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Estarnos llevando a cabo un monitoreo fotomètrico de una muestra de sistemas binarios eclipsantes con período variable, considerados preliminarmente como semiseparados o en contacto, a fin de determinar sus parámetros astrofísicos fundamentales y caracterizar la interacción entre sus componentes. En este trabajo presentamos las curvas de luz de cuatro sistemas y el modelado de dos de ellas. Verificamos que la fotometría obtenida es adecuada para los objetivos del proyecto. Conjuntamente presentamos la primera clasificación espectral de siete de estos sistemas., We are conducting a photometric monitoring of a sample of eclipsing binary systems with variable periods, preliminarly considered as semidetached or in contact. We aim at determining the fundamental astrophysical parameters of these objects and at characterizing the interactions between their components. In this work we present the light curves of four systems and the modeling of two of them. The photometry has revealed to be adequate for the project purposes. We also report the first spectral classification of seven systems from the sample., Facultad de Ciencias Exactas, Instituto de Astrofísica de La Plata

Se estudiaron los cúmulos inmersos DBS 77, 78, 102, 160 y 161 localizados en el plano Galáctico en el cuarto cuadrante de la Vía Láctea y el medio interestelar (MIE) circundante. Se analizó fotometría UBVIc (SOAR) y espectroscopía infrarroja (NTT, ESO). Estos datos fueron complementados con las bandas JHK (VVV+2MASS), H I en 21 cm (SGPS), 1.4 GHz (ATCA) y 4.85 GHz (PMN). Se realizó un análisis multibanda y clasificación espectral de las estrellas brillantes de cada zona. Se identificaron también, estructuras del MIE posiblemente vinculadas con los cúmulos. Finalmente, se obtuvieron valores preliminares para los parámetros fundamentales de los cúmulos estudiados y de las estructuras del MIE. Se estudió la vinculación entre ambos, We study the embedded clusters DBS77, 78, 102, 160, and 161 located in the Galactic plane in the fourth quadrant of the Milky Way and the surrounding interstellar medium (ISM). We analyzed UBVIc photometry (SOAR) and infrared spectroscopy (NTT, ESO). We complemented these data with JHK (VVV2MASS), HI 21 cm bands (SGPS), 1.4 GHz (ATCA), and 4.85 GHz (PMN). We did multiband analysis and spectral classification of the brightest stars in each area. We also identified the ISM structures possibly related to the clusters. Finally, we obtained the main parameters of the studied clusters, the structures of the ISM and the link between them., Instituto de Astrofísica de La Plata

We present a study of the eclipsing symbiotic binary FN Sgr with a period of 568.3 days determined photometrically and confirmed spectroscopically. The hot component underwent a 2.5 mag eruption covered by most of our spectroscopic observations. In particular, we have determined for the first time spectroscopic orbits based on the radial velocity curves for both components. A set of blue absorption lines resembling an A-F type star is present in all our spectra and they seem to be associated with the hot component. Based on the light curve, we derive the red giant’s radius (140 R ☉) and the orbital inclination (i = 80◦). We find that FN Sgr is similar to other S-type symbiotic binaries, composed by an M 5-type giant (M g = 1.5 M ☉ ) and a hot white dwarf (M h = 0.7 M ☉ , R h = 0.2 R ☉ ) with a binary separation of ∼1.6 AU. The red giant is just filling its Roche lobe and a geometrically and optically thick accretion disk is likely to be present around the low-mass accretor. The evolution of Th and Lh along the active phase argues in favour of accretion disk instabilities similar to those of Z And. We have also studied spectral changes and photometric variations as a function of both the hot component activity and the orbital motion., Facultad de Ciencias Astronómicas y Geofísicas