We have performed CO(J=3−2) emission observations with the Atacama Submillimeter Telescope Experiment (ASTE) toward the 5′ × 5′ (or 6.6 × 6.6 kpc at the distance D = 4.5 Mpc) region of the nearby barred spiral galaxy M 83. We successfully resolved the major structures, i.e., the nuclear starburst region, bar, and inner spiral arms in CO(J=3−2) emission at a resolution of 22'' (or 480 pc), showing a good spatial coincidence between CO(J=3−2) and 6 cm continuum emissions.

From a comparison of CO(J=3−2) data with CO(J=1−0) intensities measured with Nobeyama 45-m telescope, we found that the radial profile of CO(J=3−2)/CO(J=1−0) integrated intensity ratio R3−2/1−0 is almost unity in the central region (r<0.25 kpc), whereas it drops to a constant value, 0.6–0.7, in the disk region. The radial profile of star formation efficiencies (SFEs), determined from 6 cm radio continuum and CO(J=1−0) emission, shows the same trend as that of R3−2/1−0. At the bar-end (r ~ 2.4 kpc), the amounts of molecular gas and the massive stars are enhanced when compared with other disk regions, whereas there is no excess of R3−2/1−0 and SFE in that region. This means that a simple summation of the star forming regions at the bar-end and the disk cannot reproduce the nuclear starburst of M 83, implying that the spatial variation of the dense gas fraction traced by R3−2/1−0 governs the spatial variation of SFE in M 83.

Emission-line observations made with the Spitzer Space Telescope are used to test the predicted ionizing spectral energy distributions of various stellar atmosphere models.

The particle reaceleration model is one of the most promising possibilities to explain the Mpc-scale diffuse radio emission detected in a number of galaxy clusters. Ongoing and future radio observations at low frequencies may help in constraining and testing this model.

We have kept optical monitoring of a peculiar black hole X-ray binary, V4641 Sgr. Based on our observations, we show that its unprecedented activity can be divided into 5 phases. In this paper, we report their observational properties.

We study nearby X-ray-emitting dusty elliptical galaxies in mid- and far-infrared by using the Spitzer Space Telescope and AKARI, the Japanese infrared astronomical satellite.

Secular evolution theory predicts that spheroidal components are formed thanks to bars that can transport gas to the central regions of the galaxies. This activity would trigger the star formation needed to generate galactic bulges. According to this idea, bars at smaller scales may carry material to the galactic center and feed active galactic nuclei. For the first time, we have carried out a complete kinematical and stellar population analysis of a double-barred galaxy (NGC 357) to determine if this system of two bars is efficient enough to cause that kind of effects. We have measured suitable line-strength indices on high quality spectra to obtain the relative ages and metallicities for the different structural components and thus constrain the star formation history. First results seems to indicate that in the case of NGC 357 the nuclear bar hasn't played an important role in fueling the star formation in the center.

We study giant radio sources at long wavelengths.

The formation and evolution of planetary nebulae (PNe) is largely attributed to the interaction of the fast stellar wind with the wind of the Asymptotic Giant Branch (AGB), and to the dynamical effects of the photo-ionization of the nebular material. The physical structure of a PN can be used to assess the relative importance of fast stellar winds and photo-ionization in its shaping and evolution, but there is little information on the hot gas content of PNe. Using our recent XMM-Newton observations of NGC 3242, we have made a comprehensive analysis of the physical structure of this nebula, combining the physical conditions of the shocked fast stellar wind in its interior and the spatio-dynamical structure and physical conditions of the photo-ionized material.

Historical records of the Nile water level provide a unique opportunity to investigate the possibility that solar variability influences the Earth's climate. Particularly important are the annual records of the water level, which are uninterrupted for the years 622–1470 A.D. These records are non-stationary, so that standard spectral analyses cannot adequately characterize them. Here the Empirical Mode Decomposition technique, which is designed to deal with non-stationary, nonlinear time series, becomes useful. It allows the identification of two characteristic time scales in the water level data that can be linked to solar variability: the 88 year period and a time scale of about 200 years. These time scales are also present in the concurrent aurora data. Auroras are driven by coronal mass ejections and the rate of auroras is an excellent proxy for solar variabiliy. Analysis of auroral data contemporaneous with the Nile data shows peaks at 88 years and about 200 years. This suggests a physical link between solar variability and the low-frequency variations of the Nile water level. The link involves the influence of solar variability on the North Annual Mode of atmospheric variability and its North Atlantic and Indian Oceans patterns that affect rainfall over Eastren Equatorial Africa where the Nile originates.

We present preliminary long-slit spectroscopy of a sample of nearby cD galaxies recently observed with the William Herschel and GEMINI North and South Telescopes. So far, we have accumulated data for 27 cDs. More is being observed with the GEMINI telescopes, to create a statistically significant sample. Unresolved stellar populations will be used to investigate the history of when stars formed in these galaxies. Central and spatially resolved line strengths measured from these high signal-to-noise data will be interpreted via population modelling and used to derive luminosity weighted average ages and abundances. Comparison with previous results from other Hubble types of galaxies will highlight relative differences in their evolution.

OH masers are sensitive probes of the kinematics and physical conditions, and give unique information on the magnetic field through their polarization. Zeeman splitting of the OH lines can give the magnetic field strength and direction. Observing OH masers with MERLIN we studied the bipolar outflow in the star-forming region ON1, which hosts one of the earliest known ultra-compact (UC) HII regions. The strongest masers lie near the southern edge of the UCHII region in an elongated distribution. The maser distribution is orthogonal to the bipolar outflow seen in HCO+, suggesting that the OH masers may be embedded in a molecular disk or torus around a young B0.3 star, most likely tracing a shock front. An isolated group of 1720-MHz masers is also seen to the East. The magnetic field deduced from Zeeman splitting of the OH maser lines shows a large-scale order, with field values ranging from -0.4 to -4.6 mG. These results add to the growing body of evidence for OH masers associated with molecular disks or tori at the centre of bipolar outflow from massive young stars, and for a significant role played by the magnetic field in generating or channeling the bipolar outflow. Further details are presented by Nammahachak et al. 2006.

We present an investigation of the metal enrichment of the intra-cluster medium (ICM) by galactic winds and merger-driven starbursts. We use combined N-body/hydrodynamic simulations with a semi-numerical galaxy formation model. The inhomogeneities in the metal distribution caused by these processes are an ideal tool to reveal the dynamical state of a galaxy cluster. We show that X-ray weighted metal maps distinguish between pre- or post-merger galaxy clusters by comparing the metallicity distribution with the galaxy-density distribution: pre-mergers have a metallicity gap between the subclusters, post-mergers a high metallicity between subclusters.

Many galactic nuclei contain disks of gas and possibly stars surrounding a supermassive black hole. These disks may play a key role in the evolution of galactic centers. Here we address the problem of finding stable warped equilibrium configurations for such disks, considering the attraction by the black hole and the disk self-gravity as the only acting forces. We model these disks as a collection of concentric, circular rings.

We find the equilibria of such systems of rings, and determine how they scale with the ring parameters and the mass of the central black hole. We show that in some cases these disk equilibria may be highly warped. We then analyze the stability of these disks, using both direct time integration and linear stability analysis. This shows that the warped disks are stable for a range of disk-to-black hole mass ratios, when the rings extend over a limited range of radii.

The spatial distributions of the mean luminosity-weighted stellar age, metallicity, and α/Fe ratio along both photometric axes of two nearby elliptical galaxies have been obtained using Lick index measurements on long slit spectra in order to reconstruct the star formation history in their kinematically distinct subsystems. Lick indexes were compared with those of single-aged stellar population (SSP) models. A population synthesis method was also applied in order to help disentangling the age-metallicity degeneracy. The stars characteristics are associated with their kinematics: they are older and α-enhanced in the not rotating bulge of NGC 1052 and counter rotating core of NGC 7796, while they show a strong spread of α/Fe and age along the rotating disk of NGC 1052 and an outwards radial decreasing of them outside the core of NGC 7796.

We present slit-scan observations of the Hα and [NII] 6584 Å emission lines toward the HL Tau jet with the 8.2m Subaru Telescope. HL Tau is an active young star in transitional phase from an embedded class I protostar to a class II pre-main-sequence star, and it is located in the northeastern part of the L1551 dark cloud. The slit-scan technique at high spectral resolution (R=3.6×104) allowed for studying kinematics of individual features in unprecedented details. The Hα emission shows the main jet component (VLSR ~ −180 km s−1) and distinct lower velocity components (∣VLSR∣<120 km s−1). The [NII] emission is primarily associated with the jet within 10 arcsecond from the source, and also knot B and C ~30 arcsecond away from the source. These are associated with the main jet component, and absent in the lower velocity components. The velocity of Hα and [NII] emissions in the main jet component well matches each other.

Our high-resolution spectra do not show the evidence for the presence of turbulent mixing layers between the jet and surrounding gas. The lower velocity components are associated with individual knots, and explained as the lateral of bow shocks. Their line profiles suggest that shock velocity of the knots A-C is 120~130 km s−1 (Hartigan et al. 1987). The observed [NII]/Hα flux ratio markedly differ between regions: 0.1-0.7 in base of the jet; less than 0.1 in knot A; ~0.2 in knot B; ~0.4 in knot C; and ~0.7 in knot D. Shock models predict that the [NII]/Hα flux ratio reflects the ionization of the preshock gas. This results from enhancement of N+ via the charge exchange reaction (Osterbrock 1989; Bacciotti & Eislöffel 1999). We perform more detailed comparisons between models and observations (Hartigan et al. 1987; Morse et al. 1994). The base of the jet and knot D show high [NII]/Hα flux ratios, indicating that the ambient gas surrounding the jet is considerably ionized, or the preshock density of the ambient gas is significantly low. In contrast, the knots A-C exhibit low [NII]/Hα flux ratios, indicating that the ambient gas surrounding the jet is almost neutral, or the preshock density of the ambient gas is significantly high. The [NII]/Hα flux ratio increases from knot A (0.1) to knot D (~0.7). This suggests that the ionization fraction of the ambient gas increases away from the source, or the preshock density of the ambient gas decreases away from the source.

The formation and shaping of planetary nebulae (PNe) is probably the most exciting, yet least understood issue in the late evolution of (1–8) $M_{\odot}$ stars. PNe evolve from the envelopes of AGB stars through the supposedly very short ($\lesssim10^3$ yr) pre-PN (or PPN) phase (Balick & Frank 2002). In 1998, in a radical departure from the then long-standing theoretical paradigm for PN formation, Sahai & Trauger (1998) proposed that as most stars evolve off the AGB, they drive collimated fast winds that sweep up and shock the AGB circumstellar envelope, producing the observed dramatic changes in circumstellar geometry and kinematics from the AGB to the PN phase. Pre-Planetary Nebulae (PPNs) have traditionally been understood as rare objects that represent a transitory phase in the evolution of AGB stars to PNs. In recent years, mainly due to high-resolution imaging surveys with HST, it has become possible to start studying the detailed physical properties for a statistically significant number of these objects. Here we provide a brief report of results from our several large surveys of PPNs with HST (and supporting ground-based observations).

We present a unification model of the matter outflow from AGN. The model includes calculations of the hot gas dynamics, the dynamics of the cold clouds in the hot gas flow, and the radiation transfer in this two-phase medium. We used the model for calculation of the ultraviolet spectrum of the quasar q1303+308. The spectrum of this object is a well-know example of the line-locking effect. Our model calculations permits for the first time to obtain some thin details seen in the observed absorption spectrum, which confirms the validity of the main issues of our theory and model.

We have carried out deep BVR surface photometry of 6 cD and cD-like galaxies using the 2.1-m telescope at San Pedro Mártir, cD galaxies are supergiant galaxies (M>1013M⊙) with enormous halos (>100 kpc in radius) surrounding a giant elliptical galaxy, found generally at the centre of rich clusters (Oemler 1976, Schombert 1988). The surface brightness profiles of their halos (envelopes) break from the r1/4 law, containing more light at large radii (Schombert (1988)), although a detailed 1 and 2 dimensional analysis of their morphology has yet to be carried out. There have been four main theories as to the origin of cD envelopes (Schombert (1988) and references within), a) stripping of stars from other cluster member galaxies, b) formation of galaxy and envelope at the same time during the formation of the cluster, c) mergers of cluster members, which do not easily explain the high velocity dispersions in the envelopes (~ 1000 km s−1), d) cooling flows: accumulation of cooling X-ray-emitting ICM gas around the central galaxy. Very red envelopes have been found around some cD's, and star formation biased towards lowmass stars in cooling flows were invoked to explain these red halos, but the expected very bright near-IR halos were not detected (Joy et al. 1995 and references within). Previous detailed studies of cD galaxies (e.g. Mackie 1992) found a range of colour gradients.

Baily beads timings of annular eclipse of October 3, 2005 and total eclipse of March 29, 2006 have been analyzed for measuring a variation of the actual solar radius between those dates. After 1/3 of all beads events analyzed, corrections to average solar radius are known within $\pm$0.19”. High resolution video have been made at the boundaries of totality-annularity paths, to increase the number of beads visible. Comparison of observations made with different combinations of telescopes/filters/detectors is discussed.

I review the potential for observing cosmic re-ionization using the HI 21 cm line.