Introductory

Distance modulus of a Cepheid

A Cepheid variable has apparent magnitude $m = 14.2$ and, from its period-luminosity relation, absolute magnitude $M = -4.5$ . Interstellar extinction along the line of sight is $A = 0.6$ mag. How far away is the star?

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Reading resources

Material that covers the physics behind this problem.

An Introduction to Modern AstrophysicsCarroll & Ostlie
The standard reference for olympiad-level astrophysics. Chapters 1-3 cover the celestial sphere, orbits and the magnitude system.
Textbook
Introductory Astronomy and AstrophysicsZeilik & Gregory
More compact than Carroll & Ostlie, with excellent worked problems on coordinates, time and telescope optics.
Textbook
HyperPhysics. AstrophysicsGeorgia State University
Quick concept maps and formula references. Good for refreshing a relationship mid-problem.
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