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Selected AbstractsGEMINI 3D spectroscopy of BAL + IR + Fe ii QSOs , I. Decoupling the BAL, QSO, starburst, NLR, supergiant bubbles and galactic wind in Mrk 231MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2009S. Lipari ABSTRACT In this paper we present the first results of a study of BAL QSOs (at low and high redshift), based on very deep Gemini GMOS integral field spectroscopy. In particular, the results obtained for the nearest BAL IR,QSO Mrk 231 are presented. For the nuclear region of Mrk 231, the QSO and host galaxy components were modelled, using a new technique of decoupling 3D spectra. From this study, the following main results were found: (i) in the pure host galaxy spectrum an extreme nuclear starburst component was clearly observed, as a very strong increase in the flux, at the blue wavelengths; (ii) the BAL system I is observed in the spectrum of the host galaxy; (iii) in the clean/pure QSO emission spectrum, only broad lines were detected. 3D GMOS individual spectra (specially in the near-infrared Ca ii triplet) and maps confirm the presence of an extreme and young nuclear starburst (8 < age < 15 Myr), which was detected in a ring or toroid with a radius r= 0.3 arcsec , 200 pc, around the core of the nucleus. The extreme continuum blue component was detected only to the south of the core of the nucleus. This area is coincident with the region where we previously suggested that the galactic wind is cleaning the nuclear dust. Very deep 3D spectra and maps clearly show that the BAL systems I and II , in the strong ,absorption lines' Na iD,5889,95 and Ca ii K,3933 , are extended (reaching ,1.4,1.6 arcsec , 1.2,1.3 kpc, from the nucleus) and clearly elongated at the position angle (PA) close to the radio jet PA, which suggest that the BAL systems I and II are ,both' associated with the radio jet. The physical properties of the four expanding nuclear bubbles were analysed, using the GMOS 3D spectra and maps. In particular, we found strong multiple LINER/OF emission-line systems and Wolf,Rayet features in the main knots of the more external super bubble S1 (r= 3.0 kpc). The kinematics of these knots , and the internal bubbles , suggest that they are associated with an area of rupture of the shell S1 (at the south-west). In addition, in the more internal superbubble S4 and close to the core of the nucleus (for r < 0.7 arcsec , 0.6 kpc), two similar narrow emission-line systems were detected, with strong [S ii] and [O i] emission and ,V,,200 km s,1. These results suggest that an important part of the nuclear NLR is generated by the OF process and the associated low-velocity ionizing shocks. Finally, the nature of the composite BAL systems and very extended OF process , of 50 kpc , in Mrk 231 (and similar QSOs) are discussed. In addition, the ,composite hyperwind scenario' (already proposed for BALs) is suggested for the origin of giant Ly, blobs. The importance of study the end phases of Mrk 231, and similar evolving elliptical galaxies and QSOs (i.e. galaxy remnants) is discussed. [source] Structure and dynamics of galaxies with a low surface-brightness disc , I. The stellar and ionized-gas kinematicsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2008A. Pizzella ABSTRACT Photometry and long-slit spectroscopy are presented for a sample of six galaxies with a low surface-brightness stellar disc and a bulge. The characterizing parameters of the bulge and disc components were derived by means of a two-dimensional photometric decomposition of the images of the sample galaxies. Their surface-brightness distribution was assumed to be the sum of the contribution of a Sérsic bulge and an exponential disc, with each component being described by elliptical and concentric isophotes of constant ellipticity and position angle. The stellar and ionized-gas kinematics were measured along the major and minor axes in half of the sample galaxies, whereas the other half was observed only along two diagonal axes. Spectra along two diagonal axes were obtained also for one of the objects with major and minor axis spectra. The kinematic measurements extend in the disc region out to a surface-brightness level ,R, 24 mag arcsec,2, reaching in all cases the flat part of the rotation curve. The stellar kinematics turns out to be more regular and symmetric than the ionized-gas kinematics, which often shows the presence of non-circular, off-plane and non-ordered motions. This raises the question about the reliability of the use of the ionized gas as the tracer of the circular velocity in the modelling of the mass distribution, in particular in the central regions of low surface-brightness galaxies. [source] VLT/SINFONI integral field spectroscopy of the Super-antennae,MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2007J. Reunanen ABSTRACT We present the results of H - and K -band very large telescope/Spectrograph for INtegral Field Observations in the Near Infrared (VLT/SINFONI) integral field spectroscopy of the Ultraluminous Infrared Galaxy (ULIRG) IRAS 19 254,7245 (the Super-antennae), an interacting double galaxy system containing an embedded active galactic nuclei. Deep K -band spectroscopy reveals Pa, arising in a warped disc with position angle of 330° and an inclination i= 40°,55°. The kinemetric parameters derived for H2 are similar to Pa,. Two high-ionization emission lines, [Si vi] and [Al ix], are detected and we identify as [Ni ii] the line observed at 1.94 ,m. Diluting non-stellar continuum, which was previously detected, has decayed, and the H -band continuum emission is consistent with pure stellar emission. Based on H2 emission-line ratios, it is likely that at the central 1-kpc region H2 is excited by ultraviolet fluorescence in dense clouds while shock excitation is dominant further out. This scenario is supported by very low Pa, to H2 line ratio detected outside the nuclear region and non-thermal ortho/para ratios (,2.0,2.5) close to the nucleus. [source] Structural parameters of Mayall II = G1 in M31MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2007J. Ma ABSTRACT Mayall II = G1 is one of the most luminous globular clusters (GCs) known in M31. New deep, high-resolution observations with the Advanced Camera for Surveys on the Hubble Space Telescope are used to provide accurate photometric data to the smallest radii yet. In particular, we present the precise variation of ellipticity and position angle, and of surface brightness for the core of the object. Based on these accurate photometric data, we redetermine the structural parameters of G1 by fitting a single-mass isotropic King model. We derive a core radius, rc= 0.21 ± 0.01 arcsec (= 0.78 ± 0.04 pc), a tidal radius, rt= 21.8 ± 1.1 arcsec (= 80.7 ± 3.9 pc), and a concentration index c= log (rt/rc) = 2.01 ± 0.02. The central surface brightness is 13.510 mag arcsec,2. We also calculate the half-light radius, at rh= 1.73 ± 0.07 arcsec (= 6.5 ± 0.3 pc). The results show that, within 10 core radii, a King model fits the surface brightness distribution well. We find that this object falls in the same region of the MV versus log Rh diagram as , Centauri, M54 and NGC 2419 in the Milky Way. All three of these objects have been claimed to be the stripped cores of now defunct dwarf galaxies. We discuss in detail whether GCs, stripped cores of dwarf spheroidals and normal dwarf galaxies form a continuous distribution in the MV versus log Rh plane, or if GCs and dwarf spheroidals constitute distinct classes of objects; we present arguments in favour of this latter view. [source] Space very long baseline interferometry observations of polarization in the jet of 3C 380MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2006A. Papageorgiou ABSTRACT A comparison between low-frequency space very long baseline interferometry (VLBI) and high-frequency ground-based VLBI images can, in principle, be used to detect small variations in rotation measure (RM) on fine angular scales inaccessible to ground arrays alone. This paper reports an attempt to perform such a comparison using the jet in the quasar 3C 380. Observations made with the VSOP antenna HALCA together with a ground array at wavelength 1.6 GHz provide total intensity and polarization images of comparable resolution to those from the ground array alone at 5 GHz. The results provide an image showing derotated magnetic vector position angle of somewhat higher resolution than that available earlier. The results show variations in an RM around component A of the order of 10 rad m,2 that could not have been detected with the ground array alone. It is concluded that satellite VLBI observations provide a promising means to study the distribution of matter and magnetic fields around parsec-scale jets. The ground observations used here follow the steady outward drift of component A, which has approximately doubled its distance from the core since the first observations in 1982. They also reveal total intensity and polarization structure associated with a bright knot 0.7 arcsec from the core which is reminiscent of that expected for a conical shock wave. [source] Gemini near-infrared integral field spectroscopy of the narrow-line region of ESO 428,G14: kinematics, excitation and the role of the radio jetMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2006Rogemar A. Riffel ABSTRACT We present two-dimensional (2D) gas kinematics and excitation of the inner 300 pc of the Seyfert galaxy ESO 428,G14 at a sampling of 14 pc2, from near-infrared spectroscopic observations at R, 6000 obtained with the Integral Field Unit (IFU) of the Gemini Near-Infrared Spectrograph. From measurements of fluxes and profiles of the emission lines [Fe ii],1.257 ,m, Pa,, H2, 2.121 ,m and Br,, we construct 2D maps of line intensities and ratios, radial velocities and velocity dispersions. Emission line ,tomography' is provided by velocity slices obtained across the line profiles, a unique capability of IFUs, which allows the mapping of not only the peak velocities but including also the wings. We compare these maps with a previously published high spatial resolution radio map and find a tight relation between the radio structure and the emission-line flux distributions and kinematics, revealing that the radio jet plays a fundamental role not only in shaping the narrow-line region but also in the imprint of its kinematics. Blueshifts of up to 400 km s,1 and velocity dispersions of up to 150 km s,1 are observed in association with the radio jet at a position angle (PA) = 129°, which is also the PA of the photometric major axis of the galaxy. We conclude that the radio jet is launched at a small angle relative to the galactic plane, with the north-western side slightly oriented towards us. This angle is small enough for the radio jet to shock and compress the gas in the plane of the galaxy, and for the nuclear continuum to ionize and heat it. The distinct kinematics and flux distributions observed for the different emission lines suggest different origins for their emission. The [Fe ii] shows the largest blueshifts and velocity dispersions and its flux distribution is concentrated along the jet, while the H2 shows the lowest velocity dispersions and has additional flux contribution from regions beyond the jet. Both X-rays emitted by the active galactic nucleus and shocks produced by the radio jet can excite the H2 and [Fe ii] emission lines. We use the 2D velocity dispersion maps to estimate upper limits to the contribution of the radio jet to the excitation of [Fe ii] and H2 which may reach 90 per cent for [Fe ii] and 80 per cent for H2 in the jet region. The [Fe ii]/Pa, emission-line ratios and the association of the [Fe ii] flux distribution and kinematics with the radio structure support a stronger contribution of the radio jet to the [Fe ii] excitation than that of H2. In the regions beyond the jet, the observations favour X-ray excitation. [source] Discovery of large-scale methanol and hydroxyl maser filaments in W3(OH)MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2006L. Harvey-Smith ABSTRACT Images of the 6.7-GHz methanol maser emission from W3(OH) made at 50- and 100-mas angular resolution with the Multi-Element Radio-Linked Interferometer Network (MERLIN) are presented. The masers lie across the western face of the ultracompact H ii region in extended filaments which may trace large-scale shocks. There is a complex interrelation between the 6.7-GHz methanol masers and hydroxyl (OH) masers at 1.7 and 4.7 GHz. Together the two species trace an extended filamentary structure that stretches at least 3100 au across the face of the ultracompact H ii region. The dominant 6.7-GHz methanol emission coincides with the radio continuum peak and is populated by masers with broad spectral lines. The 6.7-GHz methanol emission is elongated at position angle 50° with a strong velocity gradient, and bears many similarities to the methanol maser disc structure reported in NGC 7538. It is surrounded by arcs of ground state OH masers at 1.7 GHz and highly excited OH masers at 13.44 GHz, some of which have the brightest methanol masers at their focus. We suggest that this region hosts the excitation centre for the ultracompact H ii region. [source] Infrared mergers and infrared quasi-stellar objects with galactic winds , III.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2005Mrk 231: an exploding young quasi-stellar object with composite outflow/broad absorption lines (and multiple expanding superbubbles) ABSTRACT We present a study of outflow (OF) and broad absorption line (BAL) systems in Mrk 231, and in similar infrared (IR) quasi-stellar objects (QSOs). This study is based mainly on one-dimensional and two-dimensional spectroscopy (obtained at La Palma/William Herschel Telescope, Hubble Space Telescope, International Ultraviolet Explorer, European Southern Observatory/New Technology Telescope, Kitt Peak National Observatory, Apache Point Observatory and Complejo Astronomico El Leoncito observatories) plus Hubble Space Telescope images. For Mrk 231, we report evidence that the extreme nuclear OF process has at least three main components on different scales, which are probably associated with: (i) the radio jet, at parsec scale; (ii) the extreme starburst at parsec and kiloparsec scale. This OF has generated at least four concentric expanding superbubbles and the BAL systems. Specifically, inside and very close to the nucleus the two-dimensional spectra show the presence of an OF emission bump in the blend H,+[N ii], with a peak at the same velocity of the main BAL-I system (VEjection BAL-I,,4700 km s,1). This bump was more clearly detected in the area located at 0.6,1.5 arcsec (490,1220 pc), to the south-west of the nucleus core, showing a strong and broad peak. In addition, in the same direction [at position angle (PA) ,,120°, i.e. close to the PA of the small-scale radio jet] at 1.7,2.5 arcsec, we also detected multiple narrow emission-line components, with ,greatly' enhanced [N ii]/H, ratio (very similar to the spectra of jets bow shocks). These results suggest that the BAL-I system is generated in OF clouds associated with the parsec-scale jet. The Hubble Space Telescope images show four (or possibly five) nuclear superbubbles or shells with radii r, 2.9, 1.5, 1.0, 0.6 and 0.2 kpc. For these bubbles, the two-dimensional H, velocity field map and two-dimensional spectra show the following. (i) At the border of the more extended bubble (S1), a clear expansion of the shell with blueshifted velocities (with circular shape and at a radius r, 5.0 arcsec). This bubble shows a rupture arc , to the south , suggesting that the bubble is in the blowout phase. The axis of this rupture or ejection (at PA , 00°) is coincident with the axis of the intermediate and large-scale structures detected at radio wavelengths. (ii) In addition, in the three more external bubbles (S1, S2, S3), the two-dimensional William Herschel Telescope spectra show multiple emission-line components with OF velocities, of ,VOF Bubble, S1, S2 and S3 =[,(650 , 420) ± 30], [,500 ± 30] and [,230 ± 30] km s,1. (iii) In the whole circumnuclear region (1.8 < r < 5 arcsec), the [N ii]/H, and [S ii]/H, narrow emission-line ratios show high values (>0.8), which are consistent with low-ionization nuclear emission-line region/OF processes associated with fast velocity shocks. Therefore, we suggest that these giant bubbles are associated with the large-scale nuclear OF component, which is generated , at least in part , by the extreme nuclear starburst: giant supernova/hypernova explosions. The variability of the short-lived BAL-III Na i D system was studied, covering almost all the period in which this system appeared (between ,1984 and 2004). We have found that the BAL-III light curve is clearly asymmetric with a steep increase, a clear maximum and an exponential fall (similar to the shape of a supernova light curve). The origin of this BAL-III system is discussed, mainly in the framework of an extreme explosive event, probably associated with giant supernova/hypernova explosions. Finally, the IR colour diagram and the ultraviolet BAL systems of IR + GW/OF + Fe ii QSOs are analysed. This study shows two new BAL IR QSOs and suggests/confirms that these objects could be nearby young BAL QSOs, similar to those detected recently at z, 6.0. We propose that the phase of young QSOs is associated with accretion of a large amount of gas (by the supermassive black hole) + extreme starbursts + extreme composite OFs/BALs. [source] Spectropolarimetry of the 3-,m water-ice feature towards young stellar objectsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2002R. P. Holloway Abstract We present spectropolarimetry of the 3-,m water-ice feature towards five young stellar objects embedded in molecular clouds, including the Becklin,Neugebauer object, with wavelength range and spectral resolution much improved over previous studies. There is ice-feature polarization excess in four of the five sources and our observations indicate that the polarization is caused by the dichroic absorption of aligned grains in at least three of these. The ice-feature polarization excess is always accompanied by a systematic variation in the position angle of polarization, indicating that the ice-mantled grains are fractionated in the line of sight through a changing magnetic-field orientation. The results are compared with a recently published mid-infrared survey and we find good correlations between the polarization of the 3-,m ice feature and the 10-,m silicate feature, compelling evidence for the presence of water-ice mantled silicate grains, and which suggests that the core/mantle ratio does not differ widely between objects, an important result for grain models. [source] VSOP polarization observations of the BL Lacertae object OJ 287MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2001D. C. Gabuzda VLBI total intensity and linear polarization images of the BL Lacertae object OJ 287 have been obtained at using a global ground array and the HALCA orbiting antenna, and at two weeks earlier using the VLBA. In the ground-based 6-cm images, the source is dominated by a core,jet double structure the components of which are essentially unresolved. The baselines to the orbiting antenna resolve both of these compact components. In the VSOP images, the ground-based ,core' breaks up into several distinct components, demonstrating that this region is dominated by the contribution of bright, optically thin knots of jet emission. A very similar structure is observed in the 1.3-cm image. The magnetic field in the core is transverse, becomes longitudinal in the inner jet, then makes a sharp transition to a region of transverse field further from the core. This suggests that the field in the outer jet has become highly ordered in the transverse direction owing to the action of a shock; the physical nature of the extended region of longitudinal field closer to the core is not clear. The availability of nearly simultaneous observations with comparable resolution at widely spaced frequencies enabled detection of a ,90° rotation in polarization position angle for the core, owing to the transition from the optically thick (6 cm) to the optically thin (1.3 cm) regime. [source] Projected properties of triaxial modified Hubble mass modelsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2000D. K. Chakraborty The projected properties of a triaxial generalization of the modified Hubble mass model are investigated. The projected surface density can be evaluated analytically, allowing us to investigate its properties in analytic forms. The profiles of axis ratio and position angle of the major axis of constant density elliptical contours, as a function of viewing angles, can be compared with observations. [source] Drag-gravity torques on galaxies in clusters: radial small-scale alignment effectsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY: LETTERS (ELECTRONIC), Issue 1 2010Alejandro González-Sánchez ABSTRACT We calculate the torque on galaxies in clusters due to gravity and to dynamical friction forces in order to study the possible origin of small-scale alignment effects as the result of interactions with their environment. The equation of motion for the position angle of a galaxy is derived by using a simple model. We find that weak radial alignment effects can be produced by this mechanism involving only the most massive galaxies. We also introduce a dependence on the cluster eccentricity to our equations in order to explore the alignment of galaxies with the cluster's major axis. We find that in the inner regions of high eccentricity clusters, alignments of massive galaxies with the cluster's major axis dominate over the radial ones. This mechanism could account for the observed alignment effects of the most massive galaxies with the major axis of their host cluster. Our results suggest that dynamical friction is a viable generator of alignment only for the most massive cluster galaxies. For the observed alignments of normal galaxies a primordial origin has to be explored. [source] Estimation of Phosphene Spatial Variability for Visual Prosthesis ApplicationsARTIFICIAL ORGANS, Issue 5 2010Iyad Obeid Abstract Visual prostheses are the focus of intensive research efforts to restore some measure of useful vision to blind or near-blind patients. The development of such technology is being guided to an extent by tools that simulate prosthesis behavior for healthy sighted subjects in order to assess system requirements and configurations. These simulators, however, typically assume purely deterministic phosphene properties and thus do not apply any variability to phosphene size, intensity, or location. We address this issue by presenting data on phosphene variability measured in a blind human subject fitted with an optic nerve prosthesis. In order to correct for normal limitations in human-pointing accuracy, the experimental conditions were repeated with sighted subjects. We conclude that identical optic nerve stimulations can result in phosphenes whose perceived locations vary by up to 5° of deviation angle and 10° of position angle. The consistency of phosphenes presented in the peripheral field of view can vary by an additional 3°. [source] Biases in the polarization position angles in the NRAO-VLA sky survey point source catalogueMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2008R. A. Battye ABSTRACT We have examined the statistics of the polarization position angles determined for point sources in the NRAO-VLA Sky Survey (NVSS), and find that there is a statistically significant bias towards angles which are multiples of 45°. The formal probability that the polarization angles are drawn from a uniform distribution is exponentially small. When the sample of those NVSS sources with polarizations detected with a signal-to-noise ratio ,3 is split either around the median polarized flux density or the median fractional polarization, the effect appears to be stronger for the more highly polarized sources. Regions containing strong sources and regions at low-Galactic latitudes are not responsible for the non-uniform distribution of position angles. We identify clean bias as the probable cause of the dominant effect, coupled with small multiplicative and additive offsets on each of the Stokes parameters. Our findings have implications for the extraction of science, such as information concerning galactic magnetic fields, from large-scale polarization surveys. [source] Morphology, kinematics and modelling of the elliptical planetary nebula Sa 2-21MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2003D. J. Harman ABSTRACT The little studied PN, Sa 2-21 has been observed using the Manchester echelle spectrometer at the Anglo-Australian telescope. Narrow band, long-slit spectra were obtained at six positions over two perpendicular position angles in both the [N ii],6584 Ĺ and [O iii],5007 Ĺ emission lines. An [O iii] halo has been detected for the first time. A morphological modelling program was used to help determine the geometry, structure and kinematics of this ellipsoidal PN. It is proposed that the structure includes a pair of mid-latitude rings of [N ii] emission, not previously seen in elliptical PNe. Radial spokes of [O iii] emission have been detected in the main nebular shell indicating the presence of dynamical instabilities. [source] Speckle observations with PISCO in Merate: VIII.ASTRONOMISCHE NACHRICHTEN, Issue 3 2010Astrometric measurements of visual binaries in 200, new orbits of the multiple system Zeta Aqr Abstract We present relative astrometric measurements of visual binaries made during the second semester of 2007, with the speckle camera PISCO at the 102 cm Zeiss telescope of Brera Astronomical Observatory, in Merate. Our sample contains orbital couples as well as binaries whose motion is still uncertain. We obtained 283 new measurements of 279 objects, with angular separations in the range 0,.17,4,.4, and an average accuracy of 0,.014. The mean error on the position angles is 0°.6. Most of the position angles were determined without the usual 180° ambiguity with the application of triple-correlation techniques and/or by inspection of the long integration files. We also present the new orbit we have computed for Zeta Aqr AB (ADS 15971), for which our measurements lead to large residuals with the previously computed orbit. We were also able to compute the elements of the perturbation orbit Bb-P caused by an invisible companion, whose mass is estimated at 0.7 M, (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Speckle observations with PISCO in Merate: VI.ASTRONOMISCHE NACHRICHTEN, Issue 1 2009Astrometric measurements of visual binaries in 200 Abstract We present relative astrometric measurements of visual binaries made during the second semester of 2006, with the speckle camera PISCO at the 102 cm Zeiss telescope of Brera Astronomical Observatory, in Merate. Our sample contains orbital couples as well as binaries whose motion is still uncertain. We obtained 175 new measurements of 169 objects, with angular separations in the range 0,.1,4,.2, and an average accuracy of 0,.01. The mean error on the position angles is 0°.6. Most of the position angles could be determined without the usual 180° ambiguity with the application of triplecorrelation techniques and/or by inspection of the long integration files. We also present the new orbits we have computed for ADS 11479, 11584 and 16538, for which our measurements lead to large residuals and/or for which the revision was justified by the significant number of observations made since the last orbit computation (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||