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Sample records for hii region gum31

  1. Star forming regions towards Gum 31: distribution of the molecular gas

    NASA Astrophysics Data System (ADS)

    Vazzano, M. M.; Cappa, C. E.; Vasquez, J.; Rubio, M.

    2015-08-01

    We analyze the distribution of the molecular gas associated with IRAS and 2MASS sources, young stellar objects linked to the Hii region Gum31. We based our studies on observations obtained with the APEX telescope, located in the north of Chile. We used observations of different CO isotopologues, CS(7-6) and HCO(4-3) lines. The sources are located on the edge of the Gum31 Hii region, whose shock front substantially affects the morphology of their molecular environs. The observations revealed that in the surroundings of the sources there is molecular gas associated with the nebula, which is shown by the CO(3-2) emission, with small high density clumps detected in CO(3-2).

  2. The environs of the H II region Gum 31

    NASA Astrophysics Data System (ADS)

    Cappa, C.; Niemela, V. S.; Amorín, R.; Vasquez, J.

    2008-01-01

    Aims:We analyze the distribution of the interstellar matter in the environs of the H ii region Gum 31, excited by the open cluster NGC 3324, located in the complex Carina region, with the aim of investigating the action of the massive stars on the surrounding neutral material. Methods: We use neutral hydrogen 21-cm line data, radio continuum images at 0.843, 2.4 and 4.9 GHz, 12CO(1-0) observations, and IRAS and MSX infrared data. Results: Adopting a distance of 3 kpc for the H ii region and the ionizing cluster, we derived an electron density of 33±3 cm-3 and an ionized mass of (3.3±1.1)×103 M⊙ based on the radio continuum data at 4.9 GHz. The H i 21-cm line images revealed an H i shell surrounding the H ii region. The H i structure is 10.0 ± 1.7 pc in radius, has a neutral mass of 1500 ± 500 M⊙, and is expanding at 11 km s-1. The associated molecular gas amounts to (1.1 ± 0.5)×105 M⊙, being its volume density of about 350 cm-3. This molecular shell could represent the remains of the cloud where the young open cluster NGC 3324 was born or could have originated by the shock front associated with the H ii region. The difference between the ambient density and the electron density of the H ii region suggests that the H ii region is expanding. The distributions of the ionized and molecular material, along with that of the emission in the MSX band A, suggest that a photodissociation region has developed at the interface between the ionized and molecular gas. The copious UV photon flux from the early type stars in NGC 3324 keeps the H ii region ionized. The characteristics of a relatively large number of the IRAS, MSX, and 2MASS point sources projected onto the molecular envelope are compatible with protostellar candidates, showing the presence of active star forming regions. Very probably, the expansion of the H ii region has triggered stellar formation in the molecular shell.

  3. Turbulence in HII regions

    NASA Astrophysics Data System (ADS)

    O'dell, C. R.

    1986-10-01

    It has been known for many decades that the Reynolds number in HII regions must be very high and that the corresponding fine scale flow must be turbulent. Even though the theoretical relation between turbulent element separation and random velocity was derived by Kolmogoroff over forty years ago, there have been only a few attempts to test this theory and its corresponding assumptions. An attempt by Munch for M42 with marginal velocity resolution lead to ambiguous results, although more recent studies by Jean Rene Roy and his colleagues have been more credible. The internal velocities of a number of HII regions were systematically studied and the theory was tested with considerable certainty. The results should be important for the determination of the energy balance of HII regions and the relation of small scale motion to the process of star formation.

  4. The effects of HII regions

    NASA Astrophysics Data System (ADS)

    Dale, J. E.

    2016-05-01

    Recent work on the effects of HII regions on giant molecular clouds (GMCs) and their embedded clusters is discussed. Although the dispersive effects of ionising radiation on clouds, particularly massive ones with high escape velocities, is rather modest, it is argued that it is still a vitally important process in the evolution of GMCs and clusters. It is able to drive turbulence on GMC scales, to set the optical emergence timescales of at last ˜ 103 M⊙ clusters, and has a strong influence on the large-scale energy and momentum input of supernovae by determining their detonation environments.

  5. The Southern HII Region Discovery Survey

    NASA Astrophysics Data System (ADS)

    Wenger, Trey; Miller Dickey, John; Jordan, Christopher; Bania, Thomas M.; Balser, Dana S.; Dawson, Joanne; Anderson, Loren D.; Armentrout, William P.; McClure-Griffiths, Naomi

    2016-01-01

    HII regions are zones of ionized gas surrounding recently formed high-mass (OB-type) stars. They are among the brightest objects in the sky at radio wavelengths. HII regions provide a useful tool in constraining the Galactic morphological structure, chemical structure, and star formation rate. We describe the Southern HII Region Discovery Survey (SHRDS), an Australia Telescope Compact Array (ATCA) survey that discovered ~80 new HII regions (so far) in the Galactic longitude range 230 degrees to 360 degrees. This project is an extension of the Green Bank Telescope HII Region Discovery Survey (GBT HRDS), Arecibo HRDS, and GBT Widefield Infrared Survey Explorer (WISE) HRDS, which together discovered ~800 new HII regions in the Galactic longitude range -20 degrees to 270 degrees. Similar to those surveys, candidate HII regions were chosen from 20 micron emission (from WISE) coincident with 10 micron (WISE) and 20 cm (SGPS) emission. By using the ATCA to detect radio continuum and radio recombination line emission from a subset of these candidates, we have added to the population of known Galactic HII regions.

  6. Turbulence in HII regions: New results

    NASA Astrophysics Data System (ADS)

    Joncas, Gilles

    HII regions were the first interstellar objects where scale dependant brightness and velocity fluctuations were indentified (von Hoerner 1951, Courtes 1955, Munch 1958). The study of turbulent motions in HII regions was then forgotten for many years until the work of Joncas and O'Dell which started in 1985. I will present my deductions stemming from the analysis of the velocity fields of 6 HII regions (Sh 142, M17, Sh 158, Sh 170 and Sh 212). New data from the radial velocity AND density fields of the HII region Sh 269 will also be shown. The analysis was done using the well known two-point correlation functions. However I innovated by using the higher order structure functions. PDF calculations were also done hinting at the presence of intermittency in Sh 269.

  7. A panchromatic study of extragalactic HII regions

    NASA Astrophysics Data System (ADS)

    Peeters, Els; Allamandola, Louis; Bernard-Salas, Jeronimo; Tielens, Alexander

    2006-05-01

    Star formation rates (SFR) are considered the key to understanding galaxy formation and evolution. All wavelength regions have been exploited to determine the SFR by studying massive star forming regions at all redshifts. Indeed, traditionally, SFR in galaxies are determined based upon H alpha, FIR and the UV. In recent years, MIR tracers of star formation activity of galaxies have been explored but their quantitative use is still under debate. Here, we propose to obtain Spitzer-IRS SL-LL observations of a sample of well-characterized HII regions in two galaxies, M33 and M83. These HII regions span a wide range in galactocentric radii and hence metallicity. These metallicities have been determined through an earlier, unrelated investigation (PID 3412 & 20057; PI Rubin). The proposed observations are complementary to existing auxiliary data and are in fact the missing link for a panchromatic view of individual extragalactic HII regions. This proposal will provide, for the first time, a quantitative estimate of the effects on the MIR characteristics of extagalactic HII regions of parameters such as the metallicity, the hardness of the stellar radiation field (NeIII/NeII and/or SIV/SIII ratios), density (NeIII and/or SIII line ratios), stellar luminosity (radio, H alpha) can be systematically investigated. Hence, the proposed observations form the basis for a systematic study of PAH and dust properties, their dependency on the physical conditions of the environment and their usefulness as a quantitative tracer for star formation. As a result, this study will influence the interpretation of star forming regions on small and large scales and distances out to the era of vigorous star formation activity.

  8. Python Program to Select HII Region Models

    NASA Astrophysics Data System (ADS)

    Miller, Clare; Lamarche, Cody; Vishwas, Amit; Stacey, Gordon J.

    2016-01-01

    HII regions are areas of singly ionized Hydrogen formed by the ionizing radiaiton of upper main sequence stars. The infrared fine-structure line emissions, particularly Oxygen, Nitrogen, and Neon, can give important information about HII regions including gas temperature and density, elemental abundances, and the effective temperature of the stars that form them. The processes involved in calculating this information from observational data are complex. Models, such as those provided in Rubin 1984 and those produced by Cloudy (Ferland et al, 2013) enable one to extract physical parameters from observational data. However, the multitude of search parameters can make sifting through models tedious. I digitized Rubin's models and wrote a Python program that is able to take observed line ratios and their uncertainties and find the Rubin or Cloudy model that best matches the observational data. By creating a Python script that is user friendly and able to quickly sort through models with a high level of accuracy, this work increases efficiency and reduces human error in matching HII region models to observational data.

  9. Finding Distant Galactic HII Regions

    NASA Astrophysics Data System (ADS)

    Anderson, L. D.; Armentrout, W. P.; Johnstone, B. M.; Bania, T. M.; Balser, Dana S.; Wenger, Trey V.; Cunningham, V.

    2015-12-01

    The WISE Catalog of Galactic H ii Regions contains ˜2000 H ii region candidates lacking ionized gas spectroscopic observations. All candidates have the characteristic H ii region mid-infrared morphology of WISE 12 μ {{m}} emission surrounding 22 μ {{m}} emission, and additionally have detected radio continuum emission. We here report Green Bank Telescope hydrogen radio recombination line and radio continuum detections in the X-band (9 GHz; 3 cm) of 302 WISE H ii region candidates (out of 324 targets observed) in the zone 225^\\circ ≥slant {\\ell }≥slant -20^\\circ , | {\\text{}}b| ≤slant 6^\\circ . Here we extend the sky coverage of our H ii region Discovery Survey, which now contains nearly 800 H ii regions distributed across the entire northern sky. We provide LSR velocities for the 302 detections and kinematic distances for 131 of these. Of the 302 new detections, 5 have ({\\ell },{\\text{}}b,v) coordinates consistent with the Outer Scutum-Centaurus Arm (OSC), the most distant molecular spiral arm of the Milky Way. Due to the Galactic warp, these nebulae are found at Galactic latitudes >1° in the first Galactic quadrant, and therefore were missed in previous surveys of the Galactic plane. One additional region has a longitude and velocity consistent with the OSC but lies at a negative Galactic latitude (G039.183-01.422 -54.9 {km} {{{s}}}-1). With Heliocentric distances >22 kpc and Galactocentric distances >16 kpc, the OSC H ii regions are the most distant known in the Galaxy. We detect an additional three H ii regions near {\\ell }≃ 150^\\circ whose LSR velocities place them at Galactocentric radii >19 kpc. If their distances are correct, these nebulae may represent the limit to Galactic massive star formation.

  10. The WISE Catalog of Galactic HII Regions Website

    NASA Astrophysics Data System (ADS)

    Anderson, Loren D.

    2014-01-01

    The WISE Catalog of Galactic HII Regions has catalogued over 8000 objects, including all approximately 2000 known Galactic HII regions and over 6000 HII region candidates. As part of this effort, we created a flexible and interactive website to showcase the catalog contents and to allow quick access to the data. This website uses Google Fusion Tables and the Google Maps interface. We will detail the steps used to create the site, explain the user interface, and describe how other researchers can easily build off our experience to create similar sites of their own.

  11. Photoionization models of the CALIFA HII regions

    NASA Astrophysics Data System (ADS)

    Morisset, C.; Delgado-Inglada, G.; Sánchez, S. F.

    2016-06-01

    We present here a short summary of a forthcoming paper on photoionization models based on CALIFA observations of HII regions. For each of the ˜ 20,000 sources of the CALIFA H ii regions catalog, a grid of photoionization models is computed assuming the ionizing SED being described by the underlying stellar population obtained from spectral synthesis modeling. The nebular metallicity (associated to O/H) is defined using the classical strong line method O3N2. The remaining free parameters are the abundance ratio N/O and the ionization parameter U, which are determined by looking for the model fitting [N II]/Hα and [O III]/Hβ. The models are also selected to fit [O II]/Hβ. This process leads to a set of ˜ 3,200 models that reproduce simultaneously the three observations. We determine new relations between the nebular parameters, like the ionization parameter U and the [O II]/[O III] or [S II]/[S III] line ratios. A new relation between N/O and O/H is obtained, mostly compatible with previous empirical determinations (and not with previous results obtained using photoionization models). A new relation between U and O/H is also determined. All the models are publicly available on the Mexican Millions Models database 3MdB.

  12. HII regions in dwarf irregular galaxies of the local group

    NASA Technical Reports Server (NTRS)

    Hodge, Paul; Lee, Myung Gyoon

    1990-01-01

    Deep, narrowband H alpha Charge Coupled Device (CCD) surveys of HII regions were carried out in several dwarf irregular galaxies in and near the local group. Data are now complete for these galaxies: NGC 6822, GR 8, IC 10, IC 1613, Sextans A, Sextans B, and Sag Irr. Observations are complete for DDO 47, 53, 167, 168 and 187. Details of some of the results for the surveys completed so far are discussed. For NGC 6822, CCD survey at H alpha resulted in the detection of 145 HII regions in the local group irregular galaxy NGC 6822. Most of them are newly detected, faint surface-brightness objects. Positions, maps and dimensions are being published elsewhere. For GR 8, a deep narrowband H alpha imaging of the nearby dwarf irregular galaxy GR 8 revealed a total of 32 HII regions. Positions, H alpha luminosities, and sizes of these objects were determined. The H alpha luminosity function has the same shape as that for more luminous galaxies, except for size of sample effects. Most HII regions detected are at the very low luminosity end of the general luminosity function. For IC 10, a deep CCD narrowband H alpha imaging of the local group dwarf irregular galaxy IC 10 revealed a total of 144 HII regions. Positions, H alpha luminosities, and sizes of these objects were determined. The H alpha luminosity function has the same shape as that for more luminous galaxies.

  13. Nonlinear Dynamics of Ionization Fronts in HII Regions

    SciTech Connect

    Mizuta, A; Kane, J O; Pound, M W; Remington, B A; Ryutov, D D; Takabe, H

    2006-04-20

    Hydrodynamic instability of an accelerating ionization front (IF) is investigated with 2D hydrodynamic simulations, including absorption of incident photoionizing photons, recombination in the HII region, and radiative molecular cooling. When the amplitude of the perturbation is large enough, nonlinear dynamics of the IF triggered by the separation of the IF from the cloud surface is observed. This causes the second harmonic of the imposed perturbation to appear on the cloud surfaces, whereas the perturbation in density of ablated gas in the HII region remains largely single mode. This mismatch of modes between the IF and the density perturbation in the HII region prevents the strong stabilization effect seen in the linear regime. Large growth of the perturbation caused by Rayleigh-Taylor-like instability is observed late in time.

  14. A grid of model HII regions for extragalactic studies

    NASA Astrophysics Data System (ADS)

    Stasińska, G.

    1990-06-01

    An extensive grid of model HII regions has been computed with the photoionization code PHOTO. This grid is mainly intended to provide a tool for extragalactic HII regions studies. The abundances vary from twice to 1/100th solar. The ionizing stars effective temperatures reach 55,000 K, and their number varies from 1 to 10,000. Computed line intensities in the infrared, visible and ultraviolet ranges are displayed, together with the mean ionic fractions and the mean electron temperatures for ions of interest.

  15. Stability of Small Grains in HII Regions and Reflection Nebulae

    NASA Technical Reports Server (NTRS)

    Werner, M. W.; Gauthier, T. N., III; Cawlfield, T.

    1993-01-01

    We have analyzed IRAS data to assess the relative amounts of small and large grains in HII regions and reflection nebulae. Our most important finding is that no evidence for small grain destruction is seen in reflection nebulae, even for [high] values of the radiation energy density at which significant grain destruction apparently occurs in HII regions. This suggests that it is not only the total radiant energy density but also the energy per photon which determines the stability of small grains in astrophysical environments.

  16. A multiwavelength study of Galactic HII region S297

    NASA Astrophysics Data System (ADS)

    Mallick, K. K.; Ojha, D. K.; Samal, M. R.; Pandey, A. K.; Ghosh, S. K.; Bhatt, B. C.; Tamura, M.

    Sharpless 297 (S297), an optically visible classical HII region, at a distance of 1.1 kpc (Bica et al. 2003), is located in Canis Major. Here, we present the preliminary results of this Galactic HII region. Optical observations were carried out with the 2.01 m Himalayan Chandra Telescope (HCT), Hanle (Ladakh) and the 2 m IUCAA Girawali Observatory (IGO) telescope, Pune. Near-infrared (NIR) observations in JHK_s bands were taken with the 1.4 m IRSF telescope at South Africa. The radio continuum observations were carried out with the GMRT at 1280 MHz and 610 MHz.

  17. The Ultraviolet Emission Spectra of AN HII Region

    NASA Astrophysics Data System (ADS)

    Cox, Nancy

    1991-07-01

    ONE OF THE ADVANTAGES OF THE NEW INSTRUMENTS SUCH AS THE HUBBLE SPACE TELESCOPE IS TO BE ABLE TO STUDY THE UNIVERSE AT WAVELENGTHS PREVIOUSLY UNOBSERVABLE FROM UNDER THE EARTH'S ATMOSPHERE. ONE THE THESE IS THE UV REGION OF THE STECTRUM. USING HST'S FOS, I WOULD LIKE TO TAKE A UV SPETRUM OF AN HII REGION, M8, THE LAGOON NEBULA (HOURGLASS REGION). HII REGIONS ARE AREAS OF STARBIRTH AND ARE SAMPLES OF THE INTERSTELLAR MATTER OUT OF WHICH STARS ARE BEING BORN. HOT, YOUNG O STARS WHICH RADIATE STRONGLY IN THE UV ARE EMBEDDED IN M8. MANY EMSSION LINES ARE EXPECTED BETWEEN 912-3300 ANGTROMS. USING WF/PC, AN IMAGE OF THE HOURGALSS WILL BE TAKEN LOOKING FOR FILIMENTARY STRUCTURE AND NEW BORN STARS.

  18. Revealing of HII-regions in Galaxies with Panoramic Spectroscopy

    NASA Astrophysics Data System (ADS)

    Hakopian, S. A.; Balayan, S. K.

    2016-06-01

    Observations intended to investigation and revealing of nodes of processes of nuclear and starforming activity in galaxies were performed via panoramic spectroscopy. Data obtained on Mrk 1050 revealed evidence of starforming activity also outside the central engine of high surface brightness. Two small HII-regions, being likely a part of the chain, are located in the part of the spiral branch coming from the nucleus part.

  19. Dust continuum spectra from model HII regions

    NASA Technical Reports Server (NTRS)

    Aannestad, P. A.; Emery, R. J.

    1989-01-01

    The infrared spectrum emitted by nebular dust, heated by the ionizing stars in H II blisters and spherical H II regions, is calculated for various model parameters. Absorption of the non-ionizing radiation in a neutral layer is included. Heating by the Lyman alpha photon field is taken into account. The dust is composed of silicate and graphite grains, and evaporation of the grains in the inner region is considered. The models are presented with a view to interpretation of infrared observations of dusty H II regions and can be applied directly to the infrared astronomy satellite survey data. The continuum emission is compared with calculated fine structure line emission.

  20. Radiofrequency Mapping of Compact HII Regions: The RCW95 Complex

    NASA Astrophysics Data System (ADS)

    Barres de Almeida, U.; Abraham, Z.; Roman-Lopes, A.

    2006-06-01

    We present a 2'-resolution, 43 GHz continuum map of the free-free radio emission of the complex RCW95 made with the 14-meter antennae of the Itapetinga radio observatory in Brazil. RCW95 is a small cloud (10'×10') with coordinates α = 15^{h}44^{m}43^{s} and δ = - 54°05'54'', associated with the radio source G326.7+0.6 and identified as an optical HII region by Rodgers et al. (1960). The region encloses three strong IRAS point sources (IRAS 15408-5356, 15411-5352 and 15412-5359) with colours of compact HII regions. This work was motivated by recent studies of the stellar population of the IRAS source 15408 (Roman-Lopes & Abraham 2004) that revealed that the source is a site of ongoing massive star formation. Previous mapping of the region were conducted by Goss & Shaver (1970) in 5 GHz with low resolution and detected strong continuum emission in this direction, but could not resolve the individual sources. In this mapping we were able to separate the emission of each HII region, identifying the radio counterparts to the IRAS sources and deriving fluxes of 7.3+/-0.3 and 3.4+/-0.5 Jy for IRAS 15408 and 15411, respectively, and an upper limit of 2.0 Jy for the flux of IRAS15412. We could also identify the radio continuum counterpart of the methanol maser detected by Ellingsen et al. (1996), firstly associated by its discoverers with IRAS15408. Finally, we report the results of an unpublished 22.2 GHz water maser survey that resulted on the identification of 7 different emission lines associated with all three IRAS sources in the region, closing the long debate on the nature of IRAS15411-5352 and supporting evidence for IRAS15412 being another star-formation site in the region.

  1. Relic HII regions and radiative feedback at high redshifts

    NASA Astrophysics Data System (ADS)

    Mesinger, Andrei; Bryan, Greg L.; Haiman, Zoltán

    2009-11-01

    Ultraviolet (UV) radiation from early astrophysical sources could have a large impact on subsequent star formation in nearby protogalaxies, and in general on the progress of cosmological reionization. Theoretical arguments based on the absence of metals in the early Universe suggest that the first stars were likely massive, bright, yet short-lived, with lifetimes of a few million years. Here we study the radiative feedback arising from such stars using hydrodynamical simulations with transient UV backgrounds (UVBs) and persistent Lyman-Werner backgrounds (LWBs) of varying intensity. We extend our prior work in Mesinger et al., by studying a more typical region whose protogalaxies form at lower redshifts, z ~ 13-20, in the epoch likely preceding the bulk of reionization. We confirm our previous results that feedback in the relic HII regions resulting from such transient radiation is itself transient. Feedback effects dwindle away after ~30 per cent of the Hubble time, and the same critical specific intensity of JUV ~ 0.1 × 10-21ergs-1cm-2Hz-1sr-1 separates positive and negative feedback regimes. This suggests that overall feedback is fairly insensitive to the large-scale environment, overdensity and redshift-dependent halo parameters, and can accurately be modelled in this regime with just the intensity of the impinging UVB. Additionally, we discover a second episode of eventual positive feedback in haloes which have not yet collapsed when their progenitor regions were exposed to the transient UVB. When exposed to the transient UVB, this gas suffers relatively little density depletion but a significant enhancement of the molecular hydrogen abundance, thus resulting in net positive feedback. This eventual positive feedback appears in all runs, regardless of the strength of the UVB. However, this feedback regime is very sensitive to the presence of Lyman-Werner radiation, and notable effects disappear under fairly modest background intensities of JLW >~ 10-3 × 10

  2. Leaking Photons from the HII Region NGC 7538

    NASA Astrophysics Data System (ADS)

    Luisi, Matteo; Anderson, Loren D.; Balser, Dana S.; Bania, Thomas M.; Wenger, Trey

    2016-01-01

    Using data from the NRAO Green Bank Telescope and the INT Photometric H-Alpha Survey of the Northern Galactic Plane (IPHAS), we analyze the ionizing radiation that is escaping the photo-dissociation region (PDR) boundary of the HII region NGC 7538. We find extended radio continuum and radio recombination line (RRL) emission outside the PDR toward the north and east of the region. This suggests that a non-uniform PDR morphology is affecting the amount of radiation "leaking" through the PDR. We quantify the leaking photon fraction along the line of sight, and use a numerical model to estimate the leaking photon fraction in three dimensions of both radio continuum and H-alpha emission. We detect carbon RRL emission near the PDR and find a decrease in the helium-to-hydrogen ionic abundance ratio with increasing distance from the central position. This indicates a softening of the radiation field within the PDR. Using Herschel Space Observatory data, we create a dust temperature map of the region and show that small dust temperature enhancements to the north and east of NGC 7538 coincide with extended radio emission. We discuss implications for maintaining the ionization of the warm interstellar medium by HII regions.

  3. Self-similar polytropic champagne flows in HII regions

    NASA Astrophysics Data System (ADS)

    Hu, Ren-Yu; Lou, Yu-Qing

    2008-11-01

    We explore large-scale hydrodynamics of HII regions for various self-similar shock flows of a polytropic gas cloud under self-gravity and with quasi-spherical symmetry. We formulate cloud dynamics by invoking specific entropy conservation along streamlines and obtain global self-similar `champagne flows' for a conventional polytropic gas with shocks as a subclass. Molecular cloud cores are ionized and heated to high temperatures after the onset of nuclear burning of a central protostar. We model subsequent evolutionary processes in several ways and construct possible self-similar shock flow solutions. We may neglect the mass and gravity of the central protostar. The ionization and heating of the surrounding medium drive outflows in the inner cloud core and a shock travels outwards, leading to the so-called `champagne phase' with an expanding outer cloud envelope. Complementarily, we also consider the expansion of a central cavity around the centre. As the inner cloud expands plausibly due to powerful stellar winds, a cavity (i.e. `void' or `bubble') can be created around the centre, and when the cavity becomes sufficiently large, one may neglect the gravity of the central protostar. We thus present self-similar shock solutions for `champagne flows' with an expanding central void. We compare our solutions with isothermal solutions and find that the generalization to the polytropic regime brings about significant differences of the gas dynamics, especially for cases of n < 1, where n is a key scaling index in the self-similar transformation. We also compare our global polytropic self-similar solutions with numerical simulations on the expansion of HII regions. We further explore other possible dynamic evolutions of HII regions after the initiation of nuclear burning of the central protostar, for example asymptotic inflows or contractions far from the cloud centre and the ongoing infall around a central protostar. In particular, it is possible to use the downstream

  4. Infrared emission and the destruction of dust in HII regions

    NASA Astrophysics Data System (ADS)

    Pavlyuchenkov, Ya. N.; Kirsanova, M. S.; Wiebe, D. S.

    2013-08-01

    The generation of infrared (IR) radiation and the observed IR-intensity distribution at wavelengths of 8, 24, and 100 µm in the ionized hydrogen region around a young, massive star is investigated. The evolution of the HII region is treated using a self-consistent chemical-dynamical model in which three dust populations are included—large silicate grains, small graphite grains, and polycyclic, aromatic hydrocarbons (PAHs). A radiative transfer model taking into account stochastic heating of small grains and macromolecules is used to model the IR spectral energy distribution. The computational results are compared with Spitzer and Herschel observations of the RCW 120 nebula. The contributions of collisions with gas particles and the radiation field of the star to stochastic heating of small grains are investigated. It is shown that a model with a homogeneous PAH content cannot reproduce the ring-like IR-intensity distribution at 8 µm. A model in which PAHs are destroyed by ultraviolet radiation of the star, generating region HII, provides a means to explain this intensity distribution. This model is in agreement with observations for realistic characteristic destruction times for the PAHs.

  5. Evolutionary models for giant extragalactic HII regions at different metallicities.

    NASA Astrophysics Data System (ADS)

    Garcia-Vargas, M. L.; Bressan, A.; Diaz, A. I.

    1995-07-01

    We present theoretical evolutionary models for ionizing star clusters and their associated giant HII regions up to an age of 5.4Myr and metallicities between 1/20 and 2.5 times solar. These young clusters can provide the high energy photons needed to keep the regions ionized. We discuss in some detail the Wolf-Rayet and red supergiant phases, sometimes present in the early stages of the evolution of a star cluster. The spectral features characteristic of these stars, when detected and measured on the spectra of giant extragalactic HII regions (GEHR), can be used to constrain the age of the ionizing stellar population. The emergent ionizing continua of the clusters are used as input for the photoionization code CLOUDY to obtain the corresponding emission line spectra in the optical and infrared ranges. The effect of the metallicity is taken into account in the stellar evolution and atmosphere models as well as in the nebular gas producing a consistent set of models. These models can provide estimates of the mass, age and metallicity of the dominant stellar population ionizing a given GEHR solely from the analysis of its optical emission line spectrum.

  6. Measuring Magnetic Fields in Photoionized Interstellar Plasmas (HII Regions)

    NASA Astrophysics Data System (ADS)

    Spangler, Steven; Costa, Allison

    2015-11-01

    Hot luminous stars photoionize the interstellar gas around them, creating plasmas with a very high ionization fraction. In astronomical terminology, these are called HII regions. They are dynamic plasmas, expanding due to overpressure with respect to the interstellar medium. We are making diagnostic measurements to determine the strength and structure of magnetic fields in these objects. This paper presents our results on the Rosette Nebula. We diagnose the magnetic field in the Rosette by measurements of Faraday rotation on lines of sight passing through the nebula. These measurements are made with the Very Large Array radio telescope of the National Radio Astronomy Observatory. We have measurements of the rotation measure for 18 lines of sight. Values of the mean, line of sight component of the magnetic field range from about 3 to 5 microGauss. We will discuss comparison of these measurements with models for modification of the interstellar magnetic field by an HII region. This work was supported by grants AST09-07911 and ATM09-56901 from the National Science Foundation.

  7. HIIexplorer: Detect and extract integrated spectra of HII regions

    NASA Astrophysics Data System (ADS)

    Sanchez, S. F.

    2016-03-01

    HIIexplorer detects and extracts the integrated spectra of HII regions from IFS datacubes. The procedure assumes H ii regions are peaky/isolated structures with a strong ionized gas emission, clearly above the continuum emission and the average ionized gas emission across the galaxy and that H ii regions have a typical physical size of about a hundred or a few hundreds of parsecs, which corresponds to a typical projected size at the distance of the galaxies of a few arcsec for galaxies at z~0.016. All input parameters can be derived from either a visual inspection and/or a statistical analysis of the Hα emission line map. The algorithm produces a segmentation FITS file describing the pixels associated to each H ii region.

  8. Radio observations of the HII region complex RCW 95

    NASA Astrophysics Data System (ADS)

    Barres de Almeida, U.; Abraham, Z.; Roman-Lopes, A.

    The cloud RCW 95 was selected for study along with a number of other southern hemisphere regions in the galactic plane as part of a large program of search for YSOs associated with molecular clouds in the Galaxy. The project is an example of successful exploitation of large galactic surveys and combined both radio and far-IR observations. The selection of objects for study was based on data from the IRAS point source catalogue, in which we looked for sources with properties characteristic of star formation regions (SFRs). The main criteria constituted the presence of IRAS colours characteristic of compact HII regions, as according to work by Wood and Churchwell (1989) and the association with strong CS emission (using data from the catalogue of Bronfman et al. 1996). The presence of different maser species, typically found in association with SFRs, and ammonia lines was also used as an auxiliary information in the process. After selection, the stellar population of the regions were studied in the near-IR using data from both the 2MASS project and the SPTIZER satellite, allowing the construction of complete near-IR SEDs of the stars. RCW 95 is a special example of a region where the search successfully resulted in the discovery of several rich sites of star formation (Roman-Lopes and Abraham 2004 and 2006) and so, more detailed observations of the cloud were performed in radio in order to adress the structure and distribution of the compact HII regions therein. The continuum emission of the cloud was mapped in 43 GHz with a resolution of 2' and a complete water maser survey was conducted in its direction, at 22.2 GHz, with a positional accuracy of 1'; the result of these observations was a more clear picture of the structure of the compact and ultra-compact HII regions within the cloud and the discovery of more sites of star-formation that are still too obscured to be directly detected in the far-IR. In particular, the IRAS source 15412-5359 was revealed to be a

  9. Radio Observations Of The HII Region Complex RCW 95

    NASA Astrophysics Data System (ADS)

    Barres de Almeida, U.; Abraham, Z.; Roman-Lopes, A.

    2006-08-01

    In this work we studied the complex of compact HII regions RCW 95. The cloud was mapped on the radio continuum emission at 43 GHz; a survey of water lines was also conducted at 22 GHz. The observations were made with the 14-meter single-dish antennae of the Itapetinga radio observatory in Brazil, with 2' resolution at 43 GHz. For the continuum observations we made several scans in right ascension throughout the whole of the source spaced by 1' in declination, and with 45' extension in RA to allow for baseline correction. The study resulted on the identification of resolved radio continuum sources associated with all the three IRAS sources in the region: IRAS 15408-5356, 15411-5352 and 15412-5359, all with far-IR colours characteristics of CHII regions. The water line survey resulted on the positive identification of maser emission associated with the three IRAS sources, supporting the evidences for these regions to harbour massive young stars. Two other unresolved HII regions, not associated with far-IR sources, were also discovered through detailed analysis of the profiles of the radio continuum scans. Whilst the stellar content of the IRAS sources 15408-5356 and 15411-5352 have been previously studied in the near-IR (Roman-Lopes & Abraham 2004 and 2006), the stellar population associated to IRAS 15412-5359 was first studied in the near and middle-IR by us, motivated by the results obtained in radio. We used photometric data from 1 to 8 μm from 2MASS and SPITZER and identified a significant population of massive stars, including one O9V and some early-BV stars, that explain the ionization of the source.

  10. Slit observations and empirical calculations for HII regions

    NASA Astrophysics Data System (ADS)

    Fernandes, I. F.; Gruenwald, R.; Viegas, S. M.

    2005-12-01

    When analysing HII regions, a possible source of systematic error on empirically derived quantities, such as the gas temperature and the chemical composition, is the limited size of the slit used for the observations. In order to evaluate this type of systematic error, we use the photoionization code AANGABA to create a virtual photoionized region and mimic the effect of a slit observation. A grid of models was built varying the ionizing radiation spectrum emitted by a central stellar cluster, as well as the gas abundance. The calculated line surface brightness was then used to simulate slit observations and to derive empirical parameters using the usual methods described in the literature. Depending on the fraction of the object covered by the slit, the empirically derived physical parameters and chemical composition can be different from those obtained from observations of the whole object. This effect is mainly dependent on the age of the ionizing stellar cluster. The low-ionization lines, which originate in the outer layers of the ionized gas, are more sensitive to the size of the area covered by the slit than the high-ionization forbidden lines or recombination lines, because these lines are mainly produced closer to the inner radius of the nebula. For a slit covering 50 per cent or less of the total area, the measured [OIII], [OII] and [OI] line intensities are less than 78, 62 and 58 per cent of the total intensity for a young HII region (t < 3 Myr); for older objects the effect due to the slit is less significant. Regarding the temperature indicator T[OIII], the slit effects are small (usually less than 5 per cent) because this temperature is derived from [OIII] high-ionization lines. On the other hand, for the abundance (and temperature) indicator R23, which depends also on the [OII] line, the slit effect is slightly higher. Therefore, the systematic error due to slit observations on the O abundance is low, being usually less than 10 per cent, except for

  11. Formation of compact HII regions possibly triggered by cloud-cloud collision

    NASA Astrophysics Data System (ADS)

    Ohama, Akio; Torii, Kazufumi; Hasegawa, Keisuke; Fukui, Yasuo

    2015-08-01

    Compact HII regions are ionized by young high-mass star(s) and ~1000 compact HII regions are cataloged in the Galaxy (Urquhart et al. MNRAS 443, 1555-1586 (2014)). Compact HII regions are one of the major populations of Galactic HII regions. The molecular environments around compact HII regions are however not well understood due to lack of extensive molecular surveys. In order to better understand formation of exciting stars and compact HII regions, we have carried out a systematic study of molecular clouds toward compact HII regions by using the 12CO datasets obtained with the JCMT and NANTEN2 telescopes for l = 10 - 56, and present here the first results.In one of the present samples, RCW166, we have discovered that the HII region is associated with two molecular clouds whose velocity separation is ~10 km s-1 the two clouds show complimentary spatial distributions, where one of the clouds have a cavity-like distribution apparently embracing the other. We present an interpretation that the two clouds collided with each other and the cavity-like distribution represents a hole created by the collision in the larger cloud as modeled by Habe and Ohta (1992). Similar molecular distributions are often found in the other compact HII regions in the present study.A recent study by Torii et al. (2015, arXiv:1503.00070) indicates that the Spitzer bubble RCW120 was formed by cloud-cloud collision where the inside of the cavity is fully ionized by the exiting stars. RCW166, on the other hand, shows that only a small part of the cavity, the compact HII region, is ionized. We thus suggest that RCW166 represents an evolutionary stage corresponding to an earlier phase of RCW120 in the collision scenario.

  12. Ionization Parameter: A Diagnostic of Radiation Pressure Dominated HII Regions

    NASA Astrophysics Data System (ADS)

    Yeh, Sherry; Matzner, C. D.

    2011-01-01

    When irradiation is sufficiently intense, the structure of an HII region will be dominated by radiation pressure and stellar winds, rather than ionized gas pressure. This state is of considerable interest because of its role in the formation of massive stars, the disruption of giant molecular clouds, and the evolution of starburst galaxies. We discuss the usefulness of the ionization parameter U, as often derived from observed line ratios between species which exist only in ionized gas, as a diagnostic for the radiation pressure-dominated state. In ionization-bounded directions, U cannot exceed a maximum value Umax determined by equilibrium between radiation and gas pressure forces. Lower values of U will occur, however, when the pressure of shocked stellar winds is significant, or when neutral gas is broken into clumps with sufficiently small radii of curvature. Applying these considerations to a prominent ionized shell around 30 Doradus and to the inner starburst region of M82, along with Cloudy simulations, we conclude that both are dominated by a combination of radiation pressure and shocked winds.

  13. Investigation of the PAH size distribution in a compact HII region

    NASA Astrophysics Data System (ADS)

    Ohsawa, Ryou

    2013-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are excited by absorbing UV photons and emit the strong emission features in the infrared. The PAH emission features can be a good estimator of star formation rates (SFRs). On the other hand, PAHs are destroyed in harsh environments like HII regions. Two mechanisms are suggested for PAH destruction; sputtering and photo-dissociation. It is not observationally investigated which process is dominant in HII regions. We invent a method to identify the dominating destruction process in terms of the size distribution of PAHs. We propose the near-infrared imaging observations of a compact HII region M1-78 with the Gemini/NIRI. We investigate the variation in the PAH size distribution in M1-78 and discuss which destruction process is dominant in HII regions.

  14. Infrared emission and excitation in LMC HII regions

    NASA Technical Reports Server (NTRS)

    Ungerer, V.; Viallefond, F.

    1987-01-01

    The infrared excess (IRE) of the Large Magellanic Cloud (LMC) HII nebulae is found to correlate positively with the temperature of the ambient radiation field or with the He(+)/H(+) abundance ratio. This result is discussed in terms of a selective absorption of the photons in the range 504 to 912 A relative to the He ionizing photons. This interpretation may explain the paradox of finding highly excited nebulae with only relatively moderate equivalent width of their Balmer lines.

  15. Local reionization histories with a merger tree of the HII regions

    NASA Astrophysics Data System (ADS)

    Chardin, Jonathan; Aubert, Dominique; Ocvirk, Pierre

    2014-08-01

    Aims: We investigate simple properties of the initial stage of the reionization process around progenitors of galaxies, such as the extent of the initial HII region before its fusion with the UV background, and the duration of its propagation. Methods: We used a set of four reionization simulations with different resolutions and ionizing source prescriptions. By using a merger tree of the HII regions we compiled a catalog of the HII region properties. When the ionized regions undergo a major-merger event, we considered that they belong to the global UV background. From the lifetime of the region and from their volume until this moment we drew typical local reionization histories as a function of time and investigated the relation between these histories and the halo mass progenitors of the regions. We then used an average mass accretion history model (AMAH) to extrapolate the halo mass inside the region from high z to z = 0 to predict the past reionization histories of galaxies we see today. Results: We found that the later an HII region appears during the reionization period, the shorter their related lifetime is and the smaller their volume before they merge with the global UV background. Quantitatively, the duration and extent of the initial growth of an HII region is strongly dependent on the mass of the inner halo and can be as long as ~50% of the reionization epoch. We found that the more massive a halo is today, the earlier it appears and the larger is the extension and the longer the propagation duration of its HII region. Quantitative predictions differ depending on the box size or the source model: small simulated volumes are affected by proximity effects between HII regions, and halo-based source models predict smaller regions and slower I-front expansion than models that use star particles as ionizing sources. Applying this extrapolation to Milky Way-type halos leads to a maximal extent of 1.1 Mpc/h for the initial HII region that established itself in

  16. HST, UIT, and Groundbased Imaging of the Giant HII Regions in the Pinwheel Galaxy (Messier 33)

    NASA Astrophysics Data System (ADS)

    Waller, W. H.; Hodge, P. W.; Stecher, T. P.

    1994-12-01

    At a distance of 0.84 Mpc, Messier 33 is the closest galaxy harboring giant HII regions of both low and high metallicity. As such, M33 provides the ideal laboratory for investigating the degree to which metal abundance affects stellar population at the high-mass end. Moreover, by comparing the resolvable constituents of M33's giant HII regions with the resulting composite colors and emission-line properties, one can establish benchmarks for interpreting the composite light from more distant starbursting systems. Through a coordinated combination of HST, UIT, and ground-based imaging, we have begun a program of comparing the resolved and composite properties of the giant HII regions in M33. Multiple-band images of 6 giant HII regions have been recently obtained with the HST/WFPC2. At a spatial resolution of 0.4 pc, these images show the central populations to be loosely clustered, unlike the densely packed population that is seen in 30 Doradus. Photometric measurement of the UV, U, B, and V-band images indicates the presence of some extremely hot and luminous stars in all 6 of the targeted HII regions. (Photometry and derived statistics of the stars in one such region is presented by E. Malumuth et al. as a Poster in this meeting.) Ground-based imaging at Hα and other visible bands provide composite spectral indices of the HII region's ionizing luminosity and effective temperature which can be compared with the stellar constituents that are resolved in the HST images. FUV and NUV imaging with the Ultraviolet Imaging Telescope reveal diffuse knots of dust-scattered emission surrounding stellar cores, whose composite (FUV - NUV) colors provide sensitive information on the reddening. Comparison of the dereddened UV and Hα fluxes further constrain evolutionary models of the ionizing stellar populations, which in turn, can be checked against the resolved stellar properties. Progress on these investigations will be discussed.

  17. A Study of the Ionized Gas in Giant HII Regions in NGC 6822

    NASA Astrophysics Data System (ADS)

    Castañeda, H. O.; Caicedo-Ortiz, H. E.

    2011-10-01

    We present the preliminary results of a study of physical properties of the gas in the giant HII regions regions Hubble V and Hubble X located in the galaxy NGC 6822. We have created maps in Hα emission constructed from longslit spectroscopic observations, which were performed at the William Herschel Telescope, Canary Islands, using the ISIS spectrograph.

  18. Not Your Grandmother's HII Regions: An X-ray Tour of Massive Star-forming Regions

    NASA Astrophysics Data System (ADS)

    Townsley, Leisa K.

    2006-09-01

    Chandra and XMM-Newton are providing remarkable new views of massive star-forming regions, revealing all stages in the life cycle of high-mass stars and their effects on their surroundings. We will tour several such regions, highlighting physical processes that characterize the life of a cluster of massive stars, from deeply-embedded cores too young to have established an HII region to superbubbles so large that they shape our views of galaxies. Along the way we see that X-ray observations reveal hundreds of pre-main sequence stars accompanying the massive stars that power great HII region complexes. The most massive stars themselves are often anomalously hard X-ray emitters; this may be a new indicator of close binarity. These complexes are sometimes suffused by diffuse X-ray structures, signatures of multi-million-degree plasmas created by fast O-star winds. In older regions we see the X-ray remains of the deaths of massive stars that stayed close to their birthplaces, exploding as cavity supernovae within the superbubbles that these clusters created.

  19. Gravity Binding and Pressure Bounding of HII Regions and Molecular Clouds in Interacting Galaxies

    NASA Astrophysics Data System (ADS)

    Beckman, John Etienne; Zaragoz-Cardiel, Javier; Font, Joan; Amram, Philippe; Camps-Fariña, Artemi

    2015-08-01

    We have observed a sample of 12 interacting galaxies using the Fabry-Perot interferometer GHαFaS (Galaxy Hα Fabry-Perot system) on the 4.2m William Herschel Telescope (WHT) at the Observatorio del Roque de los Muchachos, La Palma, deriving maps in Hα surface brightness, velocity and velocity dispersion. We extracted the physical parameters (Hα luminosities, velocity dispersions, and effective radii) of 1300 HII regions for the full sample with techniques for which velocity tagging is an essential step. We found two populations of HII regions, with a break at a gas mass of 106.5 solar masses. The mean density of the regions falls with radius for smaller masses, but rises with radius for larger masses. This is because in the lower mass range the HII regions are pressure bounded while in the upper range they are gravitationally bound. This analysis is underscored by using the turbulent velocity dispersion to show that the virial parameter for the regions shows values consistent with gravitational equilibrium in the upper range only. We were able to use ALMA observations of the molecular clouds in one of our objects, the Antennae galaxies, showing that for clouds with masses above 106.5 solar masses their densities increase with mass. The mass functions of the molecular clouds and HII regions in the Antennae show bimodal distributions, with the break at 106.5 solar masses clearly in evidence. We draw two conclusions of interest. Firstly the classical Larson scaling relation between surface density and mass does not operate in the upper mass range, implying higher star formation efficiency there. Secondly the similarity in the mass functions and density radius relations for the GMC’s and HII regions suggests that, at least in the upper mass range, the former remain gravitationally bound even after massive star formation has occurred.

  20. Density bounding in the HII regions of galactic discs: evidence and consequences

    NASA Astrophysics Data System (ADS)

    Beckman, J. E.; Rozas, M.; Zurita, A.; Cardwell, A.; Relaño, M.

    2000-11-01

    We present four lines of evidence leading to the conclusion that the HII regions in the discs of normal galaxies,notably the highly luminous regions,are density bounded: (1)The relation of central Hα surface brightness to total luminosity of a region departs from the predictions of uniformly ionization bounded systems (2)The geometry and intensity of the diffuse Hα from whole discs is well modeled if the Lyman continuum causing it leaks from the HIi regions (3) The Hα luminosity function of complete HII region populations shows a break whose parameters are explicable on the density bounding hypothesis and not on rival hypotheses,(4)The observed relation between the Hα velocity half-width and luminosity for HII regions is naturally accounted for via density bounding.A fractally clumpy cloud structure,and a straightforward law relating the mass of the most luminous star in a young cluster to the mass of its placental gas cloud give model parameters which can account for these observations.The parameters apply to conditions in galactic discs,and may well not apply directly to circumnuclear starbursts,but the fraction of ionizing photons which can escape from the whole galaxy can still be highly significant. We show how to quantify the fraction of the Lyman continuum escaping from leaky HII regions which finally escapes from the galactic discs,and can ionize large volumes of ultra-low density intra-cluster gas.We explore the possibility that this mechanism played a significant role during the reionization epoch of the early universe.

  1. Dust Content in Compact HII Regions (NGC 7538 -- IRS 1, IRS 2, and IRS 3)

    NASA Astrophysics Data System (ADS)

    Akabane, K.; Kuno, N.

    The luminosity of the central star in compact HII regions was estimated from the solid angle of the nearby IR sources subtended at the central star, to be 5 ˜ 10 times as intense as that of the IR sources. The luminosity gives the stellar UV photon rate, Nu(*)(s-1), under the assumption of a single star approximation. For gas of standard dust content, Nu(*) and the observed electron density, ne, provide the dust opacity of the ionizing photons, τSdn, along the optical path to the Strömgren sphere of radius rs. The ionizing photon opacity over the same optical path but with the actual dust content, τSdi, is also derived from Nu(*) and the observed emission measure, ne2(4 π/3)ri3, with ri of the radius of the ionized sphere. A relationship γNu(*)/(4 π ri2)1/2˜= 1.3 × 109 (s-1/2m-1) with γ= τSdi/ τSdn was obtained as an observational trend for the 4 compact HII regions of NGC7538(N). Fourteen selected compact HII regions from the data catalogued by VLA observations were examined for this trend, and a similar result was shown. A confined area within 1050 >= Nu (s-1, radio) >= 1044 and 15 >= γ >= 0.1 was proposed for the location of compact HII regions in their (ne - D) diagram.

  2. NH_3(1,1) survey toward southern hemisphere HII regions. I

    NASA Astrophysics Data System (ADS)

    Vilas-Boas, J. W. S.; Abraham, Z.

    2000-03-01

    The (J,K) = (1,1) metastable ammonia line was searched for in the direction of more than one hundred southern HII regions located between 270 degr and 15degr in galactic longitude, resulting in new detections toward 21 of them. Ammonia detection rate was about 30 % towards all directions except in the longitude interval 270degr -290degr where no ammonia lines were found in the 15 selected HII regions. A high detection rate (>= 0.6) was observed toward positions where IRAS point sources with color indices of ultra-compact HII regions were in the beam of the telescope. An anticorrelation between the number of detected NH_3 sources and the distance to the Galactic Center was found, compatible with the observed gradient in N abundance. From the value of this gradient and the detection rate of ammonia lines toward HII regions, it is inferred that the number of ammonia sources must be proportional to the inverse of the column density of the molecular cloud.

  3. Stellar-Nebular Feedback in Galaxian Starbursts: IR Spectral Imaging of HII Regions in M33

    NASA Astrophysics Data System (ADS)

    Waller, William; Boulanger, Francois; Brandl, Bernhard; Garnett, Donald; Gehrz, Robert; Gehrz and other GTO Team Members; Hodge, Paul; Humphreys, Roberta; Lee, Myung Gyoon; Murphy, Eric; Polomski, Elisha; Willner, Steven

    2004-09-01

    We propose a spectrophotometric investigation of starburst activity in the Local Group galaxy, Messier 33. By observing 7 selected giant HII regions that span a decade in metallicity, we will test the generic relationships between the ionizing stellar populations (previously observed with HST), the photo-dissociation regions (PDRs), and their associated dust content. We are especially interested in determining whether the observed variations in the stellar IMFs correlate with variations in the PDRs. We will use the IRS to obtain fully-sampled spectral maps of the 7 selected HII regions at 5.2 ==> 14.5 microns. The resulting datacubes will contain abundant spatial and spectral information on the molecular and dust content in the PDRs. This research program -- in close coordination with complementary GTO programs #5 and #63 -- will provide important benchmarks for interpreting starburst activity on many scales and over many epochs.

  4. VizieR Online Data Catalog: Line ratios in giant HII region H 1013 (Stasinska+, 2013)

    NASA Astrophysics Data System (ADS)

    Stasinska, G.; Morisset, C.; Simon-Diaz, S.; Bresolin, F.; Schaerer, D.; Brandl, B.

    2013-08-01

    Cedres & Cepa (2002, Cat. J/A+A/391/809) used CDD observations in several narrow-band filters to compile a catalogue of 338 HII regions in the inner parts of M 101 (NGC 5457), also providing information about their fluxes, extinctions, equivalent widths, spatial distribution, excitations, radiation hardness, ionization parameters and metallicities. H1013 is identified as the HII region number 299 in their catalogue. We use the Hα and Hβ continuum-subtracted images (kindly provided by B. Cedres) in our study. These images were obtained at the Nordic Optical Telescope with the ALFOSC instrument in direct imaging mode (spatial resolution of 0.189-arcsec/pix). (1 data file).

  5. A catalog of planetary nebula candidates and HII regions in NGC 3109

    NASA Astrophysics Data System (ADS)

    Peña, M.; Richer, M. G.; Stasińska, G.

    2007-04-01

    Aims:Images obtained with the ESO VLT and FORS1 in [O iii] 5007 on- and off-band, as well as rGunn filters, are analyzed to search for planetary nebula (PN) candidates. Methods: In the continuum-subtracted [O iii] 5007 on-band images, a large number of emission-line regions were detected. We describe the criteria employed for distinguishing PN candidates from compact HII regions. Results: The most unambiguous discriminators for the two classes of nebulae are the sizes and properties of the ionizing stars. Based upon these criteria, we have found 20 PN candidates for which we present coordinates, nebular [O iii] fluxes, and stellar magnitudes. The cumulative luminosity function for these PNe is discussed. A catalog of HII regions listing coordinates, nebular [O iii] fluxes, stellar magnitudes, and other characteristics is also presented. We find that HII regions are rather concentrated towards the disk of the galaxy, while PNe are distributed also above and below this structure, consistent with their belonging to an older stellar population. Based on observations collected at the European Southern Observatory, VLT, Paranal, Chile, program ID 076.B-0166.

  6. VizieR Online Data Catalog: Infrared emission of young HII regions (Cesaroni+, 2015)

    NASA Astrophysics Data System (ADS)

    Cesaroni, R.; Pestalozzi, M.; Beltran, M. T.; Hoare, M. G.; Molinari, S.; Olmi, L.; Smith, M. D.; Stringfellow, G. S.; Testi, L.; Thompson, M. A.

    2015-09-01

    Since the main scope of our study is to investigate the IR and radio properties of young massive stars, we have selected the sources classified as "ultracompact" and "compact" HII regions in the CORNISH catalogue. This a classification was obtained after visual inspection also using the Spitzer IRAC and MIPSGAL images (more details on the method are given in Purcell et al. 2013ApJS..205....1P, Cat. J/ApJS/205/1) (2 data files).

  7. Size of HII Regions Around High Redshift Quasars vs Intergalactic Medium Neutral Hydrogen Fraction at z~6

    NASA Astrophysics Data System (ADS)

    Maselli, A.; Gallerani, S.; Ferrara, A.; Choudury, T. S.

    2006-08-01

    We discuss the robustness of constraints on the intergalactic medium neutral hydrogen fraction inferred from the extent of HII regions of high redshift quasars by means of their absorption spectra. We have combined state-of-art SPH and 3D Radiative Transfer (RT) simulations to extract a sample of mock quasar spectra and we have analyzed such a sample with a procedure commonly adopted in real observations. Our analysis shows that the size of the quasar HII regions measured in quasar spectra strongly underestimate the real HII extent, as a result of absorption by residual neutral hydrogen inside the HII region and red damping wing absorption produced by HI just outside the HII region. We demonstrate that, even an idealized large sample of observed spectra -with negligible uncertainties on the quasars parameters (ie. lifetime, luminosity)- is compatible with a surrounding IGM whose mean IGM neutral hydrogen fraction can range freely in the interval [0.05,1] . We conclude, that our current knowledge of the re-ionization process is not accurate enough to allow a direct conversion of the quasars HII region extent into a value for the mean IGM ionization fraction. Finally, we propose a statistical method which could allow to extract such information from a large sample of quasar spectra at z>6.

  8. The Hydrodynamical Models of the Cometary Compact HII Region

    NASA Astrophysics Data System (ADS)

    Zhu, Feng-Yao; Zhu, Qing-Feng; Li, Juan; Zhang, Jiang-Shui; Wang, Jun-Zhi

    2015-10-01

    We have developed a full numerical method to study the gas dynamics of cometary ultracompact H ii regions, and associated photodissociation regions (PDRs). The bow-shock and champagne-flow models with a 40.9/21.9 M⊙ star are simulated. In the bow-shock models, the massive star is assumed to move through dense (n = 8000 cm-3) molecular material with a stellar velocity of 15 km s-1. In the champagne-flow models, an exponential distribution of density with a scale height of 0.2 pc is assumed. The profiles of the [Ne ii] 12.81 μm and H2 S(2) lines from the ionized regions and PDRs are compared for two sets of models. In champagne-flow models, emission lines from the ionized gas clearly show the effect of acceleration along the direction toward the tail due to the density gradient. The kinematics of the molecular gas inside the dense shell are mainly due to the expansion of the H ii region. However, in bow-shock models the ionized gas mainly moves in the same direction as the stellar motion. The kinematics of the molecular gas inside the dense shell simply reflects the motion of the dense shell with respect to the star. These differences can be used to distinguish two sets of models.

  9. Hydrodynamic Instability of Ionization Fronts in HII Regions

    SciTech Connect

    Mizuta, A; Kane, J; Ryutov, D; Remington, B; Takabe, H; Pound, M

    2003-08-21

    The authors investigate hydrodynamic instability of accelerating ionization fronts with two dimensional hydrodynamic simulations. When recombination in the ionized region is turned off, Rayleigh-Taylor instability is effective. Perturbation grows up with classical Rayleigh-Taylor growth rate. In the case with recombination, the local difference of absorption profile works to smooth the surface. The perturbation does not grow and the amplitude follows a damped oscillations with time.

  10. Formation of structures around HII regions: ionization feedback from massive stars

    NASA Astrophysics Data System (ADS)

    Tremblin, P.; Audit, E.; Minier, V.; Schmidt, W.; Schneider, N.

    2015-03-01

    We present a new model for the formation of dense clumps and pillars around HII regions based on shocks curvature at the interface between a HII region and a molecular cloud. UV radiation leads to the formation of an ionization front and of a shock ahead. The gas is compressed between them forming a dense shell at the interface. This shell may be curved due to initial interface or density modulation caused by the turbulence of the molecular cloud. Low curvature leads to instabilities in the shell that form dense clumps while sufficiently curved shells collapse on itself to form pillars. When turbulence is high compared to the ionized-gas pressure, bubbles of cold gas have sufficient kinetic energy to penetrate into the HII region and detach themselves from the parent cloud, forming cometary globules. Using computational simulations, we show that these new models are extremely efficient to form dense clumps and stable and growing elongated structures, pillars, in which star formation might occur (see Tremblin et al. 2012a). The inclusion of turbulence in the model shows its importance in the formation of cometary globules (see Tremblin et al. 2012b). Globally, the density enhancement in the simulations is of one or two orders of magnitude higher than the density enhancement of the classical ``collect and collapse`` scenario. The code used for the simulation is the HERACLES code, that comprises hydrodynamics with various equation of state, radiative transfer, gravity, cooling and heating. Our recent observations with Herschel (see Schneider et al. 2012a) and SOFIA (see Schneider et al. 2012b) and additional Spitzer data archives revealed many more of these structures in regions where OB stars have already formed such as the Rosette Nebula, Cygnus X, M16 and Vela, suggesting that the UV radiation from massive stars plays an important role in their formation. We present a first comparison between the simulations described above and recent observations of these regions.

  11. Infrared emission of young HII regions: a Herschel/Hi-GAL study

    NASA Astrophysics Data System (ADS)

    Cesaroni, R.; Pestalozzi, M.; Beltrán, M. T.; Hoare, M. G.; Molinari, S.; Olmi, L.; Smith, M. D.; Stringfellow, G. S.; Testi, L.; Thompson, M. A.

    2015-07-01

    Context. Investigating the relationship between radio and infrared emission of Hii regions may help shed light on the nature of the ionizing stars and the formation mechanism of early-type stars in general. Aims: We have taken advantage of recent unbiased surveys of the Galactic plane such as Herschel/Hi-GAL and VLA/CORNISH to study a bona fide sample of young Hii regions located in the Galactic longitude range 10°-65° by comparing the mid- and far-IR continuum emission to the radio free-free emission at 5 GHz. Methods: We have identified the Hi-GAL counterparts of 230 CORNISH Hii regions and reconstructed the spectral energy distributions of 204 of these by complementing the Hi-GAL fluxes with ancillary data at longer and shorter wavelengths. Using literature data, we obtained a kinematical distance estimate for 200 Hii regions with Hi-GAL counterparts and determined their luminosities by integrating the emission of the corresponding spectral energy distributions. We have also estimated the mass of the associated molecular clumps from the (sub)millimeter flux densities. Results: Our main finding is that for ~1/3 of the Hii regions the Lyman continuum luminosity appears to be greater than the value expected for a zero-age main-sequence star with the same bolometric luminosity. This result indicates that a considerable fraction of young, embedded early-type stars presents a "Lyman excess" possibly due to UV photons emitted from shocked material infalling onto the star itself and/or a circumstellar disk. Finally, by comparing the bolometric and Lyman continuum luminosities with the mass of the associated clump, we derive a star formation efficiency of 5%. Conclusions: The results obtained suggest that accretion may still be present during the early stages of the evolution of Hii regions, with important effects on the production of ionizing photons and thus on the circumstellar environment. More reliable numerical models describing the accretion process onto massive

  12. Toward unveiling internal properties of HII regions and their connections at the cosmic noon era

    NASA Astrophysics Data System (ADS)

    Shimakawa, Rhythm; Kodama, Tadayuki; Hayashi, Masao; Tadaki, Ken-ichi; Suzuki, Tomoko L.; Koyama, Yusei; Tanaka, Ichi; Yamamoto, Moegi

    2015-08-01

    The redshift interval z=2-3 is known as the cosmic noon that is the most active era of star formation across the Universe. In the past decade, many authors have investigated global properties of star-forming (SF) galaxies in this turbulent era, such as gas fractions and gaseous metallicities.With these achievements, we are going on to the next stage to understand the internal details of star formation at the cosmic noon era on the scale from entire galaxy into SF regions. Recent advent of near-infrared instruments typified by MOSFIRE on the Keck telescope, enable us with identifying the physical parameters of HII regions in ‘typical’ SF galaxies for the first time. Recent highlights suggest higher electron densities, higher ionization parameters, and harder UV radiation fields may be common.In this poster, based on the spectra of Hα selected SF galaxies at z=2.5 derived from MOSFIRE, we measure electron densities (ne) using the oxygen line ratio, and investigate the relationships between the electron density of ionized gas and other physical properties. As a result, we find that the specific star formation rate (sSFR) and the SFR surface density (ΣSFR) are correlated with the electron density. The ne-ΣSFR relation is likely to be linked to the star formation law in HII regions if we assume that hydrogen in HII regions is fully-ionized. However, we need some specific concerns that obtained physical parameters may depend on the scale dependence, since typical size of HII region is only <100 pc despite that we study physical states of entire galaxies. Thus we obtain surface-brightness-weighted and ensemble averaged line fluxes for the entire galaxy or the part that falls into the slit width.The thirty meter telescope (TMT) is a powerful instrument to resolve such a difficulty, since its spatial resolution reaches <100 pc on the physical scale at z~2 by AO assistance. This poster also presents what TMT can do for SF galaxies at z~2 with AO-assisted IFU

  13. VizieR Online Data Catalog: Galactic HII regions. I. Stellar distances (Foster+, 2015)

    NASA Astrophysics Data System (ADS)

    Foster, T.; Brunt, C. M.

    2016-04-01

    The cornerstone of our catalog of HII regions is the new systemic velocity measurements (with respect to the LSR), which come from high-resolution (1arcmin) λ21cm HI data and λ2.6mm 12CO (J=1-0) data. The HI data are entirely from the Canadian Galactic Plane Survey (CGPS; Taylor et al. 2003, cat. VI/128), whereas CO data are from either CGPS or the Exeter Five College Radio Astronomy Observatory (FCRAO) CO Galactic Plane Survey (described in Mottram & Brunt, 2010ASPC..438...98M; C. M. Brunt et al. 2013, in preparation), depending on longitude. Our catalog covers HII regions in the outer Galaxy only (R>R0) in the longitude range 90°{<=}l{<=}193° and mainly within a latitude of -3.5°{<=}b{<=}+5.5°. A high-latitude extension was also observed as part of the CGPS (99.85°{<=}l{<=}116.96°) up to b=+17.56°. The complete CGPS data set of 21cm line and continuum from 50.2°{<=}l{<=}193.3° and -3.55°{<=}b{<=}+5.55° are available at the Canadian Astronomy Data Centre (CADC; http://cadc.hia.nrc.ca/). 21cm HI line observations used herein were carried out with the seven-element interferometer and 26m radio telescopes at the Dominion Radio Astrophysical Observatory for the CGPS (Taylor et al. 2033, cat. VI/128). To trace molecular material in the second quadrant, we make use of the FCRAO Outer Galaxy Survey (OGS; Heyer et al., 1998ApJS..115..241H). We present our full catalog of 355 stars found in and around Galactic HII regions in Table1. Table2 in this paper gives the final heliocentric stellar distance to each of 103 nebulae in the outer Galaxy. (3 data files).

  14. HII regions in IC 1613: The ISM in a nearby dwarf irregular galaxy

    NASA Technical Reports Server (NTRS)

    Price, Jill S.; Mason, Stephen F.; Gullixson, Craig A.

    1990-01-01

    IC 1613, a nearby (725 kpc distant) dwarf irregular galaxy, has always been known to contain large, ring-shaped HII regions in its northeast corner. A new H alpha image has been obtained using the Bell Labs Charge Coupled Device (CCD) camera, an RCA 320 X 512 pixel-thinned, back-illuminated CCD, an H alpha filter of central wavelength 6562 A and width (full width half maximum) of 30 A, and the 42 inch telescope at Lowell Observatory. The low resolution images exhibit many new, faint features.

  15. Massive Stellar Content of Stellar Clusters in M 31's Giant HII Region Pellet 550

    NASA Astrophysics Data System (ADS)

    Brandner, W.; Bik, A.; Rochau, B.; Gennaro, M.; Kudryavtseva, N.; Stolte, A.; Hussmann, B.; Zinnecker, H.

    We report on the first set of LBT/LUCIFER near infrared observations of Pellet 550, one of the most massive star-forming regions in the disk of M 31. Compared to the Milky Way, M 31 offers a complete census of star-forming regions and starburst clusters, all located at virtually the same distance. The regions under study have been selected to include the most luminous HII regions as well as still partially embedded star-forming regions recently revealed by Spitzer. For the first time we are able to establish the massive stellar content, identify young, massive clusters, and study the nature of still partially embedded luminous infrared sources. The M 31 study is a first application of our previous studies to establish the properties of Milky Way starburst clusters as templates for extragalactic massive star-forming regions.

  16. Photoevaporation of Disks Around Young Stars: Application to Ultracompact HII Regions, Proplyds, and the Solar Nebula

    NASA Technical Reports Server (NTRS)

    Hollenbach, David; DeVincenzi, Donald L. (Technical Monitor)

    2001-01-01

    Young massive stars produce sufficient Lyman continuum photon luminosity to significantly affect the structure and evolution of the accretion disks surrounding them. A nearly static, ionized, isothermal 10' K atmosphere forms above the neutral disk, creating a photoevaporative flow from the outer parts of the disk. The resulting slow (10-50 km/s) ionized outflow, which persists for greater than or approximately 10(exp 5) years for disk masses M(sub d) to approximately 0.3M(sub *), may explain the observational characteristics of many ultracompact HII regions. We compare model results to the observed radio free-free spectra and luminosities of ultracompact HII regions and to the interesting source MWC349, which is observed to produce hydrogen masers. We also apply the results to the early solar nebula to explain the the dispersal of the solar nebula and the differences in hydrogen content in the giant planets. Finally, we model the small bright objects ("proplyds") observed in the Orion Nebula as disks around young, low mass stars which axe externally illuminated by the UV photons from the nearby massive star theta(sup 1)C.

  17. VizieR Online Data Catalog: HII Regions in NGC 4258 (Courtes+ 1993)

    NASA Astrophysics Data System (ADS)

    Courtes, G.; Petit, H.; Hua, C. T.; Martin, P.; Blecha, A.; Huguenin, D.; Golay, M.

    1995-07-01

    The distribution of ionized hydrogen in the spiral galaxy NGC 4258 is revisited using Hα images with both the Mont Megantic 160cm telescope equipped with a F/3 focal reducer and the Observatoire de Haute-Provence 120cm telescope at its newtonian F/6 focus in the direct imaging mode. The HII region distribution shows several well defined spiral structures as well as the very extended and peculiar "anomalous arms". The deprojection of these features is compared to the UV 2000A stellar arms obtained with the LAS- Geneva Observatory balloon-borne survey programme. The pitch angle of the N inner arm permits to detect the drift of the Hα spiral structures with respect to the evolved hot stellar population in the corresponding sector of the UV arm. This phenomenon seems to systematically appear in other galaxies. The conclusion should be that the origin of the drift is mainly kinematic and of evolutionary nature and provides perhaps the best method to evaluate the effect of the density waves. The anomalous arms have no apparent UV 2000A counterpart except perhaps in the inner region of the central stellar bulge. A comparison of the Hα morphology is made with the CO distribution and their radial velocity profiles that could renew the ballistic interpretation. A catalogue of 137 HII regions was compiled from the two sets of new CCD images, providing the X and Y off-set positions, along with the absolute flux and angular diameters corrected for observing conditions. The 1950 equatorial coordinates are given in the maps of our Hα observations. The derived power-law luminosity function is compared to those obtained for other galaxies. Comparing previous image-tube plates, taken between 1961 and 1969, to the recent CCD data for NGC 4258, we obtain flux estimates of the HII region hosting the supernova first discovered in radio frequencies on 1983. As a result, the integrated magnitude is in fair agreement with the report by Wild (IAU Circ 3803, 1983) of a 17th mag object in

  18. Extinction and PAH intensity variations across the HII region IRAS 12063-6259

    NASA Astrophysics Data System (ADS)

    Stock, D.; Peeters, E.; Tielens, X.; Otaguro, J.; Bik, A.

    The spatial variations in polycyclic aromatic hydrocarbon (PAH) band intensities are generally attributed to variations of the physical conditions in the environment hosting the emitting PAH molecules. However, in recent years, it has been suggested that such variations are caused mainly by extinction. To resolve this question, we have obtained near-infrared (NIR), mid-infrared (MIR) and radio observations of the compact HII region IRAS 12063-6259. We use these data to construct multiple independent extinction maps and to measure the main PAH feature intensities (6.2, 7.7, 8.6 and 11.2 µ m). Three extinction maps are derived: the first using the NIR hydrogen lines and case B recombination theory; the second combining the NIR data, radio data and case B recombination; and the third making use of the Spitzer/IRS MIR observations to measure the 9.8 µ m silicate absorption feature intensity using the Spoon method and PAHFIT. We conclude that different areas of IRAS 12063-6259 possess markedly different extinction properties, with some regions displaying both silicate absorption and corresponding NIR extinction, and other regions displaying NIR extinction and no corresponding silicate absorption. While such breakdowns of the relationship between the NIR extinction and the silicate absorption strength have been observed in molecular clouds, they have never been observed for HII regions. We then compare the PAH intensity variations in the Spitzer/IRS data after dereddening to those found in the original data. Generally it was found that the PAH band intensity variations persist even after dereddening, implying that extinction is not the main cause of the PAH band intensity variations.

  19. Anomalous Microwave Emission in HII regions: is it really anomalous ? The case of RCW 49

    NASA Astrophysics Data System (ADS)

    Paladini, Roberta; Ingallinera, Adriano; Agliozzo, Claudia; Tibbs, Christopher; Noriega-Crespo, Alberto; Umana, Grazia; Dickinson, Clive; Trigiglio, Corrado

    2016-01-01

    The detection of an excess of emission at microwave frequencies with respect to the predicted free-free emission has been reportedfor several Galactic HII regions. Here, we investigate the case of RCW 49, for which the Cosmic Background Imager tentatively (~ 3 sigma) detected Anomalous Microwave Emission at 31 GHz on angular scales of 7'. Using the Australia Telescope Compact Array, we carried out a multi-frequency (5 GHz, 19 GHz and 34 GHz) continuum study of the region, complemented by observations of the H109 alpha radio recombination line. The analysis shows that: 1) the spatial correlation between the microwave and IR emission persists on angular scales from 3.4' to 0.4'', although the degree of the correlation slightly decreases at higher frequencies and on smaller angular scales; 2) the spectral indices between 1.4 and 5 GHz are globally in agreement with optically thin free-free emission, however, ~ 30 % of these are positive and much greater than -0.1, consistently with a stellar wind scenario; 3) no major evidence for inverted free-free radiation is found, indicating that this is likely not the cause of the Anomalous Emission in RCW 49. Although our results cannot rule out the spinning dust hypothesis to explain the tentative detection of Anomalous Microwave emission in RCW 49, they emphasize the complexity of astronomical sources very well known and studied such as HII regions, and suggest that, at least in these objects, the reported excess of emissionmight be ascribed to alternative mechanisms such as stellar winds and shocks.

  20. Radiation-MHD Simulations of Pillars and Globules in HII Regions

    NASA Astrophysics Data System (ADS)

    Mackey, J.

    2012-07-01

    Implicit and explicit raytracing-photoionisation algorithms have been implemented in the author's radiation-magnetohydrodynamics code. The algorithms are described briefly and their efficiency and parallel scaling are investigated. The implicit algorithm is more efficient for calculations where ionisation fronts have very supersonic velocities, and the explicit algorithm is favoured in the opposite limit because of its better parallel scaling. The implicit method is used to investigate the effects of initially uniform magnetic fields on the formation and evolution of dense pillars and cometary globules at the boundaries of HII regions. It is shown that for weak and medium field strengths an initially perpendicular field is swept into alignment with the pillar during its dynamical evolution, matching magnetic field observations of the ‘Pillars of Creation’ in M16. A strong perpendicular magnetic field remains in its initial configuration and also confines the photoevaporation flow into a bar-shaped, dense, ionised ribbon which partially shields the ionisation front.

  1. Molecular Cores in Different Evolutionary Stages near Luminous IRAS Sources and UC HII Regions

    NASA Astrophysics Data System (ADS)

    Zhu, Lei; Wu, Yue-Fang

    2007-06-01

    We report the results of 12CO and 13CO J=1 0 observations of eight candidates of Ultra-Compact (UC) HII regions with the Purple Mountain Observatory (PMO) Qinghai 13.7 -m telescope, which resulted in revealing 11 molecular cores. Their masses range from 130 to 1.7×104 Modot, with different spatial scales (1~ 6 pc). Also presented are the relevant HCO+ J=1 0 maps, which enabled us to investigate more detailed structures of these cores. Further comparisons show that four of the cores deviated from the centers of infrared (MIR) emission of Midcourse Space Experiment (MSX), while others correspond either to bright MIR sources or diffuse MIR background. This indicates various evolutionary phases of the cores, including quite early ones for those without MIR sources.

  2. The Violent Interstellar Medium in the Giant HII Region 30 Doradus

    NASA Astrophysics Data System (ADS)

    Chu, Y.-H.; Grebel, E. K.; Bomans, D. J.; Smith, R. C.; Yang, H.

    1996-08-01

    The giant HII region 30 Doradus shows prominent filaments of ionized gas, bright diffuse X-ray emission, and violent internal gas motions. These features indicate the prevalence of interstellar shocks produced by fast stellar winds and supernova blasts. 30 Dor contains two clusters: the populous young cluster R 136 and the older cluster Hodge 301. The R 136 cluster, being only 3-4 million years old, should still have all its massive stars. Its most massive stars would be interacting with the ambient interstellar medium via copious stellar winds. The Hodge 301 cluster, being nearly 20 million years old, has lost its most massive stars. The remaining stars are not powerful sources of stellar winds, so the cluster has been interacting with the ambient medium mostly through occasional supernova blasts. The interstellar gas around these two clusters offers a unique opportunity for us to study a wind-dominated interaction and a supernova-dominated interaction in a giant HII region. We have obtained proprietary and archival HST WFPC2 images, ROSAT X-ray observations, and high-resolution echelle spectra of 30 Dor in the vicinity of R 136 as well as Hodge 301. These data are used to map the distribution of high velocity gas and to determine the origin of interstellar shocks. We show that the kinematic signatures of wind-dominated shocks and supernova remnant shocks are distinctly different. The most violent motion in 30 Dor is associated with the older cluster Hodge 301. Clearly, star formation in 30 Dor is not coeval; while the younger cluster is responsible for the ionization of the interstellar gas, the older cluster is responsible for the violent interstellar motion. If 30 Dor represents a miniature but typical starburst situation, these results must be taken into account when studying distant, unresolved starburst phenomena.

  3. Helium Ionization in the Diffuse Ionized Gas surrounding Ultra-compact HII regions

    NASA Astrophysics Data System (ADS)

    Anish Roshi, D.; Churchwell, Edward B.

    2016-01-01

    We observed radio recombination lines (RRLs) from regions surrounding three Ultra-compact HII (UCHII) regions at frequencies near 5 GHz. The observations were made with the Green Bank Telescope (GBT). From existing observations we know that helium in the diffuse ionized gas (DIR), located far from the ionizing source, is not fully ionized. The objectives of our observations are to determine (a) the distance from the ionizing stars where helium is under ionized for a variety of physical conditions and (b) whether the helium ionization depends on the age of the ionizing star. With these objectives, we observed RRLs towards 16 positions in the envelops of UCHII regions G10.15-0.34, G23.46-0.20 and G29.96-0.02. Helium lines were detected toward 10 of the observed positions and hydrogen RRLs were detected toward all the observed positions. The observed ratio of ionized helium to ionized hydrogen (He^+/H^+) at the positions where helium lines are detected range between 0.03 and 0.09. At positions where helium lines are not detected the upper limit on the ratio is ~ 0.05. We discuss the dependence of He^+/H^+ ratio on the distance from and age of the ionizing star clusters in the observed sources.

  4. Formation of Pillars at the Boundaries between HII Regions and Molecular Clouds

    SciTech Connect

    Mizuta, A; Kane, J O; Pound, M W; Remington, B A; Ryutov, D D; Takabe, H

    2006-04-20

    We investigate numerically the hydrodynamic instability of an ionization front (IF) accelerating into a molecular cloud, with imposed initial perturbations of different amplitudes. When the initial amplitude is small, the imposed perturbation is completely stabilized and does not grow. When the initial perturbation amplitude is large enough, roughly the ratio of the initial amplitude to wavelength is greater than 0.02, portions of the IF temporarily separate from the molecular cloud surface, locally decreasing the ablation pressure. This causes the appearance of a large, warm HI region and triggers nonlinear dynamics of the IF. The local difference of the ablation pressure and acceleration enhances the appearance and growth of a multimode perturbation. The stabilization usually seen at the IF in the linear regimes does not work due to the mismatch of the modes of the perturbations at the cloud surface and in density in HII region above the cloud surface. Molecular pillars are observed in the late stages of the large amplitude perturbation case. The velocity gradient in the pillars is in reasonably good agreement with that observed in the Eagle Nebula. The initial perturbation is imposed in three different ways: in density, in incident photon number flux, and in the surface shape. All cases show both stabilization for a small initial perturbation and large growth of the second harmonic by increasing amplitude of the initial perturbation above a critical value.

  5. ISO Mid-Infrared Observations of Giant HII Regions in M33

    NASA Technical Reports Server (NTRS)

    Skelton, B. P.; Waller, W. H.; Hodge, P. W.; Boulanger, F.; Cornett, R. H.; Fanelli, M. N.; Lequeux, J.; Stecher, T. P.; Viallefond, F.; Hui, Y.

    1999-01-01

    We present Infrared Space Observatory Camera (ISOCAM) Circular Variable Filter scans of three giant HII regions in M33. IC 133, NGC 595, and CC 93 span a wide range of metallicity, luminosity, nebular excitation, and infrared excess; three other emission regions (CC 43, CC 99, and a region to the northeast of the core of NGC 595) are luminous enough in the mid-infrared to be detected in the observed fields. ISOCAM CVF observations provide spatially resolved observations (5'') of 151 wavelengths between 5.1 and 16.5 microns with a spectral resolution R = 35 to 50. We observe atomic emission lines ([Ne II], [Ne III], and [S IV]), several "unidentified infrared bands" (UIBs; 6.2, 7.7, 8.6, 11.3, 12.0, and 12.7 microns), and in some cases a continuum which rises steeply at longer wavelengths. We conclude that the spectra of these three GHRs are well explained by combinations of ionized gas, PAHs, and very small grains in various proportions and with different spatial distributions. Comparisons between observed ratios of the various UIBs with model ratios indicate that the PAHs in all three of the GHRs are dehydrogenated and that the small PAHs have been destroyed in IC 133 but have survived in NGC 595 and CC 93. The [Ne III]/[Ne II] ratios observed in IC 133 and NGC 595 are consistent with their ages of 5 and 4.5 Myr, respectively; the deduced ionization parameter is higher in IC 133, consistent with its more compact region of emission.

  6. Massive Star Formation in NGC4038/4039: HII Regions and Supernova Remnants in "The Antennae"

    NASA Technical Reports Server (NTRS)

    Neff, S. G.; Ulvestad, J. S.; Fisher, Richard (Technical Monitor)

    2000-01-01

    The nearest merger, NGC4038/4039 ("The Antennae, Arp244), is undergoing a starburst apparently triggered and driven by the ongoing interaction. The system provides an excellent laboratory to study star formation processes because well-studied and nearby (21 Mpc assumed here). Models of the interaction suggest that the interaction's first periapse occurred 200 Myr ago, and that final coalescence will occur in another 100 Myr. Blue and H alpha images show a continuous loop of bright knots around the NGC4038 (northern) nucleus, continuing down through the NGC4039 (southern) nucleus. Recent HST V and I images resolve the star-forming knots into several thousand blue compact clusters, with ages 5Myr for the youngest clusters. Far Ultraviolet (lambda 1500A) observations directly detect O and B stars in regions of low extinction; the total mass of young stars so observed is approximately 8 x 10 (exp 5) solar mass. FIR observations imply a star formation rate of approximately 5 M (sub 0) dot yr (sup -1) or greater. We used the VLA at 6 and 4 cm to obtain high resolution radio images of the star-formation regions in NGC4038/4038. We used high resolution imaging to identify compact radio emitting regions and spectral indices of the compact regions to differentiate between thermal sources such as HII regions (flat spectra) and supernova, remnants (steep spectra). We found that compact radio sources produce approximately 12% and/sim 25 strongest radio emission occurs between the galaxies, at an optically unremarkable location near but not coincident with an extremely red cluster. The radio peak is at a location of intense star formation (as detected in the mid-IR, reference?) and of dense molecular gas. We identify 115 individual compact 6cm radio sources and 63 individual 4 cm sources in the system, to a limiting luminosity of approximately 2 x 10 (exp 1) 8 W Hz (sup -1) (or /sim4x the luminosity of Cas A). Of the strongest sources, for which the h flux densities are large

  7. Photoevaporating Disks around Young Stars: Ultracompact HII Regions and Protoplanetary Disks.

    NASA Astrophysics Data System (ADS)

    Johnstone, Douglas Ian

    1995-01-01

    Newly formed stars produce sufficient Lyman continuum luminosity phi to significantly alter the structure and evolution of the accretion disk surrounding them. In the absence of a stellar wind, a nearly static, photoionized, 10^4 K, disk atmosphere, with a scale height that increases with disk radius varpi as varpi^{3/2 }, forms inside the gravitational radius varpig ~ 1014(M_*/ M_odot) cm where M _* is the mass of the central star. This ionized atmosphere is maintained by both the direct radiation from the central star and the diffuse field produced in the disk atmosphere by the significant fraction of hydrogen recombinations directly to the ground state. Beyond varpig the material evaporated from the disk is capable of escaping from the system and produces an ionized disk wind. The mass-loss due to this disk wind peaks at varpig . The inclusion of a stellar wind into the basic picture reduces the height of the inner disk atmosphere and introduces a new scale radius varpi_ {w} where the thermal pressure of the material evaporated from the disk balances the ram pressure in the wind. In this case the mass-loss due to the disk wind peaks at varpiw and is enhanced over the no-wind case. The photoevaporation of disks around newly formed stars has significance to both ultracompact HII regions and the dispersal of solar-type nebulae. High mass stars are intrinsically hot and thus yield sufficient Lyman luminosity to create, even without a stellar wind, disk mass-loss rates of order 2 times 10 ^{-5}phi_sp{49} {1/2} M_odotyr ^{-1}, where phi 49 = phi/(10 49 Lyman continuum photons s^{-1}). This wind, which will last until the disk is dispersed, ~ 10^5 yrs if the disk mass is M_ {d}~0.3M_*, yields sizes, emission measures and ages consistent with observations of ultracompact HII regions. The well-observed high mass star MWC 349 may be the best example to date of an evaporating disk around a high mass star. On the other end of the stellar scale, many newly formed low

  8. The Carina Nebula and Gum 31 molecular complex - I. Molecular gas distribution, column densities, and dust temperatures

    NASA Astrophysics Data System (ADS)

    Rebolledo, David; Burton, Michael; Green, Anne; Braiding, Catherine; Molinari, Sergio; Wong, Graeme; Blackwell, Rebecca; Elia, Davide; Schisano, Eugenio

    2016-03-01

    We report high-resolution observations of the 12CO(1-0) and 13CO(1-0) molecular lines in the Carina Nebula and the Gum 31 region obtained with the 22-m Mopra telescope as part of The Mopra Southern Galactic Plane CO Survey. We cover 8 deg2 from l = 285° to 290°, and from b = -1.5° to +0.5°. The molecular gas column density distributions from both tracers have a similar range of values. By fitting a grey-body function to the observed infrared spectral energy distribution from Herschel maps, we derive gas column densities and dust temperatures. The gas column density has values in the range from 6.3 × 1020 to 1.4 × 1023 cm-2, while the dust temperature has values in the range from 17 to 43 K. The gas column density derived from the dust emission is approximately described by a lognormal function for a limited range of column densities. A high-column-density tail is clearly evident for the gas column density distribution, which appears to be a common feature in regions with active star formation. There are regional variations in the fraction of the mass recovered by the CO emission lines with respect to the total mass traced by the dust emission. These variations may be related to changes in the radiation field strength, variation of the atomic to molecular gas fraction across the observed region, differences in the CO molecule abundance with respect to H2, and evolutionary stage differences of the molecular clouds that compose the Carina Nebula-Gum 31 complex.

  9. SOAR-OSIRIS observations of the Sh 2-307 HII region: triggered star formation beyond the Solar Circle

    NASA Astrophysics Data System (ADS)

    Roman-Lopes, A.

    2009-09-01

    This work aims to study the Sh 2-307 HII region and related stellar population. Near-infrared imaging and spectroscopic observations in the direction of Sh 2-307 were performed using the Ohio State InfraRed Imager/Spectrometer (OSIRIS) at the Southern Observatory for Astrophysical Research (SOAR) Telescope. The photometric data were analysed from colour-colour and colour-magnitude diagrams, while the spectroscopic results were interpreted from the comparison of the science spectra with those obtained from known OB stars. From J-, H- and K-band spectra of the brightest source in the cluster, we conclude that it has a near-infrared spectrum compatible with those of O9V-O9.5V stars. Using the derived spectral type and the respective J-, H- and K-band photometry, we compute a heliocentric distance of 3.2 +/- 0.5kpc, which, for R0 = 8kpc, puts this cluster at more than 10kpc from the Galactic Centre. From the Brγ, H2 and continuum narrow-band images we were able to detect both the near-infrared (NIR) counterpart of the associated HII region and the interface between the ionized and cool molecular gas. Using the 5-GHz continuum flux density taken from the Parkes-MIT-NRAO (PMN) catalogue and the Brγ narrow-band image, we estimate that the HII region has a mean diameter of 0.94 +/- 0.15pc, mean electron density of 550cm-3 and a dynamical age of 1.6 × 106yr. The large fraction of sources presenting excess emission at 2μm suggests that the stellar population is very young, with many sources still in the pre-main-sequence accreting phase. By the use of theoretical pre-main-sequence tracks we derived a cluster mean age of about 2.5Myr, and from the analyses of the fraction of excess emission sources as a function of their spatial distribution we found evidence for an age spread for the embedded pre-main-sequence stellar population. Finally, from the study of the spatial distribution of the low-mass sources relative to the main cluster source and associated

  10. HII Galaxies in 3D

    NASA Astrophysics Data System (ADS)

    Telles, E.

    2016-06-01

    In this contribution I review some results of the integral field spectroscopy of HII galaxies. The two main topics are related to their internal kinematics and the distribution of physical conditions. HII galaxies present a L-σ relation similar to elliptical galaxies. However, the origin of supersonic motions of the ionized gas (σ) is still a matter of debate. We show that the core of the star forming region dominates the internal kinematics and probes the underlying turbulent motions. The show our latest calibration of the L-sigma relation of local HII galaxies. We also show that the physical conditions are very uniform throughout the whole extent of the star forming region, once you account for the levels of ionization. HII galaxies are excellent laboratories for constraining the ionization power of high mass stars at low metallicities.

  11. VizieR Online Data Catalog: A CS(2-1) survey of UC HII regions (Bronfman+, 1996)

    NASA Astrophysics Data System (ADS)

    Bronfman, L.; Nyman, L.-A.; May, J.

    1995-09-01

    We have made a complete survey of the CS(2-1) emission toward IRAS point sources in the galactic plane. The sources observed were selected according to their far infrared (FIR) colors, which are characteristic of UC HII regions. They have 25μm/12μm flux ratios larger than 3.7 and 60μm/12μm flux ratios larger than 19.3. The survey covered a region from b=-2deg to b=2deg from l=300deg to l=0deg and from l=0deg to l=60deg, and from b=-4deg to b=4deg elsewhere. We detected 843 sources out of 1427 sources observed. The distributions of detected and undetected sources in a FIR color-color diagram show some differences, suggesting that more than one type of object is present in our observed sample. (1 data file).

  12. Observations of HII regions at millimeter wavelengths with the O.A.S.I. telescope at Terra Nova Bay

    NASA Astrophysics Data System (ADS)

    Sabbatini, L.; Dall'Oglio, G.; Davies, R. D.; Cavaliere, F.; Martinis, L.; Miriametro, A.; Pizzo, L.; Russo, P. A.; Valenziano, L.

    We report on our latest investigations into strong HII regions lying on the Galactic plane. They are sources of free-free emission in radio and dust emission in IR, but they have not been observed in the millimeter range until now. Our efforts to understand their behaviour in this range will be displayed. These observations were carried out with the O.A.S.I. telescope at Terra Nova Bay from November to December 2001. The receiving system consisted of a bolometric detector operating at wavelengths of 1.25 and 2 millimeter, with a resolution of 5 arcmin. We will briefly describe the observational techniques and the preliminary results for two of these sources, G291.6 -0.5 and G291.3 -0.7; we will also discuss some improvements to be introduced for further observations.

  13. Chandra X-ray observations of the HII region G5.89-0.39 and TeV Source HESSJ1800-240B

    NASA Astrophysics Data System (ADS)

    Rowell, G.; Horns, D.; Uchiyama, Y.; Funk, S.; Wagner, S.; Nicholas, B.; H.E.S.S. Collaboration

    The TeV gamma-ray sources in the field of the old age (> 10000 yr) supernova remnant (SNR) W28 present a unique opportunity to probe for a new type of multi-TeV particle accelerator, namely, HII regions. One such example is the TeV source HESS J1800-240B which is found towards the highly unusual HII region complex G5.89-0.39. In this context X-rays studies are highly valuable in probing the particle acceleration potential of such HII regions and their subsequent contribution to the gamma-ray emission. Previous high resolution XMM-Newton X-ray observations despite being affected by stray light from a nearby X-ray binary, revealed several sources co-located with the two star forming components of G5.89-0.39, namely G5.89-0.39A, a HII region, as well as G5.89-0.39B, an ultracompact or UCHII region. Here we describe preliminary analysis and results from our Chandra observations towards G5.89-0.39 and HESS J1800-240B (∼80 ks) which are not affected by stray light. With Chandra, we reveal over 200 X-ray sources which appear to cluster somewhat towards G5.89-0.39A and B respectively. This includes possibly extended emission towards a massive O5 or earlier spectral type star (known as Feldt's star) thought to provide much of the ionisation and energetics in G5.89-0.39B. Some of the X-ray sources exhibit energetics typical of young moderate to high mass stars. Our Chandra observations reveal for the first time the extent of star formation in the two HII components. Ongoing work centres on detailed spectral studies, cross-correlation with stellar catalogues, and the search for extended X-ray emission.

  14. Circumstantial Starbirth in Starbursts: Systematic Variations in the Stellar and Nebular Content of Giant HII Regions in the Local Group Galaxy M33

    NASA Astrophysics Data System (ADS)

    Waller, W. H.; Murphy, E. J.; Gherz, R. D.; Polomski, E.; Woodward, C. E.; Fazio, G. G.; Rieke, G. H.; Spitzer/M33 Research Team

    2005-12-01

    From the Orion Nebula to the Hubble Deep Field, starburst activity can be seen transforming galaxian clouds of gas into populous clusters of stars. The pyrotechnics and chemical enrichment associated with this activity have led to outcomes as ubiquitous as interstellar dust and as exquisite as life on Earth. In this talk, I will focus on the circumstances of star formation in the environmental context of ongoing starburst activity. I begin with the premises that (1) the formation of a single star takes time, (2) the formation of a populous cluster takes even more time, and (3) ''stuff'' happens in the interim. Hubble images of the Orion Nebula and Eagle Nebula show how hot stars can excavate neighboring clouds of gas and photoevaporate the star-forming cores that are exposed. Hubble observations of giant HII regions in M33 reveal a significant variation in the stellar populations, such that the most metal-rich HII regions contain the greatest proportions of the most massive stars. ISO and Spitzer observations of these same HII regions reveal corresponding variations in the nebular content. These multi-wavelength diagnostics of the stellar-nebular feedback in galaxian starbursts suggest a star-forming mechanism which is subject to photo-evaporative ablation -- an erosive process that is systematically mediated by the metal abundance and corresponding amounts of protective dust in the starbursting environment.

  15. The effect of massive stars on the ionized medium of extragalactic HII regions

    NASA Technical Reports Server (NTRS)

    Castaneda, Hector O.

    1993-01-01

    Giant extragalactic H2 regions (GEHR) are centers of active star formation, ionized by populous clusters of OB stars. These objects are characterized by their low electron density, linear dimensions of order of 10(exp 2) - 10(exp 3) pc, varied morphology, and inhomogeneous distribution of the gas. They are ideal laboratories to study the processes of interaction between the gas and the stars, that could then be extended to the study of H2 and starburst galaxies. An observational program on a selected group of giant H2 regions with the use of one- and two-dimensional spectroscopy is being conducted. Our aim is two-fold: to understand the internal structure of the regions and to study the kinematics and dynamics of the ionized gas. A short report of our ongoing research is presented.

  16. VizieR Online Data Catalog: HIPASS-ZoA HII regions (Alves+, 2015)

    NASA Astrophysics Data System (ADS)

    Alves, M. I. R.; Calabretta, M.; Davies, R. D.; Dickinson, C.; Staveley-Smith, L.; Davis, R. J.; Chen, T.; Barr, A.

    2015-11-01

    The results presented in this paper use a combination of the HIPASS (Staveley-Smith, 1996PASA...13..187S) and ZOA (Staveley-Smith et al., 1998AJ....116.2717S) data sets for the Galactic plane region l=196°-0°-52° and |b|<=5°. (1 data file).

  17. Populations of High-Luminosity Density-Bounded HII Regions in Spiral Galaxies? Evidence and Implications

    NASA Technical Reports Server (NTRS)

    Beckman, J. E.; Rozas, M.; Zurita, A.; Watson, R. A.; Knapen, J. H.

    2000-01-01

    In this paper we present evidence that the H II regions of high luminosity in disk galaxies may be density bounded, so that a significant fraction of the ionizing photons emitted by their exciting OB stars escape from the regions. The key piece of evidence is the presence, in the Ha luminosity functions (LFs) of the populations of H iI regions, of glitches, local sharp peaks at an apparently invariant luminosity, defined as the Stromgren luminosity Lstr), LH(sub alpha) = Lstr = 10(sup 38.6) (+/- 10(sup 0.1)) erg/ s (no other peaks are found in any of the LFs) accompanying a steepening of slope for LH(sub alpha) greater than Lstr This behavior is readily explicable via a physical model whose basic premises are: (a) the transition at LH(sub alpha) = Lstr marks a change from essentially ionization bounding at low luminosities to density bounding at higher values, (b) for this to occur the law relating stellar mass in massive star-forming clouds to the mass of the placental cloud must be such that the ionizing photon flux produced within the cloud is a function which rises more steeply than the mass of the cloud. Supporting evidence for the hypothesis of this transition is also presented: measurements of the central surface brightnesses of H II regions for LH(sub alpha) less than Lstr are proportional to L(sup 1/3, sub H(sub alpha)), expected for ionization bounding, but show a sharp trend to a steeper dependence for LH(sub alpha) greater than Lstr, and the observed relation between the internal turbulence velocity parameter, sigma, and the luminosity, L, at high luminosities, can be well explained if these regions are density bounded. If confirmed, the density-bounding hypothesis would have a number of interesting implications. It would imply that the density-bounded regions were the main sources of the photons which ionize the diffuse gas in disk galaxies. Our estimates, based on the hypothesis, indicate that these regions emit sufficient Lyman continuum not only to

  18. ASTE observations in the 345 GHz window towards the HII region N113 of the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Paron, S.; Ortega, M. E.; Cunningham, M.; Jones, P. A.; Rubio, M.; Fariña, C.; Komugi, S.

    2014-12-01

    Aims: The HII region N113 is located in the central part of the Large Magellanic Cloud (LMC) with an associated molecular cloud that is very rich in molecular species. Most of the previously observed molecular lines cover the frequency range 85-270 GHz. Thus, a survey and study of lines at the 345 GHz window is required for a more complete understanding of the chemistry and excitation conditions of this region. Methods: We mapped a region of 2.´5 × 2.´5 centred at N113 using the Atacama Submillimeter Telescope Experiment in the 13CO J = 3-2 line with an angular and spectral resolution of 22'' and 0.11 km s-1. In addition, we observed 16 molecular lines as single pointings towards its centre. Results: From the 13CO J = 3-2 map we estimate the local thermodynamic equilibrium (LTE) and virial masses in about 1 × 104 and 4.5 × 104M⊙ for the molecular cloud associated with N113. From the dust continuum emission at 500 μm we additionally obtain a mass of gas of 7 × 103M⊙. Towards the cloud centre we detected emission from 12CO, 13CO, C18O (3-2), HCN, HNC, HCO+, C2H (4-3), and CS (7-6); these are the first reported detections of the HCN, HNC, and C2H (4-3) lines from this region. We confirm the detection of CS (7-6), which was previously tentatively detected. From analysing the HCN, HNC, and C2H lines we suggest that they might be emitted from a photodissociation region (PDR). Moreover, we suggest that the chemistry involving the C2H lines in N113 is probably similar to that in Galactic PDRs. We analysed the HCN J = 4-3, J = 3-2, and J = 1-0 lines with the code RADEX and we conclude that we observe very high density gas, between some 105 and 107 cm-3.

  19. VizieR Online Data Catalog: Radio observations of Galactic WISE HII regions (Anderson+, 2015)

    NASA Astrophysics Data System (ADS)

    Anderson, L. D.; Armentrout, W. P.; Johnstone, B. M.; Bania, T. M.; Balser, D. S.; Wenger, T. V.; Cunningham, V.

    2016-01-01

    We draw our targets from the MIR objects in the WISE catalog of Anderson+, 2014, J/ApJS/212/1. We also include in our sample Sharpless H II regions (Sharpless 1959, VII/20). See section 2 for further details. Our observations were made with the GBT 100m telescope from 2012 July through 2014 August. There are seven radio recombination lines (RRLs) that can be cleanly observed simultaneously with the GBT in the X-band: H87α to H93α. We average these seven RRLs (each at two orthogonal polarizations) to create a single average RRL spectrum. We followed the same GBT observational procedure as in the original HRDS (Green Bank Telescope H II Region Discovery Survey (GBT HRDS; Bania et al. 2010ApJ...718L.106B). (3 data files).

  20. Outflow-confined HII Regions. I. First Signposts of Massive Star Formation

    NASA Astrophysics Data System (ADS)

    Tanaka, Kei E. I.; Tan, Jonathan C.; Zhang, Yichen

    2016-02-01

    We present an evolutionary sequence of models of the photoionized disk-wind outflow around forming massive stars based on the Core Accretion model. The outflow is expected to be the first structure to be ionized by the protostar and can confine the expansion of the H ii region, especially in lateral directions in the plane of the accretion disk. The ionizing luminosity increases as Kelvin-Helmholz contraction proceeds, and the H ii region is formed when the stellar mass reaches ˜10-20{M}⊙ depending on the initial cloud core properties. Although some part of the outer disk surface remains neutral due to shielding by the inner disk and the disk wind, almost the whole of the outflow is ionized in 103-{10}4 {{y}}{{r}} after initial H ii region formation. Having calculated the extent and temperature structure of the H ii region within the immediate protostellar environment, we then make predictions for the strength of its free-free continuum and recombination line emission. The free-free radio emission from the ionized outflow has a flux density of ˜(20-200) × \\quad {(ν /10{{GHz}})}p {{mJy}} for a source at a distance of 1 kpc with a spectral index p ≃ 0.4-0.7, and the apparent size is typically ˜500 AU at 10 GHz. The {{H}}40α line profile has a width of about 100 {km} {{{s}}}-1. These properties of our model are consistent with observed radio winds and jets around forming massive protostars.

  1. The stellar content and formation history of the Giant HII region W51 using IRMOS

    NASA Astrophysics Data System (ADS)

    Davies, Ben; MacKenty, John; Clark, Simon; Figer, Don

    2007-08-01

    The W51 Giant Molecular Cloud is amongst the most massive within the Galaxy, and harbours widespread and significant massive star formation (SF). However this activity appears qualitatively different from the spatially segregated, sequentially triggered SF occuring in e.g. the G305 and the 30 Dor star forming regions, apparently being quasi- simultaneous and multi-seeded. We propose to obtain near-IR spectroscopy of selected regions within W51 to complement planned deep imaging observations, in order to (i) determine if SF at these sites is proceeding independently or instead is triggered by older, adjacent activity and (ii) to investigate the claims of Okumura et al. (2000) for a top heavy IMF and hence to investigate if the IMF shows an environmental dependence. Finally, a measurement of the total stellar mass in W51 will enable the SF efficiency to be determined and compared to other star forming regions, to investigate potential dependencies on environment or the mode of SF, e.g triggered or multi-seeded.

  2. Anomalous Microwave Emission in HII Regions: Is it Really Anomalous? The Case of RCW 49

    NASA Astrophysics Data System (ADS)

    Paladini, Roberta; Ingallinera, Adriano; Agliozzo, Claudia; Tibbs, Christopher T.; Noriega-Crespo, Alberto; Umana, Grazia; Dickinson, Clive; Trigilio, Corrado

    2015-11-01

    The detection of an excess of emission at microwave frequencies with respect to the predicted free-free emission has been reported for several Galactic H ii regions. Here, we investigate the case of RCW 49, for which the Cosmic Background Imager tentatively (˜3σ) detected Anomalous Microwave Emission (AME) at 31 GHz on angular scales of 7‧. Using the Australia Telescope Compact Array, we carried out a multi-frequency (5, 19, and 34 GHz) continuum study of the region, complemented by observations of the H109α radio recombination line. The analysis shows that: (1) the spatial correlation between the microwave and IR emission persists on angular scales from 3.‧4 to 0.″4, although the degree of the correlation slightly decreases at higher frequencies and on smaller angular scales; (2) the spectral indices between 1.4 and 5 GHz are globally in agreement with optically thin free-free emission, however, ˜30% of these are positive and much greater than -0.1, consistent with a stellar wind scenario; and (3) no major evidence for inverted free-free radiation is found, indicating that this is likely not the cause of the Anomalous Emission in RCW 49. Although our results cannot rule out the spinning dust hypothesis to explain the tentative detection of AME in RCW 49, they emphasize the complexity of astronomical sources that are very well known and studied, such as H ii regions, and suggest that, at least in these objects, the reported excess of emission might be ascribed to alternative mechanisms such as stellar winds and shocks.

  3. Water Masers Embedded in Ultracompact HII Regions in the W75N Cloud Core

    NASA Astrophysics Data System (ADS)

    Hunter, T. R.; Taylor, G. B.; Phillips, T. G.; Felli, M.; Tofani, G.

    1993-05-01

    We present high-resolution radio continuum, H2O maser emission, and molecular line maps of the W75N star-forming region. In addition, we present results from a six-year monitoring campaign of the H2O maser emission from W75N with the 32-m Medicina telescope. Since H2O masers are usually found to be displaced from compact continuum sources in star-forming regions, it has been conjectured that the masers trace young stellar objects at an earlier stage of evolution, perhaps related to energetic molecular outflows. Using the VLA in A-configuration, we find that the 22 GHz H2O maser spots in W75N spatially coincide with weak ultracompact (<1'') radio continuum sources located in the dense molecular cloud core. The masers and continuum sources extend a few arc seconds along a roughly N-S line, a feature also evident as an elongation in the peak of the CS J=7->6 map taken at the CSO. This structure suggests a nearly edge-on, warm, dense disk surrounding the central ionizing source. Past VLBI observations of OH emission have shown a ridge of maser spots along the continuum emission feature, possibly evidence for a shock front in the proposed disk. As a tracer of outflowing molecular gas, we present a map of the CO J=3->2 line wings at 20'' resolution, also from the CSO. Due to foreground contamination of the blue wing, only a monopolar red wing is observed on this scale. We believe W75N to be an important source for further study as it may help unify the various evolutionary features of massive star formation.

  4. 110-111 H2CO and H110α observations towards the giant HII region in cloud complex W43

    NASA Astrophysics Data System (ADS)

    Wu, Gang; Esimbek, Jarken; Zhou, Jian-Jun; Han, Xiao-Hong

    2011-01-01

    The 110-111 formaldehyde (H2CO) absorption line and H110α radio recombination line (H RRL) are observed towards the giant HII region in cloud complex W43. The observations are obtained using the Nanshan 25 m single dish operated by Urumqi Observatory, National Astronomical Observatories of China. A region about 30‧ × 30‧ is observed, which covers the whole HII region in W43. Except for the central 10‧ region, all the other seven points are first observed with the H2CO 110-111 absorption. The column density of the H2CO is calculated, and the H2CO density contours show some differences with the infrared image. Multiple features appear in the H2CO and H RRL which indicate complex structure. The intensities of the H2CO and the velocities of the H110α seem to present a linear correlation, which illustrates that the sphere of influence of the central WR/OB cluster may be much more extended than presently known, since the size is nearly 50 pc.

  5. VizieR Online Data Catalog: JHK photometry of Sh 2-307 HII region (Roman-Lopes, 2009)

    NASA Astrophysics Data System (ADS)

    Roman-Lopes, A.

    2010-02-01

    High-resolution near-infrared (NIR) imaging observations were performed in the direction of Sh 2-307. The data were taken during 2007 November, over eight nights. The NIR spectroscopic observations of the two brightest sources in the cluster region were made during the night of 2007 November 24. (1 data file).

  6. A Faraday Rotation Investigation to Probe the Shells of HII Regions with Associated Stellar Bubbles%A Costa, Allison H.; Spangler, Steven R.; Sink, Joseph R.

    NASA Astrophysics Data System (ADS)

    Costa, Allison H.; Spangler, Steven R.; Sink, Joseph R.

    2015-01-01

    We performed polarimetric observations with the Very Large Array of 11 extra-galactic radio sources with lines of sight through the shell of the Rosette Nebula (VLA project AS1110). This investigation supplements the study of the shell of the Rosette Nebula by Savage et al. (2013). We utilize two methods for calculating the rotation measure (RM) for the new lines of sight. The first is using the traditional method of least-squares fit to χ(λ2), and the second is using RM Synthesis (Brentjens & Bruyn 2005). We present a comparison of the two methods of obtaining RM values, and we find excellent agreement between the two methods. In addition, we discuss a plasma shell model, which is intended to reproduce the sign and magnitude of the observed RM due to the shell, with a new method of determining the model parameters, such as the inner and outer radii and the electron density, for specific lines of sight. This treatment of the model parameters allows us to extend our investigation to HII regions that do not have spherical symmetry, like the Heart Nebula/W4. We describe a new method of fitting a local shell model to specific lines of sight and then calculating the associated RM. By modeling the magnitude of the RM for specific lines of sight, we can better distinguish between a scenario where an observed excess in RM is due to an amplification of the magnetic field or one where it is exclusively due to an increase in the density of the shell. This research was supported at the University of Iowa by grant AST09-07911 and ATM09-56901 from the National Science Foundation.

  7. Modeling and predicting the shape of the far-infrared to submillimeter emission in ultra-compact HII regions and cold clumps

    NASA Astrophysics Data System (ADS)

    Paradis, D.; Mény, C.; Noriega-Crespo, A.; Paladini, R.; Bernard, J.-P.; Bot, C.; Cambrésy, L.; Demyk, K.; Gromov, V.; Rivera-Ingraham, A.; Veneziani, M.

    2014-12-01

    Context. Dust properties are very likely affected by the environment in which dust grains evolve. For instance, some analyses of cold clumps (7-17 K) indicate that the aggregation process is favored in dense environments. However, studying warm (30-40 K) dust emission at long wavelength (λ> 300 μm) has been limited because it is difficult to combine far infrared-to-millimeter (FIR-to-mm) spectral coverage and high angular resolution for observations of warm dust grains. Aims: Using Herschel data from 70 to 500 μm, which are part of the Herschel infrared Galactic (Hi-GAL) survey combined with 1.1 mm data from the Bolocam Galactic Plane Survey (BGPS), we compared emission in two types of environments: ultra-compact HII (UCHII) regions, and cold molecular clumps (denoted as cold clumps). With this comparison we tested dust emission models in the FIR-to-mm domain that reproduce emission in the diffuse medium, in these two environments (UCHII regions and cold clumps). We also investigated their ability to predict the dust emission in our Galaxy. Methods: We determined the emission spectra in twelve UCHII regions and twelve cold clumps, and derived the dust temperature (T) using the recent two-level system (TLS) model with three sets of parameters and the so-called T-β (temperature-dust emissivity index) phenomenological models, with β set to 1.5, 2 and 2.5. Results: We tested the applicability of the TLS model in warm regions for the first time. This analysis indicates distinct trends in the dust emission between cold and warm environments that are visible through changes in the dust emissivity index. However, with the use of standard parameters, the TLS model is able to reproduce the spectral behavior observed in cold and warm regions, from the change of the dust temperature alone, whereas a T-β model requires β to be known. Tables 2, 4, 7 are available in electronic form at http://www.aanda.org

  8. Evidence of Short Timescale Flux Density Variations of UC HII Regions in Sgr B2 Main and North

    NASA Astrophysics Data System (ADS)

    De Pree, C. G.; Peters, T.; Mac Low, M. M.; Wilner, D. J.; Goss, W. M.; Galván-Madrid, R.; Keto, E. R.; Klessen, R. S.; Monsrud, A.

    2015-12-01

    We have recently published observations of significant flux density variations at 1.3 cm in H ii regions in the star-forming regions Sgr B2 Main and North. To further study these variations, we have made new 7 mm continuum and recombination line observations of Sgr B2 at the highest possible angular resolution of the Karl G. Jansky Very Large Array (VLA). We have observed Sgr B2 Main and North at 42.9 GHz and at 45.4 GHz in the BnA configuration (Main) and the A configuration (North). We compare these new data to archival VLA 7 mm continuum data of Sgr B2 Main observed in 2003 and Sgr B2 North observed in 2001. We find that 1 of the 41 known ultracompact and hypercompact H ii regions in Sgr B2 (K2-North) has decreased ∼27% in flux density from 142 ± 14 to 103 ± 10 mJy (2.3σ) between 2001 and 2012. A second source, F3c-Main, has increased ∼30% in flux density from 82 ± 8 to 107 ± 11 mJy (1.8σ) between 2003 and 2012. F3c-Main was previously observed to increase in flux density at 1.3 cm over a longer time period between 1989 and 2012. An observation of decreasing flux density, such as that observed in K2-North, is particularly significant since such a change is not predicted by the classical hypothesis of steady expansion of H ii regions during massive star accretion. Our new observations at 7 mm, along with others in the literature, suggest that the formation of massive stars occurs through time-variable and violent accretion.

  9. Spitzer Space Telescope IRS Spectral Mapping of Photoionized Columns in M16 and the Carina HII Regions

    NASA Astrophysics Data System (ADS)

    Cotera, Angela; Simpson, J. P.; Sellgren, K.; Stolovy, S. R.

    2013-01-01

    Photoevaporated columns of dust and gas - also called elephant trunks, pillars or fingers - are found in the periphery of many H II regions. They have been observed within the Galaxy, the SMC and the LMC. These features are thought to be sites of current star formation, but the question remains whether the columns persist because stars formed in the denser regions prior to interactions with the UV radiation and stellar winds of nearby massive stars, or because of core collapse resulting from these interactions. We have obtained Spitzer IRS spectral maps of three columns within M 16 and three columns within the Carina nebula, to test our understanding of the impact on these transitory features of differing stellar populations and initial conditions. We use the wealth of molecular, atomic and PAH emission lines located within the spectral range of the high resolution IRS modes (9.9-37.2 micron) to determine the excitation state, dust and gas temperatures, and probe the shock characteristics within the columns as a function of location. Using the IRS spectral mapping mode, in conjunction with the CUBISM tool and the CLOUDY H II region model code, we have constructed detailed maps of the accessible emission lines and derived parameters for each column. Mapping the distribution of the physical states of the dust and gas in these columns is enhancing our understanding of the competing processes within these dynamic objects. The data presented here represent the only IRS spectral maps of photoionized pillars.

  10. Heavy Ions In Space (HIIS) experiment

    NASA Technical Reports Server (NTRS)

    Adams, James H., Jr.; Beahm, Lorraine P.; Tylka, Allan J.

    1992-01-01

    The Heavy Ions In Space (HIIS) experiment has two primary objectives: (1) to measure the elemental composition of ultraheavy Galactic cosmic rays, beginning in the tin-barium region of the periodic table; and (2) to study heavy ions which arrive at LDEF below the geomagnetic cutoff, either because they are not fully stripped of electrons or because their source is within the magnetosphere. Both have practical as well as astrophysical consequences. The HIIS experiment used eight thick stacks of plastic track detectors mounted in two trays on the space facing end of LDEF. Since the last LDEF symposium, the statistics were increased of the observations and have extended the analysis to a second stack and to detector sheets near the top of a stack. New results are reported on the detector resolution and on the observations of both stopping and relativistic particles.

  11. Progress report on the Heavy Ions in Space (HIIS) experiment

    NASA Technical Reports Server (NTRS)

    Adams, James H., Jr.; Beahm, Lorraine P.; Boberg, Paul R.; Tylka, Allan J.

    1993-01-01

    One of the objectives of the Heavy Ions In Space (HIIS) experiment is to investigate heavy ions which appear at Long Duration Exposure Facility (LDEF) below the geomagnetic cutoff for fully-ionized galactic cosmic rays. Possible sources of such 'below-cutoff' particles are partially-ionized solar energetic particles, the anomalous component of cosmic rays, and magnetospherically-trapped particles. In recent years, there have also been reports of below-cutoff ions which do not appear to be from any known source. Although most of these observations are based on only a handful of ions, they have led to speculation about 'partially-ionized galactic cosmic rays' and 'near-by cosmic ray sources'. The collecting power of HIIS is order of magnitude larger than that of the instruments which reported these results, so HIIS should be able to confirm these observations and perhaps discover the source of these particles. Preliminary results on below-cutoff heavy-ions are reported. Observations to possible known sources of such ions are compared. A second objective of the HIIS experiment is to measure the elemental composition of ultraheavy galactic cosmic rays, beginning in the tin-barium region of the periodic table. A report on the status of this analysis is presented.

  12. The dielectric study of insulin-loaded reverse hexagonal (H(II)) liquid crystals.

    PubMed

    Mishraki-Berkowitz, T; Ben Ishai, P; Aserin, A; Feldman, Yu; Garti, N

    2015-04-14

    The dielectric behavior of the insulin-loaded HII mesophase (containing GMO-TAG-water-glycerol-insulin) was studied using two empty reference systems (GMO-TAG-water and GMO-TAG-water-glycerol) at a frequency range of 10(-2)-10(6) Hz, and a temperature range of 290-333 K. Three clearly defined relaxation processes were observed and assigned to the reorientation of GMO polar heads, the tangential movement of counterions at the interface, and the movements of TAGs through the lipid tail. Upon addition of glycerol, a heterogeneous inner structure was formed within the HII cylinders: the water-glycerol core surrounded by a water rigid layer. Upon heating, two critical points were detected referring to the dehydration of the GMO heads (at 304 K, similar to the water-filled HII system) and to energetic modifications (at 316 K), resulting in breaking of the water layer allowing on-demand controlled release. Insulin incorporation combined the features of both reference HII systems. Yet, unlike the empty HII systems, insulin perturbed the GMO-water interface while decreasing the movement of the GMO headgroup, and reducing T0 (296 K). No interactions were formed between the dipole of each counterion at the interface region and the matrix (the GMO), fitting the Debye process. Dynamic behavior was observed, pointing to mobility between the hexagonal rods themselves, enabling controlled release from the HII carrier. PMID:25767829

  13. Solubilization of gabapentin into HII mesophases.

    PubMed

    Achrai, Ben; Libster, Dima; Aserin, Abraham; Garti, Nissim

    2011-02-10

    In the present work, we report on the solubilization of gabapentin (GBP) into lyotropic hexagonal mesophases composed of monoolein, tricaprylin, and water. It was demonstrated that the hexagonal structure remained intact up to 2 wt % gabapentin, whereas the lamellar phase coexisted with the hexagonal one in the concentration range of 3-4 wt % of the drug. At gabapentin content of 5-6 wt %, only lamellar phases containing defects such as dislocations and multilamellar vesicles were detected. Incorporation of GBP decreased the lattice parameter of the H(II) mesophase from 56.6 to 50.6 Å, while the structural dimensions of the lamellar phase were not affected. ATR-FTIR analysis suggested enhanced hydrogen bonding between the protonated amine of GBP and the O-H groups of the GMO and the water surrounding in the inner hydrophilic interface region. This led to intercalation of the drug into the water-lipid interface. At higher GBP loads of 4-6 wt %, thermal analysis revealed disordering within the lipid packing, apparently induced by the spatially altered interface area. Rheological measurements correlated the macroscopic features of the systems with alterations on the molecular level and allowed distinguishing between closely related mesophases due to their different rheological characteristics. In vitro transdermal delivery studies showed that the examined mesophases enabled a sustained release of GBP compared to its aqueous solution. Sustained release was more pronounced in the case of the hexagonal mesophase, compared to the lamellar one. PMID:21182317

  14. Molecular gas toward the Bright-Rimmed Cloud BRC 82 illuminated by NGC6231; Triggered star formation associated with HII regions

    NASA Astrophysics Data System (ADS)

    Fukui, Yasuo; Torii, Kazufumi; Akio, Ohama; Soga, Sho

    2012-04-01

    High-mass stars are very energetic and give significant effects on their surroundings. The most remarkable effect among them is triggered star formation by UV radiation from high-mass stars. Bright-rimmed cloud BRC 82, located at ~1.6 kpc from the Sun, is illuminated on its sides by the UV radiation from the remarkable cluster NGC 6231 which contain a number of OB stars. Previous studies indicated that there is on-going star forming regions at the rim of BRC 82, likely triggered by the UV. However, only a few molecular line studies are known to date, and detailed gas distribution have never been revealed yet. Our recent search of molecular gas by using NANTEN2 reveals the dense CO peak in BRC 82, which coincides a high-mass ZAMS star. In this proposal, we intend to investigate the star formation activity and its mechanism in BRC 82 by observing molecular emission lines CO, HCO+, H13CO+, HCN, N2H+, SiO, etc. These observations will reveal the detailed distributions of small and dense condensations related to the star formation. We request 24 hours in total.

  15. Different structures formed at HII boundaries

    NASA Astrophysics Data System (ADS)

    Miao, Jingqi; Cornwall, Paul; Kinnear, Tim

    2015-03-01

    Hydrodynamic simulations on the evolution of molecular clouds (MCs) at HII boundaries are used to show that radiation driven implosion (RDI) model can create almost all of the different morphological structures, such as a single bright-rimmed cloud (BRC), fragment structure and multiple elephant trunk (ET) structures.

  16. Photon Number Conserving Models of HII Bubbles during Reionization

    NASA Astrophysics Data System (ADS)

    Paranjape, Aseem; Choudhury, T. Roy; Padmanabhan, Hamsa

    2016-05-01

    Traditional excursion set based models of HII bubble growth during the epoch of reionization are known to violate photon number conservation, in the sense that the mass fraction in ionized bubbles in these models does not equal the ratio of the number of ionizing photons produced by sources and the number of hydrogen atoms in the intergalactic medium. E.g., for a Planck13 cosmology with electron scattering optical depth τ ≃ 0.066, the discrepancy is ˜15 per cent for xHII = 0.1 and ˜5 per cent for xHII = 0.5. We demonstrate that this problem arises from a fundamental conceptual shortcoming of the excursion set approach (already recognised in the literature on this formalism) which only tracks average mass fractions instead of the exact, stochastic source counts. With this insight, we build an approximately photon number conserving Monte Carlo model of bubble growth based on partitioning regions of dark matter into halos. Our model, which is formally valid for white noise initial conditions (ICs), shows dramatic improvements in photon number conservation, as well as substantial differences in the bubble size distribution, as compared to traditional models. We explore the trends obtained on applying our algorithm to more realistic ICs, finding that these improvements are robust to changes in the ICs. Since currently popular semi-numerical schemes of bubble growth also violate photon number conservation, we argue that it will be worthwhile to pursue new, explicitly photon number conserving approaches. Along the way, we clarify some misconceptions regarding this problem that have appeared in the literature.

  17. Direct measurement of lensing amplification in Abell S1063 using a strongly lensed high redshift HII galaxy

    NASA Astrophysics Data System (ADS)

    Terlevich, Roberto; Melnick, Jorge; Terlevich, Elena; Chávez, Ricardo; Telles, Eduardo; Bresolin, Fabio; Plionis, Manolis; Basilakos, Spyros; Fernández Arenas, David; González Morán, Ana Luisa; Díaz, Ángeles I.; Aretxaga, Itziar

    2016-08-01

    ID11 is an actively star-forming, extremely compact galaxy and Lyα emitter at z = 3.117 that is gravitationally magnified by a factor of ~17 by the cluster of galaxies Hubble Frontier Fields AS1063. The observed properties of this galaxy resemble those of low luminosity HII galaxies or giant HII regions such as 30 Doradus in the Large Magellanic Cloud. Using the tight correlation correlation between the Balmer-line luminosities and the width of the emission lines (typically L(Hβ) - σ(Hβ)), which are valid for HII galaxies and giant HII regions to estimate their total luminosity, we are able to measure the lensing amplification of ID11. We obtain an amplification of 23 ± 11 that is similar within errors to the value of ~17 estimated or predicted by the best lensing models of the massive cluster Abell S1063. We also compiled, from the literature, luminosities and velocity dispersions for a set of lensed compact star-forming regions. There is more scatter in the L-σ correlation for these lensed systems, but on the whole the results tend to support the lensing model estimates of the magnification. Our result indicates that the amplification can be independently measured using the L - σ relation in lensed giant HII regions or HII galaxies. It also supports the suggestion, even if lensing is model dependent, that the L - σ relation is valid for low luminosity high-z objects. Ad hoc observations of lensed star-forming systems are required to determine the lensing amplification accurately.

  18. Starburst in the Interacting HII Galaxy II Zw 40 and in Non-Interacting HII Galaxies

    NASA Astrophysics Data System (ADS)

    Telles, E.

    2010-06-01

    In this poster, I summarize the results of our integral field spectroscopic observations of the nearby prototype of HII galaxies, II Zw 40. Observations with GMOS-IFU on GEMINI-North in the optical allowed us to make a detailed kinematic picture of the central starburst, while SINFONI with adaptive optics on the ESO-VLT gave us a near-IR view of the interplay between the ISM phases. Here, I also address the question that not all starbursts require an external trigger such as a galaxy-galaxy encounter, as it seems to be the case for a fraction of low luminosity HII galaxies. We speculate that these may form stars spontaneously like "popcorn in a pan".

  19. ISS Update: H-II Transfer Vehicle Activities

    NASA Video Gallery

    NASA Public Affairs Officer Josh Byerly talks with NASA astronaut Cady Coleman about the Japanese H-II Transfer Vehicle. Questions? Ask us on Twitter @NASA_Johnson and include the hashtag #askStati...

  20. Propellant loading system of the H-II launch vehicle

    NASA Astrophysics Data System (ADS)

    Takano, Akira; Sameshima, Toru; Oida, Toshihiko; Saki, Nobuo

    National Space Development Agency of Japan (NASDA) has been constructing a new launch facility in Tanegashima Space Center since 1984 for the H-II launch vehicle that is under development. The construction of the launch complex was almost completed by September of 1991, and the validation test of the facility has been conducted using a nonfiring test vehicle called GTV (Ground Test Vehicle). Following to the GTV test, captive firing tests for the 1st stage propulsion system are scheduled to be conducted in 1992 for the verification of the vehicle flight readiness, preparing for the 1st test flight launch of the H-II in 1993. This paper outlines the major portions of the propellant loading systems of the H-II launch facility and summarizes their characteristics obtained through the GTV test.

  1. Optical Spectroscopic Confirmation of OB Star Candidates in HII Regions

    NASA Astrophysics Data System (ADS)

    Tsujimoto, Masahiro; Kobayashi, Naoto

    2007-08-01

    The number of OB stars is the most basic quantity to characterize massive star clusters. We studied several massive clusters using Chandra X-ray observatory and found 30--80 new OB star candidates in RCW49, NGC3603, and NGC3576. The numbers are about 2-3 times larger than those previously known and their spatial distribution extends beyond the central OB associations. We propose a multi-object spectroscopy of these sources to confirm their nature. Using hydrogen and helium emission/absorption lines in the 4000-5000 A spectra and comparing with the OB spectral atlas in the literature, we can determine spectral subtypes and luminosity classes of these sources.

  2. The sulfur doublet in galactic H-II regions

    NASA Technical Reports Server (NTRS)

    Mccracken, C. W.

    1973-01-01

    Spectrographic scans for sulfur doublet intensity in the Orion nebula show that electron density decreases from about 15,000 down to about 1500 electrons per cubic centimeter within a few minutes of arc in both directions from the maximum. There appears to be small-scale structure in the electron density, with variations by a factor of two very common. Satisfactory agreement is obtained for electron density values derived from the oxygen doublet as well as from the sulfur doublet.

  3. Exoplanet Photometry and Spectroscopy with HII/L2

    NASA Astrophysics Data System (ADS)

    Tamura, M.

    2000-12-01

    With the recent discovery of extrasolar planets (exoplanets) around nearby stars by indirect methods, one of the next goals of the exoplanet study is to directly detect the giant exoplanets and to make photometry and spectroscopy. The next decade will be the time to move from discovery to characterization of exoplanet systems. This, however, requires all of high sensitivity, high spatial resolution, and high dynamic range observations at infrared wavelengths, which will be difficult to achieve from the ground. In this paper, we describe a coronagraphic camera and spectrometer for the HII/L2 mission for mid- and far-infrared astronomy and show the photometry and spectroscopy of exoplanets to be one of the most important scientific aims for this mission. The proposed HII/L2 coronagraph will cover the wavelength between 4 and 27 micron, optimized at 5 micron. The plate scale is about 0.06 arcsec, covering a field-of-view of about 1 arcmin by 1 arcmin with a 1024x1024 array detector. Occulting masks of diameter greater than 0.72 arcsec will be available, which enables the observations of exoplanets beyond ~2 AU around nearby (d~5 pc) stars. The coronagraph greatly takes advantage of the single (non-segmented) mirror of the HII/L2 telescope design. A high-efficiency Ge or CdTe grism with a resolution of a few hundreds will be installed for the coronagraphic spectroscopy of the exoplanet atmosphere. Rich spectral features at mid-infrared wavelengths enable us to study various atmospheric components and to make a comparative study of the exoplanets and our solar system planets.

  4. The HII Galaxy Hubble Diagram Strongly Favors Rh = ct over ΛCDM

    NASA Astrophysics Data System (ADS)

    Wei, Jun-Jie; Wu, Xue-Feng; Melia, Fulvio

    2016-08-01

    We continue to build support for the proposal to use HII galaxies (HIIGx) and giant extragalactic HII regions (GEHR) as standard candles to construct the Hubble diagram at redshifts beyond the current reach of Type Ia supernovae. Using a sample of 25 high-redshift HIIGx, 107 local HIIGx, and 24 GEHR, we confirm that the correlation between the emission-line luminosity and ionized-gas velocity dispersion is a viable luminosity indicator, and use it to test and compare the standard model ΛCDM and the Rh = ct Universe by optimizing the parameters in each cosmology using a maximization of the likelihood function. For the flat ΛCDM model, the best fit is obtained with Ω _m= 0.40_{-0.09}^{+0.09}. However, statistical tools, such as the Akaike (AIC), Kullback (KIC) and Bayes (BIC) Information Criteria favor Rh = ct over the standard model with a likelihood of ≈94.8% - 98.8% versus only ≈1.2% - 5.2%. For wCDM (the version of ΛCDM with a dark-energy equation of state wde ≡ pde/ρde rather than wde = wΛ = -1), a statistically acceptable fit is realized with Ω _m=0.22_{-0.14}^{+0.16} and w_de= -0.51_{-0.25}^{+0.15} which, however, are not fully consistent with their concordance values. In this case, wCDM has two more free parameters than Rh = ct, and is penalized more heavily by these criteria. We find that Rh = ct is strongly favored over wCDM with a likelihood of ≈92.9% - 99.6% versus only 0.4% - 7.1%. The current HIIGx sample is already large enough for the BIC to rule out ΛCDM/wCDM in favor of Rh = ct at a confidence level approaching 3σ.

  5. Observações em Radiofreqüências do complexo de Regiões HII Compactas RCW 95

    NASA Astrophysics Data System (ADS)

    Barres de Almeida, Ulisses

    2006-05-01

    In this work we studied the complex of compact HII (CHII) regions RCW 95. The cloud is about 10'x10' and was mapped on the radio continuum emission at 43 GHz; a survey of water lines was also conducted at 22.2 GHz, corresponding to the 616 - 523 rotational transition of this molecule. The observations were made with the 14-meter single-dish antennae of the Itaptinga radio observatory, in Atibaia, ruled by INPE (Nacional Institute for Space Research, Brazil). For the continuum observations we made several scans in right ascension throughout the whole of the source spaced by 1' in declination, that were following combined to produce a map of isotemperatures for the cloud. The study resulted on the identification of resolved radio continuum sources associated with all the three IRAS sources in the region: IRAS 15408-5356, 15411-5352 and 15412-5359, all with far-IR colours characteristics of CHII regions. The water line survey resulted on the positive identification of maser emission associated with the three IRAS sources, supporting the evidences for these regions to harbour massive young stars. Two other unresolved HII regions, unassociated with far-IR sources, were also discovered through detailed analyses of the profiles of the radio continuum scans. The regions associated to the IRAS sources 15408-5356 and 15411-5352 were already known to be regions of massive star formation, whilst the stellar population associated to IRAS 15412-5359 had not been studied before. The discovery of water lines and the presence of a thermal continuum source on this direction suggested that this region could also contain young stars. We then conducted a study of the stellar population inside a region of 2'2' around this IRAS source using near-IR (J, H and K) band images from 2MASS catalogue. Throught this we were able to identify a significant population of massive stars, including one O9V star and some early BV that were charged responsibility for the ionization of the gas in the

  6. Technology of H-II Transfer Vehicle Rendezvous System

    NASA Astrophysics Data System (ADS)

    Kasai, Toru; Ueda, Satoshi; Uematsu, Hirohiko

    The H-II Transfer Vehicle (HTV), which is a Japanese unmanned cargo transfer spacecraft, will deliver supplies to the International Space Station (ISS). The first HTV will be launched in 2009 from the Tanegashima Space Center aboard an H-IIB launch vehicle with up to 6,000kg of supplies. HTV approaches to the ISS and the Space Station Remote Manipulator System (SSRMS), known as Canadarm2, will grapple the HTV and berth it to the ISS. After the supplies, the HTV will then be loaded with waste materials and then separated from the ISS by SSRMS. HTV conducts departure sequence from ISS after release from SSRMS and reentry to the atmosphere. In this paper, technology of HTV automated Guidance, Navigation and Control (GN&C) system is presented.

  7. Molecular dynamics simulations of the lyotropic reverse hexagonal (HII) of Guerbet branched-chain β-D-glucoside.

    PubMed

    Nguan, Hockseng; Ahmadi, Sara; Hashim, Rauzah

    2014-01-01

    Through atomistic molecular dynamic simulations using a GROMOS53a6 force field for the carbohydrate, we studied the lyotropic reverse hexagonal phase HII from a glycolipid, namely the Guerbet branched-chain β-d-glucoside, at 14% and 22% water concentrations. Our simulations showed that at low water concentration (14%) the sugar head group overlapped extensively and protruded into the water channel. In contrast, in the 22% concentration system a water column free from the sugar headgroup ('free' water) was formed as expected for the system close to the limit of maximum hydration. In both concentrations, we found anomalous water diffusion in the xy-plane, i.e. the two-dimensional space confined by the surface of the cylinder. On the other hand, along the z-axis, the water diffusion obeyed the Einstein relation for the 22% system, while for the 14% system it was slightly anomalous. For the 22% system, the diffusion along the z-axis of the 'free' water obeyed the Einstein relation, while that of the 'bound' water is slightly anomalous. The xy-plane displacement of the 'bound' water was higher than that for the 'free' water at times longer than 200 ps, as a consequence of the exchange of water molecules between the two regions. Based on our findings, we proposed an alternative explanation to the observed spatial heterogeneity in the HII phase from probe diffusion by Penaloza et al. (Phys. Chem. Chem. Phys., 2012, 14(15), 5247-5250). We found the extent of contact with water was different at different oxygen atoms within the sugar ring. Generally, a higher probability of hydrogen bonding but a shorter lifetime was found in 22% water compared to the case of 14% water. Finally, we examined the extension and compression of the alkyl chain of a columnar. PMID:24257208

  8. The galactic plane region near l=93o. I. HII region NRAO 655

    NASA Astrophysics Data System (ADS)

    Foster, T.; Routledge, D.

    2001-02-01

    We present new Canadian Galactic Plane Survey radio continuum and λ 21 cm HI line observations of NRAO 655 (G93.4+1.8), plus radio recombination line observations, and optical Hα-line observations. The radio spectrum of NRAO 655 confirms its emission as thermal. From the λ 21 cm HI data we find an atomic hydrogen cavity associated with this object at v ≃ -71.5 km s-1. The cavity corresponds in position and size to the brightest radio continuum emission from NRAO 655. The corresponding kinematic distance is 8.8 kpc, placing NRAO 655 in the Perseus Arm. NRAO 655's linear size is therefore 70 pc × 130 pc. To confirm the λ 21 cm HI velocity we present the first recombination line detection of NRAO 655 (H158 α line, v eq -71 km s-1, and the first observations of a molecular cloud coinciding with NRAO 655 (at v ≃ -72 km s-1. The first optical detection of λ 656 nm Hα emission line features in NRAO 655 is also presented, and the Hα emission line brightness is determined. We suggest that the eastward extension of this strongly asymmetric object originates in a champagne outflow, and we estimate its age. We show that a single early-type star cannot be responsible for the outflow, whereas a group of later-type stars would suffice. A partial HI shell is seen adjacent to the brightest part of NRAO 655; we suggest that it has been formed by dissociation of H2 in the molecular cloud.

  9. VizieR Online Data Catalog: Emission line analysis of HII galaxies (Hoyos+, 2006)

    NASA Astrophysics Data System (ADS)

    Hoyos, C.; Diaz, A. I.

    2006-05-01

    We present a statistical study of a very large sample of HII galaxies taken from the literature. We focus on the differences in several properties between galaxies that show the auroral line [OIII]{lambda}4363 and those that do not present this feature in their spectra. (2 data files).

  10. Transition (LINER/HII) nuclei as evolved Composite (Seyfert 2/Starburst) nuclei

    NASA Astrophysics Data System (ADS)

    Storchi-Bergmann, Thaisa; Brandt, C. H.; Cid Fernandes, R.; Schmitt, H. R.; González Delgado, R.

    2004-11-01

    We compare the circumnuclear stellar population and environmental properies of Seyfert and Composite (Seyfert + Starburst) nuclei with those of LINERs and LINER/HII transition galaxies (TOs), and discuss evidence for evolution from Seyfert/Composite to LINER/TO nuclei.

  11. Results from the Heavy Ions In Space (HIIS) experiment on the ionic charge state of solar energetic particles

    NASA Technical Reports Server (NTRS)

    Tylka, Allan J.; Boberg, Paul R.; Adams, James H., Jr.; Beahm, Lorraine P.; Kleis, Thomas

    1995-01-01

    It has long been known that low-energy solar energetic particles (SEP's) are partially-ionized. For example, in large, so-called 'gradual' solar energetic particle events, at approximately 1 MeV/nucleon the measured mean ionic charge state, Q, of Fe ions is 14.1 +/- 0.2, corresponding to a plasma temperature of approximately 2 MK in the coronal or solar-wind source material. Recent studies, which have greatly clarified the origin of solar energetic particles and their relation to solar flares, suggest that ions in these SEP events are accelerated not at a flare site, but by shocks propagating through relatively low-density regions in the interplanetary medium. As a result, the partially-ionized states observed at low energies are expected to continue to higher energies. However, up to now there have been no high-energy measurements of ionic charge states to confirm this notion. We report here HIIS observations of Fe-group ions at 50-600 MeV/nucleon, at energies and fluences which cannot be explained by fully-ionized galactic cosmic rays, even in the presence of severe geomagnetic cutoff suppression. Above approximately 200 MeV/nucleon, all features of our data -- fluence, energy spectrum, elemental composition, and arrival directions -- can be explained by the large SEP events of October 1989, provided that the mean ionic charge state at these high energies is comparable to the measured value at approximately 1 MeV/nucleon. By comparing the HIIS observations with measurements in interplanetary space in October 1989, we determine the mean ionic charge state of SEP Fe ions at approximately 200-600 MeV/nucleon to be Q = 13.4 plus or minus 1.0, in good agreement with the observed value at approximately 1 MeV/nucleon. The source of the ions below approximately 200 MeV/nucleon is not yet clear. Partially-ionized ions are less effectively deflected by the Earth's magnetic field than fully-ionized cosmic rays and therefore have greatly enhanced access to low-Earth orbit

  12. Observations of the Ionized, Neutral, and Molecular Components Associated with an Expanding H II Region

    NASA Astrophysics Data System (ADS)

    Lebrón, Mayra E.; Rodríguez, Luis F.; Lizano, Susana

    2001-10-01

    We present H92α, HI 21 cm, NH3 (1, 1) and NH3 (2, 2) lines and radio continuum observations toward the compact HII region G111.61+0.37, located in the region Sharpless 159. The dense molecular gas (traced by the ammonia lines) in the vicinity of G111.61+0.37 is distributed in clumps indicating considerable inhomogeneity in the molecular gas. A warm (Trot=47 K) ammonia clump is located just in front of the head of the cometary HII region. The photodissociated region associated to this compact HII region was detected in the HI 21 cm line. The neutral region is extended in the direction opposite to the dense molecular gas. The velocity distribution of the neutral gas suggests that the HI region is expanding in a champagne flow resembling that of the HII region, although with much lower velocities.

  13. Condições físicas em galáxias HII

    NASA Astrophysics Data System (ADS)

    Kehrig, C.; Telles, E.; Cuisinier, F.

    2003-08-01

    Galáxias HII são galáxias anãs de baixa luminosidade que apresentam alta taxa de formação estelar. Seus espectros são dominados por intensas linhas de emissão devido à fotoionização pela presença de um grande número de estrelas do tipo O e B. Nós apresentamos um catálogo espectrofotométrico de 111 galáxias HII observadas no telescópio 1.52m do ESO com o espectrógrafo Boller & Chivens. Determinamos propriedades estatísticas da amostra e derivamos condições físicas (temperatura eletrônica, densidade eletrônica) e abundâncias químicas. Para algumas galáxias, fomos também capazes de resolver espacialmente regiões de formação estelar individuais e determinar propriedades espectroscópicas para estas regiões separadamente, o que nos permitiu avaliar as flutuações das condições físico-químicas dentro das galáxias HII. Em particular, vimos que apesar das galáxias HII apresentarem formação estelar espalhada ao longo do corpo da galáxia, são objetos quimicamente homogêneos. A fim de estudar a evolução temporal dos objetos durante o tempo de vida das estrelas ionizantes construimos também alguns diagramas relacionando razões de linhas de emissão com a largura equivalente de Hb (EW(Hb)). Para interpretar tais diagramas utilizamos modelos de fotoionização para populações estelares integradas. Concluímos que as galáxias HII não correspondem a simples idéia de um burst instantâneo envolvido por um gás opaco aos fótons ionizantes e com densidade constante. As relações observadas entre razões de linhas e EW(Hb) podem ser melhor compreendidas se as galáxias HII apresentarem populações estelares mais velhas, que contribuem para o contínuo óptico observado.

  14. Structural effects of insulin-loading into HII mesophases monitored by electron paramagnetic resonance (EPR), small angle X-ray spectroscopy (SAXS), and attenuated total reflection Fourier transform spectroscopy (ATR-FTIR).

    PubMed

    Mishraki, Tehila; Ottaviani, Maria Francesca; Shames, Alexander I; Aserin, Abraham; Garti, Nissim

    2011-06-30

    Insulin entrapment within a monoolein-based reverse hexagonal (H(II)) mesophase was investigated under temperature-dependent conditions at acidic (pH 3) and basic (pH 8) conditions. Studying the structure of the host H(II) system and the interactions of insulin under temperature-dependent conditions has great impact on the enhancement of its thermal stabilization and controlled release for the purposes of transdermal delivery. Small angle X-ray spectroscopy (SAXS) measurements show that pH variation and/or insulin entrapment preserve the hexagonal structure and do not influence the lattice parameter. Attenuated total reflection Fourier transform spectroscopy (ATR-FTIR) spectra indicate that, although insulin interacts with hydroxyl groups of GMO in the interface region, it is not affected by pH variations. Hence different microenvironments within the H(II) mesophase were monitored by a computer-aided electron paramagnetic resonance (EPR) analysis using 5-doxylstearic acid (5-DSA) as a pH-dependent probe. The microviscosity, micropolarity, order of systems, and distribution of the probes in different microenvironments were influenced by three factors: temperature, pH, and insulin solubilization. When the temperature is increased, microviscosity and order parameters decreased at both pH 3 and 8, presenting different decrease trends. It was found that, at pH 3, the protein perturbs the lipid structure while "pushing aside" the un-ionized 5-DSA probe to fit into the narrow water cylinders. At the interface region (pH 8), the probe was distributed in two differently structured environments that significantly modifies by increasing temperature. Insulin loading within the H(II) mesophase decreased the order and microviscosity of both the microenvironments and increased their micropolarity. Finally, the EPR analysis also provides information about the unfolding/denaturation of insulin within the channel at high temperatures. PMID:21591776

  15. Chandra observations of the HII complex G5.89-0.39 and TeV gamma-ray source HESSJ1800-240B

    NASA Astrophysics Data System (ADS)

    Hampton, E. J.; Rowell, G.; Hofmann, W.; Horns, D.; Uchiyama, Y.; Wagner, S.

    2016-09-01

    We present the results of our investigation, using a Chandra X-ray observation, into the stellar population of the massive star formation region G5.89-0.39, and its potential connection to the coincident TeV gamma-ray source HESSJ1800-240B. G5.89-0.39 comprises two separate HII regions G5.89-0.39A and G5.89-0.39B (an ultra-compact HII region). We identified 159 individual X-ray point sources in our observation using the source detection algorithm wavdetect. 35 X-ray sources are associated with the HII complex G5.89-0.39. The 35 X-ray sources represent an average unabsorbed luminosity (0.3-10 keV) of ∼1030.5erg /s, typical of B7-B5 type stars. The potential ionising source of G5.89-0.39B known as Feldt's star is possibly identified in our observation with an unabsorbed X-ray luminosity suggestive of a B7-B5 star. The stacked energy spectra of these sources is well-fitted with a single thermal plasma APEC model with kT ∼ 5 keV, and column density NH = 2.6 ×1022cm-2 (AV ∼ 10). The residual (source-subtracted) X-ray emission towards G5.89-0.39A and B is about 30% and 25% larger than their respective stacked source luminosities. Assuming this residual emission is from unresolved stellar sources, the total B-type-equivalent stellar content in G5.89-0.39A and B would be 75 stars, consistent with an earlier estimate of the total stellar mass of hot stars in G5.89-0.39. We have also looked at the variability of the 35 X-ray sources in G5.89-0.39. Ten of these sources are flagged as being variable. Further studies are needed to determine the exact causes of the variability, however the variability could point towards pre-main sequence stars. Such a stellar population could provide sufficient kinetic energy to account for a part of the GeV to TeV gamma-ray emission in the source HESSJ1800-240B. However, future arc-minute angular resolution gamma-ray imaging will be needed to disentangle the potential gamma-ray components powered by G5.89-0.39 from those powered by the

  16. Optical Spectroscopic Confirmation of OB Star Candidates in HII Regions (2)

    NASA Astrophysics Data System (ADS)

    Tsujimoto, Masahiro; Kobayashi, Naoto; Wang, Junfeng

    2008-02-01

    The number of OB stars (earlier than B2) is one of the most basic quantities to characterize massive star clusters. We studied several massive clusters using the Chandra X-ray Observatory and found 40--60 new OB star candidates in NGC6357, NGC6231, and NGC6334. The numbers are much larger than those previously known and their spatial distribution extends beyond the central OB associations. We propose a multi-object spectroscopy of these sources to confirm their nature. Using hydrogen and helium emission/absorption lines in the 4000-5000 A spectra and comparing with the OB spectral atlas in the literature, we can determine spectral sub-types and luminosity classes of these sources.

  17. Spatial and temporal variations of reddening parameters toward HII regions in the Milky Way galaxy

    NASA Astrophysics Data System (ADS)

    Vargas Alvarez, Carlos A.

    The purpose of this thesis is to determine if the value of the total-to-selective extinction ratio, RV, has spatial and temporal variations as dust is modified by UV photons. Historically this value has been assumed to be 3.1 after averaging the values along different sightlines in the Milky Way Galaxy. This work will also demonstrate, that for areas of recent star formation with heavy extinction a proper study can not be done when assuming the nominal value, but a local value of RV must first be determined. For this purpose I will analyze the reddening parameters RV and A V toward the massive cluster Westerlund 2 and several mid-IR bubbles located in the G38.91-0.42 complex. Three reddening laws that made different assumptions about RV are applied to the spectral energy distribution (SED) of the observed stars. These SEDs are compared to the available optical and IR photometry searching for the RV and AV that minimizes the chi 2 of the fit.

  18. Emission line analysis of two giant HII regions in M33

    NASA Astrophysics Data System (ADS)

    Jamet, L.; Stasińska, G.; Perez, E.; Gonalez-Delgado, R.; Vilchez, J.

    2002-06-01

    I will present the results of the study of these two objects, based on observations made by E. Perez, R Gonzalez-Delgado and J Vilchez (IAA, Granada). These long-slit, high signal-to-noise spectra, completed by archived data from HST, IUE and ISO and ground-based images, will alow to achieve an accurate modelization of the nebulae. Their ionising sources are modelled with Starburst99; then, Stasińska's code PHOTO is to be used to understand the ionization conditions of the two nebulae.

  19. VizieR Online Data Catalog: MWA Survey of Galactic HII regions (Hindson+, 2016)

    NASA Astrophysics Data System (ADS)

    Hindson, L.; Johnston-Hollitt, M.; Hurley-Walker, N.; Callingham, J. R.; Su, H.; Morgan, J.; Bell, M.; Bernardi, G.; Bowman, J. D.; Briggs, F.; Cappallo, R. J.; Deshpande, A. A.; Dwarakanath, K. S.; For, B.-Q.; Gaensler, B. M.; Greenhill, L. J.; Hancock, P.; Hazelton, B. J.; Kapin, A. D.; Kaplan, D. L.; Lenc, E.; Lonsdale, C. J.; McKinley, B.; McWhirter, S. R.; Mitchell, D. A.; Morales, M. F.; Morgan, E.; Oberoi, D.; Offringa, A.; Ord, S. M.; Procopio, P.; Prabu, T.; Udaya Shankar, N.; Srivani, K. S.; Staveley-Smith, L.; Subrahmanyan, R.; Tingay, S. J.; Wayth, R. B.; Webster, R. L.; Williams, A.; Williams, C. L.; Wu, C.; Zheng, Q.

    2016-06-01

    We use observations that utilise the MWA interferometer, which is the low frequency precursor for the Square Kilometre Array (SKA), located at the Murchison Radio-astronomy Observatory in Western Australia. The observations presented in this study were obtained as part of the GLEAM survey (Wayth et al., 2015PASA...32...25W). (1 data file).

  20. VizieR Online Data Catalog: Spectroscopy of NGC3310 HII regions (Miralles-Caballero+, 2014)

    NASA Astrophysics Data System (ADS)

    Miralles-Caballero, D.; Diaz, A. I.; Rosales-Ortega, F. F.; Perez-Montero, E.; Sanchez, S. F.

    2015-01-01

    NGC 3310 observations were carried out with the 3.5m telescope of the Calar Alto Observatory using the Postdam Multi-Aperture Spectrograph (PMAS) in the PMAS fibre package mode (PPAK). This was part of the PINGS (Rosales-Ortega et al., 2010MNRAS.405..735R). We retrieved publicly available broad-band imaging of this galaxy in order to perform an absolute flux re-calibration. Specifically, we used the Sloan Digital Sky Survey (SDSS, http://www.sdss.org/) broad-band g- and r-filter images (with a spatial resolution of about 1-arcsec) and an HST (http://www.stsci.edu/hst/) image taken with the Wide Field Planetary Camera 2 (WFPC2, with a spatial resolution of about 0.05-arcsec) using the F439W filter (similar to B Johnson). We also obtained UV images of the galaxy. In particular, taken with the UVW2 and UVM2 filters (with effective wavelengths of 2087 and 2297Å, respectively), mounted on the OM camera on board the XMM-Newton satellite. (3 data files).

  1. VizieR Online Data Catalog: M33 HII regions SED (Relano+, 2013)

    NASA Astrophysics Data System (ADS)

    Relano, M.; Verley, S.; Perez, I.; Kramer, C.; Calzetti, D.; Xilouris, E. M.; Boquien, M.; Abreu-Vicente, J.; Combes, F.; Israel, F.; Tabatabaei, F. S.; Braine, J.; Buchbender, C.; Gonzalez, M.; Gratier, P.; Lord, S.; Mookerjea, B.; Quintana-Lacaci, G.; van der Werf, P.

    2013-09-01

    To investigate the continuum UV emission of M 33, we used the data from GALEX, in particular the data distributed by de Paz et al. (2007, Cat. J/ApJS/173/185). To trace the ionised gas, we used the narrow-line Hα image of M 33 obtained by Greenawalt (1998, Ph.D. Thesis, New Mexico state University). Dust emission can be investigated through the mid-IR (MIR) and FIR data of M 33 obtained with the Spitzer Infrared Array Camera (IRAC) and Multiband Imaging Photometer (MIPS). (3 data files).

  2. Low energy ions in the heavy ions in space (HIIS) experiment on LDEF.

    PubMed

    Kleis, T; Tylka, A J; Boberg, P R; Adams, J H; Beahm, L P

    1996-01-01

    We present data from the Lexan top stacks in the Heavy Ions In Space (HIIS) experiment which was flown for six years (April 1984-Jan 1990) onboard the LDEF spacecraft in 28.5 degrees orbit at about 476 km altitude. HIIS was built of passive (i.e. no timing resolution) plastic track detectors which collected particles continuously over the entire mission. In this paper we present data on low energy heavy ions (10 < or = Z, 20MeV/nuc < E < 200 MeV/nuc). These ions are far below the geomagnetic cutoff for fully ionized ions in the LDEF orbit even after taking into account the severe cutoff suppression caused by occasional large geomagnetic storms during the LDEF mission. Our preliminary results indicate an unusual elemental composition of trapped particles in the inner magnetosphere during the LDEF mission, including both trapped anomalous cosmic ray species (Ne, Ar) and other elements (such as Mg and Fe) which are not found in the anomalous component of cosmic rays. The origin of the non-anomalous species is not understood, but they may be associated with the solar energetic particle events and geomagnetic disturbances of 1989. PMID:11540364

  3. HII 2407: An Eclipsing Binary Revealed By K2 Observations of the Pleiades

    NASA Astrophysics Data System (ADS)

    David, Trevor J.; Stauffer, John; Hillenbrand, Lynne A.; Cody, Ann Marie; Conroy, Kyle; Stassun, Keivan G.; Pope, Benjamin; Aigrain, Suzanne; Gillen, Ed; Collier Cameron, Andrew; Barrado, David; Rebull, L. M.; Isaacson, Howard; Marcy, Geoffrey W.; Zhang, Celia; Riddle, Reed L.; Ziegler, Carl; Law, Nicholas M.; Baranec, Christoph

    2015-11-01

    The star HII 2407 is a member of the relatively young Pleiades star cluster and was previously discovered to be a single-lined spectroscopic binary. It is newly identified here within Kepler/K2 photometric time series data as an eclipsing binary system. Mutual fitting of the radial velocity and photometric data leads to an orbital solution and constraints on fundamental stellar parameters. While the primary has arrived on the main sequence, the secondary is still pre-main sequence and we compare our results for the M/M⊙ and R/R⊙ values with stellar evolutionary models. We also demonstrate that the system is likely to be tidally synchronized. Follow-up infrared spectroscopy is likely to reveal the lines of the secondary, allowing for dynamically measured masses and elevating the system to benchmark eclipsing binary status.

  4. Perfis de temperatura eletrônica em regiões HII

    NASA Astrophysics Data System (ADS)

    Copetti, M. V. F.

    2003-08-01

    As flutuações de temperatura eletrônica em regiões HII, inicialmente propostas para explicar as discrepâncias entre os valores de temperatura obtidos por diferentes métodos, têm sido apontadas como a causa mais provável das enormes diferenças encontradas entre as abundâncias químicas medidas através de linhas excitadas colisionalmente e de linhas de recombinação. Recentemente têm sido reportadas tentativas de detecção e quantificação diretas das flutuações de temperatura eletrônica através de medidas ponto a ponto, obtidas por meio de espectroscopia de fenda longa, das razões de linhas [OIII]l4263/l5007 e [NII]l5755/l6584, principais sensores de temperatura. Neste trabalho, utilizamos o código numérico de fotoionização Cloudy para avaliar a confiabilidade desse procedimento. Concluímos que, para valores de densidade eletrônica e de temperatura efetiva da estrela ionizante típicos das regiões HII, os perfis superficiais de temperatura obtidos via medidas do sensor [OIII]l4263/l5007 são bons traçadores dos gradientes internos de temperatura eletrônica. Já os perfis de temperatura eletrônica medidos por meio da razão [NII]l5755/l6584 não reproduzem os gradientes verdadeiros de temperatura.

  5. Quasar H II Regions During Cosmic Reionization

    SciTech Connect

    Alvarez, Marcelo A.; Abel, Tom; /KIPAC, Menlo Park

    2007-03-30

    Cosmic reionization progresses as HII regions form around sources of ionizing radiation. Their average size grows continuously until they percolate and complete reionization. We demonstrate how this typical growth can be calculated around the largest, biased sources of UV emission such as quasars by further developing an analytical model based on the excursion set formalism. This approach allows us to calculate the sizes and growth of the HII regions created by the progenitors of any dark matter halo of given mass and redshift with a minimum of free parameters. Statistical variations in the size of these pre-existing HII regions are an additional source of uncertainty in the determination of very high redshift quasar properties from their observed HII region sizes. We use this model to demonstrate that the transmission gaps seen in very high redshift quasars can be understood from the radiation of only their progenitors and associated clustered small galaxies. The fit requires the epoch of overlap to be at z = 5.8 {+-} 0.1. This interpretation makes the transmission gaps independent of the age of the quasars observed. If this interpretation were correct it would raise the prospects of using radio interferometers currently under construction to detect the epoch of reionization.

  6. RpoHII Activates Oxidative-Stress Defense Systems and Is Controlled by RpoE in the Singlet Oxygen-Dependent Response in Rhodobacter sphaeroides▿ †

    PubMed Central

    Nuss, Aaron M.; Glaeser, Jens; Klug, Gabriele

    2009-01-01

    Photosynthetic organisms need defense systems against photooxidative stress caused by the generation of highly reactive singlet oxygen (1O2). Here we show that the alternative sigma factor RpoHII is required for the expression of important defense factors and that deletion of rpoHII leads to increased sensitivity against exposure to 1O2 and methylglyoxal in Rhodobacter sphaeroides. The gene encoding RpoHII is controlled by RpoE, and thereby a sigma factor cascade is constituted. We provide the first in vivo study that identifies genes controlled by an RpoHII-type sigma factor, which is widely distributed in the Alphaproteobacteria. RpoHII-dependent genes encode oxidative-stress defense systems, including proteins for the degradation of methylglyoxal, detoxification of peroxides, 1O2 scavenging, and redox and iron homeostasis. Our experiments indicate that glutathione (GSH)-dependent mechanisms are involved in the defense against photooxidative stress in photosynthetic bacteria. Therefore, we conclude that systems pivotal for the organism's defense against photooxidative stress are strongly dependent on GSH and are specifically recognized by RpoHII in R. sphaeroides. PMID:18978062

  7. H-II Transfer Vehicle (HTV) and the Operations Concept for Extravehicular Activity (EVA) Hardware

    NASA Technical Reports Server (NTRS)

    Chullen, Cinda

    2010-01-01

    With the retirement of the Space Shuttle fleet imminent in 2011, a new concept of operations will become reality to meet the transportation challenges of the International Space Station (ISS). The planning associated with the retirement of the Space Shuttle has been underway since the announcement in 2004. Since then, several companies and government entities have had to look for innovative low-cost commercial orbital transportation systems to continue to achieve the objectives of ISS delivery requirements. Several options have been assessed and appear ready to meet the large and demanding delivery requirements of the ISS. Options that have been identified that can facilitate the challenge include the Russian Federal Space Agency's Soyuz and Progress spacecraft, European Space Agency's Automated Transfer Vehicle (ATV), the Japan Aerospace Exploration Agency's (JAXA's) H-II Transfer Vehicle (HTV) and the Boeing Delta IV Heavy (DIV-H). The newest of these options is the JAXA's HTV. This paper focuses on the HTV, mission architecture and operations concept for Extra-Vehicular Activities (EVA) hardware, the associated launch system, and details of the launch operations approach.

  8. H-II Transfer Vehicle (HTV) and the Operations Concept for Extravehicular Activity (EVA) Hardware

    NASA Technical Reports Server (NTRS)

    Chullen, Cinda; Blome, Elizabeth; Tetsuya, Sakashita

    2011-01-01

    With the retirement of the Space Shuttle fleet imminent in 2011, a new operations concept will become reality to meet the transportation challenges of the International Space Station (ISS). The planning associated with the retirement of the Space Shuttle has been underway since the announcement in 2004. Since then, several companies and government entities have had to look for innovative low-cost commercial orbital transportation systems to continue to achieve the objectives of ISS delivery requirements. Several options have been assessed and appear ready to meet the large and demanding delivery requirements of the ISS. Options that have been identified that can facilitate the challenge include the Russian Federal Space Agency's Soyuz and Progress spacecraft, European Space Agency's Automated Transfer Vehicle (ATV), and the Japan Aerospace Exploration Agency's (JAXA s) H-II Transfer Vehicle (HTV). The newest of these options is the JAXA's HTV. This paper focuses on the HTV, mission architecture and operations concept for Extra-Vehicular Activities (EVA) hardware, the associated launch system, and details of the launch operations approach.

  9. Molecular dynamics approach to water structure of HII mesophase of monoolein

    NASA Astrophysics Data System (ADS)

    Kolev, Vesselin; Ivanova, Anela; Madjarova, Galia; Aserin, Abraham; Garti, Nissim

    2012-02-01

    The goal of the present work is to study theoretically the structure of water inside the water cylinder of the inverse hexagonal mesophase (HII) of glyceryl monooleate (monoolein, GMO), using the method of molecular dynamics. To simplify the computational model, a fixed structure of the GMO tube is maintained. The non-standard cylindrical geometry of the system required the development and application of a novel method for obtaining the starting distribution of water molecules. A predictor-corrector schema is employed for generation of the initial density of water. Molecular dynamics calculations are performed at constant volume and temperature (NVT ensemble) with 1D periodic boundary conditions applied. During the simulations the lipid structure is kept fixed, while the dynamics of water is unrestrained. Distribution of hydrogen bonds and density as well as radial distribution of water molecules across the water cylinder show the presence of water structure deep in the cylinder (about 6 Å below the GMO heads). The obtained results may help understanding the role of water structure in the processes of insertion of external molecules inside the GMO/water system. The present work has a semi-quantitative character and it should be considered as the initial stage of more comprehensive future theoretical studies.

  10. Molecular dynamics approach to water structure of H(II) mesophase of monoolein.

    PubMed

    Kolev, Vesselin; Ivanova, Anela; Madjarova, Galia; Aserin, Abraham; Garti, Nissim

    2012-02-21

    The goal of the present work is to study theoretically the structure of water inside the water cylinder of the inverse hexagonal mesophase (H(II)) of glyceryl monooleate (monoolein, GMO), using the method of molecular dynamics. To simplify the computational model, a fixed structure of the GMO tube is maintained. The non-standard cylindrical geometry of the system required the development and application of a novel method for obtaining the starting distribution of water molecules. A predictor-corrector schema is employed for generation of the initial density of water. Molecular dynamics calculations are performed at constant volume and temperature (NVT ensemble) with 1D periodic boundary conditions applied. During the simulations the lipid structure is kept fixed, while the dynamics of water is unrestrained. Distribution of hydrogen bonds and density as well as radial distribution of water molecules across the water cylinder show the presence of water structure deep in the cylinder (about 6 Å below the GMO heads). The obtained results may help understanding the role of water structure in the processes of insertion of external molecules inside the GMO∕water system. The present work has a semi-quantitative character and it should be considered as the initial stage of more comprehensive future theoretical studies. PMID:22360250

  11. Star forming regions in gas-rich SO galaxies

    NASA Technical Reports Server (NTRS)

    Pogge, Richard W.; Eskridge, Paul B.

    1987-01-01

    The first results of an H alpha imaging survey of HI rich SO galaxies, which were searched for HII regions and other sources of emission, are presented. The charge coupled device H alpha interference filter images were made of 16 galaxies. Eight of these galaxies show evidence for on-going star formation, one has nuclear emission but no HII regions, and the remaining seven have no emissions detected within well defined upper limits. With the exception of one notably peculiar galaxy in which the emission from HII regions appears pervasive, the HII regions are either organized into inner-disk rings or randomly distributed throughout the disk. A few of these galaxies are found to be clearly not SO's; or peculiar objects atypical of the SO class. Using simple models star formation rates (SFRs) and gas depletion times from the observed H alpha fluxes were estimated. In general, the derived SFRs are much lower than those found in isolated field spiral galaxies and the corresponding gas depletion time scales are also longer.

  12. Characteristics of low energy ions in the Heavy Ions In Space (HIIS) experiment

    NASA Technical Reports Server (NTRS)

    Kleis, Thomas; Tylka, Allan J.; Boberg, Paul R.; Adams, James H., Jr.; Beahm, Lorraine P.

    1995-01-01

    We present preliminary data on heavy ions (Z greater than or equal to 10) detected in the topmost Lexan sheets of the track detector stacks of the Heavy Ions in space (HIIS) experiment (M0001) on LDEF. The energy interval covered by these observations varies with the element, with (for example) Ne observable at 18-100 MeV nuc and Fe at 45-200 MeV/nuc. All of the observed ions are at energies far below the geomagnetic cutoff for fully-ionized particles at the LDEF orbit. Above 50 MeV/nuc (where most of our observed particles are Fe), the ions arrive primarily from the direction of lowest geomagnetic cutoff. This suggests that these particles originate outside the magnetosphere from a source with a steeply-falling spectrum and may therefore be associated with solar energetic particle (SEP) events. Below 50 MeV/nuc, the distribution of arrival directions suggests that most of the observed heavy ions are trapped in the Earth's magnetic field. Preliminary analysis, however, shows that these trapped heavy ions have a very surprising composition: they include not only Ne and Ar, which are expected from the trapping of anomalous cosmic rays (ACR's), but also Mg and Si, which are not part of the anomalous component. Our preliminary analysis shows that trapped heavy ions at 12 less than or equal to Zeta less than or equal to 14 have a steeply-falling spectrum, similar to that reported by the Kiel experiment (exp 1,2,3) on LDEF (M0002) for trapped Ar and Fe at E less than 50 MeV/nuc. The trapped Mg, Si, and Fe may also be associated with SEP events, but the mechanism by which they have appeared to deep in the inner magnetosphere requires further theoretical investigation.

  13. MS_RHII-RSD, a Dual-Function RNase HII-(p)ppGpp Synthetase from Mycobacterium smegmatis

    PubMed Central

    Murdeshwar, Maya S.

    2012-01-01

    In the noninfectious soil saprophyte Mycobacterium smegmatis, intracellular levels of the stress alarmones guanosine tetraphosphate and guanosine pentaphosphate, together termed (p)ppGpp, are regulated by the enzyme RelMsm. This enzyme consists of a single, bifunctional polypeptide chain that is capable of both synthesizing and hydrolyzing (p)ppGpp. The relMsm knockout strain of M. smegmatis (ΔrelMsm) is expected to show a (p)ppGpp null [(p)ppGpp0] phenotype. Contrary to this expectation, the strain is capable of synthesizing (p)ppGpp in vivo. In this study, we identify and functionally characterize the open reading frame (ORF), MSMEG_5849, that encodes a second functional (p)ppGpp synthetase in M. smegmatis. In addition to (p)ppGpp synthesis, the 567-amino-acid-long protein encoded by this gene is capable of hydrolyzing RNA·DNA hybrids and bears similarity to the conventional RNase HII enzymes. We have classified this protein as actRelMsm in accordance with the recent nomenclature proposed and have named it MS_RHII-RSD, indicating the two enzymatic activities present [RHII, RNase HII domain, originally identified as domain of unknown function 429 (DUF429), and RSD, RelA_SpoT nucleotidyl transferase domain, the SYNTH domain responsible for (p)ppGpp synthesis activity]. MS_RHII-RSD is expressed and is constitutively active in vivo and behaves like a monofunctional (p)ppGpp synthetase in vitro. The occurrence of the RNase HII and (p)ppGpp synthetase domains together on the same polypeptide chain is suggestive of an in vivo role for this novel protein as a link connecting the essential life processes of DNA replication, repair, and transcription to the highly conserved stress survival pathway, the stringent response. PMID:22636779

  14. Static firing test results of the H-I and H-II launch vehicle development at the Tanegashima Space Center

    NASA Astrophysics Data System (ADS)

    Sekita, Ryuichi; Haraguchi, Yoshitaka; Konno, Akira; Saito, Takashi

    1991-10-01

    In addition to its H-I launch vehicle complex, Japan's Tanegashima Space Center (TSC) encompasses three static-firing test facilities. These facilities will respectively be used in the course of the H-II launch vehicle development program for the static firing of strap-on boosters, the MB-3 liquid-fueled engine, and the Yoshinobu static firing test facility for the LE-7 staged combustion-cycle first-stage engine. Results are presented from static firings for the three H-II components which have been conducted to date. The first flight of the H-II, following completion of static tests at the aforementioned TSC facilities, is scheduled for 1993.

  15. Order and dynamics in the lamellar L alpha and in the hexagonal HII phase. Dioleoylphosphatidylethanolamine studied with angle-resolved fluorescence depolarization.

    PubMed Central

    van Langen, H; Schrama, C A; van Ginkel, G; Ranke, G; Levine, Y K

    1989-01-01

    Fluorescence depolarization techniques are used to determine the molecular order and reorientational dynamics of the probe molecule TMA-DPH embedded in the lamellar L alpha and the hexagonal HII phases of lipid/water mixtures. The thermotropically induced L alpha----HII phase transition of the lipid DOPE is used to obtain macroscopically aligned samples in the hexagonal HII phase at 45 degrees C from samples prepared in the lamellar L alpha phase at 7 degrees C. The interpretation of angle-resolved fluorescence depolarization experiments on these phases, within the framework of the rotational diffusion model, yields the order parameters (P2) and (P4), and the diffusion constants for the reorientational motions. The reorientational motion rates of the TMA-DPH molecules in the hexagonal HII phase are comparable with those in the lamellar L alpha phase. Furthermore, the lateral diffusion of the probe molecule on the surface of the lipid/water cylinder in the hexagonal phase is found to be considerably slower than the reorientational motion. PMID:2720082

  16. Impact of climate change on the Hii River basin and salinity in Lake Shinji: a case study using the SWAT model and a regression curve

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The impacts of climate change on water resources were analysed for the Hii River basin and downstream Lake Shinji. The variation between saline and fresh water within these systems means that they encompass diverse ecosystems. Changes in evapotranspiration (ET), snow water equivalent, discharge into...

  17. VizieR Online Data Catalog: Atlas of HI absorption toward HII regions in SGPS I (Brown+, 2014)

    NASA Astrophysics Data System (ADS)

    Brown, C.; Dickey, J. M.; Dawson, J. R.; McClure-Griffiths, N. M.

    2014-05-01

    The SGPS covers 325deg2 of the Galactic plane over the fourt first Galactic quadrants (SGPS I and SGPS II, respectively). The SGPS provides three distinct data products: Parkes continuum-subtracted cubes, with an angular resolution of 15', combined Parkes and ATCA continuum-subtracted HI cubes (2.2'), and combined Parkes and ATCA cubes containing continuum emission (~1.6'). For this work we use the continuum-included combined Parkes-ATCA data. These cubes were specifically produced for HI absorption studies, as they provide accurately calibrated data at the highest angular resolution of the SGPS. All SGPS continuum and line cube data are available online via the Australia Telescope National Facility (ATNF) HI Surveys archive. (2 data files).

  18. VizieR Online Data Catalog: PN and HII regions of West and East of NGC 3109 (Pena+, 2007)

    NASA Astrophysics Data System (ADS)

    Pena, M.; Richer, M. G.; Stasińska, G.

    2007-03-01

    Six files (fits format, 16MB) containing images of the West (W) and East (E) zones of NGC 3109 are presented. The images are a combination of frames obtained with the ESO Very Large Telescope and the Focal Reducer Spectrograph FORS1. All the frames were obtained on 29 November and 1 December 2005, with air masses smaller than 1.16 and seeing better than 0.7 arcsec. They constitute the pre-imaging of the ESO program ID 076.B-0166(A). Central coordinates of images are: West side (images named NGC3109W-xxxx.fits) RA=10:02:54.5, DE=-26:09:22, equinox 2000. East side (images named NGC3109E-xxx.fits) RA=10:03:19.8, DE=-26:09:32, equinox 2000. The image size is 6.8x6.8arcmin2. (3 data files).

  19. Physical Conditions in Low Ionization Regions of the Orion Nebula

    NASA Technical Reports Server (NTRS)

    Baldwin, J. A.; Crotts, A.; DuFour, R. J.; Ferland, G. J.; Heathcote, S.; Hester, J. J.; Korista, K. T.; Martin, P. J.; ODell, C. R.

    1996-01-01

    We reexamine the spectroscopic underpinnings of recent claims that low ionization (O(I)) and (Fe(II)) lines from the Orion H(II) region are produced in a region where the iron-carrying grains have been destroyed and the electron density is surprisingly high. Our new HST and CTIO observations show that previous reported detections of(O(I)) lambda 5577 were strongly affected by telluric emission. Our line limits consistent with a moderate density (approx. 10(exp 4)/cu. cm photoionized gas. We show that a previously proposed model of the Orion H(II) region reproduces the observed (O(I)) and (Fe(II)) spectrum. These lines are fully consistent with formation in a moderate density dusty region.

  20. H(II) mesophase and peptide cell-penetrating enhancers for improved transdermal delivery of sodium diclofenac.

    PubMed

    Cohen-Avrahami, Marganit; Aserin, Abraham; Garti, Nissim

    2010-06-01

    This study develops a novel transdermal delivery vehicle for the enhanced delivery of sodium diclofenac (Na-DFC). The system utilizes the advantages of reversed hexagonal lyotropic liquid crystals (H(II)LC), combined with a peptide cell penetration enhancer (CPE), creating together an adaptable system that provides versatile options in the field of transdermal delivery. This enhancer peptide is based on a family of amphipatic peptides that exhibit improved membrane permeability. Franz permeation cell experiments revealed that the peptide enhancer (RALA) improved Na-DFC skin penetration of the liquid crystal 2.2-fold. We studied the structural effects of RALA solubilization on the H(II) mesophase. RALA acts as a chaotropic agent, interfering in the structure of the water, and causes a measurable swelling of the aqueous cylinders by 5A. Small angle X-ray scattering (SAXS) and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) measurements reveal enhanced hydration of the glycerol monooleate (GMO) headgroups and a 6.5% increase in the fraction of non-freezable water resulting from RALA incorporation. RALA caused a gradual increase in the GMO effective headgroup area due to the hydration, leading eventually to a transform of the hexagonal structure towards a lamellar one. Circular dichroism and ATR-FTIR measurements showed a conservation of the peptide structure when incorporated into the H(II) mesophase. The combined H(II)LC-CPE systems can serve as high potential vehicles for a variety of drugs, as they can easily be modified by varying the composition and temperature, according to the required dose and delivery features. PMID:20189781

  1. National and regional health information infrastructures: making use of information technology to promote access to evidence.

    PubMed

    Dykes, Patricia; Bakken, Suzanne

    2004-01-01

    The vision for national and regional health information infrastructures (HII) includes provision of a framework that is supportive of access and integration of health information with the goal of improving the health and safety of individuals, public health systems, and nations. Internationally, prominent examples of national and regional HIIs exist that provide a means for achievement of this goal. However, to fully realize benefits, an explicit mechanism is needed for linking national and regional HIIs with existing knowledge, automated processes and evaluation of the ability of HIIs to meet the information needs of primary recipients. Using the United States' Na-tion Health Information Infrastructure (NHII) as an example, the authors describe expansion of the conceptual framework to explicitly acknowledge the role of access to evidence at the overlap between the three dimensions of the NHII to create an "evidence-based" link between interrelated components. The role of national measures in setting e-communication goals and evaluating the evolving infrastructure in meeting informational needs of users is discussed. Additionally, automated knowledge management tools such as practice guidelines are presented as a means by which access to critical information is delivered to users, in a format that is appropriate for their health literacy level and that provides adequate support for informed decision making. PMID:15361000

  2. Impact of suspended sediment and nutrient loading from land uses against water quality in the Hii River basin, Japan

    NASA Astrophysics Data System (ADS)

    Somura, H.; Takeda, I.; Arnold, J. G.; Mori, Y.; Jeong, J.; Kannan, N.; Hoffman, D.

    2012-07-01

    SummaryLake Shinji lies in eastern Shimane Prefecture, and is typical of brackish lakes in Japan. Water quality of the lake does not meet the expected environmental standards for total nitrogen (TN) and total phosphorus (TP), even though the national and prefectural governments have tried to improve water quality by developing maintenance scenarios for sewage, plant effluent, agricultural activity, and forestry. Consequently, detailed data of nutrient loading to the lake from river inflows is crucial to support strategies for improving the lake water environment. The Hii River contributes approximately 80% of the discharge flowing into the lake. In this study, we examine the Hii River catchment with a focus on land uses such as paddy fields, upland fields, residential areas, and forestry. Average annual discharges of suspended sediment (SS), TN, and TP loads were determined at Otsu, near the outlet of the basin into Lake Shinji. We also determined average yield per unit area of SS, TN, and TP loads from each land use. Yields per unit area from upland areas were the greatest, whereas yields from forests were the lowest. Forests were the largest contributor of SS, TN, and TP in the basin, because of its dominant land area. Upland fields had the second largest impact on these loads in the basin, because fertilizer applied to the fields is a major source of nitrogen (N) and phosphorus (P). Large differences in yields per unit area between fine and rainy day conditions were also observed, especially for SS and TP loads. Furthermore, we determined that a major pathway of N to the river was through groundwater, regardless of land use, whereas P was transported to the river with sediments, especially in paddy and upland fields. Based on these analyses, it will be difficult to reduce the SS load discharge in the basin in the future, because forestry is the major source. In contrast, N and P load reductions are straightforward, because the primary source is agricultural, and

  3. Development of X-ray computed tomography inspection facility for the H-II solid rocket boosters

    NASA Astrophysics Data System (ADS)

    Sasaki, M.; Fujita, T.; Fukushima, Y.; Shimizu, M.; Itoh, S.; Satoh, A.; Miyamoto, H.

    The National Space Development Agency of Japan (NASDA) initiated the development of an X-ray computed tomography (CT) equipment for the H-II solid rocket boosters (SRBs) in 1987 for the purpose of minimizing inspection time and achieving high cost-effectiveness. The CT facility has been completed in Jan. 1991 in Tanegashima Space Center for the inspection of the SRBs transported from the manufacturer's factory to the launch site. It was first applied to the qualification model SRB from Feb. to Apr. in 1991. Through the CT inspection of the SRB, it has been confirmed that inspection time decreased significantly compared with the X-ray radiography method and that even an unskilled inspector could find various defects. As a result, the establishment of a new reliable inspection method for the SRB has been verified. In this paper, the following are discussed: (1) the defect detectability of the CT equipment using a dummy SRB with various artificial defects, (2) the performance comparison between the CT method and the X-ray radiography method, (3) the reliability of the CT equipment, and (4) the radiation shield design of the nondestructive test building.

  4. Physical conditions of a HII galaxy with extraordinarily dense nucleus: Mrk996

    NASA Astrophysics Data System (ADS)

    Telles, E.; Thuan, T. X.; Izotov, Y. I.; Carrasco, E. R.

    2014-10-01

    We present an integral field spectroscopic study with the Gemini Multi-Object Spectrograph (GMOS) of the unusual blue compact dwarf (BCD) galaxy Mrk 996. We show through velocity and dispersion maps, emission-line intensity and ratio maps, and by a new technique of electron density limit imaging that the ionization properties of different regions in Mrk 996 are correlated with their kinematic properties. From the maps, we can spatially distinguish a very dense high-ionization zone with broad lines in the nuclear region, and a less dense low-ionization zone with narrow lines in the circumnuclear region. Four kinematically distinct systems of lines are identified in the integrated spectrum of Mrk 996, suggesting stellar wind outflows from a population of Wolf-Rayet (WR) stars in the nuclear region, superposed on an underlying rotation pattern. From the intensities of the blue and red bumps, we derive a population of ˜ 473 late nitrogen (WNL) stars and ˜ 98 early carbon (WCE) stars in the nucleus of Mrk 996, resulting in a high N(WR)/N(O+WR) of 0.19. We derive, for the outer narrow-line region, an oxygen abundance 12+log(O/H)=7.94 ± 0.30 (˜ 0.2 Z_{odot}) by using the direct T_e method derived from the detected narrow [O III]λ 4363 line. The nucleus of Mrk 996 is, however, nitrogen-enhanced by a factor of ˜ 20, in agreement with previous CLOUDY modeling. This nitrogen enhancement is probably due to nitrogen-enriched WR ejecta, but also to enhanced nitrogen line emission in a high-density environment. Although we have made use here of two new methods - Principal Component Analysis (PCA) tomography and a method for mapping low- and high-density clouds - to analyze our data, new methodology is needed to further exploit the wealth of information provided by integral field spectroscopy.

  5. Magnetic field in Photodissociation Regions (PDRs) : A case study of PDR in NGC 2024

    NASA Astrophysics Data System (ADS)

    Anish Roshi, D.; Goss, Miller; Jeyakumar, S.

    2015-01-01

    We present images of C110α and H110α radio recombination line (RRL) emission at 4.8 GHz and images of H166α, C166α and X166α RRL emission at 1.4 GHz, observed toward the starforming region NGC 2024. The 1.4 GHz image with angular resolution ˜ 70 arcsec is obtained using VLA data. The 4.8 GHz image with angular resolution ˜ 17 arcsec is obtained by combining VLA and GBT data. These images reveal that the spatial distributions of C110α line emission is confined to the southern rim of the HII region close to the ionization front whereas the C166α line emission is extended in the north-south direction across the HII region. The LSR velocity of the C110α line is 10.3 kms similar to that of lines observed from molecular material located at the far side of the HII region. This similarity suggests that the photo dissociation region (PDR) responsible for C110α line emission is at the far side of the HII region. The LSR velocity of C166α is 8.8 kms. This velocity is comparable with the velocity of molecular absorption lines observed from the foreground gas, suggesting that the PDR is at the near side of the HII region. Non-LTE models for carbon line forming regions are presented. Typical properties of the foreground PDR are T_{PDR} ˜ 100 K, n_e^{PDR} ˜ 5 \\cm3, n_H ˜ 1.7 × 10^4 \\cm3, path length l ˜ 0.06 pc and those of the far side PDR are T_{PDR} ˜ 200 K, n_e^{PDR} ˜ 50 \\cm3, n_H ˜ 1.7 × 10^5 \\cm3, l ˜ 0.03 pc. Our modeling indicates that the far side PDR is located within the HII region. Using the method proposed by Roshi (2007), we estimate magnetic field strength in the foreground PDR to be 60 μG and that in the far side PDR to be 220 μG. Our field estimates compare well with the values obtained from OH Zeeman observations toward NGC 2024.

  6. The temperature and ionization structure of the emitting gas in HII galaxies: implications for the accuracy of abundance determinations

    NASA Astrophysics Data System (ADS)

    Hägele, Guillermo F.; Pérez-Montero, Enrique; Díaz, Ángeles I.; Terlevich, Elena; Terlevich, Roberto

    2006-10-01

    We propose a methodology to perform a self-consistent analysis of the physical properties of the emitting gas of HII galaxies adequate to the data that can be obtained with the 21st century technology. This methodology requires the production and calibration of empirical relations between the different line temperatures that should supersede currently used ones based on very simple, and poorly tested, photoionization model sequences. As a first step to reach these goals, we have obtained simultaneous blue to far red long-slit spectra with the William Herschel Telescope (WHT) of three compact HII galaxies selected from the Sloan Digital Sky Survey (SDSS) Data Release 2 (DR2) spectral catalogue using the INAOE Virtual Observatory superserver. Our spectra cover the range from 3200 to 10500Å, including the Balmer jump, the [OII]λλ3727, 29Å lines, the [SIII]λλ9069, 9532Å doublet as well as various weak auroral lines such as [OIII]λ4363Å and [SIII]λ6312Å. For the three objects, we have measured at least four line temperatures, T([OIII]), T([SIII]), T([OII]) and T([SII]), and the Balmer continuum temperature T(Bac). These measurements and a careful and realistic treatment of the observational errors yield total oxygen abundances with accuracies between 5 and 9 per cent. These accuracies are expected to improve as better calibrations based on more precise measurements, both on electron temperatures and densities, are produced. We have compared our obtained spectra with those downloaded from the SDSS DR3 finding a satisfactory agreement. The analysis of these spectra yields values of line temperatures and elemental ionic and total abundances which are in general agreement with those derived from the WHT spectra, although for most quantities they can only be taken as estimates since, due to the lack of direct measurements of the required lines, theoretical models had to be used whose uncertainties are impossible to quantify. The ionization structure found for the

  7. From the H II Region to the Molecular Cloud: Determining Physical Conditions in Star Forming Regions

    NASA Astrophysics Data System (ADS)

    Abel, N. P.

    2004-12-01

    Infrared missions such as Spitzer offer new insights into the chemical evolution and star formation history of the universe. Although objects such as starburst galaxies, which are among the most luminous objects in the universe, are the primary focus, OMC-1, a lower luminosity region with superb spatial resolution, serves as a benchmark to test the physics of newly formed O stars interacting with the surrounding molecular environment. The classical approach in determining conditions in the ionized, photodissociated, and molecular regions is to treat each problem separately. In actuality, however, this is a single continuous phenomenon, linked through the transport of gas and radiation. Here we self-consistently calculate the physical conditions and emission from the hot HII region to the cold, molecular gas as a continuous hydrostatic layer. The ion states of the first 30 elements, along with the abundances of 70 molecules, are determined with the temperature and electron density. The grain physics is treated self-consistently, with grain charge transfer, single photon heating, and PAH effects all included. Additionally, level populations of all the rotational/vibrational levels of the ground electronic state of molecular hydrogen are determined (see the dissertation talk of Gargi Shaw). As a benchmark, we consider the physical conditions through OMC-1 1' west of the Trapezium, where emission-line observations of the HII region and the PDR/molecular cloud all exist. Accurately interpreting this spectrum will give us confidence that we can apply our calculations to more luminous and distant starburst galaxies. We predict the sometimes significant contribution of the HII region to important PDR emission-line diagnostics. This has consequences for the interpretation of IR observations, the deduced values of n(H) and G0 in PDRs, and hence the overall conditions in star forming regions. All calculations were developed with the spectral synthesis code Cloudy, which is

  8. Evolução química de galáxias HII anãs

    NASA Astrophysics Data System (ADS)

    Ferraresi, M., Jr.; Cuisinier, F.; Telles, E.

    2003-08-01

    Galáxias HII anãs são galáxias de baixa massa, com alto conteúdo de gás, e se encontram em uma fase intensa de formação estelar. A taxa de formação estelar está tão alta nestas galáxias que não pode ter se mantido durante sua vida inteira. O tempo máximo de duração do episódio atual de formação estelar deve ser no máximo de algumas dezenas de milhões de anos, bem inferior à idade destas galáxias. Isto leva naturalmente a idéia de que já aconteceram surtos anteriores. Abundâncias químicas oferecem uma ferramenta poderosa para investigar a história evolutiva destas galáxias, porque aumentam de geração em geração estelar. O hidrogênio, o oxigênio, o nitrogênio produzem algumas das linhas mais importantes em um gás foto-ionizado, permitindo a determinação das abundâncias destes elementos facilmente. A dispersão das abundâncias em oxigênio e nitrogênio é significativa, sendo maior que os erros observacionais. O oxigênio é produzido em estrelas massivas, que explodem quase instâneamente, enquanto o nitrogênio é produzido em estrelas de massa intermediária, que só o liberam depois de um atraso de @ 500 mihões de anos. Construímos um modelo de evolução química semi-analítico, utilizando rendimentos empíricos baseados nas abundâncias observadas destes dois elementos. Conseguimos através deste modelo rudimentar explicar nas galáxias de mais baixas metalicidades as abundâncias de oxigênio e de nitrogênio, assim como a dispersão dos dados observacionais devida a formação estelar descontínua, e isto com um número baixo de surtos (1 ou 2, no máximo 3).

  9. Unit cell structure of water-filled monoolein into inverted hexagonal (H(II)) mesophase modeled by molecular dynamics.

    PubMed

    Kolev, Vesselin L; Ivanova, Anela N; Madjarova, Galia K; Aserin, Abraham; Garti, Nissim

    2014-05-22

    The study investigates the unit cell structure of inverted hexagonal (H(II)) mesophase composed of monoolein (1-monoolein, GMO) and water using atomistic molecular dynamics methods without imposing any restraints on lipid and water molecules. Statistically meaningful and very contrast images of the radial mass density distribution, scrutinizing also the separate components water, monoolein, the polar headgroups of the lipids, the double bond, and the termini of the hydrocarbon chain (the tail), are obtained. The lipid/water interface structure is analyzed based on the obtained water density distribution, on the estimated number of hydrogen bonds per monoolein headgroup, and on the headgroup-water radial distribution functions. The headgroup mass density distribution demonstrates hexagonal shape of the monoolein/water interface that is well-defined at higher water/monoolein ratios. Water interacts with the headgroups by forming a three-layer diffusive mass density distribution, and each layer's shape is close to hexagonal, which is an indication of long-range structural interactions. It is found that the monoolein headgroups form a constant number of hydrogen bonds leaving an excessive amount of water molecules outside the first lipid coordination sphere. Furthermore, the quantity of water at the monoolein/water interface increases steadily upon extension of the unit cell, so the interface should have a very dynamic structure. Investigation of the hydrocarbon residues reveals high compression and well-expressed structuring of the tails. The tails form a very compressed and constrained structure of defined layers across the unit cell with properties corresponding to a more densely packed nonpolar liquid (oil). Due to the hexagonal shape the 2D packing frustration is constant and does not depend on the water content. All reported structural features are based on averaging of the atomic coordinates over the time-length of the simulation trajectories. That kind of

  10. Parsec-scale X-ray flows in high-mass star-forming regions

    NASA Astrophysics Data System (ADS)

    Townsley, L. K.; Broos, P. S.; Feigelson, E. D.; Garmire, G. P.

    The Chandra X-ray Observatory is providing remarkable new views of massive star-forming regions, revealing all stages in the life cycle of high-mass stars and their effects on their surroundings. We present a Chandra tour of several high-mass star-forming regions, highlighting physical processes that characterize the life of a cluster of high-mass stars, from deeply-embedded cores too young to have established an HII region to superbubbles so large that they shape our views of galaxies. Along the way we see that X-ray observations reveal hundreds of stellar sources powering great HII region complexes, suffused by both hard and soft diffuse X-ray structures caused by fast O-star winds thermalized in wind-wind collisions or by termination shocks against the surrounding media. Finally, we examine the effects of the deaths of high-mass stars that remained close to their birthplaces, exploding as supernovae within the superbubbles that these clusters created. We present new X-ray results on W51 IRS2E and 30 Doradus and we introduce new data on Trumpler 14 in Carina and the W3 HII region complexes W3 Main and W3(OH).

  11. An atlas of H-alpha-emitting regions in M33: A systematic search for SS433 star candidates

    NASA Technical Reports Server (NTRS)

    Calzetti, Daniela; Kinney, Anne L.; Ford, Holland; Doggett, Jesse; Long, Knox S.

    1995-01-01

    We report finding charts and accurate positions for 432 compact H-alpha emitting regions in the Local Group galaxy M 33 (NGC 598), in an effort to isolate candidates for an SS433-like stellar system. The objects were extracted from narrow band images, centered in the rest-frame H-alpha (lambda 6563 A) and in the red continuum at 6100 A. The atlas is complete down to V approximately equal to 20 and includes 279 compact HII regions and 153 line emitting point-like sources. The point-like sources undoubtedly include a variety of objects: very small HII regions, early type stars with intense stellar winds, and Wolf-Rayet stars, but should also contain objects with the characteristics of SS433. This extensive survey of compact H-alpha regions in M 33 is a first step towards the identification of peculiar stellar systems like SS433 in external galaxies.

  12. An infrared study of the bi-polar outflow region GGD 12-15

    NASA Technical Reports Server (NTRS)

    Harvey, P. M.; Wilking, B. A.; Joy, M.; Lester, D. F.

    1984-01-01

    Infrared observations from 1 to 100 microns are presented for the region associated with a bipolar CO outflow source near the nebulous objects GGD 12 to 15. A luminous far-infrared source was found associated with a radio-continuum source in the area. This object appears to be a compact HII region around a nearly main-sequence BO star. A faint 20 micron source was also discovered at the position of an H2O maser 3O deg northwest of the HII region. This object appears to be associated with but not coincident with a 2 micron reflection nebula. This structure serves as evidence for a non-spherically symmetric, possibly disk-like dust distribution around the exciting star for the maser. This object probably powers the bi-polar CO outflow although its luminosity is less than 10% that of the star which excites the compact HII region. A number of other 2 micron sources found in the area are probably members of a recently formed cluster.

  13. Discovery of Very High Energy Gamma-Ray Emission in the W 28 (G6.4-0.1) Region and Multiwavelength Comparisons

    SciTech Connect

    Rowell, G.; Brion, E.; Reimer, O.; Moriguchi, Y.; Fukui, Yasuo; Djannati-Atai, A.; Funk, S.; /Stanford U., HEPL /KIPAC, Menlo Park

    2007-10-29

    H.E.S.S. observations of the old-age (>10{sup 4} yr; {approx} 0.5 degree diameter) composite supernova remnant (SNR)W28 reveal very high energy (VHE) {gamma}-ray emission situated at its northeastern and southern boundaries. The northeastern VHE source (HESS J1801-233) is in an area where W 28 is interacting with a dense molecular cloud, containing OH masers, local radio and X-ray peaks. The southern VHE sources (HESS J1800-240 with components labeled A, B and C) are found in a region occupied by several HII regions, including the ultracompact HII region W 28A2. Our analysis of NANTEN CO data reveals a dense molecular cloud enveloping this southern region, and our reanalysis of EGRET data reveals MeV/GeV emission centered on HESS J1801-233 and the northeastern interaction region.

  14. Panoramic spectroscopy of galaxies with star-formation regions. a study of SBS 1202 + 583

    NASA Astrophysics Data System (ADS)

    Hakopian, S. A.; Balayan, S. K.; Dodonov, S. N.; Moiseev, A. V.; Smirnova, A. A.

    2012-03-01

    The methods of panoramic (3D) spectroscopy are used by us in a detailed study of galaxies with ongoing star formation chosen from among objects in seven selected fields of the Second Byurakan Survey (SBS). This article deals with the irregular galaxy SBS 1202 + 583, which our classification scheme identifies as being in a continuous phase of star formation. Observations were made with the panoramic spectrographs MPFS at the 6-m telescope of the Special Astrophysical Observatory (SAO) of the Russian Academy of Sciences and VAGR at the 2.6-m telescope of the Byurakan Astrophysical Observatory (BAO) in Armenia. The data are used to construct maps of the radiative fluxes in the continuum and various emission lines. Special attention is devoted to analyzing the emission in the H α hydrogen recombination line and in the forbidden low-ionization doublets of nitrogen [NII] λλ6548, 6583 and sulfur [SII] λλ6716, 6731, and the ratios of the intensities of the forbidden lines to H α. The observable characteristics (size, H α fluxes, etc.) of nine HII regions are studied. The estimated current rates of star formation in the individual HII regions based on the H α fluxes lie within the range of 0.3-1.2⨀ M /year. The dependence of the ratio of the intensities of the emission in these above mentioned forbidden doublets on the rate of star formation in the HII regions is found.

  15. Disk Evaporation in Star Forming Regions

    NASA Technical Reports Server (NTRS)

    Hollenbach, David; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    Young stars produce sufficient ultraviolet photon luminosity and mechanical luminosity in their winds to significantly affect the structure and evolution of the accretion disks surrounding them. The Lyman continuum photons create a nearly static, ionized, isothermal 10(exp 4) K atmosphere forms above the neutral disk at small distances from the star. Further out, they create a photoevaporative flow which relatively rapidly destroys the disk. The resulting slow (10-50 km/s) ionized outflow, which persists for approx. greater than 10(exp 5) years for disk masses M(sub d) approx. 0.3M(sub *), may explain the observational characteristics of many ultracompact HII regions. We compare model results to the observed radio free-free spectra and luminosities of ultracompact HII regions and to the interesting source MWC349, which is observed to produce hydrogen masers. We apply the results to Ae and Be stars in order to determine the lifetimes of disks around such stars. We also apply the results to the early solar nebula to explain the the dispersal of the solar nebula and the differences in hydrogen content in the giant planets. Finally, we model the small bright objects ("proplyds") observed in the Orion Nebula as disks around young, low mass stars which are externally illuminated by the UV photons from the nearby massive star Theta(sup 1) C.

  16. An ATCA radio-continuum study of the Small Magellanic Cloud - IV. A multifrequency analysis of the N66 region

    NASA Astrophysics Data System (ADS)

    Reid, W. A.; Payne, J. L.; Filipović, M. D.; Danforth, C. W.; Jones, P. A.; White, G. L.; Staveley-Smith, L.

    2006-04-01

    Traditional identification of supernova remnants (SNRs) include the use of radio spectral index, optical spectral studies (including strong [SII], [NII], [OI], [OII] and [OIII] lines) and X-ray co-identifications. Each of these can have significant limitations within the context of a particular SNR candidate and new identification methods are continually sought. In this paper, we explore subtraction techniques by Ye, Turtle and Kennicutt to remove thermal emission estimated from Hα flux from radio-continuum images. The remaining non-thermal emission allows the identification of SNRs embedded within these HII regions. Subtraction images of the N66 region in the Small Magellanic Cloud (SMC) using Hα wide-field optical CCD images from the Curtis Schmidt Telescope and the recent Australia Telescope Compact Array (ATCA)/Parkes radio-continuum (1420, 2370, 4800 and 8640MHz) data are presented as an example. These show three SNRs (B0057 - 724, B0056 - 724 and B0056 - 725) separated from their surrounding HII radio emission. 2.3-m dual-beam spectrograph long-slit spectra from selected regions within N66 suggest the presence of an additional SNR with no radio or X-ray emission. Radio spectral index, [SII]/Hα ratio and archived Chandra images of N66 combine to give a more coherent picture of this region, confirming B0057 - 724 as an SNR. The N66 nebula complex is divided into 10 components, composed separately of these SNRs and HII regions.

  17. Physical parameters of the Orion Bar photodissociation region from radio recombination line observations at 8 mm.

    NASA Astrophysics Data System (ADS)

    Tsivilev, A. P.

    2014-10-01

    Observations of carbon (C), hydrogen and helium (H, He) radio recombination lines (RRLs) at four positions in the Orion Bar photodissociation region (PDR) and toward the center of Orion A have been performed with the RT-22 radio telescope (Pushchino) at 8 mm. The physical parameters of the PDR at these points have been estimated by comparing the carbon RRLs and infrared CII and OI lines. A hydrogen number density in the range 1.2-3.1 × 10^5 cm^-3 and a mean size of the region along the line of sight (L) in the range 0.006-0.04 pc have been derived. The PDR temperature decreases with increasing distance from the exciting star (θ 1 C Ori) from 210-230 to 140-150 K (a distance of ≃5'). The data obtained confirm the increase in the PDR size along the line of sight toward the Orion Bar, where, however, L has turned out to be less than the available values in the literature, which can be explained by the presence of clumps in the PDR. A density jump is evident in the Orion Bar region. The PDR zone encompasses the core of the HII region by a thin layer and extends farther, delineating the boundary and the ionization front of the core of the HII region in the Orion Bar and further out the boundary between the halo of the HII region and the molecular cloud. The derived emission measure (EM) toward the Orion Bar has been compared with other C RRL observations. The EM measured from carbon RRLs is EM ≃ 100(±50%) pc cm^-6, imposing constraints on the possible two-component PDR structure. Estimates show that the star θ 1 C Ori is quite sufficient as a carbon ionization source in the Orion Bar PDR. Some of the data on the ionized hot gas (HII) in this direction have been obtained from H and He RRLs. In particular, the radial velocities (V lsr) of the HII region are blueshifted with respect to V lsr of the PDR by 10-17 km s^-1, while the relative ionized helium abundance decreases with increasing distance from the star, indicating that the helium ionization zone is smaller

  18. Chandra Discoveries in High-mass Star-forming Regions

    NASA Astrophysics Data System (ADS)

    Townsley, L. K.; Broos, P. S.; Feigelson, E. D.; Garmire, G. P.

    2004-08-01

    Chandra is providing remarkable new views of high-mass star-forming regions, revealing all stages in the life cycle of high-mass stars and their effects on their surroundings. We present a Chandra/ACIS tour of several high-mass star-forming regions, highlighting physical processes that characterize the life of a cluster of high-mass stars, from deeply-embedded cores too young to have established an HII region to superbubbles so large that they shape our views of galaxies. Along the way we see that X-ray observations reveal hundreds of stellar sources powering great HII region complexes, suffused by both hard and soft diffuse X-ray structures caused by fast O-star winds thermalized in wind-wind collisions or by termination shocks against the surrounding media. Finally, we examine the effects of the deaths of high-mass stars that remained close to their birthplaces, exploding as supernovae within the superbubbles that these clusters created.

  19. The PAH emission properties of an ensemble of UCHII regions in W49A.

    NASA Astrophysics Data System (ADS)

    Stock, D.; Peeters, E.; Choi, W. D.-Y.

    The galactic star-forming region W49A is considered to be the Milky Way analogue of extragalactic starburst environments. W49A contains an ensemble of ultra compact HII (UCHII) regions along with copious diffuse material and young stars. Spitzer/IRS mapping observations of a 3‧ x 2‧ subsection of W49A have been obtained in the 5-14 µ m range. These observations cover approximately 20% of W49A and encompass many of the previously detected UCHII regions along with diffuse structure, all of which display the characteristic mid infrared (MIR) PAH emission. The spectral properties of the emission at each pixel of the map have been analyzed, allowing the detailed comparison of the MIR emission of the different UCHII regions and surrounding material. The UCHII regions possess different properties in terms of their stellar populations (and hence the incident UV fields), ionization, extinction etc. resulting in different PAH emission characteristics. These results are compared to the characteristics of the diffuse PAH emission surrounding W49A, along with previous studies of PAHs in HII regions. Furthermore, we investigate the link between the PAH emission and the physical conditions of the HII regions (e.g. line ratio proxies for ionization). Finally, we show that the spatial structure of the various MIR emission components in these UCHII regions (e.g. the continuum emission, PAH bands and forbidden lines) can be simply modeled assuming emission from spherically symmetric shells. This model can recover the parameters of the emitting regions, e.g. the characteristic radii and thickness of the emitting shells. Model fits then show that the 8.6 µ m PAH emission originates closer to the exciting stars than the other PAH bands. In addition, for one of the UCHII regions, we find that the 6.2 and 7.7 PAH bands no longer correlate on the lines of sight near the center, an effect noted previously in only one other object, also an HII region. It is also shown that the

  20. Looking Closely at ``Medusa": Star Forming Regions in NGC 4194

    NASA Astrophysics Data System (ADS)

    Weistrop, D.; Eggers, D.; Nelson, C. H.; Kaiser, M. E.

    2000-05-01

    The ``Medusa" (NGC 4194, Mrk 201) is a blue compact galaxy, with strong far infrared and radio emission. Ground-based observations exhibit a distorted image with a tidal tail and regions of strong star formation. A population of massive O and early B stars is evident from the IUE spectra (Kinney, et al. 1993). Malkan et al.'s (1998) HST survey of Seyfert and starburst galaxies notes NGC 4194 is an HII galaxy with lumpy HII regions and knots. The central starburst is apparently produced by a galaxy merger. As part of an investigation of star formation in interacting galaxies, we have obtained ultraviolet and visible images of the central regions of NGC 4194 with the Space Telescope Imaging Spectrograph on HST. Imaging was obtained in two ultraviolet (FUV-MAMA+F25QTZ, NUV-MAMA+F25CN182) and one visible (CCD+F28X50LP) band. Individual star forming knots (at HST resolution) have been identified. We present sizes and luminosities for the individual knots, and the knot luminosity function. We compare our data to current starburst models to constrain stellar ages and populations. Knot characteristics as a function of location in the galaxy will also be discussed. This work has been supported in part by NASA, under contract NAS5-31231.

  1. Looking Closely at "Medusa": Star Forming Regions in NGC 4194

    NASA Technical Reports Server (NTRS)

    Weistrop, D.; Eggers, D.; Nelson, C. H.; Kaiser, M. E.

    2004-01-01

    The "Medusa" (NGC 4194, Mrk 201) is a blue compact galaxy, with strong far infrared and radio emission. Ground-based observations exhibit a distorted image with a tidal tail and regions of strong star formation. A population of massive O and early B stars is evident from the IUE spectra HST survey of Seyfert and starburst galaxies notes NCG 4194 is an HII galaxy with lumpy HII regions and knots. The central starburst is apparently produced by a galaxy merger. As part of an investigation of star formation in interacting galaxies, we have obtained ultraviolet and visible images of the central regions of NGC 4194 with the Space Telescope Imaging Spectrograph on HST. Imaging was obtained in two ultraviolet (FUV-MAMA+F25QTZ, NUV-MAMA+F25CN182) and one visible (CCD+F28X50LP) band. Individual star forming knots (at HST resolution) have been identified. We present sized and luminosities for the individual knots, and the knot luminosity function. We compare our data to current starburst models to constrain stellar ages and populations. Knot characteristics as a function of location in the galaxy will also be discussed.

  2. HYGEIAnet: the integrated regional health information network of Crete.

    PubMed

    Orphanoudakis, Stelios

    2004-01-01

    The healthcare environment is currently changing and the health sector is being transformed to meet new challenges and to benefit from new opportunities. Priorities for the 21st century ought to be set based on emerging dominant trends in healthcare, including the shift towards shared or integrated care, in which an individual's healthcare is the responsibility of a team of professionals across all levels of the healthcare system hierarchy. In addition to the requirement for efficient and secure access to the Integrated Electronic Health Record (I-EHR) of a citizen, this necessitates the development and deployment of Regional Health Information Networks (RHINs), synchronous and asynchronous collaboration services, and novel eHealth and mHealth services, facilitated by intelligent sensors, monitoring devices, hand-held or wearable technologies, the Internet and wireless broadband communications. These further require the adoption of an open Reference Architecture and the creation of a scalable Health Information Infrastructure (HII).This paper discusses the challenges encountered in developing and deploying HYGEIAnet, the Regional Health Information Network of Crete, as well as relevant benefits for citizens and health professionals. Furthermore, HYGEIAnet systems and services are presented, with emphasis on the development of the HII and the implementation of the I-EHR service for providing secure, role-based access to validated content by authorized and authenticated users. PMID:15718565

  3. UV extinction and IR emission in diffuse H2 regions

    NASA Technical Reports Server (NTRS)

    Aannestad, Per A.

    1994-01-01

    HII regions occupy a unique position in our understanding of the physical relationships between stars, the interstellar medium, and galactic structure. Observations show a complex interaction between a newly formed hot star and its surroundings. In particular, the ultraviolet radiation from the stars modifies the pre-existing dust, which again affects both the amount of ionizing radiation absorbed by the gas, and the infrared spectrum emitted by the heated dust. The aim of this project was to use UV and far-UV observations to gain information on the nebular dust, and to use this dust to model the far-IR emission, for a consistent picture of a few selected diffuse HII regions. Using archival data from the IUE and Voyager data banks and computed model atmospheres, we have deduced extinction curves for early-types stars. The requisite spectral resolution turned out to be a major task. We have successfully modelled these curves in terms of a multi-component, multi-size distribution of dust grains, and interpret the differences in the curves as primarily due to the presence or non-presence of intermediate size grains (0.01 to 0.04 micron). Much smaller (0.005 micron) grains must also be present. Finally, we have made calculations of the temperature fluctuations and the corresponding infra-red emission in such small grains.

  4. Hubble Space Telescope Hx Imaging of Star-forming Galaxies at z approximately equal to 1-1.5: Evolution in the Size and Luminosity of Giant H II Regions

    NASA Technical Reports Server (NTRS)

    Livermore, R. C.; Jones, T.; Richard, J.; Bower, R. G.; Ellis, R. S.; Swinbank, A. M.; Rigby, J. R.; Smail, Ian; Arribas, S.; Rodriguez-Zaurin, J.; Colina, L.; Ebeling, H.; Crain, R. A.

    2013-01-01

    We present Hubble Space Telescope/Wide Field Camera 3 narrow-band imaging of the Ha emission in a sample of eight gravitationally lensed galaxies at z = 1-1.5. The magnification caused by the foreground clusters enables us to obtain a median source plane spatial resolution of 360 pc, as well as providing magnifications in flux ranging from approximately 10× to approximately 50×. This enables us to identify resolved star-forming HII regions at this epoch and therefore study their Ha luminosity distributions for comparisons with equivalent samples at z approximately 2 and in the local Universe. We find evolution in the both luminosity and surface brightness of HII regions with redshift. The distribution of clump properties can be quantified with an HII region luminosity function, which can be fit by a power law with an exponential break at some cut-off, and we find that the cut-off evolves with redshift. We therefore conclude that 'clumpy' galaxies are seen at high redshift because of the evolution of the cut-off mass; the galaxies themselves follow similar scaling relations to those at z = 0, but their HII regions are larger and brighter and thus appear as clumps which dominate the morphology of the galaxy. A simple theoretical argument based on gas collapsing on scales of the Jeans mass in a marginally unstable disc shows that the clumpy morphologies of high-z galaxies are driven by the competing effects of higher gas fractions causing perturbations on larger scales, partially compensated by higher epicyclic frequencies which stabilize the disc.

  5. Molecular gas associated with IRAS 10361-5830

    NASA Astrophysics Data System (ADS)

    Vazzano, M. M.; Cappa, C. E.; Vasquez, J.; Rubio, M.; Romero, G. A.

    2014-10-01

    Aims: We analyze the distribution of the molecular gas and dust in the molecular clump linked to IRAS 10361-5830, located in the environs of the bubble-shaped Hii region Gum 31 in the Carina region, with the aim of determining the main parameters of the associated material and of investigating the evolutionary state of the young stellar objects identified there. Methods: Using the APEX telescope, we mapped the molecular emission in the J = 3-2 transition of three CO isotopologues, 12CO, 13CO and C18O, over a 1.´5 × 1.´5 region around the IRAS position. We also observed the high-density tracers CS and HCO+ toward the source. The cold- dust distribution was analyzed using submillimeter continuum data at 870 μm obtained with the APEX telescope. Complementary IR and radio data at different wavelengths were used to complete the study of the interstellar medium. Results: The molecular gas distribution reveals a cavity and a shell-like structure of ~0.32 pc in radius centered at the position of the IRAS source, with some young stellar objects projected onto the cavity. The total molecular mass in the shell and the mean H2volume density are ~40 M⊙ and ~(1-2) × 103 cm-3. The cold-dust counterpart of the molecular shell has been detected in the far-IR at 870 μm and in Herschel data at 350 μm. Weak extended emission at 24 μm from warm dust is projected onto the cavity, as well as weak radio continuum emission. Conclusions: A comparison of the distribution of cold and warm dust, and molecular and ionized gas allows us to conclude that a compact Hii region has developed in the molecular clump, indicating that this is an area of recent massive star formation. Probable exciting sources capable of creating the compact Hii region are investigated. The 2MASS source 10380461-5846233 (MSX G286.3773-00.2563) seems to be responsible for the formation of the Hii region. FITS files with datacubes corresponding to 12CO, 13CO, C180 maps are only available at the CDS via anonymous

  6. Study of deuterated molecules in the PDR around the UCHII region Mon R2

    NASA Astrophysics Data System (ADS)

    Treviño-Morales, Sandra P.; Fuente, Asunción; Pilleri, Paolo; Kramer, Carsten; González-García, Manuel; Roueff, Evelyn; Cernicharo, José; Pety, Jerome

    2013-07-01

    Photo-dominated regions (PDRs) are ubiquitous environments where chemistry and heating are driven by UV photons from nearby O & B stars. The massive star forming region Mon R2 is the closest (830 pc) ultracompact (UC) HII region associated with a PDR. We are carrying out a spectral line survey of the PDR associated with Mon R2 using both ground and space based facilities, with the aim of investigating the chemistry of the molecular gas around the UCHII region and the possible variations due to the different local physical conditions. The last year we performed an unbiased spectral survey at 1, 2 and 3 mm, and discovered an unexpectedly rich chemistry. More than thirty different species (including isotopologues and deuterated compounds) were detected. Here we present the results of deuterated molecules, we derive the deuteration in the region and compare it with hot cores, dark clouds, and other PDRs.

  7. Star formation in the inner galaxy: A far-infrared and radio study of two H2 regions

    NASA Technical Reports Server (NTRS)

    Lester, D. F.; Dinerstein, H. L.; Werner, M. W.; Harvey, P. M.; Evans, N. J.; Brown, R. L.

    1985-01-01

    Far-infrared and radio continuum maps have been made of the central 6' of the inner-galaxy HII regions G30.8-0.0 (in the W43 complex) and G25.4-0.2, along with radio and molecular line measurements at selected positions. The purpose of this study is an effort to understand star formation in the molecular ring at 5 kpc in galactic radius. Measurements at several far infrared wavelengths allow the dust temperature structures and total far infrared fluxes to be determined. Comparison of the radio and infrared maps shows a close relationship between the ionized gas and the infrared-emitting material. There is evidence that parts of G30.8 are substantially affected by extinction, even at far-infrared wavelengths. Using radio recombination line and CO line data for G25.4-0.2, the distance ambiguity for this source is resolved. The large distance previously ascribed to the entire complex is found to apply to only one of the two main components. The confusion in distance determination is found to result from an extraordinary near-superposition of two bright HII regions. Using the revised distances of 4.3 kpc for G25.4SE and 12 kpc for G25.4NW, it is found that the latter, which is apparently the fainter of the two sources, is actually the more luminous. The ratio of total luminosity to ionizing luminosity is very similar to that of HII regions in the solar circle. Assuming a coeval population of ionizing stars, a normal initial mass function is indicated.

  8. H II Regions in the Disks of Spiral Galaxies

    NASA Astrophysics Data System (ADS)

    Rozas, M.

    1997-06-01

    The objective of the research presented in the thesis is to use photometrically calibrated high quality images in \\ha\\ of the disks of spiral galaxies to study their global star forming properties. In the first part of the study we catalog and study statistically the \\hii\\ regions in a set of spirals, imaged in \\ha\\ . The observed parameters of each region are its fluxes and diameters, from which we can also derive the mean surface brightness and its internal radial gradient (the latter for the largest most luminous regions). Plotting the luminosity function (LF) for a given galaxy (the number of regions versus \\ha\\ flux) we find a characteristic discontinuity: a peak accompanied by a change in gradient of the function, at a luminosity of 10$^{38.6}$ erg s$^{-1}$ per region. We attribute this to the change from ionization-bounded \\hii\\ regions, at luminosities below the transition, to density-bounded regions above the transition, and explain with a quantitative model based on this assumption why the transition takes place at a well-defined luminosity, and one which varies very little from galaxy to galaxy. In the six galaxies observed and analyzed in this way, the variance is 0.07 mag., making the transition a good prima facie candidate to be a powerful standard candle for accurate extragalactic distance measurements. Confirmation of the nature of the transition is provided by measurements of the internal brightness gradients, which show a jump from a constant value (predicted for ionization bounded regions) below the transition to a larger and increasing value above the transition. The theoretical model which can account for the transition was used to show how the gradients of the LF in the ionization bounded and the density bounded regimes can be used to derive the mass function of the ionizing stars in regions close to the transition luminosity, yielding a mean value for the slope of the MF in the galaxies observed of -2.4; the brightest stars in these

  9. Spitzer Follow-up of HST Observations of Star Formation in H II Regions

    NASA Astrophysics Data System (ADS)

    Hester, Jeff; Bally, John; Desch, Steve; Healy, Kevin; Snider, Keely

    2005-06-01

    Images of regions of star formation taken with HST have given us an extraordinary view of young stellar objects and their natal environments. These views differ tremendously between low-mass YSOs seen in regions of isolated low-mass star formation such as Taurus-Auriga, and the proplyds, EGGs, and other structures seen in regions of massive star formation. While YSOs in Taurus spend their adolescence buried in the dark interiors of molecular clouds, YSOs near massive stars quickly find themselves overrun by ionization fronts and exposed to the intense UV radiation from nearby massive stars. This difference in environment has a profound effect on the way in which the protoplanetary disk around a star evolves -- a fact that is of great importance to us, given the strength of the evidence suggesting that the Sun formed near a massive star. But HST while HST can inform us about the evolution of YSOs in HII region environments once they are overrun by ionization fronts, it cannot show us the birth of the stars themselves. These remain hidden in the dense molecular material beyond the ionized volumes of these regions. Only Spitzer can show us the properties of the YSOs that lie hidden in the dark shadows of HST images of HII regions, and only Spitzer can provide us with information about PDRs, warm dust, and other tracers of the interaction of massive stars with their surroundings. The combination of HST and Spitzer observations of star forming regions is far greater than the sum of its parts. If we are to build a complete picture of low-mass star formation and the evolution of disks near massive stars, we need to combine HST and Spitzer observations of the same regions. In this proposal we request time to obtain both IRAC and MIPS 24 micron images of each HII region that has been observed by HST, but has yet to be observed with Spitzer. Together with previous images obtained from the archives, this will comprise an indispensible data set for testing hypotheses about

  10. Far infrared spectroscopy of star formation regions in M82

    NASA Technical Reports Server (NTRS)

    Duffy, P. B.; Erickson, E. F.; Haas, M. R.; Houck, J. R.

    1986-01-01

    Emission lines of (O III) at 52 microns and 88 microns and of (N III) at 57 microns in the nucleus of the galaxy M82 have been observed from the Kuiper Airborne Observatory with the facility's cooled grating spectrometer. The (N III) line has not been previously detected in any extragalactic source. The fluxes in the lines indicate approx 4 x 10 to the 7th power M of ionized gas and a large population of massive stars (equivalent to 5 x 10 to the 5th power 08.5 stars), sufficient to power the infrared luminosity of the nucleus. We use the 52 to 88 micron line intensity ratio to find an average electron density of 210 + or 75 in the nucleus; this is 10 to 100 times lower than values typically observed in individual compact HII regions in our Galaxy. The relative line strengths of the (O III) and (N III) lines imply an N(++)/O(++) ratio of 0.45 + or - 0.1, significantly lower than is measured by the same method in individual HII regions at similar galactocentric distances (equal to or less than 400 pc) in our Galaxy. This lower N(++)/O(++) ratio may be due to a lower N/O ratio, higher stellar temperatures, or both, in M82. At spectral resolutions of approx. 90 km/s, all three line profiles are similarly asymmetric. They can be well fitted by two Gaussian distributions with widths of approx. 150 km/s and central velocities of approx. 110 and approx. 295 km/s, bracketing the systemic velocity of the nucleus of approx. 210 km/s. Within uncertainties, both the N(++)/O(++) ratio and the electron density are the same for both Gaussian components; this indicates no major large-scale gradient in either quantity within the nucleus.

  11. Observations of the photodissociated HI region that surrounds G213.880-11.837

    NASA Astrophysics Data System (ADS)

    Rodríguez-Rico, C. A.; Gómez, Y.; Garay, G.; Neria, C.; Rodríguez, L. F.; Escalante, V.; Lizano, S.; Lebrón, M.

    2011-10-01

    New observations of the HI 21 cm line toward the cometary HII region G213.880-11.837 are presented. These observations, carried out with an angular resolution of 15'', reveal that the neutral gas in this region is part of an expanding flow. The analysis of the kinematics of the HI gas suggests that the HI gas is undergoing a champagne flow: based on the difference between the radial velocities of the neutral gas in the tail ( 4km s^{-1}) compared to the velocities of the ambient molecular gas ( 11.5 km s^{-1}) and the asymmetry of the HI emission. Besides this photodissociated region, there is only one other reported following an HI champagne flow (G111.61+0.37).

  12. Star Clusters and Associations in the 30 Doradus Region: Tracing more than 25 Myr of Massive Star Formation in a Prototypical Starburst

    NASA Astrophysics Data System (ADS)

    Sabbi, Elena

    2015-08-01

    30 Doradus (a.k.a. Tarantula Nebula) is the closest extragalactic giant HII region. By virtue of its privileged position in the Large Magellanic Cloud 30 Doradus is the only starburst that can be studied down to the sub-solar mass regime.We will discuss the stellar content, the clustering properties, and the temporal and spatial impact of stellar feedback on the lifecycle of stars and clusters in an environment that resembles the extreme conditions found in the starburst knots observed in interacting galaxies in the Local Universe and in the young galaxies at high redshift.

  13. CN emission in Orion. The high density interface between the H II region and the molecular cloud

    NASA Astrophysics Data System (ADS)

    Rodriguez-Franco, A.; Martin-Pintado, J.; Fuente, A.

    1998-01-01

    We present high angular-resolution (12''-26'') large-scale mapping (19'x22') of the Orion A molecular complex in the N=1->0 and N=2->1 rotational transitions of the CN radical. The CN emission is not only confined to the molecular ridge and the optical bar, but it reveals filamentary emission toward the north and southwest of the Trapezium cluster and surrounding M43. The morphology and the kinematics of the CN emission supports the idea that the CN filaments represent the interfaces between the molecular cloud and the major ionization fronts of M42 and M43. The CN lines have been used to estimate the physical conditions of the molecular gas which confines the ionized material in M42 and M43. Surprisingly, the largest line intensity ratios between the N=1->0 and the N=2->1 lines are not observed toward the molecular ridge or the ionization fronts, but towards the Trapezium cluster and in the direction of the ionized gas in M43. Model calculations for the CN excitation implies H_2 densities of ~ 10(5) cm(-3) toward the ridge and ionization fronts and >6*E(6) cm(-3) toward the region surrounding the Trapezium stars. This suggests that for the first time we have detected the confining material behind M42. We estimate that the CN emission arises from a thin ( ~ 1.2*E(15) cm), dense (>6*E(6) cm(-3) ) layer which might have been compressed by the expansion of the HII region. The morphology of the CN emission, dominated by the ionization fronts of the HII regions, indicates that this molecule is an excellent tracer of regions affected by UV radiation. The comparison between the HC_3N and the CN abundance shows dramatic changes (more than 4 orders of magnitude) between the different features observed in OMC1. The [HC_3N]/[CN] abundance ratio varies from values of ~ 10(-3) for the ionization fronts surrounding the HII regions, to 100 for the hot core in Orion. Our data shows that the [HC_3N]/[CN] abundance ratio is an excellent tracer of photon dominated regions (PDRs) and

  14. The distribution of warm gas in the G327.3-0.6 massive star-forming region

    NASA Astrophysics Data System (ADS)

    Leurini, S.; Wyrowski, F.; Herpin, F.; van der Tak, F.; Güsten, R.; van Dishoeck, E. F.

    2013-02-01

    Aims: Most studies of high-mass star formation focus on massive and/or luminous clumps, but the physical properties of their larger scale environment are poorly known. In this work, we aim at characterising the effects of clustered star formation and feedback of massive stars on the surrounding medium by studying the distribution of warm gas through mid-J12CO and 13CO observations. Methods: We present APEX 12CO(6-5), (7-6), 13CO(6-5), (8-7) and HIFI 13CO(10-9) maps of the star forming region G327.36-0.6 with a linear size of ~3 pc × 4 pc. We infer the physical properties of the emitting gas on large scales through a local thermodynamic equilibrium analysis, while we apply a more sophisticated large velocity gradient approach on selected positions. Results: Maps of all lines are dominated in intensity by the photon dominated region around the Hii region G327.3-0.5. Mid-J12CO emission is detected over the whole extent of the maps with excitation temperatures ranging from 20 K up to 80 K in the gas around the Hii region, and H2 column densities from few 1021 cm-2 in the inter-clump gas to 3 × 1022 cm-2 towards the hot core G327.3-0.6. The warm gas (traced by 12 and 13CO(6-5) emission) is only a small percentage (~10%) of the total gas in the infrared dark cloud, while it reaches values up to ~35% of the total gas in the ring surrounding the Hii region. The 12CO ladders are qualitatively compatible with photon dominated region models for high density gas, but the much weaker than predicted 13CO emission suggests that it comes from a large number of clumps along the line of sight. All lines are detected in the inter-clump gas when averaged over a large region with an equivalent radius of 50''(~0.8 pc), implying that the mid-J12CO and 13CO inter-clump emission is due to high density components with low filling factor. Finally, the detection of the 13CO(10-9) line allows to disentangle the effects of gas temperature and gas density on the CO emission, which are

  15. A Multilevel Study of Ammonia in Star Forming Regions - Part Five - the SAGITTARIUS-B2 Region

    NASA Astrophysics Data System (ADS)

    Huttemeister, S.; Wilson, T. L.; Henkel, C.; Mauersberger, R.

    1993-09-01

    NH3 column densities of order 1021 cm-2, the 55 km s-1 SgrB2 (M) and the 65 km s-1 Sgr B2 (N) cores are particularly outstanding. X(NH3) > 10-5, suggesting that a substantial fraction of the nitrogen is in ammonia. The large number of ultracompact HII (UC HII) regions (≥- 19) indicates that the lifetime of a hot core is only ˜10% of the lifetime of an UC HII region.

  16. 2D-Spectroscopy of Two SBS Galaxies with Star Formation Regions

    NASA Astrophysics Data System (ADS)

    Hakopian, Susanna

    2007-08-01

    About 500 SBS-galaxies in the selected fields were classified using a scheme, adapted to slit spectroscopic data obtained for them. Continuing the investigation of these objects as the members of subclasses of objects with nuclear and starforming activity, we are using 2D - spectroscopy, allowing to extend in understanding of the details of morphology, dynamic and kinematic processes and physical nature, by which the differences and similarities in subclasses are caused. This work presents a detailed study of two starforming galaxies in different stages of activity, both consisting of HII-regions, SBS 1202+583 and SBS 1533+574. Observations have been carried out with multipupil spectrographs VAGR at 2.6m and MPFS at 6m telescopes.

  17. 2D spectroscopy of galaxies with star formation regions. Study of SBS 1533+574

    NASA Astrophysics Data System (ADS)

    Hakopian, S. A.; Balayan, S. K.; Dodonov, S. N.; Movsessian, T. A.

    2006-10-01

    A preliminary analysis is given of 2D spectroscopic data on the galaxy SBS 1533+574(AB) obtained using the multipupil spectrographs on the 2.6-m telescope at the BAO (VAGR) and the 6-m telescope at the SAO (MPFS). The two components of the galaxy are star formation regions in different stages. The component SBS 1533+574B is known to be a BCDG. The plots of the intensity distribution of the radiation in the recombination lines of hydrogen and the forbidden lines of gases with a low degree of ionization obtained here make it possible to compare the basic characteristics of the HII-zones and the surrounding shell. The velocity distribution over the field of the galaxy is indicative of a common rotation of the system and of an intrinsic rotation of the components which is more distinct for component B.

  18. Evolution and saturation of Autowaves in photodissociation regions

    NASA Astrophysics Data System (ADS)

    Krasnobaev, K. V.; Tagirova, R. R.; Arafailov, S. I.; Kotova, G. Yu.

    2016-07-01

    The propagation of plane, cylindrical, and spherical waves in a thermally unstable gas-dust medium has been simulated numerically. As applied to the photodissociation regions near O and B stars, we take into account the interaction of ultraviolet radiation with dust grains and large polycyclic aromatic hydrocarbon molecules as well as the gas cooling through the excitation of CII ions and OI atoms and the deexcitation of rotational levels of CO molecules. The instability regions have been determined. The perturbation growth times corresponding to them are ~103-105 yr. We show that wave breaking occurs irrespective of the geometry of motion, while a perturbation in the form of a single pulse gives rise to a sequence of shock waves. The post-shock gas velocity is approximately 0.1-0.5 of the sound velocity, so that the autowaves can contribute noticeably to the observed velocity dispersion of the gas near the boundaries of HII regions. Two-dimensional simulations suggest that the presence of multiple shocks in a thermally unstable medium can accelerate significantly the destruction of preexisting isolated condensations.

  19. Spectroscopy of planetary nebulae in the region of Canis Major

    NASA Astrophysics Data System (ADS)

    Kniazev, A. Yu.

    2012-11-01

    We present the results of a pilot project of spectroscopic observations for planetary nebulae (PNe) and PN candidates in Canis Major, a sky region where the remnant of a disrupted dwarf galaxy cannibalized by the Milky Way may be located. The spectra of seven objects were taken while testing the SALT spectrograph (South African Astronomical Observatory). All elemental abundances have been obtained by the T e method, where the electron temperature is calculated directly using the measured weak auroral [OIII] λ 4363 Å and/or [NII] λ 5755 Å lines. We have measured the intensities of all the detected emission lines and determined the abundances of oxygen and several other elements (N, Ne, S, Cl, C, and He) in all PNe. The radial velocity for one PN has been measured for the first time and the velocities for all of the remaining PNe have been measured with a considerably better accuracy than that of the previously published ones. The elemental abundances for three PNe have been calculated for the first time and the accuracies of determining the abundances for three others have been improved. The measured heavy-element abundance ratios (S/O, Ne/O, Cl/O) are in good agreement with their typical values for HII regions. Among the PNe studied, ESO 428-05 is the first and so far the most likely candidate for belonging to the remnants of a possible dwarf galaxy disrupted by the tidal interaction with the Milky Way.

  20. Herschel far-infrared observations of the Carina Nebula complex - The embedded young stellar and protostellar population

    NASA Astrophysics Data System (ADS)

    Gaczkowski, Benjamin; Preibisch, Thomas; Ratzka, Thorsten; Roccatagliata, Veronica; Ohlendorf, Henrike; Pekruhl, Stephanie

    2013-07-01

    At a distance of 2.3 kpc, the Carina Nebula is the nearest southern region with a large enough massive stellar population to sample the top of the IMF and displays all phenomena of massive star formation. We have performed a 9 square-degree Herschel far-infrared survey of the Carina Nebula complex (CNC) which revealed, for the first time, the very complex and filamentary small-scale structure of the dense clouds. We discovered 642 objects that are independently detected as point-like sources in at least two of the five Herschel bands. About 75% of these are Class 0 protostars with masses between about one and ten solar masses estimated from radiative transfer modeling. Taking the observational limits into account and extrapolating the observed number of Herschel-detected protostars over the stellar initial mass function suggests that the star formation rate of the CNC is about 0.017 solar masses per year. The spatial distribution of the Herschel young stellar objects (YSO) candidates is highly inhomogeneous and does not follow the distribution of cloud mass. Rather, most Herschel YSO candidates are found at the irradiated edges of clouds and pillars. The currently ongoing star formation process forms only low-mass and intermediate-mass stars, but no massive stars. The characteristic spatial configuration of the YSOs provides support to the picture that the formation of this latest stellar generation is triggered by the advancing ionization fronts. Around the bubble-shaped HII region Gum 31 (containing the young stellar cluster NGC 3324) in the north-western part of the CNC we identified 752 candidate YSOs from Spitzer, WISE, and Herschel data and analyzed their spectral energy distributions. Their location in the rim of the bubble is suggestive of their being triggered by a 'collect and collapse' scenario, which agrees well with the observed parameters of the region which we obtained from density and temperature maps from our Herschel data.

  1. Nearby regions of massive star formation

    NASA Astrophysics Data System (ADS)

    Bally, John; Cunningham, Nathaniel; Moeckel, Nickolas; Smith, Nathan

    Observations of the nearest regions of massive star formation such as Orion are reviewed. Early-type stars in the local OB associations, as well as their superbubbles and supershells provide a fossil record of massive star birth in the Solar vicinity over about the last 40 Myr. This record shows that most massive stars are born from dense, high-pressure, hot cores which spawn transient clusters that dissipate into the field soon after formation. A large fraction (15 to 30%) of massive stars are high-velocity runaways moving at more than 20 km s^{-1}. High-mass stars have a larger companion fraction than their lower-mass siblings. The Orion star forming complex contains the nearest site of on-going massive star formation. Studies of the Orion Nebula and the dense molecular cloud core located immediately behind the HII region provide our sharpest view of massive star birth. This region has formed a hierarchy of clusters within clusters. The Trapezium, OMC-1S, and OMC-1 regions represent three closely spaced sub-clusters within the more extended Orion Nebula Cluster. The oldest of these sub-clusters, which consists of the Trapezium stars, has completely emerged from its natal core. The OMC-1S and OMC-1 regions, are still highly embedded and forming clusters of additional moderate and high mass stars. Over a dozen YSOs embedded in OMC-1S are driving jets and outflows, many of which are injecting energy and momentum into the Orion Nebula. Recent proper motion measurements indicate that the Becklin-Neugebauer object is a high-velocity star moving away from the OMC1 core with a velocity of 30 km s^{-1}, making it the youngest high-velocity star known. Source I may be moving in the opposite direction with a velocity of about 12 km s^{-1}. The projected separation between source I and BN was less than few hundred AU about 500 years ago. The spectacular bipolar molecular outflow and system of shock-excited H_2 fingers emerging from OMC-1 has a dynamical age of about 1100

  2. Radial metallicity gradients in spiral galaxies from H II regions and planetary nebulae: probing galactic chemical evolution

    NASA Astrophysics Data System (ADS)

    Stanghellini, Letizia

    2015-08-01

    Radial metallicity gradients, typically observed in spiral galaxies, are excellent constraints for chemical evolution models. The contemporary studies of the two stellar populations, whose progenitors have formed at different times, yield to the chemical and time constraining of the models. In this context, planetary nebula and HII region analysis proved to be ideal two-epochs test populations. We present an assortment of galaxies whose oxygen abundances have been determined both with weak- and strong-line methods, and whose radial metallicity gradients and their evolution in time have disclosed very interesting correlations with the galaxy characteristics. New results from our Gemini/GMOS observations, and a review of the best literature data, set the stage for a better understanding of spiral galaxy evolution.

  3. Carbon gas in SMC low-metallicity star-forming regions

    NASA Astrophysics Data System (ADS)

    Requena-Torres, M. A.; Israel, F. P.; Okada, Y.; Güsten, R.; Stutzki, J.; Risacher, C.; Simon, R.; Zinnecker, H.

    2016-05-01

    This paper presents [ CII ], [ CI ] and CO emission line maps of the star-forming regions N 66, N 25+N 26, and N 88 in the metal-poor Local Group dwarf galaxy SMC. The spatial and velocity structure of the large HII region N 66 reveals an expanding ring of shocked molecular gas centered on the exciting star cluster NGC 346, whereas a more distant dense molecular cloud is being eroded by UV radiation from the same cluster. In the N 25+N 26 and N 88 maps, diffuse [ CII ] emission at a relatively low surface brightness extends well beyond the compact boundaries of the bright emission associated with the HII regions. In all regions, the distribution of this bright [ CII ] emission and the less prominent [ CI ] emission closely follows the outline of the CO complexes, but the intensity of the [ CII ] and [ CI ] emission is generally anticorrelated, which can be understood by the action of photodissociation and photoionization processes. Notwithstanding the overall similarity of CO and [ CII ] maps, the intensity ratio of these lines varies significantly, mostly due to changes in CO brightness. [ CII ] emission line profiles are up to 50% wider in velocity than corresponding CO profiles. A radiative transfer analysis shows that the [ CII ] line is the dominant tracer of (CO-dark) molecular hydrogen in the SMC. CO emission traces only a minor fraction of the total amount of gas. The similarity of the spatial distribution and line profile shape, and the dominance of molecular gas associated with [ CII ] rather than CO emission imply that in the low-metallicity environment of the SMC the small amount of dense molecular gas traced by CO is embedded in the much more extended molecular gas traced only by [ CII ] emission. The contribution from neutral atomic and ionized hydrogen zones is negligible in the star-forming regions observed. The reduced datacubes (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via

  4. Carbon gas in SMC low-metallicity star-forming regions

    NASA Astrophysics Data System (ADS)

    Requena-Torres, M. A.; Israel, F. P.; Okada, Y.; Güsten, R.; Stutzki, J.; Risacher, C.; Simon, R.; Zinnecker, H.

    2016-04-01

    This paper presents [ CII ], [ CI ] and CO emission line maps of the star-forming regions N 66, N 25+N 26, and N 88 in the metal-poor Local Group dwarf galaxy SMC. The spatial and velocity structure of the large HII region N 66 reveals an expanding ring of shocked molecular gas centered on the exciting star cluster NGC 346, whereas a more distant dense molecular cloud is being eroded by UV radiation from the same cluster. In the N 25+N 26 and N 88 maps, diffuse [ CII ] emission at a relatively low surface brightness extends well beyond the compact boundaries of the bright emission associated with the HII regions. In all regions, the distribution of this bright [ CII ] emission and the less prominent [ CI ] emission closely follows the outline of the CO complexes, but the intensity of the [ CII ] and [ CI ] emission is generally anticorrelated, which can be understood by the action of photodissociation and photoionization processes. Notwithstanding the overall similarity of CO and [ CII ] maps, the intensity ratio of these lines varies significantly, mostly due to changes in CO brightness. [ CII ] emission line profiles are up to 50% wider in velocity than corresponding CO profiles. A radiative transfer analysis shows that the [ CII ] line is the dominant tracer of (CO-dark) molecular hydrogen in the SMC. CO emission traces only a minor fraction of the total amount of gas. The similarity of the spatial distribution and line profile shape, and the dominance of molecular gas associated with [ CII ] rather than CO emission imply that in the low-metallicity environment of the SMC the small amount of dense molecular gas traced by CO is embedded in the much more extended molecular gas traced only by [ CII ] emission. The contribution from neutral atomic and ionized hydrogen zones is negligible in the star-forming regions observed. The reduced datacubes (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via

  5. Molecular Outflows in Massive Star Forming Regions

    NASA Astrophysics Data System (ADS)

    Cunningham, Nichol

    2015-11-01

    This thesis presents millimetre continuum and molecular line observations exploring the properties of molecular outflows towards massive star forming regions. Massive stars produce some of the most energetic phenomena in the Galaxy, yet we still do not have a comprehensive understanding of how they actually form. Outflows are known to play a key role in this formation process and their properties, particularly how they change depending on the mass, luminosity and evolution of the driving source can shed light on how massive stars actually form. This thesis presents observations at both high (SMA 3 arcsecond) and low (JCMT 15 arcsecond) spatial resolution of the known jet/outflow tracers, SiO and 12CO, towards a sample massive star forming region drawn from the RMS survey. Furthermore, the presence of infall signatures is explored through observations of HCO+ and H13CO+, and the hot core nature of the regions is probed using tracers such as CH3CN, HC3N and CH3OH. SiO is detected towards approximately 50% of the massive young stellar objects and HII regions in the JCMT sample. The detection of SiO appears to be linked to the age of the RMS source, with the likely younger sources showing a stronger dependence with SiO. The presence of SiO also appears to be linked to the CO velocity, with SiO more efficiently tracing sources with higher velocity dispersions. In the MOPRA observations towards a sample of 33 RMS sources, CH3CN is detected towards 66% of the sources, with the redder likely younger sources having the largest rotational temperatures. This thesis presents the first interferometric SiO (5-4) and 12CO (2-1) observations, taken with the SMA, towards the massive star forming region G203.3166/NGC 2264-C. In this intermediate/massive star forming cluster, SiO is again tracing the youngest sources. Both the SiO and 12CO emission trace two bipolar, high velocity outflows towards the mm brightest, IR-dark, likely youngest sources in this reg! ion. In contrast the IR

  6. The Kinematics, Physical Condition and Magnetic Field of the W3 Irs5 Region

    NASA Astrophysics Data System (ADS)

    Imai, Hiroshi; Sarma, Anuj P.

    2005-01-01

    We have independently investigated water masers associated with the star-forming region W3 IRS5 with the VLBA. Imai et al., found that the maser 3-D motions exhibit outflows, which likely originate from two of the hyper-compact HII regions in this source. Sarma et al., have detected the Zeeman effect in water masers toward W3 IRS5 and measured line-of-sight magnetic field strengths of between 14 and 42 mG. The directions of maser linear polarization are well aligned in the whole maser region and perpendicular to the estimated magnetic field. These polarimetric results are consistent with an hourglass model of the magnetic field in W3 IRS5. Imai et al., also have analyzed the microstructures found in the individual maser features (˜1AU), which exhibit the "fractal fashion" and express turbulence on very small scales. Together, we have demonstrated that observations of water masers enable us to comprehensively enhance our understanding of the early stages of the formation of massive stars in clusters.

  7. The Kinematics, Physical Condition and Magnetic Field of the W3 IRS5 Region

    NASA Astrophysics Data System (ADS)

    Imai, Hiroshi; Sarma, Anuj P.

    We have independently investigated water masers associated with the star-forming region W3 IRS5 with the VLBA. Imai et al., found that the maser 3-D motions exhibit outflows, which likely originate from two of the hyper-compact HII regions in this source. Sarma et al., have detected the Zeeman effect in water masers toward W3 IRS5 and measured line-of-sight magnetic field strengths of between 14 and 42 mG. The directions of maser linear polarization are well aligned in the whole maser region and perpendicular to the estimated magnetic field. These polarimetric results are consistent with an hourglass model of the magnetic field in W3 IRS5. Imai et al., also have analyzed the microstructures found in the individual maser features (˜1AU), which exhibit the "fractal fashion" and express turbulence on very small scales. Together, we have demonstrated that observations of water masers enable us to comprehensively enhance our understanding of the early stages of the formation of massive stars in clusters.

  8. SOFIA/FORCAST Observations of the Arched Filamentary Region in the Galactic Center

    NASA Astrophysics Data System (ADS)

    Hankins, Matthew; Lau, Ryan M.; Morris, Mark; Herter, Terry L.

    2016-06-01

    Abstract: We present 19.7, 25.2, 31.5, and 37.1 μm maps of the Thermal Arched Filament region in the Galactic Center taken with the Faint Object Infrared Camera for the SOFIA Telescope (FORCAST) with an angular resolution of 3.2-3.8". We calculate the integrated infrared luminosity of the Arched Filaments and show that they are consistent with being heated by the nearby Arches cluster. Additionally, using our observations, we infer dust temperatures (75 – 90 K) across the Arched Filaments which are remarkably consistent over large spatial scales (∼ 25 pc). We discuss the possible geometric effects needed to recreate this temperature structure. Additionally, we compare the observed morphology of the Arches in the FORCAST maps with the Paschen-α emission in the region to study what fraction of the infrared emission may be coming from dust in the HII region versus the PDR beneath it. Finally, we use Spitzer/IRAC 8 μm data to look for spatial variations in PAH abundance in the rich UV environment of the young (~2-4 Myr) and massive Arches cluster.

  9. High Circular Polarization in the Star Forming Region NGC 6334: Implications

    NASA Astrophysics Data System (ADS)

    Ménard, François; Chrysostomou, A.; Gledhill, T.; Hough, J. H.; Bailey, J.

    The amino-acids which form the building blocks of biological proteins are all left-handed molecules. By contrast, when these molecules are made in the laboratory equal numbers of the right and left-handed versions are made. This homochirality found in biological material may then well be a prerequisite for the origin of life and a number of processes have been proposed to produce the required enantiomeric excess in prebiotic organic molecules. We report here on the detection of high degrees of circular polarisation in the star forming complex NGC 6334, in the constellation Scorpius. This important finding suggests the widespread nature of a potentially efficient process to produce biomolecules with large chiral excess, namely selective (asymmetric) photolysis by circularly polarised light. The mechanism, well known in the laboratory, was first suggested to take place in a star forming region by Bailey et al. (1998) (Science, 281, 672; and this conference), following our discovery of high degrees of near-infrared circular polarisation in the Orion molecular cloud, OMC-1. NGC 6334 is a giant HII region and molecular cloud similar to Orion. These two detections of large circular polarisation, among the small number of sources surveyed so far, lead us to suggest that selective photolysis by circular polarisation may be quite widespread in massive star formation regions.

  10. The MAGNUM survey: positive feedback in the nuclear region of NGC 5643 suggested by MUSE

    NASA Astrophysics Data System (ADS)

    Cresci, G.; Marconi, A.; Zibetti, S.; Risaliti, G.; Carniani, S.; Mannucci, F.; Gallazzi, A.; Maiolino, R.; Balmaverde, B.; Brusa, M.; Capetti, A.; Cicone, C.; Feruglio, C.; Bland-Hawthorn, J.; Nagao, T.; Oliva, E.; Salvato, M.; Sani, E.; Tozzi, P.; Urrutia, T.; Venturi, G.

    2015-10-01

    We study the ionization and kinematics of the ionized gas in the nuclear region of the barred Seyfert 2 galaxy NGC 5643 using MUSE integral field observations in the framework of the Measuring Active Galactic Nuclei Under MUSE Microscope (MAGNUM) survey. The data were used to identify regions with different ionization conditions and to map the gas density and the dust extinction. We find evidence for a double-sided ionization cone, possibly collimated by a dusty structure surrounding the nucleus. At the center of the ionization cone, outflowing ionized gas is revealed as a blueshifted, asymmetric wing of the [OIII] emission line, up to projected velocity v10 ~ -450 km s-1. The outflow is also seen as a diffuse, low-luminosity radio and X-ray jet, with similar extension. The outflowing material points in the direction of two clumps characterized by prominent line emission with spectra typical of HII regions, located at the edge of the dust lane of the bar. We propose that the star formation in the clumps is due to positive feedback induced by gas compression by the nuclear outflow, providing the first candidate for outflow-induced star formation in a Seyfert-like, radio-quiet AGN. This suggests that positive feedback may be a relevant mechanism in shaping the black hole-host galaxy coevolution. This work is based on observations made at the European Southern Observatory, Paranal, Chile (ESO program 60.A-9339).

  11. Young, Star Forming Regions in NGC 3994 and NGC 3995

    NASA Astrophysics Data System (ADS)

    Weistrop, D.; Eggers, D.; Stone, A.; Nelson, C. H.; Bachilla, R.

    2000-12-01

    NGC 3991, NGC 3994, and NGC 3995 comprise a small group of interacting galaxies. Groundbased images indicate significantly distorted morphology in NGC 3991 and NGC 3995, while NGC 3994 appears to be a normal, inclined spiral. Spectra of NGC 3991 and NGC 3995 have features typical of strong HII regions. NGC 3994 is a LINER. All three galaxies have strong ultraviolet emission and have been observed with IUE (Kinney, et al. 1993). As part of an investigation of star formation in interacting galaxies, we have obtained ultraviolet and visible images of the central regions of NGC 3994 and 3995 with the Space Telescope Imaging Spectrograph on HST. Imaging was obtained in two ultraviolet (FUV-MAMA+F25QTZ, NUV-MAMA+F25CN182) and one visible (CCD+F28X50LP) band. Individual star forming knots (at HST resolution) have been identified in both galaxies. In NGC 3994 star-forming knots are found tracing the spiral arms. Results from ground based spectroscopy indicate nuclear reddening of E(B-V) ~ 0.3- 0.4, suggesting that the lack of UV-bright knots in the center is real and not due to extinction. The knots in NGC 3995 have a distorted, 'hook shaped' distribution. The knots are typically 12 - 45 pc in diameter (FWHM), with observed FUV fluxes of approximately 10-17 to 10-16 ergs cm-2sec-1 Å-1. We compare our imaging and spectroscopy data to current starburst models to constrain knot ages and masses. Knot characteristics as a function of location in the galaxy will also be discussed. This work has been supported in part by NASA, under contract NAS5-31231, and through the Nevada Space Grant Consortium.

  12. A study of the Galactic star forming region IRAS 02593+6016/S 201 in infrared and radio wavelengths

    NASA Astrophysics Data System (ADS)

    Ojha, D. K.; Ghosh, S. K.; Kulkarni, V. K.; Testi, L.; Verma, R. P.; Vig, S.

    2004-03-01

    We present infrared and radio continuum observations of the S 201 star forming region. A massive star cluster is seen, which contains different classes of young stellar objects. The near-infrared colour-colour and colour-magnitude diagrams are studied to determine the nature of these sources. We have discovered knots of molecular hydrogen emission at 2.122 μm in the central region of S 201. These knots are clearly seen along the diffuse emission to the north-west and are probably obscured Herbig-Haro objects. High sensitivity and high resolution radio continuum images from GMRT observations at 610 and 1280 MHz show an arc-shaped structure due to the interaction between the HII region and the adjacent molecular cloud. The ionization front at the interface between the HII region and the molecular cloud is clearly seen comparing the radio, molecular hydrogen and Brγ images. The emission from the carriers of Unidentified Infrared Bands in the mid-infrared 6-9 μm (possibly due to PAHs) as extracted from the Midcourse Space Experiment survey (at 8, 12, 14 and 21 μm) is compared with the radio emission. The HIRES processed IRAS maps at 12, 25, 60 and 100 μm have also been used for comparison. The spatial distribution of the temperature and the optical depth of the warm dust component around the S 201 region has been generated from the mid-infrared images. This paper is based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Centro Galileo Galilei of the CNAA (Consorzio Nazionale per l'Astronomia e l'Astrofisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the

  13. X-ray heating and ionization of broad-emission-line regions in QSO's and active galaxies

    SciTech Connect

    Weisheit, J.C.; Shields, G.A.; Tarter, C.B.

    1980-07-01

    Absorption of x-rays deep within the broad-line emitting clouds in QSO's and the nuclei of active galaxies creates extensive zones of warm (T approx. 10/sup 4/K), partially ionized N/sub e//N approx. 0.1) gas. Because Lyman alpha photons are trapped in these regions, the x-ray energy is efficiently channeled into Balmer lines collisionally excited from the n = 2 level. The HI regions plus the HII regions created by ultraviolet photons illuminating the surfaces of the clouds give rise to integrated L..cap alpha../H..cap alpha.. line emission ratios between 1 and 2. Enhanced MgII line emission from the HI regions gives rise to integrated MgII/H..cap alpha.. ratios near 0.5. The OI line lambda 8446 is efficiently pumped by trapped H..cap alpha.. photons and in the x-ray heated zone an intensity ratio I (lambda 8446)/I(H..cap alpha..) approx. < 0.1 is calculated. All of these computed ratios now are in agreement with observations.

  14. A distância e o conteúdo estelar da região HII gigante G333.1-0.4 - vínculos para a taxa de formação estelar da galáxia

    NASA Astrophysics Data System (ADS)

    Figuerêdo, E.; Damineli, A.; Blum, R.; Conti, P.

    2003-08-01

    Neste trabalho apresentamos imagens de alta resolução angular da região HII gigante G333.1-0.4 obtidas através dos filtros J, H e K no telescópio de 4-m do CTIO. Este trabalho faz parte de um estudo de regiões HII gigantes no infravermelho próximo que tem por objetivo estudar a natureza da formação de estrelas massivas e traçar a estrutura espiral de nossa galáxia. Nossa determinação da distância é baseada no método da paralaxe espectroscópica de estrelas OB localizadas na seqüência principal de idade zero (ZAMS) do Diagrama HR. No caso de G333.1-0.4, a magnitude aparente das estrelas localizadas na ZAMS indica que a distância não pode ser maior do que o limite inferior determinado por técnica rádio (2,8 kpc). Resultados semelhantes foram encontrados para regiões estudadas anteriormente, reforçando a idéia de que a taxa de formação estelar na Via Láctea é menor do que o determinado a partir de dados rádio. Nossos resultados mais recentes sobre o conteúdo estelar de G333.1-0.4 revelaram vários objetos que possuem cores bastante avermelhadas (H-K > 2,0). Nós identificamos estes objetos usando os diagramas cor-cor e cor-magnitude dos aglomerados. Estes objetos apresentam um forte excesso em emissão na banda K e possivelmente se tratam de estrelas do tipo OB envolvidas por um disco/envelope circumestelar espesso. O estudo da função de massa inical desta região, em conjunto com resultados de nossos trabalhos anteriores, aponta para uma IMF independente da posição galática. A contagem de estrelas nos fornece um valor para o número de fótons no contínuo de Lyman que corrobora com a afirmação de que G333.1-0.4 se encontra mais próxima da menor distância determinada por rádio.

  15. Photodissociation Regions

    NASA Technical Reports Server (NTRS)

    Hollenbach, David J.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    The interstellar medium of galaxies is the reservoir out of which stars are born and into which stars inject newly created elements as they age. The physical properties of the interstellar medium are governed in part by the radiation emitted by these stars. Far-ultraviolet (6 eV< hNu < 13.6 eV) photons from massive stars dominate the heating and influence the chemistry of the neutral atomic gas and much of the molecular gas in galaxies. Predominantly neutral regions of the interstellar medium in which the heating and chemistry are regulated by far ultraviolet photons are termed Photodissociation Regions (PDRs). These regions are the origin of most of the non-stellar infrared (IR) and the millimeter and submillimeter CO emission from galaxies. The importance of PDRs has become increasingly apparent with the advances in IR and submillimeter astronomy. The IR emission from PDRs includes fine structure lines of C, C(+) and O; rovibrational lines of H2; rotational lines of CO; broad mid-IR features of polycyclic aromatic hydrocarbons; and a luminous underlying IR continuum from interstellar dust. The transition of H to H2 and C(+) to CO occurs within PDRs. Comparison of observations with theoretical models of PDRs enables one to determine the density and temperature structure, the elemental abundances, the level of ionization, and the radiation field. PDR models have been applied to interstellar clouds near massive stars, planetary nebulae, red giant outflows, photoevaporating planetary disks around newly formed stars, diffuse clouds, the neutral intercloud medium, and molecular clouds in the interstellar radiation field-in summary, much of the interstellar medium in galaxies. Theoretical PDR models explain the observed correlations of the [CII] 158, micrometers with the CO J=1-0 emission, the CO J=1-0 luminosity with the interstellar molecular mass, and the [CII] 158 micrometers plus [OI] 63 micrometers luminosity with the IR continuum luminosity. On a more global

  16. Deep optical survey of the stellar content of Sh2-311 region

    NASA Astrophysics Data System (ADS)

    Yadav, Ram Kesh; Pandey, A. K.; Sharma, Saurabh; Jose, J.; Ogura, K.; Kobayashi, N.; Samal, M. R.; Eswaraiah, C.; Chandola, H. C.

    2015-01-01

    The stellar content in and around Sh2-311 region have been studied using the deep optical observations as well as near-infrared (NIR) data from 2MASS. The region contains three clusters, viz. NGC 2467, Haffner 18 and Haffner 19. We have made an attempt to distinguish the stellar content of these individual regions as well as to re-determine their fundamental parameters such as distance, reddening, age, onto the basis of a new and more extended optical and infrared photometric data set. NGC 2467 and Haffner 19 are found to be located in the Perseus arm at the distances of 5.0 ± 0.4 kpc and 5.7 ± 0.4 kpc, respectively, whereas Haffner 18 is located at the distance of 11.2 ± 1.0 kpc. The clusters NGC 2467 and Haffner 19 might have formed from the same molecular cloud, whereas the cluster Haffner 18 is located in the outer galactic arm, i.e. the Norma-Cygnus arm. We identify 8 class II young stellar objects (YSOs) using the NIR (J-H)/(H-K) two colour diagram. We have estimated the age and mass of the YSOs identified in the present work and those by Snider et al. (2009) using the V/(V-I) colour-magnitude diagram. The estimated ages and mass range of the majority of the YSOs are ≲1 Myr and ∼0.4-3.5 M⊙, respectively, indicating that these sources could be T-Tauri stars or their siblings. Spatial distribution of the YSOs shows that some of the YSOs are distributed around the HII region Sh2-311, suggesting a triggered star formation at its periphery.

  17. Luminosity functions of YSO clusters in Sh-2 255, W3 Main and NGC 7538 star forming regions

    NASA Astrophysics Data System (ADS)

    Ojha, Devendra; Tamura, Motohide

    We have conducted deep near-infrared surveys of the Sh-2 255, W3 Main and NGC 7538 massive star forming regions using simultaneous observations of the JHKs-band with the near-infrared camera SIRIUS on the UH 88-inch telescope and with SUBARU. The near-infrared surveys cover a total area of ~72 square arcmin of three regions with 10-sigma limiting magnitudes of ~19.5, 18.4 and 17.3 in J, H and Ks-band, respectively. Based on the color-color and color-magnitude diagrams and their clustering properties, the candidate young stellar objects are identified and their luminosity functions are constructed in Sh-2 255, W3 Main and NGC 7538. A large number of previously unreported red sources (H-K > 2) have also been detected around these regions. We argue that these red stars are most probably pre-main sequence stars with intrinsic color excesses. The detected young stellar objects show a clear clustering pattern in each region: the Class I-like sources are mostly clustered in molecular cloud region, while the Class II-like sources in or around more evolved optical HII regions. We find that the slopes of the Ks-band luminosity functions of Sh-2 255, W3 Main and NGC 7538 are lower than the typical values reported for the young embedded clusters and their stellar populations are primarily composed of low mass pre-main sequence stars. From the slopes of the Ks-band luminosity functions, we infer that Sh-2 255, W3 Main and NGC 7538 star forming regions are rather young (age <=1 Myr).

  18. Uncovering the monster stars in W49: the most luminous star-forming region in the Milky Way

    NASA Astrophysics Data System (ADS)

    Wu, Shiwei; Bik, Arjan; Henning, Thomas; Pasquali, Anna; Brandner, Wolfgang; Stolte, Andrea

    2015-08-01

    As a part of the LOBSTAR project (Luci OBservations of STARburst regions), which aims at understanding the stellar content of some of the most massive star-forming regions, we present our result on the high-mass stellar content of W49. K-band spectra of the candidate massive stars from VLT/ISAAC and LBT/LUCI provide us with reliable spectral types of dozens of massive stars in this HII region.The first results show that this region hosts several of the most massive stars in our galaxy. Two most brightest stars, one in the core of the central cluster and one in W49 South, were identified as very massive stars (M > 100 M⊙). Their K-band spectra exhibit strong stellar wind features, and they are classified as O2-3.5If* supergiant stars. After comparison to the Geneva evolutionary models, the mass range of W49nr1 was estimated to be between 100 M⊙ and 180 M⊙. Additionally we find 12 O stars with spectral types between O7V and O3V and masses from 25 M⊙ to 125 M⊙, respectively.These results allow us to derive the fundamental parameters of the cluster (mass, age) as well as the total energy output in the form of ionising photons. This will enable us to study the feedback effects of this extreme star forming region in great detail. To our surprise, two young stellar objects with infrared excess feature showing CO emission lines in their spectra are identified. This suggests that circumstellar disks can survive even in this extreme environment. Finally the spatial distribution of the massive stars is analysed to discuss the star formation history and identify potential runaway stars. The extreme properties of this region makes it a good template for more extreme star formation outside our galaxy.

  19. An investigation of the role of the H II region environment on star formation

    NASA Astrophysics Data System (ADS)

    Healy, Kevin Robert

    Data from the Very Large Array, Hubble Space Telescope, and Two Micron All Sky Survey are used to investigate low-mass star formation in the vicinity of HII regions. The gas in H II regions is strongly affected by massive stars through their intense ultraviolet radiation and winds. The H II region environment is expected to affect the process of star formation, from triggering the collapse of cloud cores within the molecular cloud to truncating circumstellar disks in the interior of the H II region. Massive stars end their lives as supernovae, injecting freshly synthesized radionuclides and large amounts of radiant and kinetic energy into their surroundings. Most stars in the Galaxy form in such environments and recent measurements of meteorites demonstrate that the Solar System formed in this setting. The first part of this work describes a Very Large Array survey of water masers in portions of six H II regions. Previous observational studies demonstrate the link between star formation and water maser activity. This study uses high-resolution observations of water masers to pinpoint the sites of star formation in crowded or confused regions. The water maser survey identifies several sites of star formation that are very close to the ionization fronts being driven into the surrounding molecular cloud. The locations and numbers of these water masers indicate that the H II region environment may trigger the formation of protostars, but that the passage of the ionization front may play a role in prematurely terminating infall. Later evolutionary stages of star formation are characterized by infrared emission from circumstellar disks. Near-infrared photometry from the Two Micron All Sky Survey is used to show that stars with circumstellar disks in the star-forming region NGC 6357 cluster near ionization fronts, strongly suggesting exposure to the H II region environment rapidly (~10 4 years) evaporates circumstellar gas and dust. Hubble Space Telescope images in the

  20. Returning "Region" to World Regional Geography

    ERIC Educational Resources Information Center

    Rees, Peter W.; Legates, Margaret

    2013-01-01

    World regional geography textbooks rarely focus on the process of region formation, despite frequent calls to reincorporate a regional approach to teaching global geography. An instructional strategy using problem-based learning in a small honors section of a large world regional geography course is described. Using a hypothetical scenario…

  1. Ionospheric research. [E region, F region, D region

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Progress is reported in the following areas: D-region theory; E and F-region; wave propagation; mass spectrometer measurements; and atmospheric reactions. Various supporting operations are included: design and construction of instrumentation; and programming.

  2. Propiedades físicas del gas en regiones de formación estelar multiples en galaxias BCDs: IIZw33 y Mrk600

    NASA Astrophysics Data System (ADS)

    Campuzano-Castro, F.; Hagele, G.; Cardaci, M.; Bosch, G.; Firpo, V.

    2015-08-01

    In this work we perform a detailed analysis of the spectra of the ionized gas belonging to 9 giant HII regions with violent star formation in two Blue Compact Dwarf galaxies. We have measured a large number of recombination and forbidden lines taking into account the underlying stellar population (defining a pseudo continuum for the hydrogen and helium emission lines). The physical properties of the gas have been estimated using the methodology proposed by our group. For the star forming knots, depending on the data available, we derived: (i) the reddening constant from the hydrogen recombination lines in all the regions, (ii) the electron density in the low excitation zone from the sulphur once ionized [SII]6717 and 6731 emission lines ratio, (iii) the electron temperatures using the auroral lines present in the spectra of several of our regions and applying the direct method or empirical relations and photo ionization models: T([OII]), T([OIII]), T([SII]), T([SIII])], and T([NII]) depending on the quality of the spectra, (iv) ionic abundances of He, O, O, S, S, N, Ne, Ar and Ar in most of the knots, except the last one that could only be measured for one object, (v) the total chemical abundances of O, S, N, Ne and Ar, (vi) the ionization degree from the softness parameter .

  3. Observations of two ``millimetre-only'' cores as candidates for early high-mass star-forming regions

    NASA Astrophysics Data System (ADS)

    Balnozan, Egon; Lo, Nadia; Jones, Paul; Cunningham, Maria; Hill, Tracey; Bronfman, Leonardo

    2013-04-01

    We wish to image at high spectral resolution two “millimetre-only” sources from a subset of 10 identified by Hill et al. (2005) in a 1.2-mm continuum survey. These very bright mm-only sources (also featuring strong NH3 emission) are believed to be excellent candidates for early-stage protostars (C2102-2009JULS) through their characteristic similarity to known massive star-forming sources, despite lacking typical features of massive star formation such as methanol masers and radio continuum. We present evidence of methanol emission in these sources from a recent spectral analysis, along with other molecular species indicative of very early-stage star-formation in cores featuring outflows but devoid of HII regions. High-resolution observations are critical in discriminating between maser and thermal methanol line emission mechanisms that can distinguish between early-stage massive star formation and lower-mass objects. These observations will allow us to quantify the frequency, spatial position and scale of molecular emission to further understanding of the chemistry that distinguishes between low and high-mass star formation, investigate the possible relation between mm-only radio sources and massive protostars, while also gathering data relevant to creating chemical timelines of their early evolution.

  4. Molecular Hydrogen Line Emission from Photodissociation Regions

    NASA Astrophysics Data System (ADS)

    Chrysostomou, Antonio

    1993-01-01

    The work presented in this thesis is dedicated to the study of the physical properties of photodissociation regions (PDRs), the surface layers of molecular clouds which are irradiated by ultraviolet radiation. The structure of PDRs is investigated with the development of an anlytical model which incorporates the essential heating and cooling mechanisms in a PDR. The main parameters in the model are the density and the incident ulttraviolet radiation field (G0) impinging on the surface which dissociates the molecules in the PDR. It is demonstrated that when the ratio (n / G0) is high (> 100 cm-3) the attenuation of ultraviolet photons is dominated by H2 self shielding, which brings the Hi/H2 transition zone close to the surface of the cloud (Av < 1). When the ratio is of order unity then the attenuation of ultraviolet photons is dominated by dust grains in the PDR. In this case, the Hi / H2 transition zone occurs at a depth of Av ~2-3. Images of the PDR in the northern bar of M17 show that there is a spatial coincidence, accurate to ~1 arcsec, of the H2 and 3.28 micron emission regions (the 3.28 micron emission being a tracer of the hot edge of the PDR delineated by the Hii / Hi transition) placing a lower limit to the density in the clumps of 105 cm-3. This coincidence is also observed in other PDR sources (eg. NGC 2023) and can be readily explained if the sources are clumpy. It is not clear in the northern bar of M17, where G0 ~104, whether shielding by dust or H2 molecules is dominated the attenuation of ultraviolet photons. A uniform, high density PDR model is sufficient to reproduce the observed H2 line intensity, however the images clearly reveal structures at the 2 arcsec level suggesting that a clumpy model is a realistic solution. Long slit K band spectroscopy measurements were taken in the northern bar of M17, where up to 16 H2 lines were identified. Analysis of the data suggests that the emission can only be explained if the H2 molecules are being excited

  5. Regional Sustainable Environmental Management

    EPA Science Inventory

    Regional sustainable environmental management is an interdisciplinary effort to develop a sufficient understanding of the interactions between ecosystems, the economy, law, and technology to formulate effective long-term management strategies on a regional scale. Regional sustai...

  6. Comments on Regional Geography.

    ERIC Educational Resources Information Center

    Taaffe, Edward J.

    1985-01-01

    Reasons why regional geography should play a vital role in the development of U.S. geography are discussed. In addition, problems facing regional geographers are examined. A revival of regional geography can be significantly strengthened if there is more effective communication between regional and scientific geographers. (RM)

  7. Guidance and control of HOPE (H-II orbiting plane)

    NASA Astrophysics Data System (ADS)

    Mineno, Hitoshi; Suzuki, Takahiro; Takizawa, Yoshisada

    The National Space Development Agency of Japan (NASDA) has been studying HOPE. Guidance and control technology is one of the most critical technologies to realize HOPE. Studies on guidance and control of HOPE have been done focused on system design and management, navigation, guidance and control, and onboard equipment. The reference configuration and the algorithm of guidance and control system are almost fixed by navigation analyses. We show that the flight path of HOPE can be realized by guidance analyses. A trial model of GCC (Guidance Control Computer), GPSR (GPS Receiver) and MLS (Microwave Landing System) receiver are currently being developed. Several experiments are planned. The MLS flight experiment is explained by an example.

  8. Sulfur-bearing molecules observed in the massive star-forming regions, DR21(OH) and G33.92+0.11

    NASA Astrophysics Data System (ADS)

    Minh, Y. C.

    2016-07-01

    Recent high sensitive and high angular resolution observations are providing unprecedented amount of chemical data, especially, on the massive star-forming regions. It will greatly extend our understandings on the complicated star formation process, if we can digest those huge amount of information. We discuss here on the properties of the sulfurbearing species observed with high angular resolutions toward two massive star-forming regions, DR21(OH) and G33.92+0.11. H2S may not exist as a solid form in the grain mantles, but OCS is believed to be one of major solid sulfur species, as suggested before. In addition, the bipolar-like outflow of the H2CS emission observed in DR21(OH) may suggest that H2CS is also one of solid sulfur species on the grain mantles. Depending on the chemical environment, the competition between hydrogenation and oxidization on the grain surface may lead to formation of specific solid forms to dominate, which could be either H2CS or OCS. SO and SO2 are often observed to be associated with ionized gas, such as the UC HII regions. These species seem to be formed in the high temperature turbulent gas in a later stage of star formation after the hot core phase. Fractional abundances of these sulfur-bearing species appear to be consistent to a certain extent in several star-forming regions. The physical and chemical evolution of massive star formation seems to pass through very similar stages in most star-forming regions. Consequently, it may indicate that there exists a consistent and coherent pattern of processes experienced by the massive star formation, in spite of the large variations in small scale locational differences.

  9. Complex regional pain syndrome

    MedlinePlus

    Complex regional pain syndrome (CRPS) is a chronic pain condition that can affect any area of the ... Bailey A, Audette JF. Complex regional pain syndrome. In: Frontera ... of Physical Medicine and Rehabilitation. 2nd ed. Philadelphia, ...

  10. Utah: Salt Lake Region

    Atmospheric Science Data Center

    2014-05-15

    article title:  Winter and Summer Views of the Salt Lake Region     View Larger Image Magnificent views of the region surrounding Salt Lake City, Utah are captured in these winter and summer images from the ...

  11. New signposts of massive star formation in the S235A-B region

    NASA Astrophysics Data System (ADS)

    Felli, M.; Massi, F.; Robberto, M.; Cesaroni, R.

    2006-07-01

    Aims.We report on new aspects of the star-forming region S235AB revealed through high-resolution observations at radio and mid-infrared wavelengths. Methods: .Using the Very Large Array, we carried out sensitive observations of S235AB in the cm continuum (6, 3.6, 1.3, and 0.7) and in the 22 GHz water maser line. These were complemented with Spitzer Space Telescope Infrared Array Camera archive data to clarify the correspondence between radio and IR sources. We made also use of newly presented data from the Medicina water maser patrol, started in 1987, to study the variability of the water masers found in the region. Results: .S235A is a classical HII region whose structure is now well resolved. To the south, no radio continuum emission is detected either from the compact molecular core or from the jet-like structure observed at 3.3 mm, suggesting emission from dust in both cases. We find two new compact radio continuum sources (VLA-1 and VLA-2) and three separate maser spots. VLA-1 coincides with one of the maser spots and with a previously identified IR source (M 1). VLA-2 lies towards S235B and represents the first radio detection from this peculiar nebula that may represent an ionized wind from a more evolved star. The two other maser spots coincide with an elongated structure previously observed within the molecular core in the C34S line. This structure is perpendicular to a bipolar molecular outflow observed in HCO+(1-0) and may trace the associated equatorial disk. The Spitzer images reveal a red object towards the molecular core. This is the most viable candidate for the embedded source originating the outflow and maser phenomenology. Conclusions: .The picture emerging from these and previous data shows the extreme complexity of a small (≤0.5 pc) star-forming region where widely different stages of stellar evolution are present.

  12. Formation of the twin galactic starburst regions NGC6334 and NGC6357

    NASA Astrophysics Data System (ADS)

    Torii, Kazufumi; Hasegawa, Keisuke; Ohama, Akio; Yamamoto, Hiroaki; Tachihara, Kengo; Fukui, Yasuo

    2015-08-01

    Since 2009, several molecular line observations toward the galactic high-mass star forming regions have indicated that cloud-cloud collisions (CCC) play an important role in forming high-mass stars; for example, super star clusters Westerlund2, NGC3603, and RCW38 (Furukawa et al. 2009; Fukui et al. 2014, 2015) and small galactic HII regions M20 and RCW120 which are each excited by a single O star (Torii et al. 2011, 2015). Using the NANTEN2 4-m telescope situated at Atacama, Chile, we have completed a large-scale molecular line mapping toward young galactic starburst regions NGC6334 and NGC6357. The two regions have several clusetrs which are rich in O stars having 30-100 MSun and are suggested to be physically connected with each other, although they are separated by 100 pc. Our new CO observations show that two molecular cloud complexes are distributed toward NGC6334 and NGC6357 at two different velocities, -3 km/s and -18 km/s. They have filamentary distributions elongated for over 100 pc nearly parallel to the galactic plane. The -3km/s complex apparently shows morphological agreements with the nebulosity in NGC6334 and NGC6357, and the -18km/s complex shows complementary distributions with the -3 km/s complex especially toward the O stars. Furthermore, intermediate velocity features which connect the two complexes are seen toward the same direction. These observational signatures indicate the physical association of the two cloud complexes with NGC6334 and NGC6357. We postulate a scenario that a collision between the two filamentary cloud complexes with a colliding velocity ~15 km/s triggered high-mass star formation in NGC6334 and NGC6357. The timescale of the collision, thus the high-mass star formation, is estimated to be less than 0.5 Myrs, which corresponds to a mass accretion rate up to 2×10-4 MSun/yr. Previous known CCC origin objects are the ones in which high-mass star were formed at a very limited volume less than 1pc3. In contrast, the CCC in NGC

  13. NuSTAR Search for Hard X-ray Emission from the Star Formation Regions in Sh2-104

    NASA Astrophysics Data System (ADS)

    Gotthelf, Eric V.

    2016-04-01

    We present NuSTAR hard X-ray observations of Sh2-104, a compact Hii region containing several young massive stellar clusters (YMSCs). We have detected distinct hard X-ray sources coincident with localized VERITAS TeV emission recently resolved from the giant gamma-ray complex MGRO J2019+37 in the Cygnus region. Faint, diffuse X-ray emission coincident with the eastern YMSC in Sh2-104 is likely the result of colliding winds of component stars. Just outside the radio shell of Sh2-104 lies 3XMM J201744.7+365045 and nearby nebula NuSTAR J201744.3+364812, whose properties are most consistent with extragalactic objects. The combined XMM-Newton and NuSTAR spectrum of 3XMM J201744.7+365045 is well-fit to an absorbed power-law model with NH = (3.1+/-1.0)E22 1/cm^2 and photon index Gamma = 2.1+/-0.1. Based on possible long-term flux variation and lack of detected pulsations (<43% modulation), this object is likely a background AGN rather than a Galactic pulsar. The spectrum of the NuSTAR nebula shows evidence of an emission line at E = 5.6 keV suggesting an optically obscured galaxy cluster at z = 0.19+/-0.02 (d = 800 Mpc) and Lx = 1.2E44 erg/s. Follow-up Chandra observations of Sh2-104 will help identify the nature of the X-ray sources and their relation to MGRO J2019+37.

  14. 2009 Regional Reports

    ERIC Educational Resources Information Center

    Zitzow, Larry; Barbush, Jim; Riese, Gail; Quirk, Robert John; Morris, John P.; Hargrave, Heather

    2010-01-01

    APPA's six regions serve member institutions across the United States and Canada. They function independently from international APPA and offer their own educational programs, annual meetings, publications, and other benefits. Each region also maintains its own set of officers, committees, and activities. Participating in regions and state and…

  15. Learning Regions in Germany

    ERIC Educational Resources Information Center

    Thinesse-Demel, Jutta

    2010-01-01

    In 2000, the German Federal Ministry of Education and Research (BMBF) launched the programme "Learning Regions--Providing Support for Networks'" in cooperation with the Lander. It was co-financed by the European Social Fund (ESF). Some 90 regions were selected and financially supported. After one year, 71 regions continued to build-up their…

  16. Regional flood frequency analysis

    SciTech Connect

    Singh, V.P.

    1987-01-01

    This book, the fourth of a four volume set, contains five sections encompassing major aspects of regional flood frequency analysis. Each section starts usually with an invited state-of-the-art paper followed by contributed papers. The first section provides an assessment of regional flood frequency analysis. Methods for performing regional frequency analysis for ungaged watersheds are presented in Section 2. More discussion on regional frequency analysis is provided in Section 3. Selection and comparison of regional frequency methods are dealt with in Section 4; these are of great interest to the user. Increasing attention is being focused these days on paleohydrologic flood analysis. This topic is covered in Section 5.

  17. Reversed-polarity regions

    NASA Technical Reports Server (NTRS)

    Tang, F.

    1982-01-01

    It is found by a statistical study of 58 reversed-polarity regions (RPRs) covering the 11-year period 1969-1979 that RPRs (1) have a lifespan comparable to normal active regions, (2) do not show a tendency to rotate toward a more normal alignment, and (3) have stable configurations that do not suggest stress due to their anomalous magnetic alignment. As in normal regions, RPR magnetic complexity is found to be the primary factor in flare productivity. Weak-field RPRs produce no flares, and regions with complex spots produce more flares than regions with non-complex spots by a factor of five. The main difference between RPRs and normal regions lies in complex spot frequency, with less that 17% of normal active regions having such spots and fewer than 1.8% having long-lived complex ones, while 41% of RPRs have complex spots and 24% have long-lived complex spots.

  18. Spiral arms and massive star formation: Analysis of the CO face-on pictures of the galaxy

    NASA Technical Reports Server (NTRS)

    Clemens, D. P.; Sanders, D. B.; Scoville, N. Z.

    1986-01-01

    The face-on distribution of molecular gas in the first Galactic quadrant, derived from the Massachusetts-Stony Brook Galactic Plane CO Survey, was compared to the Galactic distribution of giant radio HII regions. The HII regions were found to preferentially select gas regions of higher than average density (more than twice the mean) and showed a strong correlation with the second power of the gas density. Systematic effects were tested with a Monte Carlo simulated HII region distribution and found to be negligible. The 135 HII regions were selected from the radio catalogs of Downes et at. (1980) and Wink et al. (1982). The HII regions were required to be within the CO survey 1 and b limits, within the solar circle, and not part of the 3 kpc expanding arm. The velocities of the HII regions were tabulated by the catalog authors and obvious associations with known objects and H2CO absorptions were used by them to assign distances. The distance assignments were here grouped into two categories; (1) those HII regions with definite distance assignments (85 objects); and (2) those HII regions with less secure distance assignments and those for which no near-far assignment was possible (50 objects).

  19. Norway's Regional College System.

    ERIC Educational Resources Information Center

    Hanisch, Thor Einar

    1981-01-01

    Examines the structure of Norway's short-cycle educational system. Describes how the district colleges function individually as units and collectively within a regional system to provide comprehensive, community-based educational opportunities. Discusses the incorporation of a variety of colleges into the regional system and encourages increased…

  20. REGIONAL EMAP PROPOSALS

    EPA Science Inventory

    The US EPA's Environmental Assessment and Monitoring Program (EMAP) annually funds regional EMAP (REMAP) projects through each of the regions to support the improvement of monitoring activities by the states. The last call for proposals emphasized the need to support biological m...

  1. Ad Hoc Rural Regionalism

    ERIC Educational Resources Information Center

    Hamin, Elisabeth M.; Marcucci, Daniel J.

    2008-01-01

    A new regionalism has been much documented and researched for metropolitan areas; this article documents that there is a new rural regionalism as well. In the United States, these groups appear most likely to emerge in areas that are challenged by outcomes characterizing globalization's effects on the rural condition: namely, exurban or…

  2. Reversed-polarity regions

    NASA Technical Reports Server (NTRS)

    Tang, F.

    1980-01-01

    The 58 RPRS studied have a lifespan comparable to normal active regions and have no tendency to rotate toward a more normal alignment. They seem to have stable configurations with no apparent evidence suggesting stress due to their anomalous magnetic alignment. Magnetic complexity in RPRs is the key to flare productivity just as it is in normal regions - weak field RPRs produced no flares and regions with complex spots produced more flares than regions with noncomplex spots by a factor of 5. The RPRs however, differ from normal regions in the frequency of having complex spots, particularly the long lived complex spots, in them. Less than 17 percent of normal ARs have complex spots; less than 1.8 percent have long lived complex spots. In contrast, 41 percent of RPRs have complex spots and 24 percent have long lived complex spots.

  3. Regional Ocean Data Assimilation

    NASA Astrophysics Data System (ADS)

    Edwards, Christopher A.; Moore, Andrew M.; Hoteit, Ibrahim; Cornuelle, Bruce D.

    2015-01-01

    This article reviews the past 15 years of developments in regional ocean data assimilation. A variety of scientific, management, and safety-related objectives motivate marine scientists to characterize many ocean environments, including coastal regions. As in weather prediction, the accurate representation of physical, chemical, and/or biological properties in the ocean is challenging. Models and observations alone provide imperfect representations of the ocean state, but together they can offer improved estimates. Variational and sequential methods are among the most widely used in regional ocean systems, and there have been exciting recent advances in ensemble and four-dimensional variational approaches. These techniques are increasingly being tested and adapted for biogeochemical applications.

  4. Upper Extremity Regional Anesthesia

    PubMed Central

    Neal, Joseph M.; Gerancher, J.C.; Hebl, James R.; Ilfeld, Brian M.; McCartney, Colin J.L.; Franco, Carlo D.; Hogan, Quinn H.

    2009-01-01

    Brachial plexus blockade is the cornerstone of the peripheral nerve regional anesthesia practice of most anesthesiologists. As part of the American Society of Regional Anesthesia and Pain Medicine’s commitment to providing intensive evidence-based education related to regional anesthesia and analgesia, this article is a complete update of our 2002 comprehensive review of upper extremity anesthesia. The text of the review focuses on (1) pertinent anatomy, (2) approaches to the brachial plexus and techniques that optimize block quality, (4) local anesthetic and adjuvant pharmacology, (5) complications, (6) perioperative issues, and (6) challenges for future research. PMID:19282714

  5. Mercury's South Polar Region

    NASA Video Gallery

    This animation shows 89 wide-angle camera (WAC) images of Mercury’s south polar region acquired by the Mercury Dual Imaging System (MDIS) over one complete Mercury solar day (176 Earth days). Thi...

  6. REGION 9 INDIAN RESERVATIONS

    EPA Science Inventory

    Polygon coverage of all Indian Reservations in US EPA Region 9 (California, Arizona and Nevada). Reservation boundaries are compiled from multiple sources and are derived from several different source scales. Information such as reservation type, primary tribe name and location...

  7. Complex Regional Pain Syndrome

    MedlinePlus

    Complex regional pain syndrome (CRPS) is a chronic pain condition. It causes intense pain, usually in the arms, hands, legs, or feet. ... in skin temperature, color, or texture Intense burning pain Extreme skin sensitivity Swelling and stiffness in affected ...

  8. Regional Health Information Systems

    PubMed Central

    Fuller, Sherrilynne

    1997-01-01

    Abstract In general, there is agreement that robust integrated information systems are the foundation for building successful regional health care delivery systems. Integrated Advanced Information Management System (IAIMS) institutions that, over the years, have developed strategies for creating cohesive institutional information systems and services are finding that IAIMS strategies work well in the even more complex regional environment. The key elements of IAIMS planning are described and lessons learned are discussed in the context of regional health information systems developed. The challenges of aligning the various information agencies and agendas in support of a regional health information system are complex ; however, the potential rewards for health care in quality, efficacy, and cost savings are enormous. PMID:9067887

  9. Regional Instrumentation Centers.

    ERIC Educational Resources Information Center

    Cromie, William J.

    1980-01-01

    Focuses on the activities of regional instrumentation centers that utilize the state-of-the-art instruments and methodology in basic scientific research. The emphasis is on the centers involved in mass spectroscopy, magnetic resonance spectroscopy, lasers, and accelerators. (SA)

  10. On regional geomagnetic charts

    USGS Publications Warehouse

    Alldredge, L.R.

    1987-01-01

    When regional geomagnetic charts for areas roughly the size of the US were compiled by hand, some large local anomalies were displayed in the isomagnetic lines. Since the late 1960s, when the compilation of charts using computers and mathematical models was started, most of the details available in the hand drawn regional charts have been lost. One exception to this is the Canadian magnetic declination chart for 1980. This chart was constructed using a 180 degrees spherical harmonic model. -from Author

  11. Delineation of ecosystem regions

    NASA Astrophysics Data System (ADS)

    Bailey, Robert G.

    1983-07-01

    As a means of developing reliable estimates of ecosystem productivity, ecosystem classification needs to be placed within a geographical framework of regions or zones. This paper explains the basis for the regions delineated on the 1976 map Ecoregions of the United States. Four ecological levels are discussed—domain, division, province, and section—based on climatic and vegetational criteria. Statistical tests are needed to verify and refine map units.

  12. On the Measurement of Elemental Abundance Ratios in Inner Galaxy H II Regions

    NASA Technical Reports Server (NTRS)

    Simpson, Janet P.; Rubin, Robert H.; Colgan, Sean W. J.; Erickson, Edwin F.; Haas, Michael R.

    2004-01-01

    Although abundance gradients in the Milky Way Galaxy certainly exist, details remain uncertain, particularly in the inner Galaxy, where stars and H II regions in the Galactic plane are obscured optically. In this paper we revisit two previously studied, inner Galaxy H II regions: G333.6-0.2 and W43. We observed three new positions in G333.6-0.2 with the Kuiper Airborne Observatory and reobserved the central position with the Infrared Space Observatory's Long Wavelength Spectrometer in far-infrared lines of S++, N++, N+, and O++. We also added the N+ lines at 122 and 205 microns to the suite of lines measured in W43 by Simpson et al.. The measured electron densities range from approx. 40 to over 4000 per cu cm in a single HII region, indicating that abundance analyses must consider density variations, since the critical densities of the observed lines range from 40 to 9000 per cu cm. We propose a method to handle density variations and make new estimates of the S/H and N/H abundance ratios. We find that our sulfur abundance estimates for G333.6-0.2 and W43 agree with the S/H abundance ratios expected for the gradient previously reported by Simpson et al., with the S/H values revised to be smaller owing to changes in collisional excitation cross sections. The estimated N/H, S/H, and N/S ratios are the most reliable because of their small corrections for unseen ionization states (< or approx. 10%). The estimated N/S ratios for the two sources are smaller than what would be calculated from the N/H and S/H ratios in our previous paper. If all low excitation H II regions had similar changes to their N/S ratios as a result of adding measurements of N+ to previous measurements of N++, there would be no or only a very small gradient in N/S. This is interesting because nitrogen is considered to be a secondary element and sulfur is a primary element in galactic chemical evolution calculations. We compute models of the two H II regions to estimate corrections for the other

  13. First Detection of the [O(sub III)] 88 Micrometers Line at High Redshifts: Characterizing the Starburst and Narrow-Line Regions in Extreme Luminosity Systems

    NASA Technical Reports Server (NTRS)

    Ferkinhoff, C.; Hailey-Dunsheath, S.; Nikola, T.; Parshley, S. C.; Stacey, G. J.; Benford, D. J.; Staguhn, J. G.

    2010-01-01

    We have made the first detections of the 88 micrometers [O(sub III)] line from galaxies in the early universe, detecting the line from the lensed active galactic nucleus (AGN)/starburst composite systems APM 08279+5255 at z 3.911 and SMM J02399-0136 at z = 2.8076. The line is exceptionally bright from both systems, with apparent (lensed) luminosities approx.10(exp 11) Solar Luminosity, For APM 08279, the [O(sub III)] line flux can be modeled in a star formation paradigm, with the stellar radiation field dominated by stars with effective temperatures, T(sub eff) > 36,000 K, similar to the starburst found in M82. The model implies approx.35% of the total far-IR luminosity of the system is generated by the starburst, with the remainder arising from dust heated by the AGN. The 881,tm line can also be generated in the narrow-line region of the AGN if gas densities are around a few 1000 cu cm. For SMM J02399, the [O(sub III)] line likely arises from HII regions formed by hot (T(sub eff) > 40,000 K) young stars in a massive starburst that dominates the far-IR luminosity of the system. The present work demonstrates the utility of the [O(sub III)] line for characterizing starbursts and AGN within galaxies in the early universe. These are the first detections of this astrophysically important line from galaxies beyond a redshift of 0.05.s

  14. Northeast Regional Biomass Program

    SciTech Connect

    Lusk, P.D.

    1992-12-01

    The Northeast Regional Biomass Program has been in operation for a period of nine years. During this time, state managed programs and technical programs have been conducted covering a wide range of activities primarily aim at the use and applications of wood as a fuel. These activities include: assessments of available biomass resources; surveys to determine what industries, businesses, institutions, and utility companies use wood and wood waste for fuel; and workshops, seminars, and demonstrations to provide technical assistance. In the Northeast, an estimated 6.2 million tons of wood are used in the commercial and industrial sector, where 12.5 million cords are used for residential heating annually. Of this useage, 1504.7 mw of power has been generated from biomass. The use of wood energy products has had substantial employment and income benefits in the region. Although wood and woodwaste have received primary emphasis in the regional program, the use of municipal solid waste has received increased emphasis as an energy source. The energy contribution of biomass will increase as potentia users become more familiar with existing feedstocks, technologies, and applications. The Northeast Regional Biomass Program is designed to support region-specific to overcome near-term barriers to biomass energy use.

  15. 17 CFR 140.2 - Regional office-regional coordinators.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 17 Commodity and Securities Exchanges 1 2011-04-01 2011-04-01 false Regional office-regional coordinators. 140.2 Section 140.2 Commodity and Securities Exchanges COMMODITY FUTURES TRADING COMMISSION ORGANIZATION, FUNCTIONS, AND PROCEDURES OF THE COMMISSION Organization § 140.2 Regional office—regional coordinators. Each of the Regional...

  16. NV PFA Regional Data

    SciTech Connect

    James Faulds

    2015-10-28

    This project focused on defining geothermal play fairways and development of a detailed geothermal potential map of a large transect across the Great Basin region (96,000 km2), with the primary objective of facilitating discovery of commercial-grade, blind geothermal fields (i.e. systems with no surface hot springs or fumaroles) and thereby accelerating geothermal development in this promising region. Data included in this submission consists of: structural settings (target areas, recency of faulting, slip and dilation potential, slip rates, quality), regional-scale strain rates, earthquake density and magnitude, gravity data, temperature at 3 km depth, permeability models, favorability models, degree of exploration and exploration opportunities, data from springs and wells, transmission lines and wilderness areas, and published maps and theses for the Nevada Play Fairway area.

  17. Stability of regional configurations

    SciTech Connect

    Canavan, G.H.

    1998-08-13

    At moderate force levels the first strike stability index is proportional to the first strike cost, so as the attacker minimizes attack costs, he automatically minimizes stability. Weapons grow rapidly and saturate to levels comparable to the number of value targets held at risk. This growth could appear destabilizing to dominant regional powers, whose response could in turn appear threatening to the major nuclear powers, which could slow or halt efforts towards deep reductions. The fundamental way to alter these pressures appears to be through reducing the likelihood of regional crises by removing these fundamental antagonisms.

  18. Recipe for Regional Development.

    ERIC Educational Resources Information Center

    Baldwin, Fred D.

    1994-01-01

    The Ceramics Corridor has created new jobs in New York's Appalachian region by fostering ceramics research and product development by small private companies. Corridor business incubators offer tenants low overhead costs, fiber-optic connections to Alfred University's mainframe computer, rental of lab space, and use of equipment small companies…

  19. Active region coronal evolution

    NASA Technical Reports Server (NTRS)

    Golub, L.; Noci, G.; Poletto, G.; Vaiana, G. S.

    1982-01-01

    Scaling relations between coronal base pressure and longitudinal photospheric magnetic field strength are tested for the case of a single active region observed for five solar rotations from Skylab. The evolution of measureable quantities, such as coronal thermal energy content, total longitudinal photospheric magnetic flux, region scale size, and peak energy density, is traced throughout the five rotations observed. The theoretically derived scaling law of Golub et al. (1980) is found to provide an acceptable fit to the data throughout the entire evolutionary history of the region from an age of about 3 days to the fully evolved state in which the mature active region merges into the general large-scale structure of the quiet corona. An alternative scaling law obtained by including the results of Galeev et al. (1981), however, is found to provide a somewhat better fit to the data. The study is seen as providing additional justification for the belief that magnetic field-related heating is the operative mechanism in the solar corona.

  20. Multiethnic Societies and Regions.

    ERIC Educational Resources Information Center

    Stanfield, John H., II

    1996-01-01

    Maintains that sociology must reconceptualize the meaning of multiethnic societies and regions and also advance theories about how such social organizations came into being and transform themselves through conflicting and peaceful processes. Briefly reviews traditional approaches and outlines new areas of study. (MJP)

  1. SPARROW REGIONAL NUTRIENT MODEL

    EPA Science Inventory

    This is the second year of funding for the New England SPARROW (Spatially Referenced Regressions on Watershed Attributes) model. Funds in the first year (along with funds allocated for projects supporting Nutrient-Criteria development) were used to analyze regional results ...

  2. MISR Regional SAMUM Products

    Atmospheric Science Data Center

    2016-08-24

    ... three types of MISR Regional products:  Radiance ,  Aerosol , and  Land Surface . Each product summarizes selected parameters ... Radiance/RQI field. Component Global Aerosol Product (CGAS): MI3DAER, MI3MAER, MI3QAER, MI3YAER ...

  3. MISR Regional VBBE Products

    Atmospheric Science Data Center

    2016-08-24

    ... three types of MISR Regional products:  Radiance ,  Aerosol , and  Land Surface . Each product summarizes selected parameters ... Radiance/RQI field. Component Global Aerosol Product (CGAS): MI3DAER, MI3MAER, MI3QAER, MI3YAER ...

  4. Regionalism. Clip and Save.

    ERIC Educational Resources Information Center

    Hubbard, Guy

    2002-01-01

    Focuses on the art movement, called Regionalism, discussing the painters involved and describing the characteristics of the art movement. Provides a set of learning activities and background information on John Steuart Curry. Includes a discussion of Curry's painting, "Tornado Over Kansas," and a reproduction of the painting. (CMK)

  5. Benchmarks: WICHE Region 2012

    ERIC Educational Resources Information Center

    Western Interstate Commission for Higher Education, 2013

    2013-01-01

    Benchmarks: WICHE Region 2012 presents information on the West's progress in improving access to, success in, and financing of higher education. The information is updated annually to monitor change over time and encourage its use as a tool for informed discussion in policy and education communities. To establish a general context for the…

  6. Climatic Concepts and Regions.

    ERIC Educational Resources Information Center

    Thomas, Paul F.

    Designed for students in grades 7 through 12, this teaching unit presents illustrative resource materials depicting concepts related to climate and geographic regions. Emphasis is on giving students an understanding of climatic elements and factors, not as isolated, disjointed entities, but as a dynamic interplay of forces having a very definite…

  7. REGIONAL CONFERENCE SUMMARIES, 1966.

    ERIC Educational Resources Information Center

    Bureau of Adult, Vocational, and Technical Education (DHEW/OE), Washington, DC. Div. of Vocational and Technical Education.

    AN AVERAGE OF 200 TEACHER EDUCATORS, STATE DIRECTORS, LAYMEN, AND REPRESENTATIVES OF VARIOUS AGENCIES ATTENDED EACH OF NINE REGIONAL CONFERENCES CONDUCTED THROUGHOUT THE UNITED STATES TO DISCUSS THE INFLUENCE OF SOCIAL AND ECONOMIC CHANGES AND PROBLEMS IN PLANNING AND CONDUCTING VOCATIONAL AND TECHNICAL EDUCATION PROGRAMS. MAJOR SPEECHES PRESENTED…

  8. Regional Norms for English.

    ERIC Educational Resources Information Center

    Kachru, Braj B.

    The debate continues about regional norms for English usage around the world, although the discussion has become more realistic and less didactic. Educated non-native varieties are increasingly accepted, distinctions are being made between national and international language uses, and localized varieties are no longer considered as necessarily…

  9. Lots of Small Stars Born in Starburst Region

    NASA Astrophysics Data System (ADS)

    1999-10-01

    will quickly affect their environment, but how much? At this moment, nobody knows for sure what determines the actual masses of individual stars that are formed in a very massive and turbulent gas cloud, although some ideas can now be tested with these new observations. The NGC 3603 region The new VLT observations are the key part of a larger research programme that also includes observations of the stellar cluster in the famous Tarantula Nebula in the Large Magellanic Cloud (LMC) with the NICMOS instrument on the Hubble Space Telescope (HST), as well as adaptive optics observations with ground-based telescopes of more quiescent, star-forming regions in the Galaxy. However, the team considered the starburst region NGC 3603 as the best target for this kind of investigation. It is situated in the far southern constellation Carina (The Keel) and can only be observed from the South. Moreover, such a study has to focus on the densest part of the cluster that can only be resolved with a very sensitive infrared (IR) instrument under the best seeing conditions. The VLT ANTU telescope and the multi-mode ISAAC facility are ideally suited for this purpose. NGC 3603 is located in the Carina spiral arm in the Milky Way galaxy at a distance of about 20,000 light-years (6 - 7 kpc). It is the only massive, galactic "HII-region" (so denoted by astronomers because part of its hydrogen is ionized) in which a central cluster of strongly UV-radiating stars of types "O" and "B" that ionize the nebula can be studied at visual and near-infrared wavelengths. This is because the line-of-sight is reasonably free of dust in this direction; the dimming in near-infrared radiation due to intervening matter between the nebula and us is only about a factor of 2 (contrary to 80 in visible light). The total mass of the hot O- and B-stars in NGC 3603 is over 2000 solar masses. Together, the more than fifty heavy and bright O-stars in NGC 3603 have about 100 times the ionizing power of the well

  10. REGIONAL RESEARCH, METHODS, AND SUPPORT

    EPA Science Inventory

    The Human Exposure and Atmospheric Sciences Division (HEASD) has several collaborations with regional partners through the Regional Science Program (RSP) managed by ORD's Office of Science Policy (OSP). These projects resulted from common interests outlined in the Regional Appli...