Recent Issues

Pages of The Astrophysics Spectator are published as a bimonthly journal on the first and third Wednesdays of each month, excepting July and December. The current issue of the journal is the home page for this site. The most recent 12 issues of the journal, starting with the permanent page for the current home page, is listed on this page. Other issues can be found by following the links in the table to the left.

• Issue 5.08, May 5, 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.
• Issue 4.20, December 19, 2007.  This issue continues the discussion of the previous issue on open star clusters; specifically, a page is added that describes various methods for deriving the distance to an open cluster without measuring the annual parallaxes of stars within the cluster.
• Issue 4.19, December 5, 2007.  Open star clusters are discussed in this issue.  Gravitationally-bound groups of stars such as the Pleiades provide convenient collections of stars for studying stellar evolution.  The properties and uses of open star clusters are discussed on a page added this issue to the “Milky Way Galaxy” topical path.
• Issue 4.18, November 21, 2007.  Theories for the dark accretion disk orbiting the central Galactic black hole are describe in a page added with this issue of the web site.
• Issue 4.17, October 31, 2007.  The outer regions of the central Galactic black hole is expected to flow directly to the black hole.  A page is added in this issue that describes this process.