We present a multiwavelength investigation of a region of a nearby giant molecular cloud that is distinguished by a minimal level of star formation activity. With our new (CO)-C-12(J = 2-1) and (CO)-C-13(J = 2-1) observations of a remote region within the middle of the California molecular cloud, we aim to investigate the relationship between filaments, cores, and a molecular outflow in a relatively pristine environment. An extinction map of the region from Herschel Space Observatory observations reveals the presence of two 2 pc long filaments radiating from a highextinction clump. Using the (CO)-C-13 observations, we show that the filaments have coherent velocity gradients and that their mass-per-unit-lengths may exceed the critical value above which filaments are gravitationally unstable. The region exhibits structure with eight cores, at least one of which is a starless, prestellar core. We identify a low-velocity, low-mass molecular outflow that may be driven by a flat spectrum protostar. The outflow does not appear to be responsible for driving the turbulence in the core with which it is associated, nor does it provide significant support against gravitational collapse.

We present Gemini Planet Imager polarized intensity imagery of HD 100453 in Y, J, and K1 bands that reveals an inner gap (9-18 au), an outer disk (18-39 au) with two prominent spiral arms, and two azimuthally localized dark features that are also present in Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) total intensity images. Spectral energy distribution fitting further suggests that the radial gap extends to 1 au. The narrow, wedge-like shape of the dark features appears similar to predictions of shadows cast by an inner disk that is misaligned with respect to the outer disk. Using the Monte Carlo radiative transfer code HOCHUNCK3D, we construct a model of the disk that allows us to determine its physical properties in more detail. From the angular separation of the features, we measure the difference in inclination between the disks (45 degrees) and their major axes, PA = 140 degrees east of north for the outer disk, and 100 degrees for the inner disk. We find an outer-disk inclination of 25 degrees +/- 10 degrees from face-on, in broad agreement with the Wagner et al. measurement of 34 degrees. SPHERE data in J and H bands indicate a reddish disk, which indicates that HD 100453 is evolving into a young debris disk.

We combine precision radial velocity data from four different published works of the stars in the Leo II dwarf spheroidal galaxy. This yields a data set that spans 19 years, has 14 different epochs of observation, and contains 372 unique red giant branch stars, 196 of which have repeat observations. Using this multi-epoch data set, we constrain the binary fraction for Leo II. We generate a suite of Monte Carlo simulations that test different binary fractions using Bayesian analysis and determine that the binary fraction for Leo II ranges from 0.30(-0.10)(+0.09) to 0.34(-0.11)(+0.11), depending on the distributions of binary orbital parameters assumed. This value is smaller than what has been found for the solar neighborhood (similar to 0.4-0.6) but falls within the wide range of values that have been inferred for other dwarf spheroidals (0.14-0.69). The distribution of orbital periods has the greatest impact on the binary fraction results. If the fraction we find in Leo II is present in low-mass ultra-faints, it can artificially inflate the velocity dispersion of those systems and cause them to appear more dark matter rich than in actuality. For a galaxy with an intrinsic dispersion of 1 km s(-1) and an observational sample of 100 stars, the dispersion can be increased by a factor of 1.5-2 for Leo II-like binary fractions or by a factor of three. for binary fractions on the higher end of what has been seen in other dwarf spheroidals.

Using a sample of nearly half a million galaxies, intersected by over 7 million lines of sight from the Sloan Digital Sky Survey Data Release 12, we trace H alpha + [N II] emission from a galactocentric projected radius, r(p), of 5 kpc to more than 100 kpc. The emission flux surface brightness is alpha r(p) 1.9 +/- 0.4. We obtain consistent results using only the Ha or [N II] flux. We measure a stronger signal for the bluer half of the target sample than for the redder half on small scales, r(p) < 20 kpc. We obtain a 3 sigma detection of H alpha + [N II] emission in the 50-100 kpc r(p) bin. The mean emission flux within this bin is (1.10 +/- 0.35) x 10(-20) erg cm(-2) s(-1) angstrom(-1), which corresponds to 1.87 x 10(-20) erg cm(-2) s(-1) arcsec(-2) or 0.0033 Rayleigh. This detection is 34 times fainter than a previous strict limit obtained using deep narrow-band imaging. The faintness of the signal demonstrates why it has been so difficult to trace recombination radiation out to large radii around galaxies. This signal, combined with published estimates of n(H), leads us to estimate the temperature of the gas to be 12,000 K, consistent with independent empirical estimates based on metal ion absorption lines and expectations from numerical simulations.

Aims. The goal of this paper is to present complete radial-velocity data for the spectroscopically selected McCormick sample of nearby K-M dwarfs and, based on these and supplementary data, to determine the space-velocity distributions of late-type stars in the solar neighborhood. Methods. We analyzed nearly 3300 measurements of radial velocities for 1049 K-M dwarfs, that we obtained during the past decade with a CORAVEL-type instrument, with a primary emphasis on detecting and eliminating from kinematic calculations the spectroscopic binaries and binary candidates. Combining radial-velocity data with HIPPARCOS/Tycho-2 astrometry we calculated the space-velocity components and parameters of the galactic orbits in a three-component model potential for the stars in the sample, that we use for kinematical analysis and for the identification of possible candidate members of nearby stellar kinematic groups. Results. We present the catalog of our observations of radial velocities for 959 stars which are not suspected of velocity variability, along with the catalog of U, V, W velocities and Galactic orbital parameters for a total of 1088 K-M stars which are used in the present kinematic analysis. Of these, 146 stars were identified as possible candidate members of the known nearby kinematic groups and suspected subgroups. The distributions of space-velocity components, orbital eccentricities, and maximum distances from the Galactic plane are consistent with the presence of young, intermediate-age and old populations of the thin disk and a small fraction (similar to 3%) of stars with the thick disk kinematics. The kinematic structure gives evidence that the bulk of K-M type stars in the immediate solar vicinity represents a dynamically relaxed stellar population. The star MCC 869 is found to be on a retrograde Galactic orbit (V = -262 km s(-1)) of low inclination (4 degrees) and can be a member of stellar stream of some dissolved structure. The Sun's velocity with respect to the Local Standard of Rest, derived from the distributions of space-velocity components, is (U-circle dot, V-circle dot, W-circle dot) = (9.0 +/- 1.4, 13.1 +/- 0.6, 7.2 +/- 0.8) km s(-1). The radial solar motion derived via the Stromberg's relation, V-circle dot = 14.2 +/- 0.8 km s(-1), agrees within the errors with the value obtained directly from the V distribution of stars on nearly circular orbits.

Fornecemos uma amostra de 170 Aglomerados Globulares Galácticos (GCs) e analisamos as propriedades de sua distribuição espacial. Utilizando um vasto catálogo de nuvens escuras identificadas, listamos os GCs que estão atrás de uma ou mais delas e que podem estar submetidos a uma extinção mais complexa do que a considerada por mapas de extinção. Valores de incerteza em distância são obtidos da literatura recente e comparados com valores derivados de uma fórmula de propagação de erro. GCs são agrupados de acordo com características inusitadas, tais como idades relativamente jovens ou possível conexão com núcleos de galáxias anãs, de forma que o efeito desses grupos pode ser isolado na distribuição espacial geral. Adicionalmente, computamos o centróide da distribuição de GCs e estudamos como esse se relaciona com a distância ao centro da Galáxia. Considerando que uma formação galáctica via colapso monolítico é supostamente simétrica, investigamos assimetrias e como os valores de incerteza das distâncias as modificam. Velocidades espaciais e um potencial Galáctico são empregados para verificar se quaisquer assimetrias na distribuição espacial são devidas a objetos em movimento coerente, ou se são somente efeitos transientes. / We provide a sample of 170 Galactic Globular Clusters (GCs) and analyse its spatial distribution properties. Using a comprehensive dust cloud catalogue, we list the GCs that are behind one or more identified dust clouds and could be subjected to a more complex extinction curve than extinction catalogues consider. Distance uncertainty values are gathered from recent literature and compared to values derived from an error propagation formula. GCs are grouped according to unusual characteristics, such as relatively young age or possible connection to dwarf galaxy nuclei, so that their effect on the general distribution can be isolated. Additionally, we compute the centroid of the GC distribution and study how it relates to the distance to the centre of the Galaxy. Considering that galactic formation via monolithic collapse is expected to be symmetrical, we probe asymmetries and how distance uncertainty values modify them. Spatial velocities and a Galactic potential are used to verify if any asymmetries in the spatial distribution are due to co-moving objects, or if they are merely transient effects.

Optical spectroscopy and modeling are applied to four independent problems related to the structure and evolution of galaxies. The problems cover a broad range of look-back time and galaxy mass. Integral field spectroscopy with low surface brightness sensitivity is the tool employed to advance our understanding of the distribution, interplay, and evolution of the stars, dark matter, and gas. First, I review development and commissioning work done on the VIRUS-P instrument. I then present a large sample of galaxies over redshifts 1.9<z<3.8 selected solely through their Lyman-alpha flux. This work is done as a pilot survey to the Hobby-Eberly Telescope Dark Energy eXperiment (HETDEX). I create a redshift catalog of 397 galaxies discovered over 169 square arcsecs taken over 113 nights. Second, I study a high redshift (z=3.4) radio galaxy halo by mapping the Lyman-alpha velocity field. The signal extends far beyond the optical and radio extents of the system. Plausible, but non-unique, models are made to explain the Lyman-alpha signal that require a very large reservoir of neutral hydrogen (>= 10E12 solar masses). Third, I study the dark matter halo profile in a nearby late-type dwarf galaxy in the context of the "core-cusp" controversy. N-body simulations predict such galaxies to have cuspy dark matter halos, while HI rotation curves and more recent hydrodynamical simulations indicate that such halos may instead be strongly cored. I measure the spatially resolved stellar velocity field and fit with two-integral Jeans models. A cuspy halo is preferred from the stellar kinematics. The mass models from stellar and gaseous kinematics disagree. The gas models assume circular motion in an infinitely thin disk which is likely unrealistic. The stellar kinematics presented are the first measurements of a collision-less tracer in such galaxies. Fourth, I attempt to measure diffuse H-alpha emission, fluoresced by the metagalactic UV background, in the outskirts of a nearby gas rich galaxy. I do not make a detection, but the deep flux limit over a large field-of-view places the most sensitive limit to-date on the UV background's photoionization rate of Gamma(z=0)<1.7x10E-14 1/s at 5 sigma certainty. / text

Fornecemos uma amostra de 170 Aglomerados Globulares Galácticos (GCs) e analisamos as propriedades de sua distribuição espacial. Utilizando um vasto catálogo de nuvens escuras identificadas, listamos os GCs que estão atrás de uma ou mais delas e que podem estar submetidos a uma extinção mais complexa do que a considerada por mapas de extinção. Valores de incerteza em distância são obtidos da literatura recente e comparados com valores derivados de uma fórmula de propagação de erro. GCs são agrupados de acordo com características inusitadas, tais como idades relativamente jovens ou possível conexão com núcleos de galáxias anãs, de forma que o efeito desses grupos pode ser isolado na distribuição espacial geral. Adicionalmente, computamos o centróide da distribuição de GCs e estudamos como esse se relaciona com a distância ao centro da Galáxia. Considerando que uma formação galáctica via colapso monolítico é supostamente simétrica, investigamos assimetrias e como os valores de incerteza das distâncias as modificam. Velocidades espaciais e um potencial Galáctico são empregados para verificar se quaisquer assimetrias na distribuição espacial são devidas a objetos em movimento coerente, ou se são somente efeitos transientes. / We provide a sample of 170 Galactic Globular Clusters (GCs) and analyse its spatial distribution properties. Using a comprehensive dust cloud catalogue, we list the GCs that are behind one or more identified dust clouds and could be subjected to a more complex extinction curve than extinction catalogues consider. Distance uncertainty values are gathered from recent literature and compared to values derived from an error propagation formula. GCs are grouped according to unusual characteristics, such as relatively young age or possible connection to dwarf galaxy nuclei, so that their effect on the general distribution can be isolated. Additionally, we compute the centroid of the GC distribution and study how it relates to the distance to the centre of the Galaxy. Considering that galactic formation via monolithic collapse is expected to be symmetrical, we probe asymmetries and how distance uncertainty values modify them. Spatial velocities and a Galactic potential are used to verify if any asymmetries in the spatial distribution are due to co-moving objects, or if they are merely transient effects.

Fornecemos uma amostra de 170 Aglomerados Globulares Galácticos (GCs) e analisamos as propriedades de sua distribuição espacial. Utilizando um vasto catálogo de nuvens escuras identificadas, listamos os GCs que estão atrás de uma ou mais delas e que podem estar submetidos a uma extinção mais complexa do que a considerada por mapas de extinção. Valores de incerteza em distância são obtidos da literatura recente e comparados com valores derivados de uma fórmula de propagação de erro. GCs são agrupados de acordo com características inusitadas, tais como idades relativamente jovens ou possível conexão com núcleos de galáxias anãs, de forma que o efeito desses grupos pode ser isolado na distribuição espacial geral. Adicionalmente, computamos o centróide da distribuição de GCs e estudamos como esse se relaciona com a distância ao centro da Galáxia. Considerando que uma formação galáctica via colapso monolítico é supostamente simétrica, investigamos assimetrias e como os valores de incerteza das distâncias as modificam. Velocidades espaciais e um potencial Galáctico são empregados para verificar se quaisquer assimetrias na distribuição espacial são devidas a objetos em movimento coerente, ou se são somente efeitos transientes. / We provide a sample of 170 Galactic Globular Clusters (GCs) and analyse its spatial distribution properties. Using a comprehensive dust cloud catalogue, we list the GCs that are behind one or more identified dust clouds and could be subjected to a more complex extinction curve than extinction catalogues consider. Distance uncertainty values are gathered from recent literature and compared to values derived from an error propagation formula. GCs are grouped according to unusual characteristics, such as relatively young age or possible connection to dwarf galaxy nuclei, so that their effect on the general distribution can be isolated. Additionally, we compute the centroid of the GC distribution and study how it relates to the distance to the centre of the Galaxy. Considering that galactic formation via monolithic collapse is expected to be symmetrical, we probe asymmetries and how distance uncertainty values modify them. Spatial velocities and a Galactic potential are used to verify if any asymmetries in the spatial distribution are due to co-moving objects, or if they are merely transient effects.

In this paper, we report a new estimate of the absolute proper motion (PM) of the globular cluster NGC 5139 (omega Cen) as part of the HST large program GO-14118+ 14662. We analyzed a field 17 arcmin southwest of the center of omega Cen and computed PMs with epoch spans of similar to 15.1 years. We employed 45 background galaxies to link our relative PMs to an absolute reference-frame system. The absolute PM of the cluster in our field is (mu(alpha) cos delta, mu(delta))=(-3.341. 0.028, -6.557 +/- 0.043) mas yr(-1). Upon correction for the effects of viewing perspective and the known cluster rotation, this implies that for the cluster center of mass (mu(alpha) cos delta, mu(delta))=(-3.238. 0.028, -6.716 +/- 0.043) mas yr(-1). This measurement is direct and independent, has the highest random and systematic accuracy to date, and will provide an external verification for the upcoming Gaia Data Release 2. It also differs from most reported PMs for omega Cen in the literature by more than 5 sigma, but consistency checks compared to other recent catalogs yield excellent agreement. We computed the corresponding Galactocentric velocity, calculated the implied orbit of omega Cen in two different Galactic potentials, and compared these orbits to the orbits implied by one of the PM measurements available in the literature. We find a larger (by about 500 pc) perigalactic distance for omega Cen with our new PM measurement, suggesting a larger survival expectancy for the cluster in the Galaxy.