Assignment
#3: Normal Galaxies
Assigned
Oct 20 ---------Due Oct 27 2009
Return the following images from the WWW and answer the questions. Place all images in a word processor and include under each picture the URL, a brief description of the images, and answer the question listed under the image.
Questions
1. For
elliptical, spiral and irregular galaxies compare their: stellar content, gas
and dust, and star formation. (Page 656, Table 24.1)
2.What is
the meaning of the terminology standard candle (page 657)? What two
properties must standard candles have? How do you use the standard
candle to determine the distance to the object?
3. Consider
the Tully-Fisher method for determining the luminosity for some spiral
galaxies. Draw the diagram in Fig 24.11 that illustrates why the spectral lines
become wider. Why is width larger for the brighter and more massive galaxies?
(Page 658). What is the maximum distance this standard candle can be used (ref
Fig 24.12)?
4.
Return an image of the Sombrero Galaxy (spiral galaxy M104) with a brief
description.
http://antwrp.gsfc.nasa.gov/apod/ap070505.html
Since you
are observing M104 edge-on how do you know it is a spiral galaxy (Ref section
24.1)?
5.Return an image of the starburst
galaxy NGC 1569 with a brief
description.
http://hubblesite.org/newscenter/archive/releases/2008/38/image/a/
What
do astronomers speculate about the cause of the star birth.
6. Return a
picture of the spiral galaxy M100 with a brief description.
http://hubblesite.org/newscenter/archive/releases/1994/49/image/a/
Make sure
your description includes:
The distance
to M100, How the distance was
measured.
The name of
the galactic cluster in which it is located.
Why canŐt Cepheid variables
be used to measure distances farther that 25 Mpc (reference section 24.2)?