Astronomical Applications of Astrometry: Ten Years of Exploitation of the Hipparcos Satellite Data Michael Perryman Frontmatter More Information

Cambridge University Press 978-0-521-51489-7 - Astronomical Applications of Astrometry: Ten Years of Exploitation of the Hipparcos Satellite Data Michael Perryman Frontmatter More information

Astronomical Applications of Astrometry Ten Years of Exploitation of the Hipparcos Satellite Data

The Hipparcos satellite, developed and launched by the European Space Agency (ESA) in 1989, was the first space mission dedicated to astrometry – the accurate measurement of positions, distances, and proper motions of stars. Hipparcos pinpointed more than 100 000 stars, typically 200 times more accurately than ever before. Amongst the key achievements of its measurements are refining the cosmic distance scale, characterising the large-scale kinematic motions in the solar neighbourhood, providing precise luminosities for stellar modelling, and confirming Einstein’s prediction of the effect of gravity on starlight.

This authoritative account of the Hipparcos contributions over the last decade is an outstanding reference for astronomers, astrophysicists and cosmologists. It reviews the applications of the data in different areas, describ- ing the subject and the state-of-the-art before Hipparcos, and summarising all major contributions to the topic made by Hipparcos. It contains a detailed overview of the Hipparcos and Tycho Catalogues, their annexes and their updates. Each chapter ends with comprehensive references to relevant literature.

Michael Perryman is a Research Scientist at ESA, and a Professor in the Department of Astronomy at the University of Leiden, The Netherlands. He was the Project Scientist for the Hipparcos mission from 1981 to 1997, and has won several awards for his contributions to the ﬁeld.

© Cambridge University Press www.cambridge.org Cambridge University Press 978-0-521-51489-7 - Astronomical Applications of Astrometry: Ten Years of Exploitation of the Hipparcos Satellite Data Michael Perryman Frontmatter More information

Astronomical Applications of Astrometry

Ten Years of Exploitation of the Hipparcos Satellite Data

Michael Perryman European Space Agency, Noordwijk, The Netherlands and Leiden Observatory, University of Leiden, The Netherlands

CAMBRIDGE UNIVERSITY PRESS Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, Sao˜ Paulo, Delhi Cambridge University Press The Edinburgh Building, Cambridge CB2 8RU, UK

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Contents

Preface page xv

1 The Hipparcos and Tycho Catalogues 1 1.1 Overview 1 1.2 Observation principles 1 1.3 Hipparcos Input Catalogue 4 1.4 Hipparcos Catalogue and Annexes 5 1.4.1 Hipparcos astrometry 5 1.4.2 Hipparcos photometry 11 1.4.3 Hipparcos double and multiple systems 12 1.4.4 Intermediate astrometric and transit data 12 1.4.5 Transformation of astrometric data 14 1.5 Tycho Catalogue and Annexes 15 1.5.1 Tycho astrometry 16 1.5.2 Tycho photometry 17 1.5.3 Tycho double and multiple systems 18 1.6 Post-publication Hipparcos reductions 18 1.7 Post-publication Tycho reductions 19 1.8 Catalogue products 20 1.8.1 Organisation 20 1.8.2 Availability 20 1.9 Recommended catalogues 22 1.10 Catalogue investigations post-publication 22 1.10.1 Error assessment: Internal 22 1.10.2 Error assessment: External 24 1.11 Catalogue combinations to reveal long-period binaries 27 1.12 Reference frame studies: Optical, radio and infrared 30 1.13 Radial velocities 32 1.13.1 Data to complement the Hipparcos Catalogue 32 1.13.2 Astrometric radial velocities 35 1.14 Cross-identiﬁcations 38 1.15 Relativity and astrometry 38 1.16 Astrometry beyond Hipparcos 43

2 Derived catalogues and applications 54 2.1 Introduction 54 2.2 Reference system for meridian circles 56 2.3 Reference system for astrolabes 59 2.4 Reference system for the Astrographic Catalogue and Carte du Ciel 60 2.5 Reference system for Schmidt plates 62 2.5.1 Guide Star Catalogue 64 2.5.2 USNO A1, A2, B1 65

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2.5.3 SuperCOSMOS Sky Survey 65 2.6 Other photographic surveys 69 2.6.1 Re-reduction of the AGK2 69 2.6.2 Re-reduction of the CPC2 69 2.6.3 Re-reduction of the NPM and SPM 69 2.6.4 Other photographic surveys 71 2.7 Reference system for CCD surveys 72 2.7.1 USNO catalogues: UCAC 1/2 and NOMAD 72 2.7.2 FASTT 74 2.7.3 Sloan Digital Sky Survey 74 2.7.4 Other CCD imaging systems 75 2.8 Infrared reference frame 75 2.9 Atmospheric attenuation and refraction 75 2.10 Proper motion surveys 76 2.10.1 High proper motion surveys 76 2.10.2 Other proper motions surveys 78 2.11 Parallaxes 79 2.11.1 Ground-based parallaxes 79 2.11.2 Common proper motion systems 80 2.12 Other applications 80 2.12.1 Celestial cartography 80 2.12.2 Handbooks and related compilations 82 2.12.3 Satellite and telescope operations 83 2.12.4 Education and outreach 83

3 Double and multiple stars 91 3.1 Introduction 91 3.2 Double and multiple stars in the Hipparcos Catalogue 91 3.2.1 Observational effects of multiplicity 93 3.2.2 Classiﬁcation of solutions 94 3.2.3 Accuracy veriﬁcation 96 3.3 Tycho Catalogue double stars 97 3.4 Subsequent investigations of double and multiple stars 99 3.4.1 Improved solutions 99 3.4.2 Single stars showing evidence for binarity: The µ binaries 101 3.4.3 Statistical properties 103 3.5 Orbital systems 111 3.5.1 General properties 111 3.5.2 Individual orbital systems 120 3.6 Eclipsing binaries 125 3.7 Contact binaries: W UMa, symbiotic, and RS CVn systems 130 3.8 Ground-based follow-up observations 133 3.8.1 Astrometry 133 3.8.2 Radial velocity and spectroscopy 134 3.8.3 Photometry 134 3.8.4 Speckle interferometry 134 3.8.5 Adaptive optics 138 3.8.6 Long-baseline interferometry 139

4 Photometry and variability 153 4.1 Hipparcos and Tycho photometric data 153 4.1.1 Magnitudes and photometric systems 153 4.1.2 Hipparcos and Tycho photometric systems 154 4.1.3 Main mission photometric reductions 154 4.1.4 Tycho photometric reductions 156

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4.1.5 Variability analysis 156 4.1.6 Data products 157 4.2 Photometric properties and validation 158 4.3 Photometric calibration in the optical 161 4.4 Photometric calibration in the infrared 165 4.5 Photometric calibration in the ultraviolet 165 4.6 Variability 167 4.6.1 Variability detection methods 167 4.6.2 Tycho variables 170 4.6.3 Contribution of amateur astronomers 171 4.7 Variability over the HR diagram 172 4.8 Main instability strip 173 4.8.1 Cepheid variables 173 4.8.2 W Virginis variables 174 4.8.3 RR Lyrae variables 174 4.9 Pulsators on or near the main sequence 174 4.9.1 δ Scuti variables 175 4.9.2 Rapidly-oscillating Ap (roAp) stars 181 4.9.3 γ Doradus variables 184 4.9.4 β Cephei variables 185 4.9.5 Supergiants: Pulsating O and α Cyg variables 186 4.9.6 Slowly-pulsating B stars 186 4.9.7 Maia variables 189 4.10 Red variables: Long-period, Mira, and semi-regular 189 4.11 Individual objects 197

5 Luminosity calibration and distance scale 207 5.1 Introduction 207 5.2 Statistical biases 208 5.2.1 Malmquist bias 209 5.2.2 Lutz–Kelker bias 209 5.2.3 Maximum likelihood techniques 211 5.2.4 Astrometry-based luminosity, or reduced parallax 211 5.2.5 Reduced proper motions 212 5.3 Secular and statistical parallaxes 212 5.4 Absolute magnitude versus spectral type 212 5.5 Luminosity indicators using spectral lines 219 5.5.1 Wilson–Bappu effect 220 5.5.2 Equivalent width of O I 222 5.5.3 Interstellar lines 222 5.6 Use of standard candles 223 5.7 Population I distance indicators 224 5.7.1 Classical Cepheids 224 5.7.2 Red clump giants 230 5.7.3 Mira and semi-regular variables 236 5.7.4 Other Population I distance indicators 239 5.8 Population II distance indicators 239 5.8.1 Subdwarf main-sequence ﬁtting 239 5.8.2 RR Lyrae and horizontal branch stars 246 5.8.3 Other Population II distance indicators 251 5.9 The Magellanic Clouds 253 5.9.1 Distance to the Large Magellanic Cloud 253 5.9.2 Dynamics of the Magellanic Clouds 253 5.10 Other galaxies 255 5.11 Supernovae 258

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6 Open clusters, groups and associations 273 6.1 Introduction 273 6.2 Detection methods 274 6.2.1 General considerations 274 6.2.2 Convergent-point method 275 6.2.3 Other search methods 276 6.3 The Hyades 279 6.3.1 Introduction 279 6.3.2 Convergent-point analyses 279 6.3.3 Hipparcos results 280 6.3.4 Chemical composition and theoretical models 280 6.3.5 Secular parallaxes 283 6.3.6 Further complications 285 6.3.7 N-body analyses 286 6.3.8 Summary of uncertainties 287 6.4 The Pleiades 287 6.4.1 Introduction 287 6.4.2 Hipparcos distance estimates 288 6.4.3 Main-sequence ﬁtting post-Hipparcos 290 6.4.4 Other distance estimates 292 6.4.5 Summary of the Pleiades distance 295 6.5 Distances to other nearby clusters 296 6.6 Other astrophysical applications 297 6.7 Searches for new clusters and members 298 6.8 Speciﬁc clusters 300 6.9 Kinematic groups 302 6.9.1 Introduction 302 6.9.2 Detection of kinematic groups 304 6.9.3 Origin of kinematic groups 310 6.10 Associations 311 6.10.1 Introduction 311 6.10.2 Large-scale studies 312 6.10.3 Individual associations 318 6.10.4 Young nearby streams, associations or moving groups 319 6.10.5 The Gould Belt 324

7 Stellar structure and evolution 339 7.1 Introduction 339 7.2 Observational framework and the HR diagram 340 7.2.1 Bolometric magnitudes 341 7.2.2 Effective temperatures 341 7.2.3 Surface gravities 342 7.2.4 Abundances 343 7.3 Theoretical framework 343 7.3.1 Equation-of-state and opacities 343 7.3.2 Atmospheres 345 7.3.3 Transport processes 345 7.3.4 Evolutionary tracks and isochrones 346 7.4 Fundamental parameters from Hipparcos 349 7.4.1 Bolometric magnitudes 349 7.4.2 Effective temperatures 349 7.4.3 Surface gravities 353 7.4.4 Stellar radii 355

Contents xi

7.5 Hipparcos results on stellar evolution 361 7.5.1 Nearby stars 361 7.5.2 Zero-age main sequence 365 7.5.3 Subdwarfs and other Population II stars 366 7.5.4 Subgiants 369 7.5.5 Giants 370 7.5.6 Horizontal branch 371 7.5.7 Asymptotic giant branch 373 7.5.8 Mass loss 373 7.5.9 Binary systems 375 7.5.10 Other results 377 7.6 Abundances 377 7.6.1 [Fe/H] 377 7.6.2 α-elements 378 7.6.3 Helium 379 7.6.4 Lithium 380 7.6.5 Metal-poor stars 383 7.6.6 Super metal-rich stars 385 7.6.7 Chemical enrichment of the Galaxy 386 7.7 Other stellar properties 389 7.7.1 Rotation 389 7.7.2 Magnetic ﬁeld 392 7.7.3 Imaging of surface structure 395 7.8 Asteroseismology 395

8 Specific stellar types and the ISM 413 8.1 Pre-main-sequence stars 413 8.1.1 Introduction 413 8.1.2 T Tauri stars 413 8.1.3 Herbig Ae/Be stars 419 8.2 Main-sequence evolutionary phases 421 8.2.1 Be stars 421 8.2.2 Shell stars 426 8.2.3 Chemically peculiar (Ap/Bp/Am stars) 426 8.2.4 Flare stars 427 8.2.5 λ Bootis stars 428 8.3 X-ray sources 430 8.4 Late stages of stellar evolution 438 8.4.1 Wolf–Rayet stars 438 8.4.2 Runaway stars 440 8.4.3 Carbon stars 449 8.4.4 Hydrogen-deficient carbon-rich stars 452 8.4.5 Technetium stars 452 8.4.6 Barium stars 453 8.4.7 Planetary nebulae 453 8.4.8 White dwarfs 455 8.4.9 Supernovae, pulsars, and neutron stars 464 8.5 Local interstellar medium 464 8.5.1 Local bubble 464 8.5.2 Extinction and reddening 469 8.5.3 Polarisation 474 8.5.4 Interstellar radiation field 475

9 Structure of the Galaxy 490 9.1 Introduction 490

xii Contents

9.1.1 Overall structure of the Galaxy 490 9.1.2 Hipparcos contributions 491 9.1.3 Concepts and deﬁnitions 491 9.2 The Sun within the Galaxy 495 9.2.1 Distance to the Galactic centre 495 9.2.2 Distance from the Galactic plane 496 9.2.3 Velocity dispersion and vertex deviation 497 9.2.4 Solar motion with respect to the local standard of rest 497 9.2.5 Rotation speed of the disk 499 9.2.6 Stellar kinematics in the Oort–Lindblad model 501 9.2.7 Stellar kinematics in the Ogorodnikov–Milne model 503 9.2.8 Stellar kinematics and vector harmonics 508 9.3 Census of nearby stars 509 9.4 Derived characteristics 510 9.4.1 Mass density in the solar neighbourhood 510 9.4.2 Escape velocity 514 9.4.3 Initial mass function 515 9.4.4 Star-formation rate 517 9.5 Properties of the disk 519 9.6 Properties of the bar 527 9.7 Properties of the spiral arms 530 9.8 Properties of the stellar warp 535 9.9 The stellar halo 538 9.9.1 Mass and extent 538 9.9.2 Rotation, shape and velocity dispersion 539 9.9.3 Formation 540 9.9.4 Halo substructure 542 9.10 Models of the various Galaxy components 544 9.11 Globular clusters 545 9.11.1 Introduction 545 9.11.2 Ages 547 9.11.3 Independent age estimates of the oldest halo objects 548 9.11.4 Consequences of globular cluster ages 548 9.11.5 Kinematics and dynamics 550 9.11.6 Cluster disruption 553 9.11.7 Tidal streams and the mass of the Galaxy 554 9.11.8 Individual globular clusters 555

10 Solar System and exoplanets 566 10.1 Hipparcos Solar System objects 566 10.2 Asteroids: Masses and orbits 568 10.2.1 Mass determination 568 10.2.2 Orbits and photometry 570 10.3 Planets, satellites, occultations and appulses 571 10.4 Dynamical reference system 575 10.4.1 Constraining precession 575 10.4.2 Earth rotation and polar motion 578 10.5 Passage of nearby stars 583 10.6 Earth’s climate 586 10.6.1 Maunder minimum 586 10.6.2 Sun’s orbit and the spiral arms 586 10.6.3 Sun’s orbit and Galactic plane passages 589 10.7 Exoplanets, brown dwarfs and disks 590 10.7.1 Introduction 590 10.7.2 Astrometric detection 591

Contents xiii

10.7.3 Photometric transits 598 10.7.4 Host star properties 601 10.7.5 Proto-planetary disks 604 10.7.6 Habitability and related issues 606 10.7.7 Solar twins and solar analogues 607 10.7.8 Search for extraterrestrial intelligence 609

Appendix A Numerical quantities 619 Appendix B Acronyms 623 Appendix C Author gallery 628 Index of ﬁrst authors 639 Subject index 658

Preface

The context across the Galaxy and to the Large Magellanic Cloud. Other effects will become routinely measurable at the The fundamental task of measuring stellar positions, same time. These include perspective acceleration and and the derived properties of distances and space secular parallax evolution, more subtle metric effects, motions, has preoccupied astronomers for centuries. As planetary perturbations to the photocentric motion, one of the oldest branches of astronomy, astrometry and astrometric microlensing; and at the nanoarcsec is concerned with measurement of the positions and level, currently no more than an experimental concept, motions of planets and other bodies within the Solar effects of optical interstellar scintillation, geometric cos- System, of stars within our Galaxy and, at least in prin- mology, and ripples in space-time due to gravitational ciple, of galaxies and clusters of galaxies within the Uni- waves will become apparent. The bulk of this seething verse as a whole. Accurate star positions provide a celes- motion is largely below current observational capabili- tial reference frame for representing moving objects, ties, but it is there, waiting to be investigated. and for relating phenomena at different wavelengths. Determining the systematic displacement of star positions with time gives access to their motions through Historical perspective space. Determining their apparent annual motion as the Measuring stellar distances, and their three-dimensional Earth moves in its orbit around the Sun gives access to distribution and space motions, remains a difficult task, their distances through measurement of parallax. All of even within our solar neighbourhood. John Herschel these quantities, and others, are accessed from high- (1792–1871) attempted to convey the unimaginable accuracy measurements of the relative angular sepa- interstellar distance scales with the following analogy ration of stars. Repeated measurements over a period (quoted by Allen, 1963, p153): ‘to drop a pea at the end of time provide the pieces of a celestial jigsaw, which of every mile of a voyage on a limitless ocean to the near- yield a stereoscopic map of the stars and their kinematic est fixed star, would require a fleet of 10 000 ships, each of motions. 600 tons burthen.’ What follows, either directly from the observations It is useful to place milliarcsec astrometric mea- or indirectly from modelling, are absolute physical stel- surements in a brief, albeit highly selective, historical lar characteristics: stellar luminosities, radii, masses, context. Chapman (1990) provides further fascinating and ages; and their dynamical signatures. The physical historical details of the development of angular mea- parameters are then used to understand their inter- surements in astronomy between 1500–1850. nal composition and structure, to disentangle their After the remarkable achievements of the ancient space motions and, eventually, to explain in a rigorous Greeks, including their first estimates of the sizes and and consistent manner how the Galaxy was originally distances of the Sun and Moon, the narrative inten- formed, and how it will evolve in the future. Signifi- sifies 300–400 years ago, when three main scientific cantly, space motions reflect dynamical perturbations of themes motivated the improvement of angular mea- all other matter, visible or invisible. surements: the navigational problems associated with Buried but not necessarily hidden within this frac- the determination of longitude on the Earth’s surface, tal phase-space jigsaw are a whole host of higher-order the comprehension and acceptance of Newtonianism, phenomena: at the milliarcsec level, binary star signa- and understanding the Earth’s motion through space. tures, General Relativistic light bending, and the dynam- Even before 1600, astronomers were in agreement that ical consequences of dark matter are already evident; at the crucial evidence needed to detect the Earth’s motion the microarcsec level, targeted by the next generation was the measurement of trigonometric parallax, the tiny of space astrometry missions currently under develop- oscillation in a star’s apparent position arising from the ment, direct distance measurements will be extended Earth’s annual motion around the Sun. The early British

xvi Preface

Astronomers Royal, for example, appreciated the importance of measuring stellar distances, and were very much preoccupied with the task. But it was to take a further 250 years until this particular piece of observational evidence could be secured. In 1718, Edmund Halley, who had been comparing contemporary observations with those that the Greek Hipparchus and others had made, announced that three stars, Aldebaran, Sirius and Arcturus, were displaced from their expected positions by large fractions of a degree (Halley, 1718). He deduced that each star had its own distinct velocity across the line-of-sight, or proper motion: stars were moving through space. By 1725, angular measurements had improved to a few arcsec, making it possible for James Bradley, Eng- land’s third Astronomer Royal, to detect stellar aberra- tion, as a by-product of his unsuccessful attempts to measure the distance to the bright star γ Draconis. This was an unexpected result: small positional displace- ments were detected, and correctly attributed to the vec- torial addition of the velocity of light to that of the Earth’s motion around the Sun (Bradley, 1725). His observa- Figure 1 The announcement of the selection of the Hippar- tions provided the first direct proof that the Earth was cos mission by ESA’s Science Programme Committee, which appeared in Nature, 1980 Vol 284, p 116, reprinted by permis- moving through space, and thus a confirmation both of sion from Macmillan Publishers Ltd: Nature ©1980. Copernican theory, and Roemer’s discovery of the finite velocity of light 50 years earlier. It also confirmed New- ton’s hypothesis of the enormity of stellar distances, and The following 150 years saw enormous progress, showed that the measurement of parallax would pose a with the development of accurate fundamental cata- technical challenge of extraordinary delicacy. logues, and a huge increase in quantity and quality of During the eighteenth century, the motions of many astrometric data based largely on meridian circle and more stars were announced, and in 1783 William Her- photographic plate measurements. schel found that he could partly explain these effects by assuming that the Sun itself was moving through space. Attempts to measure parallax intensified. Nevil Maske- The Hipparcos mission lyne, England’s fifth Astronomer Royal, spent seven months on the island of St Helena in 1761, using a zenith By the second half of the twentieth century, how- sector and plumb-line, in an unsuccessful attempt to ever, measurements from ground were running into measure the parallax of the bright star Sirius. essentially insurmountable barriers to improvements in Criteria for probable proximity were developed, and accuracy, especially for large-angle measurements and after many unsuccessful attempts, the first stellar paral- systematic terms; a review of the instrumental status laxes were measured in the 1830s. shortly in advance of the Hipparcos launch is given by Friedrich Bessel is generally credited as being the Monet (1988). Problems were dominated by the effects first to publish a parallax, for 61 Cygni (Piazzi’s Fly- of the Earth’s atmosphere, but were compounded by ing Star), from observations made between 1837–38. complex optical terms, thermal and gravitational instru- Thomas Henderson published a parallax for α Centauri ment flexures, and the absence of all-sky visibility. A pro- in 1839, derived from observations made in 1832–33 posal to make these exacting observations from space at the Cape of Good Hope. In 1840, Wilhelm Struve was first put forward in 1967. presented his parallax for Vega from observations in Hipparcos was the result of a long process of study 1835–1837. Confirmation that stars lay at very great but and lobby, and the first space experiment dedicated nevertheless finite distances represented a turning point to astrometry. It was accepted within the European in the understanding of the Universe. John Herschel, Space Agency’s scientific programme in 1980 (Figure 1). President of the Royal Astronomical Society at the time, It represented a major advance in physics, cost some congratulated Fellows that they had ‘lived to see the day 600 MEuro, and its execution involved some 200 Euro- when the sounding line in the Universe of stars had at last pean scientists and more than 2000 individuals in Euro- touched bottom’ (Quoted by Hoskin, 1997, p. 219). pean industry.

Preface xvii

The European Space Agency and its scientific advi- (c) Galactic kinematics and dynamics: the uniform sory structure selected the Hipparcos mission based on and accurate distances and proper motions have pro- what is referred to as the Phase A study and report (ESA, vided a substantial advance in understanding of the 1979). The underlying scientific motivation was to deter- kinematic and dynamical structure of the solar neigh- mine the physical properties of the stars through the bourhood, ranging from the presence and evolution of determination of their distances, and to place theoreti- clusters, associations and moving groups, the presence cal studies of stellar structure and evolution, and studies of resonance motions due to the Galaxy’s central bar and of Galactic structure and kinematics, on a more secure spiral arms, determination of the parameters describ- observational footing. Observationally, the objective ing Galactic rotation, discrimination of the disk and halo was to provide the positions, parallaxes, and annual populations, evidence for halo accretion, and the mea- proper motions for some 100 000 stars with an unprece- surement of space motions of runaway stars, globular dented accuracy of some 0.002 arcsec, a target in prac- clusters, and many other types of star. tice surpassed by roughly a factor of 2. Associated with these major themes, Hipparcos has The Hipparcos satellite was launched in August 1989 provided results in topics as diverse as Solar System sci- and operated until 1993. The final mission results were ence, including mass determinations of asteroids, Earth finalised in 1996, and published by ESA in June 1997 as a rotation and Chandler wobble, the internal structure of compilation of 17 hardbound volumes, a celestial atlas, white dwarfs, the masses of brown dwarfs, the charac- and six CDs, comprising the Hipparcos and Tycho Cata- terisation of exoplanets and their host stars, the height logues (ESA, 1997). Details of the satellite operation, and of the Sun above the Galactic mid-plane, the age of the the successive steps in the data analysis, and in the val- Universe, the stellar initial mass function and star for- idation and description of the detailed data products, mation rates, and search strategies for extraterrestrial are included in the published catalogue. The result have intelligence. The high-precision multi-epoch photom- been in the scientific domain for 10 years. etry has been used to measure variability and stellar pulsations in many classes of objects. The Hipparcos and Tycho Catalogues are now routinely used to point ground-based telescopes, navigate space missions, and drive public planetaria. The Hipparcos science The Hipparcos results impact a very broad range of astronomical research, which can be classified into The review three major themes: (a) The provision of an accurate reference frame: The review tackles the full range of the Hipparcos sci- this has allowed the consistent and rigorous re- entific findings, in an analysis of the scientific literature reduction of historical astrometric measurements, incl- over the 10 years since the publication of the Hippar- uding those from Schmidt plates, meridian circles, the cos and Tycho Catalogues in 1997. In this period, some 100-year old Astrographic Catalogue, and 150 years of 2000 or more papers have appeared in the refereed lit- Earth-orientation measurements. These, in turn, have erature which directly mention the Hipparcos or Tycho yielded a dense reference framework with high-accuracy Catalogues in their title or abstract. Many other papers, long-term proper motions (the Tycho 2 Catalogue). especially more recently, make use of the data. As the Reduction of current state-of-the-art survey data has catalogues become a more routine part of the day-to- yielded the dense UCAC 2 Catalogue on the same ref- day tools of astronomy, the data are frequently used erence system, and improved astrometric data from without direct attribution, or in wider-ranging applica- recent surveys such as SDSS and 2MASS. Implicit in the tions along with other types of data. This makes more high-accuracy reference frame is the measurement of direct attribution of results to the Hipparcos mission General Relativistic light bending, and the detection and harder and, eventually, of course, impossible. In their characterisation of double and multiple stars. analysis of the productivity and impact of space-based (b) Constraints on stellar structure and evolution: astronomical facilities, Trimble et al. (2006) addressed the accurate distances and luminosities of 100 000 stars this by ‘going page by page through all the issues of 19 has provided the most comprehensive and accurate journals published in 2001, and identifying all the papers dataset of fundamental stellar parameters to date, plac- that reported or analysed data from any space-based ing constraints on internal rotation, element diffusion, astronomical facility’. convective motions, and asteroseismology. Combined The broad scope of the review illustrates the breadth with theoretical models and other data it yields evolu- of science touched upon by astrometric results, and tionary masses, radii, and ages for large numbers of stars makes answering the question ‘what has the Hippar- covering a wide range of evolutionary states. cos mission achieved’ more tractable. It should set the

xviii Preface

new generation of advanced astrometric missions, now from the authors (all included with their explicit per- being developed, in a clearer context. More importantly, mission), and in a few cases from non-copyrighted www a broad review allows the implications of results in one sources. area to be traced to their impact in another. It also permits a wider understanding of the strengths and limitations of the Hipparcos data in their entirety. Acknowledgments In illustrating the range of scientific topics, I also hope that the review inspires further detailed investiga- The Hipparcos and Tycho Catalogues were the result tions based on the Hipparcos and Tycho Catalogue data. of the Hipparcos space astrometry mission, under- I have been left with the strong impression that there is taken by the European Space Agency, with the scientific aspects undertaken by nearly two hundred scientists much information remaining to be extracted from the within the NDAC, FAST, TDAC and INCA Scientific Con- catalogues, especially when taken along with data from sortia. The efforts of the many individuals and organisa- other sources. tions participating in the project over many years have I have aimed for a reasonably uniform notation been an essential component of the project’s success- throughout the volume, but in certain cases considered ful completion. Full acknowledgments for the catalogue it preferable to retain the notation of the cited article. I effort are given in the published catalogue (ESA, 1997, have modestly extended this unification to some titles of Volume 1). the cited references, where a wide range of abbreviations I am most grateful to a number of colleagues who and notations can be found. References are generally kindly reviewed the various chapters as follows: Lennart restricted to refereed publications and conference pro- Lindegren (1); Erik Høg and Norbert Zacharias (2); Dim- ceedings, although a few less mainstream references itri Pourbaix and Staffan Soderhjelm¨ (3); Laurent Eyer are included where these indicated interesting work or and Carme Jordi (4); Xavier Luri and Catherine Turon (5); other ideas in progress. Jos de Bruijne (6); Corinne Charbonnel and Yveline I stress that the work is a review, and makes marginal Lebreton (7); Ulrich Bastian (8); Walter Dehnen and claim to originality. Most of the results, conclusions, and Michael Merrifield (9); Daniel Hestroffer (10); and Jos de discussions are taken from the cited works. Where the Bruijne (Appendix A). authors have described their work, or their results, in I would also like to thank the following for specific clear and authoritative words I have not hesitated to assistance: Lennart Lindegren for guidance on various borrow from them. The review has involved consulting aspects related to the use and transformation of astro- some 5000 papers, related to the Hipparcos analyses or metric parameters (Chapter 1); Catherine Turon for con- to the background context. It provides a snapshot of tributions to the section on ground-based radial velocity the scientific relevance of positional astronomy 10 years efforts (Chapter 1); François Ochsenbein for details of after the Hipparcos and Tycho Catalogue publication. the CDS Simbad and Vizier systems (Chapter 1); Roger The broad approach offers numerous pitfalls in Sinnott and Wil Tirion for guidance on historical star terms of the depth and expertise of the analysis pre- atlases (Chapter 2); Tijl Verhoelst for information on sented. Relevant chapters are not aimed primarily for unpublished results on Arcturus (Chapter 3); Laurent those already expert on the associated topic, but rather Eyer for discussions on variability over the HR diagram (Chapter 4); Anthony Brown on interpretation of the for those looking for orientation amongst the enor- Lutz–Kelker bias, and for comments on luminosity cali- mous literature already associated with the Hipparcos bration as a function of spectral type (Chapter 5); Nancy results. Accordingly, I hope that the advantages offered Houk for the current status of the Michigan Spectral by a single-author survey outweigh the disadvantages Survey classification (Chapter 5); Michael Bessell for imposed by such a broad review. determining the Hp bolometric corrections (Chapter 7); Conscious of the role of the individual in these large Yveline Lebreton and Don VandenBerg for guidance on scientific endeavours, I have included in Appendix C the compilation of stellar evolutionary models (Chap- photographs of some of the leading authors of the vari- ter 7); Misha Haywood for clarifying some aspects of the ous Hipparcos-related papers, especially (but not exclu- chemical evolution of the Galaxy (Chapter 7); Stefan Jor- sively) those whose figures are included. I have also dan and Rainer Wehrse for helpful comments on various included a very few individuals who were not authors topics (Chapter 8); Richard Branham for assistance in of papers based on Hipparcos data, but who had some interpreting the effects stellar kinematics (Chapter 9); related involvement. This, I stress, is a selection: it does François Mignard for discussions on the Ogorodnikov– not necessarily signify the most important contribu- Milne model and the use of vector spherical harmonics tions, and for various reasons it is highly incomplete. (Chapter 9); Nicole Capitaine for clarifying various sub- Photos include some from my own collection but mostly tleties related to precession and nutation (Chapter 10);

Preface xix

and Jos de Bruijne for guidance on the current status of Mamajek, Edmundo Moreno, Christophe Perrot, Ana- the fundamental constants (Appendix A). toly Piskunov, Thomas Preibisch, Marilia Sartori, Jovan I have made extensive use of figures from the cited Skuljan, Inseok Song, Tim de Zeeuw, and Ben Zucker- articles to illustrate the topics covered, and I am grateful man. to all who authorised their use and frequently provided Chapter 7: Carlos Allende Prieto, Angel Alonso, Mar- original figures. In addition to references to the figures tin Altmann, Michael¨ Bazot, Gerard van Belle, Paolo made at the appropriate locations, I have used figures Di Benedetto, Thomas Blocker,¨ Jos de Bruijne, Bruce from the following (first) authors, almost all of whom I Carney, Corinne Charbonnel, Giuseppe Cutispoto, Dai- was able to contact to request approval: nis Dravins, Thomas Dumm, Michele Gerbaldi, David Chapter 1: Dainis Dravins, Erik Høg, Burton Jones, Guenther, Swetlana Hubrig, Mikolaj Jerzykiewicz, Raul Sergei Klioner, Martin Kurster,¨ Lennart Lindegren, Leslie Jimenez, Karin Jonsell, Torsten Kaempf, Pierre Kervella, Morrison, Fredrik Quist, Heiner Schwan, Roland Wielen, Henny Lamers, Yveline Lebreton, Earle Luck, Sushma Clifford Will, and Zi Zhu. Mallik, Maria Pia Di Mauro, Georges Meynet, Georges Chapter 2: Terry Girard, Andrew Gould, Nigel Michaud, Jose-Dias´ do Nascimento, Heidi Jo New- Hambly, Bob Hanson, Sebastien Lepine,´ Dave Monet, berg, Yuen Keong Ng, Poul Erik Nissen, Pierre North, Quentin Parker, Jeff Pier, Yves Requi´ eme,` Roger Sinnott, Sean Urban, Bruno Viateau, Jan Vondrak,´ and Norbert Francesco Palla, Harald Pohnl,¨ Maria Sofia Randich, Zacharias. Bacham Eswar Reddy, Bernardo Salasnich, Klaus-Peter Chapter 3: Christine Allen, Fred´ eric´ Arenou, Yuri Schroder,¨ Don VandenBerg, Patricia Whitelock, and Balega, Claus Fabricius, Frank Fekel, Adam Frankoswki, Sukyoung Yi. Alexey Goldin, George Gontcharov, Sylvie Jancart, Alain Chapter 8: Agnes Acker, Mario van den Ancker, Jorissen, Lennart Lindegren, Valeri Makarov, Christian Askin Ankay, Marcelo Arnal, Jacques Bergeat, David Martin, Brian Mason, Daniel Popper‡, Dimitri Pour- Berger, Bob Campbell, Fabien Carrier, Bing Chen, Fer- baix, Fredrik Quist, Ignasi Ribas, Slavek Rucinski, Selim nando Comeron,´ Sophie Van Eck, Fabio Favata, Edward Selam, Staffan Soderhjelm,¨ Anatoly Suchkov, Jocelyn Fitzpatrick, Michele Gerbaldi, Patrick Guillout, Thomas Tomkin, Guillermo Torres, and Roland Wielen. Hearty, Ulrich Heber, Ronnie Hoogerwerf, Anne Marie Chapter 4: Connie Aerts, Carlos Allende Prieto, Hubert, Fredrik Huthoff, Eric Jensen, Lex Kaper, Florian Dominique Barthes,` Michael Bessell, Fabien Carrier, Kerber, Jill Knapp, Brigitte Konig, Howard Lanning, Jean- Jørgen Christensen-Dalsgaard, Alan Cousins‡,Noel Louis Leroy, Jesus´ Ma´ız Apellaniz,´ Valeri Makarov, Sergey Cramer, Margarida Cunha, Albert Domingo, Jir´ıDusek,ˇ Marchenko, John Martin, Anne-Laure Melchior, Tony Laurent Eyer, Alejandro Garc´ıa Gil, Gerald Handler, Erik Moffat, Jorge Panei, Ernst Paunzen, John Percy, Nicola Høg, Swetlana Hubrig, Jill Knapp, Chris Koen, Patrick Pizzolato, Judith Provencal, Klaus-Peter Schroder,¨ Wies- de Laverny, Floor van Leeuwen, Hans-Michael Maitzen, law Skorzy´ nski,´ David Soderblom, Jon Sowers, Ana- Jaymie Matthews, Tarmo Oja, Jørgen Otzen Petersen, toly Suchkov, Peeter Tenjes, Gerard´ Vauclair, Jean-Luc Alexey Pamyatnykh, John Percy, Imants Platais, Gerhard Vergely, Sergio Vieira, Volker Weidemann, and Barry Scholz, and Christoffel Waelkens. Welsh. Chapter 5: Rodrigo Alvarez, Fred´ eric´ Arenou, Cecilia Chapter 9: Eugenio Carretta, Brian Chaboyer, Bing Barnbaum, Tim Bedding, Angelo Cassatella, Bing Chen, Chen, Masashi Chiba, Michel Crez´ e,´ Walter Dehnen, Andrei Dambis, Daniel Egret, Michael Feast, Edward Wilton Dias, Dana Dinescu, Sofia Feltzing, David Fitzpatrick, Leo´ Girardi, Anita Gomez,´ Andrew Gould, Fernandez,´ Klaus Fuhrmann, Andrew Gould, Amina Aaron Grocholski, Frank Grundahl, Philip Keenan‡, Helmi, Xavier Hernandez,´ David Hogg, Johan Holmberg, Pavel Kroupa, Floor van Leeuwen, Gisela Maintz, John Akihiko Ibukiyama, Hartmut Jahreiß, Raul Jimenez, Martin, Andrzej Megier, Ren´ e´ Oudmaijer, Ferhat Fikri Jacques Lepine,´ Jesus´ Ma´ız Apellaniz,´ Valeri Makarov, Ozeren,¨ Giancarlo Pace, Bohdan Paczynski´ ‡,ErnstPaun- Masanori Miyamoto, Gerhard Muhlbauer,¨ Birgitta Nord- zen, Neill Reid, Michael Richmond, Jim Sowell, Krzysztof strom,¨ Rob Olling, Alice Quillen, Neill Reid, Jerry Stanek, Don VandenBerg, Walter Wegner, and Roland Sellwood, Tanya Sitnik, Richard Smart, and Makoto Wielen. Uemura. Chapter 6: Ricard Asiain, Holger Baumgardt, Jos Chapter 10: Conard Dahn, Thomas Dall, Daniel Hes- de Bruijne, Vittorio Castellani, Bing Chen, Emmanuel troffer, Klaus Fuhrmann, Joan Garc´ıa Sanchez, Dou- Chereul, Fernando Comeron,´ Andrei Dambis, Thomas glas Gies, Jean-Louis Halbwachs, Suzanne Hawley, Guil- Dame, Benoit Famaey, Eric Feigelson, Klaus Fuhrmann, laume Hebrard,´ Paul Kalas, Chris Koen, Yuri Kolesnik, Isabelle Grenier, Jesus´ Hernandez,´ Ronnie Hoogerw- Neill Reid, Noel Robichon, Nir Shaviv, Henrik Svens- erf, Nina Kharchenko, Jeremy King, Yveline Lebreton, mark, Guillermo Torres, Margaret Turnbull, Jan Vondrak,´ Floor van Leeuwen, Søren Madsen, Valeri Makarov, Eric and Shay Zucker.

xx Preface

Sergey Marchenko kindly provided the extracted Cambridge Workshop on Cool Stars is reproduced by selection appearing as Figure 8.20, and Neill Reid kindly permission of the editors of the proceedings. provided the updated version appearing as Figure 10.22. I thank Willie Koorts for the photo of Alan Cousins, Additionally, all figures are reproduced with the per- Andre´ Heck for that of Carlos Jaschek, Fred´ eric´ Arenou mission of the respective publishers, as follows: figures for those of various colleagues, and the permission of originally published in Astronomy & Astrophysics (and Alistair Walker for use of the picture of Olin Eggen. The Supplement Series) are reproduced by permission of photo of Allan Sandage is reproduced courtesy of the the Editorial Office; figures published in the Astronom- Observatories of the Carnegie Institute of Washington. ical Journal, Astrophysical Journal, Astrophysical Jour- Preparation of the review has been made feasible in nal Letters,andAstrophysical Journal Supplement,are its current form through the extensive use of the NASA reproduced by permission of the American Astronomi- Astrophysics Data System (ADS). cal Society and the University of Chicago Press; figures The use of LATEX/Bibtex was indispensable. The published in the Publications of the Astronomical Soci- manuscript was typeset in Adobe Utopia, using Michel ety of the Pacific are reproduced by permission of the Bovani’s Fourier-GUTenberg math fonts, and made Astronomical Society of the Pacific and the University use of the following packages: graphicx (figures), cap- of Chicago Press; figures published in Monthly Notices tion (captions), natbib, bibtex and makebst (biblio- of the Royal Astronomical Society are reproduced by per- graphic references), chapterbib (chapter references), mission of Wiley–Blackwell Publishing Ltd; figures pub- authorindex (author index references and compilation), lished in the ASP Conference Series are reproduced by and makeidx (subject indexing). permission of the Astronomical Society of the Pacific IthankJoseHern´ andez´ (ESAC) for providing a Java script to extract the acronyms. Gunther Thorner,¨ Olive Conference Series; figures published in Astronomische Buggy and Liam Gretton (ESTEC) were generous in their Nachrichten are reproduced by permission of Wiley– assistance on issues of computer infrastructure. VCH Verlag GmbH & Co. KGaA; figures published in I acknowledge the support of the ESA Director of Sci- Astronomy Letters, Astrophysics and Space Science, Astro- ence, David Southwood, and the Head of the Research physics and Space Science Library,andAstronomy & and Scientific Support Department, Alvaro Gimenez,´ Astrophysics Review are reproduced by permission of during the preparation of this review. Springer Science and Business Media; figures and text I am grateful to Simon Mitton who, as commission- published in Nature are reproduced by permission of ing editor, supported my proposal to undertake this Macmillan Publishers Ltd; figures published in New review. Astronomy and Physics Reports are reproduced by per- Finally, I would like to acknowledge four broad mission of Elsevier; figures published in International groups of scientists whose work is connected with this Astronomical Union Symposium Proceedings are repro- review. First, to those who participated in the devel- duced by permission of the IAU; figures published in opment of positional astronomy from the ground over ESA publications and conference proceedings are repro- the past century or more: their creativity and meticu- duced by permission of the European Space Agency; lous skills laid the foundations and stimulated the field the figure from Annual Reviews of Astronomy & Astro- for the era of space astrometry to flourish. Second, to physics is reproduced by permission of Annual Reviews all those involved in the many aspects of the Hippar- of Astronomy & Astrophysics; the figure from Acta Astro- cos space astrometry mission, within ESA, industry, and nomica is reproduced by permission of the editor; the the scientific community; it was a remarkable collabo- figure from Publications of the Astronomical Society of ration which provided the basics for a wealth of scien- Japan is reproduced by permission of the Astronomical tific investigation. Third, to those now involved in ESA’s Society of Japan; the figure from Living Reviews in Rel- Gaia mission, which will move the frontiers of scientific ativity is reproduced by permission of Living Reviews understanding in this area in an even more dramatic in Relativity; the figure from Monthly Notes of the Astro- manner; the Hipparcos discoveries should underline its nomical Society of South Africa is reproduced by permis- importance. Fourth, to all those who used the Hipparcos sion of Astronomical Society of South Africa; the figure and Tycho Catalogues for their own scientific research from Revista Mexicana de Astronom´ıa y Astrof´ısica (Serie and, through their own ingenuity and questioning, pro- de Conferencias) is reproduced by permission of Revista duced the results presented here. Mexicana de Astronom´ıa y Astrof´ısica; the figure from Science is reproduced by permission of the American Association for the Advancement of Science; the figure from the Contributions of the Astronomical Observatory References of Skalnate Pleso is reproduced by permission of the Allen RH, 1963, Star Names: Their Lore and Meaning.Dover Slovak Academy of Sciences; the figure from the 12th Republication {xv}

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Bradley J, 1725, A letter to Dr Halley giving account of a new volumes including 6 CDs). European Space Agency, Noord- discovered motion of the ﬁxed stars. Phil. Trans., 35, 640 wijk, also: VizieR Online Data Catalogue {xvii, xviii} {xvi} Halley E, 1718, Considerations on the change of the latitude Chapman A, 1990, Dividing the Circle: the Development of of some of the principal ﬁxed stars. Phil. Trans., 30, 736– Critical Angular Measurement in Astronomy 1500–1850. 738 {xvi} Ellis Horwood, London {xv} Hoskin M, 1997, Cambridge Illustrated History of Astronomy. ESA, 1979, Hipparcos Space Astrometry: Report on the Phase A Cambridge University Press {xvi} Study, ESA SCI(79)10. European Space Agency, Noordwijk Monet DG, 1988, Recent advances in optical astrometry. {xvii} ARA&A, 26, 413–440 {xvi} ESA, 1997, The Hipparcos and Tycho Catalogues. Astromet- Trimble V, Zaich P, Bosler T, 2006, Productivity and impact ric and Photometric Star Catalogues derived from the ESA of space-based astronomical facilities. PASP, 118, 651– Hipparcos Space Astrometry Mission, ESA SP–1200 (17 655 {xvii}