ASTR 1230 (Whittle) Lecture Notes


Topic 6. STELLAR ASTRONOMY


NGC 1818

Young star cluster NGC 1818 in the Large Magellanic Cloud (HST)


A. INTRODUCTION

Human beings have wondered about the stars for probably a million years, but only in the 20th century did we achieve a real understanding of their physical nature and their life cycles. This can fairly be said to be the main accomplishment of astronomy since 1900. We now understand the stars in almost all their essentials, and only details remain to be worked out.

The astrophysical study of the stars has provided many crucial insights:

With a small telescope, you can explore many facets of stellar evolution. In fact, much of the basic evidence on stellar astrophysics was gathered historically with quite modest telescopes. This lecture introduces these subjects.


B. PROPERTIES OF THE STARS

APPARENT BRIGHTNESSES (MAGNITUDES)

  • Here is a list of the 50 brightest stars.


    INTRINSIC BRIGHTNESSES (ABSOLUTE MAGNITUDES OR LUMINOSITIES)


    TEMPERATURES


    MASSES


    C. STELLAR EVOLUTION

    THE HERTZSPRUNG-RUSSELL DIAGRAM


    STELLAR PHYSICS


    D. STELLAR EVOLUTION IN THE SKY

    With binoculars and small telescopes you can observe many aspects of stellar evolution, including individual stars, binary stars, and star clusters. The most interesting phenomena involve the initial and final phases of stellar evolution: star birth and death.

    (1) Early phases of stellar evolution

    (2) Mid-phases of stellar evolution

    (3) Late phases of stellar evolution


    Assignment:

    Web links:


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    Last modified October 2008 by rwo

    Apparent magnitude diagram, table, HR diagram, Eagle and Orion images copyright © 2000 by Nick Strobel. Plots of stars within 50 LY copyright © by R. Powell. Color image of EM spectra and plot of evolutionary tracks copyright © 2000 Harcourt, Inc.. Nuclear reaction drawing copyright © 1999 by Mike Guidry, Univ. of Tennessee. M13 picture by Bill Keel. Color photo of Orion copyright by Bill & Sally Fletcher. Color photo of Albireo copyright by M. de Regt. Text copyright © 2000-2008 Robert W. O'Connell. All rights reserved. These notes are intended for the private, noncommercial use of students enrolled in Astronomy 130 at the University of Virginia.