The Galaxy Evolution Years ( ) Pioneered instrumental and observing techniques to measure the right kind of stuff for galaxies.

Common Theme: Evolution of Forms Evolution of the land: subtleties of change in the desert landscape Evolution of circumstellar material: from crud to planets Evolution of Galaxies: from empty darkness to physical forms

Bothun-Strom Connection One of his early papers stole my thesis title Establishing a connection was initially difficult Found common ground in 1982 Hermann and the Blue Toad Misery Club St. Louis Cardinals Teaching at Amherst and softball ringer(1983)

We Start in 1976 Photographic detectors predominate  issues of photometric calibration are rampant; Galaxy morphology is different on non-linear compared to linear detectorsPhotographic detectors predominate  issues of photometric calibration are rampant; Galaxy morphology is different on non-linear compared to linear detectors The Hubble Sequence: Physical, Transformative or TransientThe Hubble Sequence: Physical, Transformative or Transient Density wave theory was popular  widely thought to adequately account for observed morphologiesDensity wave theory was popular  widely thought to adequately account for observed morphologies

Continuing The Universe in 1976 The extensive nature of the dark matter component in galaxies was unknownThe extensive nature of the dark matter component in galaxies was unknown There were no known massive low surface brightness galaxiesThere were no known massive low surface brightness galaxies The complex nature of the hierarchical clustering of galaxies was not even imagined by anyone.The complex nature of the hierarchical clustering of galaxies was not even imagined by anyone. Aperture photometry dominates our measurements of galaxies (hard work).Aperture photometry dominates our measurements of galaxies (hard work).

Properties of Galaxies –what can be measured? Shape, structure (surface photometry), morphology Stellar populations – young (optical), old (infrared) Dynamics – rotation curves Bulge/Halo properties Abundance gradients (as related to density waves)

The Strom’s Legacy Were really the first to systematically probe and integrate the various measurable properties of galaxies so that some coherent theory might arise This approach influenced other “young” researchers at the time to enjoy the thrills of constant data overload

Legacy Chronology  Initial focus is on Abundance Gradients

Next: Integration of Wavelengths This approach would prove to be a hallmark of Strom’s work and remember, detectors sucked back then. This approach would prove to be a hallmark of Strom’s work and remember, detectors sucked back then. This work was substantial and would allow for the structure of disk galaxies to be looked at in a new way This work was substantial and would allow for the structure of disk galaxies to be looked at in a new way

Next: Integration of Dynamics and Environmental Influences To help understand variation in spiral arm strength/definition and prevalence of smooth arm spirals in clusters

Next: Size Matters  A prophetic statement: “… the true sizes of spiral galaxies must be considerably larger than currently believed”

Next: Pundit Time After a mere 3 years of this effort:

And Just when you have it all figured out and wrote a review Something unexpected comes along:

And then its time to move on  Perhaps its coincidental, but one can’t help wonder if the first author of this last paper helped drive this change in direction

So Where are we Today  Galaxies Look Prettier

Today  Massive LSB galaxies are known to exist (but, alas, they are not very pretty and are mostly just noise)

Today  Baryon’s don’t matter

Today  Galaxies are clustered in far more complex ways than anyone could ever have imagined.  Encounters/environmental influence is likely therefore larger

But what do we know Today?  Why is the Baryonic mass fraction of galaxies nearly constant? (Cortese etal 2008)  Why don’t galaxies have hard edges if star formation is density driven? (XUV disks)  Why is the Galactic Halo still being formed from stars streaming in? (SDSS new LG members)  What determines how many stars form in the first generation and how much material is left over (similar to planetary disk phenomena)  How does galaxy assembly really work?

Summary So galaxy formation evolution, like planet formation, has gotten a lot more complicated. New data simply reminds us of all that we do not know. So galaxy formation evolution, like planet formation, has gotten a lot more complicated. New data simply reminds us of all that we do not know. Strom’s legacy as an astronomer lies in commitment to leverage all wavelengths to get a fully integrated physical view of the system. This how all of astronomy should be done. Strom’s legacy as an astronomer lies in commitment to leverage all wavelengths to get a fully integrated physical view of the system. This how all of astronomy should be done.