We present an analysis of photometric and spectroscopic observations of the symbiotic binary system RX Pup with the aim of developing a reliable binary model for the system and identifying mechanisms ...responsible for its spectacular activity. The binary is composed of a long-period Mira variable surrounded by a thick dust shell and a hot ̃ 0.8 Msun white dwarf companion. The hot component produces practically all activity observed in the UV, optical and radio range, while variable obscuration of the Mira by circumstellar dust is responsible for long-term changes in the near-infrared magnitudes. The observations show that RX Pup underwent a nova-like eruption during the last three decades. The hot component contracted in radius at roughly constant luminosity from 1975 to 1986, and was the source of a strong stellar wind, which prevented it from accreting material lost in the Mira wind. Around 1988/9 the hot component turned over in the Hertzsprung-Russell (HR) diagram and by 1991 its luminosity had faded by a factor of ̃ 30 with respect to the maximum plateau value and the hot wind had practically ceased. By 1995 the nova remnant started to accrete material from the Mira wind, as indicated by a general increase in intensity of the optical continuum and H i emission. The quiescent spectrum resembles the quiescent spectra of symbiotic recurrent novae, and its intensity indicates that the hot component must accrete as much as ̃ 1 per cent of the Mira wind, which is more or less the amount predicted by Bondi-Hoyle theory. The earliest observational records from the 1890s suggest that another nova-like eruption of RX Pup occurred around 1894.
We present detailed chemical abundances, radial velocities and orbital parameters for FSR 1758, a recently discovered star cluster in the direction of the Galactic Bulge. High resolution (R~42,000) ...spectra were obtained using the Magellan/Clay telescope instrumented with MIKE echelle spectrogragh, wavelength range 4900-8700 \AA. Cluster membership was determined using Gaia DR2 proper motions and confirmed with our radial velocity measurements. We find metallicity consistent with previous photometric estimates for this cluster, Fe/H = -1.58+-0.03 dex, with a small, 0.08 dex, spread. While other studies have suggested this massive object may be the result of a previous accretion event, our results are consistent with Milky Way Halo globular clusters with characteristic Na-O anti-correlations found for the metal-poor cluster members. The mean radial velocity of the cluster, +226.8+-1.6 km/s with a small velocity dispersion, 4.9+-1.2 km/s, is typical for globular clusters. We also confirm a retrograde Galactic orbit that appears to be highly eccentric.
We present a spectroscopic study of the N159/N160 massive-star forming region south of 30 Doradus in the Large Magellanic Cloud, classifying a total of 189 stars in the field of the complex. Most of ...them belong to O and early B spectral classes; we have also found some uncommon and very interesting spectra, including members of the Onfp class, a Be P Cygni star, and some possible multiple systems. Using spectral types as broad indicators of evolutionary stages, we considered the evolutionary status of the region as a whole. We infer that massive stars at different evolutionary stages are present throughout the region, favoring the idea of a common time for the origin of recent star formation in the N159/N160 complex as a whole, while sequential star formation at different rates is probably present in several subregions.
New spectroscopic data of the peculiar interacting binary system W Serpentis in the region of H-alpha and H-beta are being reported, through the phase interval 0.95-0.16 p. We recognize the six sets ...of lines described by Sahade and Struve (1957). In addition to the Fe II concentration lines in the blue region, reported in earlier work, we find the presence of O I concentration in the red that confirms the existence of a low density region surrounding the system, as suggested by Sahade and Struve (1957). We confirm the difficult interpretation of features in the Mg II 4481 A region. We present radial velocities from He I for the first time.
ESO Messenger 155, (2014), 29-32 The VISTA Variables in the V\'ia L\'actea (VVV) survey is one of six public
ESO surveys, and is now in its 4th year of observing. Although far from being
complete, ...the VVV survey has already delivered many results, some directly
connected to the intended science goals (detection of variables stars,
microlensing events, new star clusters), others concerning more exotic objects,
e.g. novae. Now, at the end of the fourth observing period, and comprising
roughly 50% of the proposed observations, the actual status of the survey, as
well some of the results based on the VVV data, are presented.
In this poster we show our preliminary analysis of DIBs (Diffuse Interstellar Bands) and other interstellar absorption lines with the purpose of understanding their origin and their relationship with ...extinction. We use the biggest Galactic O-star blue-violet spectroscopic sample ever (GOSSS, see contribution by Maíz Apellániz at this meeting). This sample allows a new insight on this topic because of the adequacy of O-star spectra, the sample number (700 and increasing, 400 used here), and their distribution in the MW disk. We confirm the high correlation coefficients between different DIBs and E(B - V), though the detailed behavior of each case shows small differences. We also detect a moderately low correlation coefficient between Ca II {\lambda}3934 (Ca K) and E(B - V) with a peculiar spatial distribution that we ascribe to the relationship between line saturation and velocity profiles for Ca II {\lambda}3934.
The Galactic O-Star Spectroscopic Survey (GOSSS) is a project that is observing all known Galactic O stars with B < 13 (~2000 objects) in the blue-violet part of the spectrum with R~2500. It also ...includes two companion surveys (a spectroscopic one at R~1500 and a high resolution imaging one). It is based on v2.0 of the Galactic O star catalog (v1, Maíz Apellániz et al. 2004; v2, Sota et al. 2008). We have completed the first part of the main project. Here we present results on the first 400 objects of the sample.
PDF
