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ASTR 551, Majewski [SPRING 2003]. Lecture Notes

ASTR 551 (Majewski) Lecture Notes


DYNAMICAL METHODS FOR DISTANCE DETERMINATION

1. Trigonometric Parallax


2. Reduced Proper Motion Diagram


3. Moving Cluster Method - useful for large, nearby clusters of stars


4. Dynamical Parallaxes of Clusters - useful for getting MV (RR Lyrae) variables


5. Dynamical π of Binary stars













Baade-Wesselink Method Applied to Pulsational Variables (BM 7.2.1)

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GETTING MV (RR)

As a demonstration of how the various distance-gauging methods work, compare the following derived values for the absolute magnitude of RR Lyrae stars (at one fiducial metallicity).

Most common methods:

  1. Statistical parallax

  2. MS fitting/WD fitting of globulars

  3. Distance to Mag. clouds

    • SN 1987 - geometry-time delay and Baade-Wesselink method

    • MS fitting

    • Cepheids

  4. Baade-Wesselink method

Can also compare the distances to the LMC and M31 from two types of pulsational variables.


SUMMARY

Main techniques used for distance-gauging different stellar types:

Supergiants Open cluster fitting
O-A stars Open clusters, secular & stat π
F-M dwarfs Trig π, moving cluster
F-M giants Moving cluster, cluster fitting, secular & stat π
White dwarfs Trig π, binaries, cluster fitting
Cepheids, RR Lyrae Stat π, Baade-Wesselink, MS fitting to clusters



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All material copyright © 2003 Steven R. Majewski. All rights reserved. These notes are intended for the private, noncommercial use of students enrolled in Astronomy 551 at the University of Virginia.