Anyways - while the interpretationis interesting, I think these papers are wrong. They are not doing a careful job with the analysis which is leading the field astray - well may be not astray but it would be nice to see better analysis of these data which will put this “exciting” discovery to rest

Tiny massive galaxies: It seems a problem if these things are actually that massive. However, even without that high-profile result, if you crank down the mass and accept all their other characteristics, if they are truly quiescent, they are somewhat surprising as very small-radius objects in which star formation has quenched very early. I’ll claim (although I’m open to correction) that there are few or no obvious direct descendants of such objects in the local universe either (there are lots of small galaxies like dwarf ellipticals, but I don’t believe those are old enough). So you would have to merge them away or subsequently add stars around them (to make them cores of bigger old galaxies, or bulges). Or they’re not really quiescent. All of those are possible, it remains to be seen which, if any, are believable.

specifically, I had no idea that C/O ratios changed so much as starts evolved- I thought they were either C stars or O stars as a result of initial composition. Very cool.

Just one more totally unrelated question:
I was reading (and blogging about) a geochemistry paper that used isotopic constraints to suggest that the solar system-generating supernova was a Type II with a neutrino-driven wind.

What is a neutrino-driven wind, and how can particles that pass through everything drive?

Very interesting. Regarding M/L, wouldn’t stellar metallicity be a factor ? That is
since these stars are on the whole more likely to be metal deficient then their present day counteraprts, then I would think that this could affect the stellar luminosity and give a different M/L then if we assumed a solar-type metallicity.
If I recall correctly, metal deficiency tend to make a star bluer and brighter.

So, some, but not all, RGB stars will become AGB stars. The inert core doesn’t have sufficient pressure support to hold it up against gravity, so it collapses continuously, becoming denser and hotter as it does so. In higher mass stars, the density and temperature get hot enough that the Helium can start fusing into Carbon. In lower mass stars, the collapsing core never quite makes it, and fusion in the core is over.

Also, which star creates S-process nuclides, the AGB or the RGB (I seem to recall that there was a carbon-burning step required for n production, so I’m going to assume whatever the next step up from AGB is)?

Do RGB’s turn into AGB’s when the core gets big enough to fuse?

-the geochemist who occasionally wonders where all these isotopes (and pre-solar grains) come from

And I don’t think that failure to know these differences is qualification for idiothood!!!! (Especially for someone who knows the proper distinction between physics and chemistry

The typical ages that Mariska finds for these galaxies is 0.5 Gyr, which is pretty young, and the M/L values are pretty small as a consequence, typically 1 or smaller.

These things are really weird. Some colleagues and I are looking for similar weird objects but with a much more robust determination of the mass. This could lead to some interesting results.

Something else I wanted to discuss is you spelling of Dutch names. Pieter is the equivalent of and pronounced similarly as Peter, but Peiter would be pronounced as Pighter (so lighter with a P), which would be an uncommon name. The same holds for Kreik; Mariska her surname is Kriek. So this should make it easier for you to correct all my spelling mistakes in English the next time I ask for feedback from you for one of my papers…