Bibliografías temáticas / IR and radio emission lines

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Literatura académica sobre el tema "IR and radio emission lines"

Autor: Grafiati

Publicado: 4 de junio de 2021

Última modificación: 10 de febrero de 2022

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Artículos de revistas sobre el tema "IR and radio emission lines"

Cohen, R. J. "Circumstellar envelopes of OH-IR sources". Symposium - International Astronomical Union 122 (1987): 229–39. http://dx.doi.org/10.1017/s0074180900156499.

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This article reviews recent radio observations of maser emission from OH, H2O and SiO molecules in the circumstellar envelopes of OH-IR sources. The different radio lines require different conditions for their excitation, and each therefore probes different regions in the circumstellar envelope. For some stars radio interferometer maps of several maser lines are now available, and a consistent picture of the envelope structure is beginning to emerge.

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Riffel, Rogemar A., Thaisa Storchi-Bergmann y Rogério Riffel. "Near-IR Integral Field Spectroscopy of the central region of NGC 5929". Proceedings of the International Astronomical Union 10, S309 (julio de 2014): 339. http://dx.doi.org/10.1017/s1743921314010321.

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AbstractWe present two-dimensional (2D) near-infrared spectra of the inner 300×300 pc2 of the Seyfert 2 galaxy NGC 5929 at a spatial resolution of ~20 pc obtained with the Gemini Near infrared Integral Field Spectrograph (NIFS). We present 2D maps for the emission line flux distributions and kinematics and report the discovery of a linear structure ~300 pc in extent and of ~50 pc in width oriented perpendicular to the radio jet, showing broadened emission-line profiles.While over most of the field the emission-line profiles have full-widths-at-half-maximum (FWHM) of ~210 km/s, at a linear structure perpendicular do the radio jet the emission-line FWHMs are twice this value, and are due to two velocity components, one blueshifted and the other redshifted relative to the systemic velocity. We attribute these velocities to an outflow from the nucleus which is launched perpendicular to the radio jet. We reported the detection of this peculiar outflow in Riffel, Storchi-Bergmann & Riffel (2014a), where more details of the analysis can be found. Since, NGC 5929 has a Type 2 nucleus, this detection implies that: (1) both ionizing radiation and relativistic particles are escaping through holes in the torus perpendicular to the radio jet; and/or (2) the torus is also outflowing, as proposed by recent models of tori as winds from the outer parts of an accretion flow; or (3) the torus is absent in NGC 5929.At other locations the gas kinematics is dominated by rotation in a disk, although some evidences of interaction of the radio jet with the emitting gas are seen as a broadening of the line profiles at the locations of the radio structures.The flux distributions for the [P ii], [Fe ii], H i and H2 emission lines show that the line emission is more extended along the PA = 60/240^, extending to up to 1.5” to both sides of the nucleus, while to the perpendicular direction (PA = -30/150^) the emission is extended to 0.7” from the nucleus. The flux distributions of all emission lines show a good correlation with radio the radio structures, with the two peak of emission associated to the soutwestern and northeastern radio knots. Some differences are observed among distinct emission lines. While the [Fe ii] and H2 emission peak at the location of the soutwestern radio structure at 0.6” from the nucleus, the H i recombination lines present the their highest fluxes at the location of the northeastern radio hotspot at 0.5” from the nucleus. Another difference is that the H2 emission is less collimated than that for other lines, being more extended perpendicularly to the radio jet. A detailed analysis of the line emission and kinematics will be presented in Riffel, Storchi-Bergmann & Riffel (2014b).

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Ferris, E. R., A. W. Blain, R. J. Assef, N. A. Hatch, A. Kimball, M. Kim, A. Sajina et al. "The black hole masses of extremely luminous radio-WISE selected galaxies". Monthly Notices of the Royal Astronomical Society 502, n.º 1 (11 de enero de 2021): 1527–48. http://dx.doi.org/10.1093/mnras/stab048.

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ABSTRACT We present near-IR photometry and spectroscopy of 30 extremely luminous radio and mid-IR-selected galaxies. With bolometric luminosities exceeding ∼1013 $\rm {L_{\odot }}$ and redshifts ranging from z = 0.880 to 2.853, we use Very Large Telescope instruments X-shooter and Infrared Spectrometer and Array Camera to investigate this unique population of galaxies. Broad multicomponent emission lines are detected in 18 galaxies and we measure the near-IR lines $\rm {H\,\rm {\beta }}$, $\rm{[O\,{\small III}]}\, \rm {\lambda }\rm {\lambda }4959,5007$, and $\rm {H\,\rm {\alpha }}$ in 6, 15, and 13 galaxies, respectively, with 10 $\rm {Ly\,\alpha }$ and 5 C iv lines additionally detected in the UVB arm. We use the broad $\rm{[O\,{\small III}]}\, \rm {\lambda }5007$ emission lines as a proxy for the bolometric active galactic nucleus luminosity, and derive lower limits to supermassive black hole masses of 107.9–109.4 M⊙ with expectations of corresponding host masses of 1010.4–1012.0 M⊙. We measure $\rm {\lambda }_{Edd}$ > 1 for eight of these sources at a 2σ significance. Near-IR photometry and SED fitting are used to compare stellar masses directly. We detect both Balmer lines in five galaxies and use these to infer a mean visual extinction of AV = 2.68 mag. Due to non-detections and uncertainties in our ${\rm H}\, \beta$ emission line measurements, we simulate a broad ${\rm H}\, \beta$ line of FWHM = 1480 $\rm {kms^{-1}}$ to estimate extinction for all sources with measured ${\rm H}\, \alpha$ emission. We then use this to infer a mean AV = 3.62 mag, demonstrating the highly obscured nature of these galaxies, with the consequence of increasing our estimates of black hole masses by a 0.5 orders of magnitude in the most extreme and obscured cases.

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di Serego Alighieri, Sperello y Andrea Cimatti. "Misdirected Quasars in Distant Radio Galaxies". Symposium - International Astronomical Union 159 (1994): 21–24. http://dx.doi.org/10.1017/s0074180900174789.

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We present the results of recent spectro–polarimetry and imaging–polarimetry of distant radio galaxies which show: (1) broad polarized permitted emission lines, (2) narrow unpolarized forbidden emission lines, (3) a flat (in fλ) polarized UV continuum and (4) an absorption feature, probably interstellar. The direction of the E vector of polarization is always perpendicular to the optical/radio axis. These observations are strong evidence that these objects harbour a quasar, which is visible only through scattering by the interstellar medium of the galaxy. The continuum polarization drops to the red of the 4000Å break, suggesting dilution by an evolved stellar population. A two-component model made of a dust scattered quasar and an evolved stellar population reproduces well the polarization and the spectral energy distribution, including the IR data.

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Down, Emily. "Modeling the Orientation of AGN". Proceedings of the International Astronomical Union 5, S267 (agosto de 2009): 107. http://dx.doi.org/10.1017/s1743921310005685.

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The orientation of nineteen 0.8< z < 2.3 radio-loud quasars was measured using two independent methods. First, Hα was observed in the near IR using ISAAC at the VLT. The complex Hα emission lines were fitted with a range of models, some including emission from a flattened, extended accretion disk following Chen & Halpern (1989). The models were compared using the Bayesian evidence, and the disk axis angles recovered. Second, models were fitted to the ~10 MHz to 20 GHz radio spectral energy distributions (SEDs) to recover the jet angles, assuming that the emission is comprised of a broken power law arising from the radio lobes plus a Doppler-boosted core.

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Maxfield, L., S. G. Djorgovski, D. Thompson, M. A. Pahre, R. R. de Carvalho, M. Vigotti y G. Grueff. "Optical and IR Properties of Radio Galaxies as a Function of their Radio Power". Symposium - International Astronomical Union 171 (1996): 414. http://dx.doi.org/10.1017/s0074180900233330.

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We compare optical and infrared photometric and spectroscopic properties of high-redshift radio galaxies from the 3CR and B3 surveys. At a given redshift and a fixed restframe frequency, the two samples differ on average by an order of magnitude in radio power, thus providing a fair baseline in radio powerfor a range of redshifts. We present new optical and IR photometry and spectrosopy for a number of B3 sources. We combine these data with the existing corresponding information on B3 and 3CR sources, in order to explore different correlations of source properties with redshift, and among themselves. B3 sources follow the same trend as 3CR's in the K band Hubble diagram, although they do seem to be slightly fainter on average at a given redshift. This trend is slightly more prominent in the Gunn r band. This suggests that some fraction of the observed light in the r and K bands is contributed by an active nucleus, which also powers the radio lobes. The B3's also tend to have lower emission line luminosities than 3CR's at any given redshift, suggesting that there may be a correlation between line luminosity and radio power. Such a correlation is clearly seen and is followed by both samples. It suggests that the UV emission lines are largely powered by the active nucleus, ostensibly a hidden quasar, which is also responsible for the radio emission. We also examine the behavior of the optical and radio PA alignments for the combined B3+3CR data set. We find that high-power and high-redshift subsamples for both B3's and 3CR's show the alignments more prominently, but we still cannot tell which of these variables dominates this effect. This work was supported in part by the NSF PYI award AST-9157412, and the Bressler Foundation.

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Perlman, Eric S., Chris L. Carilli, John T. Stocke y John Conway. "PKS 1413+135: A Very Young Radio Galaxy". Symposium - International Astronomical Union 175 (1996): 90–91. http://dx.doi.org/10.1017/s0074180900080141.

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PKS 1413+135 is an enigma: while classified as a BL Lac due to its polarized near-IR continuum (Stocke et al. 1992) and optical spectrum (Beichmann et al. 1981), it appears to lie within a spiral host (McHardy et al. 1991, Stocke et al. 1992). In addition, the AGN is highly obscured (Beichmann et al. 1981, Carilli et al. 1992, Stocke et al. 1992, Wiklind & Combes 1994, 1995). Yet there is no evidence that the absorbing gas is being heated and re-emitting the AGN radiation in the form of thermal IR or emission lines (as in, e.g., Sey 2s). This led Stocke et al. (1992) to suggest that the AGN might be background to the optical galaxy.

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Akujor, Chidi E., R. W. Porcas, A. R. Patnaik y A. Ardeberg. "Optically Quiet Quasars – Radio and Optical Investigations". Symposium - International Astronomical Union 159 (1994): 419. http://dx.doi.org/10.1017/s0074180900176041.

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The activity in the nuclei of bright galaxies could arise from a number of sources: they may contain compact variable radio sources, they may be strong IR/optical/X–ray continuum sources, or they may have strong emission lines. Usually but not always these properties go together as in radio loud quasars. However, there appears to exist a class of objects which resemble quasars in radio structure and brightness – have strong flat spectrum cores but appear fainter than would be suggested by their radio brightness – unidentified on sky surveys (Zensus & Porcas, 1985, in J. Dyson, ed, AGN). These are called ‘optically quiet quasars’ (OQQs).

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Tamura, S. y I. Kazes. "Detection of OH Maser Emission at 1667 MHz from IC 4997". Symposium - International Astronomical Union 131 (1989): 209. http://dx.doi.org/10.1017/s0074180900138203.

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We report the first detection of OH emission at 1667 MHz from a planetary nebula, IC 4997 (Figure 1). OH emission in satellite line of 1612 MHz was detected already from planetary nebulae not only Vy 2-2 (Davis and Seaquist 1979), but also two IRAS objects which were distinguished from OH/IR stars as planetary nebulae (Pottasch et al 1987). OH observations of IC 4997 have been carried out with the large radio telescope at Nançay, France. Highly resolved optical emission lines were obtained at the Okayama Astrophysical Observatory, Japan.

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Miroshnichenko, Anatoly S. "MWC 314 – A new galactic B[e] supergiant". Symposium - International Astronomical Union 162 (1994): 396–97. http://dx.doi.org/10.1017/s0074180900215489.

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We present a new study of MWC 314 = BD +14°3887 – a poorly investigated object with strong emission lines and IR excesses. Merrill (1927) payed attention to it because of the presence of hydrogen and Fe II emissions in its spectrum. Swensson (1942) also detected interstellar lines H and K CaII and 4430 Å band, Balmer emissions from Hα to H8, NaI 5890 and 5896 Å emissions and estimated its spectral type as gG2-3 or dG4-5 from the SED in continuum, and B2 from the excitation degree. Photospheric lines and spectral features of late-type stars were not observed. Allen (1973) noted that the object's SED corresponds to that of a late-type star but it might be a symbiotic system or a reddened normal star. The IRAS fluxes were obtained only at 12 and 25 μm. The object is unknown as a radio source. From this we can conclude that this system consists of, at least, a hot star surrounded by a gaseous envelope.

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Más fuentes

Tesis sobre el tema "IR and radio emission lines"

Herrera, Contreras Cinthya Natalia. "How do the large-scale dynamics of galaxy interactions trigger star formation in the Antennae galaxy merger?" Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00800077.

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The Antennae (22 Mpc) is one of the most well-known mergers in the nearby Universe. Its distance allow us to observe and study the gas at the scales of stellar cluster formation. It is an ideal source to understand how the galaxy dynamics in mergers trigger the formation of stars. Most of the stars in the Antennae are formed in compact and massive stellar clusters, dubbed super-star clusters (SSCs). The most massive (>106 M⊙) and youngest (<6 Myr) SSCs are located in the overlap region, where the two galaxies collide, and are associated with massive (several 108 M⊙) and super-giant (few hundred of pc) molecular complexes (SGMCs). The formation of SSCs must involve a complex interplay of merger-driven gas dynamics, turbulence fed by the galaxy interaction, and dissipation of the kinetic energy of the gas. Within SGMCs, a hierarchy of structures must be produced, including dense and compact concentrations of molecular gas massive enough to form SSCs, pre-cluster clouds (PCCs). For star formation to occur, the mechanical energy of PCCs must be radiated away to allow their self-gravity to locally win over their turbulent gas pressure. Specific tracers of turbulent dissipation are therefore key inputs to test the validity of this theoretical scenario. In my thesis, I studied the Antennae overlap region. My work is based on observations with the SINFONI spectro-imager at the VLT, which includes H2 rovibrational and Brγ line emission, and with ALMA, which includes the CO(3-2) line and dust continuum emission. Both data-sets have the needed sub-arcsecond angular resolution to resolve the scales of SSC formation. The spectral resolutions are enough to resolve motions within SGMCs. Combining CO and H2 line emission is key in my PhD work. I use CO as a tracer of the distribution and kinematics of the molecular gas, and H2 as a tracer of the rate at which the gas mechanical energy is dissipated.My thesis focuses on diverse sources in the Antennae overlap region which trace different stages of star formation: the gathering of mass necessary to form SGMCs, the formation of PCCs within SGMCs and the disruption of a parent cloud by a newly formed SSC. I show that at each stage turbulence plays a key role. I found that the kinetic energy of the galaxies is not thermalized in large scale shocks, it drives the turbulence in the molecular ISM at a much higher level than what is observed in the Milky Way. Near-IR spectral diagnostics show that, outside of SSCs embedded in their parent clouds, the H2 line emission is powered by shocks and traces the dissipation of the gas turbulent kinetic energy. I relate the H2 emission to the loss of kinetic energy required to form gravitationally bound clouds. This interpretation is supported by the discovery of a compact, bright H2 source not associated with any known SSC. It has the largest H2/CO emission ratio and is located where the data show the largest velocity gradient in the interaction region. To our knowledge, this is the first time that an extragalactic source with such characteristics is identified. We would be witnessing the formation of a cloud massive enough to form a SSC. The data also allow us to study the disruption of a parent molecular cloud by an embedded SSC. Its matter is loosely bound and its gravity would be supported by turbulence, which makes it easier for feedback to disrupt the parent cloud. I end my manuscript presenting two projects. I propose to establish additional energy dissipation tracers observable with ALMA, which gives us the high spatial and spectral resolution needed to isolate scales at which clusters form. This is a Cycle 1 proposal accepted in first priority. I also plan to expand my work to other nearby extragalactic sources by investigating the turbulence-driven formation of stars in different extragalactic sources by combining near-IR and submillimeter observations.

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Short-Long, Jessica. "CORRELATION BETWEEN EMISSION LINES AND RADIO LUMINOSITIES OF ACTIVE GALACTIC NUCLEI". UKnowledge, 2018. https://uknowledge.uky.edu/physastron_etds/55.

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Radio-loud active galactic nuclei (AGN) are one class of objects associated with accretion activity onto supermassive black holes in centers of massive galaxies. They are believed to be in a radiatively-inefficient accretion mode with low accretion rate. To understand this accretion mode, it is important to measure its radiative output at high energies (> 13.6eV), which can be traced through optical emission lines. However, little is known about their true radiative output. This is because no correlation between optical emission-line and radio luminosity has been found for the majority of low-luminosity radio AGN, which are often classified as low-excitation radio galaxies, or Fanaroff-Riley Class I (FR-I) radio galaxies. We demonstrate that most of the line emission found in these galaxies is not powered by the central AGN, but likely powered by some old stellar population. Only when this component is subtracted or otherwise taken into account can we estimate the true line emission associated with the AGN. These emissions may show interesting correlations with the radio luminosities in some cases.

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Humphrey, Andrew James. "Quantitative spectroscopy of the ultraviolet and optical emission lines from high redshift radio galaxies". Thesis, University of Hertfordshire, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.421273.

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Rice, Johnathan Scott. "The Transition From Diffuse to Dense Molecular Clouds". University of Toledo / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1534945134382193.

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De, Witt Aletha. "Radio astronomy techniques : the use of radio instruments from single dish radio telescopes to radio interferometers". Thesis, 2012. http://hdl.handle.net/10500/7046.

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New radio telescopes under development, will significantly enhance the capabilities of radio astronomy in the Southern Hemisphere. South Africa, in particular, is actively involved in the development of a new array (MeerKAT) as well as in the expansion of existing very long baseline interferometer arrays in the south. Participation in these new developments demands a thorough understanding of radio astronomy techniques, and data analysis, and this thesis focusses on two projects with the aim of gaining such experience. The Southern Hemisphere very long baselines array is not well served with calibrator sources and there are significant gaps in the present calibrator distribution on the sky. An adequately dense, well distributed, set of strong, compact calibrator or reference sources is needed. With this in mind, observations using the Southern Hemisphere long baseline array were conducted to investigate a sample of candidate calibrator sources. The compactness of the sources was investigated and new potential calibrators have been identified. Single antenna radio spectroscopy of OH masers has identified sources of 1720 MHz emission associated with supernova remnants at the shock interface between the expanding supernova remnant and a molecular cloud. Models indicate that these masers are shock excited and can only be produced under tight physical constraints. Out ows from newly-formed stars create nebulous regions known as Herbig-Haro objects when they interact with the surrounding medium, and these regions are potentially similar to those seen in supernova remnants. If conditions behind the shock fronts of Herbig-Haro objects are able to support 1720-MHz OH masers they could be a useful diagnostic tool for star formation. A survey toward Herbig-Haro objects using a single-dish radio telescope did detect 1720-MHz OH lines in emission, but neither their spectral signature nor follow-up observations with the Very Large Array showed evidence of maser emission.
Mathematical Sciences
Ph.D. (Astronomy)

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Capítulos de libros sobre el tema "IR and radio emission lines"

Koekemoer, A. M. y G. V. Bicknell. "Shock Excitation of Emission Lines in Radio Galaxies". En Extragalactic Radio Sources, 473–74. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-009-0295-4_171.

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Martin-Pintado, J., R. Bachiller y C. Thum. "Radio Recombination Line Maser Emission in MWC349". En Radio Recombination Lines: 25 Years of Investigation, 161–67. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-009-0625-9_15.

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Bicknell, G. V., M. A. Dopita y C. P. O’dea. "Shock Excitation of Emission Lines and the Relation to GPS Sources". En Extragalactic Radio Sources, 469–70. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-009-0295-4_169.

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Allington-Smith, J. R. "Emission Lines and Star Formation in Radio Galaxies". En The Epoch of Galaxy Formation, 383–85. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-0919-9_50.

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Churchwell, E., C. M. Walmsley, D. O. S. Wood y H. Steppe. "Radio Recombination Line Emission from Ultracompact HII Regions". En Radio Recombination Lines: 25 Years of Investigation, 83–92. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-0625-9_7.

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Tarafdar, S. P. y K. M. V. Apparao. "Recombination emission from CII-region around Be-Stars". En Radio Recombination Lines: 25 Years of Investigation, 169–73. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-0625-9_16.

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Thompson, Rodger I. "Near Infrared Emission Lines in the Active Nuclei of Spiral Galaxies". En Spiral Galaxies in the Near-IR, 308–14. Berlin, Heidelberg: Springer Berlin Heidelberg, 1996. http://dx.doi.org/10.1007/978-3-540-49739-4_49.

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Penn, M. J., J. R. Kuhn, J. Arnaud, D. L. Mickey y B. J. Labonte. "Coronal Electron Density Measurements Using the Near-Ir [Fe XIII] Emission Lines". En Mass Supply and Flows in the Solar Corona, 185–88. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-0930-7_32.

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Goss, W. M., R. D. Ekers, R. A. E. Fosbur, C. N. Tadhunter y I. J. Danziger. "The extended structure of the radio galaxy PKS 0521-36: radio polarization and optical emission lines". En Hot Spots in Extragalactic Radio Sources, 75–76. Berlin, Heidelberg: Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/bfb0036016.

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Loeb, Abraham y Steven R. Furlanetto. "Other Probes of the First Galaxies". En The First Galaxies in the Universe. Princeton University Press, 2013. http://dx.doi.org/10.23943/princeton/9780691144917.003.0013.

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This chapter discusses several other ways to probe structures during the cosmic dawn. It first turns to secondary anisotropies of the cosmic microwave background, which are generated as the photons passed through gas during the cosmic dawn. Next, the chapter turns to diffuse backgrounds from the cosmic dawn, which typically include galactic emission lines, ranging from CO lines in the radio to the Lyman-α‎ line itself. Finally, the chapter observes that fossil structure from early galaxies remains in (or can be deduced from) the Milky Way or other nearby entities in the Local Group. This fossil structure includes the residual effects of feedback on the small satellite galaxies or globular clusters of the Milky Way, old low-mass stars that may have formed during the cosmic dawn and survive inside the Milky Way (or its halo), and remnant signatures of the early merger history of the Milky Way.

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Actas de conferencias sobre el tema "IR and radio emission lines"

Eracleous, Michael y Jules P. Halpern. "Double-peaked emission lines in radio-loud AGNs". En Accretion processes in astrophysical systems: Some like it hot! - eigth astrophysics conference. AIP, 1998. http://dx.doi.org/10.1063/1.55867.

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Levy, Y., M. Lev y V. Ovcharenko. "Infrared Radiation From Turbojet Exhaust Plume". En ASME Turbo Expo 2007: Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-27379.

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In recent years, there was an increasing interest in aircraft IR signature as an effective passive means of detecting and locking on to an aircraft. There are two main sources of the aircraft IR emission: engine-fuselage layout and gaseous exhaust plume. The size of aircraft plume is several times more than the size of aircraft. The present work focuses on the exhaust plume. The relatively high temperature plume ejected from the nozzle is a mixture of several species that are products of hydrocarbon fuel combustion under excess air condition: CO2, H2O, CO, O2, and N2. Experimental investigation of IR radiation from exhaust gases of a small turbojet engine was conducted in a micro jet engine SR-30 by Turbine Technologies, Ltd. The compact engine features a centrifugal flow compressor, reverse flow annular combustor and an axial flow turbine stage. The SR-30 follows the fundamental Brayton gas turbine cycle. The engine is operated at different regimes with various flow rates of air and kerosene. Measurements were obtained with engine operating at global equivalence ratio of about 0.23. The IR radiation images of the exhaust flow were obtained by a thermocamera equipped with a narrow bandpass filter that falls on the CO2 fundamental band emission. Temperature profiles were measured by a thermocouple in the exhaust flow. An in-house computer program was developed to calculate the IR emission from optically thick gas object and it takes into account the self-absorption of the IR radiation along a line-of-sight. An essential feature of the calculation is the fact that the optical path is non-isothermal. The typical IR spectrum of a turbo-jet engine exhaust flow was simulated using the developed computer program. The calculations allow prediction of “apparent” plume temperatures measured by the IR camera. The calculated results were compared with the experimental measurements and a good agreement was found.

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Goldstein, Neil, Brian Gregor, Jamine Lee, Stephen K. Kramer, Stuart Kozola y Kenneth J. Semega. "IR Structured Emission-Based Speciation, Thermometry, and Tomography of CO and H2O in High-Pressure Combustors". En ASME Turbo Expo 2006: Power for Land, Sea, and Air. ASMEDC, 2006. http://dx.doi.org/10.1115/gt2006-90899.

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Passive optical probes and high-resolution emission spectroscopy are used to provide a general-purpose real-time temperature and chemical species sensing capability. Probes can be inserted in the combustor, at the turbine inlet, in the augmenter, or at the engine exit with application as an engine development diagnostic tool that provides spatially resolved measurements of the key combustion parameters: temperature, CO concentration, and H2O concentration. Multiple probes are arrayed to collect the emitted infrared radiation over different views of the hot gas path. Line-of-sight averaged concentrations and temperatures are determined by spectral analysis of the emitted radiation along each line of sight (LOS). Spatial profiles may also be determined by simultaneous analysis of overlapping lines of sight. The collected infrared spectra contain optically thin and optically thick features that reflect the effects of emission and absorption within the combustion region. The known spectral structure of the component spectra can be used for the automated interpretation of the observed radiance spectra in terms of concentrations and temperatures along the line of sight, and in specific volume elements of overlapping lines of sight. In this work, we present measurements of atmospheric-pressure flames and high-pressure combustors and describe the formalism for fitting the observed spectra to a basis of simulated spectra to extract estimates of concentrations and temperatures. The spectral basis is constructed using a multilayer radiation transport model, in which each line-of-sight or measurement volume is divided into segments of uniform concentration and temperature. The observed radiance emanating from each segment is calculated as a function of the local physical variables. The collection of observed data, which contains a highly structured emission spectrum over each line of sight, is fit to the spectral basis to extract line-of-sight averaged physical properties, or in the case of spatial reconstruction, volume-averaged properties for each of the overlap regions.

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Levy, Yeshayahou, Vladimir Erenburg, Yakov Goldman, Valery Sherbaum y Vitaly Ovcharenko. "CFD Assisted Design of Micro GT Combustor". En ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59448.

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The work presents the development of a micro-combustor design, where the combustion process was simulated by CFD and tested experimentally. The inner diameter of the first model was 5.5 mm, the exit diameter 2.5 mm, and the length 24.5 mm. The designed heat release was 200W. Some modifications of the microcombustor were studied. Three-dimensional model for combustion simulations was used. The ‘conjugate heat transfer’ methodology, based on a simultaneous solution of the heat transfer equations for gas and combustor walls, coupled with equations for the working fluid, enabled the prediction of the combustor wall temperatures. To check model convergence 2 simulations with different number of cells were carried out. Effect of heat radiation was also studied by the CFD simulation. The fuel is methane and stoichiometric ratio was simulated. Reactive flow calculations were carried out with a two-step reaction. The analysis of the simulated results was based on the obtained velocity profiles, concentration and temperature distributions within the liner. Preliminary simulations showed that the first combustor design had inefficient combustion. The reason was poor mixing of methane and air inside the mixing chamber and deterioration of the combustion by dilution holes. Consequently, the combustor design was modified and simulated. The simulation showed that the modification significantly improved mixing and combustion process and better combustion was provided. Due to complexity associated with performing combustion experiments in such small dimensions, only limited data could be recorded. A small combustor was manufactured and tests and demonstrated its successful operation. Measurements of temperature and optical UV-VIS-IR - emissions at the combustor exit were obtained. The experimental and simulation results are compared and a good qualitative agreement was found between the experiments and the predicted values.

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Hilton, Moira, Alan H. Lettington y Chris W. Wilson. "Gas Turbine Exhaust Emissions Monitoring Using Non-Intrusive Infrared Spectroscopy". En ASME 1997 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/97-gt-180.

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Infrared (IR) spectra of the exhaust emissions from a static gas turbine engine have been studied using Fourier Transform (FT) spectroscopic techniques. Passive detection of the infrared emission from remote (range ∼ 3 m) hot exhaust gases was obtained non-intrusively using a high spectral resolution (0.25 cm−1) FTIR spectrometer. Remote gas temperatures were determined from their emission spectra using the total radiant flux method or by analysis of rotational line structure. The HITRAN database of atmospheric species was used to model the emission from gas mixtures at the relevant temperatures. The spatial distribution of molecular species across a section transverse to the exhaust plume −10 cm downstream of the jet pipe nozzle was studied using a tomographic reconstruction procedure. Spectra of the infrared emission from the plume were taken along a number of transverse lines of sight from the centreline of the engine outwards. A mathematical matrix inversion technique was applied to reconstruct the molecular concentrations of CO and CO2 in concentric regions about the centreline. Quantitative measurements of the molecular species concentrations determined non-intrusively were compared with results from conventional extractive sampling techniques.

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Anderson, Thomas N., Rodolfo Barron-Jimenez, Jerald A. Caton, Robert P. Lucht, Sukesh Roy, Michael S. Brown, James R. Gord, Thomas Walther, Ian Critchley y Luis Flamand. "Diode-Laser-Based Sensor Measurements of Nitric Oxide and Carbon Monoxide in Combustion Exhaust Streams". En ASME 2003 Heat Transfer Summer Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/ht2003-47532.

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All-solid-state continuous-wave (cw) laser systems for ultraviolet (UV) absorption measurements of the nitric oxide (NO) molecule and mid-infrared (IR) absorption measurements of carbon monoxide (CO) were developed and demonstrated. For the NO sensor, 250 nW of tunable cw UV radiation at 226.8 nm is produced by sum-frequency-mixing in a beta-barium borate crystal. For the CO sensor, 2μW of tunable cw IR radiation at 4.5 μm is produced by difference-frequency mixing in a periodically-poled lithium niobate crystal. A tunable external-cavity diode laser (ECDL) provides one of the fundamental beams for both processes so that the wavelength of the generated UV/IR can be tuned over NO/CO absorption lines to produce a fully resolved absorption spectrum. The sensors were used for measurements in the exhaust stream of an operating auxiliary power unit (APU) gas turbine engine and a well-stirred reactor (WSR). During these tests, NO was measured in the exhaust at levels below 10 ppm. For measurements at levels above 20 ppm, the NO emission levels obtained using the new sensor agreed with the results of probe sampling chemiluminescent analyzer results to within 10%. A detection limit of 0.8 ppm of per meter path length at 1000 K is estimated for the NO sensor. Measurements with the CO sensor demonstrated an agreement with extractive probe sampling to within 15%. The estimated detection limit of the CO sensor is a few ppm per meter path length at 1000 K.

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