As part of a long term observational project, we are investigating the macroturbulent broadening in O and B supergiants (Sgs) and its possible connection with spectroscopic variability phenomena and stellar oscillations. We present the first results of our project, namely firm observational evidence for a strong correlation between the extra broadening and photospheric line-profile variations in a sample of 13 Sgs with spectral types ranging from O9.5 to B8.

The National Observatory of Brazil was established in 1827 to study the problems of latitude and time. Time and latitude programs are still an important part of its work, but are now accompanied by increasing activity in the fields of geophysics, astrophysics and radio astronomy.

It has been estimated that up to several tens of globular clusters in our Galaxy remain undiscovered, because they are hidden by the dust. Most of those clusters are expected to be in the bulge area, but some may be anywhere in the galactic plane. This search is based on the use of IRAS catalogs as candidate lists for the obscured globular clusters. It was found that the properties of detected known clusters are sufficiently distinct for a meaningful sifting through the PSC. A sequence of statistical “filters”, described below, was applied on the PSC, until a couple of hundred most promising candidates were found in the bulge.

In the era of large spectroscopic surveys, it is vital that selection effects are taken into account when making conclusions about the stellar populations of the Galaxy. Here we use the Galactic disc sample of stars from the Gaia-ESO Survey internal data release 4 (GES iDR4), applying the published selection function to characterise the vertical extent of the chemically defined thick and thin discs.

In this talk I give a short overview of models for spectral lines in Be stars disks which I think are quite instructive. I then examine the arguments for my own model assumptions and discuss selected topics concerning radiative line transfer calculations in three dimensions. We show that symmetric Hα emission lines of Be stars can be understood in terms of Keplerian disks. It is also demonstrated that one-armed global disk oscillations provide the best available solution to understand the long-term V/R variations in Be star emission lines.

A brief review is given of the major results from the last twenty years of astronomical site-testing in Antarctica. Suggestions are made for how to resolve some outstanding questions, such as the infrared sky background at Antarctic sites other than South Pole station.

We present high quality polarimetric observations with the Effelsberg radio telescope of the Crab pulsar at 8.35 GHz using a new sensitive receiver with a very large bandwidth. We present our observations and discuss them in the context of the conclusions reached by Moffett & Hankins (1999) about the geometry and the origin of the various pulse components.

The kinematic and dynamical properties of galaxy stellar halos are difficult to measure because of the faint surface brightness that characterizes these regions. Spiral galaxies can be probed using the radio Hi emission; on the contrary, early-type galaxies contain less gas, therefore alternative kinematic tracers need to be used. Planetary nebulae (PNe) can be easily detected far out in the halo thanks to their bright emission lines. It is therefore possible to map the halo kinematics also in early-type galaxies, typically out to 5 effective radii or beyond. Thanks to the recent spectroscopic surveys targeting extra-galactic PNe, we can now rely on a few tens of galaxies where the kinematics of the stellar halos are measured. Here, I will review the main results obtained in this field in the last decades.

Spectra of Uranus were obtained with the 122 cm reflector of the Crimean Astrophysical Observatory using the spectrometer of the Main Astronomical Observatory of the Ukrainian Academy of Sciences (Kiev), in March 1969. A photomultiplier (Soviet type 79) was used in a pulse counting mode, and the dispersion of the spectrometer at the camera focal plane was 15 Å/mm.

We present spatially resolved X-ray spectra taken with the EPIC cameras of XMM-Newton of a sample of 17 cooling clusters and three non-cooling clusters for comparison. The deprojected spectra are analyzed with a single-temperature model. All cooling clusters show a central decrement of the average temperature, most of them of a factor of $\sim$2. Three clusters show a weak temperature decrement, while two others have a very strong temperature decrement. We investigate the role of heat conduction by electrons and find that the theoretically predicted conductivity rates are not high enough to balance radiation losses.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Observations of the night-sky brightness were organized at 106 places in Japan by a promotion of the Environmental Agency with the help of many local governments. Two kinds of measurements were carried out: 1) Number of stars were counted in a region of triangle formed by Alpha Lyr, Epsilon Lyr, and Zeta Lyr by at least 10 contributors at each point. 2) Photographs of a star field at the zenith at each point were taken with the same type of camera and film. These results gave us a good idea on distribution of night-sky brightness in Japan.

This conference is concerned with the very high resolution imaging of cosmic sources in many parts of the electromagnetic spectrum. Various techniques are now available and the equipment is often automated and highly sophisticated but the term ‘very high angular resolution’ is comparative. Many of the problems existed over forty years ago when the best resolving power was about half a degree and the two major radio ‘stars’ appeared to be point sources. Very high resolution imaging in those days was the struggle to reach one minute of arc and Hanbury Brown had set his sights on considerably better than one second of arc with the concept of the intensity interferometer. The dream was to achieve a resolving power comparable to that of optical telescopes.

The present short notes on cosmology start with two conclusions based on observational data. The first of them is the well-known conclusion that the Universe from the global point of view is at the present epoch of its evolution in a uniform and isotropic expansion. If we accept the very convincing arguments of Bondi (1962) that the geometry of the cosmic space is Riemannian, its properties are described at the present epoch of the cosmic evolution by the well-known Robertson-Walker metric expressing the cosmological principle (Robertson, 1935, 1936; Walker, 1936). The form of the geodesical lines depends on the assumed theory of gravitation. For instance, in the closed Friedman world model they are cycloids with a singularity at the start of the expansion.

Studies of brown dwarfs as a distinct galactic population have been largely pioneered by dedicated, vast-area surveys at deep optical and near-infrared wavebands. The Two Micron All Sky Survey has, because of its full-sky coverage and depth, been the most successful at providing new targets for further study. The author briefly reviews some of the ways in which 2MASS data have been used by brown dwarf researchers. One of the by-products – namely the 2MASS Team's follow-up spectroscopy of brown dwarf candidates – is potentially valuable as a scientific resource itself and is also being released to the public.

A number of recent studies have claimed that the double red clump observed in the Milky Way bulge is a consequence of an X-shaped structure. In particular, Ness & Lang (2016) report a direct detection of a faint X-shaped structure in the bulge from the residual map of the Wide-Field Infrared Survey Explorer (WISE) image. Here we show, however, that their result is seriously affected by a bulge model subtracted from the original image. When a boxy bulge model is subtracted, instead of a simple exponential bulge model as has been done by Ness & Lang, we find that most of the X-shaped structure in the residuals disappears. Furthermore, even if real, the stellar density in the claimed X-shaped structure is way too low to be observed as a strong double red clump (dRC) at l = 0°.

V647 Tau was observed during a 1997 STEPHI campaign; 228 hr of observations in v were obtained, together with another 50 hr of simultaneous data in y. The data were analyzed and main results are discussed in the text.

In 1964 a conference was held at Flagstaff, Arizona, in honour of Ejnar Hertzsprung. At this conference Martin Schwarzschild presented the inaugural address. The title was ‘New Impetus to Astrometry’. I was so much impressed by everything what he, as an astrophysicist, had to say that I have always remembered his analysis of important astrometric problems with admiration. Nine years after the Flagstaff Conference, I find it appropriate to open this Symposium in referring to Schwarzschild's lecture and in presenting my views on recent developments and on progress which I expect in the future.

We present a matched-filter, surface density map of the “300 km/s” stream recently discovered in the vicinity of the ultrafaint dwarf galaxy Segue 1.