We model the K-correction for emission lines formed on the irradiated face of companion stars in compact binaries. We compute this K-correction in a general approach as function of the mass ratio and the disc flaring angle. Our results, combined with the detection of high excitation emission lines arising from the donor star, can be used to set constraints to the masses of neutron stars and black holes in persistent Low Mass X-ray Binaries (LMXBs).

The application of our model to X1822-371 (Muñoz-Darias, Casares & Martínez-Pais 2005) lends strong support to the presence of a massive neutron star in this LMXB (i.e. MNS > 1.6M⊙). Here, we also present the K-correction for the Black Hole binary GX339-4, where we obtain a solid lower limit to the black hole mass of MBH > 5.8M⊙.

We studied the origin of quasi-periodic oscillations (QPOs) of X-rays in black hole candidates by three-dimensional global resistive magnetohydrodynamic simulations of accretion disks. Initial state is a rotating disk threaded by weak toroidal magnetic fields. General relativistic effects are simulated by using the pseudo-Newtonian potential. When the temperature of the outer disk decreases, the accreting matter accumulates into an inner torus.

We found that the inner torus is deformed into a crescent shape and that it shows sawtooth-like oscillations of magnetic energy with frequency 3-5Hz when the mass of the black hole is 10M⊙. The magnetic energy inside the torus is amplified until magnetic reconnection suddenly releases the accumulated magnetic energy. A new cycle of the oscillation starts when magnetic energy is amplified again. We found that high frequency QPOs with frequency around 100Hz in stellar mass black holes are excited when sawtooth-like oscillation appears in the inner torus.

We present and discuss the results of a comprehensive analysis of magnetic field measurements for a group of seven young Herbig Ae/Be stars obtained using low-resolution spectropolarimetry with FORS1 at the VLT. The first definite evidence for the presence of surface magnetic fields has been found only recently in the Herbig Ae stars HD 139614, HD 31648 and HD 144432 (Hubrig et al. 2004; Hubrig et al. 2006) from the measurement of circular polarization in Ca II lines and hydrogen lines located in the spectral region from 3900 to 4900 Å. The unusual Herbig Ae star HD 190073 shows distinctive Zeeman features in the Ca II doublet which displays several components in both H and K lines. The most recent analysis carried out separately for different lines has shown that Zeeman features appear in metallic lines in all seven objects of our programme. The most prominent of them are seen in lines of the CaII doublet possibly of both photospheric and circumstellar origin. The circumstellar Balmer line components demonstrate the existence of a magnetic field in HD 144432 and HD 31648. The photospheric components of these lines with signs of magnetic field are present in HD 144668.

We review our recent work on the formation and evolution of disks within triaxial dark matter (DM) halos by means of numerical simulations, including star formation and feedback from stellar evolution. The growing disks are strongly influenced by shapes of DM halos and modify them in turn. Disk parameters are in a broad agreement with those in the local universe. Gas-rich stellar bars grow in tandem with the disk and facilitate the angular momentum redistribution in the system and radial gas inflow. Nested bars appear to form as a by-product. Interactions between various non-axisymmetric components—bars, disks and halos lead to decay of bars or washing out of ellipticity in the inner halo.

Here we discuss the possibility to use gravitational microlensing in order to probe the geometry around a massive black hole. Taking into account that lensed quasars are emitting X-rays which come from the heart of these objects, we investigated the influence of microlensing on the Fe Kα line shape originated in Schwarzschild and Kerr metrics.

In theoretical as well as practical issues of the asteroidal hazard problem, it is important to be able to assess the degree of predictability of the orbital motion of asteroids. Some asteroids move in a virtually predictable way, others do not. The characteristic time of predictability of any motion is nothing but the Lyapunov time (the reciprocal of the maximum Lyapunov exponent) of the motion. In this report, a method of analytical estimation of the maximum Lyapunov exponents of the orbital motion of asteroids is described in application for two settings of the problem. Namely, the following two types of the motion are considered: (1) the motion close to the ordinary or three-body mean motion resonances with planets, and (2) the motion in highly eccentric orbits subject to moderately close encounters with planets. Whatever different these settings may look, the analytical treatment is universal: it is performed within a single framework of the general separatrix map theory. (Recall that the separatrix maps describe the motion near the separatrices of a nonlinear resonance.) The analytical estimates of the Lyapunov times are compared to known numerical ones, i.e., to known estimates obtained by means of numerical integration of the orbits.

We review the properties of massive Population III and very metal-poor stars, including briefly their formation, IMF, their main sequence evolution, possible mass loss mechanisms, atmosphere modeling etc. For detailed predictions concerning the properties of these stars we refer to Schaerer (2002) and Schaerer (2002) and references therein. Extending these calculations, Schaerer (2007) present new calculations concerning the ionizing power, Ly-α strength and related properties for different metallicities as well as for a range of power-law and log-normal IMFs. For illustrations from these studies see the Figures below. New detailed calibrations for solar metallicity O-type stars have recently been presented by Martins et al. (2005).

Molecular gas has now been detected in 15 z>2 QSOs. These detections are commonly obtained by observing high–J CO transitions due to their relatively high peak fluxes and observing frequencies in the millimeter atmospheric windows. However, only observations of the CO ground-state transition, CO(1–0), have the potential to trace the molecular gas at lower excitations, which may give a better estimate of the total molecular gas mass of high–z QSOs. Here we present first z>4 CO(1–0) observations obtained with the NRAO Green Bank Telescope and the MPIfR Effelsberg telescope (Riechers et al. 2006). With these two 100m telescopes, we detect the CO(1–0) transition in the high–redshift QSOs BR 1202-0725 (z = 4.7), PSS J2322+1944 (z = 4.1), and APM 08279+5255 (z = 3.9). We find that the CO/FIR luminosity ratios of these high-z sources follow the same trend as seen for low-z galaxies. Utilizing large velocity gradient (LVG) models based on previous results for higher–J CO transitions, we derive that all CO emission can be described by a single gas component and that all molecular gas appears to be concentrated in a compact nuclear region. We thus find no evidence for luminous, extended CO(1–0) components in the molecular gas reservoirs around our target quasars.

We present a brief summary of Subaru observations of high-z galaxies. We discuss our future plan to probe galaxies beyond z = 10.

A significant fraction of Virgo cluster early-type dwarf galaxies have blue central colours caused by recent or ongoing star formation. A spectral analysis shows that even in their centers, stellar mass is dominated by an old population. These galaxies are an unrelaxed cluster population that possibly formed from morphological transformation of late-type galaxies.

If one strives for a reliable description of “Turbulent Mixing in Stars” one must account for a large variety of physical processes. These include non-locality, that is needed in unstably stratified regimes, overshooting, which occurs in a stably stratified regime, double-diffusion processes (semi-convection and salt-fingers), transport of angular momentum, the Li7 problem, compressibility, and magnetic fields. While phenomenological models are manifestly inadequate, LES are too computer intensive to tackle this large variety of processes. Since the requirement of completeness of the description of these processes must also result in models that are usable in stellar structure-evolution codes, we conclude that only the RSM (Reynolds Stress Model) can do so and a description of the state of the art in that field is presented in Part 2.

We observed embedded super-star clusters (SSCs) in blue compact dwarf galaxies (BCDs) IIZw40 and He2-10 with N-band and Q-band imaging and spectroscopy using the Cooled Mid-Infrared Camera and Spectrometer (COMICS) on board the 8m Subaru Telescope. Our infrared images of Henize 2–10 resolve the radio knots (knots I-V; Kobulnicky & Johnson 1999) and the N- and Q-band spectra show the strong [NeII] 12.8 μm and the [SIII] 18.71 μm together with relatively weak [SIV] 10.51 μm and [ArIII] 8.99 μm as well as the distinct unidentified infrared (UIR) bands at 8.6, 11.2 and 12.7 μm. We find the typical stellar spectral type of the members in the SSCs is O9 using the CoStar model (Stasinska & Schaerer 1997) and that the ionization environment in the most deeply embedded SSC(POS/#D) is the softest among those SSCs. The UIR bands exhibit a flat distribution over the galaxy and do not show a correlation with the MIR continuum, suggesting that polycyclic aromatic hydrocarbons (PAHs) are not strongly associated with the SSCs. We also find a possible decrease in the UIR 12.7 μm/11.2 μm ratio inside the embedded SSCs, suggesting that smooth-edged large PAHs are dominant (Hony et al. 2001) there. The small UIR to continuum ratio inside the embedded SSCs also suggests that the size distribution of the carbonaceous dust is skewed to the larger ones inside the embedded SSCs. Possible destruction of smaller species by harsh radiation field in the vicinity of massive stars due to the smaller heat capacity and/or the coagulation process that have been undertaken in dense dusty embedded SSCs would explain our results consistently. From the mid-infrared spectroscopy of IIZw40, the UIR bands are detected only in the south-western border of the mid-infrared peaks, suggesting the uneven distribution of PAHs within 4×106yr (Vanzi et al. 1996) after the nuclear starburst triggered in the merging of two small original galaxies.

The far-ultra violet (6 – 13.6 eV) photons from the OB stars in Ultra-compact HII regions (UCHs) produce photo-dissociation regions (PDRs) at the interface between the ionized and the natal molecular material. In this paper, we show that carbon recombination lines (CRLs) at frequencies greater than a few GHz are detectable from these PDRs and such observations can be used to: (1) estimate the physical properties of the PDR material; (2) study the kinematics of the PDR material relative to the HII region gas; (3) constrain the magnetic fields in the vicinity of UCHs and (4) address the lifetime problem of UCHs.

We test the evolution of the correlation between black hole mass and bulge properties, using a carefully selected sample of 20 Seyfert 1 galaxies at z=0.36 ±0.01. We estimate black hole mass from the Hβ line width and the optical luminosity at 5100 Å, based on the empirically calibrated photo-ionization method. Velocity dispersion are measured from stellar absorption lines around Mgb (5175 Å) and Fe (5270 Å) using high S/N Keck spectra, and bulge properties (luminosity and effective radius) are measured from HST images by fitting surface brightness. We find a significant offset from the local relations, in the sense that bulge sizes were smaller for given black hole masses at z=0.36 than locally. The measured offset is Δ M•=0.62 ± 0.10, 0.45 ±0.13, 0.59 ±0.19, respectively for M•–σ, M•–Lbulge, and M•–Mbulge relations. At face value, this result implies a substantial growth of bulges in the last 4 Gyr, assuming that the local M•–bulge property relation is the universal evolutionary end-point. This result is consistent with the growth of black holes predating the final growth of bulges at these mass scales (〈σ〉=170 km s−1).

The large numbers of nucleus fragments observed are a spectacular illustration of the process of cascading fragmentation in progress, a concept introduced to interpret the properties of the Kreutz system of sungrazers and comet D/1993 F2. The objective is to describe the fragmentation sequence and hierarchy of comet 73P, the nature of the fragmentation process and observed events, and the expected future evolution of this comet. The orbital arc populated by the fragments refers to an interval of 3.74 days in the perihelion time. This result suggests that they all could be products (but not necessarily first-generation fragments) of two 1995 events, in early September (involving an enormous outburst) and at the beginning of November. The interval of perihelion times is equivalent to a range of about 2.5 m/s in separation velocity or 0.00012 the Sun's attraction in nongravitational deceleration. Their combined effect suggests minor orbital momentum changes acquired during fragmentation and decelerations compatible with survival over two revolutions about the Sun. Fragment B is a likely first-generation product of one of the 1995 events. From the behavior of the primary fragment C, 73P is not a dying comet, even though fragment B and others were episodically breaking up into many pieces. Each episode began with the sudden appearance of a starlike nucleus condensation and a rapidly expanding outburst, followed by a development of jets, and a gradual tailward extension of the fading condensation, until the discrete masses embedded in it could be resolved. In April-May, this debris traveled first to the southwest, but models show their eventual motion toward the projected orbit. Fainter fragments were imaged over limited time, apparently because of their erratic activity (interspersed with periods of dormancy) rather than improptu disintegration. A dust trail joining the fragments and reminiscent of comet 141P/Machholz suggests that cascading fragmentation exerts itself profoundly over an extremely broad mass range of particulate debris.

We present preliminary results for six spiral galaxies from a sample of 25, where we have used the method developed by González & Graham (1996) to search for and analyze azimuthal color gradients across spiral arms. The six galaxies analyzed here are NGC 1703 (SBrb), NGC 3001 (SABrsbc), NGC 3059 (SBrsbc), NGC 3513 (SBrsc), NGC 4593 (RSBrsb), and NGC 4603 (SAsc).

NGC 1703: We found one azimuthal color gradient in NGC 1703. Star formation was traced with the reddening free parameter Q, and the dust lane was located with the (g – J) color. This gradient lies at a distance of 1.45 kpc from the center of the galaxy. In order to get some physical parameters of the star formation processes that are taking place in the spiral arms of the galaxies in our sample, we compared the observed Q profiles with the stellar population synthesis models of Bruzual & Charlot (2003). The fitted Q model is shown in figure 1. If one assumes that stars form in the site of the shock, and that they age as they move away from this birthsite, then distance from the dust lane (at constant radius) parameterizes stellar age. In fact, stretching the model Q to the fit the data fixes the ratio between the distance and the age of the stellar population. If, in addition, the rotational velocity is known, it is possible to find the angular velocity of the spiral pattern. The spiral pattern speeds derived from the gradients (under the assumption that star formation is triggered by the density wave) yield theoretical resonance positions that are coincident with the observed spiral end points, in 3 out of 6 spirals. It would be hard to avoid the conclusion that disk dynamics and star formation are fundamentally related in these objects.

Since 1990, the United Nations has held an annual workshop on basic space science for the benefit of the worldwide development of astronomy. Additional to the scientific benefits of the workshops and the strengthening of international cooperation, the workshops lead to the establishment of astronomical telescope facilities through the Official Development Assistance (ODA) of Japan. Teaching material, hands-on astrophysics material, and variable star observing programmes had been developed for the operation of such astronomical telescope facilities in the university environment. This approach to astronomical telescope facility, observing programme, and teaching astronomy has become known as the basic space science TRIPOD concept. Currently, a similar TRIPOD concept is being developed for the International Heliophysical Year 2007, consisting of an instrument array, data taking and analysis, and teaching space science.

The Teff location of Pre-Main Sequence (PMS) evolutionary tracks depends on the treatment of over-adiabaticity. We present here the PMS evolutionary tracks computed by using the mixing length theory of convection (MLT) in which the αMLT = l/Hp parameter calibration is based on 2D–hydrodynamical models (Ludwig et al. 1999). These MLT–α2D stellar models and tracks are very similar to those computed with non–grey ATLAS9 atmospheric boundary conditions and Full Spectrum of Turbulence (FST) convection model both in the atmosphere and in the interior. As for the FST models, the comparison of the new tracks with the location on the HR diagram of pre–MS binaries is not completely satisfactory; and the pre–MS lithium depletion in the MLT–α2D tracks is still much larger than that expected from the observations of lithium in young open clusters. Thus, in spite of the fact that 2D RHD models should provide a better convection description than any local model, their introduction is not sufficient to reconcile theory and observations. Lithium depletion in young clusters points towards a convection efficiency which, in pre–MS, should be smaller than in the MS.