Issues of 2008
This page lists the home pages for this web site for the year 2008. These
pages constitute volume 5 of The Astrophysics Spectator.
- Issue 5.18, November 19, 2008. This issue, the last of 2008, adds the “Degenerate Objects” topical path to the web site. This path is comprised of articles on brown dwarfs, white dwarfs, and neutron stars that were previously under the “Stars” topical path.
- Issue 5.17, October 29, 2008. Objects as different as Saturn and the white dwarf Sirius B are fundamentally the same. Two pages added in this issue describe the role of degeneracy pressure in supporting both Saturn and the white dwarfs against the force of gravity. The first page describes what degeneracy pressure is, and the second page describes the limits on the mass of a degenerate object and their connection to several fundamental constants of nature.
- Issue 5.16, October 10, 2008. A page added in this issue to “The Structure of the Universe” topical path explains the characteristic sizes of the stars and the planets. A commentary added in the issue describes a peculiar, non-physical design for a rocket engine.
- Issue 5.15, September 17, 2008. The brown dwarf has a structure set by degeneracy pressure and an evolution set by its mass. These are discussed in a page added to the “Stars” topical path in this issue. A commentary added with this issue discusses the unwarranted worries about the new Large Hadron Collider at CERN.
- Issue 5.14, September 5, 2008. The brown dwarf, a body too light to initiate hydrogen thermonuclear fusion, is the topic of this issue. The commentary for this issue is on the overinterpretation of the current minimum in the solar sunspot cycle.
- Issue 5.13, August 15, 2008. This issue adds a page on how stars are classified by the pattern of lines their their spectra.
- Issue 5.12, August 1, 2008. Astronomers measure the brightness and color of a star in units of magnitude. The origin and meaning of this measure is detailed in a page added to the “Observational Astronomy” topical path in this issue.
- Issue 5.11, July 16, 2008. In this issue, a page is added that shows the nearest stars plotted on an HR diagram shows . This diagram shows the stars on the dark end of the main sequence and the degenerate dwarfs. A second page added with this issue lists the 10 brightest stars of the sky that are within 10 parsecs of the Sun.
- Issue 5.10, June 6, 2008. The open clusters and the globular clusters give us insight into how stars change over billions of years. This is discussed in a page added in this issue of the web site.
- Issue 5.09, May 21, 2008. A fundamental bit of evidence for the nature of stars is provided by the Hertzsprung-Russell diagram. This diagram shows that there are fundamentally two types of stars, one powered by hydrogen and the other powered by helium. A page showing the properties of the Hertzsprung-Russell diagram and their interpretation is added to the “Stars” path with this issue.
- Issue 5.08, May 7, 2008. At the beginning of its life, a star is powered purely by its own self-gravity. Such a star is called a protostar. The page added to the web site with this issue discusses the structure and evolution of the protostar.
- Issue 5.07, April 18, 2008. The birth of binary stars is the subject of a page added with this issue.
- Issue 5.06, April 4, 2008. This issue continues the discussion of binary star systems with a page on the “Stars” topical path that describes the basic properties of binary stars.
- Issue 5.05, March 19, 2008. A page is added to the “Stars” topical path that describes how the masses of stars in a binary system are derived.
- Issue 5.04, February 29, 2008. A page is added to the Milky Way Galaxy path that describes how the mass density of the local Galactic disk is measured.
- Issue 5.03, February 18, 2008. Molecular clouds collapse to form stars, but how this collapse occurs is not settled in the scientific community. This update of the web site adds a page that describes the two theories for the gravitational collapse of molecular clouds. A page discussing the Jeans length is also updated in this issue.
- Issue 5.02, January 30, 2008.
Stars are born in the collapse of molecular clouds. This issue adds to the web site a page that describes the molecular cloud and a page that describes the Jeans length and mass, which give the natural size of a gravitationally-bound system.
- Issue 5.01, January 16, 2008.
This first issue of the year adds two pages to the web site that describe the material that fills the space between the stars. The first page is an introduction to the interstellar medium. The second page describes why the interstellar medium is segregated into cool, dense clouds surrounded by warm, tenuous gas.