187 research outputs found

    The AMIGA sample of isolated galaxies - II. Morphological refinement

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    We present a complete POSS II-based refinement of the optical morphologies for galaxies in the Karatchenseva's Catalog of Isolated Galaxies that forms the basis of the AMIGA project. Comparison with independent classifications made for an SDSS overlap sample of more than 200 galaxies confirms the reliability of the early vs. late-type discrimination and the accuracy of spiral subtypes within DeltaT = 1-2. CCD images taken at the OSN were also used to solve ambiguities. 193 galaxies are flagged for the presence of nearby companions or signs of distortion likely due to interaction. This most isolated sample of galaxies in the local Universe is dominated by 2 populations: 1) 82% spirals (Sa-Sd) with the bulk being luminous systems with small bulges (63% between types Sb-Sc) and 2) a significant population of early-type E-S0 galaxies (14%). Most of the types later than Sd are low luminosity galaxies concentrated in the local supercluster where isolation is difficult to evaluate. The late-type spiral majority of the sample spans a luminosity range M_B-corr = -18 to -22 mag. Few of the E/S0 population are more luminous than -21.0 marking an absence of, an often sought, super L* merger (eg fossil elliptical) population. The rarity of high luminosity systems results in a fainter derived M* for this population compared to the spiral optical luminosity function (OLF). The E-S0 population is from 0.2 to 0.6 mag fainter depending how the sample is defined. This marks the AMIGA sample as almost unique among samples that compare early and late-type OLFs separately. In other samples, which always involve galaxies in higher density environments, M*(E/S0) is almost always 0.3-0.5 mag brighter than M*(S), presumably reflecting a stronger correlation between M* and environmental density for early-type galaxies.Comment: A&A accepted, 13 pages, 9 figures, 8 tables. Higher resolution Fig. 1 and full tables are available on the AMIGA (Analysis of the interstellar Medium of Isolated GAlaxies) website at http://www.iaa.es/AMIGA.htm

    Manejo florestal comunitário e familiar: percepções de pequenos produtores rurais na BR-163 e BR-230, Pará.

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    O Manejo Florestal Comunitário e Familiar (MFCF) tomou-se promissora alternativa de renda para povos tradicionais e comunidades rurais. Dentre os beneficiários das políticas do MFCF (i.e. Decreto n° 6.874/09) estão colonos de assentamentos rurais. Estes, embora motivados pelo dinheiro e pela melhoria das infraestruturas locais, não recebem assistência técnica e outros tipos de apoio institucionais necessários que conduzem ao sucesso da atividade. Nesse contexto, este trabalho analisou as características de alguns contratos formais celebrados entre assentados e o setor madeireiro na BR-163 e BR-230, estado do Pará, dando enfoque nas percepções dos produtores rurais quanto às relações entre atores locais e regionais que atuam nos assentamentos e que estão envolvidos de alguma forma no manejo florestal madeireiro na região do estudo. Observou-se que as melhores relações são aquelas em que os atores mantém presença física nos assentamentos e que, órgãos importantes, como o SFB, não têm visibilidade de suas ações nessas localidades, mostrando gargalos na implementação de programas governamentais de apoio ao MFCF. Observou-se também que as lideranças possuem uma percepção mais complexa das relações entre os atores. Para melhorias, sugere-se maior abertura no diálogo entre governo e produtores rurais e apoio técnico através de assistência técnica e extensão florestal

    Manejo madeireiro comunitário em áreas protegidas da Amazônia: aprendizados e recomendações de como facilitar a troca de experiências entre comunidades e organizações.

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    Este documento apresenta um histórico do manejo madeireiro comunitário na Amazônia brasileira e a motivação para promover a troca de experiências; descreve o percurso metodológico adotado para a realização do encontro; e analisa os aprendizados do processo de organização do evento e dos casos de manejo madeireiro comunitário. Espera-se que possa contribuir com as iniciativas de uso sustentável das florestas por comunidades locais da Amazônia.bitstream/item/222907/1/27125.pd

    First Results from High Angular Resolution ALMA Observations Toward the HL Tau Region

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    We present Atacama Large Millimeter/submillimeter Array (ALMA) observations from the 2014 Long Baseline Campaign in dust continuum and spectral line emission from the HL Tau region. The continuum images at wavelengths of 2.9, 1.3, and 0.87 mm have unprecedented angular resolutions of 0.075 arcseconds (10 AU) to 0.025 arcseconds (3.5 AU), revealing an astonishing level of detail in the circumstellar disk surrounding the young solar analogue HL Tau, with a pattern of bright and dark rings observed at all wavelengths. By fitting ellipses to the most distinct rings, we measure precise values for the disk inclination (46.72pm0.05 degrees) and position angle (+138.02pm0.07 degrees). We obtain a high-fidelity image of the 1.0 mm spectral index (α\alpha), which ranges from α2.0\alpha\sim2.0 in the optically-thick central peak and two brightest rings, increasing to 2.3-3.0 in the dark rings. The dark rings are not devoid of emission, we estimate a grain emissivity index of 0.8 for the innermost dark ring and lower for subsequent dark rings, consistent with some degree of grain growth and evolution. Additional clues that the rings arise from planet formation include an increase in their central offsets with radius and the presence of numerous orbital resonances. At a resolution of 35 AU, we resolve the molecular component of the disk in HCO+ (1-0) which exhibits a pattern over LSR velocities from 2-12 km/s consistent with Keplerian motion around a ~1.3 solar mass star, although complicated by absorption at low blue-shifted velocities. We also serendipitously detect and resolve the nearby protostars XZ Tau (A/B) and LkHa358 at 2.9 mm.Comment: 11 pages, 5 figures, 2 tables, accepted for publication in the Astrophysical Journal Letter

    ALMA Observations of Asteroid 3 Juno at 60 Kilometer Resolution

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    We present Atacama Large Millimeter/submillimeter Array (ALMA) 1.3 mm continuum images of the asteroid 3 Juno obtained with an angular resolution of 0.042 arcseconds (60 km at 1.97 AU). The data were obtained over a single 4.4 hr interval, which covers 60% of the 7.2 hr rotation period, approximately centered on local transit. A sequence of ten consecutive images reveals continuous changes in the asteroid's profile and apparent shape, in good agreement with the sky projection of the three-dimensional model of the Database of Asteroid Models from Inversion Techniques. We measure a geometric mean diameter of 259pm4 km, in good agreement with past estimates from a variety of techniques and wavelengths. Due to the viewing angle and inclination of the rotational pole, the southern hemisphere dominates all of the images. The median peak brightness temperature is 215pm13 K, while the median over the whole surface is 197pm15 K. With the unprecedented resolution of ALMA, we find that the brightness temperature varies across the surface with higher values correlated to the subsolar point and afternoon areas, and lower values beyond the evening terminator. The dominance of the subsolar point is accentuated in the final four images, suggesting a reduction in the thermal inertia of the regolith at the corresponding longitudes, which are possibly correlated to the location of the putative large impact crater. These results demonstrate ALMA's potential to resolve thermal emission from the surface of main belt asteroids, and to measure accurately their position, geometric shape, rotational period, and soil characteristics.Comment: 8 pages, 3 figures, 2 tables, accepted for publication in the Astrophysical Journal Letter

    ALMA Long Baseline Observations of the Strongly Lensed Submillimeter Galaxy HATLAS J090311.6+003906 at z=3.042

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    We present initial results of very high resolution Atacama Large Millimeter/submillimeter Array (ALMA) observations of the zz=3.042 gravitationally lensed galaxy HATLAS J090311.6+003906 (SDP.81). These observations were carried out using a very extended configuration as part of Science Verification for the 2014 ALMA Long Baseline Campaign, with baselines of up to 15 km. We present continuum imaging at 151, 236 and 290 GHz, at unprecedented angular resolutions as fine as 23 milliarcseconds (mas), corresponding to an un-magnified spatial scale of ~180 pc at z=3.042. The ALMA images clearly show two main gravitational arc components of an Einstein ring, with emission tracing a radius of ~1.5". We also present imaging of CO(10-9), CO(8-7), CO(5-4) and H2O line emission. The CO emission, at an angular resolution of ~170 mas, is found to broadly trace the gravitational arc structures but with differing morphologies between the CO transitions and compared to the dust continuum. Our detection of H2O line emission, using only the shortest baselines, provides the most resolved detection to date of thermal H2O emission in an extragalactic source. The ALMA continuum and spectral line fluxes are consistent with previous Plateau de Bure Interferometer and Submillimeter Array observations despite the impressive increase in angular resolution. Finally, we detect weak unresolved continuum emission from a position that is spatially coincident with the center of the lens, with a spectral index that is consistent with emission from the core of the foreground lensing galaxy.Comment: 9 pages, 5 figures and 3 tables, accepted for publication in the Astrophysical Journal Letter

    [CII] line emission in massive star-forming galaxies at z=4.7

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    We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of the [CII] 157.7micron fine structure line and thermal dust continuum emission from a pair of gas-rich galaxies at z=4.7, BR1202-0725. This system consists of a luminous quasar host galaxy and a bright submm galaxy (SMG), while a fainter star-forming galaxy is also spatially coincident within a 4" (25 kpc) region. All three galaxies are detected in the submm continuum, indicating FIR luminosities in excess of 10^13 Lsun for the two most luminous objects. The SMG and the quasar host galaxy are both detected in [CII] line emission with luminosities, L([CII]) = (10.0 +/- 1.5)x10^9 Lsun and L([CII]) = (6.5+/-1.0)x10^9 Lsun, respectively. We estimate a luminosity ratio, L([CII])/L(FIR) = (8.3+/-1.2)x10^-4 for the starburst SMG to the North, and L([CII])/L(FIR) = (2.5+/-0.4)x10^-4 for the quasar host galaxy, in agreement with previous high-redshift studies that suggest lower [CII]-to-FIR luminosity ratios in quasars than in starburst galaxies. The third fainter object with a flux density, S(340GHz) = 1.9+/-0.3 mJy, is coincident with a Ly-Alpha emitter and is detected in HST ACS F775W and F814W images but has no clear counterpart in the H-band. Even if this third companion does not lie at a similar redshift to BR1202-0725, the quasar and the SMG represent an overdensity of massive, infrared luminous star-forming galaxies within 1.3 Gyr of the Big Bang.Comment: 14 pages, accepted for publication in ApJ Letter

    An Overview of the 2014 ALMA Long Baseline Campaign

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    A major goal of the Atacama Large Millimeter/submillimeter Array (ALMA) is to make accurate images with resolutions of tens of milliarcseconds, which at submillimeter (submm) wavelengths requires baselines up to ~15 km. To develop and test this capability, a Long Baseline Campaign (LBC) was carried out from September to late November 2014, culminating in end-to-end observations, calibrations, and imaging of selected Science Verification (SV) targets. This paper presents an overview of the campaign and its main results, including an investigation of the short-term coherence properties and systematic phase errors over the long baselines at the ALMA site, a summary of the SV targets and observations, and recommendations for science observing strategies at long baselines. Deep ALMA images of the quasar 3C138 at 97 and 241 GHz are also compared to VLA 43 GHz results, demonstrating an agreement at a level of a few percent. As a result of the extensive program of LBC testing, the highly successful SV imaging at long baselines achieved angular resolutions as fine as 19 mas at ~350 GHz. Observing with ALMA on baselines of up to 15 km is now possible, and opens up new parameter space for submm astronomy.Comment: 11 pages, 7 figures, 2 tables; accepted for publication in the Astrophysical Journal Letters; this version with small changes to affiliation

    The Gas and Stellar Content of a Metal-poor Galaxy at z = 8.496 as Revealed by JWST and ALMA

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    We present a joint analysis of the galaxy S04590 at z = 8.496 based on NIRSpec, NIRCam, and NIRISS observations obtained as part of the Early Release Observations program of the James Webb Space Telescope (JWST) and the far-infrared [C ii] 158 μm emission line detected by dedicated Atacama Large Millimeter/submillimeter Array (ALMA) observations. We determine the physical properties of S04590 from modeling of the spectral energy distribution (SED) and through the redshifted optical nebular emission lines detected with JWST/NIRSpec. The best-fit SED model reveals a low-mass (M ⋆ = 107.2-108 M ⊙) galaxy with a low oxygen abundance of 12 + log ( O / H ) = 7.16 − 0.12 + 0.10 derived from the strong nebular and auroral emission lines. Assuming that [C ii] effectively traces the interstellar medium, we estimate the total gas mass of the galaxy to be M gas = (8.0 \ub1 4.0) 7 108 M ⊙ based on the luminosity and spatial extent of [C ii]. This yields an exceptionally high gas fraction, f gas = M gas/(M gas + M ⋆) ≳ 90%, though one still consistent with the range expected for low metallicity. We further derive the metal mass of the galaxy based on the gas mass and gas-phase metallicity, which we find to be consistent with the expected metal production from Type II supernovae. Finally, we make the first constraints on the dust-to-gas (DTG) and dust-to-metal (DTM) ratios of galaxies in the epoch of reionization at z ≳ 6, showing overall low mass ratios of logDTG < −3.8 and logDTM < −0.5, though they are consistent with established scaling relations and in particular with those of the local metal-poor galaxy I Zwicky 18. Our analysis highlights the synergy between ALMA and JWST in characterizing the gas, metal, and stellar content of the first generation of galaxies
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