The star R Corona Borealis (R CrB) shows forbidden lines of [O II], [N II], and [S II] during the deep minimum when the star is fainter by about 8 to 9 magnitudes from normal brightness, suggesting the presence of nebular material around it. We present low and high spectral resolution observations of these lines during the ongoing deep minimum of R CrB, which started in July 2007. These emission lines show double peaks with a separation of about 170 km/s. The line ratios of [S II] and [O II] suggest an electron density of about 100 cm−3. We discuss the physical conditions and possible origins of this low density gas. These forbidden lines have also been seen in other R Coronae Borealis stars during their deep light minima and this is a general characteristic of these stars, which might have some relevance to their origins.

The Sun has been suggested to have a slightly low refractory-to-volatile abundance ratio when compared with field solar twins. This result may be interpreted as due to the fact that the refractory elements were trapped in rocky planets at the formation of the Solar System.

A detailed and differential chemical abundance study was already performed in order to investigate this hypothesis in solar analogs with and without detected planets using high-resolution and high-S/N HARPS and UVES spectra of a relatively large sample of solar analogs with and without planets. We obtained very similar behaviours for both samples of stars with and without planets, even for two stars with super-Earth-like planets, which may indicate that this solar trend may not be related to the presence of terrestrial planets.

The depletion signature should be imprinted once the convection zone reaches the current size. This suggests that stars hotter than the Sun should show this effect enhanced, due to their narrower convective zone. However, to avoid non-LTE, 3D, and other effects, we need to identify “hot” analogs with a Teff ~ 6100 K, to perform a differential analysis.

Here, we present the preliminary results of our analysis using HARPS and UVES high-resolution and high-S/N spectra of a sample of ~ 60 “hot”analogs with and without planets, trying to search for some “hot” reference analogs.

The complexities of ultracool atmospheres are best confronted by observations of ultracool dwarfs (UCDs) with well known physical properties (luminosity, mass, Teff, log(g), [M/H]), so-called “benchmark objects.” We present two discoveries from a new WISE+2MASS search for benchmark wide companions to Hipparcos and Gliese stars. This survey combination provides a powerful tool to confirm new companions using color-magnitude and common proper motion selections, and also yield full NIR-MIR measurements of the ultracool emission. These primary companions are providing important constraints on the age and composition of the benchmark brown dwarf, and the new discoveries add to our growing population of benchmarks that is providing crucial tests of ultracool physics.

High resolution spectroscopic data of a large sample of galactic planetary nebulae with [WC] central stars ([WC]PNe) are analyzed to determine their kinematical behavior. Their heliocentric velocities have been determined with a precision better than a few km/s. Distances obtained from the literature are used to derive the peculiar velocities of the objects. Our preliminary results are: (a) The [WC] PNe are distributed in the galactic disk and they appear more concentrated than the normal PNe. (b) Separating the sample in Peimbert's types, we find that Type I PNe show in general low peculiar velocities (<50 km/s) except for a couple of objects apparently belonging to the galactic bulge. For the other [WC]PNe, most of them belong to the Peimbert's Type II (defined as having Vpec ≤ 60 km/s). However there is an important fraction (28%) showing Vpec larger than 60 km/s therefore they are classified as Peimbert's Type III.

We are extending our search for faint PNe in the LMC to include the outer 56 deg2 area not covered in the original UKST survey of the central 25eg2 region. Candidate PNe have been selected using the Magellanic Cloud Emission Line Survey (MCELS) and the first round of observations has yielded 93 new LMC PNe while confirming the 102 previously known PNe in the outer LMC. We plan to continue our spectroscopic object identification program until we cover all our remaining candidates in the survey area. These observations, providing medium and high resolution spectra from λ3650Å to λ6900Å will additionally be used to measure fluxes for a series of research projects including luminosity functions, abundances and LMC kinematics.

In this work, we present the first catalogue of optically variable sources observed by the Optical Monitoring Camera (OMC), with information about the variability of more than 5000 objects and periodicity of ~ 1000 sources.

The internal heat loss or cooling of a planet determines its structure and evolution. We address in a consistent fashion the coupling between the day and the night sides by means of model atmosphere calculations with heat redistribution. We assume that a strong convection leads to the same entropy on the day and night side and that the gravity is the same on both hemispheres. We argue that the core cooling rate from the two hemispheres of a strongly irradiated planet may not be the same and that the difference depends on several important parameters. If the day-night heat redistribution is very effective, or if it takes place at a large optical depth, then the day-side and the night-side cooling may be comparable. However, if the day-night heat transport is not effective, or if it takes place at a shallow optical depth, then there can be a big difference between the day-side and the night-side cooling and the night side may cool more effectively. If the stellar irradiation gets stronger e.g. due to the stellar evolution or migration, this will reduce both the day and the night side cooling. Enhanced metallicity in the atmosphere acts as a “blanket” and reduces both the day- and the night-side cooling. However, the stratosphere on the day side of the planet can enhance the day-side cooling since its opacity acts as a “shield” which screens the stellar irradiation. These results might affect the well known gravity darkening and bolometric albedo effects in interacting binaries, especially for strongly irradiated cold objects.

The four known O(He) stars are the only amongst the hottest post-AGB stars whose atmospheres are composed of almost pure helium. Thus, their evolution deviates from the hydrogen-deficient post-AGB evolutionary sequence of carbon-dominated stars like e.g. PG 1159 stars. The origin of the O(He) stars is still not explained. They might be either post-early AGB stars or the progeny of R Coronae Borealis stars. We present preliminary results of a non-LTE spectral analysis based on FUSE and HST/COS observations.

We present a photometric study of the newly discovered low-mass eclipsing binary NSVS 01031772 Cam based on observations obtained at Ondřejov observatory from 2007 – 2011.

“Water fountains” (WF) are post-AGB stars characterized by very fast and often bipolar jets in the water maser line at 22 GHz. We conducted a survey of the CO and 13CO line emission using the IRAM 30m radio telescope of all the sources visible from the observatory. Over a total of 10 WFs observed, we identified CO and 13CO associated to IRAS 18460-0151 and IRAS 18596+0315. As the CO line emission is ubiquitous in the Galactic plane, the confirmed detections have met strict criteria to consider these cases as confirmed detections. The velocity components associated to the WFs are ~ 40 km s−1 wide, centered at the star velocity, present only at the star position, and detected in the four observed transitions, the CO and 13CO J=1→0 and 2→1 lines. A preliminary study, based on line ratios, indicates that this molecular component has a high opacity, and a very low 12C/13C isotopic ratio.

Central stars of planetary nebulae (CSPN) have a relatively large mass interval, so that it is expected that these stars also have different ages, typically above 1 Gyr. Apart from the properties of the CSPN themselves, the problem of age determination is also important in the context of the chemical evolution of the Galaxy, for instance in the understanding of the time variation of chemical abundance gradients. In this work, we estimated the ages of a sample of CSPN on the basis of some correlations between their kinematic properties and the expected ages. According to these correlations, the observed dispersions in the U, V, W velocities are uniquely defined by the stellar ages. The adopted correlations were derived from the recent Geneva-Copenhagen survey of galactic stars. Preliminary results suggest the most CSPN in the galactic disk have ages under 3 Gyr. These results are also compared with some recent age distributions based on independent correlations involving the nebular chemical abundances.

The puzzling W-UMa type binary TZ Boo has been monitored at the University of Patras, Observatory from March to July 2010. Photometric solutions were determined through an analysis of the complete BVRI light curves with PHOEBE (Wilson-Devinney code) and published spectroscopic data. This low mass ratio binary turns out to be a deep overcontact system with f = 52.5% of A-subtype. A conservative spot model has been applied to fit the particular features of light curves. Based on our 7 new light minimum times and all others compiled from the literature over 70 years, we studied the orbital period from the O-C curve.

We derive the chlorine abundances in a sample of nearby planetary nebulae (PNe) and H II regions that have some of the best available spectra. We use a nearly homogeneous procedure to derive the abundance in each object and find that the Cl/H abundance ratio shows similar values in H II regions and PNe. This supports our previous interpretation that the underabundance we found for oxygen in the H II regions is due to the depletion of their oxygen atoms into organic refractory dust components. For other elements, the bias introduced by ionization correction factors in their derived abundances can be very important, as we illustrate here for sulfur using photoionization models. Even for low-ionization PNe, the derived sulfur abundances can be lower than the real ones by up to 0.3 dex, and the differences found with the abundances derived for H II regions that have similar S/H can reach 0.4 dex.

We give new values of the structural coefficients ηj, and related quantities, for realistic models of distorted stars in close binary systems. Our procedure involves numerical integration of Radau's equation for detailed structural data for stellar models taken from the EZWeb compilation of the Department of Astronomy, University of Wisconsin-Madison.

NGC 5189 is a particularly interesting planetary nebula (PN) displaying multiple bipolar structures. This type of morphology is generally attributed to multiple mass loss events believed to originate from a precessing central source. In order to better understand this, once dubbed chaotic PN, we have investigated optical imaging combined with low- and high- resolution spectroscopic data to dissect its components. The imaging reveals three and possibly four well defined bipolar lobes showing a misalignment with respect to the central torus, although sharing the same geometric center. The high nitrogen levels detected in the elongated filaments/condensations surrounding the nebula and at the torus location highlight the presence of low ionization structures as well as the possible occurrence of shocks in the areas perturbed by large dynamical motions. Finally the kinematical study indicates moderate expansion velocities (35 km.s−1 in the western lobe, 33 km.s−1 in the central region and 44 km.s−1 in the eastern lobe). We also notice the asymmetry of the [NII] distribution and the velocities inside NGC 5189 between its North-West and South-East components.

In this study, we present the preliminary light curve analysis of the contact binary SW Lac, using B, V light curves of the system spanning 2 years (2009 - 2010). During the spot modeling process, we used the information coming from the Doppler maps of the system, which was performed using the high resolution and phase dependent spectra obtained at the 2.1m Otto Struve Telescope of the McDonald Observatory, in 2009. The results showed that the spot modeling from the light curve analysis are in accordance with the Doppler maps, while the non-circular spot modeling technique is needed in order to obtain much better and reliable spot models.

The low surface brightness usually associated with nebulae mixing with the ISM has long been a substantial obstacle in the observation and statistical study of these interactions. Thanks to the detection capability of the INT Photometric H-alpha Survey (IPHAS), in terms of sensitivity and imaging resolution, we were able to detect and select tens of examples of candidate Planetary Nebulae apparently at different stages of interaction with the interstellar medium (PNe-ISM hereafter) following the Wareing et al. (2007) classification. A spectroscopic investigation was conducted with the San Pedro Martir 2.1m telescope (SPM) in Mexico and we present the first results involving a proper classification and analysis of our candidates. The main difficulty is visually separating PNe-ISM from other faint asymmetric nebulosities such as old HII regions, SNRs and general diffuse H-alpha structures. This investigation is a first step in a more comprehensive study of PNe-ISM as more candidates are uncovered by the IPHAS team.

Our photometric CCD observations of the short-period cataclysmic star AR UMa in 2008 during its low state revealed light variability with a bigger period (by around 10%) and considerably smaller amplitudes than the previous ones. The light curve had a single-wave shape, opposite to the previously observed low states which revealed doubled-humped shape.

I. Hubeny Does anyone from the panel have a theme question to start with today?

V. Trimble It's another one-liner: From an active galaxy meeting many years ago when people talked about spiral structure. I was reminded by Dr. Rucinski's talk of Lodewijk Woltjer's remark: “The larger our ignorance, the stronger the magnetic field.”

X-ray observations of young Planetary Nebulæ (PNe) have revealed diffuse emission in extended regions around both H-rich and H-deficient central stars. In order to also reproduce physical properties of H-deficient objects, we have, at first, extended our time-dependent radiation-hydrodynamic models with heat conduction for such conditions. Here we present some of the important physical concepts, which determine how and when a hot wind-blown bubble forms. In this study we have had to consider the, largely unknown, evolution of the CSPN, the slow (AGB) wind, the fast hot-CSPN wind, and the chemical composition. The main conclusion of our work is that heat conduction is needed to explain X-ray properties of wind-blown bubbles also in H-deficient objects.