883 research outputs found

    Urbanismo aruccitano: el trazado regulador de la domus norte

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    En el siguiente trabajo se presenta una propuesta del trazado regulador de la denominada Casa Norte de la ciudad de Arucci, uno de los elementos urbanos mejor conocidos en su planta arquitectónica. El estudio de su modulación y el trazado regulador que rigió su diseño definen diversas particularidades de este conjunto estructural como son la ruptura de su eje mayor, el acceso en uno de los lados mayores, así como otros elementos que la caracterizan. Con todo, se muestran diversos resultados que definen de una manera cada vez más nítida el trazado viario de la ciudad de un modo general y la arquitectura doméstica de la ciudad en particular

    An extremely high velocity molecular jet surrounded by an ionized cavity in the protostellar source Serpens SMM1

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    We report ALMA observations of a one-sided, high-velocity (\sim80 km s1^{-1}) CO(J=21J = 2 \rightarrow 1) jet powered by the intermediate-mass protostellar source Serpens SMM1-a. The highly collimated molecular jet is flanked at the base by a wide-angle cavity; the walls of the cavity can be seen in both 4 cm free-free emission detected by the VLA and 1.3 mm thermal dust emission detected by ALMA. This is the first time that ionization of an outflow cavity has been directly detected via free-free emission in a very young, embedded Class 0 protostellar source that is still powering a molecular jet. The cavity walls are ionized either by UV photons escaping from the accreting protostellar source, or by the precessing molecular jet impacting the walls. These observations suggest that ionized outflow cavities may be common in Class 0 protostellar sources, shedding further light on the radiation, outflow, and jet environments in the youngest, most embedded forming stars.Comment: 6 pages, 4 figures, accepted for publication in the Astrophysical Journal Letter

    A Multiple System of Radio Sources at the Core of the L723 Multipolar Outflow

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    We present high angular resolution Very Large Array multi-epoch continuum observations at 3.6 cm and 7 mm towards the core of the L723 multipolar outflow revealing a multiple system of four radio sources suspected to be YSOs in a region of only ~4 arcsecs (1200 AU) in extent. The 3.6 cm observations show that the previously detected source VLA 2 contains a close (separation ~0.29 arcsecs or ~90 AU) radio binary, with components (A and B) along a position angle of ~150 degrees. The northern component (VLA 2A) of this binary system is also detected in the 7 mm observations, with a positive spectral index between 3.6 cm and 7 mm. In addition, the source VLA 2A is associated with extended emission along a position angle of ~115 degrees, that we interpret as outflowing shock-ionized gas that is exciting a system of HH objects with the same position angle. A third, weak 3.6 cm source, VLA 2C, that is detected also at 7 mm, is located ~0.7 arcsecs northeast of VLA 2A, and is possibly associated with the water maser emission in the region. The 7 mm observations reveal the presence of an additional source, VLA 2D, located ~3.5 arcsecs southeast of VLA 2A, and with a 1.35 mm counterpart. All these radio continuum sources have a positive spectral index, compatible with them being YSOs. We also propose that the high velocity CO emission observed in the region could be the superposition of multiple outflows (at least three independent bipolar outflows) excited by the YSOs located at the core, instead of the previous interpretations in terms of only one or two outflows.Comment: Accepted for publication in The Astrophysical Journal (2007 December 6

    Weak and Compact Radio Emission in Early High-Mass Star Forming Regions: I. VLA Observations

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    We present a high sensitivity radio continuum survey at 6 and 1.3\,cm using the Karl G. Jansky Very Large Array towards a sample of 58 high-mass star forming regions. Our sample was chosen from dust clumps within infrared dark clouds with and without IR sources (CMC-IRs, CMCs, respectively), and hot molecular cores (HMCs), with no previous, or relatively weak radio continuum detection at the 11\,mJy level. Due to the improvement in the continuum sensitivity of the VLA, this survey achieved map rms levels of \sim 3-10 μ\muJy beam1^{-1} at sub-arcsecond angular resolution. We extracted 70 centimeter continuum sources associated with 1.2\,mm dust clumps. Most sources are weak, compact, and are prime candidates for high-mass protostars. Detection rates of radio sources associated with the mm dust clumps for CMCs, CMC-IRs and HMCs are 6%\%, 53%\% and 100%\%, respectively. This result is consistent with increasing high-mass star formation activity from CMCs to HMCs. The radio sources located within HMCs and CMC-IRs occur close to the dust clump centers with a median offset from it of 12,000\,AU and 4,000\,AU, respectively. We calculated 5 - 25\,GHz spectral indices using power law fits and obtain a median value of 0.5 (i.e., flux increasing with frequency), suggestive of thermal emission from ionized jets. In this paper we describe the sample, observations, and detections. The analysis and discussion will be presented in Paper II.Comment: Accepted for publication in the ApJ
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