E4N1_Nov3[1] - Some Uses of the H-R Diagram • Cluster...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Some Uses of the H-R Diagram • Cluster Fitting (more on this later) – All stars at about the same distance, so uncertainty in distance vanishes. Plot apparent brightness as if it were absolute, then slide diagram until it fits => distance determination very accurate for a whole cluster, especially if there are many stars. • Do the same thing with individual objects => “spectroscopic parallax,” but it isn’t very accurate since it is based on one object. Star Formation Star Formation Facts •Stars are constantly forming. •Hot, blue stars are relatively young. •Cool, red stars are relatively old. •Stars form from otherwise stable gas clouds. •Stars form in groups. Star Birth Where do stars form? Interstellar Dust • Tiny solid particles of interstellar dust block our view of stars on the other side of a cloud • Particles are < 1 micrometer in size and made of elements like C, O, Si, and Fe Theory of Shock-wave Triggered Star Formation Since a gas cloud is stable, something Since happens to it to cause stars to form. A shockwave compresses the cloud. shockwave As it compresses it, it fragments. As Within these fragments, stars are formed. Within Contracting Protostar A protostar emerges from a fragment. protostar As gravity continues the contraction, its temperature increases. As The fragment is like a cocoon, in that the newly forming star is The protected from external effects. Protostar growth and Development Since gas clouds are usually Since slowly rotating, a protostar forms from a rotating disk. The protostar emerges from the The center of the disk. Planets may well form from the Planets disk itself. Figure 11.4 Figure ...
View Full Document

This note was uploaded on 11/27/2011 for the course AST 301 taught by Professor Harvey during the Spring '07 term at University of Texas at Austin.

Ask a homework question - tutors are online