Read on Twitter
Yet another paper of the #TIMERsurvey: This time we use @ESO #MUSE data to derive mean stellar population properties of the three inner bars in the TIMER sample, compare them to the properties of main bars, and constrain their dynamical structure!
https://arxiv.org/abs/2012.04661
https://arxiv.org/abs/2012.04661
Yes, you read right! There are indeed disc galaxies that host two bars at the same time: A main bar in the main disc and a smaller, inner bar located in the nuclear disc. Although main bars are well-studied structures, the nature of inner bars still remains debated.
We find that inner bars are clearly distinguished from their surroundings, in particular by their elevated metallicities and depleted [a/Fe] abundances. And in fact, in such maps of mean population properties inner and main bars look very similar.
![We find that inner bars are clearly distinguished from their surroundings, in particular by their elevated metallicities and depleted [a/Fe] abundances. And in fact, in such maps of mean population properties inner and main bars look very similar.](https://pbs.twimg.com/media/Eo3oWjsXMAAViGu.png "We find that inner bars are clearly distinguished from their surroundings, in particular by their elevated metallicities and depleted [a/Fe] abundances. And in fact, in such maps of mean population properties inner and main bars look very similar.")
In addition, the ends of inner bars appear to have younger stellar populations, an effect known from main bars as orbital age separation, suggesting that the youngest populations, i.e. those with the lowest velocity dispersion, occupy the most elongated orbits along the bar.
We also have a look at the radial population profiles along and perpendicular to inner bars. Metallicity and [a/Fe] profiles are flat along the inner bar major axis while the minor axis profiles are more similar to those observed in nuclear discs. This effect of radial mixing
is also known from main bars, and suggests that both main and inner bars significantly affect the distribution of stars in the nuclear discs. This is consistent with inner bars being built by stars on strongly elongated orbits, analogous to the x1 orbits in main bars.
In summary, inner bars appear to be dynamically very similar to the main bars of disc galaxies, differing only on the spatial scale on which they form and evolve.
And if you find this exciting and want to see more in the future, you could also hire me!
And if you find this exciting and want to see more in the future, you could also hire me!
