astrometry, post-starburst atlas, morphology

Morad, Sam, and I worked out a stellar quadrangle indexing scheme that is scale, translation, and rotation-free, in preparation for our attack on the blind astrometry problem. We think the "toy" problem of solving all SDSS astrometry will be trivial, but we might be fooling ourselves.

I started (re-) building the atlas of post-starburst galaxies in the low-redshift subsample of the NYU-VAGC today, in preparation for comparing post-starburst (spectral) and interaction (morphological) signatures.

I promised Paul Schechter that I would produce a set of images from SDSS organized by morphological type. I will use the RC3 as my basis.


post-starburst galaxies and shells

In principle, post-starburst galaxy spectral signatures (ie, A stars) last a similar time to shells (which last for tens of dynamical times), so we might find shells in post-starburst galaxies. I am starting to make pictures of all the very low redshift (for good physical resolution) galaxies in SDSS with post-starburst (nuclear) spectra. Here is one that is superimposed on the shell of a neighbor!

The post-starburst galaxy is at the center of the frame.

The last "complete" catalog of shell galaxies I can find is Malin and Carter (1983). To make a new one in SDSS would be a great service, but is perhaps beyond my patience, unless someone finds an automated shell finder (that is not fooled by spiral arms).

In other news, Alar Toomre and Milos Milosavljevic gave me more ideas for subject headings (starburst galaxies and double quasars, respectively) in my review.


shells, bibtex, outline

Today I tried to understand the simplest things about shells in ellipticals; they all appear to have been identified by eye, and there don't appear to be any good quantitative, objective measures of their abundance. Doesn't bode well for inferring an interaction rate from shells without massive work in the SDSS. I did make this picture of a shell galaxy, however:

Note that, going outwards radially, the shells alternate north-south (plausibly), as predicted by Quinn (1984). Also note the ("minor axis" according to Balcells, 1997) dust lane and "arm" of star formation, strongly suggesting that the event which caused the shells also included fuel for star formation.

I also worked out a bibtex style file that does somewhat apj-like citation in text, but makes an annotated bibliography with displayed article titles, abstracts ("abstract" in the ".bib" file), and annotations ("note" in the ".bib" file). This hacked up bibtex style file is available on today's research page. Also under NYU CCPP CVS in "hoggreview/accretion".

Finally, I outlined my review. It is not ready for prime time by any means.