Context. The Milky Way bulge is the nearest galactic bulge and the most readily accessible laboratory for studies of stellar populations in spheroids based on individual stellar abundances and kinematics. These studies are challenged by the strongly variable and often large extinction on a small spatial scale. Aims. We use the Vista Variables in the Via Lactea (VVV) ESO public survey data to measure extinction values in the complete area of the Galactic bulge covered by the survey at high resolution. Methods. We derive reddening values using the method described in Paper I. This is based on measuring the mean (J − K s ) color of red clump giants in small subfields of 2 × 2 to 6 × 6 in the following bulge area:• . To determine the reddening values E(J − K s ) for each region, we measure the RC color and compare it to the (J − K s ) color of RC stars measured in Baade's Window, for which we adopt E(B − V) = 0.55. This allows us to construct a reddening map sensitive to small-scale variations minimizing the problems arising from differential extinction. Results. The significant reddening variations are clearly observed on spatial scales as small as 2 . We find good agreement between our extinction measurements and Schlegel maps in the outer bulge, but, as already stated in the literature the Schlegel maps are unreliable for regions within |b| < ∼ 6• . In the inner regions, we compare our results with maps derived from DENIS and Spitzer surveys. While we find good agreement with other studies in the corresponding overlapping regions, our extinction map is of higher quality owing to both its higher resolution and a more complete spatial coverage of the bulge. We investigate the importance of differential reddening and demonstrate the need for high spatial resolution extinction maps for detailed studies of bulge stellar populations and structure. Conclusions. We present the first extinction map covering uniformly ∼315 sq. deg. of the Milky Way bulge at high spatial resolution. We consider a 30 arcmin window at a latitude of b = −4• , which corresponds to a frequently studied low extinction window, the so-called Baade's Window, and find that its A Ks values can vary by up to 0.1 mag. Larger extinction variations are observed at lower Galactic latitudes. The extinction variations on scales of up to 2 −6 must be taken into account when analyzing the stellar populations of the Galactic bulge.

We have recently obtained a set of high-resolution images of Terzan 5 in the K and J bands by using MAD 6 , a Multi-Conjugate Adaptive Optics demonstrator instrument installed at the Very Large Telescope (VLT) of the European Southern Observatory (ESO). MAD operates at near-infrared wavelengths, thus revealing the only component of stellar radiation that can efficiently cross the thick clouds of dust obscuring the Galactic bulge. It is able to perform exceptionally good and uniform adaptive optics correction over its entire field of view (1'x1'), thus compensating for the degradation effects to the astronomical images induced by the Earth's atmosphere. In particular, we have obtained a set of K-band (2.2m) images of Terzan 5 close to the diffraction limit (Fig. 1). The sharpness and uniformity of the images yields very high quality photometry, resulting in accurate (K, JK) colour-magnitude diagram (CMD) even for the very central region of the cluster, and leading to a surprising discovery. We have detected two well-defined red horizontal branch clumps, separated in luminosity: a bright horizontal branch (BHB) at K = 12.85 and a faint horizontal branch (FHB) at K = 13.15, the latter having a bluer (JK) colour (Fig. 2).We have carefully considered whether the double horizontal branch could be spurious. It is neither due to instrumental effects ( Fig. 2), nor to differential reddening 7,8 3 (as the two horizontal branch clumps in the CMD are separated in a direction which is essentially orthogonal to the reddening vector), nor to field contamination (while field stars are expected to be almost uniformly distributed over the MAD field of view, the radial distributions of the stars belonging to the two horizontal branch clumps are significantly concentrated toward the cluster centre and are inconsistent with a uniform distribution at more than 5 level; see Fig. 3a and Supplementary Information). We have also found that the radial distributions of the two horizontal branch populations are different ( Fig. 3a): according to a Kolmogorov-Smirnov test, the BHB population is significantly (at > 3.5level) more centrally concentrated than that of the FHB. The stars belonging to the BHB are also substantially more numerous than those of the FHB near the cluster centre (that is, at distances r < 20''), becoming progressively more rare at larger radii (Fig. 3b).Once alerted to the existence of the double horizontal branch, we have also (Fig. 4a).To date, apart from a significant spread in the abundance patterns of a few light elements (such as Na and O) 1 , the chemical composition of all globular clusters in the Galaxy is known to be extremely uniform in terms of iron content, with the only exception being  Centauri 4,5 in the Galactic halo. Hence, Terzan 5 is the first stellar aggregate discovered in the Galactic bulge that has globular-cluster-like properties but also with the signatures of a much more complex star formation history.To further investigate this issue, we have performed a differential reddening correc...

Context. Several recent studies have demonstrated that the Galactic bulge hosts two components with different mean metallicities, and possibly different spatial distribution and kinematics. As a consequence, both the metallicity distribution and the radial velocity of bulge stars vary across different lines of sight. Aims. We present here the metallicity distribution function of red clump stars in 26 fields spread across a wide area of the bulge, with special emphasis on fields close to Galactic plane, at latitudes b = −2 • and b = −1 • , that have not been explored before. Methods. This paper includes new metallicities from a sample of approximately 5000 K giant stars, observed at spectral resolution R ∼ 6500, in the Calcium II Triplet region. These represent the main dataset from the GIRAFFE Inner Bulge Survey. As part of the same survey we have previously published results for a sample of approximately 600 K giant stars, at latitude b ∼ −4 • , derived from higher resolution spectra (R = 22 500). Results. The combined sample allows us to trace and characterize the metal poor and metal rich bulge populations down to the inner bulge. We present a density map for each of the two components. Contrary to expectations from previous works, we found the metal poor population to be more centrally concentrated than the metal rich one, and with a more axisymmetric spatial distribution. The metal rich population, on the other hand, is arranged in a boxy distribution, consistent with an edge-on bar. By coupling metallicities and radial velocities we show that the metal poor population has a velocity dispersion that varies rather mildly with latitude. On the contrary, the metal rich population has a low velocity dispersion far from the plane (b = −8.5 •), yet has a steeper gradient with latitude, becoming higher than the metal poor one in the innermost field (b = −1 •). Conclusions. This work provides new observational constraints on the actual chemodynamical properties of the Galactic bulge, that will help discrimination between different formation models.