The Fornax Cluster VLT Spectroscopic Survey. I – VIMOS spectroscopy of compact stellar systems in the Fornax core region

We present the results of a wide spectroscopic survey aimed at detecting extragalactic globular clusters (GCs) in the core of the Fornax cluster. About 4500 low resolution spectra (from 4800 to 10000 Å) were observed in 25 VLT/VIMOS masks covering the central 1 deg2 around the dominant galaxy NGC 1399 corresponding to ∼175 kpc galactocentric radius. We describe the methodology used for data reduction and data analysis. We found a total of 387 unique physical objects (372 GCs and 15 ultra compact dwarfs) in the field covered by our observations. Most of these objects lie in the region of NGC1399 halo, with only 10% likely belonging to other giant galaxies 48 of these objects have a literature counterpart. The new VIMOS dataset is complementary to the many GC catalogues already present in the literature and it brings the total number of tracer particles around NGC 1399 to more than 1130 objects. With this comprehensive radial velocity sample we have found that the velocity dispersion of the GC population (equally for red and blue GC populations) shows a relatively sharp increase from low velocity dispersion (∼250 − 350 km s$−1$) to high velocity dispersion (∼300 − 400 km s$−1$) at projected radius of ≈10 arcmin (∼60 kpc) from the galaxy centre. This suggests that at a projected radius of ≈60 kpc both blue and red GC populations begin to be governed by the dominating Fornax cluster potential, rather than by the central NGC 1399 galaxy potential. This kinematic evidence corroborates similar results found using surface brightness analysis and planetary nebulae kinematics

Extending the evolution of the stellar mass-size relation at z < 2 to low stellar mass galaxies from HFF and CANDELS

Galaxie

A Deep View into the Nucleus of the Sagittarius Dwarf Spheroidal Galaxy with MUSE. I. Data and Stellar Population Characterization

The center of the Sagittarius dwarf spheroidal galaxy (Sgr dSph) hosts a nuclear star cluster (NSC), M54, which is the only galaxy nucleus that can be resolved into individual stars at optical wavelengths. It is thus a key target for understanding the formation of NSCs and their relation to globular clusters (GCs). We present a large Multi-Unit Spectroscopic Explorer data set that covers M54 out to ~2.5 half-light radius, from which we extracted the spectra of ~6600 cluster member stars. We use these data in combination with Hubble Space Telescope photometry to derive age and metallicity for each star. The stellar populations show a well-defined age–metallicity relation, implying an extended formation history for the central region of Sgr dSph. We classify these populations into three groups, all with the same systemic velocity: young metal-rich (YMR; 2.2 Gyr, [Fe/H] = −0.04); intermediate-age metal-rich (IMR; 4.3 Gyr, [Fe/H] = −0.29); and old metal-poor (OMP; 12.2 Gyr, [Fe/H] = −1.41). The YMR and OMP populations are more centrally concentrated than the IMR population, which are likely stars of the Sgr dSph. We suggest that the OMP population is the result of accretion and merging of two or more old and metal-poor GCs dragged to the center by dynamical friction. The YMR is consistent with being formed by in situ star formation in the nucleus. The ages of the YMR population suggest that it may have been triggered into forming when the Sgr dSph began losing its gas during the most recent interaction with the Milky Way, ~3 Gyr ago

Variance optimal hedging in the Black-Scholes model for a given number of transactions

Theme 4 - Simulation et optimisation de systemes complexes - Projet MATHFISIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : 14802 E, issue : a.1999 n.3767 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc