Speaker: Karen Masters
Location: RAS Ordinary Meeting, Burlington House
I will discuss recent results from the Galaxy Zoo project which use visual identifications of bars in disk galaxies (provided by members of the public through the Galaxy Zoo website). In this work (Masters et al. 2011, MNRAS in press) we show that the fraction of strong (or obvious) bars in nearby disk galaxies increase dramatically as the galaxies become redder. The extreme of this population are the Galaxy Zoo red spirals (Masters et al. 2010) which are as red and passive as most ellipticals – and almost all have bars.
In this talk I will discuss the role bars have on the evolution of a disk galaxy. I will question if the bar itself can be responsible for the cessation of star formation in spirals (through it’s ability to move gas, stars and dark matter radially), or if bars are just important side effects to an external processes which turn spirals red.
Finally, I will argue (using recent results at many redshifts) that red spirals are not just an unusual subset of disk galaxies of interest as a “curiosity”, but that they represent an important evolutionary stepping stone. I will show that most disk galaxies may pass through a red spiral phase as they evolve from the blue cloud to the red sequence, and suggest that bars are intimately connected to this transformation.