Fundamentals of Astronomy

Cesare Barbieri, Ivano Bertini

• Publisher: CRC Press
• Year: 2020
• ISBN:
  9781000223804
• Edition: 2
• Topic: Sciences physiques
• Subtopic: Astronomie et astrophysique

Providing a broad overview of foundational concepts, this second edition of Fundamentals of Astronomy covers topics ranging from spherical astronomy to reference systems, and celestial mechanics to astronomical photometry and spectroscopy.

It expounds arguments of classical astronomy that provided the foundation for modern astrometry, whilst presenting the latest results of the very-long-baseline interferometry (VLBI) radio technique, optical interferometers and satellites such as Hipparcos and GAIA, and recent resolutions of the IAU and IERS regarding precession, forced and free nutation, and Earth figure and rotation.

Concepts of general relativity are explored, such as the advance of Mercury's perihelion, light deflection and black holes, in addition to the physical properties, orbits, and ephemerides of planets, comets and asteroids with an extension to visual binary stars orbital reconstruction. Extrasolar planets are also discussed, with reference to radial velocity and transits measurements by ground and space telescopes.

Basic concepts of astronomical photometry, spectroscopy and polarimetry are given, including the influence of the terrestrial atmosphere. Classical works, such as Hipparchus, are mentioned in order to provide a flavor of the historical development of the field.

It is an ideal textbook for undergraduate and graduate students studying astronomy, astrophysics, mathematics, and engineering. Supplementary and explanatory notes provide readers with references to additional material published in other literature and scientific journals, whilst solved and unsolved exercises allow students to review their understanding of the material.

Features:

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• Provides an introductory vision of arguments from spherical astronomy to celestial mechanics to astronomical photometry and spectroscopy

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• Presents the information at an introductory level without sacrificing scientific rigor

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• Fully updated throughout with the latest results in the field

1 Spherical Astronomy

The name spherical astronomy indicates the systematic and formal representation of the positions and angular movements (motions) projected on the celestial sphere of the heavenly bodies. The name astrometry indicates the several methods of measurement and data reduction. When the distances of these bodies are known, their position in the Cartesian space, velocities and accelerations can be determined. Celestial mechanics, which one may also call dynamical astronomy when extended from Solar System objects to stars and galaxies, utilizes positions, motions, acceleration and masses to determine the forces responsible for the observed orbits and calculate the past and future ones. At a higher level of investigation, the shape, inner structure and rotation of the celestial bodies will be taken into account, but at the moment, we proceed as if the planets or comets or stars are geometrical points.

In this chapter, we begin the study of spherical astronomy, using essentially geometric concepts, without considering the physical bases of the phenomena. Historically, this is the way astronomy began several millennia ago, leading to the geocentric conception of the world that found its maximum expression in the Ptolemaic theory. Such vision prevailed until Nicolaus Copernicus put forward his heliocentric model of the Solar System (De revolutionibus orbium coelestium, 1543). The geocentric vision was finally abandoned after the discoveries made by Galileo Galilei in the early 17th century. At any rate, this geocentric vision is fully adequate for the present purposes. In subsequent chapters, when investigating the dynamics of planets, asteroids, comets or finally the movements of the stars with respect to the Sun and to the entire Milky Way, we will be led to the operational definition of reference frames which are as inertial as possible, in order to correctly apply the Newtonian dynamical laws. Occasionally, we will discuss the inadequacies of the Newtonian theory and introduce some concepts of general relativity.

The following sections will provide notions of plane and spherical trigonometry needed in the rest of the book.

1.1 Elements of Plane Trigonometry

In theoretical expressions, such as the trigonometric functions, the angles on a plane must be expressed in radians. However, the practical units of sexagesimal degrees (360 degrees in the circle, symbol °; minutes of arc, symbol ′, 1° = 60′; seconds of arc, symbol ″, 1′ = 60″) are employed in s...