as a function of S/N, vsini and stellar temperature. The precision of individual high S/N GES RV measurements is 0.22–0.26 km s-1, dependent on instrumental configuration.

Earth’s Rotation: A Challenging Problem in Mathematics and Physics

A suitable knowledge of the orientation and motion of the Earth in space is a common need in various fields. That knowledge has been ever necessary to carry out astronomical observations, but with the advent of the space age, it became essential for making observations of satellites and predicting and determining their orbits, and for observing the Earth from space as well. Given the relevant role it plays in Space Geodesy, Earth rotation is considered as one of the three pillars of Geodesy, the other two being geometry and gravity. Besides, research on Earth rotation has fostered advances in many fields, such as Mathematics, Astronomy and Geophysics, for centuries. One remarkable feature of the problem is in the extreme requirements of accuracy that must be fulfilled in the near future, about a millimetre on the tangent plane to the planet surface, roughly speaking. That challenges all of the theories that have been devised and used to-date; the paper makes a short review of some of the most relevant methods, which can be envisaged as milestones in Earth rotation research, emphasizing the Hamiltonian approach developed by the authors. Some contemporary problems are presented, as well as the main lines of future research prospected by the International Astronomical Union/International Association of Geodesy Joint Working Group on Theory of Earth Rotation, created in 2013.

La rotation de la terre : ses preuves mécaniques anciennes et nouvelles /

Includes index.

Rotation de l'ellipsoide hétérogène et figure exacte de la terre.

Thèse - Faculté des sciences de Paris.

Théorie géométrique des engrenages : destinés à transmettre le mouvement de rotation entre deux axes situés ou non situés dans un même plan /

Mode of access: Internet.

Dynamics of rotation; an elementary introduction to rigid dynamics,

Mode of access: Internet.

Dynamics of rotation. an elementary introduction to rigid dynamics /

Mode of access: Internet.

Permanent pasture compared with a 5-year crop-and-pasture rotation for dairy cattle feed /

Caption title.

The rotation period of the sun as determined from the motion of the calcium flocculi

Mode of access: Internet.

A low insertion loss, capacitively scanned goniometer for Faraday rotation measurements in the V.H. F. range

Mode of access: Internet.

Mémoire sur la vision des couleurs matérielles en mouvement de rotation : et des vitesses numériques de cercles dont une moitié diamétrale est colorée et l'autre blanche, vitesses correspondant à trois périodes de leur mouvement à partir de l'extreme vitesse jusqu'au repos. /

"Note de M. Becquerel," p. [363]-366.

Transverse-Plane Ankle Rotation for Lower-Limb Amputees Using Two Novel Prostheses

Thesis (Ph.D.)--University of Washington, 2016-06

Non-timber values and the optimal forest rotation: An application to the southern forest of Tasmania

The present paper examines the optimal use of a site containing standing timber, taking account of both timber and non-timber values. Using a site in the southern forest of Tasmania for illustrative purposes, it calculates the relationships between age of stand, extent of timber and non-timber values and optimal cutting age. It finds that, for a stand with moderate potential environmental benefits, there is a period of its life during which it is optimal to log. This segment narrows, and eventually disappears, as potential environmental benefits increase.