Massive Stars in the SDSS-IV/APOGEE2 Survey. New OB and Yellow Supergiant Stars in the Direction of Sagittarius and Perseus Spiral Arms

book Aldo Mura-Guzmán The Australian National University Fluorine in different stellar populations The processes involved in the production of Fluorine are still unclear and under debate, since the theoretical models do not well reproduce the observations. The only currently confirmed site of F production, asymptotic giant branch (AGB) stars, is not certain to be responsible for the cosmic abundance. Moreover, an intriguing difference in F abundances has been found between Globular Clusters (GCs) and field stars, where field stars show higher amounts of F by a factor of 10 compared to GCs. This difference could reflect the impact of the environment upon nucleosynthesis, i.e., metallicity dependent yields of fluorine which would help establish the nucleosynthetic origin. This work presents Fluorine abundances corresponding to Carbon Enhanced Metal-Poor stars, field stars from the thin and thick disk, Sagittarius stream stars and 4 Globular Clusters covering a wide range of metallicities ([Fe/H] < -2 for CEMP stars; -1.0 < [Fe/H] < 0.3 for field stars + Sagittarius; -1.0 < [Fe/H] < 0.0 for GCs). Using high-resolution spectra from PHOENIX, CRIRES and IGRINS, Fluorine abundances were measured from the 2.3 μm HF molecular line by spectrum-synthesis method. Observations are here compared with state-of-the-art theoretical predictions which include contributions from the different proposed sites of production (i.e. SNeII, ABG stars, W-R stars, &c.), and previous abundance determinations from literature. All this allows establishing a thorough observational framework in order to better understand the formation sites of Fluorine, its yield dependency and its nucleosynthesis in the Milky Way galaxy. Alex Alarcón Universidad de Concepción Kemochinematical tracers for the formation of dSph Leo I vs Simulations Numerical simulations have shown that the Dissolving Star Cluster Model, i.e. many star clusters spreading their stars inside a single dark matter halo, building up the luminous component, is able to explain all dynamical and structural features of dwarf spheroidal galaxies. The main prediction of this model is the presence of stellar streams from stars originating in the same star cluster. We are applying BEACON both to simulations and observational data of 942 stars from Leo I, to find to find chemo-kinematic patterns among stars of different stellar populations using their metallicity and radial velocity. We present the presence of 13 possible streams in the Leo I data with projected angular momentum vectors distributed in random directions.The results are in perfect agreement with the dissolving star cluster model. It is necessary to apply this method to more galaxies with a high quantity of high resolution spectra to have a better understanding of the formation of these objects. Alexandre Roman Lopes ULS Massive Stars in the SDSS-IV/APOGEE2 Survey. New OB and Yellow Supergiant Stars in the Direction of Sagittarius and Perseus Spiral Arms We have developed a semi-empirical spectral analysis applied in the ongoing massive star survey conducted by the Sloan Digital Sky Survey (SDSS)-IV/ Massive Star Team. A large sample of new Oand B-type stars (among several Yellow supergiants) were identified along the Sagittarius and perseus spiral arms, using the APOGEE2 spectrographs at both, the Las Campanas and Apache Point Observatories. We analyzed the associated spectral features deriving spectral types, as well as the massive star distribution of hundreds of stars along the mentioned lines of sight, finding interesting correlations between the associated heliocentric distances, luminosity classes and spectral types of the newly found massive stellar population. Alvaro Valenzuela Navarro PUC / MAS Verification of star clusters in the direction of the galactic bulge Star clusters traces the star formation history of the Milky Way (MW) and therefore they are essential to describe how the components of the MW formed. There are abundant open clusters on the disk and globular clusters in the halo, but there are not so many verified cluster inside the MW bulge, because of the crowding and high extinction on visual bands. We used VVV photometry and KMOS HKs spectra to characterize kinematics of ~20 candidates located on the galactic bulge. We used also proper motions computed with VVV data and RV computed with cross-correlation method to verify new clusters. (Work in progress) Ana Chies Santos Universidade Federal do Rio Grande do Sul Extragalactic globular clusters and massive galaxy formation