- ISBN 13: 9780521514897
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New York: Praxis Publishing Ltd. Laskov, Lasko M. Computing 7 4 : Schntzenberger, Paris. Perryman, Michael. Astronomical applications of astrometry: Ten years of exploitation of the Hipparcos satellite data. Cambridge: Cambridge University Press.
ISBN 13: 9780521514897
Randazzo, Donatella. Tosaka, Yuji, and Cathy Weng. Vaquero, J.
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Gaia: Gaia is only the second space astrometry mission developed and launched, despite many attempted national initiatives in US, Russia, Germany, and Japan. Many of those who had been involved for many years in the project, and others from beyond Europe, gathered in the beautiful island location of San Giorgio, Venice, to inspect its content. As a catalogue of star positions as they were arranged in the sky around , it maps a configuration which will never be seen again. As such, astrometry bestows a rare treasure in science; it provides a unique snapshot of the Universe at one moment, preserved for all time.
It may diminish in relevance as future star catalogues from space build upon it, but its historical value will persist indefinitely. ESA says thank you to them and the many other scientists who devoted twenty or thirty years of their working lives to making Hipparcos a success. Several thousand scientific papers based on the catalogues have appeared since An extensive compilation of these various scientific results, with references, is given in my book review of the Hipparcos scientific results Perryman, This has allowed the consistent and rigorous re-reduction of a wide variety of historical and present-day astrometric measurements.
The Astrographic Catalogue data, in particular, have yielded a dense reference framework reduced to the Hipparcos reference system propagated back to the early s. Combined with the dense framework of 2. Many other proper motion compilations have been generated based on the Hipparcos reference system, in turn yielding large data sets valuable for open cluster surveys, common-proper motion surveys, etc.
New binary systems have been followed up through speckle and long-baseline optical interferometry from ground, through a re-analysis of the Hipparcos Intermediate Astrometric Data, or through a combined analysis of astrometric and ground-based radial velocity data.
Other binaries have been discovered as common-proper motion systems in catalogues reaching fainter limiting magnitudes. These radial velocity measurements are of considerable importance for determining the three-dimensional space motions, as well as further detecting and characterising the properties of binary stars. More astrophysically, studies have been made of wide binaries, and their use as tracers of the mass concentrations during their Galactic orbits, and according to population.
A number of papers have determined the statistical distributions of periods and eclipse depths for eclipsing binaries, and others have addressed their important application in determining the radiative flux and temperature scales.
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- ASTRONOMICAL APPLICATIONS OF ASTROMETRY - TEN YEARS OF EXPLOITATION OF THE HIPPARCOS SATELLITE DATA.
- Astronomical Applications of Astrometry: Ten Years of Exploitation of the Hipparcos Satellite Data.
Combined with theoretical models it yields evolutionary masses, radii, and stellar ages of large numbers and wide varieties of stars. The Cepheids are also targets for Galactic kinematic studies, tracing out the Galactic rotation, and also the motion perpendicular to the Galactic plane. Hipparcos has revolutionised the use of red clump giants as distance indicators, by providing accurate luminosities of hundreds of nearby systems, in sufficient detail that metallicity and evolutionary effects can be disentangled, and the objects then used as single-step distance indicators to the Large and Small Magellanic Clouds, and the Galactic bulge.
Availability of these data has catalysed the parallel theoretical modeling of the clump giants. A wide range of other studies has made use of the Hipparcos data to provide constraints on stellar structure and evolution.
Improvements have followed in terms of effective temperatures, metallicities, and surface gravities. Bolometric corrections for the Hp photometric band have opened the way for new and improved studies of the observational versus theoretical Hertzsprung—Russell diagram. Studies of elemental abundance variations include the age—metallicity relation in the solar neighbourhood, and various questions related to particular elemental abundances such as lithium and helium.
The understanding of Be stars, chemically-peculiar stars, X-ray emitters, and Wolf—Rayet stars have all been substantially effected by the Hipparcos data.
One of the most curious of the Hipparcos results in this area is the improved determination of the empirical mass—radius relation of white dwarfs. At least three such objects appear to be too dense to be explicable in terms of carbon or oxygen cores, while iron cores seem difficult to generate from evolutionary models. Many attempts have been made to further understand and characterise the solar motion based on Hipparcos data, and to redefine the large-scale properties of Galactic rotation in the solar neighbourhood. The latter has been traditionally described in terms of the Oort constants, but it is now evident that such a formulation is quite unsatisfactory in terms of describing the detailed local stellar kinematics.
Attempts have been made to re-cast the problem into the 9-component tensor treatment of the Ogorodnikov—Milne formulation, analogous to the treatment of a viscous and compressible fluid by Stokes more than years ago. The results of several such investigations have proved perplexing. They reveal the warp at the same time, but in an opposite sense to the vector field expected from a stationary warp. Kinematic analyses have tackled the issues of the mass density in the solar neighbourhood, and the associated force-law perpendicular to the plane, the K z relation.
Related topics include studies of nearby stars, the stellar escape velocity, the associated initial mass function, and the star formation rate over the history of the Galaxy. Dynamical studies of the bar, of the spiral arms, and of the stellar warp, have all benefited. Studies of the baryon halo of the Galaxy have refined its mass and extent, its rotation, shape, and velocity dispersion, and have provided compelling evidence for its formation in terms of halo substructure, some of which is considered to be infalling, accreting material, still ongoing today.
New techniques have been developed and refined to search for phase-space structure i. An extensive literature has resulted on many aspects of the Hyades, the Pleiades, and other nearby open clusters, comprehensive searches for new clusters, and their application to problems as diverse as interstellar reddening determination, correlation with the nearby spiral arms, and the age dependence of their vertical distribution within the Galaxy: one surprising result is that this can be used to place constraints on the degree of convective overshooting by matching stellar evolutionary ages with cluster distances from the Galactic plane.
In addition to studying and characterising open clusters, and young nearby associations of recent star formation, the Hipparcos data have revealed a wealth of structure in the nearby velocity distribution which is being interpreted in terms of open cluster evaporation, resonant motions due to the central Galactic bar, scattering from nearby spiral arms, and the effects of young nearby kinematic groups, with several having been discovered from the Hipparcos data in the past few years.
The interstellar medium morphology, extinction and reddening, grey extinction, polarisation of star light, and the interstellar radiation field, have all been constrained by these new distance estimates of the Hipparcos stars. Studies of the passage of nearby stars and their possible interaction with the Oort Cloud have identified stars which came close to the Sun in the geologically recent past, and others which will do so in the relatively near future. In addition to all of these, the Hipparcos and Tycho Catalogues are now routinely used to point ground-based telescopes, navigate space missions, drive public planetaria, and provide search lists for programmes such as exoplanet surveys; one study has even shown how positions of nearby stars at the milliarcsec level can be used to optimise search strategies for extraterrestrial intelligence.
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Hipparcos left another important legacy, beyond that of the scientific advance that it provided. The results, and the acquisition of the technical and scientific knowledge it entailed, inspired a number of new satellite studies intended to advance the field further. The somewhat comparable accuracy Japanese mission Nano-Jasmine, remains under development, with launch foreseen in