Properties of Stars (continued)

Reading: Chapters 19 (The Nature of Stars) and 5 (The Nature of Light)

Normal Stars

Mass = 0.08 to ~50-100 times the mass of the Sun
Radius = 0.1 to ~1,000 times the radius of the Sun
Surface Temperature = 2,500 Kelvins to 50,000-100,000 Kelvins
Luminosity = 0.0001 to 100,000 times the luminosity of the Sun

Note that the above numbers are given in terms of the properties of the Sun. In physical units, the properties of the Sun are:

Mass = 2.0x10**30 kilograms
Radius = 696,000 kilometers
Surface Temperature = 5,800 Kelvins
Luminosity = 3.9x10**26 Watts

The properties of normal stars span rather narrow ranges except for their luminosities. We will also point out later, that there are several well-defined relationships between the various stellar properties which hold clues as to their internal structures. In this class, we will worry about:

how these numbers were determined
why the above numbers are what they are (and how they are related)

Let us now consider these topics We will first address how we know things about the Sun and then generalize to other stars. We will discuss:

the Astronomical Unit and how it is determined
the determination of the solar radius
the determination of the solar luminosity
the determination of the solar mass
the determination of the solar surface temperature and, as a related issue, the Spectral Classification of stars

After these topics, we will address ways in which the general properties of stars represented which yield clues to the fundamental nature of stars (e.g., the Hertzsprung-Russell, the Mass-Luminosity Rewlationship, ... )