Nature vs. nurture in the evolution of galaxies is not completely understood. Where a galaxy is found, its environment, can play an important role in determining the properties of that galaxy. This may not always be true, however.
In this article, the authors measure the stellar mass-metallicity relation for star forming galaxies ranging to z~2.3. They find that mass-metallicity relationship for these galaxies evolves with time and also that it flattens at late times.
Type Ia Supernovae are extensively used in astronomy research, but the progenitors of these massive explosions are still not well understood. This paper discusses new evidence that there are two distinct populations of type Ia supernovae, and that they originate from different stellar populations.
“Galactic archaeology” is the term that has come to refer to using the motions and chemical compositions of stars of different ages to learn about the history of the Milky Way. It seems to me that “galactic paleontology” might be a bit more accurate. I hope to see galactic archaeology v. galactic paleontology fought out in the comments!
In this paper, the SLUGGS team explores an alternate way to determine the metallicity of a globular cluster based on the calcium triplet rather than color. Previous studies have shown what appear to be two peaks in the metallicity of the population of globular clusters surrounding early-type galaxies – a bimodal distribution – but some astronomers have pointed out that the way we measure metallicity in globular clusters can make a unimodal distribution in metallicity appear as a bimodal one. The SLUGGS team recalibrates the calcium triplet relation and surveys 903 clusters around 11 galaxies, and finds a similar bimodal distribution, implying that most massive galaxies undergo at least two star formation episodes.