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Spectra of stars of the same temperature but different atmospheric pressures have subtle differences, so spectra can be used to determine whether a star has a large radius and low atmospheric pressure (a giant star) or a small radius and high atmospheric pressure. Stellar spectra can also be used to determine the chemical composition of stars; hydrogen and helium make up most of the mass of all stars. Measurements of line shifts produced by the Doppler effect indicate the radial velocity of a star. Broadening of spectral lines by the Doppler effect is a measure of rotational velocity. A star can also show proper motion, due to the component of a star’s space velocity across the line of sight.
Berman, B. “Magnitude Cum Laude.” Astronomy (December 1998): 92. How we measure the apparent brightnesses of stars is discussed.
Dvorak, J. “The Women Who Created Modern Astronomy [including Annie Cannon].” Sky&Telescope (August 2013): 28.
Hearnshaw, J. “Origins of the Stellar Magnitude Scale.” Sky&Telescope (November 1992): 494. A good history of how we have come to have this cumbersome system is discussed.
Hirshfeld, A. “The Absolute Magnitude of Stars.” Sky&Telescope (September 1994): 35.
Kaler, J. “Stars in the Cellar: Classes Lost and Found.” Sky&Telescope (September 2000): 39. An introduction is provided for spectral types and the new classes L and T.
Kaler, J. “Origins of the Spectral Sequence.” Sky&Telescope (February 1986): 129.
Skrutskie, M. “2MASS: Unveiling the Infrared Universe.” Sky&Telescope (July 2001): 34. This article focuses on an all-sky survey at 2 microns.
Sneden, C. “Reading the Colors of the Stars.” Astronomy (April 1989): 36. This article includes a discussion of what we learn from spectroscopy.
Steffey, P. “The Truth about Star Colors.” Sky&Telescope (September 1992): 266. The color index and how the eye and film “see” colors are discussed.
Tomkins, J. “Once and Future Celestial Kings.” Sky&Telescope (April 1989): 59. Calculating the motion of stars and determining which stars were, are, and will be brightest in the sky are discussed.
Discovery of Brown Dwarfs: http://w.astro.berkeley.edu/~basri/bdwarfs/SciAm-book.pdf.
Listing of Nearby Brown Dwarfs: http://www.solstation.com/stars/pc10bd.htm.
Spectral Types of Stars: http://www.skyandtelescope.com/astronomy-equipment/the-spectral-types-of-stars/.
Stellar Velocities https://www.e-education.psu.edu/astro801/content/l4_p7.html.
Unheard Voices! The Contributions of Women to Astronomy: A Resource Guide: http://multiverse.ssl.berkeley.edu/women and http://www.astrosociety.org/education/astronomy-resource-guides/women-in-astronomy-an-introductory-resource-guide/.
When You Are Just Too Small to be a Star: https://www.youtube.com/watch?v=zXCDsb4n4KU. 2013 Public Talk on Brown Dwarfs and Planets by Dr. Gibor Basri of the University of California–Berkeley (1:32:52).
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