PROBLEM SET #3

ASTR 3730

 

1. A star is determined (by parallax) to be 5pc away. It has a blackbody spectrum which peaks at 2900. At Earth the flux from this star is measured to be 10-9 ergs/cm 2 /s .
a) What is its temperature?
b) What is its radius?
c) What kind of star is it?

2. A star is measured to have a spectrum given by:

wpe2.gif (1843 bytes) ergs/cm2/s/Hz

a) What is the temperature of the star?
b) Assuming it is 3000pc away, what is its radius?
c) What kind of star is it?

3.

 

An active galaxy looks like a star with temperature 5000K surrounded by an electron cloud with all electrons having g = 103

a) Into what part of the spectrum would one expect to see the galaxy starlight scattered?
b) With B=10-5 gauss in the cloud, in what part of the spectrum is the synchrotron radiation to be found?
c) Can we untangle such a spectrum?