With more than 80 transits observed in the CoRoT lightcurve with a cadence of 32 s, CoRoT-Exo-2b provides an excellent case to search for the secondary eclipse of the planet, with an expected signal of less than 10−4 in relative flux. The activity of the star causes a modulation on the flux that makes the detection of this signal challenging. We describe the technique used to seek for the secondary eclipse, that leads to a tentative 2.5σ detection of a 5.5×10−5 eclipse. If the effect of the spots are not taken into account, the times of transit centers will also be affected. They could lead to an erroneous detection of periodic transit timing variations of ~20 s and with a 7.45 d period. By measuring the transit central times at different depths of the transit (transit bisectors), we show that there are no such periodic variations in the CoRoT-Exo-2b O-C residuals larger than ~10 s.

We present experimental studies on the photoionization and photodissociation processes (photodestruction) of gaseous amino acids and nucleobases in interstellar and interpla-netary radiation analogs conditions. The measurements have been undertaken at the Brazilian Synchrotron Light Laboratory (LNLS), employing vacuum ultraviolet (VUV) and soft X-ray photons. The experimental set up basically consists of a time-of-flight mass spectrometer kept under high vacuum conditions. Mass spectra were obtained using a photoelectron photoion coincidence technique. We have shown that the amino acids are effectively more destroyed (up to 70–80%) by the stellar radiation than the nucleobases, mainly in the VUV. Since polycyclic aromatic hydrocarbons have the same survival capability and seem to be ubiquitous in the ISM, it is not unreasonable to predict that nucleobases could survive in the interstellar medium and/or in comets, even as a stable cation.

After the failure of the 1761 transit to provide a reliable value for the astronomical unit, the focus shifted to the 1769 event, and Britain mounted an ambitious program, with overseas observing parties dispatched to North Cape (Norway), Hudson Bay (Canada) and newly-discovered Tahiti in the Pacific. Lieutenant James Cook was in charge of the Tahitian expedition, ably assisted by fellow-astronomer, Charles Green, and they were supplied by the Royal Society and the Royal Observatory at Greenwich with telescopes and other scientific instruments. The main observing site was set up at Fort Venus, and supplementary transit stations were established on Irioa Island (Moorea) and Taaupiri Island (off the east coast of Tahiti). June 3 was warm and clear, and all observers successfully recorded the transit, but on the journey home ‘the curse of the transit’ prevailed and more than half of them fell ill and died. Back in England, Cook wrote up the transit observations for the Philosophical Transactions of the Royal Society, but for some inexplicable reason only used data obtained at Fort Venus. It was left to Oxford astronomer, Professor Thomas Hornsby, to derive a meaningful figure for the solar parallax, and he utilized the Tahitian data and observations made at four other sites to arrive at a figure of 8$\rlap . ^{\prime\prime}$78. But discordant results obtained by other researchers fuelled controversy over the effectiveness of transits of Venus as a valid means of determining the astronomical unit. In fact, the solar parallax obtained by Hornsby was remarkably similar to the currently-accepted value of 8$\rlap . ^{\prime\prime}$794148, thereby discrediting Beaglehole's oft-quoted claim that the Tahitian observations were a failure. Although more than a dozen men were involved in the Tahitian transit program, most of their records have been lost, and remarkably few of the instruments they employed can now be identified. Yet for those of us with Pacific affiliations, Cook's first voyage to the South Seas occupies a special place in transit of Venus history.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Several uncertain helioseismic findings of potential interest to Jüri about the solar convection zone are briefly discussed, along with some personal optimistic hopes for the future.

The detection of rapidly damped transverse oscillations in coronal loops by Aschwanden et al. (1999) and Nakariakov et al. (1999) gave a strong impetus to the study of MHD waves and their damping. The common interpretation of the observations of these oscillations is based on kink modes. This paper reviews how the observed period and damping time can be reproduced by MHD wave theory when non-uniform equilibrium models are considered that have a transversal variation of the local Alfven velocity. The key point here is that resonant absorption cannot be avoided and occurs as natural damping mechanism for kink waves in non-uniform equilibrium models. The present paper starts with work by Hollweg & Yang (1988) and discusses subsequent developments in theory and their applications to seismology of coronal loops. It addresses the consistent use of observations of periods and damping times as seismological tools within the framework of resonant absorption. It shows that within the framework of resonant absorption infinitely many equilibrium models can reproduce the observed values of periods and damping times.

The recent discovery of pulsating subdwarf B (sdB) stars at the South African Astronomical Observatory (Kilkenny et al. 1997; Koen et al. 1997; Stobie et al. 1997; O'Donoghue et al. 1997) has opened a brand new avenue in the field of asteroseismology. The study of these pulsators (dubbed EC14026 stars, after the prototype) offers the exciting possibility of exploiting the full power of asteroseismology to investigate the sdB phase of stellar evolution, one of the last frontiers in our general understanding of the history of stars.

There is a growing array of supermassive black hole and nuclear star cluster scaling relations with their host spheroid, including a bent (black hole mass)–(host spheroid mass) Mbh–Msph relation and a different (massive compact object mass)–(host spheroid velocity dispersion) Mmco–σ relations for black holes and nuclear star clusters. By combining the observed Mbh ∝ σ5.5 relation with the observed Mnc ∝ σ1.6–2.7 relation, we derive the expression Mbh ∝ Mnc2–3.4, which should hold until the nuclear star clusters are eventually destroyed in the larger core-Sérsic spheroids. This new mass scaling relation helps better quantify the rapid evolutionary growth of massive black holes in dense star clusters, and the relation is consistently recovered when coupling the observed Mnc ∝ Msph0.6–1.0 relation with the recently observed quadratic relation Mbh ∝ Msph2 for Sérsic spheroids.

Non-local thermodynamic equilibrium (NLTE) line formation for neutral and singly-ionized iron is considered through a range of stellar parameters characteristic of cool stars. A comprehensive model atom for Fe I and Fe II is presented. Our NLTE calculations support the earlier conclusions that the statistical equilibrium (SE) of Fe I shows an underpopulation of Fe I terms. However, the inclusion of the predicted high-excitation levels of Fe I in our model atom leads to a substantial decrease in the departures from LTE. As a test and first application of the Fe I/II model atom, iron abundances are determined for the Sun and four selected stars with well determined stellar parameters and high-quality observed spectra. Within the error bars, lines of Fe I and Fe II give consistent abundances for the Sun and two metal-poor stars when inelastic collisions with hydrogen atoms are taken into account in the SE calculations. For the close-to-solar metallicity stars Procyon and β Vir, the difference (Fe II - Fe I) is about 0.1 dex independent of the line formation model, either NLTE or LTE. We evaluate the influence of departures from LTE on Fe abundance and surface gravity determination for cool stars.

White dwarfs with helium-rich atmospheres constitute about one fifth of the white dwarfs hotter than 12,000 K. They appear to have a mass distribution similar to the hydrogen atmosphere (DA) stars, and are similar in other properties. However, the temperature distribution exhibits a deficiency of DB/DO stars in the interval 25,000-45,000 K, which implies evolution in the dominant surface composition as the stars cool. The hottest group of transition DO white dwarfs are the pulsating objects of the PG1159 class. The central star of Kl-16 is a related object, as may be the newly discovered very hot star H1504+65, which shows no detected surface features of either hydrogen or helium.

The question of what information about an asteroid's surface is contained in a measurement of the phase coefficient between phase angles of 10° and 30° is examined in detail. Contrary to some past claims it is shown that absolute reflectivities cannot be derived from phase coefficients. Furthermore, typical asteroid phase coefficients cannot be interpreted unambiguously. This is because the observed phase coefficient may depend as much on the photometric properties of an individual surface element as on the degree of large-scale surface roughness, and these two effects are impossible to separate if only disk integrated measurements are available. The wavelength dependence of asteroid phase coefficients should be small and should contain little information about the surface. In the case of irregular asteroids with macroscopically rough surfaces, the importance of large-scale shadowing, and hence the observed phase coefficient, will depend on the aspect of the asteroid. In such cases, therefore, phase coefficients must be carefully defined to be meaningful It should be possible, in some cases, to estimate the relative surface roughness of two quasi-spherical asteroids by combining photometric and polarimetric observations. For example, if the two asteroids have almost identical polarization curves but quite different phase coefficients, it is likely that the asteroid with the larger phase coefficient has a macroscopically rougher surface.

A number of central stars of planetary nebulae (CSPN) show emission lines in their spectra. Among them about 50 have been classified as [Wolf-Rayet] type (Tylenda et al. 1993). In spite of the fact that these stars probably have masses below 1 M⊙ and luminosities < 104 L⊙ their spectra show emission bands very similar to those of much more massive and luminous Population I Wolf-Rayet stars. We present some preliminary results of an extensive investigation of the [WR]-type CSPN based on the spectroscopic survey described in the Strasbourg-ESO Catalogue of Galactic Planetary Nebulae (Acker et al. 1992).

75 objects have been classified as new planetary nebulae since 1982. They are summarized in Table 1 which gives the designations, names, coordinates and references to the discovery. In the list of misclassified PN (Table 2) 41 objects have been included; Table 3 presents objects with incorrect identification in CGPN. The main properties of a PN and of its nucleus are given in a summary which can be useful for a correct classification of planetaries.

The shift of the emitted frequencies towards lower frequencies during a solar outburst is usually interpreted as due to a progressive rarefaction of the emitting gas. If one assumes that the emitted frequency is identical with the plasma frequency and furthermore that the density of the emitting plasma is similar to the density of the solar corona at the location of the radiating material, then it follows that this material is subject to an acceleration throughout the solar corona which compensates or exceeds the effect of the gravitational field of the sun.

During the 1980s, numerical simulations showed that dynamic growth of a barlike mode in initially axisymmetric, equilibrium protostars does not lead to prompt binary formation, i.e., fission. Instead, such evolutions usually produce a dynamically stable, spinning barlike configuration. In recent years, this result has been confirmed by numerous groups using a variety of different hydrodynamical tools, and stability analyses have convincingly shown that fission does not occur in such systems because gravitational torques cause nonlinear saturation of the mode amplitude. Other possible routes to fission have been much less well scrutinized because they rely upon a detailed understanding of the structure and stability of initially nonaxisymmetric structures and/or evolutions that are driven by secular, rather than dynamic processes. Efforts are underway to examine these other fission scenarios.

OH and H2O masers in star forming regions are important because they are readily detectable indicators of star formation and because they provide unique information on the kinematics and physical conditions in high density regions (106 – 1010 cm−3) surrounding young stars, regions which cannot be studied by other means at present. The Jodrell Bank MERLIN interferometer has been used to map a sample of OH and H2O masers associated with bipolar molecular outflows. The maps of Cepheus A show that the masers are closely associated with the densest compact H II regions at the centre of the flow. The masers appear to be located at the inner edges of the circumstellar disk thought to play a role in collimating the outflow. It is suggested that the H2O masers trace the interaction between the stellar wind and the dense molecular gas, and the OH masers trace shocks propagating into the molecular gas. Rapid and sometimes correlated variations in the maser emission suggest that radiative pumping is likely in this source (Rowland and Cohen, Mon. Not. R. Astr. Soc. in press). Study of the other sources is still in progress.

Two main mechanisms have been proposed to explain the origin of the slowly varying component [1] of the decimeter-wavelength radiation from the sun. Both theories [2, 3, 4] are based on the facts that (a) this component of the sun's radiation is relatively steady in output for periods of days; (b) it originates from active regions on the sun; and (c) its magnitude is closely related to the sunspot area in the region.

We developed a new quick pseudo-3D photoionization code based on Cloudy (Ferland et al.) and IDL (RSI) tools. The code is running the 1D photoionization code Cloudy various times, changing at each run the input parameters (e.g. inner radius, density law) according to an angular law describing the morphology of the object. Then a cube is generated by interpolating the outputs of Cloudy. In each cell of the cube, the physical conditions (electron temperature and density, ionic fractions) and the emissivities of lines are determined. Associated tools (VISNEB and VELNEB_3D) are used to rotate the nebula and to compute surface brightness maps and emission line profiles, given a velocity law and taking into account the effect of the thermal broadening and eventually the turbulence. Integrated emission line profiles are computed, given aperture shapes and positions (seeing and instrumental width effects are included). The main advantage of this tool is the short time needed to compute a model (a few tens of minutes).

The state of our knowledge concerning the chemical composition of H II regions in the Magellanic Clouds is reviewed. New abundances derived from all modern published spectroscopy are presented. Some of the implications of the results regarding the nucleosynthesis of the elements and galactic chemical evolution are noted.

The Starlight Initiative brings a new view of the night sky and of its value enhancement, claiming the access to starlight as a scientific, environmental, and cultural right of humankind. Night sky quality has been seriously damaged in the last years because of light and atmospheric pollution, and an international action in favour of intelligent outdoor lighting is urgently needed. After the promulgation of the Starlight Declaration, we are jointly working with UNESCO, the World Heritage Centre, the MaB Programme, and other international institutions in the development of Starlight Reserves as exemplary areas that would act as models for the recovery of the heritage associated to star observation. The possibility arises to design and launch new tourist products and destinations based on astronomy and starry sceneries.

We are conducting a wide-angle Hα survey of the southern sky at CTIO using a robotic CCD camera. The survey consists of 283 fields covering the sky from δ = −90° to δ = +10°, with the same centers as those in the IRAS Sky Survey Atlas. As of July 1, 1998, it was about 45% complete. When all the images are obtained and fully processed, the survey will be made available to the scientific community on the web and on CD-ROM.