Book contents
- Frontmatter
- Contents
- List of contributors
- List of acronyms
- Preface
- Part I Astrometry in the twenty-first century
- Part II Foundations of astrometry and celestial mechanics
- Part III Observing through the atmosphere
- Part IV From detected photons to the celestial sphere
- Part V Applications of astrometry to topics in astrophysics
- 22 Galactic structure astrometry
- 23 Binary and multiple stars
- 24 Binaries: HST, Hipparcos, and Gaia
- 25 Star clusters
- 26 Solar System astrometry
- 27 Extrasolar planets
- 28 Astrometricmeasurement and cosmology
- Index
- References
22 - Galactic structure astrometry
from Part V - Applications of astrometry to topics in astrophysics
Published online by Cambridge University Press: 05 December 2012
- Frontmatter
- Contents
- List of contributors
- List of acronyms
- Preface
- Part I Astrometry in the twenty-first century
- Part II Foundations of astrometry and celestial mechanics
- Part III Observing through the atmosphere
- Part IV From detected photons to the celestial sphere
- Part V Applications of astrometry to topics in astrophysics
- 22 Galactic structure astrometry
- 23 Binary and multiple stars
- 24 Binaries: HST, Hipparcos, and Gaia
- 25 Star clusters
- 26 Solar System astrometry
- 27 Extrasolar planets
- 28 Astrometricmeasurement and cosmology
- Index
- References
Summary
Introduction
As discussed in detail in Chapter 2, two emblematic (space-based) astrometric missions to be launched in the near future, namely, Gaia and SIM Lite, will have a profound impact in many branches of astrophysics, including Galactic structure and stellar populations. It is therefore interesting to mention, first, some of the expected capabilities of these astrometric missions. In a nutshell, SIM Lite (recently deferred) will be an optical interferometer operating in an Earth-trailing solar orbit. The goal is to measure stellar positions, trigonometric parallaxes, and proper motions down to magnitude 20 with an accuracy of 4 microarcsec-onds (Has). This breakthrough in capabilities will be possible because SIM will use optical interferometry. On the other hand, the primary goal of Gaia is to investigate the origin and subsequent evolution of our Galaxy through a census of more than 109 stars (both in our Galaxy and in nearby members of the Local Group), measuring their positions with a best accuracy of 7 üas, 24 üas at magnitude 15 with decreasing accuracy to magnitude 20. Together with stellar distances and motions, this mission will allow astronomers to build the most accurate three-dimensional map to date of the stellar constituents of our Galaxy. Gaia will also perform low-spectral-resolution and photometric measurements for all objects. With an approximate launch date on late 2013, the final catalog is expected to be released by 2022.
- Type
- Chapter
- Information
- Astrometry for AstrophysicsMethods, Models, and Applications, pp. 325 - 344Publisher: Cambridge University PressPrint publication year: 2012