Problem set 2 for ASTR 323/423: The Local Universe

Due in class, Tues Feb 4.

Individual problems:

(1) Galaxy classification

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.
Note: all students classify all galaxies, each undergrad student gives a presentation on one galaxy.

(a) RA=221.546, Dec=-0.223
(b) RA=145.514, Dec=0.336
(c) RA=39.849, Dec=1.094
(d) RA=36.907, Dec=-1.155
(e) RA=152.1104, Dec=12.3
(f) 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.

Each student will give a short presentation in class justifying your classification.

(2)

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.