We present a general overview and the first results of the SUMO project (a SUrvey of Multiple pOpulations in Globular Clusters). The objective of this survey is the study of multiple stellar populations in the largest sample of globular clusters homogeneously analysed to date. To this aim we obtained high signal-to-noise (S/N>50) photometry for main sequence stars with mass down to ∼0.5 M odot in a large sample of clusters using both archival and proprietary U, B, V, and I data from ground-based telescopes. In this paper, we focus on the occurrence of multiple stellar populations in twenty three clusters. We have defined a new photometric index c U,B,I = (U − B) − (B − I), that turns out to be very effective for identifying multiple sequences along the red giant branch (RGB). We found that in the V-c U,B,I diagram all clusters presented in this paper show broadened or multimodal RGBs, with the presence of two or more components. We found a direct connection with the chemical properties of different sequences, that display different abundances of light elements (O, Na, C, N, and Al). The c U,B,I index is also a powerful tool to identify distinct sequences of stars along the horizontal branch and, for the first time in the case of NGC 104 (47 Tuc), along the asymptotic giant branch. Our results demonstrate that i) the presence of more than two stellar populations is a common feature amongst globular clusters, as already highlighted in previous work; ii) multiple sequences with different chemical contents can be easily identified by using standard Johnson photometry obtained with ground-based facilities; iii) in the study of GC multiple stellar populations the c U,B,I index is alternative to spectroscopy, and has the advantage of larger statistics. ⋆ Based on observations made with the INT telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. Based on observations made with MPG/ESO 2.2m telescope in La Silla, Chile, proposal 088.A-9012.†

Open Clusters have long been used to study the chemo-dynamical evolution of the Galactic disk. This requires an homogeneously analysed sample covering a wide range of ages and distances. In this paper we present the OCCASO second data release. This comprises a sample of high-resolution (R > 65, 000) and high signal-to-noise spectra of 115 Red Clump stars in 18 Open Clusters. We derive atmospheric parameters (T eff , log g, ξ), and [Fe/H] abundances using two analysis techniques: equivalent widths and spectral synthesis. A detailed comparison and a critical review of the results of the two methods are made. Both methods are carefully tested between them, with the Gaia FGK Benchmark stars, and with an extensive sample of literature values. We perform a membership study using radial velocities and the resulting abundances. Finally, we compare our results with a chemo-dynamical model of the Milky Way thin disk concluding that the oldest Open Clusters are consistent with the models only when dynamical effects are taken into account. 65 HERMES 5147 ± 46 2.98 ± 0.07 1.15 ± 0.06 5106 ± 12 2.85 ± 0.04 1.43 ± 0.02 5126 29 28 2.92 0.06 0.09 0.08 ± 0.04 −0.02 ± 0.05 0.05 W119 18:28:17.64 +06:46:00.1 8.95 67 FIES 5138 ± 42 2.84 ± 0.06 1.28 ± 0.06 5203 ± 21 3.02 ± 0.04 1.47 ± 0.03 5170 31 46 2.93 0.05 0.13 0.03 ± 0.05 −0.02 ± 0.05 0.02 70 HERMES 5192 ± 56 3.03 ± 0.07 1.09 ± 0.05 5218 ± 18 3.08 ± 0.04 1.44 ± 0.02 5205 37 18 3.06 0.06 0.04 0.03 ± 0.04 −0.07 ± 0.05 0.05 W126 18:28:22.97 +06:42:29.3 8.77 95 FIES 5054 ± 50 2.55 ± 0.06 1.28 ± 0.09 5131 ± 12 2.80 ± 0.04 1.53 ± 0.02 5092 31 54 2.68 0.05 0.18 −0.01 ± 0.05 −0.04 ± 0.05 0.02 78 HERMES 5190 ± 37 3.07 ± 0.09 1.23 ± 0.05 5174 ± 12 2.92 ± 0.03 1.44 ± 0.02 5182 24

Aims. XO-2 is the first confirmed wide stellar binary system where the almost twin components XO-2N and XO-2S have planets, and it is a peculiar laboratory in which to investigate the diversity of planetary systems. This stimulated a detailed characterization study of the stellar and planetary components based on new observations. Methods. We collected high-resolution spectra with the HARPS-N spectrograph and multi-band light curves. Spectral analysis led to an accurate determination of the stellar atmospheric parameters and characterization of the stellar activity, and high-precision radial velocities of XO-2N were measured. We collected 14 transit light curves of XO-2Nb used to improve the transit parameters. Photometry provided accurate magnitude differences between the stars and a measure of their rotation periods. Results. The iron abundance of XO-2N was found to be +0.054 dex greater, within more than 3σ, than that of XO-2S. The existence of a longterm variation in the radial velocities of XO-2N is confirmed, and we detected a turnover with respect to previous measurements. We suggest the presence of a second massive companion in an outer orbit or the stellar activity cycle as possible causes of the observed acceleration. The latter explanation seems more plausible with the present dataset. We obtained an accurate value of the projected spin-orbit angle for the XO-2N system (λ = 7• ± 11 • ), and estimated the real 3D spin-orbit angle (ψ = 27 +12 −27 degrees). We measured the XO-2 rotation periods, and found a value of P = 41.6 ± 1.1 days in the case of XO-2N, in excellent agreement with the predictions. The period of XO-2S appears shorter, with an ambiguity between 26 and 34.5 days that we cannot solve with the present dataset alone. The analysis of the stellar activity shows that XO-2N appears to be more active than the companion, perhaps because we sampled different phases of their activity cycle, or because of an interaction between XO-2N and its hot Jupiter that we could not confirm.