h1s - Homework 1 Solutions 1 Show that an extinction of A ...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

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

Unformatted text preview: Homework # 1 Solutions 1. Show that an extinction of A λ = 1 magnitude leads to a flux F λ decrease to 40% of its original value. 1 magnitude is equivalent to a reduction of intensity of 10 − 2 / 5 = 0 . 398. 2. Assuming dust grains are 0 . 1 μ m in radius, that the gas density in the ISM is n H = 1 cm − 3 , and the number density of dust grains is n d = 10 − 12 cm − 3 and uniformly distributed, find the column density N H of hydrogen to be expected along a line of sight in which a source is observed to have an extinction A V = 1 magnitude. What is the mean free path of light along this line of sight? What is the distance to the source? The mean free path ℓ = ( nσ ) − 1 where n is the number density of scatter- ers/absorbers and σ is the effective cross section. For dust interacting with light which has a wavelength smaller than the dust size, the effective cross section is πr 2 d . Then ℓ = 1 n d πr 2 d ≃ 1 . 001 kpc ....
View Full Document

This note was uploaded on 01/25/2012 for the course AST 346 taught by Professor Lattimer during the Spring '11 term at SUNY Stony Brook.

Page1 / 2

h1s - Homework 1 Solutions 1 Show that an extinction of A ...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online