"The VVV-SkZ Pipeline: How to get Automatic PSF-fitting photometry from VISTA surveys. Present status and future implementations"

Francesco MAURO (Universidad de Concepcion, Chile)

Abstract

The VVV-SkZ_pipeline is a DAOPHOT-based photometric pipeline, created to perform PSF-fitting photometry of ``VISTA Variables in the Via Lactea'' (VVV) ESO Public Survey data. The pipeline replaces the user, avoiding repetitive interaction in all the operations, retaining all of the benefits of the power and accuracy of the DAOPHOT suite. The pipeline provides an astrometric photometric catalog reliable up to more than 2 magnitudes brighter than the saturation limit, where other techniques fail. It also produces deeper and more accurate photometry. These achievements allow the VVV-SkZ pipeline to produce data well anchored to the selected standard photometric system and analyze important phenomena (i.e. TRGB, RGB slope, HB morphology, RR Lyrae), that other methods are not able to manage.

"Kinematics and chemical elements of the very metal poor Globular Cluster NGC 4372"

Nikolay KACHAROV (University of Heidelberg)

Abstract

NGC 4372 is a poorly studied, old, and very metal poor Globular Cluster (GC) located close to the Galactic disk and suffering from a severe differential reddening. It was likely dynamically stirred during its frequent crossings of the Galactic disk. Here, I will present the first ever high-resolution observations of it, taken with the FLAMES instrument at the VLT. Our sample consists of 131 unique red giant stars, confirmed cluster members. We found [Fe/H] = -2.2 ± 0.1 dex without any significant metallicity spread. We have also derived the abundances of several alpha, iron-peak and n-capture elements, as well as the p-capture element Sodium, which is crucial to assess the existence of multiple populations in this GC. I will focus on the kinematic properties of NGC 4372. Based on precise radial velocities and an analytic Plummer model, we have computed the central velocity dispersion σ0 = 4.7 ± 0.9 km/s and we also found a clear signal of systemic rotation with an amplitude v_rot = 2.0 ± 0.2 km/s. NGC 4372 has unusually high systemic rotation to velocity dispersion ratio for its metallicity, which puts it in line with other very metal poor GCs like M 15 and NGC 4590, and could bring some clues to the origin of those very low metallicity systems. Finally, we found a mild flattening of NGC 4372 in the direction of its rotation. This observation favours that the flattening is indeed caused by the systemic rotation rather than tidal interactions with the Galaxy.

"A unifying view of AGN sub-pc scale structure : pushing the limit of infrared interferometry"

Makoto KISHIMOTO (MPIFR, Bonn)

Abstract

One of the big reasons why the progress in our understanding of the AGN mass accretion process has been very slow is the absolute lack of appropriate spatial resolutions. However, long-baseline interferometry in infrared wavelengths has been breaking the ground over the last several years. First I will review the recent findings in the interferometric studies of the innermost dusty structure in AGNs both in the near- and mid-infrared using the VLTI and Keck interferometer. Based on these studies, I will show that a unifying view of the sub-pc scale structure is now emerging, where the radiation pressure on dust grains is playing a central role in forming the structure. I will also discuss the up-to-date status of our on-going software effort to push the sensitivity limits of VLTI instruments.

"Migrating stars: the true hitchhikers of the galaxy"

Juan Carlos MUNOZ (ESO, Chile)

Abstract

The spatial distribution of stars of different ages within galactic disks is often used to infer how galaxies were assembled through cosmic time. However, this requires assuming that stars have always remained at roughly the same distance from the galactic center. Interestingly, though, recent theoretical and observational results suggest that stars can actually venture quite far from their initial birth radius. This raises a critical question: is the present-day radial distribution of old stars in disks determined mainly by in-situ star formation or by radial stellar migration? I will present our latest findings on this subject, based on the Spitzer Survey of Stellar Structure in Galaxies (S4G), a large survey of more than 2300 nearby galaxies imaged at 3.6 and 4.5 microns, down to depths below 1 Msun/pc2. We provide empirical evidence that resonant interactions with bars and spiral arms can rearrange old stars even at large radii. I will also discuss our current efforts to map the distribution of molecular gas in galaxies with potential signs of migration, in order to quantify how in-situ star formation and radial migration compete to build and mold the stellar backbone of galaxies.