Problem set 2 for ASTR 323/423: The Local Universe
Due in class, Tues Feb 4.
Individual problems:
(1) Galaxy classification
Get your hand in by going to the Galaxy
Zoo website.
Read The Story So Far
and then follow the Classify link and
click on Examples to see what they want you to do.
(2) Sandage "The Hubble Atlas of Galaxies" pp 7-26 gives a detailed
description of the traditional Hubble classification. Using this as a
guide, and using galaxy images from the Sloan Digital Sky Survey, this
time using the Navigator function (
http://skyserver.sdss3.org/dr8/en/tools/chart/navi.asp; type in RA and Dec
in degrees in the window), decide the Hubble classification of the
following galaxies, print out an image to hand in, and write a short
paragraph explaining why you chose this classification which will
include which galaxies in the Hubble atlas are similar. Note any
difficulties you had applying Sandage's rules.
RA=221.546, Dec=-0.223
Each undergrad student will give a short presentation in class justifying your
classification.
(3)
Groups:
Morphological classification can only get us so far, and is
particularly difficult to implement for "look back" studies of high
redshift galaxies. Find a recent paper (after 2000) which describes
the measurement of one of the following galaxy properties: color, star
formation rate, metallicity. Explain how the measurement is made (do
you need spectra or only imaging? etc), what are sources of random and
systematic error, and give a critical appraisal of this technique as
(i) a way of classifying galaxies and (ii) a way of constraining their
formation and/or evolution. Run your chosen paper past Prof Morrison
first.
Note that you may be given either regular optical photometry (SDSS) or
IR (UKIDSS); make note of what you get since you would not expect to
see the same features in the optical and IR.
Classify 15 galaxies and print out the summary you get by clicking the
Profile tab.
Note: all students classify all galaxies, each undergrad student gives a
presentation on one galaxy.
RA=145.514, Dec=0.336
RA=39.849, Dec=1.094
RA=36.907, Dec=-1.155
RA=152.1104, Dec=12.3
RA=161.957, Dec=12.582
Another galaxy of your choice near one of these galaxies. Give RA and
Dec and print out a color image.