Hot stars in young massive clusters: Mapping the current Galactic metallicity

de la Fuente, Diego; Najarro, Francisco; Davies, Ben; Trombley, Christine; Figer, Donald F.; Herrero, A.
Bibliographical reference

Massive Stars: From α to Ω, held 10-14 June 2013 in Rhodes, Greece; Online at http://a2omega-conference.net, id.145

Advertised on:
6
2013
Number of authors
6
IAC number of authors
1
Citations
0
Refereed citations
0
Description
Young Massive Clusters (YMCs) with ages < 6 Myr are ideal tools for mapping the current chemical abundances in the Galactic disk for several reasons. First of all, the locations of these clusters can be known through spectrophotometric distances. Secondly, their young ages guarantee that these objects present the same chemical composition than the surrounding environment where they are recently born. Finally, the YMCs host very massive stars whose extreme luminosities allow to accomplish detailed spectroscopic analyses even in the most distant regions of the Milky Way. Our group has carried out ISAAC/VLT spectroscopic observations of hot massive stars belonging to several YMCs in different locations around the Galactic disk. As a result, high signal-to-noise, near-infrared spectra of dozens of blue massive stars (including many OB supergiants, Wolf-Rayet stars and a B hypergiant) have been obtained. These data are fully reduced, and NLTE spherical atmosphere modeling is in process. Several line diagnostics will be combined in order to calculate metal abundances accurately for each cluster. The diverse locations of the clusters will allow us to draw a two-dimensional chemical map of the Galactic disk for the first time. The study of the radial and azimuthal variations of elemental abundances will be crucial for understanding the chemical evolution of the Milky Way. Particularly, the ratio between Fe-peak and alpha elements will constitute a powerful tool to investigate the past stellar populations that originated the current Galactic chemistry.