Science.gov

Sample records for galactic nuclear region

  1. Simulations of Globular Clusters Merging in Galactic Nuclear Regions

    NASA Astrophysics Data System (ADS)

    Miocchi, P.; Dolcetta, R. Capuzzo; Matteo, P. Di

    We present the results of detailed N-body simulations regarding the interaction of four massive globular clusters in the central region of a triaxial galaxy. The systems undergo a full merging event, producing a sort of `Super Star Cluster' (SSC) whose features are close to those of a superposition of the individual initial mergers. In contrast with other similar simulations, the resulting SSC structural parameters are located along the observed scaling relations of globular clusters. These findings seem to support the idea that a massive SSC may have formed in early phases of the mother galaxy evolution and contributed to the growth of a massive nucleus.

  2. UNCOVERING THE DEEPLY EMBEDDED ACTIVE GALACTIC NUCLEUS ACTIVITY IN THE NUCLEAR REGIONS OF THE INTERACTING GALAXY Arp 299

    SciTech Connect

    Alonso-Herrero, A.; Roche, P. F.; Esquej, P.; Colina, L.; González-Martín, O.; Ramos Almeida, C.; Asensio Ramos, A.; Rodríguez Espinosa, J. M.; Alvarez, C.; Pereira-Santaella, M.; Levenson, N. A.; Packham, C.; Mason, R. E.; Aretxaga, I.; Díaz-Santos, T.; Perlman, E.; Telesco, C. M.

    2013-12-10

    We present mid-infrared (MIR) 8-13 μm spectroscopy of the nuclear regions of the interacting galaxy Arp 299 (IC 694+NGC 3690) obtained with CanariCam (CC) on the 10.4 m Gran Telescopio Canarias (GTC). The high angular resolution (∼0.''3-0.''6) of the data allows us to probe nuclear physical scales between 60 and 120 pc, which is a factor of 10 improvement over previous MIR spectroscopic observations of this system. The GTC/CC spectroscopy displays evidence of deeply embedded active galactic nucleus (AGN) activity in both nuclei. The GTC/CC nuclear spectrum of NGC 3690/Arp 299-B1 can be explained as emission from AGN-heated dust in a clumpy torus with both a high covering factor and high extinction along the line of sight. The estimated bolometric luminosity of the AGN in NGC 3690 is 3.2 ± 0.6 × 10{sup 44} erg s{sup –1}. The nuclear GTC/CC spectrum of IC 694/Arp 299-A shows 11.3 μm polycyclic aromatic hydrocarbon emission stemming from a deeply embedded (A{sub V} ∼ 24 mag) region of less than 120 pc in size. There is also a continuum-emitting dust component. If associated with the putative AGN in IC 694, we estimate that it would be approximately five times less luminous than the AGN in NGC 3690. The presence of dual AGN activity makes Arp 299 a good example to study such phenomena in the early coalescence phase of interacting galaxies.

  3. Trajectories of Cepheid variable stars in the Galactic nuclear bulge

    NASA Astrophysics Data System (ADS)

    Matsunaga, Noriyuki

    2012-06-01

    The central region of our Galaxy provides us with a good opportunity to study the evolution of galactic nuclei and bulges because we can observe various phenomena in detail at the proximity of 8 kpc. There is a hierarchical alignment of stellar systems with different sizes; from the extended bulge, the nuclear bulge, down to the compact cluster around the central supermassive blackhole. The nuclear bulge contains stars as young as a few Myr, and even hosts the ongoing star formation. These are in contrast to the more extended bulge which are dominated by old stars, ~10Gyr. It is considered that the star formation in the nuclear bulge is caused by fresh gas provided from the inner disk. In this picture, the nuclear bulge plays an important role as the interface between the gas supplier, the inner disk, and the galactic nucleus. Kinematics of young stars in the nuclear bulge is important to discuss the star forming process and the gas circulation in the Galactic Center. We here propose spectroscopic observations of Cepheid variable stars, ~25 Myr, which we recently discovered in the nuclear bulge. The spectra taken in this proposal will allow timely estimates of the systemic velocities of the variable stars.

  4. The Galactic Center region imaged by VERITAS

    NASA Astrophysics Data System (ADS)

    Beilicke, M.; VERITAS Collaboration

    2012-11-01

    The Galactic Center has long been a region of interest for high-energy and very-high-energy observations. Many potential sources of GeV/TeV γ-ray emission have been suggested, e.g., the accretion of matter onto the black hole, cosmic rays from a nearby supernova remnant, or the annihilation of dark matter particles. The Galactic Center has been detected at MeV/GeV energies by EGRET and recently by Fermi/LAT. At GeV/TeV energies, the Galactic Center was detected by different ground-based Cherenkov telescopes such as CANGAROO, Whipple 10 m, HESS, and MAGIC. We present the results from 15 h of VERITAS observations conducted at large zenith angles, resulting in a >10 standard deviation detection. The combined Fermi/VERITAS results are compared to astrophysical models.

  5. Spatially integrated spectroscopy of Galactic HII regions.

    NASA Astrophysics Data System (ADS)

    Robledo-Rella, V.

    2000-11-01

    We present optical-NIR spatially integrated spectroscopy of 7 Galactic HII regions: Carina, M8, M20, RCW6, RCW60, RCW107 and RCW110/111. The effect of the embedded ionizing stars' spectra on the nebular spectra is studied. The distribution of Balmer Equivalent Widths in the combined spectra (nebular plus stellar) is slightly stepper than in the pure nebular spectra. The comparison of this distribution in Extragalactic HII regions and HII/Starbust galaxies may yield a more accurate determination of the underlaying stellar absorption (or emission!) affecting the observed Balmer lines used to derive extinction and other physical parameters of the emitting regions and associated stellar clusters.

  6. H II REGION DRIVEN GALACTIC BUBBLES AND THEIR RELATIONSHIP TO THE GALACTIC MAGNETIC FIELD

    SciTech Connect

    Pavel, Michael D.; Clemens, D. P. E-mail: clemens@bu.edu

    2012-12-01

    The relative alignments of mid-infrared traced Galactic bubbles are compared to the orientation of the mean Galactic magnetic field in the disk. The orientations of bubbles in the northern Galactic plane were measured and are consistent with random orientations-no preferential alignment with respect to the Galactic disk was found. A subsample of H II region driven Galactic bubbles was identified, and as a single population they show random orientations. When this subsample was further divided into subthermal and suprathermal H II regions, based on hydrogen radio recombination linewidths, the subthermal H II regions showed a marginal deviation from random orientations, but the suprathermal H II regions showed significant alignment with the Galactic plane. The mean orientation of the Galactic disk magnetic field was characterized using new near-infrared starlight polarimetry and the suprathermal H II regions were found to preferentially align with the disk magnetic field. If suprathermal linewidths are associated with younger H II regions, then the evolution of young H II regions is significantly affected by the Galactic magnetic field. As H II regions age, they cease to be strongly linked to the Galactic magnetic field, as surrounding density variations come to dominate their morphological evolution. From the new observations, the ratios of magnetic-to-ram pressures in the expanding ionization fronts were estimated for younger H II regions.

  7. Multiline Study of Galactic Star Forming Regions

    NASA Astrophysics Data System (ADS)

    Mookerjea, B.; Kramer, C.; Jakob, H.; Stutzki, J.

    We present first results of observations with SMART at KOSMA of selected Galactic star forming regions in mid-J (4-3) and (7-6) rotational transitions of CO and the two fine structure transitions of C I at 492 and 810 GHz. The aim of this study is to understand the interplay of the physical and chemical structure of the interstellar matter and the UV radiation field from the stars within the molecular clouds by observing the Photon Dominated Regions (PDRs). During this ongoing observational programme, regions around Orion BN/KL, W3, S106, S140 have been observed. Here we present the first results of observations of the W3 region (Jakob et al. 2002). These observations will be combined with existing observations of the emission due to low-J transitions of CO and other tracers of PDRs. The database of intensities of different lines from each of these regions will be used to derive a self-consistent interpretation using the PDR model developed by Störzer, Stutzki, & Sternberg (1996).

  8. THE GREEN BANK TELESCOPE GALACTIC H II REGION DISCOVERY SURVEY

    SciTech Connect

    Bania, T. M.; Anderson, L. D.; Balser, Dana S.; Rood, R. T.

    2010-08-01

    We discovered a large population of previously unknown Galactic H II regions by using the Green Bank Telescope to detect their hydrogen radio recombination line emission. Since recombination lines are optically thin at 3 cm wavelength, we can detect H II regions across the entire Galactic disk. Our targets were selected based on spatially coincident 24 {mu}m and 21 cm continuum emission. For the Galactic zone -16 {sup 0} {<=} l {<=} 67{sup 0} and |b| {<=} 1{sup 0}, we detected 602 discrete recombination line components from 448 lines of sight, 95% of the sample targets, which more than doubles the number of known H II regions in this part of the Milky Way. We found 25 new first quadrant nebulae with negative LSR velocities, placing them beyond the solar orbit. Because we can detect all nebulae inside the solar orbit that are ionized by O-stars, the Discovery Survey targets, when combined with existing H II region catalogs, give a more accurate census of Galactic H II regions and their properties. The distribution of H II regions across the Galactic disk shows strong, narrow ({approx}1 kpc wide) peaks at Galactic radii of 4.3 and 6.0 kpc. The longitude-velocity distribution of H II regions now gives unambiguous evidence for Galactic structure, including the kinematic signatures of the radial peaks in the spatial distribution, a concentration of nebulae at the end of the Galactic Bar, and nebulae located on the kinematic locus of the 3 Kpc Arm.

  9. The Inner Galactic Bulge: Evidence for a Nuclear Bar?

    NASA Astrophysics Data System (ADS)

    Gerhard, Ortwin; Martinez-Valpuesta, Inma

    2012-01-01

    Recent data from the VVV survey have strengthened evidence for a structural change in the Galactic bulge inward of |l| <= 4°. Here we show with an N-body barred galaxy simulation that a boxy bulge formed through the bar and buckling instabilities effortlessly matches measured bulge longitude profiles for red clump stars. The same simulation snapshot was earlier used to clarify the apparent boxy bulge—long bar dichotomy, for the same orientation and scaling. The change in the slope of the model longitude profiles in the inner few degrees is caused by a transition from highly elongated to more nearly axisymmetric isodensity contours in the inner boxy bulge. This transition is confined to a few degrees from the Galactic plane; thus the change of slope is predicted to disappear at higher Galactic latitudes. We also show that the nuclear star count map derived from this simulation snapshot displays a longitudinal asymmetry similar to that observed in the Two Micron All Sky Survey (2MASS) data, but is less flattened to the Galactic plane than the 2MASS map. These results support the interpretation that the Galactic bulge originated from disk evolution and question the evidence advanced from star count data for the existence of a secondary nuclear bar in the Milky Way.

  10. THE INNER GALACTIC BULGE: EVIDENCE FOR A NUCLEAR BAR?

    SciTech Connect

    Gerhard, Ortwin; Martinez-Valpuesta, Inma

    2012-01-15

    Recent data from the VVV survey have strengthened evidence for a structural change in the Galactic bulge inward of |l| {<=} 4 Degree-Sign . Here we show with an N-body barred galaxy simulation that a boxy bulge formed through the bar and buckling instabilities effortlessly matches measured bulge longitude profiles for red clump stars. The same simulation snapshot was earlier used to clarify the apparent boxy bulge-long bar dichotomy, for the same orientation and scaling. The change in the slope of the model longitude profiles in the inner few degrees is caused by a transition from highly elongated to more nearly axisymmetric isodensity contours in the inner boxy bulge. This transition is confined to a few degrees from the Galactic plane; thus the change of slope is predicted to disappear at higher Galactic latitudes. We also show that the nuclear star count map derived from this simulation snapshot displays a longitudinal asymmetry similar to that observed in the Two Micron All Sky Survey (2MASS) data, but is less flattened to the Galactic plane than the 2MASS map. These results support the interpretation that the Galactic bulge originated from disk evolution and question the evidence advanced from star count data for the existence of a secondary nuclear bar in the Milky Way.

  11. Molecular Lines of 13 Galactic Infrared Bubble Regions

    NASA Astrophysics Data System (ADS)

    Yan, Qing-zeng; Xu, Ye; Zhang, Bo; Lu, Deng-rong; Chen, Xi; Tang, Zheng-hong

    2016-11-01

    We investigated the physical properties of molecular clouds and star formation (SF) processes around infrared bubbles, which are essentially expanding H ii regions. We performed observations of 13 galactic infrared bubble fields containing 18 bubbles. We observed five molecular lines—12CO (J=1\\to 0), 13CO (J=1\\to 0), C18O (J=1\\to 0), HCN (J=1\\to 0), and HCO+ (J=1\\to 0)—and several publicly available surveys were used for comparison: Galactic Legacy Infrared Mid-Plane Survey Extraordinaire, Multiband Imaging Photometer for Spitzer Galactic Plane Survey, APEX Telescope Large Area Survey of the Galaxy, Bolocam Galactic Plane Survey, Very Large Array (VLA) Galactic Plane Survey, Multi-Array Galactic Plane Imaging Survey, and NRAO VLA Sky Survey. We find that these bubbles are generally connected with molecular clouds, most of which are giant. Several bubble regions display velocity gradients and broad-shifted profiles, which could be due to the expansion of bubbles. The masses of molecular clouds within bubbles range from 100 to 19,000 M ⊙, and their dynamic ages are about 0.3–3.7 Myr, which takes into account the internal turbulence pressure of surrounding molecular clouds. Clumps are found in the vicinity of all 18 bubbles, and molecular clouds near four of these bubbles with larger angular sizes show shell-like morphologies, indicating that either collect-and-collapse or radiation-driven implosion processes may have occurred. Due to the contamination of adjacent molecular clouds, only six bubble regions are appropriate to search for outflows, and we find that four have outflow activities. Three bubbles display ultra-compact H ii regions at their borders, and one is probably responsible for its outflow. In total, only six bubbles show SF activities in the vicinity, and we suggest that SF processes might have been triggered.

  12. Infrared diffuse interstellar bands in the Galactic Centre region.

    PubMed

    Geballe, T R; Najarro, F; Figer, D F; Schlegelmilch, B W; de la Fuente, D

    2011-11-02

    The spectrum of any star viewed through a sufficient quantity of diffuse interstellar material reveals a number of absorption features collectively called 'diffuse interstellar bands' (DIBs). The first DIBs were reported about 90  years ago, and currently well over 500 are known. None of them has been convincingly identified with any specific element or molecule, although recent studies suggest that the DIB carriers are polyatomic molecules containing carbon. Most of the DIBs currently known are at visible and very near-infrared wavelengths, with only two previously known at wavelengths beyond one micrometre (10,000 ångströms), the longer of which is at 1.318 micrometres (ref. 6). Here we report 13 diffuse interstellar bands in the 1.5-1.8 micrometre interval on high-extinction sightlines towards stars in the Galactic Centre. We argue that they originate almost entirely in the Galactic Centre region, a considerably warmer and harsher environment than where DIBs have been observed previously. The relative strengths of these DIBs towards the Galactic Centre and the Cygnus OB2 diffuse cloud are consistent with their strengths scaling mainly with the extinction by diffuse material.

  13. The Intermediate-line Region in Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Adhikari, T. P.; Różańska, A.; Czerny, B.; Hryniewicz, K.; Ferland, G. J.

    2016-11-01

    We show that the recently observed suppression of the gap between the broad-line region (BLR) and the narrow-line region (NLR) in some active galactic nuclei (AGNs) can be fully explained by an increase of the gas density in the emitting region. Our model predicts the formation of the intermediate-line region (ILR) that is observed in some Seyfert galaxies by the detection of emission lines with intermediate-velocity FWHM ∼ 700–1200 km s‑1. These lines are believed to be originating from an ILR located somewhere between the BLR and NLR. As was previously proved, the apparent gap is assumed to be caused by the presence of dust beyond the sublimation radius. Our computations with the use of the cloudy photoionization code show that the differences in the shape of the spectral energy distribution from the central region of AGNs do not diminish the apparent gap in the line emission in those objects. A strong discontinuity in the line emission versus radius exists for all lines at the dust sublimation radius. However, increasing the gas density to ∼{10}11.5 cm‑3 at the sublimation radius provides the continuous line emission versus radius and fully explains the recently observed lack of apparent gap in some AGNs. We show that such a high density is consistent with the density of upper layers of an accretion disk atmosphere. Therefore, the upper layers of the disk atmosphere can give rise to the formation of observed emission-line clouds.

  14. Physical conditions in photodissociation regions: Application to galactic nuclei

    NASA Technical Reports Server (NTRS)

    Wolfire, M. G.; Tielens, A. G. G. M.; Hollenbach, David J.

    1990-01-01

    Infrared and sub-millimeter observations are used in a simple procedure to determine average physical properties of the neutral interstellar medium in Galactic photodissociation regions as well as in ensembles of clouds which exist in the nuclei of luminous infrared galaxies. The relevant observations include the Infrared Astronomy Satellite (IRAS) infrared continuum measurements, infrared spectroscopy of the fine-structure lines of SiII 35 microns, OI 63 microns, and CII 158 microns, and the 2.6 mm CO (J=1-0) rotational transition. The diagnostic capabilities of the OI 145 microns line is also addressed. Researchers attribute these emission lines as well as the continuum to the atomic/molecular photodissociation region on the surfaces of molecular clouds which are illuminated by strong ultraviolet fields. They use the theoretical photodissociation region models of Tielens and Hollenbach (1985, Ap. J., 291, 722) to construct simple diagrams which utilize line ratios and line to continuum ratios to determine the average gas density n, the average incident far-ultraviolet flux G sub o, and the temperature of the atomic gas T.

  15. Infrared Spectroscopy of Star Formation in Galactic and Extragalactic Regions

    NASA Technical Reports Server (NTRS)

    Frogel, Jay (Technical Monitor); Smith, Howard A.

    2004-01-01

    In this program we proposed to perform a series of spectroscopic studies, including data analysis and modeling, of star formation regions using an ensemble of archival space-based data from the Infrared Space Observatory's Long Wavelength Spectrometer and Short Wavelength Spectrometer, and to take advantage of other spectroscopic databases including the first results from SIRTF. Our empha- sis has been on star formation in external, bright IR galaxies, but other areas of research have in- cluded young, low or high mass pre-main sequence stars in star formation regions, and the galactic center. The OH lines in the far infrared were proposed as one key focus of this inquiry because the Principal Investigator (H. Smith) had a full set of OH IR lines from IS0 observations. It was planned that during the proposed 2-1/2 year timeframe of the proposal other data (including perhaps from SIRTF) would become available, and we intended to be responsive to these and other such spec- troscopic data sets. Three papers are included:The Infrared Lines of OH: Diagnostics of Molecular Cloud Conditions in Infrared Bright Galaxies; The Far-Infrared Spectrum of Arp 220; andThe Far-Infrared Emission Line and Continuum Spectrum of the Seyfert Galaxy NGC 1068.

  16. Geometry of Broad Line Regions of Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Lü, Xiao-Rong

    2008-02-01

    It has long remained an open question as to the geometry of the broad line region (BLR) in active galactic nuclei (AGNs). The reverberation mapping technique which measures the response of the broad emission lines to the ionizing continuum, when combined with multiwavelength continuum fitted by sophisticated accretion disks, provides a way of probing the BLR geometry. We analyze a sample of 35 AGNs, which have been monitored by the reverberation mapping campaign. In view of energy budget, the reverberation-based BH masses are found to be in agreement with those obtained by accretion disk models in two thirds of the present sample while the reverberation mapping methods underestimate the BH masses in about one third of objects, as also suggested by Collin et al. in a recent work. We point out that there are obviously two kinds of BLR geometry, which are strongly dependent on the Eddington ratio, and separated by the value LBol/LEdd~0.1. These results prefer a scenario of the disk and wind configuration of the BLR and identify the Eddington ratio as the physical driver regulating the wind in the BLR.

  17. Infrared Spectroscopy of Star Formation in Galactic and Extragalactic Regions

    NASA Technical Reports Server (NTRS)

    Smith, Howard A.; Hasan, Hashima (Technical Monitor)

    2003-01-01

    In this program we proposed to perform a series of spectroscopic studies, including data analysis and modeling, of star formation regions using an ensemble of archival space-based data from the Infrared Space Observatory's Long Wavelength Spectrometer and Short Wavelength Spectrometer, and to take advantage of other spectroscopic databases including the first results from SIRTF. Our emphasis has been on star formation in external, bright IR galaxies, but other areas of research have included young, low or high mass pre-main sequence stars in star formation regions, and the galactic center. The OH lines in the far infrared were proposed as one key focus of this inquiry, because the Principal Investigator (H. Smith) had a full set of OH IR lines from IS0 observations. It was planned that during the proposed 2-1/2 year timeframe of the proposal other data (including perhaps from SIRTF) would become available, and we intended to be responsive to these and other such spectroscopic data sets. The program has the following goals: 1) Refine the data analysis of IS0 observations to obtain deeper and better SNR results on selected sources. The IS0 data itself underwent pipeline 10 reductions in early 2001, and the more 'hands-on data reduction packages' have been released. The IS0 Fabry-Perot database is particularly sensitive to noise and can have slight calibration errors, and improvements are anticipated. We plan to build on these deep analysis tools and contribute to their development. Model the atomic and molecular line shapes, in particular the OH lines, using revised montecarlo techniques developed by the Submillimeter Wave Astronomy Satellite (SWAS) team at the Center for Astrophysics. 2) 3) Use newly acquired space-based SIRTF or SOFIA spectroscopic data as they become available, and contribute to these observing programs as appropriate. 4) Attend scientific meetings and workshops. 5) E&PO activities, especially as related to infrared astrophysics and

  18. The Transition between the Inner Disc and the Innermost Galactic Regions

    NASA Astrophysics Data System (ADS)

    Bono, G.; Genovali, K.; Lemasle, B.; Romaniello, M.; Nonino, M.; Bergemann, M.; Buonanno, R.; Fabrizio, M.; François, P.; Inno, L.; Laney, C.; Matsunaga, N.; Pedicelli, S.; Primas, F.; Thévenin, F.

    2015-05-01

    We discuss the iron and the α-element gradients in the Galactic disc and in the innermost Galactic regions (bulge, bar, nuclear bulge). Accurate spectroscopic measurements of young stellar tracers show a well defined iron gradient between the inner and the outer disc. The same outcome applies to light, α, and heavy elements. Moreover, the [α/Fe] ratio attains solar values over a significant fraction of the disc, in the bar and in the nuclear bulge. Thus suggesting that the slopes of iron and α-elements attain quite similar values. There is evidence of a mild enhancement in the outer disc, but this is the consequence of the steady decrease in iron abundance. Current findings do not allow us to constrain whether the chemical enrichment in the nuclear bulge and in the bar is currently driven by bar instabilities. The recent results by the ARGOS spectroscopic survey of intermediate-age stellar tracers (red clump) suggest that the metal-rich stellar components associated with the boxy/peanut bulge show evidence of a mild iron gradient, while the metal-poor component associated with the thick disc/halo shows a flat iron distribution across the bulge. The [α/Fe] ratio of the metal-rich components is slightly enhanced in the bulge, but attains a solar value in the disc. On the other hand, the metal-poor component is α-enhanced both in the bulge and at larger Galactocentric distances. The chemical enrichment history of the bulge supports N-body simulations suggesting that the bulge formed via a bar-forming and bar-buckling instabilities (Ness et al. 2013a,b).

  19. Detection of high energy X-rays from the galactic center region

    NASA Technical Reports Server (NTRS)

    Dennis, B. R.; Beall, J. H.; Cutler, E. P.; Crannell, C. J.; Dolan, J. G.; Frost, K. J.; Orwig, L. E.

    1979-01-01

    Observations of the galactic center region made with the high energy X-ray detector on OSO-8 are discussed. A strong hard X-ray which was detected during these observations from the vicinity of the galactic center are examined. The counting rate spectrum and the photon number spectrum of the flux are determined. Comparisons with the high energy X-ray fluxes observed from sources in the region by others are discussed.

  20. Diffuse galactic light in the 1500-4200 angstrom region

    NASA Technical Reports Server (NTRS)

    Witt, A. N.; Lillie, C. F.

    1972-01-01

    Diffuse galactic light has been observed with the four stellar photometers of the OAO-2 in 29 of Kapteyn's selected areas. The data can be understood in terms of a wavelength dependent albedo of the interstellar grains with a pronounced minimum around 2200 A with a rapid increase towards unity at wavelengths below 2000 A.

  1. Gravitational lensing of wormholes in the galactic halo region

    NASA Astrophysics Data System (ADS)

    Kuhfittig, Peter K. F.

    2014-03-01

    A recent study by Rahaman et al. has shown that the galactic halo possesses the necessary properties for supporting traversable wormholes, based on two observational results, the Navarro-Frenk-White density profile and the observed flat rotation curves of galaxies. Using a method for calculating the deflection angle pioneered by V. Bozza, it is shown that the deflection angle diverges at the throat of the wormhole. The resulting photon sphere has a radius of about 0.40 ly. Given the dark-matter background, detection may be possible from past data using ordinary light.

  2. Statistical properties of dense molecular clouds in the Galactic center region

    NASA Astrophysics Data System (ADS)

    Miyazaki, A.; Tsuboi, M.

    We report physical properties of molecular clouds from the Galactic center r egion survey in CS J = 1-0 with the Nobeyama 45-m telescope (Tsuboi, Handa, an d Ukita, 1996). We identified over 70 molecular cloud cores in the region. We determined the statistical properties such as size-line width and LTE mass -virial theorem mass relations for the clouds. The size-line width relation is obscure in this survey data because of narrow in the radius range of the observed clouds. But the line width of the Galactic center cloud is about fi ve times larger than that of the disk clouds (Solomon et al.1987). Virial th eorem masses of the Galactic center clouds are 1-2 order of magnitude larger than the LTE masses. These are consistent with the results for larger size c louds around the Galactic center from CO J = 2-1 (Oka 1996).

  3. THE NUCLEAR INFRARED EMISSION OF LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Mason, R. E.; Lopez-Rodriguez, E.; Packham, C.; Alonso-Herrero, A.; Elitzur, M.; Aretxaga, I.; Roche, P. F.; Oi, N.

    2012-07-15

    We present high-resolution mid-infrared (MIR) imaging, nuclear spectral energy distributions (SEDs), and archival Spitzer spectra for 22 low-luminosity active galactic nuclei (LLAGNs; L{sub bol} {approx}< 10{sup 42} erg s{sup -1}). Infrared (IR) observations may advance our understanding of the accretion flows in LLAGNs, the fate of the obscuring torus at low accretion rates, and, perhaps, the star formation histories of these objects. However, while comprehensively studied in higher-luminosity Seyferts and quasars, the nuclear IR properties of LLAGNs have not yet been well determined. We separate the present LLAGN sample into three categories depending on their Eddington ratio and radio emission, finding different IR characteristics for each class. (1) At the low-luminosity, low-Eddington-ratio (log L{sub bol}/L{sub Edd} < -4.6) end of the sample, we identify 'host-dominated' galaxies with strong polycyclic aromatic hydrocarbon bands that may indicate active (circum-)nuclear star formation. (2) Some very radio-loud objects are also present at these low Eddington ratios. The IR emission in these nuclei is dominated by synchrotron radiation, and some are likely to be unobscured type 2 AGNs that genuinely lack a broad-line region. (3) At higher Eddington ratios, strong, compact nuclear sources are visible in the MIR images. The nuclear SEDs of these galaxies are diverse; some resemble typical Seyfert nuclei, while others lack a well-defined MIR 'dust bump'. Strong silicate emission is present in many of these objects. We speculate that this, together with high ratios of silicate strength to hydrogen column density, could suggest optically thin dust and low dust-to-gas ratios, in accordance with model predictions that LLAGNs do not host a Seyfert-like obscuring torus. We anticipate that detailed modeling of the new data and SEDs in terms of accretion disk, jet, radiatively inefficient accretion flow, and torus components will provide further insights into the nuclear

  4. Final SAS-2 gamma-ray results on sources in the galactic anticenter region

    NASA Technical Reports Server (NTRS)

    Thompson, D. J.; Fichtel, C. E.; Hartman, R. C.; Kniffen, D. A.; Lamb, R. C.

    1977-01-01

    Final results are presented for SAS-2 observations of high-energy gamma-rays from the galactic anticenter region. Three main gamma-ray features are shown to characterize this region: a localized source associated with the Crab Nebula and its pulsar, another localized source near galactic coordinates 195 deg, +5 deg, and a general enhancement of the diffuse background 10 to 15 deg south of the galactic plane, which is associated with the Gould Belt. For the Crab, it is found that the radiation is mostly pulsed, the pulsed fraction increases with energy, and the intensity of the radiation in the main and interpulse peaks is approximately the same. The other localized source, provisionally designated as gamma 195+5, is found to have a harder spectrum than the Crab but no obvious radio counterpart; emission from an external galaxy is ruled out.

  5. Nuclear gamma rays from Li-7 in the galactic cosmic radiation.

    NASA Technical Reports Server (NTRS)

    Fishman, G. J.; Clayton, D. D.

    1972-01-01

    The observation of a gamma-ray line feature from the direction of the galactic center by Johnson, Harnden, and Haymes is interpreted as the 478-keV nuclear de-excitation of low-energy Li-7 cosmic rays as they inelastically scatter from the interstellar gas. The prediction of an associated line at 432 keV is proposed as a definitive test of this idea.

  6. SAS-2 observations of the galactic gamma radiation from the Vela region

    NASA Technical Reports Server (NTRS)

    Thompson, D. J.; Bignami, G. F.; Fichtel, C. E.; Kniffen, D. A.

    1974-01-01

    Data from a scan of the galactic plane by the SAS-2 high energy gamma ray experiment in the region 250 deg l2 290 deg show a statistically-significant excess over the general radiation from the galactic plane for gamma radiation of energy 100 MeV in the region 260 deg l2 270 deg and -7.5 deg b2 0 deg. If the enhanced gamma radiation results from interactions of cosmic rays with galactic matter, as the energy spectrum suggests, it seems reasonable to associate the enhancement with large scale galactic features, such as spiral arm segments in that direction, or with the region surrounding the Vela supernova remnant, with which PSR 0833-45 is associated. If the excess is attributed to cosmic rays released from this supernova interacting with the interstellar matter in that region, then on the order of 3.10 to the 50th power ergs would be released by that supernova in the form of cosmic rays.

  7. Wormhole solutions for f(G) gravity in galactic halo region

    NASA Astrophysics Data System (ADS)

    Sharif, M.; Ismat Fatima, H.

    2016-04-01

    In this paper, we study static spherically symmetric wormhole solutions in galactic halo region. Two observational results, Navarro-Frenk-White energy density profile in standard cosmological model and the observed flat rotational curves, are used to discuss traversable wormholes supported by galactic halo in modified Gauss-Bonnet gravity. We explore these solutions either by considering a viable f(G) model to construct shape function or by specifying the shape function to deduce f(G) model. We explore energy conditions and find physically acceptable wormhole solutions threaded by normal matter for all values of r. Finally, we investigate stability of the resulting wormhole solutions.

  8. Trigonometric parallaxes to star-forming regions within 4 kpc of the galactic center

    SciTech Connect

    Sanna, A.; Menten, K. M.; Zhang, B.; Sato, M.; Brunthaler, A.; Immer, K.; Reid, M. J.; Dame, T. M.; Moscadelli, L.

    2014-02-01

    We report four trigonometric parallaxes for high-mass star-forming regions within 4 kpc of the Galactic center. These measurements were made with the Very Long Baseline Array as part of the BeSSeL Survey. By associating these sources kinematically with large-scale features in CO and H I longitude-velocity diagrams, we begin to outline some major features of the inner Milky Way: the Connecting arm, the near and far 3 kpc arms, and the Norma arm. The Connecting arm in the first Galactic quadrant lies closer to the Galactic center than the far 3 kpc arm and is offset by the long-bar's major axis near its leading edge, supporting the presence of an inner Lindblad resonance. Assuming the 3 kpc arms are a continuous physical structure, the relative Galactocentric distance of its near and far sides suggests highly elliptical streamlines of gas around the bar(s) and a bar corotation radius, r {sub CR} ≳ 3.6 kpc. At a Galactic longitude near 10° and a heliocentric distance of about 5 kpc, the near 3 kpc arm and the Norma arm intersect on a face-on view of our Galaxy, while passing at different Galactic latitudes. We provide an accurate distance measurement to the W 31 star-forming complex of 4.95{sub −0.43}{sup +0.51} kpc from the Sun, which associates it with a bright CO feature belonging to the near 3 kpc arm.

  9. Evidence for TeV Gamma-Ray Emission from a Region of the Galactic Plane

    SciTech Connect

    Atkins, R.; Gonzalez, M.M.; McEnery, J.E.; Wilson, M.E.; Benbow, W.; Coyne, D.G.; Dorfan, D.E.; Kelley, L.A.; Morales, M.F.; Parkinson, P.M. Saz; Williams, D.A.; Berley, D.; Blaufuss, E.; DeYoung, T.; Goodman, J.A.; Hays, E.; Lansdell, C.P.; Noyes, D.; Smith, A.J.; Sullivan, G.W.

    2005-12-16

    Gamma-ray emission from a narrow band at the galactic equator has previously been detected up to 30 GeV. We report evidence for a TeV gamma-ray signal from a region of the galactic plane by Milagro, a large-field-of-view water Cherenkov detector for extensive air showers. An excess with a significance of 4.5 standard deviations has been observed from the region of galactic longitude l (set-membership sign) (40 deg.,100 deg.) and latitude vertical bar b vertical bar <5 deg. Under the assumption of a simple power law spectrum, with no cutoff in the EGRET-Milagro energy range, the measured integral flux is {phi}{sub {gamma}}(>3.5 TeV)=(6.4{+-}1.4{+-}2.1)x10{sup -11} cm{sup -2} s{sup -1} sr{sup -1}. This flux is consistent with an extrapolation of the EGRET spectrum between 1 and 30 GeV in this galactic region.

  10. Uncovering the Beast: The Galactic Starburst Region W49A

    NASA Astrophysics Data System (ADS)

    Homeier, N.; Alves, J.

    2002-12-01

    We present J, H, and Ks images of an unbiased 5‧ x 5‧ (16 pc x 16 pc) survey of the densest region of the W49 giant molecular cloud. The observations reveal a massive stellar cluster (Cluster 1) about 3 pc East of the well-known Welch ring of ultra-compact H II regions, as well as three smaller clusters associated with compact sources of radio emission. Cluster 1 powers a 6 pc diameter giant H II region seen at both the NIR and radio continuum, and has more than 30 visual magnitudes of internal imhomogeneous extinction, implying that it is still deeply embedded in its parent molecular cloud. The census of massive stars in W49A agrees or slightly overabundant when compared with the number of Lyman continuum photons derived from radio observations. We argue that although the formation of the Welch ring could have been triggered by Cluster 1, the entire W49A starburst region seems to have been multi-seeded instead of resulting from a coherent trigger.

  11. A New Perspective of the Radio Bright Zone at The Galactic Center: Feedback from Nuclear Activities

    NASA Astrophysics Data System (ADS)

    Zhao, Jun-Hui; Morris, Mark R.; Goss, W. M.

    2016-02-01

    New observations of Sgr A have been carried out with the Jansky VLA in the B and C arrays using the broadband (2 GHz) continuum mode at 5.5 GHz. The field of view covers the central 13‧ (30 pc) region of the radio-bright zone at the Galactic center. Using the multi-scale and multi-frequency-synthesis (MS-MFS) algorithms in CASA, we have imaged Sgr A with a resolution of 1″, achieving an rms noise of 8 μJy beam-1, and a dynamic range of 100,000:1. Both previously known and newly identified radio features in this region are revealed, including numerous filamentary sources. The radio continuum image is compared with Chandra X-ray images, with a CN emission-line image obtained with the Submillimeter Array and with detailed Paschen-α images obtained with Hubble Space Telescope/NICMOS. We discuss several prominent features in the radio image. The “Sgr A west Wings” extend 2‧ (5 pc) from the NW and SE tips of the Sgr A west H ii region (the “Mini-spiral”) to positions located 2.9 and 2.4 arcmin to the northwest and southeast of Sgr A*, respectively. The NW wing, along with several other prominent features, including the previously identified “NW Streamers,” form an elongated radio lobe (NW lobe), oriented nearly perpendicular to the Galactic plane. This radio lobe, with a size of 6.‧3 × 3.‧2 (14.4 pc × 7.3 pc), has a known X-ray counterpart. In the outer region of the NW lobe, a row of three thermally emitting rings is observed. A field containing numerous amorphous radio blobs extends for a distance of ˜2 arcmin beyond the tip of the SE wing; these newly recognized features coincide with the SE X-ray lobe. Most of the amorphous radio blobs in the NW and SE lobes have Paschen-α counterparts. We propose that they have been produced by shock interaction of ambient gas concentrations with a collimated nuclear wind or an outflow that originated from within the circumnuclear disk (CND). We also discuss the possibility that the ionized wind or

  12. DO MOST ACTIVE GALACTIC NUCLEI LIVE IN HIGH STAR FORMATION NUCLEAR CUSPS?

    SciTech Connect

    Mushotzky, Richard F.; Shimizu, T. Taro; Meléndez, Marcio; Koss, Michael

    2014-02-01

    We present early results of the Herschel PACS (70 and 160 μm) and SPIRE (250, 350, and 500 μm) survey of 313 low redshift (z < 0.05), ultra-hard X-ray (14-195 keV) selected active galactic nuclei (AGNs) from the 58 month Swift/Burst Alert Telescope catalog. Selection of AGNs from ultra-hard X-rays avoids bias from obscuration, providing a complete sample of AGNs to study the connection between nuclear activity and star formation in host galaxies. With the high angular resolution of PACS, we find that >35% and >20% of the sources are ''point-like'' at 70 and 160 μm respectively and many more have their flux dominated by a point source located at the nucleus. The inferred star formation rates (SFRs) of 0.1-100 M {sub ☉} yr{sup –1} using the 70 and 160 μm flux densities as SFR indicators are consistent with those inferred from Spitzer Ne II fluxes, but we find that 11.25 μm polycyclic aromatic hydrocarbon data give ∼3× lower SFR. Using GALFIT to measure the size of the far-infrared emitting regions, we determined the SFR surface density (M {sub ☉} yr{sup –1} kpc{sup –2}) for our sample, finding that a significant fraction of these sources exceed the threshold for star formation driven winds (0.1 M {sub ☉} yr{sup –1} kpc{sup –2})

  13. Mapping Galactic 60Fe Synthesis in Cen CIR Region

    NASA Technical Reports Server (NTRS)

    Woosley, Stanford

    2005-01-01

    This included a 1 year no cost time extension. The grant was for research into the origin of radioactive 60Fe, whose detection was a mission goal for INTEGRAL and RHESSI. During the grant period, both missions ultimately discovered gamma-line emission from this long lived radioactivity at precisely the value that had been predicted years before by Timmes and Woosley (ApJ, 449,204 (1995)). Unfortunately, using "revised" stellar models and cross sections Rauscher et a1 (ApJ, 576, 323 (2002)), had meanwhile predicted a much larger value. During the grant period, Dieter Hartmann (PI on the complementary grant at Clemson) and Woosley corresponded on this discrepancy and Hartmann visited Santa Cruz (November 20 - 28,2004). All of the grant funds in NAG513659 paid for the expenses of that visit. Subsequently, partly motivated by conversations with Hartmann and Diehl, Woosley re-investigated the production of 60Fe and 26A1 in massive stars from 12 - 120 solar masses, with an eye towards determining the relevant, uncertain physics. The chief changes in Rauscher et a1 were "new" Hauser Feshbach cross sections for 59,60Fe(ng) and 26Al(np)26Mg. The latter has an experimental evaluation which was actually better represented in the study of Timmes and Woosley. The iron (ng) cross sections are from theory and the Timmes and Woosley values were just as reliable as those from Rauscher. Experiments need to be done to resolve who is right. In addition uncertainties in stellar winds, opacities and the IMF were explored. The bottom line is that the value predicted by Timmes and Woosley could well be the correct one, but the experimental error bar is larger than was realized. At least half of the uncertainty is nuclear cross sections that can, and should be measured in the laboratory.

  14. Re-analysis of the Radio Luminosity Function of Galactic H II Regions

    NASA Astrophysics Data System (ADS)

    Paladini, R.; De Zotti, G.; Noriega-Crespo, A.; Carey, S. J.

    2009-09-01

    We have re-analyzed continuum and recombination lines radio data available in the literature in order to derive the luminosity function (LF) of Galactic H II regions. The study is performed by considering the first and fourth Galactic quadrants independently. We estimate the completeness level of the sample in the fourth quadrant at 5 Jy, and the one in the first quadrant at 2 Jy. We show that the two samples (fourth or first quadrant) include, as well as giant and supergiant H II regions, a significant number of subgiant sources. The LF is obtained, in each Galactic quadrant, with a generalized Schmidt's estimator using an effective volume derived from the observed spatial distribution of the considered H II regions. The re-analysis also takes advantage of recently published ancillary absorption data allowing to solve the distance ambiguity for several objects. A single power-law fit to the LFs retrieves a slope equal to -2.23 ± 0.07 (fourth quadrant) and to -1.85 ± 0.11 (first quadrant). We also find marginal evidence of a luminosity break at L knee = 1023.45 erg s-1 Hz-1 for the LF in the fourth quadrant. We convert radio luminosities into equivalent Hα and Lyman continuum luminosities to facilitate comparisons with extragalactic studies. We obtain an average total H II regions Lyman continuum luminosity of 0.89 ± 0.23 × 1053 s-1, corresponding to 30% of the total ionizing luminosity of the Galaxy.

  15. Final SAS-2 gamma ray results on sources in the galactic anticenter region

    NASA Technical Reports Server (NTRS)

    Thompson, D. J.; Fichtel, C. E.; Hartman, R. C.; Kniffen, D. A.; Lamb, R. C.

    1976-01-01

    Analysis of SAS-2 high energy Gamma ray data from the direction of the galactic anticenter shows that this region is characterized by: a diffuse emission from the galactic plane which has a maximum along b=0 deg and an enhancement toward negative latitudes associated with Gould's Belt, a strong point source in the direction of the Crab nebula, and a second intense localized source near galactic coordinates 195 deg, +5 deg. Gamma ray emission from the Crab source is dominated by a pulsed flux from PSR 0531+21. The total flux above 100MeV is 3.7 + or - 0.8 million/sq cm s. The source near 195 deg, + 5 deg has a flux above 100 MeV of 4.3 + or - 0.9 million/sq cm s. Its spectrum appears flatter than that of the Crab. The diffuse galactic plane emission at negative lattitudes shows a general correlation with the local matter distribution associated with Gould's Belt. The calculated Gamma ray intensity agrees well with the SAS-2 observations.

  16. Very-high Energy Observations of the Galactic Center Region by VERITAS in 2010-2012

    NASA Astrophysics Data System (ADS)

    Archer, A.; Barnacka, A.; Beilicke, M.; Benbow, W.; Berger, K.; Bird, R.; Biteau, J.; Buckley, J. H.; Bugaev, V.; Byrum, K.; Cardenzana, J. V.; Cerruti, M.; Chen, W.; Chen, X.; Ciupik, L.; Connolly, M. P.; Cui, W.; Dickinson, H. J.; Dumm, J.; Eisch, J. D.; Falcone, A.; Federici, S.; Feng, Q.; Finley, J. P.; Fleischhack, H.; Fortson, L.; Furniss, A.; Galante, N.; Griffin, S.; Griffiths, S. T.; Grube, J.; Gyuk, G.; Håkansson, N.; Hanna, D.; Holder, J.; Hughes, G.; Johnson, C. A.; Kaaret, P.; Kar, P.; Kertzman, M.; Khassen, Y.; Kieda, D.; Krawczynski, H.; Kumar, S.; Lang, M. J.; Maier, G.; McArthur, S.; McCann, A.; Meagher, K.; Moriarty, P.; Mukherjee, R.; Nieto, D.; O'Faoláin de Bhróithe, A.; Ong, R. A.; Otte, A. N.; Park, N.; Perkins, J. S.; Pohl, M.; Popkow, A.; Prokoph, H.; Pueschel, E.; Quinn, J.; Ragan, K.; Rajotte, J.; Reyes, L. C.; Reynolds, P. T.; Richards, G. T.; Roache, E.; Sembroski, G. H.; Shahinyan, K.; Smith, A. W.; Staszak, D.; Telezhinsky, I.; Tucci, J. V.; Tyler, J.; Varlotta, A.; Vincent, S.; Wakely, S. P.; Weinstein, A.; Welsing, R.; Wilhelm, A.; Williams, D. A.; Zajczyk, A.; Zitzer, B.

    2014-08-01

    The Galactic center is an interesting region for high-energy (0.1-100 GeV) and very-high-energy (E > 100 GeV) γ-ray observations. Potential sources of GeV/TeV γ-ray emission have been suggested, e.g., the accretion of matter onto the supermassive black hole, cosmic rays from a nearby supernova remnant (e.g., Sgr A East), particle acceleration in a plerion, or the annihilation of dark matter particles. The Galactic center has been detected by EGRET and by Fermi/LAT in the MeV/GeV energy band. At TeV energies, the Galactic center was detected with moderate significance by the CANGAROO and Whipple 10 m telescopes and with high significance by H.E.S.S., MAGIC, and VERITAS. We present the results from three years of VERITAS observations conducted at large zenith angles resulting in a detection of the Galactic center on the level of 18 standard deviations at energies above ~2.5 TeV. The energy spectrum is derived and is found to be compatible with hadronic, leptonic, and hybrid emission models discussed in the literature. Future, more detailed measurements of the high-energy cutoff and better constraints on the high-energy flux variability will help to refine and/or disentangle the individual models.

  17. THE STAR-FORMATION RELATION FOR REGIONS IN THE GALACTIC PLANE: THE EFFECT OF SPATIAL RESOLUTION

    SciTech Connect

    Vutisalchavakul, Nalin; Evans II, Neal J.; Battersby, Cara

    2014-12-20

    We examined the relations between molecular gas surface density and star-formation rate surface density in an 11 deg{sup 2} region of the Galactic plane. Dust continua at 1.1 mm from the Bolocam Galactic Plane Survey and 22 μm emission from the Wide-field Infrared Survey Explorer (WISE) all-sky survey were used as tracers of molecular gas and the star-formation rate, respectively, across the Galactic longitude of 31.5 ≥ l ≥ 20.5 and Galactic latitude of 0.5 ≥ b ≥ –0.5. The relation was studied over a range of resolutions from 33'' to 20' by convolving images to larger scales. The pixel-by-pixel correlation between 1.1 mm and 22 μm increases rapidly at small scales and levels off at the scale of 5'-8'. We studied the star-formation relation based on a pixel-by-pixel analysis and on an analysis of the 1.1 mm and 22 μm peaks. The star-formation relation was found to be nearly linear with no significant changes in the form of the relation across all spatial scales, and it lies above the extragalactic relation from Kennicutt. The average gas-depletion time is ≈200 Myr and does not change significantly at different scales, but the scatter in the depletion time decreases as the scale increases.

  18. Very-high energy observations of the galactic center region by VERITAS in 2010-2012

    SciTech Connect

    Archer, A.; Beilicke, M.; Buckley, J. H.; Bugaev, V.; Chen, W.; Barnacka, A.; Benbow, W.; Cerruti, M.; Berger, K.; Bird, R.; Biteau, J.; Byrum, K.; Cardenzana, J. V; Dickinson, H. J.; Eisch, J. D.; Chen, X.; Ciupik, L.; Connolly, M. P.; Cui, W.; Dumm, J.; and others

    2014-08-01

    The Galactic center is an interesting region for high-energy (0.1-100 GeV) and very-high-energy (E > 100 GeV) γ-ray observations. Potential sources of GeV/TeV γ-ray emission have been suggested, e.g., the accretion of matter onto the supermassive black hole, cosmic rays from a nearby supernova remnant (e.g., Sgr A East), particle acceleration in a plerion, or the annihilation of dark matter particles. The Galactic center has been detected by EGRET and by Fermi/LAT in the MeV/GeV energy band. At TeV energies, the Galactic center was detected with moderate significance by the CANGAROO and Whipple 10 m telescopes and with high significance by H.E.S.S., MAGIC, and VERITAS. We present the results from three years of VERITAS observations conducted at large zenith angles resulting in a detection of the Galactic center on the level of 18 standard deviations at energies above ∼2.5 TeV. The energy spectrum is derived and is found to be compatible with hadronic, leptonic, and hybrid emission models discussed in the literature. Future, more detailed measurements of the high-energy cutoff and better constraints on the high-energy flux variability will help to refine and/or disentangle the individual models.

  19. Distribution of cosmic gamma rays in the galactic anticenter region as observed by SAS-2

    NASA Technical Reports Server (NTRS)

    Kniffen, D. A.; Fichtel, C. E.; Hartman, R. C.; Thompson, D. J.; Ozel, M. E.; Tumer, T.; Bignami, G. F.; Ogelman, H.

    1975-01-01

    The high energy (above 35 MeV) gamma ray telescope flown on the second Small Astronomy Satellite has collected over one thousand gamma rays from the direction of the galactic anticenter. In addition to the diffuse galactic emission the distribution indicates a strong pulsed contribution from the Crab nebula with the same period and phase as the NP0532 pulsar. There also seems to be an excess in the direction of (gal. long. ? 195 deg; gal. lat ? +5 deg) where there is a region containing old supernova remnants. Search for gamma ray pulsations from other pulsars in the region do not show any statistically significant signal. The general intensity distribution of the gamma rays away from the plane appear to be similar to nonthermal radio emission brightness contours.

  20. Molecular gas in the Galactic center region. III. Probing shocks in molecular cores

    NASA Astrophysics Data System (ADS)

    Huettemeister, S.; Dahmen, G.; Mauersberger, R.; Henkel, C.; Wilson, T. L.; Martin-Pintado, J.

    1998-06-01

    Multiline observations of C(18) O and SiO isotopomers toward 33 molecular peaks in the Galactic center region, taken at the SEST, JCMT and HHT telescopes, are presented. The C(18) O presumably traces the total H_2 column density, while the SiO traces gas affected by shocks and high temperature chemistry. The J =2-> 1 line of SiO is seen only in few regions of the Galactic disk. This line is easily detected in all Galactic center sources observed. A comparison of the strength of the rare isotopomers (29) SiO and (30) SiO to the strength of the main isotopomer (28) SiO implies that the J = 2 -> 1 transition of (28) SiO is optically thick. The (29) Si/(30) Si isotope ratio of 1.6 in the Galactic center clouds is consistent with the terrestrial value. Large Velocity Gradient models show that the dense component (n_H_2 >= 10(4) \\percc) in typical molecular cores in the Galactic center is cool (\\TKIN ~ 25 K), contrary to what is usually found in Giant Molecular Clouds in the disk, where the densest cores are the hottest. High kinetic temperatures, > 100 K, known to exist from NH_3 studies, are only present at lower gas densities of a few 10(3) cm(-3) , where SiO is highly subthermally excited. Assuming that \\CEIO\\ traces all of the molecular gas, it is found that in all cases but one, SiO emission is compatible with arising in gas at higher density that is (presently) relatively cool. The relative abundance of SiO is typically 10(-9) , but differs significantly between individual sources. It shows a dependence on the position of the source within the Galactic center region. High abundances are found in those regions for which bar potential models predict a high likelihood for cloud-cloud collisions. These results can be used to relate the amount of gas that has encountered shocks within the last ~ 10(6) years to the large scale kinematics in the inner ~ 500 pc of the Galaxy. Based on observations obtained at the Swedish-ESO Submillimeter Telescope (SEST, Project C

  1. The nuclear region of the spiral galaxy M81.

    PubMed Central

    Bartel, N; Bietenholz, M F; Rupen, M P

    1995-01-01

    Very-long-baseline radio interferometry images of the nuclear region of the nearby spiral galaxy M81 reveal the most compact galactic core outside the Galaxy of which the size has been determined: 700 x 300 astronomical units (AU). The observations exclude a starburst or supernova interpretation for the core. Instead they favor an active galactic nucleus. There is evidence for a northeastern jet bent by approximately 35 degrees over a length scale from 700 to 4000 AU. The jet is, on average, directed toward an extended emission region, probably a radio lobe, about 1 kiloparsec (kpc) away from the core. A corresponding emission region was found in the southwest at a distance of only 30 pc from the core. The observed jet is extremely stable and likely to be associated with a steady-state channel. There is no detectable motion along the jet beyond the nominal value of -60 +/- 60 km.s-1. The level of activities in the core region of M81 is intermediate between that of SgrA* and that of powerful radio galaxies and quasars. Images Fig. 1 PMID:11607601

  2. Abundances of argon, sulfur, and neon in six galactic H II regions from infrared forbidden lines

    NASA Technical Reports Server (NTRS)

    Herter, T.; Helfer, H. L.; Forrest, W. J.; Mccarthy, J.; Houck, J. R.; Willner, S. P.; Puetter, R. C.; Rudy, R. J.; Soifer, B. T.; Pipher, J. L.

    1981-01-01

    Airborne measurements of the Ar II (6.99 micron) and S III (18.71 micron) forbidden lines for six compact H II regions are presented, as well as ground-based 2-4 micron and 8-13 micron spectroscopy if not already published. From these data and radio data, lower limits to the elemental abundances of Ar, Ne, and S are deduced. G29.9-0.0, at 5 kpc from the galactic center, is overabundant in all these elements. The other five regions (at distances 6-13 kpc from the center) mainly appear to be consistent with standard abundances, with the exception of G75.84 + 0.4 at 10 kpc from the galactic center, which is overabundant in S. However, preliminary results on G12.8-0.2 at 6 kpc from the galactic center suggest a possible underabundance. A large statistical sample of H II regions is required in order to determine if there is a radial gradient in the heavy element abundances of the Galaxy.

  3. Large-Scale Structures in the Zone of Avoidance: The Galactic Anticenter Region

    NASA Technical Reports Server (NTRS)

    Lu, Nanyao Y.; Freudling, Wolfram

    1995-01-01

    We have selected a sample of 876 galaxy candidates from the IRAS Point Source Catalog in the region of 2(exp h) < alpha < 10(exp h) and 0 deg < delta < 36 deg, which crosses the Galactic anticenter part of the Zone of Avoidance (ZOA) and includes most of the highly obscured Orion-Taurus complex region. We have identified galaxies among the candidate sources by attempting to detect the 21 cm H I line of those sources which were not known to be galaxies at the beginning of the survey. In this manner, we constructed a galaxy sample which is largely free from Galactic reddening. Of the 272 observed candidates, 89 were detected in the H I line up to a heliocentric velocity of v(sub h) approximately 16,000 km/s. The resulting galaxy sample of 717 galaxies is fairly complete (within about 10%) and uniform (within about 4%) in the part of the survey area 10 deg away from the Galactic plane and for velocities up to at least 9000 km/s. This provides, for the first time, a largely unbiased view on the large-scale structures in much of the survey area. Our main results are the following: (1) Several large voids are identified. In particular, a void between alpha approximately equals 3(sup h) and 4(sup h), up to v(sub h) approximately 6000 km/s, separates the Pisces-Perseus supercluster at alpha < 3(sup h) from structures at alpha > 4(sup h); and a "nearby void" occupies most of our survey area and reaches out to a redshift of nearly 3000 km/s. (2) We found no nearby galaxy concentration that could significantly contribute to the "Local Velocity Anomoly" (LVA), but a general excess of galaxies around v(sub h) approximately 5000 km/s in the survey area. (3) The contrast between the "Great Wall" at v(sub h) approximately 8500 km/s and the void in front of it appears to gradually diffuse out after it enters the Zone of Avoidance from the northern Galactic hemisphere. (4) Our data combined with other galaxy surveys in or near the Galactic anticenter part of the ZOA suggest that the

  4. A CS J = 2 1 survey of the galactic center region

    NASA Technical Reports Server (NTRS)

    Stark, A. A.; Bally, J.; Dragovan, M.; Wilson, R. W.

    1986-01-01

    A CS map of the galactic center region is presented consisting of 15,000 spectra covering -1 deg. less than 3. deg. 6 min., -0 deg.4 min. less than b less than 0 deg. 4 min., each having an rms noise of 0.15 K in 1 MHz filters. CS is a high-excitation molecule, meaning that it is excited into emission only when the ambient density is less than n much greater than or approx. 2 x 10 to the 4th power/cu cm CS emission in the inner 2 deg. of the galaxy is nearly as pervasive as CO emission, in stark contrast to the outer galaxy where CS emission is confined to cloud cores. Galactic center clouds are on average much more dense than outer Galaxy clouds. This can be understood as a necessary consequence of the strong tidal stresses in the inner galaxy.

  5. Kinetic temperatures toward X1/X2 orbit interceptions regions and giant molecular loops in the Galactic center region

    NASA Astrophysics Data System (ADS)

    Riquelme, D.; Amo-Baladrón, M. A.; Martín-Pintado, J.; Mauersberger, R.; Martín, S.; Bronfman, L.

    2013-01-01

    Context. It is well known that the kinetic temperatures, Tkin, of the molecular clouds in the Galactic center region are higher than in typical disk clouds. However, the Tkin of the molecular complexes found at higher latitudes towards the giant molecular loops in the central region of the Galaxy is so far unknown. The gas of these high-latitude molecular clouds (hereafter referred to as "halo clouds") is located in a region where the gas in the disk may interact with the gas in the halo in the Galactic center region. Aims: To derive Tkin in the molecular clouds at high latitude and understand the physical process responsible for the heating of the molecular gas both in the central molecular zone (the concentration of molecular gas in the inner ~500 pc) and in the giant molecular loops. Methods: We measured the metastable inversion transitions of NH3 from (J,K) = (1,1) to (6,6) toward six positions selected throughout the Galactic central disk and halo. We used rotational diagrams and large velocity gradient (LVG) modeling to estimate the kinetic temperatures toward all the sources. We also observed other molecules like SiO, HNCO, CS, C34S, C18O, and 13CO, to derive the densities and to trace different physical processes (shocks, photodissociation, dense gas) expected to dominate the heating of the molecular gas. Results: We derive for the first time Tkin of the high-latitude clouds interacting with the disk in the Galactic center region. We find high rotational temperatures in all the observed positions. We derive two kinetic temperature components (~150 K and ~40 K) for the positions in the central molecular zone, and only the warm kinetic temperature component for the clouds toward the giant molecular loops. The fractional abundances derived from the different molecules suggest that shocks provide the main heating mechanism throughout the Galactic center, also at high latitudes. Appendices A and B are available in electronic form at http://www.aanda.org

  6. Hard X-ray observations of the region from the galactic center to Centaurus

    NASA Technical Reports Server (NTRS)

    Guo, D. D.; Webber, W. R.; Damle, S. V.

    1974-01-01

    A balloon flight from Parana, Argentina, was conducted to observe emissions from discrete or extended sources in the southern sky. The sources observed include GX 304-1, Nor X-2, GX 340+0, GX 354-5, a possibly composite source near the galactic center, and the nova-like source (2U1543-47) in the Lupus-Norma region which has been reported previously only in satellite observations. Data concerning the possibility of line emission near 0.5 MeV from different regions of the southern sky are also presented.

  7. A discussion of the H-alpha filamentary nebulae and galactic structure in the Cygnus region

    NASA Technical Reports Server (NTRS)

    Matthews, T. A.; Simonson, S. C., III

    1971-01-01

    From observation of the galactic structure in Cygnus, the system of filamentary nebulae was found to lie at a distance of roughly 1.5 kpc, in the same region as about half the thermal radio sources in Cygnus X, the supernova remnant near gamma Cygni, and the association Cygnus OB2, in the direction of which the X-ray source Cygnus XR-3 is observed. The source of excitation was probably the pulse of radiation from a supernova explosion, as proposed in the case of Gum nebula. However continuing excitation by early stars in the region of Cygnus X cannot be excluded.

  8. Observations of Galactic star-forming regions with the Cosmic Background Imager at 31 GHz

    NASA Astrophysics Data System (ADS)

    Demetroullas, C.; Dickinson, C.; Stamadianos, D.; Harper, S. E.; Cleary, K.; Jones, Michael E.; Pearson, T. J.; Readhead, A. C. S.; Taylor, Angela C.

    2015-10-01

    Studies of the diffuse Galactic radio emission are interesting both for better understanding the physical conditions in our Galaxy and for minimizing the contamination in cosmological measurements. Motivated by this, we present Cosmic Background Imager 31 GHz observations of the Galactic regions NGC 6357, NGC 6334, W51 and W40 at ˜4.5 arcmin resolution and conduct an investigation of the spectral emission process in the regions at 4.5 arcmin and 1° resolution. We find that most of the emission in the regions is due to optically thin free-free. For two sub-regions of NGC 6334 and for a sub-region of W51 though, at 4.5 arcmin resolution and at 31 GHz we detect less emission than expected from extrapolation of radio data at lower frequencies assuming a spectral index of -0.12 for optically thin free-free emission, at 3.3σ, 3.7σ and 6.5σ, respectively. We also detect excess emission in a sub-region of NCG 6334 at 6.4σ, after ruling out any possible contribution from ultra-compact H II regions. At 1° resolution, we detect a spinning dust component in the spectral energy distribution of W40 that accounts for 18 ± 7 per cent of the total flux density in the region at the peak frequency of 37 GHz. Comparison with 100 μm data indicates an average dust emissivity for the sub-regions of 0.5 ± 4.4 μK(MJy sr-1)-1. Finally, we translate the excess emission in the regions to an anomalous microwave emission (AME) emissivity relative to the optical depth at 250 μm. We find that this form of emissivity is independent of the AME significance and has a value somewhere in the order of 104 Jy.

  9. RE-ANALYSIS OF THE RADIO LUMINOSITY FUNCTION OF GALACTIC H II REGIONS

    SciTech Connect

    Paladini, R.; Noriega-Crespo, A.; Carey, S. J.; DeZotti, G.

    2009-09-10

    We have re-analyzed continuum and recombination lines radio data available in the literature in order to derive the luminosity function (LF) of Galactic H II regions. The study is performed by considering the first and fourth Galactic quadrants independently. We estimate the completeness level of the sample in the fourth quadrant at 5 Jy, and the one in the first quadrant at 2 Jy. We show that the two samples (fourth or first quadrant) include, as well as giant and supergiant H II regions, a significant number of subgiant sources. The LF is obtained, in each Galactic quadrant, with a generalized Schmidt's estimator using an effective volume derived from the observed spatial distribution of the considered H II regions. The re-analysis also takes advantage of recently published ancillary absorption data allowing to solve the distance ambiguity for several objects. A single power-law fit to the LFs retrieves a slope equal to -2.23 {+-} 0.07 (fourth quadrant) and to -1.85 {+-} 0.11 (first quadrant). We also find marginal evidence of a luminosity break at L{sub knee} = 10{sup 23.45} erg s{sup -1} Hz{sup -1} for the LF in the fourth quadrant. We convert radio luminosities into equivalent H{alpha} and Lyman continuum luminosities to facilitate comparisons with extragalactic studies. We obtain an average total H II regions Lyman continuum luminosity of 0.89 {+-} 0.23 x 10{sup 53} s{sup -1}, corresponding to 30% of the total ionizing luminosity of the Galaxy.

  10. THE STELLAR CONTENT OF OBSCURED GALACTIC GIANT H II REGIONS. VII. W3

    SciTech Connect

    Navarete, F.; Figueredo, E.; Damineli, A.; Moises, A. P.; Blum, R. D.; Conti, P. S.

    2011-09-15

    Spectrophotometric distances in the K band have been reported by different authors for a number of obscured Galactic H II regions. Almost 50% of them show large discrepancies compared to the classical method using radial velocities measured in the radio spectral region. In order to provide a crucial test of both methods, we selected a target that does not present particular difficulty for any method and which has been measured by as many techniques as possible. The W3 star-forming complex, located in the Perseus arm, offers a splendid opportunity for such a task. We used the Near-Infrared Integral Field Spectrograph on the Frederick C. Gillett Gemini North telescope to classify candidate 'naked photosphere' OB stars based on Two Micron All Sky Survey photometry. Two of the targets are revealed to be mid-O-type main-sequence stars leading to a distance of d = 2.20 kpc. This is in excellent agreement with the spectrophotometric distance derived in the optical band (d = 2.18 pc) and with a measurement of the W3 trigonometric parallax (d = 1.95 kpc). Such results confirm that the spectrophotometric distances in the K band are reliable. The radio-derived kinematic distance, on the contrary, gives a distance twice as large (d = 4.2 kpc). This indicates that this region of the Perseus arm does not follow the Galactic rotation curve, and this may also be the case for other H II regions for which discrepancies have been found.

  11. Disk-Halo interaction: The molecular clouds in the Galactic center region

    NASA Astrophysics Data System (ADS)

    Riquelme, D.; Martín-Pintado, J.; Mauersberger, R.; Amo-Baladrón, M. A.; Martín, S.; Bronfman, L.

    2012-07-01

    From a large-scale study of the Galactic center (GC) region in SiO(2 - 1), HCO+(1 - 0), and H13CO+(1 - 0), we identify shock regions as traced by the enhancement of SiO emission. We selected 9 positions called by us as "interaction regions", because they mark the places where gas in the GC could be interacting with gas coming from higher latitude ("disk-halo interaction") or from larger galactocentric radius. These positions were studied using the 12C/13C isotopic ratio to trace gas accretion/ejection. We found a systematically higher 12C/13C isotopic ratio (> 40) toward the interaction regions than for the GC "standard" molecular clouds (20 - 25). These high isotopic ratios are consistent with the accretion of the gas from higher galactic latitudes or from larger galactocentric distances. There are two kinetic temperature regimes (one warm at ~ 200 K and one cold at ~ 40 K) for all the positions, except for the positions associated to the giant molecular loops where only the warm component is present. Relative molecular abundances suggest that the heating mechanism in the GC is related to shocks. We mapped one molecular cloud placed at the foot points of the giant molecular loops in 3-mm molecular lines to reveal the morphology, chemical composition and the kinematics of the shocked gas.

  12. A starburst region at the tip of the Galactic bar around l=347-350

    NASA Astrophysics Data System (ADS)

    Marco, Amparo; Negueruela, Ignacio; González-Fernández, Carlos; Maíz-Apellániz, Jesús; Dorda, Ricardo; Clark, J. Simon

    2015-08-01

    In the past few years, several clusters of red supergiants have been discovered in a small region of the Milky Way, close to the base of the Scutum-Crux Arm and the tip of the Long Bar, between l=24º and l=29º. According to the number of observed red supergiants and using population synthesis models, they must contain very large stellar populations to harbour so many RSGs, some of them being candidates to the most massive young clusters in the Galaxy. These massive open clusters are part of a huge structure most likely containing hundreds of red supergiants. These results suggest that the Scutum complex represents a giant star formation region triggered by dynamical excitation by the Galactic bar, whose tip is believed to intersect the Scutum-Crux Arm close to this region. If this scenario is correct, a similar structure would be expected close to the opposite end of the Galactic long bar. We must find in an area between l=347º-350º (these sight lines include the expected location of the far tip of the Galactic bar in the model of González-Fernández et al. (2012)) likely candidates to very massive open clusters.We are carrying out a comprehensive optical and infrared photometric and spectroscopic study of this region containing the open clusters VdBH 222, Teutsch 85 and their surroundings. We have analyzed the population of VdBH 222 and we have found a large population of luminous supergiants and OB stars. The cluster lies behind ~7.5 mag of extinction and has a probable distance of ~ 10 kpc and an age of ~12 Ma. VdBH 222 is a young massive cluster with a likely mass > 20000 Msolar. Now, we are analyzing the population of the open cluster Teutsch 85 and surroundings, finding a numerous population of supergiants.In this work, we will discuss the possible role of the Galactic bar in triggering the formation of starburst clusters.

  13. Spectrum and variation of gamma-ray emission from the galactic center region

    NASA Technical Reports Server (NTRS)

    Riegler, G. R.; Ling, J. C.; Mahoney, W. A.; Wheaton, W. A.; Jacobson, A. S.

    1982-01-01

    Continuum emission at 60-300 keV from the galactic center region was observed to decrease in intensity by 45 percent and to show a spectrum steepening between fall 1979 and spring 1980. At the same time 511 keV positron annihilation radiation decreased by a comparable fraction. No variations over shorter time scales were detected. The observations are consistent with a model where positrons and hard X-rays are produced in an electromagnetic cascade near a massive black hole.

  14. Nearby sources in the transition region between Galactic and Extragalactic cosmic rays

    NASA Astrophysics Data System (ADS)

    Sveshnikova, L. G.; Korosteleva, E. E.; Kuzmichev, L. A.; Ptuskin, V. S.; Prosin, V. A.; Strelnikova, O. N.

    2013-02-01

    In this paper, a probable interpretation of a remarkable fine structure of all particle spectra between the knee and the ankle, as well as a high content of heavy nuclei around 1017 eV measured recently in Tunka-133 and KASCADE Grande experiments, is presented: the special class of sources, SN_Ia, provides cosmic rays (CR) around the knee. Subtracting the contribution of them from all particle spectrum we obtained the residual flux of the CR corresponding to the transition region between Galactic and Extragalactic CR in the range 1017 ÷ 5 1018 eV. The obtained spectrum also has a pronounced knee at energy (2÷3)1017 eV and slopes γ1 ~ 1.8+0.3 before it and γ2 ~3.4 above it. We analyzed the possible contribution from known Galactic sources and shown that formally the best candidate to contribute significantly to the transition region is Cas A. This source posses a number of unusual properties and considered as Type IIb SNR. However we show that the hypothesis of extragalactic CR origin providing the region above 1017 eV seems to be more realistic.

  15. NUCLEAR RADIO JET FROM A LOW-LUMINOSITY ACTIVE GALACTIC NUCLEUS IN NGC 4258

    SciTech Connect

    Doi, Akihiro; Kohno, Kotaro; Nakanishi, Kouichiro; Kameno, Seiji; Inoue, Makoto; Hada, Kazuhiro; Sorai, Kazuo

    2013-03-01

    The nearby low-luminosity active galactic nucleus (LLAGN) NGC 4258 has a weak radio continuum component at the galactic center. We investigate its radio spectral properties on the basis of our new observations using the Nobeyama Millimeter Array at 100 GHz and archival data from the Very Large Array at 1.7-43 GHz and the James Clerk Maxwell telescope at 347 GHz. The NGC 4258 nuclear component exhibits (1) an intra-month variable and complicated spectral feature at 5-22 GHz and (2) a slightly inverted spectrum at 5-100 GHz ({alpha} {approx} 0.3; F {sub {nu}}{proportional_to}{nu}{sup {alpha}}) in time-averaged flux densities, which are also apparent in the closest LLAGN M81. These similarities between NGC 4258 and M81 in radio spectral natures in addition to previously known core shift in their AU-scale jet structures produce evidence that the same mechanism drives their nuclei. We interpret the observed spectral property as the superposition of emission spectra originating at different locations with frequency-dependent opacity along the nuclear jet. Quantitative differences between NGC 4258 and M81 in terms of jet/counter jet ratio, radio loudness, and degree of core shift can be consistently understood by fairly relativistic speeds ({Gamma} {approx}> 3) of jets and their quite different inclinations. The picture established from the two closest LLAGNs is useful for understanding the physical origin of unresolved and flat/inverted spectrum radio cores that are prevalently found in LLAGNs, including Sgr A*, with starved supermassive black holes in the present-day universe.

  16. Nuclear Radio Jet from a Low-luminosity Active Galactic Nucleus in NGC 4258

    NASA Astrophysics Data System (ADS)

    Doi, Akihiro; Kohno, Kotaro; Nakanishi, Kouichiro; Kameno, Seiji; Inoue, Makoto; Hada, Kazuhiro; Sorai, Kazuo

    2013-03-01

    The nearby low-luminosity active galactic nucleus (LLAGN) NGC 4258 has a weak radio continuum component at the galactic center. We investigate its radio spectral properties on the basis of our new observations using the Nobeyama Millimeter Array at 100 GHz and archival data from the Very Large Array at 1.7-43 GHz and the James Clerk Maxwell telescope at 347 GHz. The NGC 4258 nuclear component exhibits (1) an intra-month variable and complicated spectral feature at 5-22 GHz and (2) a slightly inverted spectrum at 5-100 GHz (α ~ 0.3; F νvpropνα) in time-averaged flux densities, which are also apparent in the closest LLAGN M81. These similarities between NGC 4258 and M81 in radio spectral natures in addition to previously known core shift in their AU-scale jet structures produce evidence that the same mechanism drives their nuclei. We interpret the observed spectral property as the superposition of emission spectra originating at different locations with frequency-dependent opacity along the nuclear jet. Quantitative differences between NGC 4258 and M81 in terms of jet/counter jet ratio, radio loudness, and degree of core shift can be consistently understood by fairly relativistic speeds (Γ >~ 3) of jets and their quite different inclinations. The picture established from the two closest LLAGNs is useful for understanding the physical origin of unresolved and flat/inverted spectrum radio cores that are prevalently found in LLAGNs, including Sgr A*, with starved supermassive black holes in the present-day universe.

  17. Magnetically elevated accretion disks in active galactic nuclei: broad emission line regions and associated star formation

    NASA Astrophysics Data System (ADS)

    Begelman, Mitchell C.; Silk, Joseph

    2016-10-01

    We propose that the accretion disks fueling active galactic nuclei are supported vertically against gravity by a strong toroidal (φ -direction) magnetic field that develops naturally as the result of an accretion disk dynamo. The magnetic pressure elevates most of the gas carrying the accretion flow at R to large heights z ˜ 0.1 R and low densities, while leaving a thin dense layer containing most of the mass - but contributing very little accretion - around the equator. We show that such a disk model leads naturally to the formation of a broad emission line region through thermal instability. Extrapolating to larger radii, we demonstrate that local gravitational instability and associated star formation are strongly suppressed compared to standard disk models for AGN, although star formation in the equatorial zone is predicted for sufficiently high mass supply rates. This new class of accretion disk models thus appears capable of resolving two longstanding puzzles in the theory of AGN fueling: the formation of broad emission line regions and the suppression of fragmentation thought to inhibit accretion at the required rates. We show that the disk of stars that formed in the Galactic Center a few million years ago could have resulted from an episode of magnetically elevated accretion at ˜0.1 of the Eddington limit.

  18. The galactic center region imaged by VERITAS from 2010-2012

    NASA Astrophysics Data System (ADS)

    Beilicke, M.; VERITAS Collaboration

    2012-12-01

    The galactic center (GC) has long been a region of interest for high-energy and very-high-energy observations. Many potential sources of GeV/TeV γ-ray emission are located in the GC region, e.g. the accretion of matter onto the central black hole (BH), cosmic rays from a nearby shell-type super nova remnant, or the annihilation of dark matter. The GC has been detected at MeV/GeV energies by EGRET and recently by Fermi/LAT. At TeV energies, the GC was detected at the level of 4 standard deviations with the Whipple 10m telescope and with one order of magnitude better sensitivity by H.E.S.S. and MAGIC. We present the results from 3 years of VERITAS GC observations conducted at large zenith angles (LZA). The results are compared to astrophysical models.

  19. Agriculture Impacts of Regional Nuclear Conflict

    NASA Astrophysics Data System (ADS)

    Xia, Lili; Robock, Alan; Mills, Michael; Toon, Owen Brian

    2013-04-01

    One of the major consequences of nuclear war would be climate change due to massive smoke injection into the atmosphere. Smoke from burning cities can be lofted into the stratosphere where it will have an e-folding lifetime more than 5 years. The climate changes include significant cooling, reduction of solar radiation, and reduction of precipitation. Each of these changes can affect agricultural productivity. To investigate the response from a regional nuclear war between India and Pakistan, we used the Decision Support System for Agrotechnology Transfer agricultural simulation model. We first evaluated the model by forcing it with daily weather data and management practices in China and the USA for rice, maize, wheat, and soybeans. Then we perturbed observed weather data using monthly climate anomalies for a 10-year period due to a simulated 5 Tg soot injection that could result from a regional nuclear war between India and Pakistan, using a total of 100 15 kt atomic bombs, much less than 1% of the current global nuclear arsenal. We computed anomalies using the NASA Goddard Institute for Space Studies ModelE and NCAR's Whole Atmosphere Community Climate Model (WACCM). We perturbed each year of the observations with anomalies from each year of the 10-year nuclear war simulations. We found that different regions respond differently to a regional nuclear war; southern regions show slight increases of crop yields while in northern regions crop yields drop significantly. Sensitivity tests show that temperature changes due to nuclear war are more important than precipitation and solar radiation changes in affecting crop yields in the regions we studied. In total, crop production in China and the USA would decrease 15-50% averaged over the 10 years using both models' output. Simulations forced by ModelE output show smaller impacts than simulations forced by WACCM output at the end of the 10 year period because of the different temperature responses in the two models.

  20. Optical and near-infrared polarimetric study of the RCW121 Galactic H II region

    NASA Astrophysics Data System (ADS)

    Serón Navarrete, J. C.; Roman-Lopes, A.; Santos, Fabio. P.; Franco, G. A. P.; Reis, W.

    2016-10-01

    We present a polarimetric study of the RCW121 star-forming region to derive the orientation of the sky-projected magnetic field component traced by the polarization vectors, the morphology of which tends to follow the cloud's structure. Individual polarization-angle values are consistent across the different bands, having a broad distribution towards the RCW121 H II region. We estimate the corresponding magnetic field orientation in the H II region to have a mean value of -12° ± 7°. RCW121 shows an elongated shape in the same direction as the magnetic field orientation, which may be evidence that magnetic pressure opposes the H II region expansion. Serkowski's relation was used to determine individual values of the total-to-selective extinction ratio (RV) distribution and a weighted mean value of RV = 3.17 ± 0.05. We derive a foreground component of the polarization degree that is consistent with the literature value for this Galactic region.

  1. Observations of medium-energy gamma-ray emission from the galactic center region

    NASA Technical Reports Server (NTRS)

    Kniffen, D. A.; Bertsch, D. L.; Morris, D. J.; Palmeira, R. A. R.; Rao, K. R.

    1978-01-01

    Measurements of the gamma-ray emission in the medium-energy range between 15 and 100 MeV, obtained during two balloon flights from Brazil, are presented. The importance of this energy region in determining whether neutral-pion decay or electron bremsstrahlung is the most likely dominant source mechanism is discussed, along with the implications of such observations. Specifically, the data from this experiment suggest that emission from the galactic plane is similar to the theoretical spectrum calculated by Fichtel et al. (1976), including both source mechanisms but with the bremsstrahlung component enhanced by a factor of about 2. A spectral distribution of gamma-rays produced in the residual atmosphere above the instrument is also presented and compared with other data. A rather smooth spectral variation from high to low energies is found for the atmospheric spectrum.

  2. Observations of medium energy gamma ray emission from the galactic center region

    NASA Technical Reports Server (NTRS)

    Kniffen, D. A.; Bertsch, D. L.; Morris, D. J.; Palmeira, R. A. R.; Rao, K. R.

    1978-01-01

    Measurements of the gamma-ray emission in the medium energy range between 15 and 100 MeV, obtained during two ballon flights from Brazil are presented. The importance of this energy region in determining whether pi deg - decay of electron bremsstrahlung is the most likely dominant source mechanism is discussed along with the implications of such observations. Specifically, the data from this experiment suggest that emission from the galactic plane is similar to theoretical spectrum calculations including both sources mechanisms, but with the bremsstrahlung component enhanced by a factor of about 2. A spectral distribution of gamma-rays produced in the residual atmosphere above the instrument is also presented and compared with other data. A rather smooth spectral variation from high to low energies is found for the atmospheric spectrum.

  3. Consequences of hot gas in the broad line region of active galactic nuclei

    NASA Technical Reports Server (NTRS)

    Kallman, T.; Mushotzky, R.

    1985-01-01

    Models for hot gas in the broad line region of active galactic nuclei are discussed. The results of the two phase equilibrium models for confinement of broad line clouds by Compton heated gas are used to show that high luminosity quasars are expected to show Fe XXVI L alpha line absorption which will be observed with spectrometers such as those planned for the future X-ray spectroscopy experiments. Two phase equilibrium models also predict that the gas in the broad line clouds and the confining medium may be Compton thick. It is shown that the combined effects of Comptonization and photoabsorption can suppress both the broad emission lines and X-rays in the Einstein and HEAO-1 energy bands. The observed properties of such Compton thick active galaxies are expected to be similar to those of Seyfert 2 nuclei. The implications for polarization and variability are also discussed.

  4. Concentric Radio Shells around Pistol-Quintuplet Stars in the Galactic Center Arc Region

    NASA Astrophysics Data System (ADS)

    Sofue, Y.

    1999-12-01

    By filtering out the straight filaments of the Galactic Cente Arc in VLA radio images of Yusef-Zadeh and Morris, we show that numerous concentric radio shells and arcs of radii 5 to 10 pc are coherently surrounding the Pistol and Sickle region. Each shell has a thermal energy of the order of 1049 ergs. Several CO-line shells are found toward the radio shells with kinetic energy of the order of 1049-50 ergs. We propose a new idea that the concentric shell structure has the common origin: they are expanding fronts from intermittent outflows and/or ionization due to successive star-forming activities near to the Pistol and Quintuplet stars.

  5. 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.

  6. How Space Radiation Risk from Galactic Cosmic Rays at the International Space Station Relates to Nuclear Cross Sections

    NASA Technical Reports Server (NTRS)

    Lin, Zi-Wei; Adams, J. H., Jr.

    2005-01-01

    Space radiation risk to astronauts is a major obstacle for long term human space explorations. Space radiation transport codes have thus been developed to evaluate radiation effects at the International Space Station (ISS) and in missions to the Moon or Mars. We study how nuclear fragmentation processes in such radiation transport affect predictions on the radiation risk from galactic cosmic rays. Taking into account effects of the geomagnetic field on the cosmic ray spectra, we investigate the effects of fragmentation cross sections at different energies on the radiation risk (represented by dose-equivalent) from galactic cosmic rays behind typical spacecraft materials. These results tell us how the radiation risk at the ISS is related to nuclear cross sections at different energies, and consequently how to most efficiently reduce the physical uncertainty in our predictions on the radiation risk at the ISS.

  7. Effects of Nuclear Cross Sections at Different Energies on Space Radiation Exposure from Galactic Cosmic Rays

    NASA Technical Reports Server (NTRS)

    Li, Zi-Wei; Adams, James H., Jr.

    2007-01-01

    Space radiation from galactic cosmic rays (GCR) is a major hazard to space crews, especially in long duration human space explorations. For this reason, they will be protected by radiation shielding that fragments the GCR heavy ions. Here we investigate how sensitive the crew's radiation exposure is to nuclear fragmentation cross sections at different energies. We find that in deep space cross sections between about 0.2 and 1.2 GeV/u have the strongest effect on dose equivalent behind shielding in solar minimum GCR environments, and cross sections between about 0.6 and 1.7 GeV/u are the most important at solar maximum'. On the other hand, at the location of the International Space Station, cross sections at_higher -energies, between about 0.6 and 1.7 GeV /u at solar minimum and between about 1.7 and 3.4 GeV/u'at,solar maximum, are the most important This is. due-to the average geomagnetic cutoff for the ISS orbit. We also show the effect of uncertainties in the fragmentation cross sections on the elemental energy spectra behind shielding. These results help to focus the studies of fragmentation cross sections on the proper energy range in order to improve our predictions of crew exposures.

  8. ISOTOPIC RATIOS OF {sup 18}O/{sup 17}O IN THE GALACTIC CENTRAL REGION

    SciTech Connect

    Zhang, J. S.; Sun, L. L.; Riquelme, D.; Henkel, C.; Lu, D. R.; Zhang, Y.; Wang, J. Z.; Li, J.; Wang, M.

    2015-08-15

    The {sup 18}O/{sup 17}O isotopic ratio of oxygen is a crucial measure of the secular enrichment of the interstellar medium by ejecta from high-mass versus intermediate-mass stars. So far, however, there is a lack of data, particularly from the Galactic center (GC) region. Therefore, we have mapped typical molecular clouds in this region in the J = 1–0 lines of C{sup 18}O and C{sup 17}O with the Delingha 13.7 m telescope (DLH). Complementary pointed observations toward selected positions throughout the GC region were obtained with the IRAM 30 m and Mopra 22 m telescopes. C{sup 18}O/C{sup 17}O abundance ratios reflecting the {sup 18}O/{sup 17}O isotope ratios were obtained from integrated intensity ratios of C{sup 18}O and C{sup 17}O. For the first time, C{sup 18}O/C{sup 17}O abundance ratios are determined for Sgr C (V ∼ −58 km s{sup −1}), Sgr D (V ∼ 80 km s{sup −1}), and the 1.°3 complex (V ∼ 80 km s{sup −1}). Through our mapping observations, abundance ratios are also obtained for Sgr A (∼0 and ∼50 km s{sup −1} component) and Sgr B2 (∼60 km s{sup −1}), which are consistent with the results from previous single-point observations. Our frequency-corrected abundance ratios of the GC clouds range from 2.58 ± 0.07 (Sgr D, V ∼ 80 km s{sup −1}, DLH) to 3.54 ± 0.12 (Sgr A, ∼50 km s{sup −1}). In addition, strong narrow components (line width less than 5 km s{sup −1}) from the foreground clouds are detected toward Sgr D (−18 km s{sup −1}), the 1.°3 complex (−18 km s{sup −1}), and M+5.3−0.3 (22 km s{sup −1}), with a larger abundance ratio around 4.0. Our results show a clear trend of lower C{sup 18}O/C{sup 17}O abundance ratios toward the GC region relative to molecular clouds in the Galactic disk. Furthermore, even inside the GC region, ratios appear not to be uniform. The low GC values are consistent with an inside-out formation scenario for our Galaxy.

  9. Bridging the gap: A Spitzer Census of Intermediate-Mass Star Forming Regions from Galactic Surveys.

    NASA Astrophysics Data System (ADS)

    Kerton, Charles; Kobulnicky, Chip

    2008-03-01

    High-mass star formation (M>10 Msun) appears to proceed through different channels than low-mass star formation (M<2 Msun). The differences between these two regimes are thought to include not only the timescales and masses involved but also the initial conditions and operative physics within the parent molecular clouds. We propose an archival analysis of ~50 *intermediate-mass* star formation (SF) regions that straddle the boundary between these two regimes---regions forming stars up to 4-8 Msun. These, relatively unknown and unstudied IR sources are selected by their IRAS colors and lie within the Spitzer GLIMPSE+MIPSGAL legacy survey fields. Compared to their more famous high-mass SF cousins (e.g., the Westerhout 'W' HII objects), these regions are radio-quiet, relatively nearby, and structurally less complex. We will use complementary public-domain 13CO, 21-cm, and radio continuum Galactic surveys to 1) confirm the intermediate-mass SF nature of these objects, 2) compile a catalog and an atlas of mid-IR morphologies, 3) estimate distances, 4) calculate total luminosities and gas masses of affiliated molecular and atomic material, and 5) identify associated young stellar objects using IRAC+[24] colors. This work will provide a benchmark useful for contrasting the star formation process in both lower-mass and higher-mass SF environments.

  10. 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.

  11. Chandra Deep X-ray Observation of a Typical Galactic Plane Region and Near-Infrared Identification

    NASA Technical Reports Server (NTRS)

    Ebisawa, K.; Tsujimoto, M.; Paizis, A.; Hamaguichi, K.; Bamba, A.; Cutri, R.; Kaneda, H.; Maeda, Y.; Sato, G.; Senda, A.

    2004-01-01

    Using the Chandra Advanced CCD Imaging Spectrometer Imaging array (ACIS-I), we have carried out a deep hard X-ray observation of the Galactic plane region at (l,b) approx. (28.5 deg,0.0 deg), where no discrete X-ray source has been reported previously. We have detected 274 new point X-ray sources (4 sigma confidence) as well as strong Galactic diffuse emission within two partidly overlapping ACIS-I fields (approx. 250 sq arcmin in total). The point source sensitivity was approx. 3 x 10(exp -15)ergs/s/sq cm in the hard X-ray band (2-10 keV and approx. 2 x 10(exp -16) ergs/s/sq cm in the soft band (0.5-2 keV). Sum of all the detected point source fluxes account for only approx. 10 % of the total X-ray fluxes in the field of view. In order to explain the total X-ray fluxes by a superposition of fainter point sources, an extremely rapid increase of the source population is required below our sensitivity limit, which is hardly reconciled with any source distribution in the Galactic plane. Therefore, we conclude that X-ray emission from the Galactic plane has truly diffuse origin. Only 26 point sources were detected both in the soft and hard bands, indicating that there are two distinct classes of the X-ray sources distinguished by the spectral hardness ratio. Surface number density of the hard sources is only slightly higher than observed at the high Galactic latitude regions, strongly suggesting that majority of the hard X-ray sources are active galaxies seen through the Galactic plane. Following the Chandra observation, we have performed a near-infrared (NIR) survey with SOFI at ESO/NTT to identify these new X-ray sources. Since the Galactic plane is opaque in NIR, we did not see the background extragalactic sources in NIR. In fact, only 22 % of the hard sources had NIR counterparts which are most likely to be Galactic origin. Composite X-ray energy spectrum of those hard X-ray sources having NIR counterparts exhibits a narrow approx. 6.7 keV iron emission line, which

  12. THE BOLOCAM GALACTIC PLANE SURVEY: {lambda} = 1.1 AND 0.35 mm DUST CONTINUUM EMISSION IN THE GALACTIC CENTER REGION

    SciTech Connect

    Bally, John; Battersby, Cara; Ginsburg, Adam; Glenn, Jason; Harvey, Paul; Stringfellow, Guy S. E-mail: Cara.Battersby@colorado.ed E-mail: pmh@astro.as.utexas.ed

    2010-09-20

    The Bolocam Galactic Plane Survey (BGPS) data for a 6 deg{sup 2} region of the Galactic plane containing the Galactic center are analyzed and compared to infrared and radio continuum data. The BGPS 1.1 mm emission consists of clumps interconnected by a network of fainter filaments surrounding cavities, a few of which are filled with diffuse near-IR emission indicating the presence of warm dust or with radio continuum characteristic of H II regions or supernova remnants. New 350 {mu}m images of the environments of the two brightest regions, Sgr A and B, are presented. Sgr B2 is the brightest millimeter-emitting clump in the Central Molecular Zone (CMZ) and may be forming the closest analog to a super star cluster in the Galaxy. The CMZ contains the highest concentration of millimeter- and submillimeter-emitting dense clumps in the Galaxy. Most 1.1 mm features at positive longitudes are seen in silhouette against the 3.6-24 {mu}m background observed by the Spitzer Space Telescope. However, only a few clumps at negative longitudes are seen in absorption, confirming the hypothesis that positive longitude clumps in the CMZ tend to be on the near side of the Galactic center, consistent with the suspected orientation of the central bar in our Galaxy. Some 1.1 mm cloud surfaces are seen in emission at 8 {mu}m, presumably due to polycyclic aromatic hydrocarbons. A {approx}0.{sup 0}2 ({approx}30 pc) diameter cavity and infrared bubble between l{approx} 0.{sup 0}0 and 0.{sup 0}2 surround the Arches and Quintuplet clusters and Sgr A. The bubble contains several clumpy dust filaments that point toward Sgr A*; its potential role in their formation is explored. Bania's Clump 2, a feature near l = 3{sup 0}-3.{sup 0}5 which exhibits extremely broad molecular emission lines ({Delta}V> 150 km s{sup -1}), contains dozens of 1.1 mm clumps. These clumps are deficient in near- and mid-infrared emission in the Spitzer images when compared to both the inner Galactic plane and the CMZ. Thus

  13. Star Formation Activity in the Galactic H II Region Sh2-297

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

    We present a multiwavelength study of the Galactic H II region Sh2-297, located in the Canis Major OB1 complex. Optical spectroscopic observations are used to constrain the spectral type of ionizing star HD 53623 as B0V. The classical nature of this H II region is affirmed by the low values of electron density and emission measure, which are calculated to be 756 cm-3 and 9.15 × 105 cm-6 pc using the radio continuum observations at 610 and 1280 MHz, and Very Large Array archival data at 1420 MHz. To understand local star formation, we identified the young stellar object (YSO) candidates in a region of area ~7farcm5 × 7farcm5 centered on Sh2-297 using grism slitless spectroscopy (to identify the Hα emission line stars), and near infrared (NIR) observations. NIR YSO candidates are further classified into various evolutionary stages using color-color and color-magnitude (CM) diagrams, giving 50 red sources (H - K > 0.6) and 26 Class II-like sources. The mass and age range of the YSOs are estimated to be ~0.1-2 M ⊙ and 0.5-2 Myr using optical (V/V-I) and NIR (J/J-H) CM diagrams. The mean age of the YSOs is found to be ~1 Myr, which is of the order of dynamical age of 1.07 Myr of the H II region. Using the estimated range of visual extinction (1.1-25 mag) from literature and NIR data for the region, spectral energy distribution models have been implemented for selected YSOs which show masses and ages to be consistent with estimated values. The spatial distribution of YSOs shows an evolutionary sequence, suggesting triggered star formation in the region. The star formation seems to have propagated from the ionizing star toward the cold dark cloud LDN1657A located west of Sh2-297.

  14. The Schmidt Law in Six Galactic Massive Star-forming Regions

    NASA Astrophysics Data System (ADS)

    Willis, S.; Guzman, A.; Marengo, M.; Smith, H. A.; Martínez-Galarza, J. R.; Allen, L.

    2015-08-01

    We present a census of young stars in five massive star-forming regions in the 4th Galactic quadrant, G305, G326-4, G326-6, G333 (RCW 106), and G351, and combine this census with an earlier census of young stars in NGC 6334. Each region was observed at J, H, and Ks with the NOAO Extremely Wide-Field Infrared Imager and combined with deep observations taken with the Infrared Array Camera (IRAC) on board the Spitzer Space Telescope at the wavelengths 3.6 and 4.5 μm. We derived a five band point-source catalog containing >200,000 infrared sources in each region. We have identified a total of 2871 YSO candidates, 363 Class I YSOs, and 2508 Class II YSOs. We mapped the column density of each cloud using observations from Herschel between 160 and 500 μm and near-infrared extinction maps in order to determine the average gas surface density above AV > 2. We study the surface density of the YSOs and the star-formation rate as a function of the column density within each cloud and compare them to the results for nearby star-forming regions. We find a range in power-law indices across the clouds, with the dispersion in the local relations in an individual cloud much lower than the average over the six clouds. We find the average over the six clouds to be {{{Σ }}}{SFR}∼ {{{Σ }}}{gas}2.15+/- 0.41 and power-law exponents ranging from 1.77 to 2.86, similar to the values derived within nearby star-forming regions, including Taurus and Orion. The large dispersion in the power-law relations between individual Milky Way molecular clouds reinforces the idea that there is not a direct universal connection between Σgas and a cloud's observed star-formation rate.

  15. Stellar populations in the Carina region. The Galactic plane at l = 291°

    NASA Astrophysics Data System (ADS)

    Molina-Lera, J. A.; Baume, G.; Gamen, R.; Costa, E.; Carraro, G.

    2016-08-01

    Context. Previous studies of the Carina region have revealed its complexity and richness as well as a significant number of early-type stars. However, in many cases, these studies only concentrated on the central region (Trumpler 14/16) or were not homogeneous. This latter aspect, in particular, is crucial because very different ages and distances for key clusters have been claimed in recent years. Aims: The aim of this work is to study in detail an area of the Galactic plane in Carina, eastward η Carina. We analyze the properties of different stellar populations and focus on a sample of open clusters and their population of young stellar objects and highly reddened early stars. We also studied the stellar mass distribution in these clusters and the possible scenario of their formation. Finally, we outline the Galactic spiral structure in this direction. Methods: We obtained deep and homogeneous photometric data (UBVIKC) for six young open clusters: NGC 3752, Trumpler 18, NGC 3590, Hogg 10, 11, and 12, located in Carina at l ~ 291°, and their adjacent stellar fields, which we complemented with spectroscopic observations of a few selected targets. We also culled additional information from the literature, which includes stellar spectral classifications and near-infrared photometry from 2MASS. We finally developed a numerical code that allowed us to perform a homogeneous and systematic analysis of the data. Our results provide more reliable estimates of distances, color excesses, masses, and ages of the stellar populations in this direction. Results: We estimate the basic parameters of the studied clusters and find that they identify two overdensities of young stellar populations located at about 1.8 kpc and 2.8 kpc, with EB - V ~ 0.1 - 0.6. We find evidence of pre-main-sequence populations inside them, with an apparent coeval stellar formation in the most conspicuous clusters. We also discuss apparent age and distance gradients in the direction NW-SE. We study the

  16. Radiation pressure confinement - II. Application to the broad-line region in active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Baskin, Alexei; Laor, Ari; Stern, Jonathan

    2014-02-01

    Active galactic nuclei (AGN) are characterized by similar broad emission lines properties at all luminosities (1039 - 1047 erg s-1). What produces this similarity over a vast range of 108 in luminosity? Photoionization is inevitably associated with momentum transfer to the photoionized gas. Yet, most of the photoionized gas in the broad-line region (BLR) follows Keplerian orbits, which suggests that the BLR originates from gas with a large enough column for gravity to dominate. The photoionized surface layer of the gas must develop a pressure gradient due to the incident radiation force. We present solutions for the structure of such a hydrostatic photoionized gas layer in the BLR. The gas is stratified, with a low-density highly ionized surface layer, a density rise inwards and a uniform-density cooler inner region, where the gas pressure reaches the incident radiation pressure. This radiation pressure confinement (RPC) of the photoionized layer leads to a universal ionization parameter U ˜ 0.1 in the inner photoionized layer, independent of luminosity and distance. Thus, RPC appears to explain the universality of the BLR properties in AGN. We present predictions for the BLR emission per unit covering factor, as a function of distance from the ionizing source, for a range of ionizing continuum slopes and gas metallicity. The predicted mean strength of most lines (excluding H β), and their different average-emission radii, are consistent with available observations.

  17. ORIENTATION EFFECTS ON THE INNER REGION OF DUSTY TORUS OF ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Kawaguchi, Toshihiro; Mori, Masao

    2010-12-01

    A sublimation process governs the innermost region of the dusty torus of active galactic nuclei. However, the observed inner radius of the torus is systematically smaller than the expected radius by a factor of {approx}1/3. We show that the anisotropy of the emission from accretion disks resolves this conflict naturally and quantitatively. An accretion disk emits lesser radiation in the direction closer to its equatorial plane (i.e., to the torus). We find that the anisotropy makes the torus inner region closer to the central black hole and concave. Moreover, the innermost edge of the torus may connect with the outermost edge of the disk continuously. Considering the anisotropic emission of each clump in the torus, we calculate the near-infrared flux variation in response to a UV flash. For an observer at the polar angle {theta}{sub obs} = 25{sup 0}, the centroid of the time delay is found to be 37% of the delay expected in the case of isotropic illumination, which explains the observed systematic deviation.

  18. THE COMPLEX NORTH TRANSITION REGION OF CENTAURUS A: A GALACTIC WIND

    SciTech Connect

    Neff, Susan G.; Eilek, Jean A.; Owen, Frazer N.

    2015-04-01

    We present deep GALEX images of NGC 5128, the parent galaxy of Centaurus A. We detect a striking “weather ribbon” of far-UV (FUV) and Hα emission which extends more than 35 kpc northeast of the galaxy. This ribbon is associated with a knotty ridge of radio/X-ray emission and is an extension of the previously known string of optical emission-line filaments. Many phenomena in the region are too short-lived to have survived transit out from the inner galaxy; something must be driving them locally. We also detect FUV emission from the galaxy’s central dust lane. Combining this with previous radio and far-IR measurements, we infer an active starburst in the central galaxy which is currently forming stars at ∼2 M{sub ☉} yr{sup −1}, and has been doing so for 50–100 Myr. If the wind from this starburst is enhanced by energy and mass driven out from the active galactic nucleus, the powerful augmented wind can be the driver needed for the northern weather system. We argue that both the diverse weather system, and the enhanced radio emission in the same region, result from the wind’s encounter with cool gas left by one of the recent merger/encounter events in the history of NGC 5128.

  19. Faint emission lines in the Galactic HII regions M16, M20 and NGC 3603*

    NASA Astrophysics Data System (ADS)

    García-Rojas, J.; Esteban, C.; Peimbert, M.; Costado, M. T.; Rodríguez, M.; Peimbert, A.; Ruiz, M. T.

    2006-05-01

    We present deep echelle spectrophotometry of the Galactic HII regions M16, M20 and NGC 3603. The data have been taken with the Very Large Telescope Ultraviolet-Visual Echelle Spectrograph in the 3100-10400 Å range. We have detected more than 200 emission lines in each region. Physical conditions have been derived using different continuum and line intensity ratios. We have derived He+, C++ and O++ abundances from pure recombination lines as well as collisionally excited lines (CELs) for a large number of ions of different elements. We have obtained consistent estimations of the temperature fluctuation parameter, t2, using different methods. We also report the detection of deuterium Balmer lines up to Dδ (M16) and to Dγ (M20) in the blue wings of the hydrogen lines, which excitation mechanism seems to be continuum fluorescence. The temperature fluctuation paradigm agrees with the results obtained from optical CELs, and the more uncertain ones from far-infrared fine-structure CELs in NGC 3603, although, more observations covering the same volume of the nebula are necessary to obtain solid conclusions.

  20. Insight into Excitement: Balmer-Line Imaging of Evolved Galactic HII Regions

    NASA Astrophysics Data System (ADS)

    Krick, J. E.; Rumstay, K. S.

    1997-12-01

    As part of a long-term investigation into the distribution of dust within evolved galactic HII regions, calibrated H-alpha images have been obtained of the objects M20 (= S30, the Trifid Nebula), S106, and NGC 7538 (= S158). Observations were made with an Axiom/Apogee 2048x2048 CCD camera attached to the 0.9-m telescope operated by the Southeastern Association for Research in Astronomy (SARA) at Kitt Peak National Observatory. Each object was observed with a narrow-band (0.3 nm) H-alpha filter as well as with a 10-nm wide filter centered at 645.7 nm in order to remove the contribution of continuum emission from the H-alpha images. Flux calibration was performed by observation of planetary nebulae for which calibrated spectrophotometry has been published. Comparison of the resulting H-alpha contour maps with published radio continuum maps permits determination of the distribution of obscuring dust within each nebula. Future H-beta observations will be used to prepare contour maps of the reddening within each nebula, which will in turn provide insight into variations of grain properties within HII regions. This research is supported by grants from the National Science Foundation Research Experience for Undergraduates program and from the American Astronomical Society.

  1. A COMPLETE ATLAS OF H I ABSORPTION TOWARD H II REGIONS IN THE SOUTHERN GALACTIC PLANE SURVEY (SGPS I)

    SciTech Connect

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

    2014-04-01

    We present a complete catalog of H I emission and absorption spectrum pairs, toward H II regions, detectable within the boundaries of the Southern Galactic Plane Survey (SGPS I), a total of 252 regions. The catalog is presented in graphical, numerical, and summary formats. We demonstrate an application of this new data set through an investigation of the locus of the Near 3 kpc Arm.

  2. Triggered star formation on the borders of the Galactic Hii region RCW 82

    NASA Astrophysics Data System (ADS)

    Pomarès, M.; Zavagno, A.; Deharveng, L.; Cunningham, M.; Jones, P.; Kurtz, S.; Russeil, D.; Caplan, J.; Comerón, F.

    2009-02-01

    Context: We are engaged in a multi-wavelength study of several Galactic H ii regions that exhibit signposts of triggered star formation on their borders, where the collect and collapse process could be at work. Aims: When addressing the question of triggered star formation, it is critical to ensure the real association between the ionized gas and the neutral material observed nearby. In this paper we stress this point and present CO observations of the RCW 82 star forming region. Methods: The velocity distribution of the molecular gas is combined with the study of young stellar objects (YSOs) detected in the direction of RCW 82. We discuss the YSO's evolutionary status using near- and mid-IR data. The spatial and velocity distributions of the molecular gas are used to discuss the possible scenarios for the star formation around RCW 82. Results: Several massive molecular condensations, together with star formation sites, are observed on the borders of RCW 82. The shapes of the three brightest condensations suggest that they were pre-existent, i.e. not formed through the collect and collapse process. A thin layer of molecular material is observed surrounding the ionized gas, adjacent to the ionization front. This results from the sweeping up of neutral material around the expanding region. Several Class I YSOs are detected in the direction of this layer. Conclusions: The numerous YSOs observed towards the bright molecular condensations bordering (and velocity-associated with) the ionized gas reveal the intense star formation activity in RCW 82. But this region is probably too young to have triggered star formation via the collect and collapse process.

  3. TRIGONOMETRIC PARALLAXES OF MASSIVE STAR-FORMING REGIONS. VI. GALACTIC STRUCTURE, FUNDAMENTAL PARAMETERS, AND NONCIRCULAR MOTIONS

    SciTech Connect

    Reid, M. J.; Sato, M.; Menten, K. M.; Brunthaler, A.; Xu, Y.; Choi, Y. K.; Zheng, X. W.; Zhang, B.; Moscadelli, L.; Honma, M.; Hirota, T.; Hachisuka, K.; Moellenbrock, G. A.; Bartkiewicz, A.

    2009-07-20

    We are using the Very Long Baseline Array and the Japanese VLBI Exploration of Radio Astronomy project to measure trigonometric parallaxes and proper motions of masers found in high-mass star-forming regions across the Milky Way. Early results from 18 sources locate several spiral arms. The Perseus spiral arm has a pitch angle of 16 deg. {+-} 3 deg., which favors four rather than two spiral arms for the Galaxy. Combining positions, distances, proper motions, and radial velocities yields complete three-dimensional kinematic information. We find that star-forming regions on average are orbiting the Galaxy {approx}15 km s{sup -1} slower than expected for circular orbits. By fitting the measurements to a model of the Galaxy, we estimate the distance to the Galactic center R {sub 0} = 8.4 {+-} 0.6 kpc and a circular rotation speed {theta}{sub 0} = 254 {+-} 16 km s{sup -1}. The ratio {theta}{sub 0}/R {sub 0} can be determined to higher accuracy than either parameter individually, and we find it to be 30.3 {+-} 0.9 km s{sup -1} kpc{sup -1}, in good agreement with the angular rotation rate determined from the proper motion of Sgr A*. The data favor a rotation curve for the Galaxy that is nearly flat or slightly rising with Galactocentric distance. Kinematic distances are generally too large, sometimes by factors greater than 2; they can be brought into better agreement with the trigonometric parallaxes by increasing {theta}{sub 0}/R {sub 0} from the IAU recommended value of 25.9 km s{sup -1} kpc{sup -1} to a value near 30 km s{sup -1} kpc{sup -1}. We offer a 'revised' prescription for calculating kinematic distances and their uncertainties, as well as a new approach for defining Galactic coordinates. Finally, our estimates of {theta}{sub 0} and {theta}{sub 0}/R{sub 0}, when coupled with direct estimates of R {sub 0}, provide evidence that the rotation curve of the Milky Way is similar to that of the Andromeda galaxy, suggesting that the dark matter halos of these two

  4. Climatic Effects of Regional Nuclear War

    NASA Technical Reports Server (NTRS)

    Oman, Luke D.

    2011-01-01

    We use a modern climate model and new estimates of smoke generated by fires in contemporary cities to calculate the response of the climate system to a regional nuclear war between emerging third world nuclear powers using 100 Hiroshima-size bombs (less than 0.03% of the explosive yield of the current global nuclear arsenal) on cities in the subtropics. We find significant cooling and reductions of precipitation lasting years, which would impact the global food supply. The climate changes are large and longlasting because the fuel loadings in modern cities are quite high and the subtropical solar insolation heats the resulting smoke cloud and lofts it into the high stratosphere, where removal mechanisms are slow. While the climate changes are less dramatic than found in previous "nuclear winter" simulations of a massive nuclear exchange between the superpowers, because less smoke is emitted, the changes seem to be more persistent because of improvements in representing aerosol processes and microphysical/dynamical interactions, including radiative heating effects, in newer global climate system models. The assumptions and calculations that go into these conclusions will be described.

  5. Evidence for a physical linkage between galactic cosmic rays and regional climate time series

    USGS Publications Warehouse

    Perry, C.A.

    2007-01-01

    The effects of solar variability on regional climate time series were examined using a sequence of physical connections between total solar irradiance (TSI) modulated by galactic cosmic rays (GCRs), and ocean and atmospheric patterns that affect precipitation and streamflow. The solar energy reaching the Earth's surface and its oceans is thought to be controlled through an interaction between TSI and GCRs, which are theorized to ionize the atmosphere and increase cloud formation and its resultant albedo. High (low) GCR flux may promote cloudiness (clear skies) and higher (lower) albedo at the same time that TSI is lowest (highest) in the solar cycle which in turn creates cooler (warmer) ocean temperature anomalies. These anomalies have been shown to affect atmospheric flow patterns and ultimately affect precipitation over the Midwestern United States. This investigation identified a relation among TSI and geomagnetic index aa (GI-AA), and streamflow in the Mississippi River Basin for the period 1878-2004. The GI-AA was used as a proxy for GCRs. The lag time between the solar signal and streamflow in the Mississippi River at St. Louis, Missouri is approximately 34 years. The current drought (1999-2007) in the Mississippi River Basin appears to be caused by a period of lower solar activity that occurred between 1963 and 1977. There appears to be a solar "fingerprint" that can be detected in climatic time series in other regions of the world, with each series having a unique lag time between the solar signal and the hydroclimatic response. A progression of increasing lag times can be spatially linked to the ocean conveyor belt, which may transport the solar signal over a time span of several decades. The lag times for any one region vary slightly and may be linked to the fluctuations in the velocity of the ocean conveyor belt.

  6. Global Famine after a Regional Nuclear War

    NASA Astrophysics Data System (ADS)

    Robock, A.; Xia, L.; Mills, M. J.; Stenke, A.; Helfand, I.

    2014-12-01

    A regional nuclear war between India and Pakistan, using 100 15-kt atomic bombs, could inject 5 Tg of soot into the upper troposphere from fires started in urban and industrial areas. Simulations by three different general circulation models, GISS ModelE, WACCM, and SOCOL, all agree that global surface temperature would decrease by 1 to 2°C for 5 to 10 years, and have major impacts on precipitation and solar radiation reaching Earth's surface. Local summer climate changes over land would be larger. Using the DSSAT crop simulation model forced by these three global climate model simulations, we investigate the impacts on agricultural production in China, the largest grain producer in the world. In the first year after the regional nuclear war, a cooler, drier, and darker environment would reduce annual rice production by 23 Mt (24%), maize production by 41 Mt (23%), and wheat production by 23 Mt (50%). This reduction of food availability would continue, with gradually decreasing amplitude, for more than a decade. Results from simulations in other major grain producing regions produce similar results. Thus a nuclear war using much less than 1% of the current global arsenal could produce a global food crisis and put a billion people at risk of famine.

  7. The Relationship between Luminosity and Broad-Line Region Size in Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Kaspi, Shai; Maoz, Dan; Netzer, Hagai; Peterson, Bradley M.; Vestergaard, Marianne; Jannuzi, Buell T.

    2005-08-01

    We reinvestigate the relationship between the characteristic broad-line region size (RBLR) and the Balmer emission-line, X-ray, UV, and optical continuum luminosities. Our study makes use of the best available determinations of RBLR for a large number of active galactic nuclei (AGNs) from Peterson et al. Using their determinations of RBLR for a large sample of AGNs and two different regression methods, we investigate the robustness of our correlation results as a function of data subsample and regression technique. Although small systematic differences were found depending on the method of analysis, our results are generally consistent. Assuming a power-law relation RBLR~Lα, we find that the mean best-fitting α is about 0.67+/-0.05 for the optical continuum and the broad Hβ luminosity, about 0.56+/-0.05 for the UV continuum luminosity, and about 0.70+/-0.14 for the X-ray luminosity. We also find an intrinsic scatter of ~40% in these relations. The disagreement of our results with the theoretical expected slope of 0.5 indicates that the simple assumption of all AGNs having on average the same ionization parameter, BLR density, column density, and ionizing spectral energy distribution is not valid and there is likely some evolution of a few of these characteristics along the luminosity scale.

  8. Balloon-borne far-infrared spectrophotometry of the galactic center region

    NASA Astrophysics Data System (ADS)

    Drapatz, S.; Haser, L.; Hofmann, R.; Oda, N.; Wilczek, R.

    Far-infrared observations of the galactic center have been carried through with the MPE 1m balloon-borne telescope "Golden Dragon". The measurements are composed of photometric scanning (33 - 95 μm) of the inner 4arcmin×4arcmin and low resolution spectroscopy (Δν = 10 cm-1) of the center and of a position approximately 1.5arcmin to the north. A Mars spectrum has been obtained for calibration. The spatial resolution of the photometry map is increased using the Maximum Entropy Method and the resulting map is compared to other observations in the same and other spectral regions. A clear asymmetry in the ring-like structure around the center indicates the presence of noncircular motions. The shape of the spectra is fairly smooth with at least no prominent dust features. A simple modelling shows a drastic increase of column density within 2 pc from the center and a modest drop over the next 3 pc to the north.

  9. Galactic Cosmic-Ray Intensity Modulation by Corotating Interaction Region Stream Interfaces at 1 au

    NASA Astrophysics Data System (ADS)

    Guo, X.; Florinski, V.

    2016-07-01

    We present a new model that couples galactic cosmic-ray (GCR) propagation with magnetic turbulence transport and the MHD background evolution in the heliosphere. The model is applied to the problem of the formation of corotating interaction regions (CIRs) during the last solar minimum from the period between 2007 and 2009. The numerical model simultaneously calculates the large-scale supersonic solar wind properties and its small-scale turbulent content from 0.3 au to the termination shock. Cosmic rays are then transported through the background, and thus computed, with diffusion coefficients derived from the solar wind turbulent properties, using a stochastic Parker approach. Our results demonstrate that GCR variations depend on the ratio of diffusion coefficients in the fast and slow solar winds. Stream interfaces inside the CIRs always lead to depressions of the GCR intensity. On the other hand, heliospheric current sheet (HCS) crossings do not appreciably affect GCR intensities in the model, which is consistent with the two observations under quiet solar wind conditions. Therefore, variations in diffusion coefficients associated with CIR stream interfaces are more important for GCR propagation than the drift effects of the HCS during a negative solar minimum.

  10. An observation of the Galactic center region with the HEXAGONE high resolution gamma-ray spectrometer

    NASA Technical Reports Server (NTRS)

    Matteson, J.; Pelling, M.; Bowman, B.; Briggs, M.; Gruber, D.; Lingenfelter, R.; Peterson, L.; Lin, R.; Smith, D.; Feffer, P.

    1991-01-01

    The Galactic center region was observed for 6 hours on May 22, 1989 from a high altitude balloon with the HEXAGONE high resolution gamma-ray spectrometer. The instrument had a 285 sq/cm array of cooled germanium detectors with an energy resolution of 2.2 keV at 511 keV and an 18 deg FWHM field of view. The 511 keV gamma-rays from electron-positron annihilation and 1809 keV gamma-rays from the radioactive decay of Al-26 were observed to have fluxes of 8.9 x 10 exp -4 and 1.9 x 10 exp -4 ph/cm-s, respectively. Continuum emission was detected from 20 to 800 keV and preliminary results have been obtained for the spectrum. Below 120 keV this is well described by power law with a slope of -2.6. In the 120-250 keV band the spectrum contains a broad linelike feature. This is interpreted as the result of Compton backscattering of about 511 keV photons from a compact source of electron-positron annihilation radiation.

  11. Extracting the Gamma Ray Signal from Dark Matter Annihilation in the Galactic Center Region

    SciTech Connect

    Dodelson, Scott; Hooper, Dan; Serpico, Pasquale D.

    2007-11-01

    The GLAST satellite mission will study the gamma ray sky with considerably greater exposure than its predecessor EGRET. In addition, it will be capable of measuring the arrival directions of gamma rays with much greater precision. These features each significantly enhance GLAST's potential for identifying gamma rays produced in the annihilations of dark matter particles. The combined use of spectral and angular information, however, is essential if the full sensitivity of GLAST to dark matter is to be exploited. In this paper, we discuss techniques for separating dark matter annihilation products from astrophysical backgrounds, focusing on the Galactic Center region, and perform a forecast for such an analysis. We consider both point-like and diffuse astrophysical backgrounds and model them using a realistic point-spread-function for GLAST. While the results of our study depend on the specific characteristics of the dark matter signal and astrophysical backgrounds, we find that in many scenarios it is possible to successfully identify dark matter annihilation radiation, even in the presence of significant astrophysical backgrounds.

  12. Examining molecular clouds in the Galactic Centre region using X-ray reflection spectra simulations.

    NASA Astrophysics Data System (ADS)

    Walls, M.; Chernyakova, M.; Terrier, R.; Goldwurm, A.

    2016-09-01

    In the centre of our galaxy lies a super-massive black hole, identified with the radio source Sagittarius A⋆. This black hole has an estimated mass of around 4 million solar masses. Although Sagittarius A⋆ is quite dim in terms of total radiated energy, having a luminosity that is a factor of 1010 lower than its Eddington luminosity, there is now compelling evidence that this source was far brighter in the past. Evidence derived from the detection of reflected X-ray emission from the giant molecular clouds in the galactic centre region. However, the interpretation of the reflected emission spectra cannot be done correctly without detailed modelling of the reflection process. Attempts to do so can lead to an incorrect interpretation of the data. In this paper we present the results of a Monte Carlo simulation code we developed in order to fully model the complex processes involved in the emerging reflection spectra. The simulated spectra can be compared to real data in order to derive model parameters and constrain the past activity of the black hole. In particular we apply our code to observations of Sgr B2, in order to constrain the position and density of the cloud and the incident luminosity of the central source. The results of the code have been adapted to be used in Xspec by a large community of astronomers.

  13. Observability of the neutrino flux from the inner region of the galactic disk

    NASA Technical Reports Server (NTRS)

    Silberberg, R.; Shapiro, M. M.; Stecker, F. W.

    1978-01-01

    The observability of galactic neutrinos in a detector of 10 billion tons of water with an observing time of a few years is explored. Although the atmospheric flux exceeds the galactic flux considerably at energies greater than or equal to 1 TeV, the latter may still provide a marginally observable signal owing to its directionality. Galactic muon neutrinos with energy greater than or equal to 1 TeV will produce a signal approximately 2 sigma above the atmospheric background over a four year period. If electron neutrinos can also be studied with the deep underwater muon and neutrino detector, then galactic electron neutrinos above 1 TeV would give an approximate 4 to 5 sigma signal above the electron neutrino background over a four year integration time.

  14. The Fe II Emission in Active Galactic Nuclei: Excitation Mechanisms and Location of the Emitting Region

    NASA Astrophysics Data System (ADS)

    Marinello, M.; Rodríguez-Ardila, A.; Garcia-Rissmann, A.; Sigut, T. A. A.; Pradhan, A. K.

    2016-04-01

    We present a study of Fe ii emission in the near-infrared region (NIR) for 25 active galactic nuclei (AGNs) to obtain information about the excitation mechanisms that power it and the location where it is formed. We employ an NIR Fe ii template derived in the literature and find that it successfully reproduces the observed Fe ii spectrum. The Fe ii bump at 9200 Å detected in all objects studied confirms that Lyα fluorescence is always present in AGNs. The correlation found between the flux of the 9200 Å bump, the 1 μm lines, and the optical Fe ii implies that Lyα fluorescence plays an important role in Fe ii production. We determined that at least 18% of the optical Fe ii is due to this process, while collisional excitation dominates the production of the observed Fe ii. The line profiles of Fe ii λ10502, O i λ11287, Ca ii λ8664, and Paβ were compared to gather information about the most likely location where they are emitted. We found that Fe ii, O i and Ca ii have similar widths and are, on average, 30% narrower than Paβ. Assuming that the clouds emitting the lines are virialized, we show that the Fe ii is emitted in a region twice as far from the central source than Paβ. The distance, though, strongly varies: from 8.5 light-days for NGC 4051 to 198.2 light-days for Mrk 509. Our results reinforce the importance of the Fe ii in the NIR to constrain critical parameters that drive its physics and the underlying AGN kinematics, as well as more accurate models aimed at reproducing this complex emission.

  15. Gamma-ray spectroscopy of the galactic center region: Confirmation of the time-variability of the positron annihilation line

    NASA Technical Reports Server (NTRS)

    Paciesas, W. S.; Cline, T. L.; Teegarden, B. J.; Tueller, J.; Durouchoux, P.; Hameury, J. M.

    1982-01-01

    The GSFC Low-Energy Gamma-Ray Spectrometer observed the region of the galactic center during a balloon flight from Alice Springs, Australia, on 1981 November 20. No significant excess over background was evident in the 511 keV annihilation line. A 98 percent confidence upper limit is derived for this line of 1.2 x .001 photons/sq. cm-s. Continuum emission was detected above 100 keV with a best-fitting power law spectrum.

  16. Time-dependent modulation of galactic cosmic rays by merged interaction regions

    NASA Technical Reports Server (NTRS)

    Perko, J. S.

    1993-01-01

    Models that solve the one-dimensional, solar modulation equation have reproduced the 11-year galactic cosmic ray using functional representations of global merged interaction regions (MIRs). This study extends those results to the solution of the modulation equation with explicit time dependence. The magnetometers on Voyagers 1 and 2 provide local magnetic field intensities at regular intervals, from which one calculates the ratio of the field intensity to the average local field. These ratios in turn are inverted to form diffusion coefficients. Strung together in radius and time, these coefficents then fall and rise with the strength of the interplanetary magnetic field, becoming representations of MIRs. These diffusion coefficients, calculated locally, propagate unchanged from approx. 10 AU to the outer boundary (120 AU). Inside 10 AU, all parameters, including the diffusion coefficient are assumed constant in time and space. The model reproduces the time-intensity profiles of Voyager 2 and Pioneer 10. Radial gradient data from 1982-1990 between Pioneer 10 and Voyager 2 are about the same magnitude as those calculated in the model. It is also shows agreement in rough magnitude with the radial gradient between Pioneer 10 and 1 AU. When coupled with enhanced, time-dependent solar wind speed at the probe's high latitude, as measured by independent observers, the model also follows Voyager 1's time-intensity profile reasonably well, providing a natural source the model also follows Voyager 1's time-intensity profile reasonably well, providing a natural source for the observed negative latitudinal gradients. The model exhibits the 11-year cyclical cosmic ray intensity behavior at all radii, including 1 AU, not just at the location of the spacecraft where the magnetic fields are measured. In addition, the model's point of cosmic ray maximum correctly travels at the solar wind speed, illustrating the well-known propagation of modulation. Finally, at least in the inner

  17. The Fossil Nuclear Outflow in the Central 30 pc of the Galactic Center

    NASA Astrophysics Data System (ADS)

    Hsieh, Pei-Ying; Ho, Paul T. P.; Hwang, Chorng-Yuan; Shimajiri, Yoshito; Matsushita, Satoki; Koch, Patrick M.; Iono, Daisuke

    2016-11-01

    We report a new 1 pc (30″) resolution CS(J=2-1) line map of the central 30 pc of the Galactic center (GC), made with the Nobeyama 45 m telescope. We revisit our previous study of an extraplanar feature called the polar arc (PA), which is a molecular cloud located above SgrA*, with a velocity gradient perpendicular to the galactic plane. We find that the PA can be traced back to the galactic disk. This provides clues to the launching point of the PA, roughly 6 × 106 years ago. Implications of the dynamical timescale of the PA might be related to the Galactic center lobe at parsec scale. Our results suggest that, in the central 30 pc of the GC, the feedback from past explosions could alter the orbital path of molecular gas down to the central tenth of a parsec. In the follow-up work of our new CS(J=2-1) map, we also find that, near systemic velocity, the molecular gas shows an extraplanar hourglass-shaped feature (HG-feature) with a size of ∼13 pc. The latitude-velocity diagrams show that the eastern edge of the HG-feature is associated with an expanding bubble B1, ∼7 pc away from SgrA*. The dynamical timescale of this bubble is ∼3 × 105 years. This bubble is interacting with the 50 km s‑1 cloud. Part of the molecular gas from the 50 km s‑1 cloud was swept away by the bubble to b=-0\\buildrel{\\circ}\\over{.} 2. The western edge of the HG-feature seems to be molecular gas entrained from the 20 km s‑1 cloud toward the north of the galactic disk. Our results suggest a fossil explosion in the central 30 pc of the GC, a few 105 years ago.

  18. Observational studies on the near-infrared unidentified emission bands in galactic H II regions

    SciTech Connect

    Mori, Tamami I.; Onaka, Takashi; Sakon, Itsuki; Ohsawa, Ryou; Bell, Aaron C.; Ishihara, Daisuke; Shimonishi, Takashi

    2014-03-20

    Using a large collection of near-infrared spectra (2.5-5.4 μm) of Galactic H II regions and H II region-like objects, we perform a systematic investigation of astronomical polycyclic aromatic hydrocarbon (PAH) features. Thirty-six objects were observed using the infrared camera on board the AKARI satellite as a part of a director's time program. In addition to the well known 3.3-3.6 μm features, most spectra show a relatively weak emission feature at 5.22 μm with sufficient signal-to-noise ratios, which we identify as the PAH 5.25 μm band (previously reported). By careful analysis, we find good correlations between the 5.25 μm band and both the aromatic hydrocarbon feature at 3.3 μm and the aliphatic hydrocarbon features at around 3.4-3.6 μm. The present results give us convincing evidence that the astronomical 5.25 μm band is associated with C-H vibrations, as suggested by previous studies, and show its potential to probe the PAH size distribution. The analysis also shows that the aliphatic-to-aromatic ratio of I {sub 3.4-3.6} {sub μm}/I {sub 3.3} {sub μm} decreases against the ratio of the 3.7 μm continuum intensity to the 3.3 μm band, I {sub cont,} {sub 3.7} {sub μm}/I {sub 3.3} {sub μm}, which is an indicator of the ionization fraction of PAHs. The midinfrared color of I {sub 9} {sub μm}/I {sub 18} {sub μm} also declines steeply against the ratio of the hydrogen recombination line Brα at 4.05 μm to the 3.3 μm band, I {sub Brα}/I {sub 3.3} {sub μm}. These facts indicate possible dust processing inside or at the boundary of ionized gas.

  19. HOT DIFFUSE EMISSION IN THE NUCLEAR STARBURST REGION OF NGC 2903

    SciTech Connect

    Yukita, Mihoko; Irwin, Jimmy A.; Swartz, Douglas A.; Tennant, Allyn F.; Soria, Roberto

    2012-10-20

    We present a deep Chandra observation of the central regions of the late-type barred spiral galaxy NGC 2903. The Chandra data reveal soft (kT{sub e} {approx} 0.2-0.5 keV) diffuse emission in the nuclear starburst region and extending {approx}2' ({approx}5 kpc) to the north and west of the nucleus. Much of this soft hot gas is likely to be from local active star-forming regions; however, besides the nuclear region, the morphology of hot gas does not strongly correlate with the bar or other known sites of active star formation. The central {approx}650 pc radius starburst zone exhibits much higher surface brightness diffuse emission than the surrounding regions and a harder spectral component in addition to a soft component similar to the surrounding zones. We interpret the hard component as also being of thermal origin with kT{sub e} {approx} 3.6 keV and to be directly associated with a wind fluid produced by supernovae and massive star winds similar to the hard diffuse emission seen in the starburst galaxy M82. The inferred terminal velocity for this hard component, {approx}1100 km s{sup -1}, exceeds the local galaxy escape velocity suggesting a potential outflow into the halo and possibly escape from the galaxy gravitational potential. Morphologically, the softer extended emission from nearby regions does not display an obvious outflow geometry. However, the column density through which the X-rays are transmitted is lower in the zone to the west of the nucleus compared to that from the east and the surface brightness is relatively higher suggesting some of the soft hot gas originates from above the disk: viewed directly from the western zone but through the intervening disk of the host galaxy along sight lines from the eastern zone. There are several point-like sources embedded in the strong diffuse nuclear emission zone. Their X-ray spectra show them to likely be compact binaries. None of these detected point sources are coincident with the mass center of the

  20. Dynamics of Nuclear Regions of Galaxies

    NASA Technical Reports Server (NTRS)

    Miller, Richard H.

    1996-01-01

    Current research carried out with the help of the ASEE-NASA Summer Faculty Program, at NASA-Ames, is concentrated on the dynamics of nuclear regions of galaxies. From a dynamical point of view a galaxy is a collection of around 10(sup 11) stars like our Sun, each of which moves in the summed gravitational field of all the remaining stars. Thus galaxy dynamics becomes a self-consistent n-body problem with forces given by Newtonian gravitation. Strong nonlinearity in the gravitational force and the inherent nonlinearity of self-consistent problems both argue for a numerical approach. The technique of numerical experiments consis of constructing an environment in the computer that is as close as possible to the physical conditions in a real galaxy and then carrying out experiments much like laboratory experiments in physics or engineering, in this environment. Computationally, an experiment is an initial value problem, and a good deal of thought and effort goes into the design of the starting conditions that serve as initial values. Experiments are run at Ames because all the 'equipment' is in place-the programs, the necessary computational power, and good facilities for post-run analysis. Our goal for this research program is to study the nuclear regions in detail and this means replacing most of the galaxy by a suitable boundary condition to allow the full capability of numerical experiments to be brought to bear on a small region perhaps 1/1000 of the linear dimensions of an entire galaxy. This is an extremely delicate numerical problem, one in which some small feature overlook, can easily lead to a collapse or blow-up of the entire system. All particles attract each other in gravitational problems, and the 1/r(sup 2) force is: (1) nonlinear; (2) strong at short range; (3) long-range, and (4) unscreened at any distance.

  1. A Multi-line Study of Atomic Carbon and Carbon Monoxide in the Galactic Star- forming Region W3

    NASA Astrophysics Data System (ADS)

    Jakob, H.; Kramer, C.; Mookerjea, B.; Jeyakumar, S.; Stutzki, J.

    We present results from simultaneous observations of the fine structure line emissions of neutral carbon (C I) at 492 and 809 GHz from selected Galactic star forming regions. These observations include the first results using the the newly installed SMART (SubmilliMeter Array Receiver at Two wavelengths) on KOSMA. The regions observed were selected in order to cover a range of strengths of the incident UV radiation from the exciting star/stars and also densities of the interstellar medium. Extended maps of C I emission from massive star forming regions including W3, S106 and Orion BN/KL have been observed. Simultaneous observation of the two C I lines ensures better relative calibration. The results from these observations will be combined with observed intensities of low-J and mid-J CO and C+ lines and analyzed using radiation transfer based models for Photon Dominated Regions (PDRs).

  2. Voyager 1 observes low-energy galactic cosmic rays in a region depleted of heliospheric ions.

    PubMed

    Stone, E C; Cummings, A C; McDonald, F B; Heikkila, B C; Lal, N; Webber, W R

    2013-07-12

    On 25 August 2012, Voyager 1 was at 122 astronomical units when the steady intensity of low-energy ions it had observed for the previous 6 years suddenly dropped for a third time and soon completely disappeared as the ions streamed away into interstellar space. Although the magnetic field observations indicate that Voyager 1 remained inside the heliosphere, the intensity of cosmic ray nuclei from outside the heliosphere abruptly increased. We report the spectra of galactic cosmic rays down to ~3 × 10(6) electron volts per nucleon, revealing H and He energy spectra with broad peaks from 10 × 10(6) to 40 × 10(6) electron volts per nucleon and an increasing galactic cosmic-ray electron intensity down to ~10 × 10(6) electron volts.

  3. Hydrogen Emission Line n110 rarr n109: Detection at 5009 Megahertz in Galactic H II Regions.

    PubMed

    Höglund, B; Mezger, P G

    1965-10-15

    The hydrogen emission line n(1l0) --> n(109) at the frequency 5009 megahertz which was predicted by Kardashev has been detected in M 17, Orion, and nine other galactic H II regions with the 42.7-m (140-foot) telescope and a 20-channel receiver at the National Radio Astronomy Observatory. The measured product of the half-power width of the line times the ratio of line-to-continuum brightness temperature is larger than that predicted by Kardashev's theory. The radial velocity obtained for M 17 and Orion agrees well with optical measurements. The search for a similar line of excited helium was without success.

  4. XTE J1752-223: a new RXTE and Swift detected X-ray transient in the galactic center region

    NASA Astrophysics Data System (ADS)

    Markwardt, C. B.; Swank, J. H.; Barthelmy, S. D.; Baumgartner, W. H.; Burrows, D. N.; Evans, P. A.; Holland, S. T.; Hoversten, E. A.; Page, K. L.

    2009-10-01

    On 2009-10-23 at 19:55 UT, RXTE discovered a new source while scanning the galactic bulge region, designated XTE J1752-223. Based on the existing PCA scan data, the best fit position is, R.A. = 268.05(16), Dec. = -22.31(4) (J2000), with estimated 95% uncertainty of the final digits shown in parentheses. The 2-10 keV flux of the source at that time was about 30 mCrab. In the past six months, no source has been detected at that position with 95% upper limit of about 1 mCrab.

  5. XMM-Newton observations of the Galactic Centre Region - I. The distribution of low-luminosity X-ray sources

    NASA Astrophysics Data System (ADS)

    Heard, V.; Warwick, R. S.

    2013-02-01

    We exploit XMM-Newton archival data in a study of the extended X-ray emission emanating from Galactic Centre (GC) region. XMM-Newton EPIC-pn and EPIC-MOS observations, with a total exposure time approaching 0.5 and 1 Ms, respectively, were used to create mosaicked images of a 100 pc × 100 pc region centred on Sgr A* in four bands covering the 2-10 keV energy range. We have also constructed a set of narrow-band images corresponding to the neutral iron fluorescence line (Fe i Kα) at 6.4 keV and the K-shell lines at 6.7 and 6.9 keV from helium-like (Fe xxv Kα) and hydrogenic (Fe xxvi Lyα) iron ions. We use a combination of spatial and spectral information to decompose the GC X-ray emission into three distinct components. These comprise: first the emission from hard X-ray emitting unresolved point sources; secondly the reflected continuum and fluorescent line emission from dense molecular material and, thirdly, the soft diffuse emission from thermal plasma in the temperature range kT ≈ 0.8-1.5 keV. We show that the unresolved-source component accounts for the bulk of the 6.7- and 6.9-keV line emission and also makes a major contribution to both the 6.4-keV line emission and the 7.2-10 keV continuum flux. We fit the observed X-ray surface-brightness distribution with an empirical 2D model, which we then compare with a prediction based on an NIR-derived 3D mass model for the old stellar population in the GC. The X-ray surface brightness falls-off more rapidly with angular offset from Sgr A* than the mass-model prediction. One interpretation is that the 2-10 keV X-ray emissivity increases from ≈ 5 × 1027 erg s- 1 M- 1⊙ at 20 arcmin up to almost twice this value at 2 arcmin. Alternatively, some refinement of the mass model may be required, although it is unclear whether this applies to the Nuclear Stellar Cluster, the Nuclear Stellar Disc or a combination of both components. The unresolved hard X-ray emitting source population, on the basis of spectral

  6. Effects of nuclear cross sections at different energies on the radiation hazard from galactic cosmic rays.

    PubMed

    Lin, Z W; Adams, J H

    2007-03-01

    The radiation hazard for astronauts from galactic cosmic rays (GCR) is a major obstacle to long-duration human space exploration. Space radiation transport codes have been developed to calculate the radiation environment on missions to the Moon, Mars, and beyond. We have studied how uncertainties in fragmentation cross sections at different energies affect the accuracy of predictions from such radiation transport calculations. We find that, in deep space, cross sections at energies between 0.3 and 0.85 GeV/nucleon have the largest effect in solar maximum GCR environments. At the International Space Station, cross sections at higher energies have the largest effect due to the geomagnetic cutoff.

  7. 74 MHz nonthermal emission from molecular clouds: evidence for a cosmic ray dominated region at the galactic center.

    PubMed

    Yusef-Zadeh, F; Wardle, M; Lis, D; Viti, S; Brogan, C; Chambers, E; Pound, M; Rickert, M

    2013-10-01

    We present 74 MHz radio continuum observations of the Galactic center region. These measurements show nonthermal radio emission arising from molecular clouds that is unaffected by free–free absorption along the line of sight. We focus on one cloud, G0.13-0.13, representative of the population of molecular clouds that are spatially correlated with steep spectrum (α(327MHz)(74MHz) = 1.3 ± 0.3) nonthermal emission from the Galactic center region. This cloud lies adjacent to the nonthermal radio filaments of the Arc near l 0.2° and is a strong source of 74 MHz continuum, SiO (2-1), and Fe I Kα 6.4 keV line emission. This three-way correlation provides the most compelling evidence yet that relativistic electrons, here traced by 74 MHz emission, are physically associated with the G0.13-0.13 molecular cloud and that low-energy cosmic ray electrons are responsible for the Fe I Kα line emission. The high cosmic ray ionization rate 10(–1)3 s(–1) H(–1) is responsible for heating the molecular gas to high temperatures and allows the disturbed gas to maintain a high-velocity dispersion. Large velocity gradient (LVG) modeling of multitransition SiO observations of this cloud implies H2 densities 10(4–5) cm(–3) and high temperatures. The lower limit to the temperature of G0.13-0.13 is 100 K, whereas the upper limit is as high as 1000 K. Lastly, we used a time-dependent chemical model in which cosmic rays drive the chemistry of the gas to investigate for molecular line diagnostics of cosmic ray heating. When the cloud reaches chemical equilibrium, the abundance ratios of HCN/HNC and N2H+/HCO+ are consistent with measured values. In addition, significant abundance of SiO is predicted in the cosmic ray dominated region of the Galactic center. We discuss different possibilities to account for the origin of widespread SiO emission detected from Galactic center molecular clouds.

  8. THE WMAP HAZE FROM THE GALACTIC CENTER REGION DUE TO MASSIVE STAR EXPLOSIONS AND A REDUCED COSMIC RAY SCALE HEIGHT

    SciTech Connect

    Biermann, Peter L.; Becker, Julia K.; Caceres, Gabriel; Meli, Athina; Seo, Eun-Suk; Stanev, Todor

    2010-02-10

    One important prediction of acceleration of particles in the supernova caused shock in the magnetic wind of exploding Wolf-Rayet and red supergiant stars is the production of an energetic particle component with an E {sup -2} spectrum at a level on the order of 1% of the full cosmic ray electron population. After allowing for transport effects, so steepening the spectrum to E {sup -7/3}, this component as cosmic ray electrons readily explains the WMAP haze from the Galactic center region in spectrum, intensity, and radial profile; this requires the diffusion timescale for cosmic rays in the Galactic center region to be much shorter than in the solar neighborhood: the energy for cosmic ray electrons at the transition between diffusion dominance and loss dominance is shifted to considerably higher particle energy. We predict that more precise observations will find a radio spectrum of {nu}{sup -2/3}, at higher frequencies {nu}{sup -1}, and at yet higher frequencies finally {nu}{sup -3/2}.

  9. VizieR Online Data Catalog: G5 and later stars in a North Galactic Pole region (Upgren 1962)

    NASA Astrophysics Data System (ADS)

    Upgren, A. R., Jr.

    2015-11-01

    The catalog is an objective-prism survey of late-type stars in a region of 396 square degrees surrounding the north galactic pole. The objective-prism spectra employed have a dispersion of 58 nm/mm at H-γ and extend into the ultraviolet region. The catalog contains the magnitudes and spectral classes of 4027 stars of class G5 and later, complete to a limiting photographic magnitude of 13.0. The spectral classification of the stars is based on the Yerkes system. The catalog includes the serial numbers of the stars corresponding to the numbers on the identification charts in Upgren (1984), BD and HD numbers, B magnitudes, spectral classes, and letters designating the subregion and identification chart on which each star is located. This survey was undertaken to determine the space densities at varying distances from the galactic plane. Accurate separation of the surveyed stars of G5 and later into giants and dwarfs was achieved through the use of the UV region as well as conventional methods of classification. The resulting catalog of 4027 stars is probably complete over the region to a limiting photographic magnitude of 13.0. The region covered by the survey is the same as that discussed by Slettebak and Stock (1959) and is in the approximate range RA 11:30 to 13:00, Declination +25 to +50 (B1950.0). The catalog includes all M and Carbon stars previously published by Upgren (1960). For a discussion of the classification criteria, the combining of multiple classifications (each spectral image was classified twice), the determination of magnitudes, and additional details about the catalog, the source reference should be consulted. Corrections, accurate positions, more identifications, and remarks have been added in Nov. 2015 by B. Skiff in the file "positions.dat"; see the "History" section below for details. (3 data files).

  10. Effects of Nuclear Cross Sections at Different Energies on the Radiation Hazard from Galactic Cosmic Rays

    NASA Technical Reports Server (NTRS)

    Lin, Z. W.; Adams, J. H., Jr.

    2006-01-01

    The radiation hazard for astronauts from galactic cosmic rays is a major obstacle in long duration human space explorations. Space radiation transport codes have been developed to calculate radiation environment on missions to the Moon, Mars or beyond. We have studied how uncertainties in fragmentation cross sections at different energies affect the accuracy of predictions from such radiation transport. We find that, in deep space, cross sections between 0.3 and 0.85 GeV/u usually have the largest effect on dose-equivalent behind shielding in solar minimum GCR environments, and cross sections between 0.85 and 1.2 GeV/u have the largest effect in solar maximum GCR environments. At the International Space Station, cross sections at higher energies have the largest effect due to the geomagnetic cutoff.

  11. Effects of nuclear cross sections at different energies on the radiation hazard from galactic cosmic rays.

    PubMed

    Lin, Z W; Adams, J H

    2007-03-01

    The radiation hazard for astronauts from galactic cosmic rays (GCR) is a major obstacle to long-duration human space exploration. Space radiation transport codes have been developed to calculate the radiation environment on missions to the Moon, Mars, and beyond. We have studied how uncertainties in fragmentation cross sections at different energies affect the accuracy of predictions from such radiation transport calculations. We find that, in deep space, cross sections at energies between 0.3 and 0.85 GeV/nucleon have the largest effect in solar maximum GCR environments. At the International Space Station, cross sections at higher energies have the largest effect due to the geomagnetic cutoff. PMID:17316078

  12. Determining inclinations of active galactic nuclei via their narrow-line region kinematics. II. Correlation with observed properties

    SciTech Connect

    Fischer, T. C.; Crenshaw, D. M.; Kraemer, S. B.; Schmitt, H. R.; Turner, T. J.

    2014-04-10

    Active galactic nuclei (AGNs) are axisymmetric systems to first order; their observed properties are likely strong functions of inclination with respect to our line of sight, yet the specific inclinations of all but a few AGNs are generally unknown. By determining the inclinations and geometries of nearby Seyfert galaxies using the kinematics of their narrow-line regions (NLRs) and comparing them with observed properties, we find strong correlations between inclination and total hydrogen column density, infrared color, and Hβ FWHM. These correlations provide evidence that the orientation of AGNs with respect to our line of sight affects how we perceive them beyond the Seyfert 1/2 dichotomy. They can also be used to constrain three-dimensional models of AGN components such as the broad-line region and torus. Additionally, we find weak correlations between AGN luminosity and several modeled NLR parameters, which suggests that the NLR geometry and kinematics are dependent to some degree on the AGN's radiation field.

  13. Nuclear planetology: understanding habitable planets as Galactic bulge stellar remnants (black dwarfs) in a Hertzsprung-Russell (HR) diagram

    NASA Astrophysics Data System (ADS)

    Roller, Goetz

    2016-04-01

    model constraining the evolution of a rocky planet like Earth or Mercury from a stellar precursor of the oldest population to a Fe-C BLD, shifting through different spectral classes in a HR diagram after massive decompression and tremendous energy losses. In the light of WD/BLD cosmochronology [1], solar system bodies like Earth, Mercury and Moon are regarded as captured interlopers from the Galactic bulge, Earth and Moon possibly representing remnants of an old binary system. Such a preliminary scenario is supported by similar ages obtained from WD's for the Galactic halo [1] and, independently, by means of 187Re-232Th-238U nuclear geochronometry [2, 4, 5], together with recent observations extremely metal-poor stars from the cosmic dawn in the bulge of the Milky Way [6]. This might be further elucidated in the near future by Th/U cosmochronometry based upon a nuclear production ratio Th/U = 0.96 [5] and additionally by means of a newly developed nucleogeochronometric age dating method for stellar spectroscopy, which will be presented in a forthcoming paper. The model shall stimulate geochemical data interpretation from a different perspective to constrain the (thermal) evolution of a habitable planet as to its geo-, bio-, hydro- and atmosphere. [1] Fontaine et al. (2001), Public. Astron. Soc. of the Pacific 113, 409-435. [2] Roller (2015), Abstract T34B-0407, AGU Spring Meeting 2015. [3] Arevalo et al. (2010), Chem. Geol. 271, 70-85. [4] Roller (2015), Geophys. Res. Abstr. 17, EGU2015-2399. [5] Roller (2015), 78th Annu. Meeting Met. Soc., Abstract #5041. [6] Howes et al. (2015), Nature 527, 484-487.

  14. Line and continuum radiation from the outer region of accretion discs in active galactic nuclei. I - Preliminary considerations

    NASA Astrophysics Data System (ADS)

    Collin-Souffrin, S.

    1987-06-01

    The structure and emission of the optically thin region of steady accretion discs in Active Galactic Nuclei (AGN) is investigated. It is shown that this region is located far from the center (R/RG very large 102). If its only energy source is provided by accretion, the temperature is very low (1000 - 2000K) and therefore it cannot be identified with the broad line emitting region (BLR). The overall emission of the optically thin region is negligible, except in the infrared at a few microns, where it gives some contribution of the "5 μ-bump". However it is found that, if the disc is heated by the down scattered part of the non-thermal continuum observed in AGN, the physical parameters of the optically thin region satisfy the requirements of photoionization models for the line emission. Hard X-ray heating of the external regions of accretion discs is the source of the "missing energy" in the budget of the BLR (Collin-Souffrin, 1986) and moreover gives rise to an intense infrared thermal continuum able to account for the 5 μ bump. Finally this model could solve the "Fell problem".

  15. Ice Mapping Observations in Galactic Star-Forming Regions: the AKARI Legacy

    NASA Astrophysics Data System (ADS)

    Fraser, Helen Jane; Suutarinnen, Aleksi; Noble, Jennifer

    2015-08-01

    It is becoming increasingly clear that explaining the small-scale distribution of many gas-phase molecules relies on our interpretation of the complex inter-connectivity between gas- and solid-phase interstellar chemistries. Inputs to proto-stellar astrochemical models are required that exploit ice compositions reflecting the historical physical conditions in pre-stellar environments when the ices first formed. Such data are required to translate the near-universe picture of ice-composition to our understanding of the role of extra-galactic ices in star-formation at higher redshifts.Here we present the first attempts at multi-object ice detections, and the subsequent ice column density mapping. The AKARI space telescope was uniquely capable of observing all the ice features between 2 and 5 microns, thereby detecting H2O, CO and CO2 ices concurrently, through their stretching vibrational features. Our group has successfully extracted an unprecedented volume of ice spectra from AKARI, including sources with not more than 2 mJy flux at 3 microns, showing:(a) H2O CO and CO2 ices on 30 lines of sight towards pre-stellar and star-forming cores, which when combined with laboratory experiments indicate how the chemistries of these three ices are interlinked (Noble et al (2013)),(b) ice maps showing the spatial distribution of water ice across 12 pre-stellar cores, in different molecular clouds (Suutarinnen et al (2015)), and the distribution of ice components within these cores on 1000 AU scales (Noble et al (2015)),(c) over 200 new detections of water ice, mostly on lines of sight towards background sources (> 145), indicating that water ice column density has a minimum value as a function of Av, but on a cloud-by-cloud basis typically correlates with Av, and dust emissivity at 250 microns (Suutarinnen et al (2015)),(d) the first detections of HDO ice towards background stars (Fraser et al (2015)).We discuss whether these results support the picture of a generic chemical

  16. Investigating Molecular Inheritance of Carbon in Star-forming Regions along a Galactic Gradient

    NASA Astrophysics Data System (ADS)

    Smith, Rachel L.; Blake, Geoffrey; Boogert, Adwin; Pontoppidan, Klaus Martin; Lockwood, Alexandra C.

    2015-08-01

    Observations of CO isotopologues taken at high spectral resolution toward young stellar objects (YSOs) are valuable tools for investigating protoplanetary chemical reservoirs, and enable robust comparisons between YSOs and solar system material (meteorites and the Sun). Investigating a range of YSO environments also helps parameterize variations in the distribution and evolution of carbon-based molecules, furthering an understanding of prebiotic chemistry. We have begun a wide survey of massive YSOs using Keck-NIRSPEC at high spectral resolution (R=25,000). Fundamental and first-overtone near-IR CO rovibrational absorption spectra have thus far been obtained toward 14 massive, luminous YSOs at Galactocentric radii (RGC) ranging from ~4.5 to 9.7 kpc. From these data we can obtain precise [12CO]/[13CO] gas-phase abundance ratios along a Galactic gradient, and [12CO]/[13CO]Gas can be further evaluated against published [12CO2]/[13CO2]Ice and [12CO]/[13CO]Ice because all observations are in absorption, a robust study of molecular inheritance is possible by virtue of comparing 12C/13C along the same lines-of-sight. Initial results for cold CO gas at RGC ~ 6.1 kpc and 9.4 kpc reveal [12C16O]/[13C16O] of 59+/-8 and 74+/-3, respectively, roughly following an expected 12C/13C Galactic gradient. Thus far, we find [12CO]/[13CO] in the cold CO gas to be lower than [12CO2]/[13CO2]Ice, suggesting that CO2 may not originate from CO reservoirs as often assumed. While very high-resolution observations of CO gas toward low-mass YSOs observed with VLT-CRIRES show significant heterogeneity in [12CO]/[13CO] at RGC ~ 8 kpc, this dispersion is not found for the massive YSOs. Both the low-mass and massive YSOs have higher [12CO]/[13CO] in warm vs. cold gas, and both show signatures suggesting possible interplay between CO ice and gas reservoirs. Overall, our results indicate that carbon isotopic evolution in massive YSO environments may follow different paths compared to low-mass YSOs

  17. ISOLATED WOLF-RAYET STARS AND O SUPERGIANTS IN THE GALACTIC CENTER REGION IDENTIFIED VIA PASCHEN-{alpha} EXCESS

    SciTech Connect

    Mauerhan, J. C.; Stolovy, S. R.; Cotera, A.; Dong, H.; Wang, Q. D.; Morris, M. R.; Lang, C.

    2010-12-10

    We report the discovery of 19 hot, evolved, massive stars near the Galactic center region (GCR). These objects were selected for spectroscopy owing to their detection as strong sources of Paschen-{alpha} (P{alpha}) emission-line excess, following a narrowband imaging survey of the central 0.{sup 0}65 x 0.{sup 0}25 (l, b) around Sgr A* with the Hubble Space Telescope. Discoveries include six carbon-type (WC) and five nitrogen-type (WN) Wolf-Rayet stars, six O supergiants, and two B supergiants. Two of the O supergiants have X-ray counterparts having properties consistent with solitary O stars and colliding-wind binaries. The infrared photometry of 17 stars is consistent with the Galactic center distance, but 2 of them are located in the foreground. Several WC stars exhibit a relatively large infrared excess, which is possibly thermal emission from hot dust. Most of the stars appear scattered throughout the GCR, with no relation to the three known massive young clusters; several others lie near the Arches and Quintuplet clusters and may have originated within one of these systems. The results of this work bring the total sample of Wolf-Rayet (WR) stars in the GCR to 88. All sources of strong P{alpha} excess have been identified in the area surveyed with HST, which implies that the sample of WN stars in this region is near completion, and is dominated by late (WNL) types. The current WC sample, although probably not complete, is almost exclusively dominated by late (WCL) types. The observed WR subtype distribution in the GCR is a reflection of the intrinsic rarity of early subtypes (WNE and WCE) in the inner Galaxy, an effect that is driven by metallicity.

  18. H I ABSORPTION TOWARD H II REGIONS AT SMALL GALACTIC LONGITUDES

    SciTech Connect

    Jones, C.; Dickey, J. M.; Dawson, J. R.; McClure-Griffiths, N. M.; Anderson, L. D.; Bania, T. M.

    2013-09-10

    We make a comprehensive study of H I absorption toward H II regions located within |l| < 10 Degree-Sign . Structures in the extreme inner Galaxy are traced using the longitude-velocity space distribution of this absorption. We find significant H I absorption associated with the Near and Far 3 kpc Arms, the Connecting Arm, Bania's Clump 1, and the H I Tilted Disk. We also constrain the line-of-sight distances to H II regions, by using H I absorption spectra together with the H II region velocities measured by radio recombination lines.

  19. 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).

  20. A RAPIDLY EVOLVING REGION IN THE GALACTIC CENTER: WHY S-STARS THERMALIZE AND MORE MASSIVE STARS ARE MISSING

    SciTech Connect

    Chen, Xian; Amaro-Seoane, Pau E-mail: Pau.Amaro-Seoane@aei.mpg.de

    2014-05-10

    The existence of ''S-stars'' within a distance of 1'' from Sgr A* contradicts our understanding of star formation, due to Sgr A* 's forbiddingly violent environment. A suggested possibility is that they form far away and were brought in by some fast dynamical process, since they are young. Nonetheless, all conjectured mechanisms either fail to reproduce their eccentricities—without violating their young age—or cannot explain the problem of {sup i}nverse mass segregation{sup :} the fact that lighter stars (the S-stars) are closer to Sgr A* and more massive ones, Wolf-Rayet (WR) and O-stars, are farther out. In this Letter we propose that the mechanism responsible for both the distribution of the eccentricities and the paucity of massive stars is the Kozai-Lidov-like resonance induced by a sub-parsec disk recently discovered in the Galactic center. Considering that the disk probably extended to a smaller radius in the past, we show that in as short as (a few) 10{sup 6} yr, the stars populating the innermost 1'' region would redistribute in angular-momentum space and recover the observed ''super-thermal'' distribution. Meanwhile, WR and O-stars in the same region intermittently attain ample eccentricities that will lead to their tidal disruptions by the central massive black hole. Our results provide new evidences that Sgr A* was powered several millions years ago by an accretion disk as well as by tidal stellar disruptions.

  1. GALACTIC ALL-SKY SURVEY HIGH-VELOCITY CLOUDS IN THE REGION OF THE MAGELLANIC LEADING ARM

    SciTech Connect

    For, Bi-Qing; Staveley-Smith, Lister; McClure-Griffiths, N. M.

    2013-02-10

    We present a catalog of high-velocity clouds in the region of the Magellanic Leading Arm. The catalog is based on neutral hydrogen (H I) observations from the Parkes Galactic All-Sky Survey. Excellent spectral resolution allows clouds with narrow-line components to be resolved. The total number of detected clouds is 419. We describe the method of cataloging and present the basic parameters of the clouds. We discuss the general distribution of the high-velocity clouds and classify the clouds based on their morphological type. The presence of a significant number of head-tail clouds and their distribution in the region is discussed in the context of Magellanic System simulations. We suggest that ram-pressure stripping is a more important factor than tidal forces for the morphology and formation of the Magellanic Leading Arm and that different environmental conditions might explain the morphological difference between the Magellanic Leading Arm and Magellanic Stream. We also discuss a newly identified population of clouds that forms the LA IV and a new diffuse bridge-like feature connecting the LA II and III complexes.

  2. Understanding active galactic nuclei: peeling the onion.

    NASA Astrophysics Data System (ADS)

    Krolik, J. H.

    A brief review is presented of selected current problems in understanding active galactic nuclei, with special emphasis on the contributions that X-ray observations can make. Questions having to do with: how the character of the host galaxy influences nuclear activity; emission line regions; the border between the nucleus and the stellar portion of the active galaxy; radiation of the nonthermal continuum; and the possible existence of an accretion disk are touched upon.

  3. The stellar content of the nuclear regions of Sc galaxies

    NASA Technical Reports Server (NTRS)

    Turnrose, B. E.

    1976-01-01

    Stellar-population syntheses based on absolute spectral energy distributions over the wavelength range from 3300 to 10,400 A are used to determine the stellar content of the nuclear regions of seven nearby Sc galaxies (NGC 628, 1073, 1084, 1637, 2903, 4321, and 5194). A linear-programming procedure is employed to construct models of the overall stellar populations whose spectra closely match those of the seven galaxies. Absolute measurements of the emission-line spectra of the nuclear regions are also provided. It is found that: (1) intrinsic reddening is probably present in each nuclear region; (2) the upper main sequence is substantially populated in most of the models; (3) the lower main sequence contributes insignificantly to the luminosity in all optimal solutions; (4) substantial contributions are made by evolved M stars at long wavelengths in all the models; (5) the model photometric M/L ratios are low, of the order of unity; and (6) the O-B stars arising naturally in the population models are just sufficient to provide the observed nuclear ionization in all the galaxies except NGC 5194, which may be collisionally ionized. The properties of the nuclear regions are shown to be consistent with the existence of a common initial mass function for star formation and a variety of time dependences for the star-formation process. A possibly significant correlation is noted between nuclear stellar content and overall dynamical properties in four of the galaxies.

  4. The inner regions of the spiral galaxy NGC 3310 - Evidence for galactic cannibalism

    NASA Astrophysics Data System (ADS)

    Balick, B.; Heckman, T.

    1981-03-01

    High resolution optical and radio images of the inner regions of NGC 3310 are presented. Subtle but important differences exist in the distributions of the stellar continuum on the one hand and the ionized gas and high energy particles on the other. These data and others suggest that a galaxy-galaxy collision has lead to a major disruption in the inner regions which has not yet fully relaxed even at radii of 0.5-1 kpc where the relaxation time scales are only 10 to the power 7.8 yr. An encounter in which an Irr 1 galaxy is being cannibalized by NGC 3110 provides a scenario for the recent history of the galaxy which is in accord with published observations.

  5. 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).

  6. Kinematics of the nuclear region of M83

    NASA Astrophysics Data System (ADS)

    Rodrigues, I.; Díaz, R. J.; Dottori, H.; Mediavilla, E.; Agüero, M. P.; Mast, D.

    2006-06-01

    The enormous energy output detected in many cores of galaxies is one of the key issues in the studies of galaxies and their evolution, notwithstanding several questions remain unsolved: Are accretion onto super-massive black holes and violent star formation just coevolving phenomena or necessary partners of the activity? How is the detailed physics of the mechanisms triggering the nuclear extended violent star formation? Which is the relationship of the triggering mechanisms with galaxy evolution? The main drawback to face these issues is that developed stages of large star formation events at galactic centres do not provide enough clues about their origin, since the morphological signatures of the triggering mechanism are smeared out in the time scale of a few orbital revolutions of the galaxy core. Here we present the onset of such an event undergone by M83, a galaxy nearby enough to allow detailed spatial cinematic and morphological studies. High resolution 3D near-IR spectroscopy sugests the capture of a satellite galaxy, whose spur left behind a giant nuclear arc of violent star formation. The age gradient within the arc supports that this structure traces the orbital path of the intruder. Our numerical modelling indicates that the two nuclei would coalesce in less than 50 Myr.

  7. Galactic cosmic rays and nucleosynthesis

    SciTech Connect

    Kiener, Juergen

    2010-03-01

    The nucleosynthesis of the light elements Li, Be and B by galactic cosmic rays is presented. Observations of cosmic rays and the nuclear reactions responsible for Li, Be and B nucleosynthesis are described, followed by some words on propagation. At the end, some open questions concerning galactic cosmic rays are discussed.

  8. Discovery in the Galactic Bulge

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2015-11-01

    In our efforts to map our galaxys structure, one region has remained very difficult to probe: the galactic center. A new survey, however, uses infrared light to peer through the gas and dust in the galactic plane, searching for variable stars in the bulge of the galaxy. This study has discovered a population of very young stars in a thin disk in the galactic center, providing clues to the star formation history of the Milky Way over the last 100 million years.Obscured CenterThe center of the Milky Way is dominated by a region known as the galactic bulge. Efforts to better understand this region in particular, its star formation history have been hindered by the stars, gas, and dust of the galactic disk, which prevent us from viewing the galactic bulge at low latitudes in visible light.The positions of the 35 classical Cepheids discovered in VVV data, projected onto an image of the galactic plane. Click for a better look! The survey area is bounded by the blue lines, and the galactic bar is marked with a red curve. The bottom panel shows the position of the Cepheids overlaid on the VVV bulge extinction map. [Dkny et al. 2015]Infrared light, however, can be used to probe deeper through the dust than visible-light searches. A new survey called VISTA Variables in the Via Lactea (VVV) uses the VISTA telescope in Chile to search, in infrared, for variable stars in the inner part of the galaxy. The VVV survey area spans the Milky Way bulge and an adjacent section of the mid-plane where star formation activity is high.Led by Istvn Dkny, a researcher at the Millennium Institute of Astrophysics and the Pontifical Catholic University of Chile, a team has now used VVV data to specifically identify classical Cepheid variable stars in the bulge. Why? Cepheids are pulsating stars with a very useful relation between their periods and luminosities that allows them to be used as distance indicators. Moreover, classical Cepheids are indicators of young stellar populations which can

  9. Massive Star Formation of the SGR a East H (sub II) Regions Near the Galactic Center

    NASA Technical Reports Server (NTRS)

    Yusef-Zadeh, F.; Lacy, J. H.; Wardle, M.; Whitney, B.; Bushouse, H.; Roberts, D. A.; Arendt, R. G.

    2010-01-01

    A group of four compact H II regions associated with the well-known 50 km/s molecular cloud is the closest site of on-going star formation to the dynamical center of the Galaxy, at a projected distance of approximately 6 pc. We present a study of ionized gas based on the [Ne II] (12.8 micron) line, as well as multi-frequency radio continuum, Hubble Space Telescope Pa alpha, and Spitzer Infrared Array Camera observations of the most compact member of the H II group, Sgr A East H II D. The radio continuum image at 6 cm shows that this source breaks up into two equally bright ionized features, D1 and D2. The spectral energy distribution of the D source is consistent with it being due to a 25 =/- 3 solar mass star with a luminosity of 8 +/- 3 x 10(exp 4) Solar luminosity . The inferred mass, effective temperature of the UV source, and the ionization rate are compatible with a young O9-B0 star. The ionized features D1 and D2 are considered to be ionized by UV radiation collimated by an accretion disk. We consider that the central massive star photoevaporates its circumstellar disk on a timescale of 3x (exp 4) years giving a mass flux approximately 3 x 10(exp -5) Solar Mass / year and producing the ionized material in D1 and D2 expanding in an inhomogeneous medium. The ionized gas kinematics, as traced by the [Ne II] emission, is difficult to interpret, but it could be explained by the interaction of a bipolar jet with surrounding gas along with what appears to be a conical wall of lower velocity gas. The other H II regions, Sgr A East A-C, have morphologies and kinematics that more closely resemble cometary flows seen in other compact H II regions, where gas moves along a paraboloidal surface formed by the interaction of a stellar wind with a molecular cloud.

  10. MASSIVE STAR FORMATION OF THE SGR A EAST H II REGIONS NEAR THE GALACTIC CENTER

    SciTech Connect

    Yusef-Zadeh, F.; Lacy, J. H.; Wardle, M.; Whitney, B.; Bushouse, H.; Roberts, D. A.; Arendt, R. G.

    2010-12-20

    A group of four compact H II regions associated with the well-known 50 km s{sup -1} molecular cloud is the closest site of on-going star formation to the dynamical center of the Galaxy, at a projected distance of {approx}6 pc. We present a study of ionized gas based on the [Ne II] (12.8 {mu}m) line, as well as multi-frequency radio continuum, Hubble Space Telescope Pa{alpha}, and Spitzer Infrared Array Camera observations of the most compact member of the H II group, Sgr A East H II D. The radio continuum image at 6 cm shows that this source breaks up into two equally bright ionized features, D1 and D2. The spectral energy distribution of the D source is consistent with it being due to a 25 {+-} 3 M{sub sun} star with a luminosity of 8 {+-} 3 x 10{sup 4} L{sub sun}. The inferred mass, effective temperature of the UV source, and the ionization rate are compatible with a young O9-B0 star. The ionized features D1 and D2 are considered to be ionized by UV radiation collimated by an accretion disk. We consider that the central massive star photoevaporates its circumstellar disk on a timescale of 3 x 10{sup 4} years giving a mass flux {approx}3 x 10{sup -5} M{sub sun} yr{sup -1} and producing the ionized material in D1 and D2 expanding in an inhomogeneous medium. The ionized gas kinematics, as traced by the [Ne II] emission, is difficult to interpret, but it could be explained by the interaction of a bipolar jet with surrounding gas along with what appears to be a conical wall of lower velocity gas. The other H II regions, Sgr A East A-C, have morphologies and kinematics that more closely resemble cometary flows seen in other compact H II regions, where gas moves along a paraboloidal surface formed by the interaction of a stellar wind with a molecular cloud.

  11. Young open clusters in the Galactic star forming region NGC 6357

    NASA Astrophysics Data System (ADS)

    Massi, F.; Giannetti, A.; Di Carlo, E.; Brand, J.; Beltrán, M. T.; Marconi, G.

    2015-01-01

    Context. NGC 6357 is an active star forming region with very young massive open clusters. These clusters contain some of the most massive stars in the Galaxy and strongly interact with nearby giant molecular clouds. Aims: We study the young stellar populations of the region and of the open cluster Pismis 24, focusing on their relationship with the nearby giant molecular clouds. We seek evidence of triggered star formation "propagating" from the clusters. Methods: We used new deep JHKs photometry, along with unpublished deep Spitzer/IRAC mid-infrared photometry, complemented with optical HST/WFPC2 high spatial resolution photometry and X-ray Chandra observations, to constrain age, initial mass function, and star formation modes in progress. We carefully examine and discuss all sources of bias (saturation, confusion, different sensitivities, extinction). Results: NGC 6357 hosts three large young stellar clusters, of which Pismis 24 is the most prominent. We found that Pismis 24 is a very young (~1-3 Myr) open cluster with a Salpeter-like initial mass function and a few thousand members. A comparison between optical and infrared photometry indicates that the fraction of members with a near-infrared excess (i.e., with a circumstellar disk) is in the range 0.3-0.6, consistent with its photometrically derived age. We also find that Pismis 24 is likely subdivided into a few different subclusters, one of which contains almost all the massive members. There are indications of current star formation triggered by these massive stars, but clear age trends could not be derived (although the fraction of stars with a near-infrared excess does increase towards the Hii region associated with the cluster). The gas out of which Pismis 24 formed must have been distributed in dense clumps within a cloud of less dense gas ~1 pc in radius. Conclusions: Our findings provide some new insight into how young stellar populations and massive stars emerge, and evolve in the first few Myr after

  12. Effects of the Stellar Component on Derived Physical Parameters of Galactic H II Regions

    NASA Astrophysics Data System (ADS)

    Robledo-Rella, V.

    2000-05-01

    We present results of long-slit spatially integrated (~ 7 arcmin2) spectroscopy (3600 - 10200 Å in the central regions of Carina, M8 and M20. We obtained two types of spectra: neb \\ (pure nebular) and all \\ (nebular plus stellar). The stellar effect increases along the Balmer series, with neb/all \\ ~ 1.20 at Hdelta, but could be much stronger (~ 1.7) for weaker lines beyond H8. The resulting neb \\ dereddened spectra give slightly higher electron temperatures which yield (O/H) smaller (~ 0.10-0.30 dex), (N/H) higher (~ 0.05-0.10 dex), (Ne/H) smaller (~ 0.25-0.40 dex), and (Ar/H) smaller (~ 0.15-0.30 dex), with respect to the all \\ case. Although these differences are roughly within the uncertainties, they could be important in deriving accurate chemical compositions in extragalactic nebula where the stars are not resolved.

  13. OUTFLOWS FROM ACTIVE GALACTIC NUCLEI: KINEMATICS OF THE NARROW-LINE AND CORONAL-LINE REGIONS IN SEYFERT GALAXIES

    SciTech Connect

    Mueller-Sanchez, F.; Prieto, M. A.; Vives-Arias, H.; Davies, R. I.; Tacconi, L. J.; Genzel, R.; Malkan, M.

    2011-10-01

    As part of an extensive study of the physical properties of active galactic nuclei (AGNs) we report high spatial resolution near-IR integral-field spectroscopy of the narrow-line region (NLR) and coronal-line region (CLR) of seven Seyfert galaxies. These measurements elucidate for the first time the two-dimensional spatial distribution and kinematics of the recombination line Br{gamma} and high-ionization lines [Si VI], [Al IX], and [Ca VIII] on scales <300 pc from the AGN. The observations reveal kinematic signatures of rotation and outflow in the NLR and CLR. The spatially resolved kinematics can be modeled as a combination of an outflow bicone and a rotating disk coincident with the molecular gas. High-excitation emission is seen in both components, suggesting it is leaking out of a clumpy torus. While NGC 1068 (Seyfert 2) is viewed nearly edge-on, intermediate-type Seyferts are viewed at intermediate angles, consistent with unified schemes. A correlation between the outflow velocity and the molecular gas mass in r < 30 pc indicates that the accumulation of gas around the AGN increases the collimation and velocity of the outflow. The outflow rate is 2-3 orders of magnitude greater than the accretion rate, implying that the outflow is mass loaded by the surrounding interstellar medium (ISM). In half of the observed AGNs, the kinetic power of the outflow is of the order of the power required by two-stage feedback models to be thermally coupled to the ISM and to match the M{sub BH}-{sigma}* relation. In these objects, the radio jet is clearly interacting with the ISM, indicative of a link between jet power and outflow power.

  14. NuSTAR Hard X-Ray Survey of the Galactic Center Region. II. X-Ray Point Sources

    NASA Astrophysics Data System (ADS)

    Hong, JaeSub; Mori, Kaya; Hailey, Charles J.; Nynka, Melania; Zhang, Shuo; Gotthelf, Eric; Fornasini, Francesca M.; Krivonos, Roman; Bauer, Franz; Perez, Kerstin; Tomsick, John A.; Bodaghee, Arash; Chiu, Jeng-Lun; Clavel, Maïca; Stern, Daniel; Grindlay, Jonathan E.; Alexander, David M.; Aramaki, Tsuguo; Baganoff, Frederick K.; Barret, Didier; Barrière, Nicolas; Boggs, Steven E.; Canipe, Alicia M.; Christensen, Finn E.; Craig, William W.; Desai, Meera A.; Forster, Karl; Giommi, Paolo; Grefenstette, Brian W.; Harrison, Fiona A.; Hong, Dooran; Hornstrup, Allan; Kitaguchi, Takao; Koglin, Jason E.; Madsen, Kristen K.; Mao, Peter H.; Miyasaka, Hiromasa; Perri, Matteo; Pivovaroff, Michael J.; Puccetti, Simonetta; Rana, Vikram; Westergaard, Niels J.; Zhang, William W.; Zoglauer, Andreas

    2016-07-01

    We present the first survey results of hard X-ray point sources in the Galactic Center (GC) region by NuSTAR. We have discovered 70 hard (3–79 keV) X-ray point sources in a 0.6 deg{}2 region around Sgr A* with a total exposure of 1.7 Ms, and 7 sources in the Sgr B2 field with 300 ks. We identify clear Chandra counterparts for 58 NuSTAR sources and assign candidate counterparts for the remaining 19. The NuSTAR survey reaches X-ray luminosities of ˜4× and ˜8 × 10{}32 erg s{}-1 at the GC (8 kpc) in the 3–10 and 10–40 keV bands, respectively. The source list includes three persistent luminous X-ray binaries (XBs) and the likely run-away pulsar called the Cannonball. New source-detection significance maps reveal a cluster of hard (>10 keV) X-ray sources near the Sgr A diffuse complex with no clear soft X-ray counterparts. The severe extinction observed in the Chandra spectra indicates that all the NuSTAR sources are in the central bulge or are of extragalactic origin. Spectral analysis of relatively bright NuSTAR sources suggests that magnetic cataclysmic variables constitute a large fraction (>40%–60%). Both spectral analysis and logN–logS distributions of the NuSTAR sources indicate that the X-ray spectra of the NuSTAR sources should have kT > 20 keV on average for a single temperature thermal plasma model or an average photon index of Γ = 1.5–2 for a power-law model. These findings suggest that the GC X-ray source population may contain a larger fraction of XBs with high plasma temperatures than the field population.

  15. The Baryon Cycle at High Redshifts: Effects of Galactic Winds on Galaxy Evolution in Overdense and Average Regions

    NASA Astrophysics Data System (ADS)

    Sadoun, Raphael; Shlosman, Isaac; Choi, Jun-Hwan; Romano-Díaz, Emilio

    2016-10-01

    We employ high-resolution cosmological zoom-in simulations focusing on a high-sigma peak and an average cosmological field at z ˜ 6-12 in order to investigate the influence of environment and baryonic feedback on galaxy evolution in the reionization epoch. Strong feedback, e.g., galactic winds, caused by elevated star formation rates (SFRs) is expected to play an important role in this evolution. We compare different outflow prescriptions: (i) constant wind velocity (CW), (ii) variable wind scaling with galaxy properties (VW), and (iii) no outflows (NW). The overdensity leads to accelerated evolution of dark matter and baryonic structures, absent from the “normal” region, and to shallow galaxy stellar mass functions at the low-mass end. Although CW shows little dependence on the environment, the more physically motivated VW model does exhibit this effect. In addition, VW can reproduce the observed specific SFR (sSFR) and the sSFR-stellar mass relation, which CW and NW fail to satisfy simultaneously. Winds also differ substantially in affecting the state of the intergalactic medium (IGM). The difference lies in the volume-filling factor of hot, high-metallicity gas, which is near unity for CW, while such gas remains confined in massive filaments for VW, and locked up in galaxies for NW. Such gas is nearly absent from the normal region. Although all wind models suffer from deficiencies, the VW model seems to be promising in correlating the outflow properties with those of host galaxies. Further constraints on the state of the IGM at high z are needed to separate different wind models.

  16. GALACTIC H{sub 2}CO DENSITOMETRY. I. PILOT SURVEY OF ULTRACOMPACT H II REGIONS AND METHODOLOGY

    SciTech Connect

    Ginsburg, Adam; Darling, Jeremy; Battersby, Cara; Zeiger, Ben; Bally, John

    2011-08-01

    We present a pilot survey of 21 lines of sight toward ultracompact H II (UCH II) regions and three toward continuum-free lines of sight in the formaldehyde (H{sub 2}CO) 1{sub 10}-1{sub 11} (6 cm) and 2{sub 11}-2{sub 12} (2 cm) transitions, using the H{sub 2}CO centimeter lines as a molecular gas densitometer. Using Arecibo and Green Bank beam-matched observations, we measure the density of 51 detected H{sub 2}CO line pairs and present upper limits on density for an additional 24 detected 1{sub 10}-1{sub 11} lines. We analyze the systematic uncertainties in the H{sub 2}CO densitometer, achieving H{sub 2} density measurements with accuracies {approx}0.1-0.3 dex. The densities measured are not correlated with distance, implying that it is possible to make accurate density measurements throughout the galaxy without a distance bias. We confirm that UCH II regions are associated with, and possibly embedded in, gas at densities n(H{sub 2}) {approx}> 10{sup 5} cm{sup -3}. The densities measured in line-of-sight molecular clouds suggest that they consist of low volume filling factor (f {approx} 10{sup -2}) gas at high (n(H{sub 2}) > 10{sup 4} cm{sup -3}) density, which is inconsistent with purely supersonic turbulence and requires high-density clumping greater than typically observed in gravoturbulent simulations. We observe complex line morphologies that indicate density variations with velocity around UCH II regions, and we classify a subset of the UCH II molecular envelopes as collapsing or expanding. We compare these measurements to Bolocam Galactic Plane Survey 1.1 mm observations, and note that most UCH II regions have 1.1 mm emission consisting of significant (5%-70%) free-free emission and are therefore not necessarily dominated by optically thin dust emission as is often assumed when computing clump masses. A comparison of our data with the Mangum et al. starburst sample shows that the area filling factor of dense (n(H{sub 2}) {approx} 10{sup 5} cm{sup -3

  17. Regional projections of nuclear and fossil electric power generation costs

    SciTech Connect

    Smolen, G.R.; Delene, J.G.; Fuller, L.C.; Bowers, H.I.

    1983-12-01

    The total busbar electric generating costs were estimated for locations in ten regions of the United States for base load nuclear and coal-fired power plants with a startup date of January 1995. A complete data set is supplied which specifies each parameter used to obtain the comparative results. When the comparison is based on reference cost parameters, nuclear- and coal-fired generation costs are found to be very close in most regions of the country. Nuclear power is favored in the South Atlantic region where coal must be transported over long distances, while coal-fired generation is favored in the Central and North Central regions where large reserves of cheaply mineable coal exist. The reference data set reflects recent electric utility construction experience. Significantly lower nuclear capital investment costs would result if regulatory reform and improved construction practices were instituted. The electric power generation costs for base load oil- and natural gas-fired plants were also estimated. These plants were found to be noncompetitive in all regions for those scenarios most likely to develop. Generation cost sensitivity to changes in various parameters was examined at a reference location. The sensitivity parameters included capital investment costs, lead times, capacity factors, costs of money, and coal and uranium prices. In addition to the levelized lifetime costs, year-by-year cash flows and revenue requirements are presented. The report concludes with an analysis of the economic merits of recycling spent fuel in light-water reactors.

  18. Kinematics and structure of clumps in broad-line regions in active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Ghayuri, Mohammad

    2016-10-01

    We use the Jeans equations for an ensemble of collisionless particles to describe the distribution of broad-line region (BLR) cloud in three classes: (A) non-disc (B) disc-wind (C) pure disc structure. We propose that clumpy structures in the brightest quasars belong to class A, fainter quasars and brighter Seyferts belong to class B, and dimmer Seyfert galaxies and all low-luminosity AGNs (LLAGNs) belong to class C. We derive the virial factor, f, for disc-like structures and find a negative correlation between the inclination angle, θ0, and f. We find similar behaviour for f as a function of the FWHM and σz, the z component of velocity dispersion. For different values of θ0 we find that 1.0 ≲ f ≲ 9.0 in type1 AGNs and 0.5 ≲ f ≲ 1.0 in type2 AGNs. Moreover we have 0.5 ≲ f ≲ 6.5 for different values of FWHM and 1.4 ≲ f ≲ 1.8 for different values of σz. We also find that f is relatively insensitive to the variations of bolometric luminosity and column density of each cloud and the range of variation of f is in order of 0.01. Considering wide range of f we see the use of average virial factor is not very safe. Therefore we propose AGN community to divide a sample into a few subsamples based on the value of θ0 and FWHM of members and calculate for each group separately to reduce uncertainty in black hole mass estimation.

  19. Consequences of Regional Scale Nuclear Conflicts and Acts of Individual Nuclear Terrorism

    NASA Astrophysics Data System (ADS)

    Toon, O. B.; Turco, R. P.; Robock, A.; Bardeen, C.; Oman, L.; Stenchikov, G. L.

    2006-12-01

    The number of nuclear warheads in the world has fallen by about a factor of three since its peak in 1986. However, the potential exists for numerous regional nuclear arms races, and for a significant expansion in the number of nuclear weapons states. Eight countries are known to have nuclear weapons, 2 are constructing them, and an additional 32 nations already have the fissile material needed to build weapons if they so desire. Population and economic activity worldwide are congregated to an increasing extent in "megacities", which are ideal targets for nuclear weapons. We find that low yield weapons, which new nuclear powers are likely to construct, can produce 100 times as many fatalities and 100 times as much smoke from fires per kt yield as high-yield weapons, if they are targeted at city centers. A single low-yield nuclear detonation in an urban center could lead to more fatalities, in some cases by orders of magnitude, than have occurred in major historical conflicts. A regional war between the smallest current nuclear states involving 100 15-kt explosions (less than 0.1% of the explosive yield of the current global nuclear arsenal) could produce direct fatalities comparable to all of those worldwide in World War II (WW-II), or to those once estimated for a "counterforce" nuclear war between the superpowers. Portions of megacities attacked with nuclear devices or exposed to fallout of long-lived isotopes, through armed conflict or terrorism, would likely be abandoned indefinitely, with severe national and international implications. Smoke from urban firestorms in a regional war might induce significant climatic and ozone anomalies on global scales. While there are many uncertainties in the issues we discuss here, the major uncertainties are the type and scale of conflict that might occur. Each of these potential hazards deserves careful analysis by governments worldwide advised by a broad section of the world scientific community, as well as widespread

  20. Nuclear Hybrid Energy Systems Regional Studies: West Texas & Northeastern Arizona

    SciTech Connect

    Garcia, Humberto E.; Chen, Jun; Kim, Jong Suk; McKellar, Michael George; Deason, Wesley R; Richard B. Vilim; Bragg-Sitton, Shannon M.; Boardman, Richard D.

    2015-04-01

    The primary objective of this study is to conduct a preliminary dynamic analysis of two realistic hybrid energy systems (HES) including a nuclear reactor as the main baseload heat generator (denoted as nuclear HES or nuclear hybrid energy systems [[NHES]) and to assess the local (e.g., HES owners) and system (e.g., the electric grid) benefits attainable by the application of NHES in scenarios with multiple commodity production and high penetration of renewable energy. It is performed for regional cases not generic examples based on available resources, existing infrastructure, and markets within the selected regions. This study also briefly addresses the computational capabilities developed to conduct such analyses, reviews technical gaps, and suggests some research paths forward.

  1. Exploring the crowded central region of ten Galactic globular clusters using EMCCDs. Variable star searches and new discoveries

    NASA Astrophysics Data System (ADS)

    Figuera Jaimes, R.; Bramich, D. M.; Skottfelt, J.; Kains, N.; Jørgensen, U. G.; Horne, K.; Dominik, M.; Alsubai, K. A.; Bozza, V.; Calchi Novati, S.; Ciceri, S.; D'Ago, G.; Galianni, P.; Gu, S.-H.; Harpsøe, K. B. W.; Haugbølle, T.; Hinse, T. C.; Hundertmark, M.; Juncher, D.; Korhonen, H.; Mancini, L.; Popovas, A.; Rabus, M.; Rahvar, S.; Scarpetta, G.; Schmidt, R. W.; Snodgrass, C.; Southworth, J.; Starkey, D.; Street, R. A.; Surdej, J.; Wang, X.-B.; Wertz, O.

    2016-04-01

    Aims: We aim to obtain time-series photometry of the very crowded central regions of Galactic globular clusters; to obtain better angular resolution thanhas been previously achieved with conventional CCDs on ground-based telescopes; and to complete, or improve, the census of the variable star population in those stellar systems. Methods: Images were taken using the Danish 1.54-m Telescope at the ESO observatory at La Silla in Chile. The telescope was equipped with an electron-multiplying CCD, and the short-exposure-time images obtained (ten images per second) were stacked using the shift-and-add technique to produce the normal-exposure-time images (minutes). Photometry was performed via difference image analysis. Automatic detection of variable stars in the field was attempted. Results: The light curves of 12 541 stars in the cores of ten globular clusters were statistically analysed to automatically extract the variable stars. We obtained light curves for 31 previously known variable stars (3 long-period irregular, 2 semi-regular, 20 RR Lyrae, 1 SX Phoenicis, 3 cataclysmic variables, 1 W Ursae Majoris-type and 1 unclassified) and we discovered 30 new variables (16 long-period irregular, 7 semi-regular, 4 RR Lyrae, 1 SX Phoenicis and 2 unclassified). Fluxes and photometric measurements for these stars are available in electronic form through the Strasbourg astronomical Data Center. Based on data collected by the MiNDSTEp team with the Danish 1.54m telescope at ESO's La Silla observatory in Chile.Full Table 1 is only available at CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/588/A128

  2. CONNECTION BETWEEN MID-INFRARED EMISSION PROPERTIES AND NARROW-LINE REGION OUTFLOWS IN TYPE 1 ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Zhang Kai; Wang Tinggui; Dong Xiaobo; Yan Lin

    2013-05-01

    The location of warm dust producing the mid-infrared (MIR) emission in type 1 active galactic nuclei (AGNs) is complex and not yet fully known. We explore this problem by studying how the MIR covering factor (CF{sub MIR} = L{sub MIR}/L{sub bol}) correlates with the fundamental parameters of AGN accretion process (such as L{sub bol}, black hole mass M{sub BH}, and Eddington ratio L/L{sub Edd}) and the properties of narrow emission lines (as represented by [O III] {lambda}5007), using large data sets derived from the Sloan Digital Sky Spectroscopic Survey (SDSS) and the Wide Infrared Sky Survey (WISE). First, we find that the luminosity of the [O III] wing component (L{sub wing}) correlates more tightly with the continuum luminosity ({lambda}L{sub {lambda}}(5100)) than the luminosity of the line core component (L{sub core}) does, which is in line with our previous conclusion that the wing component, generally blueshifted, originates from the polar outflows in the inner narrow-line region (NLR). We then find that the MIR CF shows the strongest correlation with L{sub wing}/L{sub bol} rather than with L{sub core}/L{sub bol} or the above fundamental AGN parameters, and the correlation becomes stronger as the infrared wavelength increases. We also confirm the anti-correlations of CF{sub MIR} with L{sub bol} and M{sub BH}, and the lack of dependence of CF{sub MIR} on the Eddington ratio. These results suggest that a large fraction of the warm dust producing MIR emission in AGNs is likely embedded in polar outflows in the NLR instead of in the torus.

  3. The Power Source(s) of Nearby Low-Ionization Nuclear Emission Regions

    NASA Astrophysics Data System (ADS)

    Molina, Mallory; Eracleous, Michael; Maoz, Dan; Barth, Aaron J.; Walsh, Jonelle; Ho, Luis C.; Shields, Joseph C.

    2015-01-01

    The majority of low-ionization nuclear emission regions (LINERs) harbor supermassive black holes (SMBHs) with very low accretion rates. Since SMBHs spend most of their lifetimes in these low-accretion rate states, understanding LINERs is important for understanding active galactic nuclei (AGN) in the context of galaxy evolution. On scales of ~100 pc, the energy budget of LINERs appears to be deficient when the only source of power considered is the AGN. Thus, other energy sources are likely to contribute to the excitation of the emission-line gas. To probe these sources, we observed three nearby, bright LINERs, NGC 1052, NGC 4278 and NGC 4579, with the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope (HST). We specifically looked at the 0.1-1 arcsecond (corresponding to 5-50 pc) scale to find what and how far from the nucleus these other energy sources are. After subtracting both the unresolved nuclear light and the spatially-extended starlight, we measured a number of diagnostic emission line ratios. We find that line ratios, such as [O III]/[O II] and [O III]/H-beta change as a function of distance from the nucleus. Within 5 pc, the line ratios suggest AGN photoionization. At larger distances the line ratios seem to be inconsistent with AGN photoionization, but they appear to be consistent with excitation by hot stars or shocks.

  4. Near-infrared images of the nuclear region of NGC 5128

    NASA Technical Reports Server (NTRS)

    Turner, Paula C.; Forrest, William J.; Pipher, Judith L.; Shure, Mark A.

    1992-01-01

    High-resolution near-infrared images of NGC 5128 (Centaurus A) are presented, which probe the optically obscured nuclear region. The images show a central source at K (2.23 microns) and 3.26 microns. This central object is not prominent in the shorter wavelength images at J and H (1.23 and 1.65 micron, respectively), probably due to high extinction. The color images (H - K and J - H) provide evidence for a steep gradient in extinction across the array field. The images indicate three components: a red, variable, compact nucleus; the diffuse elliptical galaxy starlight; and a blue extension to the NE. The nucleus has decreased in flux density by a factor of 2.5 over less than about 5 yr at 3.26 microns. However, current spectral constraints on the nuclear source at near-infrared wavelengths cannot definitively determine the relative contributions from the known ratio synchrotron source (AGN) and from various possible dust-enshrouded thermal sources. The blue spot, approximately 7.6 +/- 0.1 arcsec NE of the nucleus appears to be a hole in the extinction, possibly enhanced by scattered light from the active galactic nucleus.

  5. MASSIVE CLUSTERS IN THE INNER REGIONS OF NGC 1365: CLUSTER FORMATION AND GAS DYNAMICS IN GALACTIC BARS

    SciTech Connect

    Elmegreen, Bruce G.; Galliano, Emmanuel; Alloin, Danielle E-mail: egallian@on.b

    2009-10-01

    Cluster formation and gas dynamics in the central regions of barred galaxies are not well understood. This paper reviews the environment of three 10{sup 7} M {sub sun} clusters near the inner Lindblad resonance (ILR) of the barred spiral NGC 1365. The morphology, mass, and flow of H I and CO gas in the spiral and barred regions are examined for evidence of the location and mechanism of cluster formation. The accretion rate is compared with the star formation rate to infer the lifetime of the starburst. The gas appears to move from inside corotation in the spiral region to looping filaments in the interbar region at a rate of approx6 M {sub sun} yr{sup -1} before impacting the bar dustlane somewhere along its length. The gas in this dustlane moves inward, growing in flux as a result of the accretion to approx40 M {sub sun} yr{sup -1} near the ILR. This inner rate exceeds the current nuclear star formation rate by a factor of 4, suggesting continued buildup of nuclear mass for another approx0.5 Gyr. The bar may be only 1-2 Gyr old. Extrapolating the bar flow back in time, we infer that the clusters formed in the bar dustlane outside the central dust ring at a position where an interbar filament currently impacts the lane. The ram pressure from this impact is comparable to the pressure in the bar dustlane, and both are comparable to the pressure in the massive clusters. Impact triggering is suggested. The isothermal assumption in numerical simulations seems inappropriate for the rarefaction parts of spiral and bar gas flows. The clusters have enough lower-mass counterparts to suggest they are part of a normal power-law mass distribution. Gas trapping in the most massive clusters could explain their [Ne II] emission, which is not evident from the lower-mass clusters nearby.

  6. A Kiloparsec-scale Nuclear Stellar Disk in the Milky Way as a Possible Explanation of the High Velocity Peaks in the Galactic Bulge

    NASA Astrophysics Data System (ADS)

    Debattista, Victor P.; Ness, Melissa; Earp, Samuel W. F.; Cole, David R.

    2015-10-01

    The Apache Point Observatory Galactic Evolution Experiment has measured the stellar velocities of red giant stars in the inner Milky Way. We confirm that the line of sight velocity distributions (LOSVDs) in the mid-plane exhibit a second peak at high velocities, whereas those at | b| =2^\\circ do not. We use a high resolution simulation of a barred galaxy, which crucially includes gas and star formation, to guide our interpretation of the LOSVDs. We show that the data are fully consistent with the presence of a thin, rapidly rotating, nuclear disk extending to ∼1 kpc. This nuclear disk is orientated perpendicular to the bar and is likely to be composed of stars on x2 orbits. The gas in the simulation is able to fall onto such orbits, leading to stars populating an orthogonal disk.

  7. THE GALACTIC CENTER: NOT AN ACTIVE GALACTIC NUCLEUS

    SciTech Connect

    An, Deokkeun; Ramirez, Solange V.; Sellgren, Kris

    2013-06-01

    We present 10 {mu}m-35 {mu}m Spitzer spectra of the interstellar medium in the Central Molecular Zone (CMZ), the central 210 pc Multiplication-Sign 60 pc of the Galactic center (GC). We present maps of the CMZ in ionic and H{sub 2} emission, covering a more extensive area than earlier spectroscopic surveys in this region. The radial velocities and intensities of ionic lines and H{sub 2} suggest that most of the H{sub 2} 0-0 S(0) emission comes from gas along the line-of-sight, as found by previous work. We compare diagnostic line ratios measured in the Spitzer Infrared Nearby Galaxies Survey to our data. Previous work shows that forbidden line ratios can distinguish star-forming galaxies from low-ionization nuclear emission-line regions (LINERs) and active galactic nuclei (AGNs). Our GC line ratios agree with star-forming galaxies and not with LINERs or AGNs.

  8. Climatic Consequences and Agricultural Impact of Regional Nuclear Conflict

    NASA Astrophysics Data System (ADS)

    Robock, Alan; Mills, Michael; Toon, Owen Brian; Xia, Lili

    2013-04-01

    A nuclear war between India and Pakistan, with each country using 50 Hiroshima-sized atom bombs as airbursts on urban areas, would inject smoke from the resulting fires into the stratosphere. This could produce climate change unprecedented in recorded human history and global-scale ozone depletion, with enhanced ultraviolet (UV) radiation reaching the surface. Simulations with the NCAR Whole Atmosphere Community Climate Model (WACCM), run at higher vertical and horizontal resolution than a previous simulation with the NASA Goddard Institute for Space Studies ModelE, and incorporating ozone chemistry for the first time, show a longer stratospheric residence time for smoke and hence a longer-lasting climate response, with global average surface air temperatures still 1.1 K below normal and global average precipitation 4% below normal after a decade. The erythemal dose from the enhanced UV radiation would greatly increase, in spite of enhanced absorption by the remaining smoke, with the UV index more than 3 units higher in the summer midlatitudes, even after a decade. Scenarios of changes in temperature, precipitation, and downward shortwave radiation from the ModelE and WACCM simulations, applied to the Decision Support System for Agrotechnology Transfer crop model for winter wheat, rice, soybeans, and maize by perturbing observed time series with anomalies from the regional nuclear war simulations, produce decreases of 10-50% in yield averaged over a decade, with larger decreases in the first several years, over several regions in the midlatitudes of the Northern Hemisphere. The impact of the nuclear war simulated here, using much less than 1% of the global nuclear arsenal, would be devastating to world agricultural production and trade, possibly sentencing a billion people now living marginal existences to starvation. The continued environmental threat of the use of even a small number of nuclear weapons must be considered in nuclear policy deliberations in Russia

  9. Atmospheric effects and societal consequences of regional scale nuclear conflicts and acts of individual nuclear terrorism

    NASA Astrophysics Data System (ADS)

    Toon, O. B.; Turco, R. P.; Robock, A.; Bardeen, C.; Oman, L.; Stenchikov, G. L.

    2007-04-01

    We assess the potential damage and smoke production associated with the detonation of small nuclear weapons in modern megacities. While the number of nuclear warheads in the world has fallen by about a factor of three since its peak in 1986, the number of nuclear weapons states is increasing and the potential exists for numerous regional nuclear arms races. Eight countries are known to have nuclear weapons, 2 are constructing them, and an additional 32 nations already have the fissile material needed to build substantial arsenals of low-yield (Hiroshima-sized) explosives. Population and economic activity worldwide are congregated to an increasing extent in megacities, which might be targeted in a nuclear conflict. We find that low yield weapons, which new nuclear powers are likely to construct, can produce 100 times as many fatalities and 100 times as much smoke from fires per kt yield as previously estimated in analyses for full scale nuclear wars using high-yield weapons, if the small weapons are targeted at city centers. A single "small" nuclear detonation in an urban center could lead to more fatalities, in some cases by orders of magnitude, than have occurred in the major historical conflicts of many countries. We analyze the likely outcome of a regional nuclear exchange involving 100 15-kt explosions (less than 0.1% of the explosive yield of the current global nuclear arsenal). We find that such an exchange could produce direct fatalities comparable to all of those worldwide in World War II, or to those once estimated for a "counterforce" nuclear war between the superpowers. Megacities exposed to atmospheric fallout of long-lived radionuclides would likely be abandoned indefinitely, with severe national and international implications. Our analysis shows that smoke from urban firestorms in a regional war would rise into the upper troposphere due to pyro-convection. Robock et al. (2007) show that the smoke would subsequently rise deep into the stratosphere due

  10. Decadal reduction of Chinese agriculture after a regional nuclear war

    NASA Astrophysics Data System (ADS)

    Xia, Lili; Robock, Alan; Mills, Michael; Stenke, Andrea; Helfand, Ira

    2015-02-01

    A regional nuclear war between India and Pakistan could decrease global surface temperature by 1°C-2°C for 5-10 years and have major impacts on precipitation and solar radiation reaching Earth's surface. Using a crop simulation model forced by three global climate model simulations, we investigate the impacts on agricultural production in China, the largest grain producer in the world. In the first year after the regional nuclear war, a cooler, drier, and darker environment would reduce annual rice production by 30 megaton (Mt) (29%), maize production by 36 Mt (20%), and wheat production by 23 Mt (53%). With different agriculture management—no irrigation, auto irrigation, 200 kg/ha nitrogen fertilizer, and 10 days delayed planting date—simulated national crop production reduces 16%-26% for rice, 9%-20% for maize, and 32%-43% for wheat during 5 years after the nuclear war event. This reduction of food availability would continue, with gradually decreasing amplitude, for more than a decade. Assuming these impacts are indicative of those in other major grain producers, a nuclear war using much less than 1% of the current global arsenal could produce a global food crisis and put a billion people at risk of famine.

  11. EVIDENCE FOR THE INTERMEDIATE BROAD-LINE REGION OF REVERBERATION-MAPPED ACTIVE GALACTIC NUCLEUS PG 0052+251

    SciTech Connect

    Zhang Xueguang

    2011-11-10

    We study the properties of the broad-line region (BLR) of a well-known reverberation-mapped active galactic nucleus (AGN) in order to find reliable evidence for the intermediate BLR. We first check properties of the mapped AGN collected from the literature in the plane of {sigma}{sup 2}{sub H}{beta}/{sigma}H{alpha} {sup 2} versus R {sup H}{alpha}{sub BLR}/R{sub BLR} {sup H}{beta}. Commonly, virial black hole masses based on observed broad H{alpha} and H{beta} should be coincidental. However, among the mapped objects, PG 0052 and NGC 4253 are two apparent outliers in the plane of {sigma}{sup 2}{sub H}{beta}/{sigma}H{alpha} {sup 2} versus R {sup H}{alpha}{sub BLR}/R{sub BLR} {sup H}{beta}, which indicates that BLRs of PG 0052 and NGC 4253 have some special characters. Based on the 55 public spectra of PG 0052, the BLR of PG 0052 has been carefully studied in detail. We find that the line width ratio of the total observed broad H{alpha} to the total observed broad H{beta} is {approx}0.7, which is much smaller than the theoretical/observational value of {approx}0.9. Furthermore, the flux ratio of the total broad H{alpha} to the total broad H{beta} is about 6.8 (Balmer decrement), which is not a reasonable value for the blue quasar PG 0052+251. Moreover, properties of line cores based on the principal component analysis technique confirm that there is one inner broad component and one seriously obscured intermediate broad component in the BLR of PG 0052. If the seriously obscured intermediate BLR was accepted, properties of PG 0052 in the plane of {sigma}{sup 2}{sub H}{beta}/{sigma}H{alpha} {sup 2} versus R {sup H}{alpha}{sub BLR}/R{sub BLR} {sup H}{beta} could be reproduced, which indicates that the intermediate BLR actually is appropriate for the mapped quasar PG 0052+251. Finally, the large distance between the inner and the intermediate components of the BLR based on the results of the cross-correlation function rejects the possibility that the intermediate

  12. Development of regional network for nuclear information in Latin America

    NASA Astrophysics Data System (ADS)

    Ebinuma, Yukio

    Among the recent INIS activities several interesting items are reported. In particular Latin America area where active movements have been seen recently is described in detail in terms of INIS information services. The author reports Latin America regional nuclear information project which has been implemented as 5-year project since 1985 supported by IAEA, and its progress, and describes information service system in Brazil which plays the core role in promoting this project.

  13. Climatic Consequences and Agricultural Impact of Regional Nuclear Conflict

    NASA Astrophysics Data System (ADS)

    Toon, O. B.; Robock, A.; Mills, M. J.; Xia, L.

    2013-05-01

    A nuclear war between India and Pakistan, with each country using 50 Hiroshima-sized atom bombs as airbursts on urban areas, would inject smoke from the resulting fires into the stratosphere.This could produce climate change unprecedented in recorded human history and global-scale ozone depletion, with enhanced ultraviolet (UV) radiation reaching the surface.Simulations with the Whole Atmosphere Community Climate Model (WACCM), run at higher vertical and horizontal resolution than a previous simulation with the NASA Goddard Institute for Space Studies ModelE, and incorporating ozone chemistry for the first time, show a longer stratospheric residence time for smoke and hence a longer-lasting climate response, with global average surface air temperatures still 1.1 K below normal and global average precipitation 4% below normal after a decade.The erythemal dose from the enhanced UV radiation would greatly increase, in spite of enhanced absorption by the remaining smoke, with the UV index more than 3 units higher in the summer midlatitudes, even after a decade. Scenarios of changes in temperature, precipitation, and downward shortwave radiation from the ModelE and WACCM simulations, applied to the Decision Support System for Agrotechnology Transfer crop model for winter wheat, rice, soybeans, and maize by perturbing observed time series with anomalies from the regional nuclear war simulations, produce decreases of 10-50% in yield averaged over a decade, with larger decreases in the first several years, over the midlatitudes of the Northern Hemisphere. The impact of the nuclear war simulated here, using much less than 1% of the global nuclear arsenal, would be devastating to world agricultural production and trade, possibly sentencing a billion people now living marginal existences to starvation.The continued environmental threat of the use of even a small number of nuclear weapons must be considered in nuclear policy deliberations in Russia, the U.S., and the rest of

  14. Atmospheric effects and societal consequences of regional scale nuclear conflicts and acts of individual nuclear terrorism

    NASA Astrophysics Data System (ADS)

    Toon, O. B.; Turco, R. P.; Robock, A.; Bardeen, C.; Oman, L.; Stenchikov, G. L.

    2006-11-01

    We assess the potential damage and smoke production associated with the detonation of small nuclear weapons in modern megacities. While the number of nuclear warheads in the world has fallen by about a factor of three since its peak in 1986, the number of nuclear weapons states is increasing and the potential exists for numerous regional nuclear arms races. Eight countries are known to have nuclear weapons, 2 are constructing them, and an additional 32 nations already have the fissile material needed to build substantial arsenals of low-yield (Hiroshima-sized) explosives. Population and economic activity worldwide are congregated to an increasing extent in megacities, which might be targeted in a nuclear conflict. Our analysis shows that, per kiloton of yield, low yield weapons can produce 100 times as many fatalities and 100 times as much smoke from fires as high-yield weapons, if they are targeted at city centers. A single "small'' nuclear detonation in an urban center could lead to more fatalities, in some cases by orders of magnitude, than have occurred in the major historical conflicts of many countries. We analyze the likely outcome of a regional nuclear exchange involving 100 15-kt explosions (less than 0.1% of the explosive yield of the current global nuclear arsenal). We find that such an exchange could produce direct fatalities comparable to all of those worldwide in World War II, or to those once estimated for a "counterforce'' nuclear war between the superpowers. Megacities exposed to atmospheric fallout of long-lived radionuclides would likely be abandoned indefinitely, with severe national and international implications. Our analysis shows that smoke from urban firestorms in a regional war would rise into the upper troposphere due to pyro-convection. Robock et al. (2006) show that the smoke would subsequently rise deep into the stratosphere due to atmospheric heating, and then might induce significant climatic anomalies on global scales.We also

  15. New Wolf-Rayet stars in Galactic open clusters - Sher 1 and the giant H II region core Westerlund 2

    NASA Technical Reports Server (NTRS)

    Moffat, Anthony F. J.; Shara, Michael M.; Potter, Michael

    1991-01-01

    Two new Galactic Wolf-Rayet stars were found in open clusters: a WN4 star in the O9 cluster Sher 1 and a WN7 star in the O7 cluster Westerlund 2. This confirms a previous trend, namely that fainter, hotter WN stars tend to be older than brighter, cooler WN stars. This may be a consequence of evolution via extreme mass loss.

  16. DUST IN THE POLAR REGION AS A MAJOR CONTRIBUTOR TO THE INFRARED EMISSION OF ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Hoenig, S. F.; Antonucci, R.; Kishimoto, M.; Tristram, K. R. W.; Asmus, D.; Weigelt, G.; Prieto, M. A.; Gandhi, P.; Burtscher, L.; Duschl, W. J.

    2013-07-10

    Dust around active galactic nuclei (AGNs) is distributed over a wide range of spatial scales and can be observed in the infrared (IR). It is generally assumed that the distribution on parsec scales forms a geometrically and optically thick entity in the equatorial plane around the accretion disk and broad-line region-dubbed {sup d}ust torus{sup -}that emits the bulk of the subarcsecond-scale IR emission and gives rise to orientation-dependent obscuration. However, recent IR interferometry studies with unprecedented position angle (P.A.) and baseline coverage on these small scales in two obscured (type 2) AGNs have revealed that the majority of the mid-IR emission in these objects is elongated in the polar direction. These observations are difficult to reconcile with the standard interpretation that most of the parsec-scale mid-IR emission in AGNs originate from the torus and challenges the justification of using simple torus models to model the broadband IR emission. Here, we report detailed interferometry observations of the unobscured (type 1) AGN in NGC 3783 that allow us to constrain the size, elongation, and direction of the mid-IR emission with high accuracy. The mid-IR emission is characterized by a strong elongation toward position angle P.A. -52 Degree-Sign , closely aligned with the polar axis (P.A. -45 Degree-Sign ). We determine half-light radii along the major and minor axes at 12.5 {mu}m of (20.0 {+-} 3.0) mas Multiplication-Sign (6.7 {+-} 1.0) mas or (4.23 {+-} 0.63) pc Multiplication-Sign (1.42 {+-} 0.21) pc, which corresponds to intrinsically scaled sizes of (69.4 {+-} 10.8) r{sub in} Multiplication-Sign (23.3 {+-} 3.5) r{sub in} for the inner dust radius of r{sub in} = 0.061 pc as inferred from near-IR reverberation mapping. This implies an axis ratio of 3:1, with about 60%-90% of the 8-13 {mu}m emission associated with the polar-elongated component. It is quite likely that the hot-dust emission as recently resolved by near-IR interferometry is

  17. The Nuclear Jet and Counterjet Region of the Radio Galaxy Cygnus A

    NASA Astrophysics Data System (ADS)

    Bartel, N.; Sorathia, B.; Bietenholz, M. F.; Carilli, C. L.; Diamond, P.

    1995-12-01

    Very-long-baseline interferometry images of the nuclear region of the radio galaxy Cygnus A reveal a pronounced "core" and a knotty jet and counterjet. The knots are moving away from the core at apparent speeds which are subluminal for h = 1 [h = H_0/100 km.s-1.Mpc-1;1 parsec (pc) = 3.09 x 1016m] and about c for h = 0.5. The jet is aligned with the outer, kiloparsec-scale jet to within 2^circ. The counterjet has a total flux density at 5 GHz of about one-fifth of that of the jet. In the context of the twin relativistic jet model for active galactic nuclei, the jet in Cygnus A is oriented at an angle to our line of sight of 35-80^circ and 55-85^circ, and the intrinsic velocity of the jet fluid is 0.4-0.6c and 0.6-1c for h = 1 and h = 0.5, respectively.

  18. The nuclear jet and counterjet region of the radio galaxy Cygnus A.

    PubMed Central

    Bartel, N; Sorathia, B; Bietenholz, M F; Carilli, C L; Diamond, P

    1995-01-01

    Very-long-baseline interferometry images of the nuclear region of the radio galaxy Cygnus A reveal a pronounced "core" and a knotty jet and counterjet. The knots are moving away from the core at apparent speeds which are subluminal for h = 1 [h = H0/100 km.s-1.Mpc-1;1 parsec (pc) = 3.09 x 10(16)m] and about c for h = 0.5. The jet is aligned with the outer, kiloparsec-scale jet to within 2 degrees. The counterjet has a total flux density at 5 GHz of about one-fifth of that of the jet. In the context of the twin relativistic jet model for active galactic nuclei, the jet in Cygnus A is oriented at an angle to our line of sight of 35-80 degrees and 55-85 degrees, and the intrinsic velocity of the jet fluid is 0.4-0.6c and 0.6-1c for h = 1 and h = 0.5, respectively. PMID:11607600

  19. ON THE O/H, Mg/H, Si/H, AND Fe/H GAS AND DUST ABUNDANCE RATIOS IN GALACTIC AND EXTRAGALACTIC H II REGIONS

    SciTech Connect

    Peimbert, Antonio; Peimbert, Manuel E-mail: peimbert@astroscu.unam.m

    2010-11-20

    We derive the Mg/H ratio in the Orion nebula and in 30 Doradus. We also derive the O/H and the Fe/O ratios in the extremely metal-poor galaxy SBS 0335-052 E. We estimate the dust depletions of Mg, Si, and Fe in Galactic and extragalactic H II regions. From these depletions we estimate the fraction of O atoms embedded in dust as a function of the O/H ratio. We find an increasing depletion of O with increasing O/H. The O depletion increases from about 0.08 dex, for the metal poorest H II regions known, to about 0.12 dex, for metal-rich H II regions. This depletion has to be considered to compare nebular with stellar abundances.

  20. Logarithmic Spiral Arm Pitch Angle of Spiral Galaxies: Measurement and Relationship to Galactic Structure and Nuclear Supermassive Black Hole Mass

    NASA Astrophysics Data System (ADS)

    Davis, Benjamin

    In this dissertation, I explore the geometric structure of spiral galaxies and how the visible structure can provide information about the central mass of a galaxy, the density of its galactic disk, and the hidden mass of the supermassive black hole in its nucleus. In order to quantitatively measure the logarithmic spiral pitch angle (a measurement of tightness of the winding) of galactic spiral arms, I led an effort in our research group (the Arkansas Galaxy Evolution Survey) to modify existing two-dimensional fast Fourier transform software to increase its efficacy and accuracy. Using this software, I was able to lead an effort to calculate a black hole mass function (BHMF) for spiral galaxies in our local Universe. This work effectively provides us with a census of local black holes and establishes an endpoint on the evolutionary history of the BHMF for spiral galaxies. Furthermore, my work has indicated a novel fundamental relationship between the pitch angle of a galaxy's spiral arms, the maximum density of neutral atomic hydrogen in its disk, and the stellar mass of its bulge. This result provides strong support for the density wave theory of spiral structure in disk galaxies and poses a critical question of the validity of rival theories for the genesis of spiral structure in disk galaxies.

  1. O VI Emission in Nuclear Region of NGC 1068

    SciTech Connect

    Zheng, W.; Sahnow, D.; Tsvetanov, Z.; Kriss, G. A.; Wang, J.-X.; Allen, M.; Dopita, M.; Bicknell, G.

    2009-05-24

    FUSE Spectra of the nuclear region of NGC 1068 find strong OVI emission consisting of a pair of narrow and broad components. There is a gradient in the velocity field for the narrow O VI component of {approx}200 kms{sup -1} from {approx}2'' southwest of the nucleus to {approx}4'' northeast. A similar pattern is also observed with the broad O VI component, with a gradient of {approx}3000 kms{sup -1}. These results are consistent with the HST/STIS findings and suggest a biconical structure in which the velocity field is mainly radial outflow.

  2. Nuclear structure investigations in the region of superheavy nuclei

    SciTech Connect

    Hessberger, F. P.

    2007-08-15

    Radioactive decay from the ground state or isomeric states has been investigated for a series of nuclei in the region of Z = 100-106 by means of {alpha}-{gamma}-or evaporation residue-({gamma}, conversion electron)-measurements in prompt and delayed coincidence. Systematic trends in single-particle level energies in N = 145-151 odd-even isotones could be extended up to Z = 104, while an energy systematics of lowlying Nilsson levels in odd-mass einsteinium isotopes was established. Information on nuclear levels at E* > 500 keV was obtained from the decay study of isomeric states in {sup 251-255}No.

  3. Galactic arm structure and gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Bignami, G. F.; Fichtel, C. E.

    1974-01-01

    Unexpectedly high energy gamma radiation over a broad region of the galactic plane in the general direction of the galactic center was observed. A model is proposed wherein the galactic cosmic rays are preferentially located in the high matter density regions of galactic arm segments, as a result of the weight of the matter in these arms tieing the magnetic fields and hence the cosmic rays to these regions. The presently observed galactic gamma ray longitudinal distribution can be explained with the current estimate of the average galactic matter density: if the average arm to interarm matter ratio is five to one for the major arm segments toward the galactic center from the sun; and if the cosmic ray density normalized to its local value is assumed to be directly proportional to the matter density.

  4. Massive global ozone loss predicted following regional nuclear conflict.

    PubMed

    Mills, Michael J; Toon, Owen B; Turco, Richard P; Kinnison, Douglas E; Garcia, Rolando R

    2008-04-01

    We use a chemistry-climate model and new estimates of smoke produced by fires in contemporary cities to calculate the impact on stratospheric ozone of a regional nuclear war between developing nuclear states involving 100 Hiroshima-size bombs exploded in cities in the northern subtropics. We find column ozone losses in excess of 20% globally, 25-45% at midlatitudes, and 50-70% at northern high latitudes persisting for 5 years, with substantial losses continuing for 5 additional years. Column ozone amounts remain near or <220 Dobson units at all latitudes even after three years, constituting an extratropical "ozone hole." The resulting increases in UV radiation could impact the biota significantly, including serious consequences for human health. The primary cause for the dramatic and persistent ozone depletion is heating of the stratosphere by smoke, which strongly absorbs solar radiation. The smoke-laden air rises to the upper stratosphere, where removal mechanisms are slow, so that much of the stratosphere is ultimately heated by the localized smoke injections. Higher stratospheric temperatures accelerate catalytic reaction cycles, particularly those of odd-nitrogen, which destroy ozone. In addition, the strong convection created by rising smoke plumes alters the stratospheric circulation, redistributing ozone and the sources of ozone-depleting gases, including N(2)O and chlorofluorocarbons. The ozone losses predicted here are significantly greater than previous "nuclear winter/UV spring" calculations, which did not adequately represent stratospheric plume rise. Our results point to previously unrecognized mechanisms for stratospheric ozone depletion. PMID:18391218

  5. Neutron star population in the Galactic center region as a potential source of polarized X-ray emission

    NASA Astrophysics Data System (ADS)

    Zajacek, Michal; Karas, Vladimir; Eckart, Andreas

    2016-06-01

    We analyse the emission properties of neutron stars that are predicted to exist in large numbers of the order of 10000 in the innermost parts of the Galactic center. A part of the population of isolated neutron stars propagates supersonically through denser ionized streams of the Minispiral (Sgr A West), forming bow shocks where particles are accelerated and are expected to produce polarized X-ray synchrotron signal. Another source of the synchrotron emission is an elongated magnetosphere and tail. We investigate whether the polarized X-ray emission from Galactic center neutron stars will be potentially detectable in the framework of future X-ray polarimeters. A special case is a detected young neutron star - magnetar SGRJ1745-2900 - that has undergone a series of outbursts with a peak X-ray luminosity of the order of 10^{35} erg s^{-1} (1-10 keV). Apart from an intrinsic X-ray emission, the X-ray emission from neutron star outbursts may be scattered by molecular clouds in the Central Molecular Zone by Thomson scattering, which is another potential source of polarized X-ray emission.

  6. An Analysis of Nuclear Related Technician Manpower in Western States for the Region Served by the Western Interstate Nuclear Board.

    ERIC Educational Resources Information Center

    Blair, Larry M.; Barker, Larry

    The study presents the results of a survey of current (1975) and projected near-future (1975 through 1977) labor market trends for nuclear-related technicians in the 12-State Western Interstate Nuclear Region Board (WINB) area. The survey covered employers and educators/trainers of nuclear related manpower in private industry, research…

  7. Galactic Winds

    NASA Astrophysics Data System (ADS)

    Veilleux, Sylvain

    Galactic winds have become arguably one of the hottest topics in extragalactic astronomy. This enthusiasm for galactic winds is due in part to the detection of winds in many, if not most, high-redshift galaxies. Galactic winds have also been invoked by theorists to (1) suppress the number of visible dwarf galaxies and avoid the "cooling catastrophe" at high redshift that results in the overproduction of massive luminous galaxies, (2) remove material with low specific angular momentum early on and help enlarge gas disks in CDM + baryons simulations, (3) reduce the dark mass concentrations in galaxies, (4) explain the mass-metallicity relation of galaxies from selective loss of metal-enriched gas from smaller galaxies, (5) enrich and "preheat" the ICM, (6) enrich the IGM without disturbing the Lyαforest significantly, and (7) inhibit cooling flows in galaxy clusters with active cD galaxies. The present paper highlights a few key aspects of galactic winds taken from a recent ARAA review by Veilleux, Cecil, &Bland-Hawthorn (2005; herafter VCBH). Readers interested in a more detailed discussion of this topic are encouraged to refer to the original ARAA article.

  8. Cloud Structure of Galactic OB Cluster-forming Regions from Combining Ground- and Space-based Bolometric Observations

    NASA Astrophysics Data System (ADS)

    Lin, Yuxin; Liu, Hauyu Baobab; Li, Di; Zhang, Zhi-Yu; Ginsburg, Adam; Pineda, Jaime E.; Qian, Lei; Galván-Madrid, Roberto; McLeod, Anna Faye; Rosolowsky, Erik; Dale, James E.; Immer, Katharina; Koch, Eric; Longmore, Steve; Walker, Daniel; Testi, Leonardo

    2016-09-01

    We have developed an iterative procedure to systematically combine the millimeter and submillimeter images of OB cluster-forming molecular clouds, which were taken by ground-based (CSO, JCMT, APEX, and IRAM-30 m) and space telescopes (Herschel and Planck). For the seven luminous (L\\gt {10}6 L ⊙) Galactic OB cluster-forming molecular clouds selected for our analyses, namely W49A, W43-Main, W43-South, W33, G10.6-0.4, G10.2-0.3, and G10.3-0.1, we have performed single-component, modified blackbody fits to each pixel of the combined (sub)millimeter images, and the Herschel PACS and SPIRE images at shorter wavelengths. The ˜10″ resolution dust column density and temperature maps of these sources revealed dramatically different morphologies, indicating very different modes of OB cluster-formation, or parent molecular cloud structures in different evolutionary stages. The molecular clouds W49A, W33, and G10.6-0.4 show centrally concentrated massive molecular clumps that are connected with approximately radially orientated molecular gas filaments. The W43-Main and W43-South molecular cloud complexes, which are located at the intersection of the Galactic near 3 kpc (or Scutum) arm and the Galactic bar, show a widely scattered distribution of dense molecular clumps/cores over the observed ˜10 pc spatial scale. The relatively evolved sources G10.2-0.3 and G10.3-0.1 appear to be affected by stellar feedback, and show a complicated cloud morphology embedded with abundant dense molecular clumps/cores. We find that with the high angular resolution we achieved, our visual classification of cloud morphology can be linked to the systematically derived statistical quantities (i.e., the enclosed mass profile, the column density probability distribution function (N-PDF), the two-point correlation function of column density, and the probability distribution function of clump/core separations). In particular, the massive molecular gas clumps located at the center of G10.6-0.4 and

  9. The SINS/zC-SINF survey of z ∼ 2 galaxy kinematics: Evidence for powerful active galactic nucleus-driven nuclear outflows in massive star-forming galaxies

    SciTech Connect

    Förster Schreiber, N. M.; Genzel, R.; Kurk, J. D.; Lutz, D.; Tacconi, L. J.; Wuyts, S.; Bandara, K.; Buschkamp, P.; Davies, R.; Eisenhauer, F.; Lang, P.; Newman, S. F.; Burkert, A.; Carollo, C. M.; Lilly, S. J.; Cresci, G.; Daddi, E.; Mainieri, V.; Mancini, C.; and others

    2014-05-20

    We report the detection of ubiquitous powerful nuclear outflows in massive (≥10{sup 11} M {sub ☉}) z ∼ 2 star-forming galaxies (SFGs), which are plausibly driven by an active galactic nucleus (AGN). The sample consists of the eight most massive SFGs from our SINS/zC-SINF survey of galaxy kinematics with the imaging spectrometer SINFONI, six of which have sensitive high-resolution adaptive optics-assisted observations. All of the objects are disks hosting a significant stellar bulge. The spectra in their central regions exhibit a broad component in Hα and forbidden [N II] and [S II] line emission, with typical velocity FWHM ∼ 1500 km s{sup –1}, [N II]/Hα ratio ≈ 0.6, and intrinsic extent of 2-3 kpc. These properties are consistent with warm ionized gas outflows associated with Type 2 AGN, the presence of which is confirmed via independent diagnostics in half the galaxies. The data imply a median ionized gas mass outflow rate of ∼60 M {sub ☉} yr{sup –1} and mass loading of ∼3. At larger radii, a weaker broad component is detected but with lower FWHM ∼485 km s{sup –1} and [N II]/Hα ≈ 0.35, characteristic for star formation-driven outflows as found in the lower-mass SINS/zC-SINF galaxies. The high inferred mass outflow rates and frequent occurrence suggest that the nuclear outflows efficiently expel gas out of the centers of the galaxies with high duty cycles and may thus contribute to the process of star formation quenching in massive galaxies. Larger samples at high masses will be crucial in confirming the importance and energetics of the nuclear outflow phenomenon and its connection to AGN activity and bulge growth.

  10. Virilization of the Broad Line Region in Active Galactic Nuclei—connection between shifts and widths of broad emission lines

    NASA Astrophysics Data System (ADS)

    Jonić, S.; Kovačević-Dojčinović, J.; Ilić, D.; Popović, L. Č.

    2016-03-01

    We investigate the virilization of the emission lines {Hβ } and Mg II in the sample of 287 Type 1 Active Galactic Nuclei taken from the Sloan Digital Sky Survey database. We explore the connections between the intrinsic line shifts and full widths at different levels of maximal intensity. We found that: (i) {Hβ} seems to be a good virial estimator of black hole masses, and an intrinsic redshift of {Hβ} is dominantly caused by the gravitational effect, (ii) there is an anti-correlation between the redshift and width of the wings of the Mg II line, (iii) the broad Mg II line can be used as virial estimator only at 50 % of the maximal intensity, while the widths and intrinsic shifts of the line wings cannot be used for this purpose.

  11. 10 CFR Appendix D to Part 20 - United States Nuclear Regulatory Commission Regional Offices

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false United States Nuclear Regulatory Commission Regional Offices D Appendix D to Part 20 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Pt. 20, App. D Appendix D to Part 20—United States Nuclear Regulatory Commission Regional...

  12. 10 CFR Appendix D to Part 20 - United States Nuclear Regulatory Commission Regional Offices

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false United States Nuclear Regulatory Commission Regional Offices D Appendix D to Part 20 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Pt. 20, App. D Appendix D to Part 20—United States Nuclear Regulatory Commission Regional...

  13. 10 CFR Appendix D to Part 20 - United States Nuclear Regulatory Commission Regional Offices

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false United States Nuclear Regulatory Commission Regional Offices D Appendix D to Part 20 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Pt. 20, App. D Appendix D to Part 20—United States Nuclear Regulatory Commission Regional...

  14. 10 CFR Appendix D to Part 20 - United States Nuclear Regulatory Commission Regional Offices

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false United States Nuclear Regulatory Commission Regional Offices D Appendix D to Part 20 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Pt. 20, App. D Appendix D to Part 20—United States Nuclear Regulatory Commission Regional...

  15. 10 CFR Appendix D to Part 20 - United States Nuclear Regulatory Commission Regional Offices

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false United States Nuclear Regulatory Commission Regional Offices D Appendix D to Part 20 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Pt. 20, App. D Appendix D to Part 20—United States Nuclear Regulatory Commission Regional...

  16. Galactic plane gamma-radiation

    NASA Technical Reports Server (NTRS)

    Hartman, R. C.; Kniffen, D. A.; Thompson, D. J.; Fichtel, C. E.; Ogelman, H. B.; Tumer, T.; Ozel, M. E.

    1979-01-01

    Analysis of the SAS 2 data together with the COS B results shows that the distribution of galactic gamma-radiation has several similarities to that of other large-scale tracers of galactic structure. The radiation is primarily confined to a thin disc which exhibits offsets from b = 0 degrees similar to warping at radio frequencies. The principal distinction of the gamma-radiation is a stronger contrast in intensity between the region from 310 to 45 degrees in longitude and the regions away from the center that can be attributed to a variation in cosmic-ray density as a function of position in Galaxy. The diffuse galactic gamma-ray energy spectrum shows no significant variation in direction, and the spectrum seen along the plane is the same as that for the galactic component of the gamma-radiation at high altitudes. The uniformity of the galactic gamma-ray spectrum, the smooth decrease in intensity as a function of altitude, and the absence of any galactic gamma-ray sources at high altitudes indicate a diffuse origin for bulk of the galactic gamma-radiation rather than a collection of localized sources.

  17. The mid-infrared emission of narrow-line active galactic nuclei: Star formation, nuclear activity, and two populations revealed by WISE

    SciTech Connect

    Rosario, David J.; Burtscher, Leonard; Davies, Richard; Genzel, Reinhard; Lutz, Dieter; Tacconi, Linda J.

    2013-12-01

    We explore the nature of the long-wavelength mid-infrared (MIR) emission of a sample of 13,000 local Type II (narrow-line) active galactic nuclei (AGNs) from the Sloan Digital Sky Survey (SDSS) using 12 μm and 22 μm photometry from the WISE all-sky survey. In combination with FIRST 1.4 GHz photometry, we show that AGNs divide into two relatively distinct populations or 'branches' in the plane of MIR and radio luminosity. Seyfert galaxies lie almost exclusively on an MIR-bright branch (Branch A), while low-ionization nuclear emission line galaxies (LINERs) are split evenly into Branch A and the MIR-faint Branch B. We devise various tests to constrain the processes that define the branches, including a comparison to the properties of pure star-forming inactive galaxies on the MIR-radio plane. We demonstrate that the total MIR emission of objects on Branch A, including most Seyfert galaxies, is governed primarily by host star formation, with ≈15% of the 22 μm luminosity coming from AGN-heated dust. This implies that ongoing dusty star formation is a general property of Seyfert host galaxies. We show that the 12 μm broadband luminosity of AGNs on Branch A is suppressed with respect to star-forming galaxies, possibly due to the destruction of PAHs or deeper 10 μm Si absorption in AGNs. We uncover a correlation between the MIR luminosity and [O III] λ5007 luminosity in AGNs. This suggests a relationship between the star formation rate and nuclear luminosity in the AGN population, but we caution on the importance of selection effects inherent to such AGN-dominated emission-line galaxies in driving such a correlation. We highlight the MIR-radio plane as a useful tool in comparative studies of star formation and nuclear activity in AGNs.

  18. Climate and chemistry effects of a regional scale nuclear conflict

    NASA Astrophysics Data System (ADS)

    Stenke, A.; Hoyle, C. R.; Luo, B.; Rozanov, E.; Gröbner, J.; Maag, L.; Brönnimann, S.; Peter, T.

    2013-05-01

    Previous studies have highlighted the severity of detrimental effects for life on Earth after an assumed regionally limited nuclear war. These effects are caused by climatic, chemical and radiative changes persisting for up to one decade. However, so far only a very limited number of climate model simulations have been performed, giving rise to the question how realistic previous computations have been. This study uses the coupled chemistry climate model (CCM) SOCOL, which belongs to a different family of CCMs than previously used, to investigate the consequences of such a hypothetical nuclear conflict. In accordance with previous studies, the present work assumes a scenario of a nuclear conflict between India and Pakistan, each applying 50 warheads with an individual blasting power of 15 kt ("Hiroshima size") against the major population centers, resulting in the emission of tiny soot particles, which are generated in the firestorms expected in the aftermath of the detonations. Substantial uncertainties related to the calculation of likely soot emissions, particularly concerning assumptions of target fuel loading and targeting of weapons, have been addressed by simulating several scenarios, with soot emissions ranging from 1 to 12 Tg. Their high absorptivity with respect to solar radiation leads to a tremendous self-lofting of the soot particles into the strato- and mesosphere, where they remain for several years. Consequently, the model suggests Earth's surface temperatures to drop by several degrees Celsius due to the shielding of solar irradiance by the soot, indicating a major global cooling. In addition, there is a substantial reduction of precipitation lasting 5 to 10 yr after the conflict, depending on the magnitude of the initial soot release. Extreme cold spells associated with massive sea ice formation are found during Northern Hemisphere winter, which expose the continental land masses of Northern America and Eurasia to chilling coldness. In the

  19. The North Galactic Pole +30° Zone Galaxies. I. A Comparative Study of Galaxies with Different Nuclear Activity

    NASA Astrophysics Data System (ADS)

    Petrosian, Artashes; McLean, Brian; Allen, Ron; Kunth, Daniel; Leitherer, Claus

    2008-03-01

    A database containing 618 active and star-forming (A/SF) galaxies and 564 normal galaxies in a 120° × 6° wide strip crossing the north Galactic pole was constructed in order to compare the global properties of "active" galaxies against a control sample of "normal" galaxies. This database combines a literature and catalog search with new optical measurements from the Fpg (red) and Jpg (blue) band images of the STScI Digitized Sky Survey (DSS). We provide alternative names, accurate coordinates, morphological type, activity classes, red and blue apparent magnitudes, 2MASS near-infrared J-H and H-K colors, apparent diameters, axial ratios, position angles, and number counts of neighboring objects in a circle of radius 50 kpc. We also present an atlas of 103 interacting and merging systems among these galaxies. The integrated properties of A/SF and normal galaxies in this sample are compared using a multivariate factor analysis, which reveals that A/SF galaxies are objects with relatively late morphological types, and are more inclined and have bluer optical colors than normal galaxies. In this sample, all merging and interacting galaxies are A/SF objects. Star-forming galaxies are objects with relatively late morphological types, lower absolute luminosities and linear sizes, bluer colors, and higher inclination than sample X-ray or radio sources, as well as Seyfert galaxies. The near-infrared colors of the sample galaxies are independent parameters and do not correlate with activity level or any other parameter of the galaxies.

  20. Peculiarities of α-element abundances in Galactic open clusters

    NASA Astrophysics Data System (ADS)

    Marsakov, V. A.; Gozha, M. L.; Koval', V. V.; Shpigel', L. V.

    2016-01-01

    A catalog compiling the parameters of 346 open clusters, including their metallicities, positions, ages, and velocities has been composed. The elements of the Galactic orbits for 272 of the clusters have been calculated. Spectroscopic determinations of the relative abundances, [el/Fe], for 14 elements synthesized in various nuclear processes averaged over data from 109 publications are presented for 90 clusters. The compiled data indicate that the relative abundances of primary α elements (oxygen and magnesium) exhibit different dependences on metallicity, age, Galactocentric distance, and the elements of the Galactic orbits in clusters with high, elongated orbits satisfying the criterion ( Z max 2 + 4 e 2)1/2 > 0.40 and in field stars of the Galactic thin disk ( Z max is the maximum distance of the orbit from the Galactic plane in kiloparsec and e is the eccentricity of the Galactic orbit). Since no systematic effects distorting the relative abundances of the studied elements in these clusters have been found, these difference suggest real differences between clusters with high, elongated orbits and field stars. In particular, this supports the earlier conclusion, based on an analysis of the elements of the Galactic orbits, that some clusters formed as a result of interactions between high-velocity,metal-poor clouds and the interstellar mediumof theGalactic thin disk. On average, clusters with high, elongated orbits and metallicities [Fe/H] < -0.1 display lower relative abundances of the primary a elements than do field stars. The low [O, Mg/Fe] ratios of these clusters can be understood if the high-velocity clouds that gave rise to them were formed of interstellar material from regions where the star-formation rate and/or the masses of Type II supernovae were lower than near the Galactic plane. It is also shown that, on average, the relative abundances of the primary a elements are higher in relatively metal-rich clusters with high, elongated orbits than in

  1. American Nuclear Society 1994 student conference eastern region

    SciTech Connect

    1994-12-31

    This report contains abstracts from the 1994 American Nuclear Society Student Conference. The areas covered by these abstracts are: fusion and plasma physics; nuclear chemistry; radiation detection; reactor physics; thermal hydraulics; and corrosion science and waste issues.

  2. Radiogenic p-isotopes from type Ia supernova, nuclear physics uncertainties, and galactic chemical evolution compared with values in primitive meteorites

    SciTech Connect

    Travaglio, C.; Gallino, R.; Rauscher, T.; Dauphas, N.; Röpke, F. K.; Hillebrandt, W. E-mail: claudia.travaglio@b2fh.org

    2014-11-10

    The nucleosynthesis of proton-rich isotopes is calculated for multi-dimensional Chandrasekhar-mass models of Type Ia supernovae (SNe Ia) with different metallicities. The predicted abundances of the short-lived radioactive isotopes {sup 92}Nb, {sup 97,} {sup 98}Tc, and {sup 146}Sm are given in this framework. The abundance seeds are obtained by calculating s-process nucleosynthesis in the material accreted onto a carbon-oxygen white dwarf from a binary companion. A fine grid of s-seeds at different metallicities and {sup 13}C-pocket efficiencies is considered. A galactic chemical evolution model is used to predict the contribution of SN Ia to the solar system p-nuclei composition measured in meteorites. Nuclear physics uncertainties are critical to determine the role of SNe Ia in the production of {sup 92}Nb and {sup 146}Sm. We find that, if standard Chandrasekhar-mass SNe Ia are at least 50% of all SN Ia, they are strong candidates for reproducing the radiogenic p-process signature observed in meteorites.

  3. Radiogenic p-isotopes from Type Ia Supernova, Nuclear Physics Uncertainties, and Galactic Chemical Evolution Compared with Values in Primitive Meteorites

    NASA Astrophysics Data System (ADS)

    Travaglio, C.; Gallino, R.; Rauscher, T.; Dauphas, N.; Röpke, F. K.; Hillebrandt, W.

    2014-11-01

    The nucleosynthesis of proton-rich isotopes is calculated for multi-dimensional Chandrasekhar-mass models of Type Ia supernovae (SNe Ia) with different metallicities. The predicted abundances of the short-lived radioactive isotopes 92Nb, 97, 98Tc, and 146Sm are given in this framework. The abundance seeds are obtained by calculating s-process nucleosynthesis in the material accreted onto a carbon-oxygen white dwarf from a binary companion. A fine grid of s-seeds at different metallicities and 13C-pocket efficiencies is considered. A galactic chemical evolution model is used to predict the contribution of SN Ia to the solar system p-nuclei composition measured in meteorites. Nuclear physics uncertainties are critical to determine the role of SNe Ia in the production of 92Nb and 146Sm. We find that, if standard Chandrasekhar-mass SNe Ia are at least 50% of all SN Ia, they are strong candidates for reproducing the radiogenic p-process signature observed in meteorites.

  4. The nuclear X-ray source in NGC 3628: A strange active galactic nucleus or the most luminous high-mass X-ray binary known?

    NASA Technical Reports Server (NTRS)

    Dahlem, Michael; Heckman, Timothy M.; Fabbiano, Giuseppina

    1995-01-01

    After 12 years, during which its unabsorbed soft X-ray flux in the 0.1-2.0 keV band was almost constant at about f(sub x) approximately 10(exp -12) ergs/s/sq cm, the compact nuclear source in NGC 3628 was not detected in one of our ROSAT observations, with a limiting sensitivity of f(sub x) approximately 5 x 10(exp -14) ergs/s/sq cm. Our data can be explained in two ways. The source is either the most massive X-ray binary known so far, with a greater than and approximately equal to 75 solar mass black hole, or an unusual low-luminosity Active Galactic Nuclei (AGN). The X-ray spectrum is typical of a high-mass X-ray binary, while the luminosity of the source of L(sub x) is approximately equal to 10(exp 40) ergs/s is more similar to those of low-luminosity AGNs. If it is an AGN, variable obscuration might explain the observed light curve.

  5. Galactic oscillator symmetry

    NASA Technical Reports Server (NTRS)

    Rosensteel, George

    1995-01-01

    Riemann ellipsoids model rotating galaxies when the galactic velocity field is a linear function of the Cartesian coordinates of the galactic masses. In nuclear physics, the kinetic energy in the linear velocity field approximation is known as the collective kinetic energy. But, the linear approximation neglects intrinsic degrees of freedom associated with nonlinear velocity fields. To remove this limitation, the theory of symplectic dynamical symmetry is developed for classical systems. A classical phase space for a self-gravitating symplectic system is a co-adjoint orbit of the noncompact group SP(3,R). The degenerate co-adjoint orbit is the 12 dimensional homogeneous space Sp(3,R)/U(3), where the maximal compact subgroup U(3) is the symmetry group of the harmonic oscillator. The Hamiltonian equations of motion on each orbit form a Lax system X = (X,F), where X and F are elements of the symplectic Lie algebra. The elements of the matrix X are the generators of the symplectic Lie algebra, viz., the one-body collective quadratic functions of the positions and momenta of the galactic masses. The matrix F is composed from the self-gravitating potential energy, the angular velocity, and the hydostatic pressure. Solutions to the hamiltonian dynamical system on Sp(3,R)/U(3) are given by symplectic isospectral deformations. The Casimirs of Sp(3,R), equal to the traces of powers of X, are conserved quantities.

  6. Dusty cradles in a turbulent nursery: the SGR A east H II region complex at the galactic center

    SciTech Connect

    Lau, R. M.; Herter, T. L.; Adams, J. D.; Morris, M. R.

    2014-10-20

    We present imaging at 19, 25, 31, and 37 μm of the compact H II region complex G-0.02-0.07 located 6 pc in projection from the center of the Galaxy obtained with SOFIA using FORCAST. G-0.02-0.07 contains three compact H II regions (A, B, and C) and one ultra-compact H II region (D). Our observations reveal the presence of two faint, infrared sources located 23'' and 35'' to the east of region C (FIRS 1 and 2) and detect dust emission in two of the three 'ridges' of ionized gas west of region A. The 19/37 color temperature and 37 μm optical depth maps of regions A-C are used to characterize the dust energetics and morphology. Regions A and B exhibit average 19/37 color temperatures of ∼105 K, and regions C and D exhibit color temperatures of ∼115 K and ∼130 K, respectively. Using the DustEM code, we model the SEDs of regions A-D and FIRS 1, all of which require populations of very small, transiently heated grains and large, equilibrium-heated grains. We also require the presence of polycyclic aromatic hydrocarbons in regions A-C in order to fit the 3.6, 4.5, 5.8, and 8.0 μm fluxes observed by Spitzer/IRAC. The location of the heating source for region A is determined by triangulation from distances and temperatures derived from DustEM models fit to SEDs of three different points around the region, and it is found to be displaced to the northeast of the center of curvature near the color temperature peak. Based on total luminosity, expected 1.90 μm fluxes, and proximity to the mid-IR color temperature peaks, we identify heating source candidates for regions A, B, and C. However, for region D, the observed fluxes at 1.87 and 1.90 μm of the previously proposed ionizing star are a factor of ∼40 times too bright to be the heating source and hence is likely just a star lying along the line of sight toward region D.

  7. Climate and chemistry effects of a regional scale nuclear conflict

    NASA Astrophysics Data System (ADS)

    Stenke, A.; Hoyle, C. R.; Luo, B.; Rozanov, E.; Gröbner, J.; Maag, L.; Brönnimann, S.; Peter, T.

    2013-10-01

    Previous studies have highlighted the severity of detrimental effects for life on earth after an assumed regionally limited nuclear war. These effects are caused by climatic, chemical and radiative changes persisting for up to one decade. However, so far only a very limited number of climate model simulations have been performed, giving rise to the question how realistic previous computations have been. This study uses the coupled chemistry climate model (CCM) SOCOL, which belongs to a different family of CCMs than previously used, to investigate the consequences of such a hypothetical nuclear conflict. In accordance with previous studies, the present work assumes a scenario of a nuclear conflict between India and Pakistan, each applying 50 warheads with an individual blasting power of 15 kt ("Hiroshima size") against the major population centers, resulting in the emission of tiny soot particles, which are generated in the firestorms expected in the aftermath of the detonations. Substantial uncertainties related to the calculation of likely soot emissions, particularly concerning assumptions of target fuel loading and targeting of weapons, have been addressed by simulating several scenarios, with soot emissions ranging from 1 to 12 Tg. Their high absorptivity with respect to solar radiation leads to a rapid self-lofting of the soot particles into the strato- and mesosphere within a few days after emission, where they remain for several years. Consequently, the model suggests earth's surface temperatures to drop by several degrees Celsius due to the shielding of solar irradiance by the soot, indicating a major global cooling. In addition, there is a substantial reduction of precipitation lasting 5 to 10 yr after the conflict, depending on the magnitude of the initial soot release. Extreme cold spells associated with an increase in sea ice formation are found during Northern Hemisphere winter, which expose the continental land masses of North America and Eurasia to a

  8. Gamma ray constraints on the Galactic supernova rate

    NASA Technical Reports Server (NTRS)

    Hartmann, D.; The, L.-S.; Clayton, Donald D.; Leising, M.; Mathews, G.; Woosley, S. E.

    1991-01-01

    We perform Monte Carlo simulations of the expected gamma ray signatures of Galactic supernovae of all types to estimate the significance of the lack of a gamma ray signal due to supernovae occurring during the last millenium. Using recent estimates of the nuclear yields, we determine mean Galactic supernova rates consistent with the historic supernova record and the gamma ray limits. Another objective of these calculations of Galactic supernova histories is their application to surveys of diffuse Galactic gamma ray line emission.

  9. SAS-2 galactic gamma ray results, 1

    NASA Technical Reports Server (NTRS)

    Thompson, D. J.; Fichtel, C. E.; Hartman, R. C.; Kniffen, D. A.; Bignami, G. F.; Lamb, R. C.; Oegelman, H.; Oezel, M. E.; Tuemer, T.

    1976-01-01

    Continuing analysis of the data from the SAS-2 high energy gamma-ray experiment has produced an improved picture of the sky at photon energies above 35 MeV. On a large scale, the diffuse emission from the galactic plane is the dominant feature observed by SAS-2. This galactic plane emission is most intense between galactic longitude 310 and 45 deg, corresponding to a region within 7kpc of the galactic center. Within the high-intensity region, SAS-2 observes peaks around galactic longitudes 315 deg, 330 deg, 345 deg, 0 deg, and 35 deg. These peaks appear to be correlated with such galactic features and components as molecular hydrogen, atomic hydrogen, magnetic fields, cosmic ray concentrations, and photon fields.

  10. THE ORIGIN OF THE 6.4 keV LINE EMISSION AND H{sub 2} IONIZATION IN THE DIFFUSE MOLECULAR GAS OF THE GALACTIC CENTER REGION

    SciTech Connect

    Dogiel, V. A.; Chernyshov, D. O.; Tatischeff, V.; Terrier, R.

    2013-07-10

    We investigate the origin of the diffuse 6.4 keV line emission recently detected by Suzaku and the source of H{sub 2} ionization in the diffuse molecular gas of the Galactic center (GC) region. We show that Fe atoms and H{sub 2} molecules in the diffuse interstellar medium of the GC are not ionized by the same particles. The Fe atoms are most likely ionized by X-ray photons emitted by Sgr A* during a previous period of flaring activity of the supermassive black hole. The measured longitudinal intensity distribution of the diffuse 6.4 keV line emission is best explained if the past activity of Sgr A* lasted at least several hundred years and released a mean 2-100 keV luminosity {approx}> 10{sup 38} erg s{sup -1}. The H{sub 2} molecules of the diffuse gas cannot be ionized by photons from Sgr A*, because soft photons are strongly absorbed in the interstellar gas around the central black hole. The molecular hydrogen in the GC region is most likely ionized by low-energy cosmic rays, probably protons rather than electrons, whose contribution into the diffuse 6.4 keV line emission is negligible.

  11. Galactic Evolution

    NASA Astrophysics Data System (ADS)

    Brekke, Stewart

    2013-04-01

    All galaxies began as spiral galaxies. The early universe began with sets of two or more pre-galactic arms orbiting each other. As gravitational attraction between the arms took effect, the fore-sections of the arms tangentially collided forming spiral galaxies when they attached with the orbital motion of the arms being converted to the rotational motion of the newly formed spiral galaxies or (Iφ)arm1+ (Iφ)arm2+ ...+ (Iφ)armn= (Iφ)galaxy. If the centripetal force on the arms is more than the gravitational force on the arms, the spiral galaxy remains a spiral galaxy i.e. mv^2/r>=Gmarmmgalaxy/r^2. If the galaxy is slowly rotating, the spiral arms collapse into the body of the galaxy because the gravitational force is greater than the centripetal force on the arms and an elliptical galaxy is formed i.e. mv^2/r < Gmarmsmgalaxy/r^2.

  12. TESTING 24 {mu}m AND INFRARED LUMINOSITY AS STAR FORMATION TRACERS FOR GALACTIC STAR-FORMING REGIONS

    SciTech Connect

    Vutisalchavakul, Nalin; Evans, Neal J. II

    2013-03-10

    We have tested some relations for star formation rates used in extragalactic studies for regions within the Galaxy. In nearby molecular clouds, where the initial mass function is not fully sampled, the dust emission at 24 {mu}m greatly underestimates star formation rates (by a factor of 100 on average) when compared to star formation rates determined from counting young stellar objects. The total infrared emission does no better. In contrast, the total far-infrared method agrees within a factor of two on average with star formation rates based on radio continuum emission for massive, dense clumps that are forming enough massive stars to have L{sub TIR} exceed 10{sup 4.5} L{sub Sun }. The total infrared and 24 {mu}m also agree well with each other for both nearby, low-mass star-forming regions and the massive, dense clump regions.

  13. Self-shadowing Effects of Slim Accretion Disks in Active Galactic Nuclei: The Diverse Appearance of the Broad-line Region

    NASA Astrophysics Data System (ADS)

    Wang, Jian-Min; Qiu, Jie; Du, Pu; Ho, Luis C.

    2014-12-01

    Supermassive black holes in active galactic nuclei (AGNs) undergo a wide range of accretion rates, which lead to diversity of appearance. We consider the effects of anisotropic radiation from accretion disks on the broad-line region (BLR) from the Shakura-Sunyaev regime to slim disks with super-Eddington accretion rates. The geometrically thick funnel of the inner region of slim disks produces strong self-shadowing effects that lead to very strong anisotropy of the radiation field. We demonstrate that the degree of anisotropy of the radiation fields grows with increasing accretion rate. As a result of this anisotropy, BLR clouds receive different spectral energy distributions depending on their location relative to the disk, resulting in the diverse observational appearance of the BLR. We show that the self-shadowing of the inner parts of the disk naturally produces two dynamically distinct regions of the BLR, depending on accretion rate. These two regions manifest themselves as kinematically distinct components of the broad Hβ line profile with different line widths and fluxes, which jointly account for the Lorentzian profile generally observed in narrow-line Seyfert 1 galaxies. In the time domain, these two components are expected to reverberate with different time lags with respect to the varying ionizing continuum, depending on the accretion rate and the viewing angle of the observer. The diverse appearance of the BLR due to the anisotropic ionizing energy source can be tested by reverberation mapping of Hβ and other broad emission lines (e.g., Fe II), providing a new tool to diagnose the structure and dynamics of the BLR. Other observational consequences of our model are also explored.

  14. Self-shadowing effects of slim accretion disks in active galactic nuclei: the diverse appearance of the broad-line region

    SciTech Connect

    Wang, Jian-Min; Qiu, Jie; Du, Pu; Ho, Luis C.

    2014-12-10

    Supermassive black holes in active galactic nuclei (AGNs) undergo a wide range of accretion rates, which lead to diversity of appearance. We consider the effects of anisotropic radiation from accretion disks on the broad-line region (BLR) from the Shakura-Sunyaev regime to slim disks with super-Eddington accretion rates. The geometrically thick funnel of the inner region of slim disks produces strong self-shadowing effects that lead to very strong anisotropy of the radiation field. We demonstrate that the degree of anisotropy of the radiation fields grows with increasing accretion rate. As a result of this anisotropy, BLR clouds receive different spectral energy distributions depending on their location relative to the disk, resulting in the diverse observational appearance of the BLR. We show that the self-shadowing of the inner parts of the disk naturally produces two dynamically distinct regions of the BLR, depending on accretion rate. These two regions manifest themselves as kinematically distinct components of the broad Hβ line profile with different line widths and fluxes, which jointly account for the Lorentzian profile generally observed in narrow-line Seyfert 1 galaxies. In the time domain, these two components are expected to reverberate with different time lags with respect to the varying ionizing continuum, depending on the accretion rate and the viewing angle of the observer. The diverse appearance of the BLR due to the anisotropic ionizing energy source can be tested by reverberation mapping of Hβ and other broad emission lines (e.g., Fe II), providing a new tool to diagnose the structure and dynamics of the BLR. Other observational consequences of our model are also explored.

  15. On the relative importance of different microphysics on the D-type expansion of galactic H II regions

    NASA Astrophysics Data System (ADS)

    Haworth, T. J.; Harries, T. J.; Acreman, D. M.; Bisbas, T. G.

    2015-11-01

    Radiation hydrodynamics (RHD) simulations are used to study many astrophysical phenomena; however, they require the use of simplified radiation transport and thermal prescriptions to reduce computational cost. In this paper, we present a systematic study of the importance of microphysical processes in RHD simulations using the example of D-type H II region expansion. We compare the simplest hydrogen-only models with those that include: ionization of H, He, C, N, O, S and Ne, different gas metallicity, non-LTE metal-line-blanketed stellar spectral models of varying metallicity, radiation pressure, dust and treatment of photodissociation regions. Each of these processes is explicitly treated using modern numerical methods rather than parametrization. In line with expectations, changes due to microphysics in either the effective number of ionizing photons or the thermal structure of the gas lead to differences in D-type expansion. In general, we find that more realistic calculations lead to the onset of D-type expansion at smaller radii and a slower subsequent expansion. Simulations of star-forming regions using simplified microphysics are therefore likely overestimating the strength of radiative feedback. We find that both variations in gas metallicity and the inclusion of dust can affect the ionization front evolution at the 10-20 per cent level over 500 kyr, which could substantially modify the results of simplified 3D models including feedback. Stellar metallicity, radiation pressure and the inclusion of photodissociation regions are all less-significant effects at the 1 per cent level or less, rendering them of minor importance in the modelling the dynamical evolution of H II regions.

  16. ATOMIC HYDROGEN IN A GALACTIC CENTER OUTFLOW

    SciTech Connect

    McClure-Griffiths, N. M.; Green, J. A.; Hill, A. S.; Lockman, F. J.; Dickey, J. M.; Gaensler, B. M.; Green, A. J.

    2013-06-10

    We describe a population of small, high-velocity, atomic hydrogen clouds, loops, and filaments found above and below the disk near the Galactic center. The objects have a mean radius of 15 pc, velocity widths of {approx}14 km s{sup -1}, and are observed at |z| heights up to 700 pc. The velocity distribution of the clouds shows no signature of Galactic rotation. We propose a scenario where the clouds are associated with an outflow from a central star-forming region at the Galactic center. We discuss the clouds as entrained material traveling at {approx}200 km s{sup -1} in a Galactic wind.

  17. A study of four galactic small H II regions: Searching for spontaneous and sequential star formation scenarios

    NASA Astrophysics Data System (ADS)

    Kang, Sung-Ju

    This thesis describes observational studies of four small star-forming H II regions (KR 7, KR 81, KR 120 and KR 140) and star-formation scenario associated with the Young Stellar Objects (YSOs) in each region. In addition to that, we also present an analysis of HCO+ (J=3→2) and H13CO+ (J=3→2) observations of the Massive (M ˜ 20 M[special character omitted] ) submillimeter/infrared source IRAS 01202+6133 located on the periphery of the H II region. In this research, we improved existing 1-D radiative transfer model for a collapsing core that happens in the early phase -- Class I protostar -- of star formation. The molecular gas surrounding an H II region is thought to be a place where star formation can be induced. We selected four small H II region in order to minimize the feedbacks and dynamics from multiple exciting sources. These regions are very young and ionized by the single O or B spectral type stars. A space based telescope Wide-field Infrared Survey Explorer (WISE) used for identifying and classifying the YSOs population surrounding a sample of H II regions. First, we used WISE data from AllWISE catalog with some constrains such as spatial coordinates, signal-to-noise ratio and contaminations. After we retrieved sources from catalog in each region, we classified YSOs with two different methods; color-color diagram and spectral index (alpha). Based on the color-color diagram using WISE 3.4 mum, 4.6 mum and 12 mum bands, we classified the YSOs as Class I, Class II and using 3.4 mum, 4.6 mum and 22 mum, we were able to classify Transition Disks and Class III YSOs. 2MASS and WISE combined color-color diagram also used in order to compare the classification only use of WISE color-color diagram. Considering a reddening effect from 2MASS Ks band, the classification from both WISE only and 2MASS, WISE combined color-colordiagram. A spectral index (alpha) also can be used as classifying YSOs. Based on the WISE magnitude, spectral index (alpha) can be derived

  18. SOAR Near-Infrared and Optical Survey of OIf* and OIf*/WN Stars in the Periphery of Galactic Massive Star Forming Regions

    NASA Astrophysics Data System (ADS)

    Roman-Lopes, A.; Franco, G. A. P.; Sanmartin, D.

    In this contribution we present some preliminary results obtained from a SOAR-Goodman optical spectroscopic survey aimed to confirm the OIf* - OIf*/WN nature of a sample of Galactic candidates that were previously confirmed as massive stars based on near-infrared spectra taken with OSIRIS at SOAR. With only a few of such stars known in the Galaxy to date, our study significantly contributes to improve the number of known Galactic O2If* stars, as well as almost doubling the number of known members of the galactic sample of the rare type OIf*/WN.

  19. Constraining UV continuum slopes of active galactic nuclei with cloudy models of broad-line region extreme-ultraviolet emission lines

    SciTech Connect

    Moloney, Joshua; Michael Shull, J. E-mail: michael.shull@colorado.edu

    2014-10-01

    Understanding the composition and structure of the broad-line region (BLR) of active galactic nuclei (AGNs) is important for answering many outstanding questions in supermassive black hole evolution, galaxy evolution, and ionization of the intergalactic medium. We used single-epoch UV spectra from the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope to measure EUV emission-line fluxes from four individual AGNs with 0.49 ≤ z ≤ 0.64, two AGNs with 0.32 ≤ z ≤ 0.40, and a composite of 159 AGNs. With the CLOUDY photoionization code, we calculated emission-line fluxes from BLR clouds with a range of density, hydrogen ionizing flux, and incident continuum spectral indices. The photoionization grids were fit to the observations using single-component and locally optimally emitting cloud (LOC) models. The LOC models provide good fits to the measured fluxes, while the single-component models do not. The UV spectral indices preferred by our LOC models are consistent with those measured from COS spectra. EUV emission lines such as N IV λ765, O II λ833, and O III λ834 originate primarily from gas with electron temperatures between 37,000 K and 55,000 K. This gas is found in BLR clouds with high hydrogen densities (n {sub H} ≥ 10{sup 12} cm{sup –3}) and hydrogen ionizing photon fluxes (Φ{sub H} ≥ 10{sup 22} cm{sup –2} s{sup –1}).

  20. Modeling the Destruction and Survival of PAHs in Astrophysical Regions: from Low-metallicity Galaxies to Elliptical Galaxies and Galactic Halos

    NASA Astrophysics Data System (ADS)

    Li, Aigen

    2006-05-01

    The 3.3, 6.2, 7.7, 8.6 and 11.3 micron emission features of polycyclic aromatic hydrocarbon (PAH) molecules have been seen in a wide variety of Galactic and extragalactic objects. However, the PAH features are weak or absent in low-metallicity galaxies and AGN, as generally interpreted as the destruction of PAHs by hard UV photons in metal-poor galaxies or by extreme UV and soft X-ray photons in AGN. On the other hand, the PAH emission features have recently been detected in elliptical galaxies, tidal dwarf galaxies, galaxy halos, and distant galaxies at redshift >=2. However, it is not clear how PAHs can survive in elliptical galaxies containing X-ray emitting hot gas where PAHs are expected to be easily destroyed through sputtering by hot plasma ions. It is also not clear how PAHs get ``levitated'' and survive from galactic plane to galaxy halo where the physical conditions are similar to those of elliptical galaxies. We propose to study the destruction of PAHs (1) by UV photons in low-metallicity galaxies, (2) by extreme UV and X-ray photons in AGN, (3) by intense UV radiation in regions with strong star-forming activities, and (4) through sputtering by plasma ions in hot gas. This will allow us, by the first time, to quantitatively investigate the deficiency or lack of PAHs in AGN and low-metallicity galaxies, as well as the survivability of PAHs in elliptical galaxies, galaxy halo, and superwind, and the method of using the IRAC 8 micron photometry as a tracer of star formation rates. This program will create a web-based ``library'' of the destruction rates of PAHs by UV and X-ray photons as a function of size, intensity and hardness of the radiation field, and the sputtering rates of PAHs by plasma ions as a function of size, gas density and temperature. This library will be made publicly available to the astronomical community by May 2007 on the internet at http://www.missouri.edu/~lia/.

  1. Western Region American Nuclear Society regional student conference, April 12-14, 1985

    SciTech Connect

    Not Available

    1985-01-01

    Abstracts of papers presented at the conference are contained in this proceedings. Topics of technical sessions included fusion and space reactors, numerical and computer modeling, nuclear medicine and radiation effects, and general nuclear technology. (GHT)

  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. A lack of classical Cepheids in the inner part of the Galactic disc

    NASA Astrophysics Data System (ADS)

    Matsunaga, Noriyuki; Feast, Michael W.; Bono, Giuseppe; Kobayashi, Naoto; Inno, Laura; Nagayama, Takahiro; Nishiyama, Shogo; Matsuoka, Yoshiki; Nagata, Tetsuya

    2016-10-01

    Recent large-scale infrared surveys have been revealing stellar populations in the inner Galaxy seen through strong interstellar extinction in the disc. In particular, classical Cepheids with their period-luminosity and period-age relations are useful tracers of Galactic structure and evolution. Interesting groups of Cepheids reported recently include four Cepheids in the nuclear stellar disc (NSD), about 200 pc around the Galactic Centre, found by Matsunaga et al. and those spread across the inner part of the disc reported by Dékány and collaborators. We here report our discovery of nearly 30 classical Cepheids towards the bulge region, some of which are common with Dékány et al., and discuss the large impact of the reddening correction on distance estimates for these objects. Assuming that the four Cepheids in the NSD are located at the distance of the Galactic Centre and that the near-infrared extinction law, i.e. wavelength dependency of the interstellar extinction, is not systematically different between the NSD and other bulge lines of sight, most of the other Cepheids presented here are located significantly further than the Galactic Centre. This suggests a lack of Cepheids in the inner 2.5 kpc region of the Galactic disc except the NSD. Recent radio observations show a similar distribution of star-forming regions.

  4. A climatological study of the relations among solar activity, galactic cosmic ray and precipitation on various regions over the globe

    NASA Astrophysics Data System (ADS)

    Bal, Sourabh; Bose, M.

    2010-04-01

    We apply Fourier and wavelet analyses to the precipitation and sunspot numbers in the time series (1901-2000) over Australia (27°S, 133°E), Canada (60°N, 95°W), Ethiopia (8°N, 38°E), Greenland (72°N, 40°W), United Kingdom (54°N, 2°W), India (20°N, 77°E), Iceland (65°N, 18°W), Japan (36°N, 138°E), United States (38°N, 97°W), South Africa (29°S, 24°E) and Russia (60°N, 100°E). Correlation analyses were also performed to find any relation among precipitation, sunspot numbers, temperature, and cloud-cover at the same spatial and temporal scale. Further correlations were also performed between precipitation with electron and proton fluence at the time interval, 1987-2006. All these parameters were considered in annual and seasonal scales. Though correlation study between precipitation and other parameters do not hint any linear relation, still the Fourier and wavelet analyses give an idea of common periodicities. The 9-11 year periodicity of sunspot numbers calculated by Fourier transform is also confirmed by wavelet transform in annual scale. Similarly, wavelet analysis for precipitation also supports the short periods at 2-5 years which is verified by Fourier transform in discontinuous time over different geographic regions.

  5. CO mapping of the nuclear region of NGC 6946 and IC 342 with Nobeyama millimeter array

    NASA Technical Reports Server (NTRS)

    Ishizuki, Sumio; Kawabe, Ryohei; Okumura, Sachiko K.; Morita, Koh-Ichiro; Ishiguro, Masato

    1990-01-01

    CO observations of nearby galaxies with nuclear active star forming regions (and starburst galaxies) with angular resolutions around 7 seconds revealed that molecular bars with a length of a few kiloparsecs have been formed in the central regions of the galaxies. The molecular bar is interpreted as part of shock waves induced by an oval or barred potential field. By shock dissipation or dissipative cloud-cloud collisions, the molecular gas gains an infall motion and the nuclear star formation activity is fueled. But the distribution and kinematics of the molecular gas in the nuclear regions, which are sites of active star formation, remain unknown. Higher angular resolutions are needed to investigate the gas in the nuclear regions. Researchers made aperture synthesis observations of the nuclear region of the late-type spiral galaxies NGC 6946 and IC 342 with resolutions of 7.6 seconds x 4.2 seconds (P.A. = 147 deg) and 2.4 seconds x 2.3 seconds (P.A. = 149 deg), respectively. The distances to NGC 6496 and IC 342 are assumed to be 5.5 Mpc and 3.9 Mpc, respectively. Researchers have found 100-300 pc nuclear gas disk and ring inside a few kpc molecular gas bars. Researchers present the results of the observations and propose a possible mechanism of active star formation in the nuclear region.

  6. Multi-phase Nature of a Radiation-driven Fountain with Nuclear Starburst in a Low-mass Active Galactic Nucleus

    NASA Astrophysics Data System (ADS)

    Wada, Keiichi; Schartmann, Marc; Meijerink, Rowin

    2016-09-01

    The structures and dynamics of molecular, atomic, and ionized gases are studied around a low-luminosity active galactic nucleus (AGN) with a small (2× {10}6{M}ȯ ) black hole using three-dimensional (3D) radiation–hydrodynamic simulations. We studied, for the first time, the non-equilibrium chemistry for the X-ray-dominated region in the “radiation-driven fountain” with supernova feedback. A double hollow cone structure is naturally formed without postulating a thick “torus” around a central source. The cone is occupied with an inhomogeneous, diffuse ionized gas and surrounded by a geometrically thick (h/r≳ 1) atomic gas. Dense molecular gases are distributed near the equatorial plane, and energy feedback from supernovae enhances their scale height. Molecular hydrogen exists in a hot phase (>1000 K) as well as in a cold (\\lt 100 {{K}}), dense (\\gt {10}3 {{cm}}-3) phase. The velocity dispersion of H2 in the vertical direction is comparable to the rotational velocity, which is consistent with near-infrared observations of nearby Seyfert galaxies. Using 3D radiation transfer calculations for the dust emission, we find polar emission in the mid-infrared band (12 μm), which is associated with bipolar outflows, as suggested in recent interferometric observations of nearby AGNs. If the viewing angle for the nucleus is larger than 75°, the spectral energy distribution is consistent with that of the Circinus galaxy. The multi-phase interstellar medium observed in optical/infrared and X-ray observations is also discussed.

  7. Multi-phase Nature of a Radiation-driven Fountain with Nuclear Starburst in a Low-mass Active Galactic Nucleus

    NASA Astrophysics Data System (ADS)

    Wada, Keiichi; Schartmann, Marc; Meijerink, Rowin

    2016-09-01

    The structures and dynamics of molecular, atomic, and ionized gases are studied around a low-luminosity active galactic nucleus (AGN) with a small (2× {10}6{M}⊙ ) black hole using three-dimensional (3D) radiation-hydrodynamic simulations. We studied, for the first time, the non-equilibrium chemistry for the X-ray-dominated region in the “radiation-driven fountain” with supernova feedback. A double hollow cone structure is naturally formed without postulating a thick “torus” around a central source. The cone is occupied with an inhomogeneous, diffuse ionized gas and surrounded by a geometrically thick (h/r≳ 1) atomic gas. Dense molecular gases are distributed near the equatorial plane, and energy feedback from supernovae enhances their scale height. Molecular hydrogen exists in a hot phase (>1000 K) as well as in a cold (\\lt 100 {{K}}), dense (\\gt {10}3 {{cm}}-3) phase. The velocity dispersion of H2 in the vertical direction is comparable to the rotational velocity, which is consistent with near-infrared observations of nearby Seyfert galaxies. Using 3D radiation transfer calculations for the dust emission, we find polar emission in the mid-infrared band (12 μm), which is associated with bipolar outflows, as suggested in recent interferometric observations of nearby AGNs. If the viewing angle for the nucleus is larger than 75°, the spectral energy distribution is consistent with that of the Circinus galaxy. The multi-phase interstellar medium observed in optical/infrared and X-ray observations is also discussed.

  8. The Galactic Center Seen Through the Precise, Multiplexed Eye of JWST

    NASA Astrophysics Data System (ADS)

    Lu, Jessica R.

    2013-01-01

    The Galactic center harbors the closest supermassive black hole and contains warm, turbulent molecular clouds, dense stellar populations, and some of the most active star forming regions in the Milky Way. These unique conditions make the Galactic Center a compelling target for understanding how star formation varies with environment, how nuclear star clusters in galaxies evolve, and how supermassive black holes influence their surroundings. Detailed studies of the Galactic center have previously been conducted with ground-based telescopes equipped with adaptive optics in pencil-beam studies. However, Galactic center studies can be dramatically expanded with JWST's combination of large fields-of-view (FOV) and high spatial resolution in the infrared. Of particular relevance for the Galactic Center are NIRCam's suite of narrow-band imaging filters and NIRSpec's IFU spectrograph. The narrow-band imaging should provide precise astrometry, rough spectral types, and emission line maps for ~50,000 stars within a 2' x 2' FOV, while follow up IFU spectroscopy will give precise types and radial velocities for the most interesting subsets of stars. Potential results include: (1) counting the intermediate age red and yellow supergiants that will give information about the recent star formation history; (2) measuring the initial mass function below 1 Msun and studying young stellar objects in known and new young star clusters; (3) using 3D dynamics to model the kinematic evolution of the entire nuclear cluster, find hypervelocity stars, and trace the orbits of gas features and clusters in the region. Galactic Center observations with JWST will give us a more complete picture of the gas, stars, black hole, and their interactions in this dynamic region.

  9. THREE-DIMENSIONAL STELLAR KINEMATICS AT THE GALACTIC CENTER: MEASURING THE NUCLEAR STAR CLUSTER SPATIAL DENSITY PROFILE, BLACK HOLE MASS, AND DISTANCE

    SciTech Connect

    Do, T.; Martinez, G. D.; Bullock, J.; Kaplinghat, M.; Peter, A. H. G.; Yelda, S.; Ghez, A.; Phifer, K.; Lu, J. R.

    2013-12-10

    We present three-dimensional (3D) kinematic observations of stars within the central 0.5 pc of the Milky Way (MW) nuclear star cluster (NSC) using adaptive optics imaging and spectroscopy from the Keck telescopes. Recent observations have shown that the cluster has a shallower surface density profile than expected for a dynamically relaxed cusp, leading to important implications for its formation and evolution. However, the true 3D profile of the cluster is unknown due to the difficulty in de-projecting the stellar number counts. Here, we use spherical Jeans modeling of individual proper motions and radial velocities to constrain, for the first time, the de-projected spatial density profile, cluster velocity anisotropy, black hole mass (M {sub BH}), and distance to the Galactic center (R {sub 0}) simultaneously. We find that the inner stellar density profile of the late-type stars, ρ(r)∝r {sup –γ}, have a power law slope γ=0.05{sub −0.60}{sup +0.29}, much more shallow than the frequently assumed Bahcall-Wolf slope of γ = 7/4. The measured slope will significantly affect dynamical predictions involving the cluster, such as the dynamical friction time scale. The cluster core must be larger than 0.5 pc, which disfavors some scenarios for its origin. Our measurement of M{sub BH}=5.76{sub −1.26}{sup +1.76}×10{sup 6} M {sub ☉} and R{sub 0}=8.92{sub −0.55}{sup +0.58} kpc is consistent with that derived from stellar orbits within 1'' of Sgr A*. When combined with the orbit of S0-2, the uncertainty on R {sub 0} is reduced by 30% (8.46{sub −0.38}{sup +0.42} kpc). We suggest that the MW NSC can be used in the future in combination with stellar orbits to significantly improve constraints on R {sub 0}.

  10. Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. V. A New Size-Luminosity Scaling Relation for the Broad-line Region

    NASA Astrophysics Data System (ADS)

    Du, Pu; Lu, Kai-Xing; Zhang, Zhi-Xiang; Huang, Ying-Ke; Wang, Kai; Hu, Chen; Qiu, Jie; Li, Yan-Rong; Fan, Xu-Liang; Fang, Xiang-Er; Bai, Jin-Ming; Bian, Wei-Hao; Yuan, Ye-Fei; Ho, Luis C.; Wang, Jian-Min; SEAMBH Collaboration

    2016-07-01

    This paper reports results of the third-year campaign of monitoring super-Eddington accreting massive black holes (SEAMBHs) in active galactic nuclei (AGNs) between 2014 and 2015. Ten new targets were selected from the quasar sample of the Sloan Digital Sky Survey (SDSS), which have generally been more luminous than the SEAMBH candidates in the last two years. Hβ lags ({τ }{{H}β }) in five of the 10 quasars have been successfully measured in this monitoring season. We find that the lags are generally shorter, by large factors, than those of objects with same optical luminosity, in light of the well-known R H β-L 5100 relation. The five quasars have dimensionless accretion rates of \\dot{{M}\\quad }=10-103. Combining these with measurements of the previous SEAMBHs, we find that the reduction of Hβ lags depends tightly on accretion rates, {τ }{{H}β }/{τ }R-L\\propto {\\dot{{M}}}-0.42, where {τ }R-L is the Hβ lag from the normal R H β-L 5100 relation. Fitting 63 mapped AGNs, we present a new scaling relation for the broad-line region: {R}{{H}β }={α }1{{\\ell }}44{β 1} {min} [1,{(\\dot{{M}}/{\\dot{{M}}}c)}-{γ 1}], where {{\\ell }}44={L}5100/{10}44 {erg} {{{s}}}-1 is the 5100 Å continuum luminosity, and the coefficients are {α }1={29.6}-2.8+2.7 lt-day, {β }1={0.56}-0.03+0.03, {γ }1={0.52}-0.16+0.33, and {\\dot{{M}}}c={11.19}-6.22+2.29. This relation is applicable to AGNs over a wide range of accretion rates, from 10-3 to 103. Implications of this new relation are briefly discussed.

  11. [Fe II] 1.64 μm IMAGING OBSERVATIONS OF THE OUTFLOW FEATURES AROUND ULTRACOMPACT H II REGIONS IN THE FIRST GALACTIC QUADRANT

    SciTech Connect

    Shinn, Jong-Ho; Kim, Kee-Tae; Lee, Jae-Joon; Kyeong, Jaemann; Hwang, Narae; Park, Byeong-Gon; Lee, Yong-Hyun; Kim, Hyun-Jeong; Koo, Bon-Chul; Pyo, Tae-Soo

    2014-09-01

    We present [Fe II] 1.644 μm features around ultracompact H II regions (UCHIIs) found on a quest for the ''footprint'' outflow features of UCHIIs—the features produced by outflowing materials ejected during an earlier, active accretion phase of massive young stellar objects (MYSOs). We surveyed 237 UCHIIs in the first Galactic quadrant, employing the CORNISH UCHII catalog and UWIFE data, which is an imaging survey in [Fe II] 1.644 μm performed with UKIRT-WFCAM under ∼0.''8 seeing conditions. The [Fe II] features were found around five UCHIIs, one of which was less plausible. We interpret the [Fe II] features to be shock-excited by outflows from YSOs and estimate the outflow mass-loss rates from the [Fe II] flux which are ∼1 × 10{sup –6}-4 × 10{sup –5} M {sub ☉} yr{sup –1}. We propose that the [Fe II] features might be the ''footprint'' outflow features, but more studies are required to clarify whether or not this is the case. This is based on the morphological relation between the [Fe II] and 5 GHz radio features, the outflow mass-loss rate, the travel time of the [Fe II] features, and the existence of several YSO candidates near the UCHIIs. The UCHIIs accompanying the [Fe II] features have relatively higher peak flux densities. The fraction of UCHIIs accompanying the [Fe II] features, 5/237, is small when compared to the ∼90% detection rate of high-velocity CO gas around UCHIIs. We discuss some possible explanations for the low detection rate.

  12. Dusty Structure Around Type-I Active Galactic Nuclei: Clumpy Torus Narrow-line Region and Near-nucleus Hot Dust

    NASA Astrophysics Data System (ADS)

    Mor, Rivay; Netzer, Hagai; Elitzur, Moshe

    2009-11-01

    We fitted Spitzer/IRS ~ 2-35 μm spectra of 26 luminous quasi-stellar objects in an attempt to define the main emission components. Our model has three major components: a clumpy torus, dusty narrow-line region (NLR) clouds, and a blackbody-like dust. The models utilize the clumpy torus of Nenkova et al. and are the first to allow its consistent check in type-I active galactic nuclei (AGNs). Single torus models and combined torus-NLR models fail to fit the spectra of most sources, but three-component models adequately fit the spectra of all sources. We present torus inclination, cloud distribution, covering factor, and torus mass for all sources and compare them with bolometric luminosity, black hole mass, and accretion rate. The torus mass is found to be correlated with the bolometric luminosity of the sources. Torus-covering factor may also be (anti-)correlated, if some possibly anomalous points are omitted. We find that a substantial amount of the ~2-7 μm radiation originates from a hot dust component, which is likely situated in the innermost part of the torus. The luminosity radiated by this component and its covering factor are comparable to those of the torus. We quantify the emission by the NLR clouds and estimate their distance from the center. The distances are ~700 times larger than the dust sublimation radius, and the NLR-covering factor is about 0.07. The total covering factor by all components is in good agreement with the known AGN type-I:type-II ratio.

  13. NuSTAR Hard X-Ray Survey of the Galactic Center Region I: Hard X-Ray Morphology and Spectroscopy of the Diffuse Emission

    NASA Astrophysics Data System (ADS)

    Mori, Kaya; Hailey, Charles J.; Krivonos, Roman; Hong, Jaesub; Ponti, Gabriele; Bauer, Franz; Perez, Kerstin; Nynka, Melania; Zhang, Shuo; Tomsick, John A.; Alexander, David M.; Baganoff, Frederick K.; Barret, Didier; Barrière, Nicolas; Boggs, Steven E.; Canipe, Alicia M.; Christensen, Finn E.; Craig, William W.; Forster, Karl; Giommi, Paolo; Grefenstette, Brian W.; Grindlay, Jonathan E.; Harrison, Fiona A.; Hornstrup, Allan; Kitaguchi, Takao; Koglin, Jason E.; Luu, Vy; Madsen, Kristen K.; Mao, Peter H.; Miyasaka, Hiromasa; Perri, Matteo; Pivovaroff, Michael J.; Puccetti, Simonetta; Rana, Vikram; Stern, Daniel; Westergaard, Niels J.; Zhang, William W.; Zoglauer, Andreas

    2015-12-01

    We present the first sub-arcminute images of the Galactic Center above 10 keV, obtained with NuSTAR. NuSTAR resolves the hard X-ray source IGR J17456-2901 into non-thermal X-ray filaments, molecular clouds, point sources, and a previously unknown central component of hard X-ray emission (CHXE). NuSTAR detects four non-thermal X-ray filaments, extending the detection of their power-law spectra with Γ ˜ 1.3-2.3 up to ˜50 keV. A morphological and spectral study of the filaments suggests that their origin may be heterogeneous, where previous studies suggested a common origin in young pulsar wind nebulae (PWNe). NuSTAR detects non-thermal X-ray continuum emission spatially correlated with the 6.4 keV Fe Kα fluorescence line emission associated with two Sgr A molecular clouds: MC1 and the Bridge. Broadband X-ray spectral analysis with a Monte-Carlo based X-ray reflection model self-consistently determined their intrinsic column density (˜1023 cm-2), primary X-ray spectra (power-laws with Γ ˜ 2) and set a lower limit of the X-ray luminosity of Sgr A* flare illuminating the Sgr A clouds to LX ≳ 1038 erg s-1. Above ˜20 keV, hard X-ray emission in the central 10 pc region around Sgr A* consists of the candidate PWN G359.95-0.04 and the CHXE, possibly resulting from an unresolved population of massive CVs with white dwarf masses MWD ˜ 0.9 M⊙. Spectral energy distribution analysis suggests that G359.95-0.04 is likely the hard X-ray counterpart of the ultra-high gamma-ray source HESS J1745-290, strongly favoring a leptonic origin of the GC TeV emission.

  14. A bayesian approach to estimate the size and structure of the broad-line region in active galactic nuclei using reverberation mapping data

    SciTech Connect

    Li, Yan-Rong; Wang, Jian-Min; Du, Pu; Ho, Luis C.; Bai, Jin-Ming

    2013-12-20

    This is the first paper in a series devoted to the systematic study of the size and structure of the broad-line region (BLR) in active galactic nuclei (AGNs) using reverberation mapping (RM) data. We employ a recently developed Bayesian approach that statistically describes the variability as a damped random walk process and delineates the BLR structure using a flexible disk geometry that can account for a variety of shapes, including disks, rings, shells, and spheres. We allow for the possibility that the line emission may respond non-linearly to the continuum, and we detrend the light curves when there is clear evidence for secular variation. We use a Markov Chain Monte Carlo implementation based on Bayesian statistics to recover the parameters and uncertainties for the BLR model. The corresponding transfer function is obtained self-consistently. We tentatively constrain the virial factor used to estimate black hole masses; more accurate determinations will have to await velocity-resolved RM data. Application of our method to RM data with Hβ monitoring for about 40 objects shows that the assumed BLR geometry can reproduce quite well the observed emission-line fluxes from the continuum light curves. We find that the Hβ BLR sizes obtained from our method are on average ∼20% larger than those derived from the traditional cross-correlation method. Nevertheless, we still find a tight BLR size-luminosity relation with a slope of α = 0.55 ± 0.03 and an intrinsic scatter of ∼0.18 dex. In particular, we demonstrate that our approach yields appropriate BLR sizes for some objects (such as Mrk 142 and PG 2130+099) where traditional methods previously encountered difficulties.

  15. Promyelocytic leukemia nuclear bodies associate with transcriptionally active genomic regions

    PubMed Central

    Wang, Jayson; Shiels, Carol; Sasieni, Peter; Wu, Pei Jun; Islam, Suhail A.; Freemont, Paul S.; Sheer, Denise

    2004-01-01

    The promyelocytic leukemia (PML) protein is aggregated into nuclear bodies that are associated with diverse nuclear processes. Here, we report that the distance between a locus and its nearest PML body correlates with the transcriptional activity and gene density around the locus. Genes on the active X chromosome are more significantly associated with PML bodies than their silenced homologues on the inactive X chromosome. We also found that a histone-encoding gene cluster, which is transcribed only in S-phase, is more strongly associated with PML bodies in S-phase than in G0/G1 phase of the cell cycle. However, visualization of specific RNA transcripts for several genes showed that PML bodies were not themselves sites of transcription for these genes. Furthermore, knock-down of PML bodies by RNA interference did not preferentially change the expression of genes closely associated with PML bodies. We propose that PML bodies form in nuclear compartments of high transcriptional activity, but they do not directly regulate transcription of genes in these compartments. PMID:14970191

  16. On the Dynamical Evolution of H II Regions: An Investigation of the Ionized Component of W4, a Galactic Chimney Candidate. I. Kinematics and Dynamics in the Latitude Range 0° <= b <= 3°

    NASA Astrophysics Data System (ADS)

    Lagrois, Dominic; Joncas, Gilles

    2009-02-01

    Fabry-Perot interferometry was used to obtain an Hα survey of the most emissive part of W4, a giant superbubble/H II region located in the Perseus arm. Presented by Normandeau and colleagues as an H I cavity aiming away from the Galactic plane, the void has been morphologically interpreted as a Galactic chimney candidate in interaction with the Galactic corona. We present the kinematical results of nearly five million Hα spectra obtained in the southern portion of the nebula (0° <= b <= 3°). Many small-scale radial velocity gradients are detected in the embedded ionized component and are attributed to the photoionization of dense, mostly molecular, fragments found either in or at the periphery of the expanding supershell. The mean local standard of rest radial velocity associated with our Hα survey is found at -42.565 ± 5.204 (1σ) km s-1, redshifted by roughly 5 km s-1 from the molecular material found in the vicinity of the large superbubble. Investigation of the Hα line-width measurements has shown W4-south to fall in a transient regime between low velocity dispersions characteristic of small-size Galactic H II regions and supersonic line widths associated with supergiant extragalactic structures. The overall kinematics of W4-south is best explained with the Champagne model for the dynamical evolution of H II regions where at least 10 independent gas flows crisscross the nebula. For the first time, a Champagne flow is seen coming to an end within a nebula, mingling with the surrounding ionized gas. The nature (molecular versus atomic) of the neutral material, prone to erosion, is critical as it leads to much different kinematical interpretations. W4-south appears as a text book example of the last stage in the life of a giant molecular cloud complex.

  17. Comparison of the activity measurements in nuclear medicine services in the Brazilian northeast region.

    PubMed

    de Farias Fragoso, Maria da Conceição; de Albuquerque, Antônio Morais; de Oliveira, Mércia L; de Lima, Fabiana Farias; Barreto, Flávio Chiappetta Paes; de Andrade Lima, Ricardo

    2013-12-01

    The Northeastern Regional Centre for Nuclear Sciences (CRCN-NE), National Nuclear Energy Commission, has organized for the first time in nuclear medicine services (NMSs) in the Brazilian northeast region a comparison of activity measurements for (99m)Tc, (131)I, (67)Ga, (201)Tl and (57)Co. This tool is widely utilized to evaluate not only the accuracy of radionuclide calibrators, but also the competence of NMSs to measure the activity of the radiopharmaceuticals and the performance of the personnel involved in these measurements. The comparison results showed that 90% of the results received from participants are within the ±10% limit established by the Brazilian Norm.

  18. Research on the Second Region of Sino-German 6 cm Polarization Survey of the Galactic Plane and Large-scale Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Xiao, L.

    2011-11-01

    Polarization observation provides a useful tool to study the properties of interstellar medium (ISM). It could directly show the orientation of large-scale magnetic fields, and help us understand the structure of large-scale magnetic field in our Galaxy and the evolution of supernova remnants (SNRs). Moreover, combing with polarization observations at other wavelengths, the Faraday rotation could be applied to study the properties of the thermal electron density, filling factor, regular and random magnetic fields in ISM and SNRs.The previous polarization measurements mostly conducted at low frequencies were significantly influenced by the Faraday effects of ISM, while at 6 cm, they are much less affected and polarized emission from larger distances could be detected. By studying Faraday screens, we could explore the physical parameters of the sources as well as the synchrotron emissivities of the Galaxy. The 6 cm total intensity measurements are the key data to clarify the spectrum behavior of diffused emission or individual objects at high frequencies, and help us understand the distribution of relativistic electrons, the disk-halo interaction and the evolution of late-stage SNRs. In August 2009, the project of 6~cm continuum and polarization survey of Galactic plane had been completed successfully using the 25~m radio telescope at Urumqi. The work presented in this thesis is mainly based on data analysis of the second survey region with 60° ≤ l ≤129° and |b|≤5°. We tried to compensate the missing large-scale structures by extrapolating the WMAP K-band polarization data with the spectral index model and simulation of the rotation measures (RMs). By comparing the maps pre- with post-``calibration'', we studied the extended objects in this region. We analyzed the depolarization structure at the periphery of HII region complex using Faraday screen model, and studied the distribution of fluctuation in the entire survey region using structure functions

  19. INTEGRAL Galactic bulge monitoring program

    NASA Astrophysics Data System (ADS)

    Kuulkers, E.; Kouveliotou, C.; van der Horst, A. J.; Belloni, T.; Chenevez, J.; Ibarra, A.; Munoz-Darias, T.; Bazzano, A.; Cadolle Bel, M.; De Cesare, G.; Diaz Trigo, M.; Jourdain, E.; Lubinski, P.; Natalucci, L.; Ness, J. U.; Parmar, A.; Pollock, A. M. T.; Rodriguez, J.; Roques, J. P.; Sanchez-Fernandez; C.; Ubertini, P.; Winkler, C.

    2010-12-01

    The central region of our Galaxy, the Galactic bulge, is a rich host of variable high-energy X-ray and gamma-ray point sources. These sources include bright and relatively faint X-ray transients, X-ray bursters, persistent neutron star and black-hole candidate binaries, high-mass X-ray binaries, etc.. We have a program to monitor the Galactic bulge region regularly and frequently with the gamma-ray observatory INTEGRAL, whenever it is observable. As a service to the scientific community the high-energy light curves of sources present, as well as the images of the region are made available through the WWW at http://integral.esac.esa.int/BULGE/ as soon as possible after the observations have been performed. We show the ongoing results of this exciting program.

  20. NuSTAR HARD X-RAY SURVEY OF THE GALACTIC CENTER REGION. I. HARD X-RAY MORPHOLOGY AND SPECTROSCOPY OF THE DIFFUSE EMISSION

    SciTech Connect

    Mori, Kaya; Hailey, Charles J.; Perez, Kerstin; Nynka, Melania; Zhang, Shuo; Canipe, Alicia M.; Krivonos, Roman; Tomsick, John A.; Barrière, Nicolas; Boggs, Steven E.; Craig, William W.; Hong, Jaesub; Ponti, Gabriele; Bauer, Franz; Alexander, David M.; Baganoff, Frederick K.; Barret, Didier; Christensen, Finn E.; Forster, Karl; Giommi, Paolo; and others

    2015-12-01

    We present the first sub-arcminute images of the Galactic Center above 10 keV, obtained with NuSTAR. NuSTAR resolves the hard X-ray source IGR J17456–2901 into non-thermal X-ray filaments, molecular clouds, point sources, and a previously unknown central component of hard X-ray emission (CHXE). NuSTAR detects four non-thermal X-ray filaments, extending the detection of their power-law spectra with Γ ∼ 1.3–2.3 up to ∼50 keV. A morphological and spectral study of the filaments suggests that their origin may be heterogeneous, where previous studies suggested a common origin in young pulsar wind nebulae (PWNe). NuSTAR detects non-thermal X-ray continuum emission spatially correlated with the 6.4 keV Fe Kα fluorescence line emission associated with two Sgr A molecular clouds: MC1 and the Bridge. Broadband X-ray spectral analysis with a Monte-Carlo based X-ray reflection model self-consistently determined their intrinsic column density (∼10{sup 23} cm{sup −2}), primary X-ray spectra (power-laws with Γ ∼ 2) and set a lower limit of the X-ray luminosity of Sgr A* flare illuminating the Sgr A clouds to L{sub X} ≳ 10{sup 38} erg s{sup −1}. Above ∼20 keV, hard X-ray emission in the central 10 pc region around Sgr A* consists of the candidate PWN G359.95–0.04 and the CHXE, possibly resulting from an unresolved population of massive CVs with white dwarf masses M{sub WD} ∼ 0.9 M{sub ⊙}. Spectral energy distribution analysis suggests that G359.95–0.04 is likely the hard X-ray counterpart of the ultra-high gamma-ray source HESS J1745–290, strongly favoring a leptonic origin of the GC TeV emission.

  1. A SYSTEMATIC SEARCH FOR COROTATING INTERACTION REGIONS IN APPARENTLY SINGLE GALACTIC WOLF-RAYET STARS. II. A GLOBAL VIEW OF THE WIND VARIABILITY

    SciTech Connect

    Chene, A.-N.; St-Louis, N. E-mail: stlouis@astro.umontreal.ca

    2011-08-01

    This study is the second part of a survey searching for large-scale spectroscopic variability in apparently single Wolf-Rayet (WR) stars. In a previous paper (Paper I), we described and characterized the spectroscopic variability level of 25 WR stars observable from the northern hemisphere and found 3 new candidates presenting large-scale wind variability, potentially originating from large-scale structures named corotating interaction regions (CIRs). In this second paper, we discuss an additional 39 stars observable from the southern hemisphere. For each star in our sample, we obtained 4-5 high-resolution spectra with a signal-to-noise ratio of {approx}100 and determined its variability level using the approach described in Paper I. In total, 10 new stars are found to show large-scale spectral variability of which 7 present CIR-type changes (WR 8, WR 44, WR55, WR 58, WR 61, WR 63, WR 100). Of the remaining stars, 20 were found to show small-amplitude changes and 9 were found to show no spectral variability as far as can be concluded from the data on hand. Also, we discuss the spectroscopic variability level of all single galactic WR stars that are brighter than v {approx} 12.5, and some WR stars with 12.5 < v {<=} 13.5, i.e., all the stars presented in our two papers and four more stars for which spectra have already been published in the literature. We find that 23/68 stars (33.8%) present large-scale variability, but only 12/54 stars ({approx}22.1%) are potentially of CIR type. Also, we find that 31/68 stars (45.6%) only show small-scale variability, most likely due to clumping in the wind. Finally, no spectral variability is detected based on the data on hand for 14/68 (20.6%) stars. Interestingly, the variability with the highest amplitude also has the widest mean velocity dispersion.

  2. Induced starburst and nuclear activity: Faith, facts, and theory

    NASA Technical Reports Server (NTRS)

    Shlosman, Isaac

    1990-01-01

    The problem of the origin of starburst and nuclear (nonstellar) activity in galaxies is reviewed. A physical understanding of the mechanism(s) that induce both types of activity requires one to address the following issues: (1) what is the source of fuel that powers starbursts and active galactic nuclei; and (2) how is it channeled towards the central regions of host galaxies? As a possible clue, the author examines the role of non-axisymmetric perturbations of galactic disks and analyzes their potential triggers. Global gravitational instabilities in the gas on scales approx. 100 pc appear to be crucial for fueling the active galactic nuclei.

  3. Galactic diffuse gamma rays from galactic plane

    NASA Astrophysics Data System (ADS)

    Tateyama, N.; Nishimura, J.

    2001-08-01

    The dominant part of the diffuse gamma rays from the Galactic plane, with energy greater than 1TeV, has been thought as due to the inverse Compton scattering of the interstellar photons with the high-energy cosmic electrons. In these energy regions, the diffuse gamma-ray observation gives us unique infor-mation on the energy spectrum of the high-energy electrons in the interstellar space, since we cannot observe those electrons directly. This provides us information on the cosmicray source, production mechanism and propagation in the Galaxy. We discuss the implication of our results by comparing with the work of Porter and Protheroe, and also compare with the data observed by the most recent extensive air showers. It is also pointed out that the patchy structure of gammaray distribution will appear at high-energy side, if we observe the distribution with a higher angular resolution of a few arc degrees. This patchy structure will become clear beyond 10TeV of IC gamma rays, where the number of contributing sources of parent decrease and the diffusion distance of the electrons become smaller.

  4. Galactic gamma-ray observations and galactic structure

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.

    1975-01-01

    Recent observations of gamma-rays originating in the galactic disk together with radio observations, support an emerging picture of the overall structure of our galaxy with higher interstellar gas densities and star formation rates in a region which corresponds to that of the inner arms. The emerging picture is one where molecular clouds make up the dominant constituent of the interstellar gas in the inner galaxy and play a key role in accounting for the gamma-rays and phenomena associated with the production of young stars and other population 1 objects. In this picture, cosmic rays are associated with supernovae and are primarily of galactic origin. These newly observed phenomena can be understood as consequences of the density wave theories of spiral structure. Based on these new developments, the suggestion is made that a new galactic population class, Population O, be added to the standard Populations 1 and 2 in order to recognize important differences in dynamics and distribution between diffuse galactic H1 and interstellar molecular clouds.

  5. Development of Nuclear Engineering Educational Program at Ibaraki University with Regional Collaboration

    NASA Astrophysics Data System (ADS)

    Matsumura, Kunihito; Kaminaga, Fumito; Kanto, Yasuhiro; Tanaka, Nobuatsu; Saigusa, Mikio; Kikuchi, Kenji; Kurumada, Akira

    The College of Engineering, Ibaraki University is located at the Hitachi city, in the north part of Ibaraki prefecture. Hitachi and Tokai areas are well known as concentration of advanced technology center of nuclear power research organizations. By considering these regional advantages, we developed a new nuclear engineering educational program for students in the Collage of Engineering and The Graduate School of Science and Engineering of Ibaraki University. The program is consisted of the fundamental lectures of nuclear engineering and nuclear engineering experiments. In addition, several observation learning programs by visiting cooperative organizations are also included in the curriculum. In this paper, we report about the progress of the new educational program for nuclear engineering in Ibaraki University.

  6. NGC 4314. II - Hubble Space Telescope I-band surface photometry of the nuclear region

    NASA Technical Reports Server (NTRS)

    Benedict, G. F.; Higdon, J. L.; Jefferys, W. H.; Duncombe, R.; Hemenway, P. D.; Shelus, P. J.; Whipple, A. L.; Nelan, E.; Story, D.; Mcarthur, B.

    1993-01-01

    We present an HST I-band Planetary Camera image of the nuclear region of NGC 4314, an anemic barred galaxy with recent star formation confined to a nuclear ring. These data resolve the nuclear ring into multiple sites of new star formation and resolve associated dust lanes into discrete clouds. Deconvolution results in at least 0.13 arcsec resolution, as demonstrated by the de Vaucouleurs r exp 1/4 law. Contrasted with similar studies of M87 and NGC 7457, we find no photometric evidence for an extreme concentration of stars in the center of NGC 4314. We identify an oval distortion of length 8 arcsec in the nuclear region, using ellipse-fitting routines and the unsharp masked frame. This nuclear bar has newer stars near its ends. We catalog 14 star clusters associated with H II regions in the nuclear ring. As an additional demonstration of the resolution achieved, the integral size distribution of these clusters is described by an exponential relationship which prevails down to 0.14 arcsec.

  7. Relativistic Dark Matter at the Galactic Center

    SciTech Connect

    Amin, Mustafa A.; Wizansky, Tommer; /SLAC

    2007-11-16

    In a large region of the supersymmetry parameter space, the annihilation cross section for neutralino dark matter is strongly dependent on the relative velocity of the incoming particles. We explore the consequences of this velocity dependence in the context of indirect detection of dark matter from the galactic center. We find that the increase in the annihilation cross section at high velocities leads to a flattening of the halo density profile near the galactic center and an enhancement of the annihilation signal.

  8. Erratum: VLA H92α and H115β Recombination Line Observations of the Galactic Center H II Regions: The Sickle (G0.18-0.04) and the Pistol (G0.15-0.05)

    NASA Astrophysics Data System (ADS)

    Lang, Cornelia C. Lang; Goss, W. M.; Wood, D. O. S.

    1997-06-01

    In the paper ``VLA H92α and H115β Recombination Line Observations of the Galactic Center H II Regions: The Sickle (G0.18-0.04) and the Pistol (G0.15-0.05)'' by Cornelia C. Lang, W. M. Goss, and D. O. S. Wood (ApJ, 474, 275 [1997]), an error occurred in Figure 9. Figure 9a was printed twice, and Figure 9b was omitted. The correct version of Figure 9b is presented here.

  9. Gamma ray constraints on the galactic supernova rate

    NASA Technical Reports Server (NTRS)

    Hartmann, D.; The, L.-S.; Clayton, D. D.; Leising, M.; Mathews, G.; Woosley, S. E.

    1992-01-01

    Monte Carlo simulations of the expected gamma-ray signatures of galactic supernovae of all types are performed in order to estimate the significance of the lack of a gamma-ray signal due to supernovae occurring during the last millenium. Using recent estimates of nuclear yields, we determine galactic supernova rates consistent with the historic supernova record and the gamma-ray limits. Another objective of these calculations of galactic supernova histories is their application to surveys of diffuse galactic gamma-ray line emission.

  10. The Structure of Active Galactic Nuclei

    NASA Technical Reports Server (NTRS)

    Kriss, Gerard A.

    1997-01-01

    We are continuing our systematic investigation of the nuclear structure of nearby active galactic nuclei (AGN). Upon completion, our study will characterize hypothetical constructs such as narrow-line clouds, obscuring tori, nuclear gas disks. and central black holes with physical measurements for a complete sample of nearby AGN. The major scientific goals of our program are: (1) the morphology of the NLR; (2) the physical conditions and dynamics of individual clouds in the NLR; (3) the structure and physical conditions of the warm reflecting gas; (4) the structure of the obscuring torus; (5) the population and morphology of nuclear disks/tori in AGN; (6) the physical conditions in nuclear disks; and (7) the masses of central black holes in AGN. We will use the Hubble Space Telescope (HST) to obtain high-resolution images and spatially resolved spectra. Far-UV spectroscopy of emission and absorption in the nuclear regions using HST/FOS and the Hopkins Ultraviolet Telescope (HUT) will help establish physical conditions in the absorbing and emitting gas. By correlating the dynamics and physical conditions of the gas with the morphology revealed through our imaging program, we will be able to examine mechanisms for fueling the central engine and transporting angular momentum. The kinematics of the nuclear gas disks may enable us to measure the mass of the central black hole. Contemporaneous X-ray observations using ASCA will further constrain the ionization structure of any absorbing material. Monitoring of variability in the UV and X-ray absorption will be used to determine the location of the absorbing gas, possibly in the outflowing warm reflecting gas, or the broad-line region, or the atmosphere of the obscuring torus. Supporting ground-based observations in the optical, near-IR, imaging polarimetry, and the radio will complete our picture of the nuclear structures. With a comprehensive survey of these characteristics in a complete sample of nearby AGN, our

  11. The Formation of Galactic Bulges

    NASA Astrophysics Data System (ADS)

    Carollo, C. Marcella; Ferguson, Henry C.; Wyse, Rosemary F. G.

    2000-03-01

    Part I. Introduction: What are galactic bulges?; Part II. The Epoch of Bulge Formation: Origin of bulges; Deep sub-mm surveys: High-z ULIRGs and the formation of spheroids; Ages and metallicities for stars in the galactic bulge; Integrated stellar populations of bulges: First results; HST-NICMOS observations of galactic bulges: Ages and dust; Inside-out bulge formation and the origin of the Hubble sequence; Part III. The Timescales of Bulge Formation: Constraints on the bulge formation timescale from stellar populations; Bulge building with mergers and winds; Role of winds, starbursts, and activity in bulge formation; Dynamical timescales of bulge formation; Part IV. Physical Processes in Bulge Formation: the role of bars for secular bulge formation; Bars and boxy/peanut-shaped bulges: an observational point of view; Boxy- and peanut-shaped bulges; A new class of bulges; The role of secondary bars in bulge formation; Radial transport of molecular gas to the nuclei of spiral galaxies; Dynamical evolution of bulge shapes; Two-component stellar systems: Phase-space constraints; Central NGC 2146 - a firehose-type bending instability?; Bulge formation: the role of the multi-phase ISM; Global evolution of a self-gravitating multi-phase ISM in the central kpc region of galaxies; Part V. Bulge Phenomenology: Bulge-disk decomposition of spiral galaxies in the near-infrared; The triaxial bulge of NGC 1371; The bulge-disk orthogonal decoupling in galaxies: NGC 4698 and NGC 4672; The kinematics and the origin of the ionized gas in NGC 4036; Optically thin thermal plasma in the galactic bulge; X-ray properties of bulges; The host galaxies of radio-loud AGN; The centers of radio-loud early-type galaxies with HST; Central UV spikes in two galactic spheroids; Conference summary: where do we stand?

  12. Photometric distances to young stars in the inner Galactic disk. II. The region towards the open cluster Trumpler 27 at L = 355°

    NASA Astrophysics Data System (ADS)

    Perren, G.; Vázquez, R. A.; Carraro, G.

    2012-12-01

    Context. The spiral structure of the Milky Way inside the solar circle is still poorly known because of the high density of the material that causes strong extinction towards the Galactic center. Aims: We present results of the first extensive and deep color-color diagram (CCD) photometric survey carried out in the field of the open cluster Trumpler 27, an object immersed in a region of extremely high visual absorption in the constellation of Sagittarius not far from the Galaxy center. The survey covers almost a quarter of square degree. Methods: We look for young stars clumps that might plausibly be associated with spiral structure. Wide-field UBVI photometry combined with infrared information allows us to reconstruct the distribution in the reddening and distance of young stars in the field using the CCD and color-magnitude diagrams (CMD). Results: The analysis of our data, combined with extensive spectroscopy taken from the literature, shows that the real entity of Trumpler 27 as an open cluster is far from being firmly stated. In fact, instead of finding a relatively compact group of stars confined to a small distance range, we found that stars associated with Trumpler 27 are, indeed, a superposition of early-type stars seen along the line of sight extending over several kiloparsecs beyond even the center of the Galaxy. We demonstrate that at each distance range it becomes possible to generate a CMD resembling that of an open cluster. This way, our analysis indicates that what was considered an open cluster characterized by a significant age spread is a stellar continuum that reaches its maximum number of stars at approximately 3.5 kpc from the Sun, the distance of the Scutum-Crux arm approximately. After analyzing the way early-type stars distribute with distance, we found that some of these stellar groups may be linked, within the distance errors, with other inner spiral arms of our Galaxy, including the Near 3 kpc arm at approximately 5 kpc from the Sun

  13. Nuclear Hybrid Energy Systems - Regional Studies. West Texas and Northeastern Arizona

    SciTech Connect

    Garcia, Humberto E.; Chen, Jun; Kim, Jong S.; McKellar, Michael G.; Deason, Wesley R.; Vilim, Richard B.; Bragg-Sitton, Shannon M.; Boardman, Richard D.

    2015-04-01

    The primary objective of this study is to conduct a preliminary dynamic analysis of two realistic hybrid energy systems (HES) including a nuclear reactor as the main baseload heat generator (denoted as nuclear HES or nuclear hybrid energy systems [NHES]) and to assess the local (e.g., HES owners) and system (e.g., the electric grid) benefits attainable by the application of NHES in scenarios with multiple commodity production and high penetration of renewable energy. It is performed for regional cases - not generic examples - based on available resources, existing infrastructure, and markets within the selected regions. This study also briefly addresses the computational capabilities developed to conduct such analyses, reviews technical gaps, and suggests some research paths forward.

  14. Proliferation concerns in the Russian closed nuclear weapons complex cities : a study of regional migration behavior.

    SciTech Connect

    Flores, Kristen Lee

    2004-07-01

    The collapse of the Soviet Union in 1991 left the legacy of the USSR weapons complex with an estimated 50 nuclear, chemical, and biological weapons cities containing facilities responsible for research, production, maintenance, and destruction of the weapons stockpile. The Russian Federation acquired ten such previously secret, closed nuclear weapons complex cities. Unfortunately, a lack of government funding to support these facilities resulted in non-payment of salaries to employees and even plant closures, which led to an international fear of weapons material and knowledge proliferation. This dissertation analyzes migration in 33 regions of the Russian Federation, six of which contain the ten closed nuclear weapons complex cities. This study finds that the presence of a closed nuclear city does not significantly influence migration. However, the factors that do influence migration are statistically different in regions containing closed nuclear cities compared to regions without closed nuclear cities. Further, these results show that the net rate of migration has changed across the years since the break up of the Soviet Union, and that the push and pull factors for migration have changed across time. Specifically, personal and residential factors had a significant impact on migration immediately following the collapse of the Soviet Union, but economic infrastructure and societal factors became significant in later years. Two significant policy conclusions are derived from this research. First, higher levels of income are found to increase outmigration from regions, implying that programs designed to prevent migration by increasing incomes for closed city residents may be counter-productive. Second, this study finds that programs designed to increase capital and build infrastructure in the new Russian Federation will be more effective for employing scientists and engineers from the weapons complex, and consequently reduce the potential for emigration of

  15. COS-B observations of the high-energy gamma radiation from the galactic disk

    NASA Technical Reports Server (NTRS)

    1977-01-01

    The COS-B experiment has observed approximately one-fourth of the galactic disk, including the galactic-center region, the galactic anticenter, and the Vela region. A completely automatic analysis of the events recorded during these observations reveals a galactic gamma ray emission from the three regions. In the galactic center and Vela regions, the disk emission distribution was measured. From these data, the existence of a local (less than 1 kpc) and a distant (greater than 3 kpc) emitting region is apparent in the general direction of the inner galaxy.

  16. Star formation in the Galactic Center GMC cores: Sagittarius B2 and the dust ridge

    NASA Technical Reports Server (NTRS)

    Lis, D. C.; Menten, K. M.

    1995-01-01

    The total far-infrared luminosity and the ionizing flux inferred from radio continuum observations of the Galactic center region imply a rate of star formation per unit mass of molecular material comparable to that in the Galactic disk. However, H2O and OH masers commonly found in sites of high-mass star formation are relatively rare in the nuclear disk. Far-infrared studies suggest that the formation rate of stars with masses greater than approximately 20 Solar Mass is reduced in the central region compared to the Galactic disk. Star formation might be suppressed currently in the central region as a result of the different geometry and strength of the magnetic fields there, which arguably might tend to inhibit cloud collapse. High gas pressures implied by observations of the diffuse X-ray emission suggest that giant molecular clouds (GMCs) in the nuclear disk may be held together by external pressure rather than self-gravity. The gravitational collapse leading to the formation of high density cores may thus be suppressed in all but the most massive clouds.

  17. REGIONAL BINNING FOR CONTINUED STORAGE OF SPENT NUCLEAR FUEL AND HIGH-LEVEL WASTES

    SciTech Connect

    W. Lee Poe, Jr

    1998-10-01

    In the Continued Storage Analysis Report (CSAR) (Reference 1), DOE decided to analyze the environmental consequences of continuing to store the commercial spent nuclear fuel (SNF) at 72 commercial nuclear power sites and DOE-owned spent nuclear fuel and high-level waste at five Department of Energy sites by region rather than by individual site. This analysis assumes that three commercial facilities pairs--Salem and Hope Creek, Fitzpatrick and Nine-Mile Point, and Dresden and Moms--share common storage due to their proximity to each other. The five regions selected for this analysis are shown on Figure 1. Regions 1, 2, and 3 are the same as those used by the Nuclear Regulatory Commission in their regulatory oversight of commercial power reactors. NRC Region 4 was subdivided into two regions to more appropriately define the two different climates that exist in NRC Region 4. A single hypothetical site in each region was assumed to store all the SNF and HLW in that region. Such a site does not exist and has no geographic location but is a mathematical construct for analytical purposes. To ensure that the calculated results for the regional analyses reflect appropriate inventory, facility and material degradation, and radionuclide transport, the waste inventories, engineered barriers, and environmental conditions for the hypothetical sites were developed from data for each of the existing sites within the given region. Weighting criteria to account for the amount and types of SNF and HLW at each site were used in the development of the environmental data for the regional site, such that the results of the analyses for the hypothetical site were representative of the sum of the results of each actual site if they had been modeled independently. This report defines the actual site data used in development of this hypothetical site, shows how the individual site data was weighted to develop the regional site, and provides the weighted data used in the CSAR analysis. It is

  18. Active galactic nuclei

    PubMed Central

    Fabian, Andrew C.

    1999-01-01

    Active galactic nuclei are the most powerful, long-lived objects in the Universe. Recent data confirm the theoretical idea that the power source is accretion into a massive black hole. The common occurrence of obscuration and outflows probably means that the contribution of active galactic nuclei to the power density of the Universe has been generally underestimated. PMID:10220363

  19. SAS-2 galactic gamma-ray results. 1: Diffuse emission

    NASA Technical Reports Server (NTRS)

    Thompson, D. J.; Fichtel, C. E.; Hartman, R. C.; Kniffen, D. A.; Bignami, G. F.; Lamb, R. C.; Oegelman, H.; Oezel, M. E.; Tuemer, T.

    1977-01-01

    Continuing analysis of the data from the SAS-2 high energy gamma ray experiment has produced an improved picture of the sky at photon energies above 35 MeV. On a large scale, the diffuse emission from the galactic plane is the dominant feature observed by SAS-2. This galactic plane emission is most intense between galactic longitudes 310 deg and 45 deg, corresponding to a region within 7 kpc of the galactic center. Within the high-intensity region, SAS-2 observes peaks around galactic longitudes 315, 330, 345, 0, and 35 deg. These peaks appear to be correlated with galactic features and components such as molecular hydrogen, atomic hydrogen, magnetic fields, cosmic-ray concentrations, and photon fields.

  20. COS-B observations of the high energy gamma radiation from the galactic disc

    NASA Technical Reports Server (NTRS)

    Paul, J.

    1976-01-01

    During the first months of operation, COS-B has observed galactic high energy gamma rays from the galactic disc. In the galactic center and Vela regions the disc emission distribution was measured. From these data the existence of a local ( 1 kpc) and a distant ( 3 kpc) emitting region is apparent in the general direction of the inner galaxy.

  1. PCR primers for 30 novel gene regions in the nuclear genomes of Lepidoptera

    PubMed Central

    Wahlberg, Niklas; Peña, Carlos; Ahola, Milla; Wheat, Christopher W.; Rota, Jadranka

    2016-01-01

    Abstract We report primer pairs for 30 new gene regions in the nuclear genomes of Lepidoptera that can be amplified using a standard PCR protocol. The new primers were tested across diverse Lepidoptera, including nonditrysians and a wide selection of ditrysians. These new gene regions give a total of 11,043 bp of DNA sequence data and they show similar variability to traditionally used nuclear gene regions in studies of Lepidoptera. We feel that a PCR-based approach still has its place in molecular systematic studies of Lepidoptera, particularly at the intrafamilial level, and our new set of primers now provides a route to generating phylogenomic datasets using traditional methods. PMID:27408580

  2. Multi-Decadal Global Cooling and Unprecedented Ozone Loss Following a Regional Nuclear Conflict

    NASA Astrophysics Data System (ADS)

    Mills, M. J.; Toon, O. B.; Lee-Taylor, J. M.; Robock, A.

    2014-12-01

    We present the first study of the global impacts of a regional nuclear war with an Earth system model including atmospheric chemistry, ocean dynamics, and interactive sea-ice and land models (Mills et al., 2014). A limited, regional nuclear war between India and Pakistan in which each side detonates 50 15-kt weapons could produce about 5 Tg of black carbon. This would self-loft to the stratosphere, where it would spread globally, producing a sudden drop in surface temperatures and intense heating of the stratosphere. Using the Community Earth System Model with the Whole Atmosphere Community Climate Model (CESM1(WACCM)), we calculate an e-folding time of 8.7 years for stratospheric black carbon, compared to 4-6.5 years for previous studies (figure panel a). Our calculations show that global ozone losses of 20-50% over populated areas, levels unprecedented in human history, would accompany the coldest average surface temperatures in the last 1000 years (figure panel c). We calculate summer enhancements in UV indices of 30-80% over Mid-Latitudes, suggesting widespread damage to human health, agriculture, and terrestrial and aquatic ecosystems. Killing frosts would reduce growing seasons by 10-40 days per year for 5 years. Surface temperatures would be reduced for more than 25 years, due to thermal inertia and albedo effects in the ocean and expanded sea ice. The combined cooling and enhanced UV would put significant pressures on global food supplies and could trigger a global nuclear famine. Knowledge of the impacts of 100 small nuclear weapons should motivate the elimination of the more than 17,000 nuclear weapons that exist today. Mills, M. J., O. B. Toon, J. Lee-Taylor, and A. Robock (2014), Multidecadal global cooling and unprecedented ozone loss following a regional nuclear conflict, Earth's Future, 2(4), 161-176, doi:10.1002/2013EF000205.

  3. Planetary nebulae near the Galactic Centre: chemical abundances

    NASA Astrophysics Data System (ADS)

    Cavichia, O.; Costa, R. D. D.; Maciel, W. J.; Mollá, M.

    2014-10-01

    In this work, we report physical parameters and abundances derived for a sample of high extinction planetary nebulae located in the Galactic bulge, near the Galactic Centre, based on low dispersion spectroscopy secured at the SOAR telescope using the Goodman spectrograph. The results show that the abundances of our sample are similar to those from other regions of the bulge. Nevertheless, the average abundances of the Galactic bulge do not follow the observed trend of the radial abundance gradient in the disk.

  4. Fe K LINE COMPLEX IN THE NUCLEAR REGION OF NGC 253

    SciTech Connect

    Mitsuishi, Ikuyuki; Yamasaki, Noriko Y.; Takei, Yoh

    2011-12-15

    A bright, nearby edge-on starburst galaxy, NGC 253, was studied using the Suzaku, XMM, and Chandra X-ray observatories. With Suzaku and XMM we detected complex line structure of Fe K, which is resolved into three lines (Fe I at 6.4 keV, Fe XXV at 6.7 keV, and Fe XXVI at 7.0 keV) around the center of NGC 253. Especially, the Fe I and Fe XXVI lines are the first clear detections, with a significance of >99.99% and 99.89% estimated by a Monte Carlo procedure. Imaging spectroscopy with Chandra revealed that the emission is distributed in {approx}60 arcsec{sup 2} region around the nucleus, which suggests that the source is not only the buried active galactic nucleus. The flux of highly ionized Fe lines can be explained by the accumulation of 10-1000 supernova remnants that are the result of high star-forming activity, while the Fe I line flux is consistent with the fluorescent line emission expected with the molecular clouds in the region.

  5. Regional Seismic Discrimination Optimization With and Without Nuclear Test Data: Western U.S. Examples

    SciTech Connect

    Walter, W R; Mayeda, K; Gok, R; Rodgers, A J; Sicherman, A; Hickling, T; Dodge, D; Matzel, E; Ganzberger, M; Parker, V

    2005-06-30

    The western U.S. has abundant natural seismicity, historic nuclear explosion data, and widespread mine blasts, making it a good testing ground to study the performance of regional source-type discrimination techniques. We have assembled and measured a large set of these events to systematically explore how to best optimize discrimination performance. Nuclear explosions can be discriminated from a background of earthquakes using regional phase (Pn, Pg, Sn, Lg) amplitude measures such as high frequency P/S ratios. The discrimination performance is improved if the amplitudes can be corrected for source size and path length effects. We show good results are achieved using earthquakes alone to calibrate for these effects with the MDAC technique (Walter and Taylor, 2001). We show significant further improvement is then possible by combining multiple MDAC amplitude ratios using an optimized weighting technique such as Linear Discriminant Analysis (LDA). However this requires data or models for both earthquakes and explosions. In many areas of the world regional distance nuclear explosion data is lacking, but mine blast data is available. Mine explosions are often designed to fracture and/or move rock, giving them different frequency and amplitude behavior than contained chemical shots, which seismically look like nuclear tests. Here we explore discrimination performance differences between explosion types, the possible disparity in the optimization parameters that would be chosen if only chemical explosions were available and the corresponding effect of that disparity on nuclear explosion discrimination. There are a variety of additional techniques in the literature also having the potential to improve regional high frequency P/S discrimination. We explore two of these here: three-component averaging and maximum phase amplitude measures. Typical discrimination studies use only the vertical component measures and for some historic regional nuclear records these are all

  6. Densities of Galactic Center Clouds

    NASA Astrophysics Data System (ADS)

    Barnes, Jonathan; Mills, Elisabeth A. C.; Morris, Mark R.

    2015-04-01

    The central 300 parsecs of the Galaxy is full of giant molecular clouds containing 107 solar masses worth of gas. However, our Galactic center is not forming as many stars as we think it can, based on the amount of molecular gas in this region. By studying the densities of the Galactic center clouds we hope to better understand why there is not much star formation occurring. Using data from the Green Bank and MOPRA telescopes we have observed multiple rotation transitions of HC3N and its 13C isotopologues. By measuring the integrated intensity of the HC3 N we are able to calculate the densities of these giant molecular clouds. The measured intensities are used with a radiative transfer code called RADEX, to determine volume densities. Our initial results suggest that there may be either less dense or cooler gas in these clouds that previously thought. If there is a significant quantity of gas less dense than 104 molecules/cm3 , this could explain the lack of ongoing star formation in these clouds, and might also suggest a shorter timescale for dynamical disruption of theses clouds. In the future, we plan to improve these results by observing additional HC3N transitions, allowing us better to constrain the relative contributions of multiple temperature and density components in Galactic center clouds.

  7. Relativity and the Galactic-center stars

    NASA Astrophysics Data System (ADS)

    Saha, Prasenjit; Angélil, R.

    2011-05-01

    Galactic-center stars such as S2 reach speeds of a few percent of light at closest approach to the black hole. Hence relativistic effects are potentially observable. The redshift of a star during pericenter passage is especially sensitive to relativity. The same applies to pulsar timing, if a pulsar in that region is discovered. In this work we explain how the equivalence principle, space curvature and frame dragging in principle reveal themselves through the redshift, and discuss possible strategies for disentangling these from the Newtonian perturbations of other mass in the Galactic-center region.

  8. Telomere-surrounding regions are transcription-permissive 3D nuclear compartments in human cells

    SciTech Connect

    Quina, Ana Sofia; Parreira, Leonor . E-mail: lparreir@igc.gulbenkian.pt

    2005-07-01

    Positioning of genes relative to nuclear heterochromatic compartments is thought to help regulate their transcriptional activity. Given that human subtelomeric regions are rich in highly expressed genes, we asked whether human telomeres are related to transcription-permissive nuclear compartments. To address this question, we investigated in the nuclei of normal human lymphocytes the spatial relations of two constitutively expressed genes (ACTB and RARA) and three nuclear transcripts (ACTB, IL2RA and TCRB) to telomeres and centromeres, as a function of gene activity and transcription levels. We observed that genes and gene transcripts locate close to telomere clusters and away from chromocenters upon activation of transcription. These findings, together with the observation that SC35 domains, which are enriched in pre-mRNA processing factors, are in close proximity to telomeres, indicate that telomere-neighboring regions are permissive to gene expression in human cells. Therefore, the associations of telomeres observed in the interphase nucleus might contribute, as opposed to chromocenters, for the establishment of transcription-permissive 3D nuclear compartments.

  9. Nuclear event time histories and computed site transfer functions for locations in the Los Angeles region

    USGS Publications Warehouse

    Rogers, A.M.; Covington, P.A.; Park, R.B.; Borcherdt, R.D.; Perkins, D.M.

    1980-01-01

    This report presents a collection of Nevada Test Site (NTS) nuclear explosion recordings obtained at sites in the greater Los Angeles, Calif., region. The report includes ground velocity time histories, as well as, derived site transfer functions. These data have been collected as part of a study to evaluate the validity of using low-level ground motions to predict the frequency-dependent response of a site during an earthquake. For this study 19 nuclear events were recorded at 98 separate locations. Some of these sites have recorded more than one of the nuclear explosions, and, consequently, there are a total of 159, three-component station records. The location of all the recording sites are shown in figures 1–5, the station coordinates and abbreviations are given in table 1. The station addresses are listed in table 2, and the nuclear explosions that were recorded are listed in table 3. The recording sites were chosen on the basis of three criteria: (1) that the underlying geological conditions were representative of conditions over significant areas of the region, (2) that the site was the location of a strong-motion recording of the 1971 San Fernando earthquake, or (3) that more complete geographical coverage was required in that location.

  10. Nuclear ribosomal internal transcribed spacer (ITS) region as a universal DNA barcode marker for Fungi

    PubMed Central

    Schoch, Conrad L.; Seifert, Keith A.; Huhndorf, Sabine; Robert, Vincent; Spouge, John L.; Levesque, C. André; Chen, Wen; Bolchacova, Elena; Voigt, Kerstin; Crous, Pedro W.; Miller, Andrew N.; Wingfield, Michael J.; Aime, M. Catherine; An, Kwang-Deuk; Bai, Feng-Yan; Barreto, Robert W.; Begerow, Dominik; Bergeron, Marie-Josée; Blackwell, Meredith; Boekhout, Teun; Bogale, Mesfin; Boonyuen, Nattawut; Burgaz, Ana R.; Buyck, Bart; Cai, Lei; Cai, Qing; Cardinali, G.; Chaverri, Priscila; Coppins, Brian J.; Crespo, Ana; Cubas, Paloma; Cummings, Craig; Damm, Ulrike; de Beer, Z. Wilhelm; de Hoog, G. Sybren; Del-Prado, Ruth; Dentinger, Bryn; Diéguez-Uribeondo, Javier; Divakar, Pradeep K.; Douglas, Brian; Dueñas, Margarita; Duong, Tuan A.; Eberhardt, Ursula; Edwards, Joan E.; Elshahed, Mostafa S.; Fliegerova, Katerina; Furtado, Manohar; García, Miguel A.; Ge, Zai-Wei; Griffith, Gareth W.; Griffiths, K.; Groenewald, Johannes Z.; Groenewald, Marizeth; Grube, Martin; Gryzenhout, Marieka; Guo, Liang-Dong; Hagen, Ferry; Hambleton, Sarah; Hamelin, Richard C.; Hansen, Karen; Harrold, Paul; Heller, Gregory; Herrera, Cesar; Hirayama, Kazuyuki; Hirooka, Yuuri; Ho, Hsiao-Man; Hoffmann, Kerstin; Hofstetter, Valérie; Högnabba, Filip; Hollingsworth, Peter M.; Hong, Seung-Beom; Hosaka, Kentaro; Houbraken, Jos; Hughes, Karen; Huhtinen, Seppo; Hyde, Kevin D.; James, Timothy; Johnson, Eric M.; Johnson, Joan E.; Johnston, Peter R.; Jones, E.B. Gareth; Kelly, Laura J.; Kirk, Paul M.; Knapp, Dániel G.; Kõljalg, Urmas; Kovács, Gábor M.; Kurtzman, Cletus P.; Landvik, Sara; Leavitt, Steven D.; Liggenstoffer, Audra S.; Liimatainen, Kare; Lombard, Lorenzo; Luangsa-ard, J. Jennifer; Lumbsch, H. Thorsten; Maganti, Harinad; Maharachchikumbura, Sajeewa S. N.; Martin, María P.; May, Tom W.; McTaggart, Alistair R.; Methven, Andrew S.; Meyer, Wieland; Moncalvo, Jean-Marc; Mongkolsamrit, Suchada; Nagy, László G.; Nilsson, R. Henrik; Niskanen, Tuula; Nyilasi, Ildikó; Okada, Gen; Okane, Izumi; Olariaga, Ibai; Otte, Jürgen; Papp, Tamás; Park, Duckchul; Petkovits, Tamás; Pino-Bodas, Raquel; Quaedvlieg, William; Raja, Huzefa A.; Redecker, Dirk; Rintoul, Tara L.; Ruibal, Constantino; Sarmiento-Ramírez, Jullie M.; Schmitt, Imke; Schüßler, Arthur; Shearer, Carol; Sotome, Kozue; Stefani, Franck O.P.; Stenroos, Soili; Stielow, Benjamin; Stockinger, Herbert; Suetrong, Satinee; Suh, Sung-Oui; Sung, Gi-Ho; Suzuki, Motofumi; Tanaka, Kazuaki; Tedersoo, Leho; Telleria, M. Teresa; Tretter, Eric; Untereiner, Wendy A.; Urbina, Hector; Vágvölgyi, Csaba; Vialle, Agathe; Vu, Thuy Duong; Walther, Grit; Wang, Qi-Ming; Wang, Yan; Weir, Bevan S.; Weiß, Michael; White, Merlin M.; Xu, Jianping; Yahr, Rebecca; Yang, Zhu L.; Yurkov, Andrey; Zamora, Juan-Carlos; Zhang, Ning; Zhuang, Wen-Ying; Schindel, David

    2012-01-01

    Six DNA regions were evaluated as potential DNA barcodes for Fungi, the second largest kingdom of eukaryotic life, by a multinational, multilaboratory consortium. The region of the mitochondrial cytochrome c oxidase subunit 1 used as the animal barcode was excluded as a potential marker, because it is difficult to amplify in fungi, often includes large introns, and can be insufficiently variable. Three subunits from the nuclear ribosomal RNA cistron were compared together with regions of three representative protein-coding genes (largest subunit of RNA polymerase II, second largest subunit of RNA polymerase II, and minichromosome maintenance protein). Although the protein-coding gene regions often had a higher percent of correct identification compared with ribosomal markers, low PCR amplification and sequencing success eliminated them as candidates for a universal fungal barcode. Among the regions of the ribosomal cistron, the internal transcribed spacer (ITS) region has the highest probability of successful identification for the broadest range of fungi, with the most clearly defined barcode gap between inter- and intraspecific variation. The nuclear ribosomal large subunit, a popular phylogenetic marker in certain groups, had superior species resolution in some taxonomic groups, such as the early diverging lineages and the ascomycete yeasts, but was otherwise slightly inferior to the ITS. The nuclear ribosomal small subunit has poor species-level resolution in fungi. ITS will be formally proposed for adoption as the primary fungal barcode marker to the Consortium for the Barcode of Life, with the possibility that supplementary barcodes may be developed for particular narrowly circumscribed taxonomic groups. PMID:22454494

  11. Fermi Galactic Center Zoom

    NASA Video Gallery

    This animation zooms into an image of the Milky Way, shown in visible light, and superimposes a gamma-ray map of the galactic center from NASA's Fermi. Raw data transitions to a view with all known...

  12. Analysis of sheltering and evacuation strategies for a national capital region nuclear detonation scenario.

    SciTech Connect

    Yoshimura, Ann S.; Brandt, Larry D.

    2011-12-01

    Development of an effective strategy for shelter and evacuation is among the most important planning tasks in preparation for response to a low yield, nuclear detonation in an urban area. Extensive studies have been performed and guidance published that highlight the key principles for saving lives following such an event. However, region-specific data are important in the planning process as well. This study examines some of the unique regional factors that impact planning for a 10 kT detonation in the National Capital Region. The work utilizes a single scenario to examine regional impacts as well as the shelter-evacuate decision alternatives at one exemplary point. For most Washington, DC neighborhoods, the excellent assessed shelter quality available make shelter-in-place or selective transit to a nearby shelter a compelling post-detonation strategy.

  13. Galactic cosmic ray composition

    NASA Technical Reports Server (NTRS)

    Meyer, J. P.

    1986-01-01

    An assessment is given of the galactic cosmic ray source (GCRS) elemental composition and its correlation with first ionization potential. The isotopic composition of heavy nuclei; spallation cross sections; energy spectra of primary nuclei; electrons; positrons; local galactic reference abundances; comparison of solar energetic particles and solar coronal compositions; the hydrogen; lead; nitrogen; helium; and germanium deficiency problems; and the excess of elements are among the topics covered.

  14. Einstein observations of the galactic centre

    NASA Technical Reports Server (NTRS)

    Watson, M. G.; Willingale, R.; Hertz, P.; Grindlay, J. E.

    1981-01-01

    A description is presented of the X-ray observations made with the Einstein Observatory Imaging Proportional Counter of a 1 x 1 degree field centered near the galactic nucleus. In the direction of the galactic center the interstellar medium is generally opaque to all radiation between the visual and extreme ultraviolet due to the large column density of the intervening gas and dust. The importance of this X-ray study lies in the fact that it opens up a new window in which the central regions of the Milky Way Galaxy can be observed. The X-ray image is clearly dominated by a bright, central region of emission elongated along the galactic plane. Also presented are a number of unresolved sources.

  15. In silico and wet-bench identification of nuclear matrix attachment regions.

    PubMed

    Krawetz, Stephen A; Draghici, Sorin; Goodrich, Robert; Liu, Zhandong; Ostermeier, G Charles

    2005-01-01

    Chromatin loops are tethered at discrete regions that are approx 100-1000 bp in length. These regions of attachment serve as specific sequence landmarks, anchoring the DNA to the fibers of the chromosomal scaffold. It has been estimated that our genome contains 70,000 nuclear matrix attachment sites that serve as a dynamic nuclear organizer in both the interphase and metaphase cell. Approximately 30,000-40,000 matrix attachment regions (MARs) serve as origins of replication. MARs can also be associated with chromosomal segments densely populated with transcription factor-binding sites. This may facilitate transcription that is initiated within the region of the chromosome coincident with the surface of the nuclear matrix. Assuming an average somatic loop size of 100 kb, it is reasonable to propose that each cell utilizes 30,000 MARs to anchor each of the approx 20,000 active genic domains. This is sufficient to encompass the 30,000 functional genes in our genome that exist as members of single or multigenic families, each constituting a single chromatin domain. With the sequencing phase of various genome projects complete, in silico tools are being developed to identify the long-range control elements that modulate gene expression. This information is necessary to specifically target the time-intensive wet-bench verification and expression experiments that will provide a unified understanding of gene regulation. In this chapter we review some of the in silico strategies that are currently available and a new in vivo method based on the real-time polymerase chain reaction, to assess regions of matrix association.

  16. Multidecadal global cooling and unprecedented ozone loss following a regional nuclear conflict

    NASA Astrophysics Data System (ADS)

    Mills, Michael J.; Toon, Owen B.; Lee-Taylor, Julia; Robock, Alan

    2014-04-01

    We present the first study of the global impacts of a regional nuclear war with an Earth system model including atmospheric chemistry, ocean dynamics, and interactive sea ice and land components. A limited, regional nuclear war between India and Pakistan in which each side detonates 50 15 kt weapons could produce about 5 Tg of black carbon (BC). This would self-loft to the stratosphere, where it would spread globally, producing a sudden drop in surface temperatures and intense heating of the stratosphere. Using the Community Earth System Model with the Whole Atmosphere Community Climate Model, we calculate an e-folding time of 8.7 years for stratospheric BC compared to 4-6.5 years for previous studies. Our calculations show that global ozone losses of 20%-50% over populated areas, levels unprecedented in human history, would accompany the coldest average surface temperatures in the last 1000 years. We calculate summer enhancements in UV indices of 30%-80% over midlatitudes, suggesting widespread damage to human health, agriculture, and terrestrial and aquatic ecosystems. Killing frosts would reduce growing seasons by 10-40 days per year for 5 years. Surface temperatures would be reduced for more than 25 years due to thermal inertia and albedo effects in the ocean and expanded sea ice. The combined cooling and enhanced UV would put significant pressures on global food supplies and could trigger a global nuclear famine. Knowledge of the impacts of 100 small nuclear weapons should motivate the elimination of more than 17,000 nuclear weapons that exist today.

  17. Star formation in Galactic flows

    NASA Astrophysics Data System (ADS)

    Smilgys, Romas; Bonnell, Ian A.

    2016-06-01

    We investigate the triggering of star formation in clouds that form in Galactic scale flows as the interstellar medium passes through spiral shocks. We use the Lagrangian nature of smoothed particle hydrodynamics simulations to trace how the star-forming gas is gathered into self-gravitating cores that collapse to form stars. Large-scale flows that arise due to Galactic dynamics create shocks of the order of 30 km s-1 that compress the gas and form dense clouds (n > several × 102 cm-3) in which self-gravity becomes relevant. These large-scale flows are necessary for creating the dense physical conditions for gravitational collapse and star formation. Local gravitational collapse requires densities in excess of n > 103 cm-3 which occur on size scales of ≈1 pc for low-mass star-forming regions (M < 100 M⊙), and up to sizes approaching 10 pc for higher mass regions (M > 103 M⊙). Star formation in the 250 pc region lasts throughout the 5 Myr time-scale of the simulation with a star formation rate of ≈10-1 M⊙ yr-1 kpc-2. In the absence of feedback, the efficiency of the star formation per free-fall time varies from our assumed 100 per cent at our sink accretion radius to values of <10-3 at low densities.

  18. The Bolocam Galactic Plane Survey

    NASA Technical Reports Server (NTRS)

    Glenn, Jason; Aguirre, James; Bally, John; Battersby, Cara; Bradley, Eric Todd; Cyganowski, Claudia; Dowell, Darren; Drosback, Meredith; Dunham, Miranda K.; Evans, Neal J., II; Ginsburg, Adam; Harvey, Paul; Rosolowsky, Erik; Schlingman, Wayne; Shirley, Yancy L.; Stringfellow, Guy S.; Walawender, Josh; Williams, Jonathan

    2009-01-01

    The Bolocam Galactic Plane Survey (BGPS) is a 1.1 millimeter continuum survey of the northern Galactic Plane made with Bolocam and the Caltech Submillimeter Observatory. The coverage totals 170 square degrees, comprised of a contiguous range from -10.5 deg is less than or equal to 90.5 deg, 0.5 deg is less than or equal to b is less than or equal to 0.5 deg, with extended coverage in b in selected regions, and four targeted regions in the outer Galaxy, including: IC1396, toward the Perseus arm at l is approximately 111 deg, W3/4/5, and Gem OB1. Depths of the maps range from 30 to 60 mJy beam (sup 1). Approximately 8,400 sources were detected and the maps and source catalog have been made publicly available. Millimeter-wave thermal dust emission reveals dense regions within molecular clouds, thus the BGPS serves as a database for studies of the dense interstellar medium and star formation within the Milky Way.

  19. Mapping regions in Ste5 that support Msn5-dependent and -independent nuclear export.

    PubMed

    Hu, Zhenhua; Wang, Yunmei; Yu, Lu; Mahanty, Sanjoy K; Mendoza, Natalia; Elion, Elaine A

    2016-04-01

    Careful control of the available pool of the MAPK scaffold Ste5 is important for mating-pathway activation and the prevention of inappropriate mating differentiation in haploid Saccharomyces cerevisiae. Ste5 shuttles constitutively through the nucleus, where it is degraded by a ubiquitin-dependent mechanism triggered by G1 CDK phosphorylation. Here we narrow-down regions of Ste5 that mediate nuclear export. Four regions in Ste5 relocalize SV40-TAgNLS-GFP-GFP from nucleus to cytoplasm. One region is N-terminal, dependent on exportin Msn5/Ste21/Kap142, and interacts with Msn5 in 2 hybrid assays independently of mating pheromone, Fus3, Kss1, Ptc1, the NLS/PM, and RING-H2. A second region overlaps the PH domain and Ste11 binding site and 2 others are on the vWA domain and include residues essential for MAPK activation. We find no evidence for dependence on Crm1/Xpo1, despite numerous potential nuclear export sequences (NESs) detected by LocNES and NetNES1.1 predictors. Thus, Msn5 (homolog of human Exportin-5) and one or more exportins or adaptor molecules besides Crm1/Xpo1 may regulate Ste5 through multiple recognition sites. PMID:26824509

  20. Quark matter as dark matter in modeling galactic halo

    NASA Astrophysics Data System (ADS)

    Rahaman, Farook; Kuhfittig, P. K. F.; Amin, Ruhul; Mandal, Gurudas; Ray, Saibal; Islam, Nasarul

    2012-08-01

    Considering the flat rotation curves as input and treating the matter content in the galactic halo region as quark matter, we have found out a background spacetime metric for the region of the galactic halo. We obtain fairly general conditions that ensure that gravity in the halo region is attractive. We also investigate the stability of circular orbits, along with a different role for quark matter. Bag-model quark matter meeting these conditions therefore provides a suitable model for dark matter.

  1. On the biological hazard of galactic antinuclei

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Townsend, L. W.; Buck, W. W.

    1986-01-01

    The interaction of antinuclei in the galactic cosmic-ray beam with biological systems is studied. A nuclei-antinuclei annihilation event observed in nuclear emulsion near the end of the slowing-down trajectories of singly charged particle is discussed. An annihilation event that occurred by capture of the antinucleus into an atomic orbital followed by cascade to or near the ground atomic state and subsequent annihilation with the nuclear material of the atom is described. Microdosimetric quantities relevant to potential biological hazards are estimated. The average linear-energy-transfer spectrum for galactic cosmic ray antinuclei annihilation events in tissues is presented. It is observed that the annihilation in tissues occurs mainly in O and the heavier elements around K.

  2. Argon and neon in Galactic nebulae

    NASA Technical Reports Server (NTRS)

    Simpson, Janet P.; Bregman, Jesse D.; Dinerstein, H. L.; Lester, Dan F.; Rank, David M.; Witteborn, F. C.; Wooden, D. H.

    1995-01-01

    KAO observations of the 6.98 micron line of (Ar II), and KAO and ground-based observations of the 8.99 micron line of (Ar III) and the 12.8 micron line of (Ne II) are presented for a number of Galactic H II regions and planetary nebulae.

  3. Radionuclide monitoring in molluscs inhabiting intertidal region near a nuclear installation, Gulf of Mannar, India.

    PubMed

    Khan, M Feroz; Wesley, S Godwin

    2012-02-01

    Protection of non-human biota from ionizing contaminants, especially in the vicinity of nuclear installations is a very important aspect for nuclear engineers and ecologists. In this view, a baseline data on the activity concentration of (210)Po and (210)Pb were quantified in different tissues of molluscs inhabiting the intertidal region along the coast of Kudankulam. The activity concentration was noticed higher in the organs associated with digestion and metabolism. Filter feeding bivalve molluscs registered the maximum activity of (210)Po in their whole body compared to grazing gastropods. (210)Po:(210)Pb ratio was calculated to be greater than unity in most of the analysed tissues. The ecological sensitivity of molluscs to the radiation exposure and the safeness of the environment was analysed by calculating the external and internal dose rate. The hazard quotient for molluscs was lesser than the global bench mark dose rate of 10 μGyh(-1).

  4. Mathematical model to predict regions of chromatin attachment to the nuclear matrix.

    PubMed Central

    Singh, G B; Kramer, J A; Krawetz, S A

    1997-01-01

    The potentiation and subsequent initiation of transcription are complex biological phenomena. The region of attachment of the chromatin fiber to the nuclear matrix, known as the matrix attachment region or scaffold attachment region (MAR or SAR), are thought to be requisite for the transcriptional regulation of the eukaryotic genome. As expressed sequences should be contained in these regions, it becomes significant to answer the following question: can these regions be identified from the primary sequence data alone and subsequently used as markers for expressed sequences? This paper represents an effort toward achieving this goal and describes a mathematical model for the detection of MARs. The location of matrix associated regions has been linked to a variety of sequence patterns. Consequently, a list of these patterns is compiled and represented as a set of decision rules using an AND-OR formulation. The DNA sequence was then searched for the presence of these patterns and a statistical significance was associated with the frequency of occurrence of the various patterns. Subsequently, a mathematical potential value,MAR-Potential, was assigned to a sequence region as the inverse proportion to the probability that the observed pattern population occurred at random. Such a MAR detection process was applied to the analysis of a variety of known MAR containing sequences. Regions of matrix association predicted by the software essentially correspond to those determined experimentally. The human T-cell receptor and the DNA sequence from the Drosophila bithorax region were also analyzed. This demonstrates the usefulness of the approach described as a means to direct experimental resources. PMID:9060438

  5. Alimentary tract absorption (f1 values) for radionuclides in local and regional fallout from nuclear tests.

    PubMed

    Ibrahim, Shawki A; Simon, Steven L; Bouville, André; Melo, Dunstana; Beck, Harold L

    2010-08-01

    This paper presents gastrointestinal absorption fractions (f1 values) for estimating internal doses from local and regional fallout radionuclides due to nuclear tests. The choice of f1 values are based on specific circumstances of weapons test conditions and a review of reported f1 values for elements in different physical and chemical states. Special attention is given to fallout from nuclear tests conducted at the Marshall Islands. We make a distinction between the f1 values for intakes of radioactive materials immediately after deposition (acute intakes) and intakes that occur in the course of months and years after deposition, following incorporation into terrestrial and aquatic foodstuffs (chronic intakes). Multiple f1 values for different circumstances where persons are exposed to radioactive fallout (e.g., local vs. regional fallout and coral vs. continental tests) are presented when supportive information is available. In some cases, our selected f1 values are similar to those adopted by the International Commission on Radiological Protection (ICRP) (e.g., iodine and most actinides). However, f1 values for cesium and strontium derived from urine bioassay data of the Marshallese population are notably lower than the generic f1 values recommended by ICRP, particularly for acute intakes from local fallout (0.4 and 0.05 for Cs and Sr, respectively). The f1 values presented here form the first complete set of values relevant to realistic dose assessments for exposure to local or regional radioactive fallout. PMID:20622554

  6. Alimentary Tract Absorption (f1 Values) for Radionuclides in Local and Regional Fallout from Nuclear Tests

    PubMed Central

    Ibrahim, Shawki; Simon, Steven L; Bouville, André; Melo, Dunstana; Beck, Harold

    2009-01-01

    This paper presents gastrointestinal absorption fractions (f1 values) for estimating internal doses from local and regional fallout radionuclides due to nuclear tests. The choice of f1 values are based on specific circumstances of weapons test conditions and a review of reported f1 values for elements in different physical and chemical states. Special attention is given to fallout from nuclear tests conducted at the Marshall Islands. We make a distinction between the f1 values for intakes of radioactive materials immediately after deposition (acute intakes) and intakes that occur in the course of months and years after deposition, following incorporation into terrestrial and aquatic foodstuffs (chronic intakes). Multiple f1 values for different circumstances where persons are exposed to radioactive fallout (e.g. local vs. regional fallout and coral vs. continental tests) are presented when supportive information is available. In some cases, our selected f1 values are similar to those adopted by the ICRP (e.g. iodine and most actinides). However, f1 values for cesium and strontium derived from urine bioassay data of the Marshallese population are notably lower than the generic f1 values recommended by ICRP, particularly for acute intakes from local fallout (0.4 and 0.05 for Cs and Sr, respectively. The f1 values presented here form the first complete set of values relevant to realistic dose assessments for exposure to local or regional radioactive fallout. PMID:20622554

  7. Alimentary tract absorption (f1 values) for radionuclides in local and regional fallout from nuclear tests.

    PubMed

    Ibrahim, Shawki A; Simon, Steven L; Bouville, André; Melo, Dunstana; Beck, Harold L

    2010-08-01

    This paper presents gastrointestinal absorption fractions (f1 values) for estimating internal doses from local and regional fallout radionuclides due to nuclear tests. The choice of f1 values are based on specific circumstances of weapons test conditions and a review of reported f1 values for elements in different physical and chemical states. Special attention is given to fallout from nuclear tests conducted at the Marshall Islands. We make a distinction between the f1 values for intakes of radioactive materials immediately after deposition (acute intakes) and intakes that occur in the course of months and years after deposition, following incorporation into terrestrial and aquatic foodstuffs (chronic intakes). Multiple f1 values for different circumstances where persons are exposed to radioactive fallout (e.g., local vs. regional fallout and coral vs. continental tests) are presented when supportive information is available. In some cases, our selected f1 values are similar to those adopted by the International Commission on Radiological Protection (ICRP) (e.g., iodine and most actinides). However, f1 values for cesium and strontium derived from urine bioassay data of the Marshallese population are notably lower than the generic f1 values recommended by ICRP, particularly for acute intakes from local fallout (0.4 and 0.05 for Cs and Sr, respectively). The f1 values presented here form the first complete set of values relevant to realistic dose assessments for exposure to local or regional radioactive fallout.

  8. Identification of a region within the ubiquitin-activating enzyme required for nuclear targeting and phosphorylation.

    PubMed

    Stephen, A G; Trausch-Azar, J S; Handley-Gearhart, P M; Ciechanover, A; Schwartz, A L

    1997-04-18

    The ubiquitin-activating enzyme exists as two isoforms: E1a, localized predominantly in the nucleus, and E1b, localized in the cytoplasm. Previously we generated hemagglutinin (HA) epitope-tagged cDNA constructs, HA1-E1 (epitope tag placed after the first methionine) and HA2-E1 (epitope tag placed after the second methionine) (Handley-Gearhart, P. M., Stephen, A. G., Trausch-Azar, J. S., Ciechanover, A., and Schwartz, A. L. (1994) J. Biol. Chem. 269, 33171-33178), which represent the native isoforms. HA1-E1 is exclusively nuclear, whereas HA2-E1 is found predominantly in the cytoplasm. Using high resolution isoelectric focusing and SDS-polyacrylamide gel electrophoresis, we confirm that these epitope-tagged constructs HA1-E1 and HA2-E1 represent the two isoforms E1a and E1b. HA1-E1/E1a exists as one non-phosphorylated and four phosphorylated forms, and HA2-E1/E1b exists as one predominant non-phosphorylated form and two minor phosphorylated forms. We demonstrate that the first 11 amino acids are essential for phosphorylation and exclusive nuclear localization of HA1-E1. Within this region are four serine residues and a putative nuclear localization sequence (NLS; 5PLSKKRR). Removal of these four serine residues reduced phosphorylation levels by 60% but had no effect on nuclear localization of HA1-E1. Each serine residue was independently mutated to an alanine and analyzed by two-dimensional electrophoresis; only serine 4 was phosphorylated. Disruption of the basic amino acids within the NLS resulted in loss of exclusive nuclear localization and a 90-95% decrease in the phosphorylation of HA1-E1. This putative NLS was able to confer nuclear import on a non-nuclear protein in digitonin-permeabilized cells in a temperature- and ATP-dependent manner. Thus the predominant requirement for efficient phosphorylation of HA1-E1/E1a is a functional NLS, suggesting that E1a may be phosphorylated within the nucleus. PMID:9099746

  9. VERITAS Galactic Observations

    NASA Astrophysics Data System (ADS)

    Hughes, Gareth

    2013-06-01

    We report on recent Galactic results and discoveries made by the VERITAS collaboration. The Very Energetic Radiation Imaging Telescope Array System (VERITAS) is a ground-based gamma-ray observatory, located in southern Arizona, able to detect gamma rays of energies from 100 GeV up to 30 TeV. VERITAS has been fully operational since 2007 and its current sensitivity enables the detection of a 1% Crab Nebula flux at 5 sigma in under 30 hours. The observatory is well placed to view large parts of the galactic plane including its center, resulting in a strong galactic program. Objects routinely observed include Pulsars, Pulsar Wind Nebula, X-ray binaries and sources with unidentified counterparts in other wavelengths.

  10. The diffuse galactic far-ultraviolet sky

    SciTech Connect

    Hamden, Erika T.; Schiminovich, David; Seibert, Mark

    2013-12-20

    We present an all-sky map of the diffuse Galactic far ultraviolet (1344-1786 Å) background using Galaxy Evolution Explorer data, covering 65% of the sky with 11.79 arcmin{sup 2} pixels. We investigate the dependence of the background on Galactic coordinates, finding that a standard cosecant model of intensity is not a valid fit. Furthermore, we compare our map to Galactic all-sky maps of 100 μm emission, N {sub H} {sub I} column, and Hα intensity. We measure a consistent low level far-UV (FUV) intensity at zero points for other Galactic quantities, indicating a 300 photons cm{sup –2} s{sup –1} sr{sup –1} Å{sup –1} non-scattered isotropic component to the diffuse FUV. There is also a linear relationship between FUV and 100 μm emission below 100 μm values of 8 MJy sr{sup –1}. We find a similar linear relationship between FUV and N {sub H} {sub I} below 10{sup 21} cm{sup –2}. The relationship between FUV and Hα intensity has no such constant cutoff. For all Galactic quantities, the slope of the linear portion of the relationship decreases with Galactic latitude. A modified cosecant model, taking into account dust scattering asymmetry and albedo, is able to accurately fit the diffuse FUV at latitudes above 20°. The best fit model indicates an albedo, a, of 0.62 ± 0.04 and a scattering asymmetry function, g, of 0.78 ± 0.05. Deviations from the model fit may indicate regions of excess FUV emission from fluorescence or shock fronts, while low latitude regions with depressed FUV emission are likely the result of self-shielding dusty clouds.

  11. Where Galactic Snakes Live

    NASA Technical Reports Server (NTRS)

    2006-01-01

    This infrared image from NASA's Spitzer Space Telescope shows what astronomers are referring to as a 'snake' (upper left) and its surrounding stormy environment. The sinuous object is actually the core of a thick, sooty cloud large enough to swallow dozens of solar systems. In fact, astronomers say the 'snake's belly' may be harboring beastly stars in the process of forming.

    The galactic creepy crawler to the right of the snake is another thick cloud core, in which additional burgeoning massive stars might be lurking. The colorful regions below the two cloud cores are less dense cloud material, in which dust has been heated by starlight and glows with infrared light. Yellow and orange dots throughout the image are monstrous developing stars; the red star on the 'belly' of the snake is 20 to 50 times as massive as our sun. The blue dots are foreground stars.

    The red ball at the bottom left is a 'supernova remnant,' the remains of massive star that died in a fiery blast. Astronomers speculate that radiation and winds from the star before it died, in addition to a shock wave created when it exploded, might have played a role in creating the snake.

    Spitzer was able to spot the two black cloud cores using its heat-seeking infrared vision. The objects are hiding in the dusty plane of our Milky Way galaxy, invisible to optical telescopes. Because their heat, or infrared light, can sneak through the dust, they first showed up in infrared images from past missions. The cloud cores are so thick with dust that if you were to somehow transport yourself into the middle of them, you would see nothing but black, not even a star in the sky. Now, that's spooky!

    Spitzer's new view of the region provides the best look yet at the massive embryonic stars hiding inside the snake. Astronomers say these observations will ultimately help them better understand how massive stars form. By studying the clustering and range of masses of the stellar embryos, they hope

  12. Radionuclide radiologist directed nuclear medicine services in district general hospitals in the South Thames Region.

    PubMed

    Conry, B G; Burwood, R J

    2001-08-01

    The equipment, staffing levels and imaging workload of all 14 radiologist directed nuclear medicine services in district general hospitals in the South Thames Region are presented. These are generally single camera departments providing a broad range of imaging procedures, including cardiac studies and white cell labelling, as well as the more usual renal, lung, thyroid and bone examinations. All departments have a high throughput, averaging 2358 examinations per year. Departmental staffing levels are variable, with some institutions having inadequate consultant radiology sessions free of other commitments as well as inadequate physics support. Potentially, these are important quality and legal issues that departments may need to address with hospital Trusts and Commissioning Agencies. Four small departments provided a service without any formally contracted radiologist sessions for nuclear medicine in the radiologists' job plans. The three medium sized departments have a closer match between sessions contracted and those actually worked, but in only one of these did the contracted sessional commitment equal the recommendation of the Nuclear Medicine Committee of the Royal College of Physicians. There is a disparity between the number of contracted consultant sessions and those actually worked in most institutions (86%), being at least two sessions in eight hospitals. Recommendations are made regarding the adequacy of some of the elements of provision in South Thames and the legal and safety implications for hospital Trust management and Commissioning Agencies. PMID:11511496

  13. The Signal Sequence Coding Region Promotes Nuclear Export of mRNA

    PubMed Central

    Palazzo, Alexander F; Springer, Michael; Shibata, Yoko; Lee, Chung-Sheng; Dias, Anusha P; Rapoport, Tom A

    2007-01-01

    In eukaryotic cells, most mRNAs are exported from the nucleus by the transcription export (TREX) complex, which is loaded onto mRNAs after their splicing and capping. We have studied in mammalian cells the nuclear export of mRNAs that code for secretory proteins, which are targeted to the endoplasmic reticulum membrane by hydrophobic signal sequences. The mRNAs were injected into the nucleus or synthesized from injected or transfected DNA, and their export was followed by fluorescent in situ hybridization. We made the surprising observation that the signal sequence coding region (SSCR) can serve as a nuclear export signal of an mRNA that lacks an intron or functional cap. Even the export of an intron-containing natural mRNA was enhanced by its SSCR. Like conventional export, the SSCR-dependent pathway required the factor TAP, but depletion of the TREX components had only moderate effects. The SSCR export signal appears to be characterized in vertebrates by a low content of adenines, as demonstrated by genome-wide sequence analysis and by the inhibitory effect of silent adenine mutations in SSCRs. The discovery of an SSCR-mediated pathway explains the previously noted amino acid bias in signal sequences and suggests a link between nuclear export and membrane targeting of mRNAs. PMID:18052610

  14. Geology of the Chinese nuclear test site near Lop Nor, Xinjiang Uygur Autonomous Region, China

    USGS Publications Warehouse

    Matzko, J.R.

    1994-01-01

    The Chinese underground nuclear test site in the Kuruktag and Kyzyltag mountains of the Xinjiang Uygur Autonomous Region of northwest China, is the location of sixteen underground tests that occurred between 1969 and 1992. The largest test to date, conducted on 21 May 1992, had a reported yield of about one megaton. Geophysical properties of the rocks and a large-scale geologic map of part of the test area were published by the Chinese in 1986 and 1987 and are the first site-specific data available for this test site. In areas of low relief, underground nuclear testing has occurred below the water table, in shafts drilled vertically into dense, low porosity Paleozoic granitic and metasedimentary rocks. Additional testing in areas of more rugged terrain has occurred in horizontal tunnels, probably above the water table. At least one of these tunnels was driven into granite. The upper 50 m of the rock in the area of the vertical tests is weathered and fractured; these conditions have been shown to influence the magnitude of the disturbance of the land surface after a nuclear explosion. These descriptions suggest hard rock coupling at depth and a closer resemblance to the former Soviet test site in eastern Kazakhstan than to the U.S. test site in Nevada. ?? 1994.

  15. Dependence of Enhancer-Mediated Transcription of the Immunoglobulin μ Gene on Nuclear Matrix Attachment Regions

    NASA Astrophysics Data System (ADS)

    Forrester, William C.; van Genderen, Courtney; Jenuwein, Thomas; Grosschedl, Rudolf

    1994-08-01

    Transcription of the immunoglobulin μ heavy chain locus is regulated by an intronic enhancer that is flanked on both sides by nuclear matrix attachment regions (MARs). These MARs have now been shown to be essential for transcription of a rearranged μ gene in transgenic B lymphocytes, but they were not required in stably transfected tissue culture cells. Normal rates of transcriptional initiation at a variable region promoter and the formation of an extended deoxyribonuclease I (DNase I)-sensitive chromatin domain were dependent on MARs, although DNase I hypersensitivity at the enhancer was detected in the absence of MARs. Thus, transcriptional activation of the μ gene during normal lymphoid development requires a synergistic collaboration between the enhancer and flanking MARs.

  16. Structure of the disturbed region of the atmosphere after the nuclear explosion in Hiroshima

    NASA Astrophysics Data System (ADS)

    Shcherbin, M. D.; Pavlyukov, K. V.; Salo, A. A.; Pertsev, S. F.; Rikunov, A. V.

    2013-09-01

    An attempt is undertaken to describe the development of the disturbed region of the atmosphere caused by the nuclear explosion over Hiroshima on August 6, 1945. Numerical simulation of the phenomenon is performed using the dynamic equations for a nonconducting inviscid gas taking into account the combustion of urban buildings, phase changes of water, electrification of ice particles, and removal of soot particles. The results of the numerical calculation of the development of the disturbed region indicate heavy rainfall, the formation of a storm cloud with lightning discharges, removal of soot particles, and the formation of vertical vortices. The temporal sequence of these meteorological phenomena is consistent with the data of observations. Because of the assumptions and approximations used in solving the problem, the results are of qualitative nature. Refinement of the results can be obtained by a more detailed study of the approximate initial and boundary conditions of the problem.

  17. REGIONAL SEISMIC CHEMICAL AND NUCLEAR EXPLOSION DISCRIMINATION: WESTERN U.S. EXAMPLES

    SciTech Connect

    Walter, W R; Taylor, S R; Matzel, E; Gok, R; Heller, S; Johnson, V

    2006-07-07

    We continue exploring methodologies to improve regional explosion discrimination using the western U.S. as a natural laboratory. The western U.S. has abundant natural seismicity, historic nuclear explosion data, and widespread mine blasts, making it a good testing ground to study the performance of regional explosion discrimination techniques. We have assembled and measured a large set of these events to systematically explore how to best optimize discrimination performance. Nuclear explosions can be discriminated from a background of earthquakes using regional phase (Pn, Pg, Sn, Lg) amplitude measures such as high frequency P/S ratios. The discrimination performance is improved if the amplitudes can be corrected for source size and path length effects. We show good results are achieved using earthquakes alone to calibrate for these effects with the MDAC technique (Walter and Taylor, 2001). We show significant further improvement is then possible by combining multiple MDAC amplitude ratios using an optimized weighting technique such as Linear Discriminant Analysis (LDA). However this requires data or models for both earthquakes and explosions. In many areas of the world regional distance nuclear explosion data is lacking, but mine blast data is available. Mine explosions are often designed to fracture and/or move rock, giving them different frequency and amplitude behavior than contained chemical shots, which seismically look like nuclear tests. Here we explore discrimination performance differences between explosion types, the possible disparity in the optimization parameters that would be chosen if only chemical explosions were available and the corresponding effect of that disparity on nuclear explosion discrimination. Even after correcting for average path and site effects, regional phase ratios contain a large amount of scatter. This scatter appears to be due to variations in source properties such as depth, focal mechanism, stress drop, in the near source

  18. VLA H92α and H115β Recombination Line Observations of the Galactic Center H II Regions: The Sickle (G0.18-0.04) and the Pistol (G0.15-0.05)

    NASA Astrophysics Data System (ADS)

    Lang, Cornelia C.; Goss, W. M.; Wood, O. S.

    1997-01-01

    The Very Large Array has been used in the CnB and DnC configurations to observe the remarkable Galactic center sources, the Sickle and the Pistol, near l = 0.18d, b = -0.04d. These H II regions have an unusual morphology and may be physically associated with the linear nonthermal filaments at l = 0.18d, which appear to intersect the sources. The H92α (8.31 GHz) and H115β (8.43 GHz) radio recombination lines arising from these sources have been observed with angular resolutions of 6" and 9", respectively. In addition, there is a probable detection of the helium line in the Pistol (Y+ ~ 14% +/- 6%), while in the Sickle, no helium lines were detected with an upper limit of Y+ ~ 5% (3 σ). A complex velocity field has been observed in both sources. The LSR velocity in the Sickle varies from 0 to 75 km s-1, with an average velocity of ~35 km s-1 the average velocity of the Pistol is ~115 km s-1. The recombination line properties of the Sickle and the Pistol (FWHM line widths, line-to-continuum ratios, β-to-α ratio) are consistent with photoionization from hot stars. The β-to-α line ratio of ~0.35 +/- 0.07 over most of the Sickle and Pistol does not differ significantly from the LTE value of 0.28. The average LTE electron temperature, T*e, for the Sickle (~5500 K) is similar to typical Galactic center H II regions, and T*e for the Pistol is somewhat lower (~3600 K). An additional H II component in the line profiles of three regions of the Sickle in which the nonthermal filaments are present suggests that an interaction between the ionized gas and the nonthermal filaments is occurring. The probable detection of He92α in the Pistol and the nondetection in the Sickle may be due to a difference in the radiation field of the ionizing sources.

  19. Candidate Selection for the FLAMINGOS-2 Galactic Center Survey

    SciTech Connect

    DeWitt, Curtis; Eikenberry, Stephen; Bandyopadhyay, Reba; Blum, Robert; Muno, Michael; Sellgren, Kris

    2008-05-23

    We present a JHK{sub s} catalog of a 20'x20' region around the Galactic Center observed with the ISPI camera on the 4 m CTIO telescope. The data is being used to select targets for the FLAMINGOS-2 Galactic Center Survey, which will take near-infrared spectra of thousands of GC sources in an effort to identify and characterize the unique X-ray binary source population in this region.

  20. Candidate Selection for the FLAMINGOS-2 Galactic Center Survey

    NASA Astrophysics Data System (ADS)

    Dewitt, Curtis; Eikenberry, Stephen; Bandyopadhyay, Reba; Blum, Robert; Muno, Michael; Sellgren, Kris

    2008-05-01

    We present a JHKs catalog of a 20'×20' region around the Galactic Center observed with the ISPI camera on the 4 m CTIO telescope. The data is being used to select targets for the FLAMINGOS-2 Galactic Center Survey, which will take near-infrared spectra of thousands of GC sources in an effort to identify and characterize the unique X-ray binary source population in this region.

  1. Small tumor virus genomes are integrated near nuclear matrix attachment regions in transformed cells.

    PubMed

    Shera, K A; Shera, C A; McDougall, J K

    2001-12-01

    More than 15% of human cancers have a viral etiology. In benign lesions induced by the small DNA tumor viruses, viral genomes are typically maintained extrachromosomally. Malignant progression is often associated with viral integration into host cell chromatin. To study the role of viral integration in tumorigenesis, we analyzed the positions of integrated viral genomes in tumors and tumor cell lines induced by the small oncogenic viruses, including the high-risk human papillomaviruses, hepatitis B virus, simian virus 40, and human T-cell leukemia virus type 1. We show that viral integrations in tumor cells lie near cellular sequences identified as nuclear matrix attachment regions (MARs), while integrations in nonneoplastic cells show no significant correlation with these regions. In mammalian cells, the nuclear matrix functions in gene expression and DNA replication. MARs play varied but poorly understood roles in eukaryotic gene expression. Our results suggest that integrated tumor virus genomes are subject to MAR-mediated transcriptional regulation, providing insight into mechanisms of viral carcinogenesis. Furthermore, the viral oncoproteins serve as invaluable tools for the study of mechanisms controlling cellular growth. Similarly, our demonstration that integrated viral genomes may be subject to MAR-mediated transcriptional effects should facilitate elucidation of fundamental mechanisms regulating eukaryotic gene expression.

  2. Relative Locations of the DPRK Nuclear Tests Using Regional and Teleseismic Data

    NASA Astrophysics Data System (ADS)

    Gibbons, Steven J.; Kværna, Tormod; Mykkeltveit, Svein

    2016-04-01

    Accurate relative location estimates for the announced nuclear tests carried out at the Punggye-ri test site in North Korea make it far easier to constrain the absolute coordinates of the events. With four tests now recorded well both at regional and teleseismic distances with excellent azimuthal coverage, we have a vast number of differential traveltime measurements which reduce substantially the variability in the relative location estimates. A large redundancy of data allows for independent relative location estimates for each event pair using different sets of stations and phases. Superposition of multiple grids of differential traveltime residuals results in relative event location estimates which are less sensitive to uncertainties in the time measurements or in the modelled traveltime gradients. Of particular interest is the location of the October 9, 2006, test. This event was approximately 2 km to the East of the 2009, 2013, and 2016 nuclear tests and its precise location will help to fix the template of relative locations in the terrain at the test site. This smaller event was recorded by fewer stations and with poorer signal-to-noise ratio. Due to the somewhat different source location the waveform semblance with the other events is diminished and this complicates the measurement of differential time-delays, in particular for the higher frequency regional observations. The uncertainty in the location of the 2006 event is reduced considerably by being able to be estimated relative to 3 different events with exceptionally accurate relative location estimates.

  3. Nuclear energy surfaces at high-spin in the A{approximately}180 mass region

    SciTech Connect

    Chasman, R.R.; Egido, J.L.; Robledo, L.M.

    1995-08-01

    We are studying nuclear energy surfaces at high spin, with an emphasis on very deformed shapes using two complementary methods: (1) the Strutinsky method for making surveys of mass regions and (2) Hartree-Fock calculations using a Gogny interaction to study specific nuclei that appear to be particularly interesting from the Strutinsky method calculations. The great advantage of the Strutinsky method is that one can study the energy surfaces of many nuclides ({approximately}300) with a single set of calculations. Although the Hartree-Fock calculations are quite time-consuming relative to the Strutinsky calculations, they determine the shape at a minimum without being limited to a few deformation modes. We completed a study of {sup 182}Os using both approaches. In our cranked Strutinsky calculations, which incorporate a necking mode deformation in addition to quadrupole and hexadecapole deformations, we found three well-separated, deep, strongly deformed minima. The first is characterized by nuclear shapes with axis ratios of 1.5:1; the second by axis ratios of 2.2:1 and the third by axis ratios of 2.9:1. We also studied this nuclide with the density-dependent Gogny interaction at I = 60 using the Hartree-Fock method and found minima characterized by shapes with axis ratios of 1.5:1 and 2.2:1. A comparison of the shapes at these minima, generated in the two calculations, shows that the necking mode of deformation is extremely useful for generating nuclear shapes at large deformation that minimize the energy. The Hartree-Fock calculations are being extended to larger deformations in order to further explore the energy surface in the region of the 2.9:1 minimum.

  4. Nuclear astrophysics

    SciTech Connect

    Haxton, W.C.

    1992-01-01

    The problem of core-collapse supernovae is used to illustrate the many connections between nuclear astrophysics and the problems nuclear physicists study in terrestrial laboratories. Efforts to better understand the collapse and mantle ejection are also motivated by a variety of interdisciplinary issues in nuclear, particle, and astrophysics, including galactic chemical evolution, neutrino masses and mixing, and stellar cooling by the emission of new particles. The current status of theory and observations is summarized.

  5. Nuclear astrophysics

    SciTech Connect

    Haxton, W.C.

    1992-12-31

    The problem of core-collapse supernovae is used to illustrate the many connections between nuclear astrophysics and the problems nuclear physicists study in terrestrial laboratories. Efforts to better understand the collapse and mantle ejection are also motivated by a variety of interdisciplinary issues in nuclear, particle, and astrophysics, including galactic chemical evolution, neutrino masses and mixing, and stellar cooling by the emission of new particles. The current status of theory and observations is summarized.

  6. Observations of 1-30 MeV gamma rays from the galactic center

    NASA Technical Reports Server (NTRS)

    Zanrosso, E.; Long, J. L.; Zych, A. D.; White, R. S.

    1981-01-01

    Preliminary results are reported for gamma ray observations of the galactic center region made during a 15-hour balloon flight from Alice Springs, Australia on April 18, 1979. The observations were carried out with the UGR double-scatter gamma-ray telescope at energies of 1 to 30 MeV. The observations are compatible with a galactic source of approximately equal brightness along the region of system II galactic longitudes between 300 and 60 deg. The energy distribution joins smoothly to previous spark chamber results at energies above 30 MeV and to scintillator results below 1 MeV. It appears to be a combination of nuclear gamma ray lines superimposed on a power-law bremsstrahlung spectrum. The metastable C-12 line at 4.4 MeV appears to be present with a significance of about 16 standard deviations. The flux in the line is 0.0006 + or - 0.0003 photons/sq cm per sec per rad. The oxygen line at 6.1 MeV does not seem to appear significantly above background.

  7. Metallicity of the Stars at the Galactic Center

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2015-08-01

    A recent study suggests that the stars in the central parsec of our galaxy are not a single, roughly solar-metallicity population, as previously thought. Instead, these stars have a large variation in metallicities which has interesting implications for the formation history of the Milky Ways nuclear star cluster.Clues from AbundancesWhy do we care about the metallicity of stars and stellar populations? Metallicity measurements can help us to separate multiple populations of stars and figure out when and where they were formed.Measurements of the chemical abundances of stars in the Milky Way have demonstrated that theres a metallicity gradient in the galaxy: on average, its below solar metallicity at the outer edges of the disk and increases to above solar metallicity within the central 5 kpc of the galaxy.So far, measurements of stars in the very center of the galaxy are consistent with this galactic trend: theyre all slightly above solar metallicity, with little variation between them. But these measurements exist for only about a dozen stars within the central 10 pc of the galaxy! Due to the high stellar density in this region, a larger sample is needed to get a complete picture of the abundances and thats what this study set out to find.Different PopulationsLed by Tuan Do (Dunlap Fellow at the University of Toronto and member of the Galactic Center Group at UCLA), the authors of this study determined the metallicities of 83 late-type giant stars within the central parsec of the galaxy. The metallicities were found by fitting the stars K-band spectra from observations by the NIFS instrument on the Gemini North telescope.In contrast to the previous studies, the authors found that the 83 stars exhibited a wide range of metallicities, from a tenth of solar metallicity all the way to super-solar metallicities.The abundances of the low-metallicity stars they found are consistent with globular cluster metallicities, suggesting that these stars (about 6% of the sample

  8. Local, Regional and National Responses for Medical Management of a Radiological/Nuclear Incident

    PubMed Central

    Dainiak, Nicholas; Skudlarska, Beata; Albanese, Joseph

    2013-01-01

    Radiological and nuclear devices may be used by terrorists or may be the source of accidental exposure. A tiered approach has been recommended for response to a terrorist event wherein local, regional, state and federal assets become involved sequentially, as the magnitude in severity of the incident increases. State-wide hospital plans have been developed and published for Connecticut, New York and California. These plans address delineation of responsibilities of various categories of health professionals, protection of healthcare providers, identification and classification of individuals who might have been exposed to and/or contaminated by radiation and, in the case of Connecticut response plan, early management of victims. Regional response programs such as the New England Regional Health Compact (consisting of 6 member states) have been developed to manage consequences of radiation injury. The Department of Homeland Security is ultimately responsible for managing both health consequences and the crisis. Multiple US national response assets may be called upon for use in radiological incidents. These include agencies and programs that have been developed by the Department of Energy, the Environmental Protection Agency and the Department of Defense. Coordination of national, regional and state assets with local response efforts is necessary to provide a timely and efficient response. PMID:23447742

  9. Aberration in proper motions for Galactic stars

    NASA Astrophysics Data System (ADS)

    Liu, J.-C.; Xie, Y.; Zhu, Z.

    2014-12-01

    Accelerations of both the solar system barycenter (SSB) and stars in the MilkyWay cause a systematic observational effect on the stellar proper motions, which was first studied by J. Kovalevsky (2003). This paper intends to extend that work and aims to estimate the magnitude and significance of the aberration in proper motions of stars, especially in the region near the Galactic center (GC). We adopt two models for the Galactic rotation curve to evaluate the aberrational effect on the Galactic plane. We show that the effect of aberration in proper motions depends on the galactocentric distance of stars; it is dominated by the acceleration of stars in the central region of the Galaxy. Then we investigate the applicability of the theoretical expressions: if the orbital period of stars is only a fraction of the light time from the star to the SSB, the expression with approximation proposed by Kovalevsky is not appropriate. With a more suitable formulation, we found that the aberration has no effect on the determination of the stellar orbits on the celestial sphere. In the future this aberrational effect under consideration should be considered with high-accurate astrometry, particularly in constructing the Gaia celestial reference system realized by Galactic stars.

  10. AN ABSENCE OF FAST RADIO BURSTS AT INTERMEDIATE GALACTIC LATITUDES

    SciTech Connect

    Petroff, E.; Van Straten, W.; Bailes, M.; Barr, E. D.; Coster, P.; Flynn, C.; Keane, E. F.; Johnston, S.; Bates, S. D.; Keith, M. J.; Kramer, M.; Stappers, B. W.; Bhat, N. D. R.; Burgay, M.; Possenti, A.; Tiburzi, C.; Burke-Spolaor, S.; Champion, D.; Ng, C.; Levin, L.; and others

    2014-07-10

    Fast radio bursts (FRBs) are an emerging class of bright, highly dispersed radio pulses. Recent work by Thornton et al. has revealed a population of FRBs in the High Time Resolution Universe (HTRU) survey at high Galactic latitudes. A variety of progenitors have been proposed, including cataclysmic events at cosmological distances, Galactic flare stars, and terrestrial radio frequency interference. Here we report on a search for FRBs at intermediate Galactic latitudes (–15° region. Several effects such as dispersion, scattering, sky temperature, and scintillation decrease the sensitivity by more than 3σ in ∼20% of survey pointings. Including all of these effects, we exclude the hypothesis that FRBs are uniformly distributed on the sky with 99% confidence. This low probability implies that additional factors—not accounted for by standard Galactic models—must be included to ease the discrepancy between the detection rates at high and low Galactic latitudes. A revised rate estimate or another strong and heretofore unknown selection effect in Galactic latitude would provide closer agreement between the surveys' detection rates. The dearth of detections at low Galactic latitude disfavors a Galactic origin for these bursts.

  11. An Absence of Fast Radio Bursts at Intermediate Galactic Latitudes

    NASA Astrophysics Data System (ADS)

    Petroff, E.; van Straten, W.; Johnston, S.; Bailes, M.; Barr, E. D.; Bates, S. D.; Bhat, N. D. R.; Burgay, M.; Burke-Spolaor, S.; Champion, D.; Coster, P.; Flynn, C.; Keane, E. F.; Keith, M. J.; Kramer, M.; Levin, L.; Ng, C.; Possenti, A.; Stappers, B. W.; Tiburzi, C.; Thornton, D.

    2014-07-01

    Fast radio bursts (FRBs) are an emerging class of bright, highly dispersed radio pulses. Recent work by Thornton et al. has revealed a population of FRBs in the High Time Resolution Universe (HTRU) survey at high Galactic latitudes. A variety of progenitors have been proposed, including cataclysmic events at cosmological distances, Galactic flare stars, and terrestrial radio frequency interference. Here we report on a search for FRBs at intermediate Galactic latitudes (-15° region. Several effects such as dispersion, scattering, sky temperature, and scintillation decrease the sensitivity by more than 3σ in ~20% of survey pointings. Including all of these effects, we exclude the hypothesis that FRBs are uniformly distributed on the sky with 99% confidence. This low probability implies that additional factors—not accounted for by standard Galactic models—must be included to ease the discrepancy between the detection rates at high and low Galactic latitudes. A revised rate estimate or another strong and heretofore unknown selection effect in Galactic latitude would provide closer agreement between the surveys' detection rates. The dearth of detections at low Galactic latitude disfavors a Galactic origin for these bursts.

  12. Expression, function, and targeting of the nuclear exporter chromosome region maintenance 1 (CRM1) protein.

    PubMed

    Ishizawa, Jo; Kojima, Kensuke; Hail, Numsen; Tabe, Yoko; Andreeff, Michael

    2015-09-01

    Nucleocytoplasmic trafficking of proteins/RNAs is essential to normal cellular function. Indeed, accumulating evidence suggests that cancer cells escape anti-neoplastic mechanisms and benefit from pro-survival signals via the dysregulation of this system. The nuclear exporter chromosome region maintenance 1 (CRM1) protein is the only protein in the karyopherin-β protein family that contributes to the trafficking of numerous proteins and RNAs from the nucleus. It is considered to be an oncogenic, anti-apoptotic protein in transformed cells, since it reportedly functions as a gatekeeper for cell survival, including affecting p53 function, and ribosomal biogenesis. Furthermore, abnormally high expression of CRM1 is correlated with poor patient prognosis in various malignancies. Therapeutic targeting of CRM1 has emerged as a novel cancer treatment strategy, starting with a clinical trial with leptomycin B, the original specific inhibitor of CRM1, followed by development of several next-generation small molecules. KPT-330, a novel member of the CRM1-selective inhibitors of nuclear export (SINE) class of compounds, is currently undergoing clinical evaluation for the therapy of various malignancies. Results from these trials suggest that SINE compounds may be particularly useful against hematological malignancies, which often become refractory to standard chemotherapeutic agents.

  13. FAST TRACK PAPER: Regional observations of the second North Korean nuclear test on 2009 May 25

    NASA Astrophysics Data System (ADS)

    Shin, Jin Soo; Sheen, Dong-Hoon; Kim, Geunyoung

    2010-01-01

    The suspicious seismic event that occurred in the northern Korean Peninsula on 2009 May 25 was declared to be the second underground nuclear test (NK2ND) by North Korea. We investigated the characteristics of NK2ND using seismic signals recorded at regional-distance stations in South Korea and China. The Pn/Lg ratios of NK2ND definitely discriminate this event from two nearby natural earthquakes at frequencies above 4 Hz. Full moment tensor inversion of full waveform data shows that NK2ND had a very large isotropic component. Pure isotropic moment tensor inversion also resulted in good recovery of observed waveforms, with clear indication that NK2ND was explosive in origin. The moment magnitude (Mw) from the full moment tensor inversion was estimated to be 4.5 and network-averaged values of 4.6 and 3.6 were calculated for rms mb(Lg) and Ms(VMAX), respectively. Although mb - Ms signature has been considered one of the most reliable discriminants for separating explosions and earthquakes, this signature showed poor discrimination in the case of NK2ND. The Pn/Lg ratios and moment tensor inversion give more reliable evidence than does the mb - Ms for classifying the suspicious event in the northern Korean Peninsula as a possible explosion. The characteristics of NK2ND are also quite similar to those of the first North Korean nuclear test on 2006 October 9.

  14. Expression, function, and targeting of the nuclear exporter chromosome region maintenance 1 (CRM1) protein

    PubMed Central

    Ishizawa, Jo; Kojima, Kensuke; Hail, Numsen; Tabe, Yoko; Andreeff, Michael

    2015-01-01

    Nucleocytoplasmic trafficking of proteins/RNAs is essential to normal cellular function. Indeed, accumulating evidence suggests that cancer cells escape anti-neoplastic mechanisms and benefit from pro-survival signals via the dysregulation of this system. The nuclear exporter chromosome region maintenance 1 (CRM1) protein is the only protein in the karyopherin-β protein family that contributes to the trafficking of numerous proteins and RNAs from the nucleus. It is considered to be an oncogenic, anti-apoptotic protein in transformed cells, since it reportedly functions as a gatekeeper for cell survival, including affecting p53 function, and ribosomal biogenesis. Furthermore, abnormally high expression of CRM1 is correlated with poor patient prognosis in various malignancies. Therapeutic targeting of CRM1 has emerged as a novel cancer treatment strategy, starting with a clinical trial with leptomycin B, the original specific inhibitor of CRM1, followed by development of several next-generation small molecules. KPT-330, a novel member of the CRM1-selective inhibitors of nuclear export (SINE) class of compounds, is currently undergoing clinical evaluation for the therapy of various malignancies. Results from these trials suggest that SINE compounds may be particularly useful against hematological malignancies, which often become refractory to standard chemotherapeutic agents. PMID:26048327

  15. Allopolyploid speciation in Persicaria (Polygonaceae): Insights from a low-copy nuclear region

    PubMed Central

    Kim, Sang-Tae; Sultan, Sonia E.; Donoghue, Michael J.

    2008-01-01

    Using a low-copy nuclear gene region (LEAFY second intron) we show multiple instances of allopolyploid speciation in Persicaria (Polygonaceae), which includes many important weeds. Fifteen species seem to be allopolyploids, which is higher than the number found in previous comparisons of chloroplast DNA and nuclear ribosomal internal transcribed spacer (nrITS) phylogenies. This underestimation of the extent of allopolyploidy is due in at least three cases to homogenization of nrITS toward the maternal lineage. One of the diploid species, P. lapathifolia, has been involved in at least six cases of allopolyploid speciation. Of the diploids, this species is the most widespread geographically and ecologically and also bears more numerous and conspicuous flowers, illustrating ecologic factors that may influence hybridization frequency. With a few exceptions, especially the narrowly endemic hexaploid, P. puritanorum, the allopolyploid species also are widespread, plastic, ecological generalists. Hybridization events fostered by human introductions may be fueling the production of new species that have the potential to become aggressive weeds. PMID:18711129

  16. Discovery of Two Supernovae in the Nuclear Regions of the Luminous Infrared Galaxy IC 883

    NASA Astrophysics Data System (ADS)

    Kankare, E.; Mattila, S.; Ryder, S.; Väisänen, P.; Alberdi, A.; Alonso-Herrero, A.; Colina, L.; Efstathiou, A.; Kotilainen, J.; Melinder, J.; Pérez-Torres, M.-A.; Romero-Cañizales, C.; Takalo, A.

    2012-01-01

    We report the discovery of two consecutive supernovae (SNe), 2010cu and 2011hi, located at 0farcs37 (180 pc) and 0farcs79 (380 pc) projected distance, respectively, from the center of the K-band nucleus of the luminous infrared galaxy (LIRG) IC 883. The SNe were discovered in an ongoing near-infrared K-band search for core-collapse SNe in such galaxies using the ALTAIR/NIRI adaptive optics system with laser guide star at the Gemini-North Telescope. These are thus the closest SNe yet discovered to an LIRG nucleus in optical or near-infrared wavelengths. The near-infrared light curves and colors of both SNe are consistent with core-collapse events. Both SNe seem to suffer from relatively low host galaxy extinction suggesting that regardless of their low projected galactocentric distances, they are not deeply buried in the nuclear regions of the host galaxy.

  17. Investigation of nuclear shell structure far from stability in the region of {sup 78}Ni

    SciTech Connect

    Sahin, E.

    2008-11-11

    Neutron rich nuclei close to shell closures play an important role on recent nuclear structure studies since they allow to search for possible modifications of single-particle energies, thus a possible shell evolution with increasing N/Z ratio. Their high-spin states will be unique observable in order to understand the size and eventually the evolution of the energy gaps far from stability. In such context, the {sup 83}As, {sup 82}Ge, and {sup 81}Ga nuclei located in the {sup 78}Ni region have been studied in Legnaro National Laboratory (LNL) and we will present our experimental results on the single-particle structure of these nuclei as well as the evolution of the N = 50 shell gap size.

  18. Galactic-scale civilization

    NASA Technical Reports Server (NTRS)

    Kuiper, T. B. H.

    1980-01-01

    Evolutionary arguments are presented in favor of the existence of civilization on a galactic scale. Patterns of physical, chemical, biological, social and cultural evolution leading to increasing levels of complexity are pointed out and explained thermodynamically in terms of the maximization of free energy dissipation in the environment of the organized system. The possibility of the evolution of a global and then a galactic human civilization is considered, and probabilities that the galaxy is presently in its colonization state and that life could have evolved to its present state on earth are discussed. Fermi's paradox of the absence of extraterrestrials in light of the probability of their existence is noted, and a variety of possible explanations is indicated. Finally, it is argued that although mankind may be the first occurrence of intelligence in the galaxy, it is unjustified to presume that this is so.

  19. The Galactic Bulge

    NASA Astrophysics Data System (ADS)

    Barbuy, B.

    2016-06-01

    The Galactic bulge is the least studied component of our Galaxy. Yet, its formation and evolution are key to understand the formation of the Galaxy itself. Studies on the Galactic bulge have increased significantly in the last years, but still there are many points of controversy. This volume contains several contributions from experts in different aspects of the bulge. Issues discussed include the following: the presence of an old spheroidal bulge, or identification of its old stellar population with the thick disk or halo; fraction of stars younger than 10 Gyr is estimated to be of < 5 to 22% depending on method and authors; multiple populations or only a metal-poor and a metal-rich ones; spheroidal or ellipsoidal distribution of RR Lyrae; formation of the bulge from early mergers or from secular evolution of the bar; different methods of mapping extinction; selection and identification of bulge globular clusters.

  20. Grains in galactic haloes.

    NASA Astrophysics Data System (ADS)

    Ferrara, A.; Barsella, B.; Ferrini, F.; Greenberg, J. M.; Aiello, S.

    1989-12-01

    The authors considered the effect of extensive forces on dust grains subjected to the light and matter distribution of the spiral galaxy NGC 3198. They have shown that the combined force on a small particle located above the plane of a galactic disk may be either attractive or repulsive depending on a variety of parameters. The authors present here the preliminary results of the study of the motion of a dust grain for NGC 3198.

  1. Galactic Diffuse Emissions

    SciTech Connect

    Digel, Seth W.; /SLAC

    2007-10-25

    Interactions of cosmic rays with interstellar nucleons and photons make the Milky Way a bright, diffuse source of high-energy {gamma}-rays. Observationally, the results from EGRET, COMPTEL, and OSSE have now been extended to higher energies by ground-based experiments, with detections of diffuse emission in the Galactic center reported by H.E.S.S. in the range above 100 GeV and of diffuse emission in Cygnus by MILAGRO in the TeV range. In the range above 100 keV, INTEGRAL SPI has found that diffuse emission remains after point sources are accounted for. I will summarize current knowledge of diffuse {gamma}-ray emission from the Milky Way and review some open issues related to the diffuse emission -- some old, like the distribution of cosmic-ray sources and the origin of the 'excess' of GeV emission observed by EGRET, and some recently recognized, like the amount and distribution of molecular hydrogen not traced by CO emission -- and anticipate some of the advances that will be possible with the Large Area Telescope on GLAST. We plan to develop an accurate physical model for the diffuse emission, which will be useful for detecting and accurately characterizing emission from Galactic point sources as well as any Galactic diffuse emission from exotic processes, and for studying the unresolved extragalactic emission.

  2. An X-ray study of the galactic center

    NASA Technical Reports Server (NTRS)

    Watson, M. G.; Willingale, R.; Hertz, P.; Grindlay, J. E.

    1981-01-01

    The results from two long observations with the Einstein Observatory Imaging Proportional Counter (IPC) of an approximately 1 x 1 deg field centered near the galactic nucleus are presented. The X-ray images reveal a complex of weak sources within 20 arcmin of the galactic nucleus (Sgr A West) together with a region of apparently diffuse emission about 25 x 15 arcmin in extent. Three of the sources are tentatively identified: two with nearby galactic objects, and a third positionally coincident with Sgr A West itself (within the arcmin-accuracy available with the IPC). The nature of this source and the implications of both the high source density and presence of diffuse emission in the galactic center region are discussed.

  3. The European Galactic Plane Surveys: EGAPS

    NASA Astrophysics Data System (ADS)

    Groot, P. J.; Drew, J.; Greimel, R.; Gaensicke, B.; Knigge, C.; Irwin, M.; Mampaso, A.; Augusteijn, T.; Morales-Rueda, L.; Barlow, M.; Iphas Collaboration; Uvex Collaboration; Vphas+ Collaboration

    2006-08-01

    Introduction: The European Galactic Plane Surveys (EGAPS) will for the first time ever map the complete galactic plane (10x360 degrees) down to 21st magnitude in u', g', r', i' and H-alpha and partly in He I 5875. It will complete a database of ~1 billion objects. The aim of EGAPS is to study populations of short-lived stellar and binary phases in our Galaxy and combine these population studies with stellar and binary evolutionary codes to vastly improve our understanding of crucial phases of stellar evolution. Target populations include Wolf-Rayet stars, planetary nebulae, white dwarfs (in binaries), cataclysmic variables and other mass-transferring binaries. Methods: EGAPS is using the INT+WFC on La Palma for the Northern Hemisphere and will use the VST+Omegacam in the Southern Hemisphere. Results: The Northern red survey (IPHAS, using r', i', and Halpha) has started in 2003 and is currently 70% complete. The northern blue survey (UVEX; u',g',r' and HeI) has started in June 2006. Results include the detection of a number of rare planetary nebulae, cataclysmic variables, red-dwarf white dwarf binaries in clusters, a possible AM CVn candidate, and a deep photometric and spectroscopic investigation of the Cyg X region. Discussion: EGAPS will revolutionize the field of galactic stellar astrophysics by completing the first ever digital, multicolour survey of the Galactic Plane.

  4. Molecular gas near the galactic center

    SciTech Connect

    Heiligman, G.M.

    1982-01-01

    The interstellar matter within 400 pc of the center of our Galaxy was studied using millimeter-wave spectroscopy. The region -2/sup 0/.0less than or equal to + 2/sup 0/.0, -0/sup 0/.467 less than or equal to b less than or equal to + 0/sup 0/.467 was surveyed in the lambda = 2.72 mm transition of /sup 13/CO at spacings of 0/sup 0/.067 and 0/sup 0/.133 in l and b respectively. Fourteen distinct kinematic features were identified in the maps of these data; four of the features had not been described before in molecular surveys. Most of the high-velocity features and the nuclear disk are tilted to the galactic plane by 7/sup 0/ and inclined to the line of sight by 72/sup 0/, but the sheet of high-density gas which surrounds Sgr A and B is not measurably tilted. Spectra of the /sup 12/CO and C/sup 18/O emission lines near lambda = 2.60 and 2.73 mm were taken along eight lines of sight within the survey region to estimate the excitation temperatures and column densities: two 16' x 16' densely sampled maps were made in /sup 13/CO to estimate cloud sizes. Isocyanic acid (HNCO) was fortuitously found at four of these positions in emission with large velocity widths. Two forms of molecular gas were seen in the central region: (1) clouds with radii of 20 pc, excitation temperatures approximately 8 K, and mass of approximately 10/sup 5/ mass of sun and (2) diffuse regions with T/sub x/ of 25K, densities of > 5 x 10/sup 4/ cm/sup -3/, and linewidths > 30 km s/sup -1/. A total mass of roughly 1.2 x 10/sup 8/ Mass of sun was derived for the interstellar matter in the inner 400 pc of the Galaxy. A model of closed orbits in a barlike bulge potential was developed to simulate the kinematic motions of the gas in the inner 400 pc of the Galaxy. The modelaccounts for most but not all of the high-velocity features, the + 135 km s/sup -1/ expanding arm being the most difficult to explain.

  5. Stability of Gas Clouds in Galactic Nuclei: An Extended Virial Theorem

    NASA Astrophysics Data System (ADS)

    Chen, Xian; Amaro-Seoane, Pau; Cuadra, Jorge

    2016-03-01

    Cold gas entering the central 1-102 pc of a galaxy fragments and condenses into clouds. The stability of the clouds determines whether they will be turned into stars or can be delivered to the central supermassive black hole (SMBH) to turn on an active galactic nucleus (AGN). The conventional criteria to assess the stability of these clouds, such as the Jeans criterion and Roche (or tidal) limit, are insufficient here, because they assume the dominance of self-gravity in binding a cloud, and neglect external agents, such as pressure and tidal forces, which are common in galactic nuclei. We formulate a new scheme for judging this stability. We first revisit the conventional Virial theorem, taking into account an external pressure, to identify the correct range of masses that lead to stable clouds. We then extend the theorem to further include an external tidal field, which is equally crucial for the stability in the region of our interest—in dense star clusters, around SMBHs. We apply our extended Virial theorem to find new solutions to controversial problems, namely, the stability of the gas clumps in AGN tori, the circum-nuclear disk in the Galactic Center, and the central molecular zone of the Milky Way. The masses we derive for these structures are orders of magnitude smaller than the commonly used Virial masses (equivalent to the Jeans mass). Moreover, we prove that these clumps are stable, contrary to what one would naively deduce from the Roche (tidal) limit.

  6. New Resolved Resonance Region Evaluation for 63Cu and 65Cu for Nuclear Criticality Safety Program

    SciTech Connect

    Sobes, Vladimir; Leal, Luiz C; Guber, Klaus H; Forget, Benoit; Kopecky, S.; Schillebeeckx, P.; Siegler, P.

    2014-01-01

    A new resolved resonance region evaluation of 63Cu and 65Cu was done in the energy region from 10-5 eV to 99.5 keV. The R-Matrix SAMMY method using the Reich-Moore approximation was used to create a new set of consistent resonance parameters. The new evaluation was based on three experimental transmission data sets; two measured at ORELA and one from MITR, and two radiative capture experimental data sets from GELINA. A total of 141 new resonances were identied for 63Cu and 117 for 65Cu. The corresponding set of external resonances for each isotope was based on the identied resonances above 99.5 keV from the ORELA transmission data. The negative external levels (bound levels) were determined to match the dierential thermal cross section measured at the MITR. Double dierential elastic scattering cross sections were calculated from the new set of resonance parameters. Benchmarking calculations were carried out on a set of ICSBEP benchmarks. This work is in support of the DOE Nuclear Criticality Safety Program.

  7. On the diffuse soft X-ray emission from the nuclear region of M51

    NASA Astrophysics Data System (ADS)

    Liu, Ji-Ren; Mao, Shu-De

    2015-12-01

    We present an analysis of the diffuse soft X-ray emission from the nuclear region of M51 combining both XMM-Newton RGS and Chandra data. Most of the RGS spectrum of M51 can be fitted with a thermal model with a temperature of ∼ 0.5 keV except for the O VII triplet, which is forbidden-line dominated. The Fe L-shell lines peak around the southern cloud, where the O VIII and N VII Lyα lines also peak. In contrast, the peak of the O VII forbidden line is about 10″ offset from that of the other lines, indicating that it is from a spatially distinct component. The spatial distribution of the O VII triplet mapped by the Chandra data shows that most of the O VII triplet flux is located at faint regions near edges, instead of the southern cloud where other lines peak. This distribution of the O VII triplet is inconsistent with the photoionization model. Other mechanisms that could produce the anomalous O VII triplet, including a recombining plasma and charge exchange X-ray emission, are discussed.

  8. Near-IR 2D-spectroscopy of the 4''x 4'' region around the Active Galactic Nucleus of NGC 1068 with ISAAC/VLT

    NASA Astrophysics Data System (ADS)

    Galliano, E.; Alloin, D.

    2002-10-01

    New near-IR long slit spectroscopic data obtained with ISAAC on VLT/ANTU (ESO/Paranal) complement and extend our previously published near-IR data (Alloin et al. \\cite{all01}) to produce Brgamma and H2 emission line maps and line profile grids of the central 4'' x 4'' region surrounding the central engine of NGC 1068. The seeing quality together with the use of an 0.3'' wide slit and 0.3'' slit position offsets allow one to perform 2D-spectroscopy at a spatial resolution ~ 0.5''. Slit orientations (PA = 102 degr and PA = 12 degr) were chosen so as to match respectively the equatorial plane and the axis of the suspected molecular/dusty torus in NGC 1068. The selected wavelength range from 2.1 to 2.2μm is suitable to detect and analyze the Brgamma and H2 emission lines at a spectral resolution corresponding to 35km s-1. An asymmetric distribution of H2 emission around the continuum peak is observed. No H2 emission is detected at the location of the strong 2.2μm continuum core (coincident within error-bars with the central engine location), while two conspicuous knots of H2 emission are detected at about 1'' on each side of the central engine along PA = 90 degr, with a projected velocity difference of 140km s-1: this velocity jump has been interpreted in Alloin et al. (\\cite{all01}) as the signature of a rotating disk of molecular material. From this new data set, we find that only very low intensity Brgamma emission is detected at the location of the two main knots of H2 emission. Another knot with both H2 and Brgamma emission is detected to the North of the central engine, close to the radio source C where the small scale radio jet is redirected and close to the brightest [OIII] cloud NLR-B. It has a counterpart to the South, placed almost symmetrically with respect to the central engine, although mainly visible in the Brgamma emission. The northern and southern knots appear to be related to the ionization cone. At the achieved spectral resolution, the H2

  9. What Is Nuclear Medicine?

    MedlinePlus

    ... known as cosmic radiation, is in the upper atmosphere due to solar and galactic emissions. A typical ... used in medical procedures. 4 Cosmic Radiation Sun - - + - Atmosphere - + +- + + Earth How many nuclear medicine procedures are performed ...

  10. Economic impact of accelerated cleanup on regions surrounding the U.S. DOE's major nuclear weapons sites.

    PubMed

    Greenberg, M; Solitare, L; Frisch, M; Lowrie, K

    1999-08-01

    The regional economic impacts of the U.S. Department of Energy's accelerated environmental cleanup plan are estimated for the major nuclear weapons sites in Colorado, Idaho, New Mexico, South Carolina, Tennessee, and Washington. The analysis shows that the impact falls heavily on the three relatively rural regions around the Savannah River (SC), Hanford (WA), and Idaho National Engineering and Environmental Laboratory (ID) sites. A less aggressive phase-down of environmental management funds and separate funds to invest in education and infrastructure in the regions helps buffer the impacts on jobs, personal income, and gross regional product. Policy options open to the federal and state and local governments are discussed.

  11. Galactic worms. I - Catalog of worm candidates

    NASA Technical Reports Server (NTRS)

    Koo, Bon-Chul; Heiles, Carl; Reach, William T.

    1992-01-01

    A catalog of candidates for the Galactic worms that are possibly the walls surrounding the superbubbles is compiled; 118 isolated structures that appear both in H I and in IR (60 and 100 microns). Fifty-two are possibly associated with H II regions. It is found that the 100-micron emissivity increases systematically toward the Galactic interior, which is consistent with the increase of the general interstellar radiation field. The 100-micron emissivity of the structures associated with the H II regions is larger than that of the structures without associated H II regions. The 60-100-micron ratio is large, 0.28 +/- 0.03, which may indicate that the grains associated with the atomic gas have a relatively large population of small grains. Thirty-five structures appear in the 408-MHz continuum. The IR and the radio continuum properties suggest that the 408-MHz continuum emission in those structures is very likely thermal. The implications of these results on the ionization of gas far from the Galactic plane are discussed.

  12. Spatially Resolved Far-Ultraviolet Spectroscopy of the Nuclear Region of NGC 1068

    NASA Astrophysics Data System (ADS)

    Zheng, Wei; Wang, Jun-Xian; Kriss, Gerard A.; Sahnow, David; Allen, Mark; Dopita, Michael; Tsvetanov, Zlatan; Bicknell, Geoffrey

    2008-10-01

    We carry out high-resolution FUSE spectroscopy of the nuclear region of NGC 1068. The first set of spectra was obtained with a 30'' square aperture that collected all emission from the narrow-line region. The data reveal a strong broad O VI component of FWHM ~3500 km s-1 and two narrow O VI λλ1031, 1037 components of ~350 km s-1. The C III λ977 and N III λ991 emission lines in this spectrum can be fitted with a narrow component of FWHM ~1000 km s-1 and a broad one of ~2500 km s-1. Another set of seven spatially resolved spectra was made using a long slit of 1.25'' × 20'' at steps of ~1'' along the axis of the emission-line cone. We find the following: (1) Major emission lines in the FUSE wavelength range consist of a broad and a narrow component. (2) There is a gradient in the velocity field for the narrow O VI component of ~200 km s-1 from ~2'' southwest of the nucleus to ~4'' northeast. A similar pattern is also observed with the broad O VI component, with a gradient of ~3000 km s-1. These are consistent with the HST STIS findings and suggest a biconical structure in which the velocity field is mainly radial outflow. (3) A major portion of the C III and N III line flux is produced in the compact core. They are therefore not effective temperature diagnostics for the conical region. (4) The best-fit UV continuum suggests virtually no reddening, and the He II I(λ1640)/I(λ1085) ratio suggests a consistently low extinction factor across the cone. At ~2'' northeast of the nucleus there is a region characterized by (a) a strong Lyα flux but normal C IV flux, (b) a broad O VI line, and (c) a significantly enhanced C III flux. Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer (FUSE), which is operated for NASA by The Johns Hopkins University under NASA contract NAS5-32985, and observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of

  13. Radioactivity in the galactic plane

    NASA Technical Reports Server (NTRS)

    Walraven, G. D.; Haymes, R. C.

    1976-01-01

    The paper reports the detection of a large concentration of interstellar radioactivity during balloon-altitude measurements of gamma-ray energy spectra in the band between 0.02 and 12.27 MeV from galactic and extragalactic sources. Enhanced counting rates were observed in three directions towards the plane of the Galaxy; a power-law energy spectrum is computed for one of these directions (designated B 10). A large statistical deviation from the power law in a 1.0-FWHM interval centered near 1.16 MeV is discussed, and the existence of a nuclear gamma-ray line at 1.15 MeV in B 10 is postulated. It is suggested that Ca-44, which emits gamma radiation at 1.156 MeV following the decay of radioactive Sc-44, is a likely candidate for this line, noting that Sc-44 arises from Ti-44 according to explosive models of supernova nucleosynthesis. The 1.16-MeV line flux inferred from the present data is shown to equal the predicted flux for a supernova at a distance of approximately 3 kpc and an age not exceeding about 100 years.

  14. Explosive Nuclear Burning in the pp-Chain Region and the Breakout Processes

    NASA Astrophysics Data System (ADS)

    Kubono, S.; Yamaguchi, H.; Hayakawa, S.; Hou, S. Q.; He, J. J.

    2016-02-01

    The nuclear reactions in the pp-chain region and on the breakout process from the pp-chain region under very high temperature conditions are reviewed, and some possibilities for experimental investigation are discussed. The reactions discussed could play an important role typically for the primordial nucleosynthesis and supernova nucleosynthesis. Specifically, I discuss here the reactions starting from the two key nuclei, 7Be and 7Li. The 7Be(n,α) reaction, which destroys 7Be, is considered to have a large impact to the primordial 7Li problem. Our recent estimate of the reaction rate indicates that the reaction rate can be about one order of magnitude smaller than the rate currently adopted, suggesting this channel has a minor effect for the 7Li problem. Under a proton-rich environment at high temperature like the νp-process, the 7Be(α,γ)11C(α,p)14N pathway is expected to play a majpr role for heavy element synthesis, comparable to the triple alpha process. These two reactions on the pathway were investigated by using low-energy, high-intensity RI beams of 7Be and 11C. The results support the theoretical prediction of heavy nucleus production at around mass 90-100 by the νp-process, where the anomalously abundant p-nuclei exist. The reactions on the breakout sequence of 7Li(n,γ)8Li(α,n)11B are also discussed which could paly a crucial role in nuetron-rich envirnments, like in the primirdial universe as well as the early stage of the r-process. The cross sections of the first step reaction 7Li(n,γ)8Li seems well confirmed, but the second step reaction 8Li(α,n)11B still is not well known yet, whose status of the study is discussed.

  15. The diffuse galactic gamma radiation - The Compton contribution and component separation by energy interval and galactic coordinates

    NASA Technical Reports Server (NTRS)

    Kniffen, D. A.; Fichtel, C. E.

    1981-01-01

    The diffuse high-energy galactic gamma radiation to be expected from cosmic ray interactions with matter and photons is considered with particular emphasis on the contribution of Compton radiation from cosmic ray electrons. The intensity, spectrum and spatial distribution of the expected galactic gamma radiation are estimated based on models of the matter, cosmic ray and photon distributions to take into account the contributions of bremsstrahlung, high-energy cosmic-ray nucleon and interstellar matter interactions as well as Compton interactions between cosmic ray electrons and background photons. Results suggest that the Compton gamma ray contribution from cosmic ray electron interactions with galactic visible and infrared photons is substantially larger than previously believed. Analysis of the energy spectra and latitude dependence of the various sources reveals that the Compton radiation, bremsstrahlung and nuclear cosmic ray-matter interaction radiation should be separable, with Compton radiation dominating at energies from 10 to 100 MeV at galactic latitudes greater than several degrees. Results demonstrate the potential of gamma ray observations in studies of galactic structure, cosmic ray electrons and galactic photon density.

  16. Excitation of the molecular gas in the nuclear region of M 82

    NASA Astrophysics Data System (ADS)

    Loenen, A. F.; van der Werf, P. P.; Güsten, R.; Meijerink, R.; Israel, F. P.; Requena-Torres, M. A.; García-Burillo, S.; Harris, A. I.; Klein, T.; Kramer, C.; Lord, S.; Martín-Pintado, J.; Röllig, M.; Stutzki, J.; Szczerba, R.; Weiß, A.; Philipp-May, S.; Yorke, H.; Caux, E.; Delforge, B.; Helmich, F.; Lorenzani, A.; Morris, P.; Philips, T. G.; Risacher, C.; Tielens, A. G. G. M.

    2010-10-01

    We present high-resolution HIFI spectroscopy of the nucleus of the archetypical starburst galaxy M 82. Six 12CO lines, 2 13CO lines and 4 fine-structure lines have been detected. Besides showing the effects of the overall velocity structure of the nuclear region, the line profiles also indicate the presence of multiple components with different optical depths, temperatures, and densities in the observing beam. The data have been interpreted using a grid of PDR models. It is found that the majority of the molecular gas is in low density (n = 103.5 cm-3) clouds, with column densities of NH = 1021.5 cm-2 and a relatively low UV radiation field (G0 = 102). The remaining gas is predominantly found in clouds with higher densities (n = 105 cm-3) and radiation fields (G0 = 102.75), but somewhat lower column densities (NH = 1021.2 cm-2). The highest J CO lines are dominated by a small (1% relative surface filling) component, with an even higher density (n = 106 cm-3) and UV field (G0 = 103.25). These results show the strength of multi-component modelling for interpretating the integrated properties of galaxies.

  17. THE GALACTIC MAGNETIC FIELD

    SciTech Connect

    Jansson, Ronnie; Farrar, Glennys R.

    2012-12-10

    With this Letter, we complete our model of the Galactic magnetic field (GMF), by using the WMAP7 22 GHz total synchrotron intensity map and our earlier results to obtain a 13-parameter model of the Galactic random field, and to determine the strength of the striated random field. In combination with our 22-parameter description of the regular GMF, we obtain a very good fit to more than 40,000 extragalactic Faraday rotation measures and the WMAP7 22 GHz polarized and total intensity synchrotron emission maps. The data call for a striated component to the random field whose orientation is aligned with the regular field, having zero mean and rms strength Almost-Equal-To 20% larger than the regular field. A noteworthy feature of the new model is that the regular field has a significant out-of-plane component, which had not been considered earlier. The new GMF model gives a much better description of the totality of data than previous models in the literature.

  18. Establishment of data base of regional seismic recordings from earthquakes, chemical explosions and nuclear explosions in the Former Soviet Union

    SciTech Connect

    Ermolenko, N.A.; Kopnichev, Yu.F.; Kunakov, V.G.; Kunakova, O.K.; Rakhmatullin, M.Kh.; Sokolova, I.N.; Vybornyy, Zh.I.

    1995-06-01

    In this report results of work on establishment of a data base of regional seismic recordings from earthquakes, chemical explosions and nuclear explosions in the former Soviet Union are described. This work was carried out in the Complex Seismological Expedition (CSE) of the Joint Institute of Physics of the Earth of the Russian Academy of Sciences and Lawrence Livermore National Laboratory. The recording system, methods of investigations and primary data processing are described in detail. The largest number of digital records was received by the permanent seismic station Talgar, situated in the northern Tien Shan, 20 km to the east of Almaty city. More than half of the records are seismograms of underground nuclear explosions and chemical explosions. The nuclear explosions were recorded mainly from the Semipalatinsk test site. In addition, records of the explosions from the Chinese test site Lop Nor and industrial nuclear explosions from the West Siberia region were obtained. Four records of strong chemical explosions were picked out (two of them have been produced at the Semipalatinsk test site and two -- in Uzbekistan). We also obtained 16 records of crustal earthquakes, mainly from the Altai region, close to the Semipalatinsk test site, and also from the West China region, close to the Lop Nor test site. In addition, a small number of records of earthquakes and underground nuclear explosions, received by arrays of temporary stations, that have been working in the southern Kazakhstan region are included in this report. Parameters of the digital seismograms and file structure are described. Possible directions of future work on the digitizing of unique data archive are discussed.

  19. Testing Galactic Cosmic Ray Models

    NASA Technical Reports Server (NTRS)

    Adams, James H., Jr.

    2009-01-01

    Models of the Galactic Cosmic Ray Environment are used for designing and planning space missions. The existing models will be reviewed. Spectral representations from these models will be compared with measurements of galactic cosmic ray spectra made on balloon flights and satellite flights over a period of more than 50 years.

  20. Testing Galactic Cosmic Ray Models

    NASA Technical Reports Server (NTRS)

    Adams, James H., Jr.

    2010-01-01

    Models of the Galactic Cosmic Ray Environment are used for designing and planning space missions. The exising models will be reviewed. Spectral representations from these models will be compared with measurements of galactic cosmic ray spectra made on balloon flights and satellite flights over a period of more than 50 years.

  1. The age of the Galactic disk - Inflow, chemical evolution, astration, and radioactivity

    NASA Technical Reports Server (NTRS)

    Clayton, Donald D.

    1989-01-01

    Theoretical models of Galactic evolution and observational data on the age of the Galaxy are compared, with a focus on recent results. Topics addressed include the infall of material and its effects on the age-metallicity relation, the distribution of metallicity, the present gas fraction and metallicity, and the age spectrum of interstellar nuclei; the chemical evolution of the solar neighborhood; the key results of nuclear cosmochronology; and astration effects on Galactic age. It is found that both nuclear cosmochronology and detailed stellar and Galactic evolution models tend to support an age of 12-16 Gyr.

  2. A PUZZLE INVOLVING GALACTIC BULGE MICROLENSING EVENTS

    SciTech Connect

    Cohen, Judith G.; Gould, Andrew; Johnson, Jennifer A.; Thompson, Ian B.; Feltzing, Sofia; Bensby, Thomas; Huang Wenjin; Melendez, Jorge; Lucatello, Sara; Asplund, Martin E-mail: gould@astronomy.ohio-state.edu E-mail: ian@obs.carnegiescience.edu E-mail: tbensby@eso.org E-mail: jorge@astro.up.pt E-mail: asplund@MPA-Garching.MPG.DE

    2010-03-01

    We study a sample of 16 microlensed Galactic bulge main-sequence turnoff region stars for which high-dispersion spectra have been obtained with detailed abundance analyses. We demonstrate that there is a very strong and highly statistically significant correlation between the maximum magnification of the microlensed bulge star and the value of the [Fe/H] deduced from the high resolution spectrum of each object. Physics demands that this correlation, assuming it to be real, be the result of some sample bias. We suggest several possible explanations, but are forced to reject them all, and are left puzzled. To obtain a reliable metallicity distribution in the Galactic bulge based on microlensed dwarf stars, it will be necessary to resolve this issue through the course of additional observations.

  3. Galactic transients from the OGLE survey

    NASA Astrophysics Data System (ADS)

    Mroz, Przemek

    2016-07-01

    For many years, there were not any systematic, large-scale surveys for transients in the Milky Way and the Magellanic Clouds. This gap is being filled by discoveries from the OGLE survey, which has been regularly monitoring the densest sky regions (the Galactic bulge and disk, the Magellanic System) for over twenty years. The OGLE collection of Galactic transients contains several dozen classical novae and over a thousand other cataclysmic variables. I will tell how to select transients from billions of sources observed by the OGLE every night. I will show how the properties of classical novae depend on the underlying stellar population (and the star formation history). I will also discuss the preliminary results of the search for transients in the Milky Way disk from the OGLE-IV Galaxy Variability Survey. Finally, I will show some transients of yet unknown origin and present the OGLE-IV real time monitoring systems.

  4. Scattered light in Galactic H II Regions

    NASA Astrophysics Data System (ADS)

    Robledo-Rella, V.

    2002-02-01

    We find that dust-scattered light is the dominant contributor (50-70%) to the continuum in the pure nebular spectra (bright stars excluded) of NGC 3372 (Carina), M8 and M20. On the other hand, the stellar spectra contributes only about 50% of the continuum when the stars are included. This high contribution of scattered light should be taken into account when deriving the age and stellar content from observed Equivalent Widths ( W[H scriptstyle beta ]) in spatially resolved GEHRs and H II galaxies.

  5. Mapping of nuclear import signal and importin {alpha}3 binding regions of 52K protein of bovine adenovirus-3

    SciTech Connect

    Paterson, Carolyn P.; Ayalew, Lisanework E.; Tikoo, Suresh K.

    2012-10-10

    The L1 region of bovine adenovirus (BAdV)-3 encodes a non-structural protein designated 52K. Anti-52K serum detected a protein of 40 kDa, which localized to the nucleus but not to the nucleolus in BAdV-3-infected or transfected cells. Analysis of mutant 52K proteins suggested that three basic residues ({sup 105}RKR{sup 107}) of the identified domain (amino acids {sup 102}GMPRKRVLT{sup 110}) are essential for nuclear localization of 52K. The nuclear import of a GST-52K fusion protein utilizes the classical importin {alpha}/{beta}-dependent nuclear transport pathway. The 52K protein is preferentially bound to the cellular nuclear import receptor importin {alpha}3. Although deletion of amino acid 102-110 is sufficient to abrogate the nuclear localization of 52K, amino acid 90-133 are required for interaction with importin-{alpha}3 and localizing a cytoplasmic protein to the nucleus. These results suggest that 52K contains a bipartite NLS, which preferentially utilize an importin {alpha}3 nuclear import receptor-mediated pathway to transport 52K to the nucleus.

  6. Diffuse Galactic low energy gamma ray continuum emission

    NASA Technical Reports Server (NTRS)

    Skibo, J. G.; Ramaty, R.

    1993-01-01

    We investigate the origin of diffuse low-energy Galactic gamma-ray continuum down to about 30 keV. We calculate gamma-ray emission via bremsstrahlung and inverse Compton scattering by propagating an unbroken electron power law injection spectrum and employing a Galactic emmissivity model derived from COSB observations. To maintain the low energy electron population capable of producing the observed continuum via bremsstrahlung, a total power input of 4 x 10 exp 41 erg/s is required. This exceeds the total power supplied to the nuclear cosmic rays by about an order of magnitude.

  7. Galactic Hearts of Glass

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Click on image for larger graph

    This artist's concept shows delicate greenish crystals sprinkled throughout the violent core of a pair of colliding galaxies. The white spots represent a thriving population of stars of all sizes and ages. NASA's Spitzer Space Telescope detected more than 20 bright and dusty galactic mergers like the one depicted here, all teeming with the tiny gem-like crystals.

    When galaxies collide, they trigger the birth of large numbers of massive stars. Astronomers believe these blazing hot stars act like furnaces to produce silicate crystals in the same way that glass is made from sand. The stars probably shed the crystals as they age, and as they blow apart in supernovae explosions.

    At the same time the crystals are being churned out, they are also being destroyed. Fast-moving particles from supernova blasts easily convert silicates crystals back to their amorphous, or shapeless, form.

    How is Spitzer seeing the crystals if they are rapidly disappearing? Astronomers say that, for a short period of time at the beginning of galactic mergers, massive stars might be producing silicate crystals faster than they are eliminating them. When our own galaxy merges with the Andromeda galaxy in a few billion years, a similar burst of massive stars and silicate crystals might occur.

    Crystal Storm in Distant Galaxy The graph (see inset above) of infrared data from NASA's Spitzer Space Telescope tells astronomers that a distant galaxy called IRAS 08752+3915 is experiencing a storm of tiny crystals made up of silicates. The crystals are similar to the glass-like grains of sand found on Earth's many beaches.

    The data were taken by Spitzer's infrared spectrograph, which splits light open to reveal its rainbow-like components. The resulting spectrum shown here reveals the signatures of both crystalline (green) and non-crystalline (brown) silicates.

    Spitzer detected the same

  8. Could wormholes form in dark matter galactic halos?

    NASA Astrophysics Data System (ADS)

    Rahaman, Farook; Shit, G. C.; Sen, Banashree; Ray, Saibal

    2016-01-01

    We estimate expression for velocity as a function of the radial coordinate r by using polynomial interpolation based on the experimental data of rotational velocities at distant outer regions of galaxies. The interpolation technique has been used to estimate fifth degree polynomial followed by cubic spline interpolation. This rotational velocity is used to find the geometry of galactic halo regions within the framework of Einstein's general relativity. In this paper we have analyzed features of galactic halo regions based on two possible choices for the dark matter density profile, viz. Navarro, Frenk & White (NFW) type (Navarro et al. in Astrophys. J. 462:563, 1996) and Universal Rotation Curve (URC) (Castignani et al. in Nat. Sci. 4:265, 2012). It is argued that spacetime of the galactic halo possesses some of the characteristics needed to support traversable wormholes.

  9. Grains in galactic haloes

    NASA Technical Reports Server (NTRS)

    Ferrara, Andrea; Barsella, Bruno; Ferrini, F.; Greenberg, J. Mayo; Aiello, Santi

    1989-01-01

    Researchers considered the effect of extensive forces on dust grains subjected to the light and matter distribution of a spiral galaxy (Greenberg et al. (1987), Ferrini et al. (1987), Barsella et al (1988). Researchers showed that the combined force on a small particle located above the plane of a galactic disk may be either attractive or repulsive depending on a variety of parameters. They found, for example, that graphite grains from 20 nm to 250 nm radius are expelled from a typical galaxy, while silicates and other forms of dielectrics, after initial expulsion, may settle in potential minimum within the halo. They discuss only the statistical behavior of the forces for 17 galaxies whose luminosity and matter distribution in the disk, bulge and halo components are reasonably well known. The preliminary results of the study of the motion of a dust grain for NGC 3198 are given.

  10. The Galactic Center

    NASA Astrophysics Data System (ADS)

    Genzel, Reinhard; Karas, Vladimír

    2007-04-01

    In the past decade high resolution measurements in the infrared employing adaptive optics imaging on 10m telescopes have allowed determining the three dimensional orbits stars within ten light hours of the compact radio source SgrA* at the Center of the Milky Way. These observations show that SgrA* is a three million solar mass black hole, beyond any reasonable doubt. The Galactic Center thus constitutes the best astrophysical evidence for the existence of black holes which have long been postulated, and is also an ideal 'lab' for studying the physics in the vicinity of such an object. Remarkably, young massive stars are present there and probably have formed in the innermost stellar cusp. Variable infrared and X-ray emission from SgrA* are a new probe of the physics and space time just outside the event horizon.

  11. Galactic Diffuse Polarized Emission

    NASA Astrophysics Data System (ADS)

    Carretti, Ettore

    2011-12-01

    Diffuse polarized emission by synchrotron is a key tool to investigate magnetic fields in the Milky Way, particularly the ordered component of the large scale structure. Key observables are the synchrotron emission itself and the RM is by Faraday rotation. In this paper the main properties of the radio polarized diffuse emission and its use to investigate magnetic fields will be reviewed along with our current understanding of the galactic magnetic field and the data sets available. We will then focus on the future perspective discussing RM-synthesis - the new powerful instrument devised to unlock the information encoded in such an emission - and the surveys currently in progress like S-PASS and GMIMS.

  12. Study of galactic light, extragalactic light, and galactic structure using pioneer 10 observations of background starlight

    SciTech Connect

    Toller, G.N.

    1981-01-01

    An observational and theoretical study of the diffuse astronomical background sky brightness (background starlight) is carried out. The brightness is determined over 95% of the sky using Pioneer 10 photometric measurements in sky regions where the zodiacal light is negligible (heliocentric distances approx. greater than or equal to 3. A.U.). Brightness levels are presented at blue (3950 to 4850 A) and red (5900 to 6800 A) wavelengths. The B-R color index distribution is established over the celestial sphere. Pioneer 10 results are compared with previous star count and ground based photometric studies to separate background starlight into its constituent parts: integrated starlight, diffuse galactic light (DGL), and cosmic light. Significant errors are found in published star count results at low galactic latitudes. The galactic latitude (b'') and longitude (1'') dependences of integrated starlight and the variation of DGL with b'' are determined. An upper limit of 3.9 S/sub 10/(V)/sub G2V/ at the 90% confidence level is deduced for the cosmic light brightness at blue wavelengths near the galactic poles. The integrated light from discrete galaxies adequately explains this component of the background starlight.

  13. Basic amino acid residues located in the N-terminal region of BEND3 are essential for its nuclear localization.

    PubMed

    Shiheido, Hirokazu; Shimizu, Jun

    2015-02-20

    BEN domain-containing protein 3 (BEND3) has recently been reported to function as a heterochromatin-associated protein in transcriptional repression in the nucleus. BEND3 should have nuclear localization signals (NLSs) to localize to the nucleus in light of its molecular weight, which is higher than that allowed to pass through nuclear pore complexes. We here analyzed the subcellular localization of deletion/site-directed mutants of human BEND3 by an immunofluorescence assay in an attempt to identify the amino acids essential for its nuclear localization. We found that three basic amino acid residues located in the N-terminal region of BEND3 (BEND356-58, KRK) are essential, suggesting that these residues play a role as a functional NLS. These results provide valuable information for progressing research on BEND3.

  14. Basic amino acid residues located in the N-terminal region of BEND3 are essential for its nuclear localization.

    PubMed

    Shiheido, Hirokazu; Shimizu, Jun

    2015-02-20

    BEN domain-containing protein 3 (BEND3) has recently been reported to function as a heterochromatin-associated protein in transcriptional repression in the nucleus. BEND3 should have nuclear localization signals (NLSs) to localize to the nucleus in light of its molecular weight, which is higher than that allowed to pass through nuclear pore complexes. We here analyzed the subcellular localization of deletion/site-directed mutants of human BEND3 by an immunofluorescence assay in an attempt to identify the amino acids essential for its nuclear localization. We found that three basic amino acid residues located in the N-terminal region of BEND3 (BEND356-58, KRK) are essential, suggesting that these residues play a role as a functional NLS. These results provide valuable information for progressing research on BEND3. PMID:25600804

  15. Acceleration of petaelectronvolt protons in the Galactic Centre

    NASA Astrophysics Data System (ADS)

    HESS Collaboration; Abramowski, A.; Aharonian, F.; Benkhali, F. Ait; Akhperjanian, A. G.; Angüner, E. O.; Backes, M.; Balzer, A.; Becherini, Y.; Tjus, J. Becker; Berge, D.; Bernhard, S.; Bernlöhr, K.; Birsin, E.; Blackwell, R.; Böttcher, M.; Boisson, C.; Bolmont, J.; Bordas, P.; Bregeon, J.; Brun, F.; Brun, P.; Bryan, M.; Bulik, T.; Carr, J.; Casanova, S.; Chakraborty, N.; Chalme-Calvet, R.; Chaves, R. C. G.; Chen, A.; Chrétien, M.; Colafrancesco, S.; Cologna, G.; Conrad, J.; Couturier, C.; Cui, Y.; Davids, I. D.; Degrange, B.; Deil, C.; Dewilt, P.; Djannati-Ataï, A.; Domainko, W.; Donath, A.; Drury, L. O'C.; Dubus, G.; Dutson, K.; Dyks, J.; Dyrda, M.; Edwards, T.; Egberts, K.; Eger, P.; Ernenwein, J.-P.; Espigat, P.; Farnier, C.; Fegan, S.; Feinstein, F.; Fernandes, M. V.; Fernandez, D.; Fiasson, A.; Fontaine, G.; Förster, A.; Füßling, M.; Gabici, S.; Gajdus, M.; Gallant, Y. A.; Garrigoux, T.; Giavitto, G.; Giebels, B.; Glicenstein, J. F.; Gottschall, D.; Goyal, A.; Grondin, M.-H.; Grudzińska, M.; Hadasch, D.; Häffner, S.; Hahn, J.; Hawkes, J.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hervet, O.; Hillert, A.; Hinton, J. A.; Hofmann, W.; Hofverberg, P.; Hoischen, C.; Holler, M.; Horns, D.; Ivascenko, A.; Jacholkowska, A.; Jamrozy, M.; Janiak, M.; Jankowsky, F.; Jung-Richardt, I.; Kastendieck, M. A.; Katarzyński, K.; Katz, U.; Kerszberg, D.; Khélifi, B.; Kieffer, M.; Klepser, S.; Klochkov, D.; Kluźniak, W.; Kolitzus, D.; Komin, Nu.; Kosack, K.; Krakau, S.; Krayzel, F.; Krüger, P. P.; Laffon, H.; Lamanna, G.; Lau, J.; Lefaucheur, J.; Lefranc, V.; Lemiére, A.; Lemoine-Goumard, M.; Lenain, J.-P.; Lohse, T.; Lopatin, A.; Lu, C.-C.; Lui, R.; Marandon, V.; Marcowith, A.; Mariaud, C.; Marx, R.; Maurin, G.; Maxted, N.; Mayer, M.; Meintjes, P. J.; Menzler, U.; Meyer, M.; Mitchell, A. M. W.; Moderski, R.; Mohamed, M.; Morå, K.; Moulin, E.; Murach, T.; de Naurois, M.; Niemiec, J.; Oakes, L.; Odaka, H.; Öttl, S.; Ohm, S.; Opitz, B.; Ostrowski, M.; Oya, I.; Panter, M.; Parsons, R. D.; Arribas, M. Paz; Pekeur, N. W.; Pelletier, G.; Petrucci, P.-O.; Peyaud, B.; Pita, S.; Poon, H.; Prokoph, H.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raab, S.; Reichardt, I.; Reimer, A.; Reimer, O.; Renaud, M.; de Los Reyes, R.; Rieger, F.; Romoli, C.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Sahakian, V.; Salek, D.; Sanchez, D. A.; Santangelo, A.; Sasaki, M.; Schlickeiser, R.; Schüssler, F.; Schulz, A.; Schwanke, U.; Schwemmer, S.; Seyffert, A. S.; Simoni, R.; Sol, H.; Spanier, F.; Spengler, G.; Spies, F.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Stycz, K.; Sushch, I.; Tavernet, J.-P.; Tavernier, T.; Taylor, A. M.; Terrier, R.; Tluczykont, M.; Trichard, C.; Tuffs, R.; Valerius, K.; van der Walt, J.; van Eldik, C.; van Soelen, B.; Vasileiadis, G.; Veh, J.; Venter, C.; Viana, A.; Vincent, P.; Vink, J.; Voisin, F.; Völk, H. J.; Vuillaume, T.; Wagner, S. J.; Wagner, P.; Wagner, R. M.; Weidinger, M.; Weitzel, Q.; White, R.; Wierzcholska, A.; Willmann, P.; Wörnlein, A.; Wouters, D.; Yang, R.; Zabalza, V.; Zaborov, D.; Zacharias, M.; Zdziarski, A. A.; Zech, A.; Zefi, F.; Żywucka, N.

    2016-03-01

    Galactic cosmic rays reach energies of at least a few petaelectronvolts (of the order of 1015 electronvolts). This implies that our Galaxy contains petaelectronvolt accelerators (‘PeVatrons’), but all proposed models of Galactic cosmic-ray accelerators encounter difficulties at exactly these energies. Dozens of Galactic accelerators capable of accelerating particles to energies of tens of teraelectronvolts (of the order of 1013 electronvolts) were inferred from recent γ-ray observations. However, none of the currently known accelerators—not even the handful of shell-type supernova remnants commonly believed to supply most Galactic cosmic rays—has shown the characteristic tracers of petaelectronvolt particles, namely, power-law spectra of γ-rays extending without a cut-off or a spectral break to tens of teraelectronvolts. Here we report deep γ-ray observations with arcminute angular resolution of the region surrounding the Galactic Centre, which show the expected tracer of the presence of petaelectronvolt protons within the central 10 parsecs of the Galaxy. We propose that the supermassive black hole Sagittarius A* is linked to this PeVatron. Sagittarius A* went through active phases in the past, as demonstrated by X-ray outburstsand an outflow from the Galactic Centre. Although its current rate of particle acceleration is not sufficient to provide a substantial contribution to Galactic cosmic rays, Sagittarius A* could have plausibly been more active over the last 106-107 years, and therefore should be considered as a viable alternative to supernova remnants as a source of petaelectronvolt Galactic cosmic rays.

  16. Acceleration of petaelectronvolt protons in the Galactic Centre.

    PubMed

    2016-03-24

    Galactic cosmic rays reach energies of at least a few petaelectronvolts (of the order of 10(15) electronvolts). This implies that our Galaxy contains petaelectronvolt accelerators ('PeVatrons'), but all proposed models of Galactic cosmic-ray accelerators encounter difficulties at exactly these energies. Dozens of Galactic accelerators capable of accelerating particles to energies of tens of teraelectronvolts (of the order of 10(13) electronvolts) were inferred from recent γ-ray observations. However, none of the currently known accelerators--not even the handful of shell-type supernova remnants commonly believed to supply most Galactic cosmic rays--has shown the characteristic tracers of petaelectronvolt particles, namely, power-law spectra of γ-rays extending without a cut-off or a spectral break to tens of teraelectronvolts. Here we report deep γ-ray observations with arcminute angular resolution of the region surrounding the Galactic Centre, which show the expected tracer of the presence of petaelectronvolt protons within the central 10 parsecs of the Galaxy. We propose that the supermassive black hole Sagittarius A* is linked to this PeVatron. Sagittarius A* went through active phases in the past, as demonstrated by X-ray outburstsand an outflow from the Galactic Centre. Although its current rate of particle acceleration is not sufficient to provide a substantial contribution to Galactic cosmic rays, Sagittarius A* could have plausibly been more active over the last 10(6)-10(7) years, and therefore should be considered as a viable alternative to supernova remnants as a source of petaelectronvolt Galactic cosmic rays.

  17. Acceleration of petaelectronvolt protons in the Galactic Centre.

    PubMed

    2016-03-24

    Galactic cosmic rays reach energies of at least a few petaelectronvolts (of the order of 10(15) electronvolts). This implies that our Galaxy contains petaelectronvolt accelerators ('PeVatrons'), but all proposed models of Galactic cosmic-ray accelerators encounter difficulties at exactly these energies. Dozens of Galactic accelerators capable of accelerating particles to energies of tens of teraelectronvolts (of the order of 10(13) electronvolts) were inferred from recent γ-ray observations. However, none of the currently known accelerators--not even the handful of shell-type supernova remnants commonly believed to supply most Galactic cosmic rays--has shown the characteristic tracers of petaelectronvolt particles, namely, power-law spectra of γ-rays extending without a cut-off or a spectral break to tens of teraelectronvolts. Here we report deep γ-ray observations with arcminute angular resolution of the region surrounding the Galactic Centre, which show the expected tracer of the presence of petaelectronvolt protons within the central 10 parsecs of the Galaxy. We propose that the supermassive black hole Sagittarius A* is linked to this PeVatron. Sagittarius A* went through active phases in the past, as demonstrated by X-ray outburstsand an outflow from the Galactic Centre. Although its current rate of particle acceleration is not sufficient to provide a substantial contribution to Galactic cosmic rays, Sagittarius A* could have plausibly been more active over the last 10(6)-10(7) years, and therefore should be considered as a viable alternative to supernova remnants as a source of petaelectronvolt Galactic cosmic rays. PMID:26982725

  18. Functional analysis of the C-terminal region of human adenovirus E1A reveals a misidentified nuclear localization signal

    SciTech Connect

    Cohen, Michael J.; King, Cason R.; Dikeakos, Jimmy D.; Mymryk, Joe S.

    2014-11-15

    The immortalizing function of the human adenovirus 5 E1A oncoprotein requires efficient localization to the nucleus. In 1987, a consensus monopartite nuclear localization sequence (NLS) was identified at the C-terminus of E1A. Since that time, various experiments have suggested that other regions of E1A influence nuclear import. In addition, a novel bipartite NLS was recently predicted at the C-terminal region of E1A in silico. In this study, we used immunofluorescence microscopy and co-immunoprecipitation analysis with importin-α to verify that full nuclear localization of E1A requires the well characterized NLS spanning residues 285–289, as well as a second basic patch situated between residues 258 and 263 ({sup 258}RVGGRRQAVECIEDLLNEPGQPLDLSCKRPRP{sup 289}). Thus, the originally described NLS located at the C-terminus of E1A is actually a bipartite signal, which had been misidentified in the existing literature as a monopartite signal, altering our understanding of one of the oldest documented NLSs. - Highlights: • Human adenovirus E1A is localized to the nucleus. • The C-terminus of E1A contains a bipartite nuclear localization signal (NLS). • This signal was previously misidentified to be a monopartite NLS. • Key basic amino acid residues within this sequence are highly conserved.

  19. Phylogeny of Populus (Salicaceae) based on nucleotide sequences of chloroplast TRNT-TRNF region and nuclear rDNA.

    PubMed

    Hamzeh, Mona; Dayanandan, Selvadurai

    2004-09-01

    The species of the genus Populus, collectively known as poplars, are widely distributed over the northern hemisphere and well known for their ecological, economical, and evolutionary importance. The extensive interspecific hybridization and high morphological diversity in this group pose difficulties in identifying taxonomic units for comparative evolutionary studies and systematics. To understand the evolutionary relationships among poplars and to provide a framework for biosystematic classification, we reconstructed a phylogeny of the genus Populus based on nucleotide sequences of three noncoding regions of the chloroplast DNA (intron of trnL and intergenic regions of trnT-trnL and trnL-trnF) and ITS1 and ITS2 of the nuclear rDNA. The resulting phylogenetic trees showed polyphyletic relationships among species in the sections Tacamahaca and Aigeiros. Based on chloroplast DNA sequence data, P. nigra had a close affinity to species of section Populus, whereas nuclear DNA sequence data suggested a close relationship between P. nigra and species of the section Aigeiros, suggesting a possible hybrid origin for P. nigra. Similarly, the chloroplast DNA sequences of P. tristis and P. szechuanica were similar to that of the species of section Aigeiros, while the nuclear sequences revealed a close affinity to species of the section Tacamahaca, suggesting a hybrid origin for these two Asiatic balsam poplars. The incongruence between phylogenetic trees based on nuclear- and chloroplast-DNA sequence data suggests a reticulate evolution in the genus Populus.

  20. The nuclear regions of NGC 3311 and NGC 7768 imaged with the Hubble Space Telescope Planetary Camera

    NASA Technical Reports Server (NTRS)

    Grillmair, Carl J.; Faber, S.M.; Lauer, Tod R.; Baum, William A.; Lynds, Roger C.; O'Neil, Earl J., Jr.; Shaya, Edward J.

    1994-01-01

    We present high-resolution, V band images of the central regions of the brightest cluster ellipticals NGC 3311 and NGC 7768 taken with the Planetary Camera of the Hubble Space Telescope. The nuclei of both galaxies are found to be obscured by dust, though the morphology of the dust is quite different in the two cases. The dust cloud which obscures the central 3 arcsec of NGC 3311 is complex and irregular, while the central region of NGC 7768 contains a disk of material similar in appearance and scale to that recently observed in HST images of NGC 4261. The bright, relatively blue source detected in ground-based studies of NGC 3311 is marginally resolved and is likely to be a site of ongoing star formation. We examine the distribution of globular clusters in the central regions of NGC 3311. The gradient in the surface density profile of the cluster system is significantly shallower than that found by previous investigators at larger radii. We find a core radius for the cluster distribution of 12 plus or minus 3 kpc, which is even larger than the core radius of the globular cluster system surrounding M87. It is also an order of magnitude larger than the upper limit on the core radius of NGC 3311's stellar light and suggests that the central field-star population and the globular cluster system are dynamically distinct. We briefly discuss possible sources for the cold/warm interstellar material in early-type galaxies. While the issue has not been resolved, models which involve galactic wind failure appear to be mo st naturally consistent with the observations.

  1. Nuclear dependence of structure functions in the shadowing region of deep inelastic scattering

    SciTech Connect

    Berger, E.L.; Qiu, Jianwei

    1988-07-27

    A discussion of nuclear shadowing in deep inelastic lepton scattering is presented. We show that the parton recombination model suggests that shadowing should begin to occur at larger values of Bjorken x as A increases. This expectation as well as that of weak dependence on Q/sup 2/, and the trend of the x dependence of the shadowing phenomenon are consistent with recent data. Shadowing at small x is combined with nuclear bound state effects, responsible for nuclear dependence at larger x, to provide description of the A dependence of the structure function for the entire range of x. 21 refs., 5 figs.

  2. The galactic globular cluster system

    NASA Technical Reports Server (NTRS)

    Djorgovski, S.; Meylan, G.

    1994-01-01

    We explore correlations between various properties of Galactic globular clusters, using a database on 143 objects. Our goal is identify correlations and trends which can be used to test and constrain theoretical models of cluster formation and evolution. We use a set of 13 cluster parameters, 9 of which are independently measured. Several arguments suggest that the number of clusters still missing in the obscured regions of the Galaxy is of the order of 10, and thus the selection effects are probably not severe for our sample. Known clusters follow a power-law density distribution with a slope approximately -3.5 to -4, and an apparent core with a core radius approximately 1 kpc. Clusters show a large dynamical range in many of their properties, more so for the core parameters (which are presumably more affected by dynamical evolution) than for the half-light parameters. There are no good correlations with luminosity, although more luminous clusters tend to be more concentrated. When data are binned in luminosity, several trends emerge: more luminous clusters tend to have smaller and denser cores. We interpret this as a differential survival effect, with more massive clusters surviving longer and reaching more evolved dynamical states. Cluster core parameters and concentrations also correlate with the position in the Galaxy, with clusters closer to the Galactic center or plane being more concentrated and having smaller and denser cores. These trends are more pronounced for the fainter (less massive) clusters. This is in agreement with a picture where tidal shocks form disk or bulge passages accelerate dynamical evolution of clusters. Cluster metallicities do not correlate with any other parameter, including luminosity and velocity dispersion; the only detectable trend is with the position in the Galaxy, probably reflecting Zinn's disk-halo dichotomy. This suggests that globular clusters were not self-enriched systems. Velocity dispersions show excellent correlations

  3. Hyperdeformation in the cranked relativistic mean field theory: The Z=40-58 region of the nuclear chart

    SciTech Connect

    Afanasjev, A. V.; Abusara, H.

    2008-07-15

    The systematic investigation of hyperdeformation (HD) at high spin in the Z=40-58 region of the nuclear chart was performed in the framework of the cranked relativistic mean-field theory. The properties of the moments of inertia of the HD bands, the role of the single-particle and necking degrees of freedom at HD, the spins at which the HD bands become yrast, the possibility to observe discrete HD bands, and so on are discussed in detail.

  4. Imprints to the terrestrial environment at galactic arm crossings of the solar system

    NASA Astrophysics Data System (ADS)

    Fahr, H. J.; Fichtner, H.; Scherer, K.; Stawicki, O.

    At its itinerary through our milky way galaxy the solar system moves through highly variable interstellar environments. Due to its orbital revolution around the galactic center, the solar system also crosses periodically the spiral arms of our galactic plane and thereby expe riences pronounced enviromental changes. Gas densities, magnetic fields and galactic cosmic ray intensities are substantially higher there compared to interarm conditions. Here we present theoretical calculations describing the SN-averaged galactic cosmic ray spectrum for regions inside and outside of galactic arms which then allow to predict how periodic passages of the solar system through galactic arms should be reflected by enhanced particle irradiations of the earth`s atmosphere and by correlated terrestrial Be-10 production rates.

  5. VERITAS Observations of The Galactic Center Ridge

    NASA Astrophysics Data System (ADS)

    Smith, Andrew W

    2014-08-01

    The Galactic Center Ridge is perhaps the most local, busy environment for high-energy particle acceleration, harboring as it does many relativistic particle accelerators such as pulsar wind nebulae, supernova remnants, and the central supermassive black hole SgrA*. Observations with very high energy (VHE, >100 GeV) gamma-ray telescopes of the region have revealed multiple point sources associated with well-known objects, as well as regions of extended emission not directly associated with sources at other wavelengths. More importantly, the detection of a large, diffuse component of >300 GeV gamma-ray emission by the HESS collaboration is strongly believed to be the result of accelerated cosmic rays interacting with molecular-cloud regions, thus providing insight into high-energy cosmic ray acceleration. Here we present the VERITAS observations of the Galactic Center Ridge taken from 2008-2014 in the >2 TeV regime. We will focus on the VERITAS results on the known HESS sources in the region, as well as the diffuse component of TeV emission along the plane. Due to the much higher energy threshold of the VERITAS observations, our data provide a new window into some of the highest energy particle acceleration occurring in the center of our galaxy.

  6. VERITAS Observations of The Galactic Center Ridge

    NASA Astrophysics Data System (ADS)

    Smith, Andrew; Veritas

    2015-01-01

    The Galactic Center Ridge is perhaps the most local, busy environment for high energy particle acceleration; home to many relativistic particle accelerators such as pulsar wind nebulae, supernova remnants, and the central supermassive black hole SgrA*. Observations with VHE (>100 GeV) gamma-ray telescopes of the region have revealed multiple point sources associated with well known objects, as well as regions of extended emission not directly associated with targets at other wavelengths. More importantly, the detection of a large, diffuse component of >300 GeV gamma-ray emission by the HESS collaboration is strongly believed to be the result of accelerated cosmic rays interacting with molecular cloud regions, thus providing a window into high energy cosmic ray acceleration. Here we present the VERITAS observations of the Galactic Center Ridge taken from 2008-2014 in the >2 TeV regime. We will focus on the VERITAS results on the known HESS sources in the region, as well as the diffuse component of TeV emission along the plane. Due to the much higher energy threshold of the VERITAS observations, our data provide a new window into some of the highest energy particle acceleration occurring in the center of our galaxy.

  7. Production and dissolution of nuclear explosive melt glasses at underground test sites in the Pacific Region

    SciTech Connect

    Bourcier, W.L.; Smith, D.K.

    1998-11-06

    From 1975 to 1996 the French detonated 140 underground nuclear explosions beneath the atolls of Mururoa and Fangataufa in the South Pacific; from 1965 to 1971 the United States detonated three high yield nuclear tests beneath Amchitka Island in the Aleutian chain. Approximately 800 metric tons of basalt is melted per kiloton of nuclear yield; almost lo7 metric tons of basalt were melted in these tests. Long-lived and toxic radionuclides are partitioned into the melt glass at the time of explosion and are released by dissolution with seawater under saturated conditions. A glass dissolution model predicts that nuclear melt glasses at these sites will dissolve in lo6 to lo7 yea

  8. Nuclear structure and decay properties of even-even nuclei in Z = 70-80 drip-line region

    NASA Astrophysics Data System (ADS)

    Mahapatro, S.; Lahiri, C.; Kumar, Bharat; Mishra, R. N.; Patra, S. K.

    2016-08-01

    We study nuclear structure properties for various isotopes of Ytterbium (Yb), Hafnium(Hf), Tungsten(W), Osmium(Os), Platinum(Pt) and Mercury(Hg) in Z = 70-80 drip-line region starting from N = 80 to N = 170 within the formalism of relativistic mean field (RMF) theory. The pairing correlation is taken care by using BCS approach. We compared our results with finite range droplet model(FRDM) and experimental data and found that the calculated results are in good agreement. Neutron shell closure is obtained at N = 82 and 126 in this region. We have also studied probable decay mechanisms of these elements.

  9. Modeled Neutron Induced Nuclear Reaction Cross Sections for Radiochemistry in the region of Iriduim and Gold

    SciTech Connect

    Hoffman, R D; Dietrich, F S; Kelley, K; Escher, J; Bauer, R; Mustafa, M

    2008-02-26

    We have developed a set of modeled nuclear reaction cross sections for use in radiochemical diagnostics. Systematics for the input parameters required by the Hauser-Feshbach statistical model were developed and used to calculate neutron induced nuclear reaction cross sections for targets ranging from osmium (Z = 76) to gold (Z = 79). Of particular interest are the cross sections on Ir and Au including reactions on isomeric targets.

  10. VizieR Online Data Catalog: Compact radio sources near Galactic center (Pynzar'+, 2014)

    NASA Astrophysics Data System (ADS)

    Pynzar', A. V.; Shishov, V. I.

    2014-07-01

    Using literature data on approximately 400 compact radio sources detected with the Very Large Array and located in the direction of the Galactic center within 2° of the compact source Sgr A*, 69 sources whose angular sizes are determined by scattering on electron density inhomogeneities were distinguished. Fifty-five of these are extragalactic, two are supercompact HII regions, ten are sources of maser emission, and two are variable Galactic sources. The excess of the apparent angular sizes of maser sources within 2° of the Galactic center above the mean size of objects of this class in other parts of the Galaxy found in many studies cannot be explained purely by the effect of scattering of their radio emission on interstellar plasma inhomogeneities. The angular sizes of these objects are increased due to scattering only within Galactic longitudes of about 0.4° and Galactic latitudes less than 0.1°. The turbulent medium responsible for scattering of radio emission of compact sources in the immediate vicinity of the Galactic center is strongly concentrated toward the compact source Sgr A* at the Galactic center. No extragalactic sources are observed within 0.4° in longitude and 0.2° in latitude of the Galactic center, because of their low brightness due to the superstrong scattering in this region. Data on scatter broadening can be used to study the distribution of turbulent plasma near the Galactic center. (3 data files).

  11. Starburst clusters in the Galactic center

    NASA Astrophysics Data System (ADS)

    Habibi, Maryam

    2014-09-01

    The central region of the Galaxy is the most active site of star formation in the Milky Way, where massive stars have formed very recently and are still forming today. The rich population of massive stars in the Galactic center provide a unique opportunity to study massive stars in their birth environment and probe their initial mass function, which is the spectrum of stellar masses at their birth. The Arches cluster is the youngest among the three massive clusters in the Galactic center, providing a collection of high-mass stars and a very dense core which makes this cluster an excellent site to address questions about massive star formation, the stellar mass function and the dynamical evolution of massive clusters in the Galactic center. In this thesis, I perform an observational study of the Arches cluster using K_{s}-band imaging obtained with NAOS/CONICA at the VLT combined with Subaru/Cisco J-band data to gain a full understanding of the cluster mass distribution out to its tidal radius for the first time. Since the light from the Galactic center reaches us through the Galactic disc, the extinction correction is crucial when studying this region. I use a Bayesian method to construct a realistic extinction map of the cluster. It is shown in this study that the determination of the mass of the most massive star in the Arches cluster, which had been used in previous studies to establish an upper mass limit for the star formation process in the Milky Way, strongly depends on the assumed slope of the extinction law. Assuming the two regimes of widely used infrared extinction laws, I show that the difference can reach up to 30% for individually derived stellar masses and Δ A_{Ks}˜ 1 magnitude in acquired K_{s}-band extinction, while the present-day mass function slope changes by ˜ 0.17 dex. The present-day mass function slope derived assuming the more recent extinction law, which suggests a steeper wavelength dependence for the infrared extinction law, reveals

  12. Spiral Galactic Formation and Evolution

    NASA Astrophysics Data System (ADS)

    Brekke, Stewart

    2009-05-01

    Before the period of galactic formation the uiverse consisted of a vast number of pre-formed systems consisting of two or more pre-galactic arms, the arms orbiting each other. As the orbits of the arms decayed the sides of the fore-sections of the arms tangentially collided and joined and thereby forming multi-armed spiral galaxies which began to rotate.The rotation resulted from the conversion of the orbital motion of the individual arms when joined into faster rotational motion of the newly formed galaxy. The spiral arms were maintained by the centripital force of the rapidly rotational motion of the galaxy system. As the rotational motion of the galaxy slowed down the arms of the spiral galaxy collapsed towards the body of the galaxy due to lessening of centripetal force on the arms and elliptical galaxies were formed and with further lessening of galactic rotational motion galactic disks were formed. One can see in galaxies M51, M100, NGC2336 and NGC4939 the galactic arms came from external orbit, not disks or instabilities in support of this theory. Also in support of this theory of galactic evolution is that spiral galaxies rotate faster than ellipticals or disks.

  13. Galactic planetary science.

    PubMed

    Tinetti, Giovanna

    2014-04-28

    Planetary science beyond the boundaries of our Solar System is today in its infancy. Until a couple of decades ago, the detailed investigation of the planetary properties was restricted to objects orbiting inside the Kuiper Belt. Today, we cannot ignore that the number of known planets has increased by two orders of magnitude nor that these planets resemble anything but the objects present in our own Solar System. Whether this fact is the result of a selection bias induced by the kind of techniques used to discover new planets--mainly radial velocity and transit--or simply the proof that the Solar System is a rarity in the Milky Way, we do not know yet. What is clear, though, is that the Solar System has failed to be the paradigm not only in our Galaxy but even 'just' in the solar neighbourhood. This finding, although unsettling, forces us to reconsider our knowledge of planets under a different light and perhaps question a few of the theoretical pillars on which we base our current 'understanding'. The next decade will be critical to advance in what we should perhaps call Galactic planetary science. In this paper, I review highlights and pitfalls of our current knowledge of this topic and elaborate on how this knowledge might arguably evolve in the next decade. More critically, I identify what should be the mandatory scientific and technical steps to be taken in this fascinating journey of remote exploration of planets in our Galaxy.

  14. Galactic planetary science

    PubMed Central

    Tinetti, Giovanna

    2014-01-01

    Planetary science beyond the boundaries of our Solar System is today in its infancy. Until a couple of decades ago, the detailed investigation of the planetary properties was restricted to objects orbiting inside the Kuiper Belt. Today, we cannot ignore that the number of known planets has increased by two orders of magnitude nor that these planets resemble anything but the objects present in our own Solar System. Whether this fact is the result of a selection bias induced by the kind of techniques used to discover new planets—mainly radial velocity and transit—or simply the proof that the Solar System is a rarity in the Milky Way, we do not know yet. What is clear, though, is that the Solar System has failed to be the paradigm not only in our Galaxy but even ‘just’ in the solar neighbourhood. This finding, although unsettling, forces us to reconsider our knowledge of planets under a different light and perhaps question a few of the theoretical pillars on which we base our current ‘understanding’. The next decade will be critical to advance in what we should perhaps call Galactic planetary science. In this paper, I review highlights and pitfalls of our current knowledge of this topic and elaborate on how this knowledge might arguably evolve in the next decade. More critically, I identify what should be the mandatory scientific and technical steps to be taken in this fascinating journey of remote exploration of planets in our Galaxy. PMID:24664916

  15. Galactic planetary science.

    PubMed

    Tinetti, Giovanna

    2014-04-28

    Planetary science beyond the boundaries of our Solar System is today in its infancy. Until a couple of decades ago, the detailed investigation of the planetary properties was restricted to objects orbiting inside the Kuiper Belt. Today, we cannot ignore that the number of known planets has increased by two orders of magnitude nor that these planets resemble anything but the objects present in our own Solar System. Whether this fact is the result of a selection bias induced by the kind of techniques used to discover new planets--mainly radial velocity and transit--or simply the proof that the Solar System is a rarity in the Milky Way, we do not know yet. What is clear, though, is that the Solar System has failed to be the paradigm not only in our Galaxy but even 'just' in the solar neighbourhood. This finding, although unsettling, forces us to reconsider our knowledge of planets under a different light and perhaps question a few of the theoretical pillars on which we base our current 'understanding'. The next decade will be critical to advance in what we should perhaps call Galactic planetary science. In this paper, I review highlights and pitfalls of our current knowledge of this topic and elaborate on how this knowledge might arguably evolve in the next decade. More critically, I identify what should be the mandatory scientific and technical steps to be taken in this fascinating journey of remote exploration of planets in our Galaxy. PMID:24664916

  16. Discovery of RR Lyrae Stars in the Nuclear Bulge of the Milky Way

    NASA Astrophysics Data System (ADS)

    Minniti, Dante; Contreras Ramos, Rodrigo; Zoccali, Manuela; Rejkuba, Marina; Gonzalez, Oscar A.; Valenti, Elena; Gran, Felipe

    2016-10-01

    Galactic nuclei, such as that of the Milky Way, are extreme regions with high stellar densities, and in most cases, the hosts of a supermassive black hole. One of the scenarios proposed for the formation of the Galactic nucleus is merging of primordial globular clusters. An implication of this model is that this region should host stars that are characteristically found in old Milky Way globular clusters. RR Lyrae stars are primary distance indicators, well known representatives of old and metal-poor stellar populations, and therefore are regularly found in globular clusters. Here we report the discovery of a dozen RR Lyrae type ab stars in the vicinity of the Galactic center, i.e., in the so-called nuclear stellar bulge of the Milky Way. This discovery provides the first direct observational evidence that the Galactic nuclear stellar bulge contains ancient stars (>10 Gyr old). Based on this we conclude that merging globular clusters likely contributed to the build-up of the high stellar density in the nuclear stellar bulge of the Milky Way.

  17. Lessons Learned from the Fukushima Nuclear Accident due to Tohoku Region Pacific Coast Earthquake

    NASA Astrophysics Data System (ADS)

    Miki, M.; Wada, M.; Takeuchi, N.

    2012-01-01

    On March 11 2011, Great Eastern Japan Earthquake hit Japan and caused the devastating damage. Fukushima Nuclear Power Station (NPS) also suffered damages and provided the environmental effect with radioactive products. The situation has been settled to some extent about two months after the accidents, and currently, the cooling of reactor is continuing towards settling the situation. Japanese NPSs are designed based on safety requirements and have multiple-folds of hazard controls. However, according to publicly available information, due to the lager-than-anticipated Tsunami, all the power supply were lost, which resulted in loss of hazard controls. Also, although nuclear power plants are equipped with system/procedure in case of loss of all controls, recovery was not made as planned in Fukushima NPSs because assumptions for hazard controls became impractical or found insufficient. In consequence, a state of emergency was declared. Through this accident, many lessons learned have been obtained from the several perspectives. There are many commonality between nuclear safety and space safety. Both industries perform thorough hazard assessments because hazards in both industries can result in loss of life. Therefore, space industry must learn from this accident and reconsider more robust space safety. This paper will introduce lessons learned from Fukushima nuclear accident described in the "Report of the Japanese Government to the IAEA Ministerial Conference on Nuclear Safety" [1], and discuss the considerations to establish more robust safety in the space systems. Detailed information of Fukushima Dai-ichi NPS are referred to this report.

  18. Integral field spectroscopy of the circum-nuclear region of the radio Galaxy Pictor A

    NASA Astrophysics Data System (ADS)

    Couto, Guilherme S.; Storchi-Bergmann, Thaisa; Robinson, Andrew; Riffel, Rogemar A.; Kharb, Preeti; Lena, Davide; Schnorr-Müller, Allan

    2016-05-01

    We present optical integral field spectroscopy of the inner 2.5 × 3.4 kpc2 of the broad-line radio galaxy Pictor A, at a spatial resolution of ≈400 pc. Line emission is observed over the whole field of view, being strongest at the nucleus and in an elongated linear feature (ELF) crossing the nucleus from the south-west to the north-east along PA ≈70°. Although the broad double-peaked Hα line and the [O I]6300/Hα and [S II]6717+31/Hα ratios are typical of active galactic nuclei (AGNs), the [N II]6584/Hα ratio (0.15-0.25) is unusually low. We suggest that this is due to the unusually low metallicity of the gas. Centroid velocity maps show mostly blueshifts to the south and redshifts to the north of the nucleus, but the velocity field is not well fitted by a rotation model. Velocity dispersions are low (<100 km s- 1 ) along the ELF, ruling out a jet-cloud interaction as the origin of this structure. The ELF shows both blueshifts and redshifts in channel maps, suggesting that it is close to the plane of the sky. The ELF is evidently photoionized by the AGN, but its kinematics and inferred low metallicity suggest that this structure may have originated in a past merger event with another galaxy. We suggest that the gas acquired in this interaction may be feeding the ELF.

  19. KINEMATICS OF CLASSICAL CEPHEIDS IN THE NUCLEAR STELLAR DISK

    SciTech Connect

    Matsunaga, Noriyuki; Fukue, Kei; Yamamoto, Ryo; Kobayashi, Naoto; Hamano, Satoshi; Inno, Laura; Genovali, Katia; Bono, Giuseppe; Baba, Junichi; Fujii, Michiko S.; Aoki, Wako; Tsujimoto, Takuji; Kondo, Sohei; Ikeda, Yuji; Nishiyama, Shogo; Nagata, Tetsuya

    2015-01-20

    Classical Cepheids are useful tracers of the Galactic young stellar population because their distances and ages can be determined from their period-luminosity and period-age relations. In addition, the radial velocities and chemical abundance of the Cepheids can be derived from spectroscopic observations, providing further insights into the structure and evolution of the Galaxy. Here, we report the radial velocities of classical Cepheids near the Galactic center, three of which were reported in 2011 and a fourth being reported for the first time. The velocities of these Cepheids suggest that the stars orbit within the nuclear stellar disk, a group of stars and interstellar matter occupying a region of ∼200 pc around the center, although the three-dimensional velocities cannot be determined until the proper motions are known. According to our simulation, these four Cepheids formed within the nuclear stellar disk like younger stars and stellar clusters therein.

  20. Nuclear Translocation Sequence and Region in Autographa californica Multiple Nucleopolyhedrovirus ME53 That Are Important for Optimal Baculovirus Production

    PubMed Central

    Liu, Yang; de Jong, Jondavid; Nagy, Éva; Theilmann, David A.

    2016-01-01

    ABSTRACT Autographa californica multiple nucleopolyhedrovirus (AcMNPV) is in the family Baculoviridae, genus Alphabaculovirus. AcMNPV me53 is a highly conserved immediate early gene in all lepidopteran baculoviruses that have been sequenced and is transcribed up to late times postinfection. Although me53 is not essential for viral DNA synthesis, infectious budded virus (BV) production is greatly attenuated when it is deleted. ME53 associates with the nucleocapsid on both budded virus and occlusion-derived virus, but not with the virus envelope. ME53 colocalizes in plasma membrane foci with the envelope glycoprotein GP64 in a GP64-dependent manner. ME53 localizes in the cytoplasm early postinfection, and despite the lack of a reported nuclear localization signal (NLS), ME53 translocates to the nucleus at late times postinfection. To map determinants of ME53 that facilitate its nuclear translocation, recombinant AcMNPV bacmids containing a series of ME53 truncations, internal deletions, and peptides fused with hemagglutinin (HA) or green fluorescent protein (GFP) tags were constructed. Intracellular-localization studies identified residues within amino acids 109 to 137 at the N terminus of ME53 that acted as the nuclear translocation sequence (NTS), facilitating its nuclear transport at late times postinfection. The first 100 N-terminal amino acids and the last 50 C-terminal amino acids of ME53 are dispensable for high levels of budded virus production. The region within amino acids 101 to 398, which also contains the NTS, is critical for optimal levels of budded virus production. IMPORTANCE Baculovirus me53 is a conserved immediate early gene found in all sequenced lepidopteran alpha- and betabaculoviruses. We first identified residues within amino acids 109 to 137 at the N terminus that act as the ME53 nuclear translocation sequence (NTS) to facilitate its nuclear translocation and defined an internal region within amino acids 101 to 398, which includes the NTS, as

  1. Dark matter concentrations in galactic nuclei according to polytropic models

    NASA Astrophysics Data System (ADS)

    Saxton, Curtis J.; Younsi, Ziri; Wu, Kinwah

    2016-10-01

    We calculate the radial profiles of galaxies where the nuclear region is self-gravitating, consisting of self-interacting dark matter (SIDM) with F degrees of freedom. For sufficiently high density this dark matter becomes collisional, regardless of its behaviour on galaxy scales. Our calculations show a spike in the central density profile, with properties determined by the dark matter microphysics, and the densities can reach the `mean density' of a black hole (from dividing the black hole mass by the volume enclosed by the Schwarzschild radius). For a galaxy halo of given compactness (χ ≡ 2GM/Rc2), certain values for the dark matter entropy yield a dense central object lacking an event horizon. For some soft equations of state of the SIDM (e.g. F ≳ 6), there are multiple horizonless solutions at given compactness. Although light propagates around and through a sphere composed of dark matter, it is gravitationally lensed and redshifted. While some calculations give non-singular solutions, others yield solutions with a central singularity. In all cases, the density transitions smoothly from the central body to the dark matter envelope around it, and to the galaxy's dark matter halo. We propose that pulsar timing observations will be able to distinguish between systems with a centrally dense dark matter sphere (for different equations of state) and conventional galactic nuclei that harbour a supermassive black hole.

  2. Active galactic nuclei as scaled-up Galactic black holes.

    PubMed

    McHardy, I M; Koerding, E; Knigge, C; Uttley, P; Fender, R P

    2006-12-01

    A long-standing question is whether active galactic nuclei (AGN) vary like Galactic black hole systems when appropriately scaled up by mass. If so, we can then determine how AGN should behave on cosmological timescales by studying the brighter and much faster varying Galactic systems. As X-ray emission is produced very close to the black holes, it provides one of the best diagnostics of their behaviour. A characteristic timescale--which potentially could tell us about the mass of the black hole--is found in the X-ray variations from both AGN and Galactic black holes, but whether it is physically meaningful to compare the two has been questioned. Here we report that, after correcting for variations in the accretion rate, the timescales can be physically linked, revealing that the accretion process is exactly the same for small and large black holes. Strong support for this linkage comes, perhaps surprisingly, from the permitted optical emission lines in AGN whose widths (in both broad-line AGN and narrow-emission-line Seyfert 1 galaxies) correlate strongly with the characteristic X-ray timescale, exactly as expected from the AGN black hole masses and accretion rates. So AGN really are just scaled-up Galactic black holes.

  3. Active galactic nuclei as scaled-up Galactic black holes.

    PubMed

    McHardy, I M; Koerding, E; Knigge, C; Uttley, P; Fender, R P

    2006-12-01

    A long-standing question is whether active galactic nuclei (AGN) vary like Galactic black hole systems when appropriately scaled up by mass. If so, we can then determine how AGN should behave on cosmological timescales by studying the brighter and much faster varying Galactic systems. As X-ray emission is produced very close to the black holes, it provides one of the best diagnostics of their behaviour. A characteristic timescale--which potentially could tell us about the mass of the black hole--is found in the X-ray variations from both AGN and Galactic black holes, but whether it is physically meaningful to compare the two has been questioned. Here we report that, after correcting for variations in the accretion rate, the timescales can be physically linked, revealing that the accretion process is exactly the same for small and large black holes. Strong support for this linkage comes, perhaps surprisingly, from the permitted optical emission lines in AGN whose widths (in both broad-line AGN and narrow-emission-line Seyfert 1 galaxies) correlate strongly with the characteristic X-ray timescale, exactly as expected from the AGN black hole masses and accretion rates. So AGN really are just scaled-up Galactic black holes. PMID:17151661

  4. Nuclear power-related facilities and neighboring land price: a case study on the Mutsu-Ogawara region, Japan.

    PubMed

    Yamane, Fumihiro; Ohgaki, Hideaki; Asano, Kota

    2011-12-01

    From the perspective of risk, nuclear-power-related facilities (NPRFs) are often regarded as locally undesirable land use. However, construction of NPRFs contributes to social infrastructural improvement and job creation in the host communities. This raises a question: How large are these positive and negative effects? To approach this question from an economic viewpoint, we estimated the hedonic land price function for the Mutsu-Ogawara region of Japan from 1976 to 2004 and analyzed year-by-year fluctuations in land prices around the NPRFs located there. Land prices increased gradually in the neighborhood of the nuclear fuel cycle facilities (NFCFs) in Rokkasho Village, except for some falling (i) from 1982 to 1983 (the first official announcement of the project of construction came in 1983), (ii) from 1987 to 1988 (in 1988, the construction began and opposition movements against the project reached their peak), and (iii) from 1998 to 1999 (the pilot carry-in of spent fuels into the reprocessing plant began in 1998). Land prices around the Higashidori Nuclear Power Plant decreased during the period 1981-1982, when the Tohoku Electric Power Corp. and Tokyo Electric Power Corp. announced their joint construction plan. On the other hand, we obtained some results, even though not significant, indicating that land prices around Ohminato and Sekinehama harbors changed with the arrival and departure of the nuclear ship Mutsu, which suffered a radiation leak in 1974. PMID:21488926

  5. Basic amino acid residues located in the N-terminal region of BEND3 are essential for its nuclear localization

    SciTech Connect

    Shiheido, Hirokazu Shimizu, Jun

    2015-02-20

    BEN domain-containing protein 3 (BEND3) has recently been reported to function as a heterochromatin-associated protein in transcriptional repression in the nucleus. BEND3 should have nuclear localization signals (NLSs) to localize to the nucleus in light of its molecular weight, which is higher than that allowed to pass through nuclear pore complexes. We here analyzed the subcellular localization of deletion/site-directed mutants of human BEND3 by an immunofluorescence assay in an attempt to identify the amino acids essential for its nuclear localization. We found that three basic amino acid residues located in the N-terminal region of BEND3 (BEND3{sub 56–58}, KRK) are essential, suggesting that these residues play a role as a functional NLS. These results provide valuable information for progressing research on BEND3. - Highlights: • BEND3 localizes to the nucleus. • The N-terminal 60 amino acids region of BEND3 contains NLS. • Amino acids located between 56 and 58 of BEND3 (KRK) are part of NLS. • KRK motif is highly conserved among BEND3 homologs.

  6. Investigation of the Chromosome Regions with Significant Affinity for the Nuclear Envelope in Fruit Fly – A Model Based Approach

    PubMed Central

    Kinney, Nicholas Allen; Sharakhov, Igor V.; Onufriev, Alexey V.

    2014-01-01

    Three dimensional nuclear architecture is important for genome function, but is still poorly understood. In particular, little is known about the role of the “boundary conditions” – points of attachment between chromosomes and the nuclear envelope. We describe a method for modeling the 3D organization of the interphase nucleus, and its application to analysis of chromosome-nuclear envelope (Chr-NE) attachments of polytene (giant) chromosomes in Drosophila melanogaster salivary glands. The model represents chromosomes as self-avoiding polymer chains confined within the nucleus; parameters of the model are taken directly from experiment, no fitting parameters are introduced. Methods are developed to objectively quantify chromosome territories and intertwining, which are discussed in the context of corresponding experimental observations. In particular, a mathematically rigorous definition of a territory based on convex hull is proposed. The self-avoiding polymer model is used to re-analyze previous experimental data; the analysis suggests 33 additional Chr-NE attachments in addition to the 15 already explored Chr-NE attachments. Most of these new Chr-NE attachments correspond to intercalary heterochromatin – gene poor, dark staining, late replicating regions of the genome; however, three correspond to euchromatin – gene rich, light staining, early replicating regions of the genome. The analysis also suggests 5 regions of anti-contact, characterized by aversion for the NE, only two of these correspond to euchromatin. This composition of chromatin suggests that heterochromatin may not be necessary or sufficient for the formation of a Chr-NE attachment. To the extent that the proposed model represents reality, the confinement of the polytene chromosomes in a spherical nucleus alone does not favor the positioning of specific chromosome regions at the NE as seen in experiment; consequently, the 15 experimentally known Chr-NE attachment positions do not appear to

  7. Galactic Halos of Hydrogen

    NASA Technical Reports Server (NTRS)

    2005-01-01

    This image shows two companion galaxies, NGC 4625 (top) and NGC 4618 (bottom), and their surrounding cocoons of cool hydrogen gas (purple). The huge set of spiral arms on NGC 4625 (blue) was discovered by the ultraviolet eyes of NASA's Galaxy Evolution Explorer. Though these arms are nearly invisible when viewed in optical light, they glow brightly in ultraviolet. This is because they are bustling with hot, newborn stars that radiate primarily ultraviolet light.

    The vibrant spiral arms are also quite lengthy, stretching out to a distance four times the size of the galaxy's core. They are part of the largest ultraviolet galactic disk discovered so far.

    Astronomers do not know why NGC 4625 grew arms while NGC 4618 did not. The purple nebulosity shown here illustrates that hydrogen gas - an ingredient of star formation - is diffusely distributed around both galaxies. This means that other unknown factors led to the development of the arms of NGC 4625.

    Located 31 million light-years away in the constellation Canes Venatici, NGC 4625 is the closest galaxy ever seen with such a young halo of arms. It is slightly smaller than our Milky Way, both in size and mass. However, the fact that this galaxy's disk is forming stars very actively suggests that it might evolve into a more massive and mature galaxy resembling our own.

    The image is composed of ultraviolet, visible-light and radio data, from the Galaxy Evolution Explorer, the California Institute of Technology's Digitized Sky Survey, and the Westerbork Synthesis Radio Telescope, the Netherlands, respectively. Near-ultraviolet light is colored green; far-ultraviolet light is colored blue; and optical light is colored red. Radio emissions are colored purple.

  8. JASMINE: galactic structure surveyor

    NASA Astrophysics Data System (ADS)

    Gouda, Naoteru; Kobayashi, Yukiyasu; Yamada, Yoshiyuki; Yano, Taihei; Tsujimoto, Takuji; Suganuma, Masahiro; Niwa, Yoshito; Yamauchi, Masahiro; Kawakatsu, Yasuhiro; Matsuhara, Hideo; Noda, Atsushi; Tsuiki, Atsuo; Utashima, Masayoshi; Ogawa, Akira

    2006-06-01

    We introduce a Japanese plan of infrared(z-band:0.9μm) space astrometry(JASMINE-project). JASMINE is the satellite (Japan Astrometry Satellite Mission for INfrared Exploration) which will measure distances and apparent motions of stars around the center of the Milky Way with yet unprecedented precision. It will measure parallaxes, positions with the accuracy of 10 micro-arcsec and proper motions with the accuracy of ~ 4microarcsec/ year for stars brighter than z=14mag. JASMINE can observe about ten million stars belonging to the bulge components of our Galaxy, which are hidden by the interstellar dust extinction in optical bands. Number of stars with σ/π < 0.1 in the direction of the Galactic central bulge is about 1000 times larger than those observed in optical bands, where π is a parallax and σ is an error of the parallax. With the completely new "map of the bulge in the Milky Way", it is expected that many new exciting scientific results will be obtained in various fields of astronomy. Presently, JASMINE is in a development phase, with a target launch date around 2015. We adopt the following instrument design of JASMINE in order to get the accurate positions of many stars. A 3-mirrors optical system(modified Korsch system)with a primary mirror of~ 0.85m is one of the candidate for the optical system. On the astro-focal plane, we put dozens of new type of CCDs for z-band to get a wide field of view. The accurate measurements of the astrometric parameters requires the instrument line-of-sight highly stability and the opto-mechanical highly stability of the payload in the JASMINE spacecraft. The consideration of overall system(bus) design is now going on in cooperation with Japan Aerospace Exploration Agency(JAXA).

  9. Galactic Habitable Orbits

    NASA Astrophysics Data System (ADS)

    Rahimi, A.; Mao, S.; Kawata, D.

    2014-03-01

    The fossil record shows that the Earth has experienced several mass extinctions over the past 500 million years1, and it has been suggested that there is a periodicity in extinction events on timescales of tens1 and/or hundreds of millions of years. Various hypotheses have been proposed to explain the cause of the mass extinctions, including the suggestion that the Earth's ozone layer may have been destroyed by intense radiation from a nearby supernovae2- 3, exposing the Earth's surface to damaging UV radiation. Recent observations of cores taken from the ocean floor revealed atoms of a very rare isotope of iron (60Fe) believed to have arrived on Earth around 2 million years ago as fallout from a nearby supernovae4. Astronomical evidence for that past supernovae was recently found in the debris of a young cluster of massive stars5, by tracing its past orbit, putting it at the right place at the right time to explain the mild extinction event. Here we report new high-resolution (both in space and time) N-body chemodynamical simulations (carried out with our novel code GCD+6) of the evolution of a model Milky Way Galaxy, tracing the orbit of èsun-like' stars over a 500 million year period, checking the proximity to supernovae throughout the history of the orbit and comparing the times when this occurs with past mass extinctions on Earth. We additionally explain the important effects of the spiral arm pattern, radial migration of stars and Galactic chemistry on habitability.

  10. A Disturbed Galactic Duo

    NASA Astrophysics Data System (ADS)

    2011-04-01

    The galaxies in this cosmic pairing, captured by the Wide Field Imager on the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile, display some curious features, demonstrating that each member of the duo is close enough to feel the distorting gravitational influence of the other. The gravitational tug of war has warped the spiral shape of one galaxy, NGC 3169, and fragmented the dust lanes in its companion NGC 3166. Meanwhile, a third, smaller galaxy to the lower right, NGC 3165, has a front-row seat to the gravitational twisting and pulling of its bigger neighbours. This galactic grouping, found about 70 million light-years away in the constellation Sextans (The Sextant), was discovered by the English astronomer William Herschel in 1783. Modern astronomers have gauged the distance between NGC 3169 (left) and NGC 3166 (right) as a mere 50 000 light-years, a separation that is only about half the diameter of the Milky Way galaxy. In such tight quarters, gravity can start to play havoc with galactic structure. Spiral galaxies like NGC 3169 and NGC 3166 tend to have orderly swirls of stars and dust pinwheeling about their glowing centres. Close encounters with other massive objects can jumble this classic configuration, often serving as a disfiguring prelude to the merging of galaxies into one larger galaxy. So far, the interactions of NGC 3169 and NGC 3166 have just lent a bit of character. NGC 3169's arms, shining bright with big, young, blue stars, have been teased apart, and lots of luminous gas has been drawn out from its disc. In NGC 3166's case, the dust lanes that also usually outline spiral arms are in disarray. Unlike its bluer counterpart, NGC 3166 is not forming many new stars. NGC 3169 has another distinction: the faint yellow dot beaming through a veil of dark dust just to the left of and close to the galaxy's centre [1]. This flash is the leftover of a supernova detected in 2003 and known accordingly as SN 2003cg. A supernova of this

  11. A Disturbed Galactic Duo

    NASA Astrophysics Data System (ADS)

    2011-04-01

    The galaxies in this cosmic pairing, captured by the Wide Field Imager on the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile, display some curious features, demonstrating that each member of the duo is close enough to feel the distorting gravitational influence of the other. The gravitational tug of war has warped the spiral shape of one galaxy, NGC 3169, and fragmented the dust lanes in its companion NGC 3166. Meanwhile, a third, smaller galaxy to the lower right, NGC 3165, has a front-row seat to the gravitational twisting and pulling of its bigger neighbours. This galactic grouping, found about 70 million light-years away in the constellation Sextans (The Sextant), was discovered by the English astronomer William Herschel in 1783. Modern astronomers have gauged the distance between NGC 3169 (left) and NGC 3166 (right) as a mere 50 000 light-years, a separation that is only about half the diameter of the Milky Way galaxy. In such tight quarters, gravity can start to play havoc with galactic structure. Spiral galaxies like NGC 3169 and NGC 3166 tend to have orderly swirls of stars and dust pinwheeling about their glowing centres. Close encounters with other massive objects can jumble this classic configuration, often serving as a disfiguring prelude to the merging of galaxies into one larger galaxy. So far, the interactions of NGC 3169 and NGC 3166 have just lent a bit of character. NGC 3169's arms, shining bright with big, young, blue stars, have been teased apart, and lots of luminous gas has been drawn out from its disc. In NGC 3166's case, the dust lanes that also usually outline spiral arms are in disarray. Unlike its bluer counterpart, NGC 3166 is not forming many new stars. NGC 3169 has another distinction: the faint yellow dot beaming through a veil of dark dust just to the left of and close to the galaxy's centre [1]. This flash is the leftover of a supernova detected in 2003 and known accordingly as SN 2003cg. A supernova of this

  12. Diffuse Galactic light at high Galactic latitude: nature and interpretation

    NASA Astrophysics Data System (ADS)

    Zagury, Frédéric

    2006-08-01

    The hypothesis of an extended red emission (ERE) in diffuse Galactic light (DGL) has been put forward in 1998 by Gordon, Witt & Friedmann who found that scattered starlight was not enough to explain the amount of DGL in the R band, in some high Galactic latitude directions. This paper re-investigates, for high Galactic latitudes, the brightnesses and colours of DGL, integrated star and galaxy light (ISGL), and of the total extrasolar light (ISGL+DGL) measured by Pioneer. Under the traditional assumption that DGL is forward scattering of background starlight by interstellar dust on the line of sight, ISGL and Pioneer have very close colours, as it is found by Gordon, Witt & Friedmann. Pioneer observations at high |b| thus accept an alternative and simple interpretation, with no involvement of ERE in DGL.

  13. VizieR Online Data Catalog: OGLE microlensing events in Galactic Bulge (Udalski+, 2000)

    NASA Astrophysics Data System (ADS)

    Udalski, A.; Zebrun, K.; Szymanski, M.; Kubiak, M.; Pietrzynski, G.; Soszynski, I.; Wozniak, P.

    2006-09-01

    We present the Catalog of microlensing events detected toward the Galactic bulge in three observing seasons, 1997-1999, during the OGLE-II microlensing survey. The search for microlensing events was performed using a database of about 4x109 photometric measurements of about 20.5 million stars from the Galactic bulge. The Catalog comprises 214 microlensing events found in the fields covering about 11 square degrees on the sky and distributed in different parts of the Galactic bulge. The sample includes 20 binary microlensing events, 14 of them are caustic crossing. In one case a double star is likely lensed. We present distribution of the basic parameters of microlensing events and show preliminary rate of microlensing in different regions of the Galactic bulge. The latter reveals clear dependence on the Galactic coordinates. The dependence on l indicates that the majority of lenses toward the Galactic bulge are located in the Galactic bar. Models of the Galactic bar seem to reasonably predict the observed spatial distribution of microlensing events in the Galactic bulge. All data presented in the Catalog and photometry of all events are available from the OGLE Internet archive. (3 data files).

  14. Study of galactic rotation curves in wormhole spacetime

    NASA Astrophysics Data System (ADS)

    Rahaman, Farook; Sen, Banashree; Chakraborty, Koushik; Shit, G. C.

    2016-03-01

    The spacetime of the galactic halo region is described by a wormhole like line element. We assume violation of Null Energy Condition (NEC) in the galactic halo. The Einstein Field equations are solved for two different conditions of pressure and density to obtain physical parameters like tangential velocity of test particles and parameters related to the wormhole geometry. The theoretical rotation curve of the test particles is plotted and compared the same with an observed rotation curve. We obtain a satisfactory fit between the observed curve and the curve obtained from the present theory for the radial distances in the range 9 Kpc to 100 Kpc.

  15. The Galactic center pulsar SGR J1745-29

    NASA Astrophysics Data System (ADS)

    Bower, Geoffrey C.

    2014-05-01

    The discovery of the Galactic center pulsar SGR J1745-29 has provided an important new window into plasma processes in the Galactic center (GC) interstellar medium, the population of compact objects in the GC, and the prospects for probing general relativistic effects through timing of a Sgr A* pulsar companion. We discuss here radio observations of the pulsar and how they are providing fresh insights. In particular, our results show that recent pulsar surveys had the sensitivity to detect many pulsars in the GC region without significant losses due to interstellar scattering. This raise the question of why only this pulsar close to Sgr A* has been detected.

  16. Photometric Surveys of the Galactic Bulge and Long Bar

    NASA Astrophysics Data System (ADS)

    Gerhard, O.; Wegg, C.; Portail, M.

    The Galactic bar and box/peanut bulge can be studied in an unrivaled manner, star-by-star, with detailed chemical information and full 3D kinematics. Because of intervening dust this is greatly facilitated by the availability of wide field deep NIR photometric surveys. Here we summarize recent results on the three-dimensional structure of the bulge and the long bar region, based on 2MASS, UKIDSS, and particularly the ongoing VVV survey. We also summarize results from dynamical models for the Galactic bulge constructed with the Made-to-Measure method.

  17. Understanding the kinematics of Galactic centre gas

    NASA Astrophysics Data System (ADS)

    Binney, James; Gerhard, Ortwin E.; Stark, Antony A.; Bally, John; Uchida, Keven I.

    1991-09-01

    A coherent picture is constructed of the Galaxy's H I, CO and CS emissions in the region l below 10 deg, b below 0.5 deg. The flow of gas at the Galactic center is dominated by a bar that has corotation at r = 2.4 + or - 0.5 kpc, which is viewed at an angle of 16 + or - 2 deg from its major axis. The first CO emission arises where gas is obliged to switch from x(1) orbits to x(2) orbits, in the notation of Contopoulos. This gives rise to a shock and a clear signature in the (l, v) diagram. The great Galactic center molecular clouds such as Sgr B, are on x(2) orbits. From the structure of the H I terminal velocity envelope, it is deduced that the central mass density scales as rho varies with r to the -1.75 power out to at least about 1.2 kpc along the bar's major axis. Consequently, the circular velocity curve is rising significantly through the radius range where naive analysis of the tangent velocity leads to a falling rotation curve. The great ring of molecular material at r of about 3.5 kpc is probably associated with the bar's outer Lindblad resonance, and the region of low gas densities inward from there with corotation.

  18. The GLFG repetitive region of the nucleoporin Nup116p interacts with Kap95p, an essential yeast nuclear import factor

    PubMed Central

    1995-01-01

    Nup116p is a member of a family of five yeast nuclear pore complex (NPC) proteins that share an amino terminal region of repetitive tetrapeptide "GLFG" motifs. Previous experiments characterized the unique morphological perturbations that occur in a nup116 null mutant: temperature-sensitive formation of nuclear envelope seals over the cytoplasmic face of the NPC (Wente, S. R., and G. Blobel. 1993. J. Cell Biol. 123:275-284). Three approaches have been taken to dissect the structural basis for Nup116p's role in NPC function. First, deletion mutagenesis analysis of NUP116 revealed that the GLFG region was required for NPC function. This was not true for the other four yeast GLFG family members (Nup49p, Nup57p, Nup100p, and Nup145p). Moreover, deletion of either half of Nup116p's GLFG repeats or replacement of Nup116p's GLFG region with either Nup100p's GLFG region or Nsp1p's FXFG repetitive region abolishes the function of Nup116p. At a semipermissive growth temperature, the cells lacking Nup116p's GLFG region displayed a diminished capacity for nuclear import. Second, overexpression of Nup116p's GLFG region severely inhibited cell growth, rapidly blocked polyadenylated-RNA export, and fragmented the nucleolus. Although it inhibited nuclear export, the overexpressed GLFG region appeared predominantly localized in the cytoplasm and NPC/nuclear envelope structure was not perturbed in thin section electron micrographs. Finally, using biochemical and two-hybrid analysis, an interaction was characterized between Nup116p's GLFG region and Kap95p, an essential yeast homologue of the vertebrate nuclear import factor p97/Imp90/karopherin beta. These data show that Nup116p's GLFG region has an essential role in mediating nuclear transport. PMID:8557738

  19. Nuclear ribosomal internal transcribed spacer (ITS) region as a universal DNA barcode marker for Fungi

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Six DNA regions were evaluated in a multi-national, multi-laboratory consortium as potential DNA barcodes for Fungi, the second largest kingdom of eukaryotic life. The region of the mitochondrial cytochrome c oxidase subunit 1 used as the animal barcode was excluded as a potential marker, because it...

  20. [The role of chromosomal regions anchored to the nuclear envelope in the functional organization of chromosomes].

    PubMed

    Shabarina, A N; Shostak, N G; Glazkov, M V

    2010-09-01

    The functional characteristics of the DNA fragments responsible for chromosome attachment to the nuclear envelope during the interphase (neDNAs) have been studied. The neDNAs flanking the transgene have been found to promote a steadily high rate of its expression, irrespective of the site of its insertion into the host chromosomes. At the same time, neDNAs themselves have no transcription regulatory functions. PMID:21061611

  1. Yield ratio estimates using regional Pn and Pg from North Korea's underground nuclear explosions

    NASA Astrophysics Data System (ADS)

    Kim, Tae Sung; Kang, Ik-Bum; Kim, Geun-Young

    2009-11-01

    On May 25, 2009 North Korea executed a second nuclear test in the vicinity of P'unggyeri where the first nuclear test was performed on October 9, 2006. Seismic signals from the two underground nuclear explosions (UNEs) are recorded at broadband stations in South Korea and China. Seismic signals from fourteen broadband stations operated by the Korea Institute of Geoscience and Mineral Resources (KIGAM), three broadband stations of Korea Meteorological Administration (KMA) in South Korea and the Mudanjiang station (MDJ) of GSN in China are used for this study. Clear Pn, Pg, and Lg phases propagated over 800 km. The nearly co-located two UNEs and seismic recordings at the same stations enable us to estimate the ratio of the Pn and Pg displacement amplitude spectra between two events by eliminating the path effect. The 95% confidence interval of the mean yield ratio is constrained as a function of the depth ratio and all the estimates of Pn and Pg spectral ratios. The mean yield ratio ranges from 3.45 to 6.36 in the 95% confidence interval based on the depth range estimates by Bennett (2008, 2009).

  2. The Herschel view of the Galactic center

    NASA Astrophysics Data System (ADS)

    Bally, John; Hi-GAL Team

    2014-05-01

    The 3.5 meter diameter Herschel Space Observatory conducted a ˜720 square-degree survey of the Galactic plane, the Herschel Galactic plane survey (Hi-GAL). These data provide the most sensitive and highest resolution observations of the far-IR to sub-mm continuum from the central molecular zone (CMZ) at λ = 70, 160, 250, 350, and 500 μm obtained to date. Hi-GAL can be used to map the distributions of temperature and column density of dust in CMZ clouds, warm dust in Hii regions, and identify highly embedded massive protostars and clusters and the dusty shells ejected by supergiant stars. These data enable classification of sources and re-evaluation of the current and recent star-formation rate in the CMZ. The outer CMZ beyond |l| = 0.9 degrees (Rgal > 130 pc) contains most of the dense (n > 104 cm-3 gas in the Galaxy but supports very little star formation. The Hi-GAL and Spitzer data show that almost all star formation occurs in clouds moving on x 2 orbits at Rgal < 100 pc. While the 106 M⊙ Sgr B2 complex, the 50 km s-1 cloud near Sgr A, and the Sgr C region are forming clusters of massive stars, other clouds are relatively inactive star formers, despite their high densities, large masses, and compact sizes. The asymmetric distribution of dense gas about Sgr A* on degree scales (most dense CMZ gas and dust is at positive Galactic longitudes and positive VLSR ) and compact 24 μm sources (most are at negative longitudes) may indicate that eposidic mini-starbursts occasionally `blow-out' a portion of the gas on these x 2 orbits. The resulting massive-star feedback may fuel the compact 30 pc scale Galactic center bubble associated with the Arches and Quintuplet clusters, the several hundred pc scale Sofue-Handa lobe, and the kpc-scale Fermi/LAT bubble, making it the largest `superbubble' in the Galaxy. A consequence of this model is that in our Galaxy, instead of the supermassive black hole (SMBH) limiting star formation, star formation may limit the growth of

  3. Character and properties of near-infrared excess sources in the Galactic centre

    NASA Astrophysics Data System (ADS)

    Zajacek, Michal; Eckart, Andreas; Valencia-S., Monika; Peissker, Florian; Karas, Vladimir

    2016-06-01

    Near-infrared observations reveal a large number of young stars in the innermost parsec of the Galactic centre, with estimated ages of a few million years. Recently, a group of near-infrared excess sources located in the S-cluster has been studied and the basic characteristics of their continuum and spectra have been determined. One of the objects, Dusty S-cluster object (DSO/G2), has recently passed the pericentre at approx. 2000 Schwarzschild radii and remained compact, which implies that at least in this case it is a dust-enshrouded star, plausibly even younger than numerous massive OB stars in the region. The occurrence of such a young object supports the theory of continuing star-formation in the Galactic centre.We will report on our analysis of how these objects - plausibly pre-main-sequence stars - that are apparently still embedded in dusty envelopes could have formed in the innermost parts of the dense nuclear star cluster. In particular, we study under which conditions infalling molecular gas can reach sufficient densities to collapse, fragment and form stars. Furthermore, we analyze the typical timescales that determine the stability of circumstellar envelopes and disks that give rise to the near-infrared excess of these young objects. The stability and optical depth of the envelopes determine the spectral energy distribution, for which we give predictions. In the analysis, we employ dynamical modelling (analytical and numerical) and 3D Monte Carlo radiative transfer modelling.

  4. Deep Mid-Infrared Silicate Absorption as a Diagnostic of Obscuring Geometry toward Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Levenson, N. A.; Sirocky, M. M.; Hao, L.; Spoon, H. W. W.; Marshall, J. A.; Elitzur, M.; Houck, J. R.

    2007-01-01

    The silicate cross section peak near 10 μm produces emission and absorption features in the spectra of dusty galactic nuclei observed with the Spitzer Space Telescope. Especially in ultraluminous infrared galaxies, the observed absorption feature can be extremely deep, as IRAS 08572+3915 illustrates. A foreground screen of obscuration cannot reproduce this observed feature, even at a large optical depth. Instead, the deep absorption requires a nuclear source to be deeply embedded in a smooth distribution of material that is both geometrically and optically thick. In contrast, a clumpy medium can produce only shallow absorption or emission, which are characteristic of optically identified active galactic nuclei. In general, the geometry of the dusty region and the total optical depth, rather than the grain composition or heating spectrum, determine the silicate feature's observable properties. The apparent optical depth calculated from the ratio of line to continuum emission generally fails to accurately measure the true optical depth. The obscuring geometry, not the nature of the embedded source, also determines the far-IR spectral shape.

  5. Is There a Maximum Mass for Black Holes in Galactic Nuclei?

    NASA Astrophysics Data System (ADS)

    Inayoshi, Kohei; Haiman, Zoltán

    2016-09-01

    The largest observed supermassive black holes (SMBHs) have a mass of {M}{{BH}}≃ {10}10 {\\text{}}{M}⊙ , nearly independent of redshift, from the local (z≃ 0) to the early (z\\gt 6) universe. We suggest that the growth of SMBHs above a few × {10}10 {\\text{}}{M}⊙ is prevented by small-scale accretion physics, independent of the properties of their host galaxies or of cosmology. Growing more massive BHs requires a gas supply rate from galactic scales onto a nuclear region as high as ≳ {10}3 {M}⊙ {{{yr}}}-1. At such a high accretion rate, most of the gas converts to stars at large radii (˜10-100 pc), well before reaching the BH. We adopt a simple model for a star-forming accretion disk and find that the accretion rate in the subparsec nuclear region is reduced to the smaller value of at most a few × {M}⊙ {{{yr}}}-1. This prevents SMBHs from growing above ≃ {10}11 {\\text{}}{M}⊙ in the age of the universe. Furthermore, once an SMBH reaches a sufficiently high mass, this rate falls below the critical value at which the accretion flow becomes advection dominated. Once this transition occurs, BH feeding can be suppressed by strong outflows and jets from hot gas near the BH. We find that the maximum SMBH mass, given by this transition, is between {M}{{BH,max}}≃ (1{--}6)× {10}10 {\\text{}}{M}⊙ , depending primarily on the efficiency of angular momentum transfer inside the galactic disk, and not on other properties of the host galaxy.

  6. Observing the next galactic supernova

    SciTech Connect

    Adams, Scott M.; Kochanek, C. S.; Beacom, John F.; Stanek, K. Z.; Vagins, Mark R.

    2013-12-01

    No supernova (SN) in the Milky Way has been observed since the invention of the optical telescope, instruments for other wavelengths, neutrino detectors, or gravitational wave observatories. It would be a tragedy to miss the opportunity to fully characterize the next one. To aid preparations for its observations, we model the distance, extinction, and magnitude probability distributions of a successful Galactic core-collapse supernova (ccSN), its shock breakout radiation, and its massive star progenitor. We find, at very high probability (≅ 100%), that the next Galactic SN will easily be detectable in the near-IR and that near-IR photometry of the progenitor star very likely (≅ 92%) already exists in the Two Micron All Sky Survey. Most ccSNe (98%) will be easily observed in the optical, but a significant fraction (43%) will lack observations of the progenitor due to a combination of survey sensitivity and confusion. If neutrino detection experiments can quickly disseminate a likely position (∼3°), we show that a modestly priced IR camera system can probably detect the shock breakout radiation pulse even in daytime (64% for the cheapest design). Neutrino experiments should seriously consider adding such systems, both for their scientific return and as an added and internal layer of protection against false triggers. We find that shock breakouts from failed ccSNe of red supergiants may be more observable than those of successful SNe due to their lower radiation temperatures. We review the process by which neutrinos from a Galactic ccSN would be detected and announced. We provide new information on the EGADS system and its potential for providing instant neutrino alerts. We also discuss the distance, extinction, and magnitude probability distributions for the next Galactic Type Ia supernova (SN Ia). Based on our modeled observability, we find a Galactic ccSN rate of 3.2{sub −2.6}{sup +7.3} per century and a Galactic SN Ia rate of 1.4{sub −0.8}{sup +1.4} per

  7. Gas clouds in galactic bulges

    SciTech Connect

    Mathews, W.G.; Murray, S.D.

    1987-01-01

    An analytical model is defined for the orbits of gas clouds moving through a low-density, hot resisting medium in a spiral galactic bulge. The model includes a virial equation that accounts for internal and magnetic energy, external self-pressure, self-gravity and tidal and differential shear stresses, and a criterion for assessing the Rayleigh-Taylor stability of clouds moving within a confining medium. Results are discussed from use of the model to predict the orbital decay efficiency of clouds at different radii moving in a galactic bulge similar to that of the Galaxy. 52 references.

  8. Galactic Center gamma-ray ``excess'' from an active past of the Galactic Centre?

    NASA Astrophysics Data System (ADS)

    Petrović, Jovana; Dario Serpico, Pasquale; Zaharijaš, Gabrijela

    2014-10-01

    Several groups have recently claimed evidence for an unaccounted gamma-ray excess over the diffuse backgrounds at few GeV in the Fermi-LAT data in a region around the Galactic Center, consistent with a dark matter annihilation origin. We demonstrate that the main spectral and angular features of this excess can be reproduced if they are mostly due to inverse Compton emission from high-energy electrons injected in a burst event of ~ 1052÷1053 erg roughly Script O(106) years ago. We consider this example as a proof of principle that time-dependent phenomena need to be understood and accounted for—together with detailed diffuse foregrounds and unaccounted ``steady state'' astrophysical sources—before any robust inference can be made about dark matter signals at the Galactic Center. In addition, we point out that the timescale suggested by our study, which controls both the energy cutoff and the angular extension of the signal, intriguingly matches (together with the energy budget) what is indirectly inferred by other evidences suggesting a very active Galactic Center in the past, for instance related to intense star formation and accretion phenomena.

  9. Galactic Center gamma-ray ''excess'' from an active past of the Galactic Centre?

    SciTech Connect

    Petrović, Jovana; Serpico, Pasquale Dario; Zaharijaš, Gabrijela E-mail: serpico@lapth.cnrs.fr

    2014-10-01

    Several groups have recently claimed evidence for an unaccounted gamma-ray excess over the diffuse backgrounds at few GeV in the Fermi-LAT data in a region around the Galactic Center, consistent with a dark matter annihilation origin. We demonstrate that the main spectral and angular features of this excess can be reproduced if they are mostly due to inverse Compton emission from high-energy electrons injected in a burst event of ∼ 10{sup 52}÷10{sup 53} erg roughly O(10{sup 6}) years ago. We consider this example as a proof of principle that time-dependent phenomena need to be understood and accounted for—together with detailed diffuse foregrounds and unaccounted ''steady state'' astrophysical sources—before any robust inference can be made about dark matter signals at the Galactic Center. In addition, we point out that the timescale suggested by our study, which controls both the energy cutoff and the angular extension of the signal, intriguingly matches (together with the energy budget) what is indirectly inferred by other evidences suggesting a very active Galactic Center in the past, for instance related to intense star formation and accretion phenomena.

  10. The Heliosphere and Galactic Cosmic Rays

    NASA Video Gallery

    The heliosphere deflects galactic cosmic rays from entering the system. Galactic cosmic rays are a very high energy form of particle radiation that are extremely difficult to shield against and are...

  11. THE STELLAR KINEMATIC CENTER AND THE TRUE GALACTIC NUCLEUS OF NGC 253

    SciTech Connect

    Mueller-Sanchez, F.; Fernandez-Ontiveros, J. A.; Acosta-Pulido, J. A.; Prieto, M. A.

    2010-06-20

    We present the first sub-arcsecond resolution two-dimensional stellar kinematics and X-ray observations of the prototypical starburst galaxy NGC 253 which define the position and nature of the galactic nucleus. These observations comprise some of the best probes of the central 300 pc of NGC 253, the nearest massive galaxy undergoing a powerful starburst, and will allow us to gain more insight into the nature of the centers of starburst galaxies. We get an estimate of the stellar kinematic center location corresponding to an area of r {approx} 1.''2 centered {approx}0.''7 southwest (SW) from the radio core, and historically presumed nucleus, TH2. Newly processed Chandra data reveal a central point-like hard X-ray source (X-1) lying {approx}0.''4 SW from the kinematic center. Very accurate alignment between radio, infrared, and X-ray sources in the nuclear region shows that TH2, the IR photometric center, and X-1 are not associated with each other. As the kinematic center is consistent with the positions of TH2 and X-1, and both could be a manifestation of nuclear activity, we consider the two as possible galactic nucleus candidates. Although TH2 is the strongest compact radio source in the nuclear region, it does not have any infrared, optical, or X-ray counterparts. If the kinematic center is associated with this source, by analogy we suggest that the nucleus of NGC 253 resembles our Galactic center Sgr A*. On the other hand, X-1 is a heavily absorbed object (N{sub H} = 7.5 x 10{sup 23} cm{sup -2}) only detected at energies >2 keV (L{sub 2-10{sub keV}} {approx} 10{sup 40} erg s{sup -1}). If X-1 is instead associated with the kinematic center, the nucleus of NGC 253 is compatible with an obscured low-luminosity active galactic nucleus (AGN) or a spatially resolved super star cluster (SSC) brightening up in X-rays most probably due to young supernovae or supernova remnants, a situation also observed in the nuclear starburst of M82. If no SSC is associated with the

  12. Radiotherapy and Nuclear Medicine Project for an Integral Oncology Center at the Oaxaca High Specialization Regional Hospital

    SciTech Connect

    De Jesus, M.; Trujillo-Zamudio, F. E.

    2010-12-07

    A building project of Radiotherapy and Nuclear Medicine services (diagnostic and therapy), within an Integral Oncology Center (IOC), requires interdisciplinary participation of architects, biomedical engineers, radiation oncologists and medical physicists. This report focus on the medical physicist role in designing, building and commissioning stages, for the final clinical use of an IOC at the Oaxaca High Specialization Regional Hospital (HRAEO). As a first step, during design stage, the medical physicist participates in discussions about radiation safety and regulatory requirements for the National Regulatory Agency (called CNSNS in Mexico). Medical physicists propose solutions to clinical needs and take decisions about installing medical equipment, in order to fulfill technical and medical requirements. As a second step, during the construction stage, medical physicists keep an eye on building materials and structural specifications. Meanwhile, regulatory documentation must be sent to CNSNS. This documentation compiles information about medical equipment, radioactivity facility, radiation workers and nuclear material data, in order to obtain the license for the linear accelerator, brachytherapy and nuclear medicine facilities. As a final step, after equipment installation, the commissioning stage takes place. As the conclusion, we show that medical physicists are essentials in order to fulfill with Mexican regulatory requirements in medical facilities.

  13. The N-terminal region of eukaryotic translation initiation factor 5A signals to nuclear localization of the protein

    SciTech Connect

    Parreiras-e-Silva, Lucas T.; Gomes, Marcelo D.; Oliveira, Eduardo B.; Costa-Neto, Claudio M.

    2007-10-19

    The eukaryotic translation initiation factor 5A (eIF5A) is a ubiquitous protein of eukaryotic and archaeal organisms which undergoes hypusination, a unique post-translational modification. We have generated a polyclonal antibody against murine eIF5A, which in immunocytochemical assays in B16-F10 cells revealed that the endogenous protein is preferentially localized to the nuclear region. We therefore analyzed possible structural features present in eIF5A proteins that could be responsible for that characteristic. Multiple sequence alignment analysis of eIF5A proteins from different eukaryotic and archaeal organisms showed that the former sequences have an extended N-terminal segment. We have then performed in silico prediction analyses and constructed different truncated forms of murine eIF5A to verify any possible role that the N-terminal extension might have in determining the subcellular localization of the eIF5A in eukaryotic organisms. Our results indicate that the N-terminal extension of the eukaryotic eIF5A contributes in signaling this protein to nuclear localization, despite of bearing no structural similarity with classical nuclear localization signals.

  14. Radiotherapy and Nuclear Medicine Project for an Integral Oncology Center at the Oaxaca High Specialization Regional Hospital

    NASA Astrophysics Data System (ADS)

    De Jesús, M.; Trujillo-Zamudio, F. E.

    2010-12-01

    A building project of Radiotherapy & Nuclear Medicine services (diagnostic and therapy), within an Integral Oncology Center (IOC), requires interdisciplinary participation of architects, biomedical engineers, radiation oncologists and medical physicists. This report focus on the medical physicist role in designing, building and commissioning stages, for the final clinical use of an IOC at the Oaxaca High Specialization Regional Hospital (HRAEO). As a first step, during design stage, the medical physicist participates in discussions about radiation safety and regulatory requirements for the National Regulatory Agency (called CNSNS in Mexico). Medical physicists propose solutions to clinical needs and take decisions about installing medical equipment, in order to fulfill technical and medical requirements. As a second step, during the construction stage, medical physicists keep an eye on building materials and structural specifications. Meanwhile, regulatory documentation must be sent to CNSNS. This documentation compiles information about medical equipment, radioactivity facility, radiation workers and nuclear material data, in order to obtain the license for the linear accelerator, brachytherapy and nuclear medicine facilities. As a final step, after equipment installation, the commissioning stage takes place. As the conclusion, we show that medical physicists are essentials in order to fulfill with Mexican regulatory requirements in medical facilities.

  15. METHANOL MASER EMISSION FROM GALACTIC CENTER SOURCES WITH EXCESS 4.5 {mu}m EMISSION

    SciTech Connect

    Chambers, E. T.; Yusef-Zadeh, F.; Roberts, D. E-mail: zadeh@northwestern.edu

    2011-05-20

    We present a study of signatures of on-going star formation in a sample of protostellar objects with enhanced 4.5 {mu}m emission ('green' sources) near the Galactic center. To understand how star formation in the Galactic center region compares to that of the Galactic disk, we used the Expanded Very Large Array to observe radiatively excited Class II 6.7 GHz CH{sub 3}OH masers and collisionally excited Class I 44 GHz CH{sub 3}OH masers, both tracers of high-mass star formation, toward a sample of 34 Galactic center and foreground 'green' sources. We find that 33% {+-} 15% of Galactic center sources are coincident with 6.7 GHz masers, and that 44% {+-} 17% of foreground sources are coincident with 6.7 GHz masers. For 44 GHz masers, we find correlation rates of 27% {+-} 13% and 25% {+-} 13% for Galactic center green sources and foreground green sources, respectively. Based on these CH{sub 3}OH maser detection rates, as well as correlations of green sources with other tracers of star formation, such as 24 {mu}m emission and infrared dark clouds (IRDCs), we find no significant difference between the green sources in the Galactic center and those foreground to it. This suggests that once the star formation process has begun, the environmental differences between the Galactic center region and the Galactic disk have little effect on its observational signatures. We do find, however, some evidence that may support a recent episode of star formation in the Galactic center region.

  16. Radiation heat transfer calculations for the uranium fuel-containment region of the nuclear light bulb engine.

    NASA Technical Reports Server (NTRS)

    Rodgers, R. J.; Latham, T. S.; Krascella, N. L.

    1971-01-01

    Calculation results are reviewed of the radiant heat transfer characteristics in the fuel and buffer gas regions of a nuclear light bulb engine based on the transfer of energy by thermal radiation from gaseous uranium fuel in a neon vortex, through an internally cooled transparent wall, to seeded hydrogen propellant. The results indicate that the fraction of UV energy incident on the transparent walls increases with increasing power level. For the reference engine power level of 4600 megw, it is necessary to employ space radiators to reject the UV radiated energy absorbed by the transparent walls. This UV energy can be blocked by employing nitric oxide and oxygen seed gases in the fuel and buffer gas regions. However, this results in increased UV absorption in the buffer gas which also requires space radiators to reject the heat load.

  17. Molecular phylogenetics of subfamily Ornithogaloideae (Hyacinthaceae) based on nuclear and plastid DNA regions, including a new taxonomic arrangement

    PubMed Central

    Martínez-Azorín, Mario; Crespo, Manuel B.; Juan, Ana; Fay, Michael F.

    2011-01-01

    Background and Aims The taxonomic arrangement within subfamily Ornithogaloideae (Hyacinthaceae) has been a matter of controversy in recent decades: several new taxonomic treatments have been proposed, based exclusively on plastid DNA sequences, and these have resulted in classifications which are to a great extent contradictory. Some authors have recognized only a single genus Ornithogalum for the whole subfamily, including 250–300 species of variable morphology, whereas others have recognized many genera. In the latter case, the genera are inevitably much smaller and they are better defined morphologically. However, some are not monophyletic as circumscribed. Methods Phylogenetic analyses of Ornithogaloideae were based on nucleotide sequences of four plastid regions (trnL intron, trnL-F spacer, rbcL and matK) and a nuclear region (ITS). Eighty species covering all relevant taxonomic groups previously recognized in the subfamily were sampled. Parsimony and Bayesian analyses were performed. The molecular data were compared with a matrix of 34 morphological characters. Key Results Combinations of plastid and nuclear data yielded phylogenetic trees which are better resolved than those obtained with any plastid region alone or plastid regions in combination. Three main clades are found, corresponding to the previously recognized tribes Albuceae, Dipcadieae and Ornithogaleae. In these, up to 19 clades are described which are definable by morphology and biogeography. These mostly correspond to previously described taxa, though some need recircumscription. Morphological characters are assessed for their diagnostic value for taxonomy in the subfamily. Conclusions On the basis of the phylogenetic analyses, 19 monophyletic genera are accepted within Ornithogaloideae: Albuca, Avonsera, Battandiera, Cathissa, Coilonox, Dipcadi, Eliokarmos, Elsiea, Ethesia, Galtonia, Honorius, Loncomelos, Melomphis, Neopatersonia, Nicipe, Ornithogalum, Pseudogaltonia, Stellarioides and

  18. Echo Mapping of Active Galactic Nuclei

    NASA Technical Reports Server (NTRS)

    Peterson, B. M.; Horne, K.

    2004-01-01

    Echo mapping makes use of the intrinsic variability of the continuum source in active galactic nuclei to map out the distribution and kinematics of line-emitting gas from its light travel time-delayed response to continuum changes. Echo mapping experiments have yielded sizes for the broad line-emitting region in about three dozen AGNs. The dynamics of the line-emitting gas seem to be dominated by the gravity of the central black hole, enabling measurement of the black-hole masses in AGNs. We discuss requirements for future echo-mapping experiments that will yield the high quality velocity-delay maps of the broad-line region that are needed to determine its physical nature.

  19. RADIS - a regional nuclear accident consequence analysis model for Hong Kong

    SciTech Connect

    Yeung, Mankit Ray; Ching, E.M.K. )

    1993-02-01

    An atmospheric dispersion and consequence model called RADIS has been developed by the University of Hong Kong for nuclear accident consequence analysis. The model uses a two-dimensional plume trajectory derived from wind data for Hong Kong. Dose, health effects, and demographic models are also developed and implemented in RADIS so that accident consequences in 15 major population centers of Greater Hong Kong can be determined individually. In addition, benchmark testing results are give, and comparisons with the analytical solution and CRAC2 results are consistent and satisfactory. Sample calculational results for severe accident consequences are also presented to demonstrate the applicability of RADIS for dry and wet weather conditions.

  20. [Migration in soil and accumulation in plants of peaceful nuclear explosion products in Perm region].

    PubMed

    Raskosha, N G; Shuktova, I I

    2015-01-01

    The data on the migration capacity in soil and accumulation of 238Pu, 239, 240Pu, 137Cs and 90Sr by plants in the area of a peaceful nuclear explosion located in the taiga zone are presented. The influence of the soil parameters on the distribution and transformation forms of the radionuclides in the podzolic soil profile was studied. The major amounts of man-made radionuclides were found in the matter of the ground lip. The accumulation parameters of pollutants by plants were the highest for the leaves, young branches and conifer of trees. PMID:25962279

  1. Probing Galactic 26Al with Exotic Ion Beams

    SciTech Connect

    Chen, Alan A.

    2006-07-12

    The goal of understanding the production of galactic 26Al brings together progress in nuclear astrophysics from observations, theory, meteoritics, and laboratory experiments. In the case of experimental work, nuclear reactions involving unstable isotopes are being studied to elucidate the production of 26Al in stellar explosive nucleosynthesis. We discuss a direct measurement of the 26Al(p,{gamma})27Si reaction with the DRAGON collaboration at TRIUMF, and a measurement of 25Al+p elastic scattering with the CRIB (CNS-U.Tokyo) collaboration, toward constraining the 25Al(p,{gamma})26Si reaction.

  2. Probing Galactic 26Al with Exotic Ion Beams

    NASA Astrophysics Data System (ADS)

    Chen, Alan A.

    2006-07-01

    The goal of understanding the production of galactic 26Al brings together progress in nuclear astrophysics from observations, theory, meteoritics, and laboratory experiments. In the case of experimental work, nuclear reactions involving unstable isotopes are being studied to elucidate the production of 26Al in stellar explosive nucleosynthesis. We discuss a direct measurement of the 26Al(p,γ)27Si reaction with the DRAGON collaboration at TRIUMF, and a measurement of 25Al+p elastic scattering with the CRIB (CNS-U.Tokyo) collaboration, toward constraining the 25Al(p,γ)26Si reaction.

  3. [Comparative Analysis of DNA Sequences of Regions of X-Chromosome Attachment to the Nuclear Envelope of Nurse Cells Anopheles messeae Fall].

    PubMed

    Artemov, G N; Vasil'eva, O Yu; Stegniy, V N

    2015-07-01

    Polytene chromosomes of ovarian nurse cells of Anopheles mosquitoes form strong contacts with the nuclear envelope. The presence of contacts, their position at nurse cell chromosomes, and their morphological features are species-specific in malaria mosquitoes. It is important to determine the nature of these interspecies differences in the nuclear architecture, both to understand the function of the nucleus and to assess the role of the spatial organization of chromosomes in evolution. Using dot-blot hybridization, we compared DNA sequences of the clone library from the X-chromosome attachment region to the nuclear envelope of ovarian nurse cells of Anopheles messeae with DNA-probes: (1) of the X-chromosome attachment region of An. atroparvus, (2) of the 3R chromosome attachment region ofAn. messeae, and (3) of the chromosome 2 pericentromeric region of An. messeae, without expressed contacts with the nuclear envelope. It has been shown that the chromosome attachment regions have a significantly higher number of homologous DNA sequences as compared with the pericentromeric region of chromosome 2. Sequences that are common for attachment regions are largely potentially able to participate in the formation of chromatin loop domains and to interact with some nucleus frameworks, according to the analysis in the ChrClass program. The obtained results support the important role of DNA in the formation of strong chromosomal attachments to the nuclear envelope in nurse cells of Anopheles mosquitoes.

  4. THE GALACTIC PLANE INFRARED POLARIZATION SURVEY (GPIPS)

    SciTech Connect

    Clemens, Dan P.; Pinnick, A. F.; Pavel, M. D.; Taylor, B. W. E-mail: apinnick@bu.edu E-mail: bwtaylor@bu.edu

    2012-06-01

    The scientific motivation, data collection strategy, data reduction, and analysis methods are presented for the Galactic Plane Infrared Polarization Survey (GPIPS). The chief goal for the Survey was to reveal the nature of the magnetic field threading the Galactic disk, in particular through regions of low to moderate extinction (1-20 mag of A{sub V} ) and star formation in the cool interstellar medium. The Survey region spans 76 deg{sup 2} of the northern Milky Way disk, from l = 18 Degree-Sign to 56 Degree-Sign and b =-1 Degree-Sign to +1 Degree-Sign . Linear polarimetric imaging observations began in 2006 in the near-infrared H band (1.6 {mu}m) using the Mimir instrument on the 1.8 m Perkins telescope, located outside Flagstaff, AZ. Mimir used a cold, fixed wire grid and a rotateable cold, compound half-wave plate to obtain 'step-and-integrate' polarimetry over its full 10 Multiplication-Sign 10 arcmin field of view. The GPIPS bright and faint polarimetric limits are approximately 7th and 15th mag, respectively, set by saturation and photon noise. Polarimetric uncertainties track with stellar magnitude, from about 0.1% to 25%, on average, from the brightest to faintest stars. Across the 3237 field GPIPS region, approximately 0.5 million stars are estimated to show detectable linear polarization (P/{sigma}{sub P} > 3); most of these have m{sub H} < 12. This represents many orders of magnitude improvement in the number of polarization measurements across this region. GPIPS observations are more than 90% complete and should finish in 2012.

  5. Far-ultraviolet diffuse galactic light

    NASA Technical Reports Server (NTRS)

    Henry, R. C.

    1981-01-01

    Diffuse galactic light is detected at very low galactic latitudes, and useful upper limits are obtained at moderate and high galactic latitudes. Together, these data indicate that the albedo of the interstellar grains is high (a greater than 0.5) and that the grains very strongly (g greater than 0.7) forward-scatter far-ultraviolet radiation.

  6. Automatic data processing and analysis system for monitoring region around a planned nuclear power plant

    NASA Astrophysics Data System (ADS)

    Kortström, Jari; Tiira, Timo; Kaisko, Outi

    2016-03-01

    The Institute of Seismology of University of Helsinki is building a new local seismic network, called OBF network, around planned nuclear power plant in Northern Ostrobothnia, Finland. The network will consist of nine new stations and one existing station. The network should be dense enough to provide azimuthal coverage better than 180° and automatic detection capability down to ML -0.1 within a radius of 25 km from the site.The network construction work began in 2012 and the first four stations started operation at the end of May 2013. We applied an automatic seismic signal detection and event location system to a network of 13 stations consisting of the four new stations and the nearest stations of Finnish and Swedish national seismic networks. Between the end of May and December 2013 the network detected 214 events inside the predefined area of 50 km radius surrounding the planned nuclear power plant site. Of those detections, 120 were identified as spurious events. A total of 74 events were associated with known quarries and mining areas. The average location error, calculated as a difference between the announced location from environment authorities and companies and the automatic location, was 2.9 km. During the same time period eight earthquakes between magnitude range 0.1-1.0 occurred within the area. Of these seven could be automatically detected. The results from the phase 1 stations of the OBF network indicates that the planned network can achieve its goals.

  7. PREFACE: Astronomy at High Angular Resolution 2011: The central kiloparsec in galactic nuclei

    NASA Astrophysics Data System (ADS)

    Iserlohe, Christof; Karas, Vladimir; Krips, Melanie; Eckart, Andreas; Britzen, Silke; Fischer, Sebastian

    2012-07-01

    We are pleased to present the proceedings from the Astronomy at High Angular Resolution 2011: The central kiloparsec in galactic nuclei conference. The conference took place in the Physikzentrum of the Deutsche Physikalische Gesellschaft (DPG), Bad Honnef, Germany, from 28 August to 2 September 2011. It was the second conference of this kind, following the Astronomy at High Angular Resolution conference held in Bad Honnef, three years earlier in 2008. The main objective of the conference was to frame the discussion of the broad range of physical processes that occur in the central 100pc of galactic nuclei. In most cases, this domain is difficult to probe through observations. This is mainly because of the lack of angular resolution, the brightness of the central engine and possible obscurations through dust and gas, which play together in the central regions of host galaxies of galactic nuclei within a broad range of activity. The presence of large amounts of molecular and atomic (both neutral and ionized) gas, dust and central engines with outflows and jets implies that the conditions for star formation in these regions are very special, and probably different from those in the disks of host galaxies. Numerous presentations covering a broad range of topics, both theoretical and experimental, those related to research on Active Galactic Nuclei and on a wide range of observed wavelengths were submitted to the Scientific Organizing Committee. Presentations have been grouped into six sessions: The nuclei of active galaxies The Galactic Center The immediate environment of Super Massive Black Holes The physics of nuclear jets and the interaction of the interstellar medium The central 100pc of the nuclear environment Star formation in that region The editors thank all participants of the AHAR 2011 conference for their enthusiasm and their numerous and vivid contributions to this conference. We would especially like to thank John Hugh Seiradakis from the Aristotle

  8. Particle acceleration on Galactic scales

    NASA Astrophysics Data System (ADS)

    Axford, W. I.

    The history of and current ideas concerning the origin of cosmic rays in the Galaxy and in extragalactic sources are surveyed. The observed properties of Galactic cosmic rays and shock acceleration are discussed. It is argued that shock acceleration in various guises is an essential and conceptually the most economical acceleration mechanism.

  9. Air Pollution Studies in Tver Region of Russia using Moss-Biomonitoring with Nuclear Analytical Methods

    SciTech Connect

    Vergel, K. N.; Frontasyeva, M. V.; Pavlov, S. S.; Povtoreyko, E. A.

    2007-11-26

    Results of the trace element atmospheric deposition in the Tver region based on moss analysis are presented. Moss samples were collected in the summer of 1999 and 2004 from 174 sites evenly distributed over the region. As bioaccumulators, two common mosses were used: Pleurozium schreberi ({approx}80%) and Hylocomium splendens ({approx}20%). The moss samples were subject to neutron activation analysis at the IBR-2 reactor JINR Dubna. The purpose of this study was to determine deposition patterns of potent sources of air pollution such as the largest Russian thermal power plant nearby the town of Konakovo and to reveal previously unknown pollution sources located in towns and settlements within the sampled territory. Multivariate statistical analysis was applied to determine possible pollution sources over the examined territory. Comparison of the results obtained with those from other surveys in Russia and Europe shows that Tver region could be considered as a background territory for the Russian Federation.

  10. TM6, a novel nuclear matrix attachment region, enhances its flanking gene expression through influencing their chromatin structure.

    PubMed

    Ji, Lusha; Xu, Rui; Lu, Longtao; Zhang, Jiedao; Yang, Guodong; Huang, Jinguang; Wu, Changai; Zheng, Chengchao

    2013-08-01

    Nuclear matrix attachment regions (MARs) regulate the higher-order organization of chromatin and affect the expression of their flanking genes. In this study, a tobacco MAR, TM6, was isolated and demonstrated to remarkably increase the expression of four different promoters that drive gusA gene and adjacent nptII gene. In turn, this expression enhanced the transformation frequency of transgenic tobacco. Deletion analysis of topoisomerase II-binding site, AT-rich element, and MAR recognition signature (MRS) showed that MRS has the highest contribution (61.7%) to the TM6 sequence-mediated transcription activation. Micrococcal nuclease (MNase) accessibility assay showed that 35S and NOS promoter regions with TM6 are more sensitive than those without TM6. The analysis also revealed that TM6 reduces promoter DNA methylation which can affect the gusA expression. In addition, two tobacco chromatin-associated proteins, NtMBP1 and NtHMGB, isolated using a yeast one-hybrid system, specifically bound to the TM6II-1 region (761 bp to 870 bp) and to the MRS element in the TM6II-2 (934 bp to 1,021 bp) region, respectively. We thus suggested that TM6 mediated its chromatin opening and chromatin accessibility of its flanking promoters with consequent enhancement of transcription.

  11. TM6, a novel nuclear matrix attachment region, enhances its flanking gene expression through influencing their chromatin structure.

    PubMed

    Ji, Lusha; Xu, Rui; Lu, Longtao; Zhang, Jiedao; Yang, Guodong; Huang, Jinguang; Wu, Changai; Zheng, Chengchao

    2013-08-01

    Nuclear matrix attachment regions (MARs) regulate the higher-order organization of chromatin and affect the expression of their flanking genes. In this study, a tobacco MAR, TM6, was isolated and demonstrated to remarkably increase the expression of four different promoters that drive gusA gene and adjacent nptII gene. In turn, this expression enhanced the transformation frequency of transgenic tobacco. Deletion analysis of topoisomerase II-binding site, AT-rich element, and MAR recognition signature (MRS) showed that MRS has the highest contribution (61.7%) to the TM6 sequence-mediated transcription activation. Micrococcal nuclease (MNase) accessibility assay showed that 35S and NOS promoter regions with TM6 are more sensitive than those without TM6. The analysis also revealed that TM6 reduces promoter DNA methylation which can affect the gusA expression. In addition, two tobacco chromatin-associated proteins, NtMBP1 and NtHMGB, isolated using a yeast one-hybrid system, specifically bound to the TM6II-1 region (761 bp to 870 bp) and to the MRS element in the TM6II-2 (934 bp to 1,021 bp) region, respectively. We thus suggested that TM6 mediated its chromatin opening and chromatin accessibility of its flanking promoters with consequent enhancement of transcription. PMID:23852133

  12. Rice University observations of the galactic center

    NASA Technical Reports Server (NTRS)

    Meegan, C. A.

    1978-01-01

    The most sensitive of the four balloon fight observations of the galactic center made by Rice University was conducted in 1974 from Rio Cuarto, Argentina at a float altitude of 4 mbar. The count rate spectrum of the observed background and the energy spectrum of the galactic center region are discussed. The detector used consists of a 6 inch Nal(T 1ambda) central detector collimated to approximately 15 deg FWHM by a Nal(T lamdba) anticoincidence shield. The shield in at least two interaction mean free paths thick at all gamma ray energies. The instrumental resolution is approximately 11% FWHM at 662 keV. Pulses from the central detector are analyzed by two 256 channel PHA's covering the energy range approximately 20 keV to approximately 12 MeV. The detector is equatorially mounted and pointed by command from the ground. Observations are made by measuring source and background alternately for 10 minute periods. Background is measured by rotating the detector 180 deg about the azimuthal axis.

  13. The escape model for Galactic cosmic rays

    NASA Astrophysics Data System (ADS)

    Giacinti, G.; Kachelrieß, M.; Semikoz, D. V.

    2015-08-01

    The escape model explains the cosmic ray (CR) knee by energy-dependent CR leakage from the Milky Way, with an excellent fit to all existing data. We test this model calculating the trajectories of individual CRs in the Galactic magnetic field. We find that the CR escape time τesc(E) exhibits a knee-like structure around E/Z = few × 1015 eV for small coherence lengths and strengths of the turbulent magnetic field. The resulting intensities for different groups of nuclei are consistent with the ones determined by KASCADE and KASCADE-Grande, using simple power-laws as injection spectra. The transition from Galactic to extragalactic CRs happens in this model at low energies and is terminated below ≈ 3 × 1018 eV. The intermediate energy region up to the ankle is populated by CRs accelerated in starburst galaxies. This model provides a good fit to ln(A) data, while the estimated CR dipole anisotropy is close to, or below, upper limits in the energy range 1017 - 1018 eV. The phase of the dipole is expected to change between 1 × 1017 and 3 × 1018 eV.

  14. SPI measurements of Galactic 26Al

    NASA Astrophysics Data System (ADS)

    Diehl, R.; Knödlseder, J.; Lichti, G. G.; Kretschmer, K.; Schanne, S.; Schönfelder, V.; Strong, A. W.; von Kienlin, A.; Weidenspointner, G.; Winkler, C.; Wunderer, C.

    2003-11-01

    The precision measurement of the 1809 keV gamma-ray line from Galactic 26Al is one of the goals of the SPI spectrometer on INTEGRAL with its Ge detector camera. We aim for determination of the detailed shape of this gamma-ray line, and its variation for different source regions along the plane of the Galaxy. Data from the first part of the core program observations of the first mission year have been inspected. A clear detection of the 26Al line at =~ 5-7 sigma significance demonstrates that SPI will deepen 26Al studies. The line intensity is consistent with expectations from previous experiments, and the line appears narrower than the 5.4 keV FWHM reported by GRIS, more consistent with RHESSI's recent value. Only preliminary statements can be made at this time, however, due to the multi-component background underlying the signal at =~ 40 times higher intensity than the signal from Galactic 26Al.

  15. Automatic data processing and analysis system for monitoring region around a planned nuclear power plant

    NASA Astrophysics Data System (ADS)

    Tiira, Timo; Kaisko, Outi; Kortström, Jari; Vuorinen, Tommi; Uski, Marja; Korja, Annakaisa

    2015-04-01

    The site of a new planned nuclear power plant is located in Pyhäjoki, eastern coast of the Bay of Bothnia. The area is characterized by low-active intraplate seismicity, with earthquake magnitudes rarely exceeding 4.0. IAEA guidelines state that when a nuclear power plant site is evaluated a network of sensitive seismographs having a recording capability for micro-earthquakes should be installed to acquire more detailed information on potential seismic sources. The operation period of the network should be long enough to obtain a comprehensive earthquake catalogue for seismotectonic interpretation. A near optimal configuration of ten seismograph stations will be installed around the site. A central station, including 3-C high-frequency and strong motion seismographs, is located in the site area. In addition, the network comprises nine high-frequency 3-C stations within a distance of 50 km from the central station. The network is dense enough to fulfil the requirements of azimuthal coverage better than 180o and automatic event location capability down to ~ ML -0.1 within a radius of 25 km from the site. Automatic processing and analysis of the planned seismic network is presented. Following the IAEA guidelines, real-time monitoring of the site area is integrated with the automatic detection and location process operated by the Institute of Seismology, University of Helsinki. In addition interactive data analysis is needed. At the end of year 2013 5 stations have been installed. The automatic analysis utilizes also 7 near by stations of national seismic networks of Finland and Sweden. During this preliminary phase several small earthquakes have been detected. The detection capability and location accuracy of the automatic analysis is estimated using chemical explosions at 15 known sites.

  16. LLNL's Regional Model Calibration and Body-Wave Discrimination Research in the Former Soviet Union using Peaceful Nuclear Explosions (PNEs)

    SciTech Connect

    Bhattacharyya, J.; Rodgers, A.; Swenson, J.; Schultz, C.; Walter, W.; Mooney, W.; Clitheroe, G.

    2000-07-14

    Long-range seismic profiles from Peaceful Nuclear Explosions (PNE) in the Former Soviet Union (FSU) provide a unique data set to investigate several important issues in regional Comprehensive Nuclear-Test-Ban Treaty (CTBT) monitoring. The recording station spacing ({approx}15 km) allows for extremely dense sampling of the propagation from the source to {approx} 3300 km. This allows us to analyze the waveforms at local, near- and far-regional and teleseismic distances. These data are used to: (1) study the evolution of regional phases and phase amplitude ratios along the profile; (2) infer one-dimensional velocity structure along the profile; and (3) evaluate the spatial correlation of regional and teleseismic travel times and regional phase amplitude ratios. We analyzed waveform data from four PNE's (m{sub b} = 5.1-5.6) recorded along profile KRATON, which is an east-west trending profile located in northern Sibertil. Short-period regional discriminants, such as P/S amplitude ratios, will be essential for seismic monitoring of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) at small magnitudes (m{sub b} < 4.0). However, P/S amplitude ratios in the short-period band, 0.5-5.0 Hz, show some scatter. This scatter is primarily due to propagation and site effects, which arise from variability in the elastic and anelastic structure of the crustal waveguide. Preliminary results show that Pg and Lg propagate efficiently in north Siberia at regional distances. The amplitude ratios show some variability between adjacent stations that are modeled by simple distance trends. The effect of topography, sediment and crustal thickness, and upper mantle discontinuities on these ratios, after removal of the distance trends, will be investigated. The travel times of the body wave phases recorded on KEATON have been used to compute the one-dimensional structure of the crust and upper mantle in this region. The path-averaged one-dimensional velocity model was computed by minimizing the

  17. The Molecular H2 Emission and the Stellar Kinematics in the Nuclear Region of the Sombrero Galaxy

    NASA Astrophysics Data System (ADS)

    Menezes, R. B.; Steiner, J. E.

    2015-07-01

    We analyze the molecular H2 emission and the stellar kinematics in a data cube of the nuclear region of M104, the Sombrero galaxy, obtained with NIFS on the Gemini-north telescope. After a careful subtraction of the stellar continuum, the only emission line we detected in the data cube was {{{H}}}2λ 21218. An analysis of this emission revealed the existence of a rotating molecular torus/disk, aproximately co-planar with a dusty structure detected by us in a previous work. We interpret these two structures as being associated with the same obscuring torus/disk. The kinematic maps provided by the Penalized Pixel Fitting method revealed that the stellar kinematics in the nuclear region of M104 appears to be the result of the superposition of a “cold” rotating disk and a “hot” bulge. Using a model of a thin eccentric disk, we reproduced the main properties of the maps of the stellar radial velocity and of the stellar velocity dispersion, especially within a distance of 0\\prime\\prime .2 from the kinematic axis (in regions at larger distances, the limitations of a model of a thin rotating disk become more visible). The general behavior of the h3 map, which is significantly noisier than the other maps, was also reproduced by our model (although the discrepancies, in this case, are considerably higher). With our model, we obtained a mass of (9.0+/- 2.0)× {10}8{M}⊙ for the supermassive black hole of M104, which is compatible, at 1σ or 2σ levels, with the values obtained by previous studies.

  18. Studying Galactic interstellar turbulence through fluctuations in synchrotron emission. First LOFAR Galactic foreground detection

    NASA Astrophysics Data System (ADS)

    Iacobelli, M.; Haverkorn, M.; Orrú, E.; Pizzo, R. F.; Anderson, J.; Beck, R.; Bell, M. R.; Bonafede, A.; Chyzy, K.; Dettmar, R.-J.; Enßlin, T. A.; Heald, G.; Horellou, C.; Horneffer, A.; Jurusik, W.; Junklewitz, H.; Kuniyoshi, M.; Mulcahy, D. D.; Paladino, R.; Reich, W.; Scaife, A.; Sobey, C.; Sotomayor-Beltran, C.; Alexov, A.; Asgekar, A.; Avruch, I. M.; Bell, M. E.; van Bemmel, I.; Bentum, M. J.; Bernardi, G.; Best, P.; Bırzan, L.; Breitling, F.; Broderick, J.; Brouw, W. N.; Brüggen, M.; Butcher, H. R.; Ciardi, B.; Conway, J. E.; de Gasperin, F.; de Geus, E.; Duscha, S.; Eislöffel, J.; Engels, D.; Falcke, H.; Fallows, R. A.; Ferrari, C.; Frieswijk, W.; Garrett, M. A.; Grießmeier, J.; Gunst, A. W.; Hamaker, J. P.; Hassall, T. E.; Hessels, J. W. T.; Hoeft, M.; Hörandel, J.; Jelic, V.; Karastergiou, A.; Kondratiev, V. I.; Koopmans, L. V. E.; Kramer, M.; Kuper, G.; van Leeuwen, J.; Macario, G.; Mann, G.; McKean, J. P.; Munk, H.; Pandey-Pommier, M.; Polatidis, A. G.; Röttgering, H.; Schwarz, D.; Sluman, J.; Smirnov, O.; Stappers, B. W.; Steinmetz, M.; Tagger, M.; Tang, Y.; Tasse, C.; Toribio, C.; Vermeulen, R.; Vocks, C.; Vogt, C.; van Weeren, R. J.; Wise, M. W.; Wucknitz, O.; Yatawatta, S.; Zarka, P.; Zensus, A.

    2013-10-01

    Aims: The characteristic outer scale of turbulence (i.e. the scale at which the dominant source of turbulence injects energy to the interstellar medium) and the ratio of the random to ordered components of the magnetic field are key parameters to characterise magnetic turbulence in the interstellar gas, which affects the propagation of cosmic rays within the Galaxy. We provide new constraints to those two parameters. Methods: We use the LOw Frequency ARray (LOFAR) to image the diffuse continuum emission in the Fan region at (l,b) ~ (137.0°, +7.0°) at 80'' × 70'' resolution in the range [146, 174] MHz. We detect multi-scale fluctuations in the Galactic synchrotron emission and compute their power spectrum. Applying theoretical estimates and derivations from the literature for the first time, we derive the outer scale of turbulence and the ratio of random to ordered magnetic field from the characteristics of these fluctuations. Results: We obtain the deepest image of the Fan region to date and find diffuse continuum emission within the primary beam. The power spectrum displays a power law behaviour for scales between 100 and 8 arcmin with a slope α = -1.84 ± 0.19. We find an upper limit of ~20 pc for the outer scale of the magnetic interstellar turbulence toward the Fan region, which is in agreement with previous estimates in literature. We also find a variation of the ratio of random to ordered field as a function of Galactic coordinates, supporting different turbulent regimes. Conclusions: We present the first LOFAR detection and imaging of the Galactic diffuse synchrotron emission around 160 MHz from the highly polarized Fan region. The power spectrum of the foreground synchrotron fluctuations is approximately a power law with a slope α ≈ -1.84 up to angular multipoles of ≲1300, corresponding to an angular scale of ~8 arcmin. We use power spectra fluctuations from LOFAR as well as earlier GMRT and WSRT observations to constrain the outer scale of

  19. ACTIVITY IN GALACTIC NUCLEI OF COMPACT GROUP GALAXIES IN THE LOCAL UNIVERSE

    SciTech Connect

    Sohn, Jubee; Lee, Myung Gyoon; Lee, Gwang-Ho; Hwang, Ho Seong; Lee, Jong Chul E-mail: mglee@astro.snu.ac.kr E-mail: hhwang@cfa.harvard.edu

    2013-07-10

    We study the nuclear activity of galaxies in local compact groups. We use a spectroscopic sample of 238 galaxies in 58 compact groups from the Sloan Digital Sky Survey data release 7 to estimate the fraction of active galactic nucleus (AGN) host galaxies in compact groups, and to compare it with those in cluster and field regions. We use emission-line ratio diagrams to identify AGN host galaxies and find that the AGN fraction of compact group galaxies is 17%-42% depending on the AGN classification method. The AGN fraction in compact groups is not the highest among the galaxy environments. This trend remains even if we use several subsamples segregated by galaxy morphology and optical luminosity. The AGN fraction for early-type galaxies decreases with increasing galaxy number density, but the fraction for late-type galaxies changes little. We find no mid-infrared detected AGN host galaxies in our sample of compact groups using Wide-field Infrared Survey Explorer data. These results suggest that the nuclear activity of compact group galaxies (mostly early types) is not strong because of lack of gas supply even though they may experience frequent galaxy-galaxy interactions and mergers that could trigger nuclear activity.

  20. Galactic X-rays: Variable Sources in Hydromagnetic Waves.

    PubMed

    Lelevier, R E; Libby, L M

    1968-06-28

    Galactic sources of x-rays fluctuating in intensity are explained as being small regions, of enhanced gas density and temperature, emitting thermal Coulomb bremsstrahlung of kiloelectron-volt energies. Hydromagnetic wave motions, of the magnetic fields in the galactic spiral arms, produce the enhanced regions by compressing the clouds of ionized gas to which they are tied by their high electrical conductivity. From the observed periods of fluctuation of a few months, together with the hydromagnetic velocity, it is estimated that the average size of sources does not exceed 10(16) centimeters. By using the formula for Coulomb bremsstrahlung and requiring that the sources shall produce the observed x-ray fluxes, one finds a second estimate of size of sources in agreement at about 1016 centimeters. Such regions are too small to be observable radio sources with current radio telescopes.

  1. Characterization of amino acid residues within the N-terminal region of Ubc9 that play a role in Ubc9 nuclear localization

    SciTech Connect

    Sekhri, Palak; Tao, Tao; Kaplan, Feige; Zhang, Xiang-Dong

    2015-02-27

    As the sole E2 enzyme for SUMOylation, Ubc9 is predominantly nuclear. However, the underlying mechanisms of Ubc9 nuclear localization are still not well understood. Here we show that RNAi-depletion of Imp13, an importin known to mediate Ubc9 nuclear import, reduces both Ubc9 nuclear accumulation and global SUMOylation. Furthermore, Ubc9-R13A or Ubc9-H20D mutation previously shown to interrupt the interaction of Ubc9 with nucleus-enriched SUMOs reduces the nuclear enrichment of Ubc9, suggesting that the interaction of Ubc9 with the nuclear SUMOs may enhance Ubc9 nuclear retention. Moreover, Ubc9-R17E mutation, which is known to disrupt the interaction of Ubc9 with both SUMOs and Imp13, causes a greater decrease in Ubc9 nuclear accumulation than Ubc9-R13A or Ubc9-H20D mutation. Lastly, Ubc9-K74A/S89D mutations that perturb the interaction of Ubc9 with nucleus-enriched SUMOylation-consensus motifs has no effect on Ubc9 nuclear localization. Altogether, our results have elucidated that the amino acid residues within the N-terminal region of Ubc9 play a pivotal role in regulation of Ubc9 nuclear localization. - Highlights: • Imp13-mediated nuclear import of Ubc9 is critical for global SUMOylation. • Ubc9 mutations disrupting Ubc9-SUMO interaction decrease Ubc9 nuclear accumulation. • N-terminal amino acid residues of Ubc9 are critical for Ubc9 nuclear enrichment.

  2. Genomewide identification of nuclear matrix attachment regions: an analysis of methods.

    PubMed

    Linnemann, A K; Platts, A E; Doggett, N; Gluch, A; Bode, J; Krawetz, S A

    2007-06-01

    High-throughput technologies now afford the opportunity to directly determine the distribution of MARs (matrix attachment regions) throughout a genome. The utility of cosmid and oligonucleotide platforms to identify human chromosome 16 MARs from preparations that employed LIS (lithium di-iodosalicylic acid) and NaCl extraction protocols was examined. The effectiveness of the platforms was then evaluated by Q-PCR (quantitative real-time PCR). Analysis revealed that caution must be exercised, since the representation of non-coding regions varies among platforms. Nevertheless, several interesting trends were revealed. We expect that these technologies will prove useful in systems approaches directed towards defining the role of MARs in various cell types and cellular processes.

  3. Nuclear structure in the neutron-rich doubly magic sup 78 Ni region

    SciTech Connect

    Hill, J.C.; Wohn, F.K.; Winger, J.A.; Warburton, E.K.; Gill, R.L.; Schuhmann, R.B.; Brookhaven National Lab., Upton, NY; Clark Univ., Worcester, MA )

    1989-01-01

    The magic numbers Z=28 and N=50 imply that very neutron-rich {sup 78}Ni, which has not yet been observed, is doubly magic. The {sup 78}Ni region was investigated by studying the N=50 isotones and neutron-rich Zn isotopes. Results on the level structure of {sup 83}As, {sup 74}Zn, and {sup 76}Zn populated in the decays of {sup 83}Ge, {sup 74}Cu, and {sup 76}Cu are presented. The parent nuclides were produced and mass separated using the TRISTAN facility on-line to the High-Flux Beam Reactor at Brookhaven. The systematics of the N=50 isotones and even-A Zn isotopes are discussed and compared with shell-model calculations involving active nucleons outside of a {sup 78}Ni and {sup 66}Ni core, respectively. The extent to which the {sup 78}Ni region can be considered doubly magic is assessed. 43 refs., 7 figs.

  4. Radon measurements by nuclear track detectors in secondary schools in Oke-Ogun region, Nigeria.

    PubMed

    Obed, R I; Ademola, A K; Vascotto, M; Giannini, G

    2011-11-01

    Radon measurements were performed in secondary schools in the Oke-Ogun area, South-west, Nigeria, by solid state nuclear track detectors (SSNTDs). About seventy CR-39 detectors were distributed in 35 high schools of the Oke-Ogun area. The CR-39 detectors were exposed in the schools for 3 months and then etched in NaOH 6 N solution at 90 °C for 3 h. The tracks were counted manually at the microscope and the radon concentration was determined at the Radioactivity Laboratory, Department of Physics, University of Trieste, Trieste, Italy. The overall average radon concentration in the surveyed area was 45 ± 27 Bq m(-3). The results indicate no radiological health hazard. The research also focused on parameters affecting radon concentrations such as the age of the building in relation to building materials and floor number of the classrooms. The results show that radon concentrations in ground floors are higher than in upper floors.

  5. Nuclear Structure Investigations of Neutron Deficient Nuclei in the Region Z = 103 to 105

    SciTech Connect

    Heberger, F.P.; Hofmann, S.; Ackermann, D.; Armbruster, P.; Munzenberg, G.; Stodel, Ch.; Lavrentev, A.Yu.; Popeko, A.G.; Yeremin, A.V.; Saro, S.; Leino, M.

    1999-12-31

    The isotopes {sup 257,255}Rf, {sup 257,256}Db, {sup 253,252}Lr have been produced in bombardments of {sup 207,208}Pb and {sup 209}Bi target nuclei with {sup 50}Ti and identified by their {alpha}-decay. New or improved decay data could be obtained. Analysis of the fine structure of the {alpha}-decay pattern of {sup 257}Rf allowed the construction of a first tentative level scheme for the daughter nucleus {sup 253}No and also the identification of a low lying high spin isomeric state, while from {alpha}-{gamma} coincidence measurements for {sup 255}Rf a first tentative level scheme of the daughter nucleus {sup 251}No was derived. For {sup 257}Db we found that two nuclear levels decay by {alpha}-emission and populate also different levels in the daughter nucleus {sup 253}Lr. The levels are produced by the reaction process. In bombardments of {sup 209}Bi with {sup 50}Ti at E*{sub cn} = 26.4 MeV and 30.8 MeV the previously unknown isotopes {sup 256}Db and {sup 22}Lr were identified.

  6. Nuclear structure investigations of neutron deficient nuclei in the region Z=103 to 105

    SciTech Connect

    Hessberger, F. P.; Hofmann, S.; Armbruster, P.; Muenzenberg, G.; Stodel, Ch.; Ackermann, D.; Lavrentev, A. Yu.; Popeko, A. G.; Yeremin, A. V.; Saro, S.; Leino, M.

    1999-11-16

    The isotopes {sup 257,255}Rf, {sup 257,256}Db, {sup 253,252}Lr have been produced in bombardments of {sup 207,208}Pb and {sup 209}Bi target nuclei with {sup 50}Ti and identified by their {alpha}-decay. New or improved decay data could be obtained. Analysis of the fine structure of the {alpha}-decay pattern of {sup 257}Rf allowed the construction of a first tentative level scheme for the daughter nucleus {sup 253}No and also the identification of a low lying high spin isomeric state, while from {alpha}-{gamma}- coincidence measurements for {sup 255}Rf a first tentative level scheme of the daughter nucleus {sup 251}No was derived. For {sup 257}Db we found that two nuclear levels decay by {alpha}-emission and populate also different levels in the daughter nucleus {sup 253}Lr. The levels are produced by the reaction process. In bombardments of {sup 209}Bi with {sup 50}Ti at E{sub CN}*=26.4 MeV and 30.8 MeV the previously unknown isotopes {sup 256}Db and {sup 252}Lr were identified.

  7. 2011 Fukushima Dai-ichi nuclear power plant accident: summary of regional radioactive deposition monitoring results.

    PubMed

    Hirose, Katsumi

    2012-09-01

    After the Great East Japan Earthquake and resulting Tsunami on March 11, 2011, serious accident of the Fukushima Dai-ichi Nuclear Power Plant has been occurred. Huge amounts of radionuclides were released in atmosphere and ocean. Japanese prefectural governments have carried out environmental radioactivity monitoring; external dose rate, radioactivity measurements in environmental samples and others. Since March 18, 2011, daily and monthly deposition samples were collected in 45 stations covering Japanese Islands and radionuclides in the deposition samples were determined. We summarize radioactive deposition data reported by Japanese Government and study the depositional behaviors of the Fukushima-derived radionuclides. The results revealed that Fukushima-derived radioactive cloud dominantly affected in the central and eastern part of Honshu-Island, although it affected all of Japanese land area and also western North Pacific. The temporal change of the Fukushima-derived (137)Cs revealed that the apparent atmospheric residence time of the Fukushima-derived (137)Cs in sites within 300 km from the Fukushima Dai-ichi NPPis about 10 d.

  8. Galaxy interactions and the stimulation of nuclear activity

    NASA Technical Reports Server (NTRS)

    Heckman, Timothy M.

    1990-01-01

    The author discusses the idea that interactions between galaxies can lead to enhanced galactic activity. He discusses whether, apart from the observational evidence, there is a strong theoretical or heuristic motivation for investigating galaxy interactions as stimulators of nuclear activity in galaxies. Galactic interactions as mechanisms for triggering nuclear starbursts are covered.

  9. [Cytologic study of glandular tumors in maxillofacial regions-- diagnostic application of nuclear DNA content].

    PubMed

    Kawasaki, T; Kimura, H; Shingaki, S; Saito, R; Nakajima, T; Mizutani, H; Mori, M; Ishiki, T

    1983-12-01

    We studied whether the DNA contents may be useful in the differential diagnosis of glandular tumors in the maxillofacial regions. In 25 of these tumors, the DNA contents were measured by microspectrophotometry, using 4 normal salivary glands as controls. We found that: (1) DNA histgram patterns were useful in differential diagnosis only in special cases. (2) The criteria were based on our decision and these tumors were classified into 3 types (a) Benign, (b) Low-grade malignant, (c) High-grade malignant. Our classification seemed to offer an objective means for differentiating between Benign & Malignant tumors of these types.

  10. Phylogenetic Analysis of a 'Jewel Orchid' Genus Goodyera (Orchidaceae) Based on DNA Sequence Data from Nuclear and Plastid Regions.

    PubMed

    Hu, Chao; Tian, Huaizhen; Li, Hongqing; Hu, Aiqun; Xing, Fuwu; Bhattacharjee, Avishek; Hsu, Tianchuan; Kumar, Pankaj; Chung, Shihwen

    2016-01-01

    A molecular phylogeny of Asiatic species of Goodyera (Orchidaceae, Cranichideae, Goodyerinae) based on the nuclear ribosomal internal transcribed spacer (ITS) region and two chloroplast loci (matK and trnL-F) was presented. Thirty-five species represented by 132 samples of Goodyera were analyzed, along with other 27 genera/48 species, using Pterostylis longifolia and Chloraea gaudichaudii as outgroups. Bayesian inference, maximum parsimony and maximum likelihood methods were used to reveal the intrageneric relationships of Goodyera and its intergeneric relationships to related genera. The results indicate that: 1) Goodyera is not monophyletic; 2) Goodyera could be divided into four sections, viz., Goodyera, Otosepalum, Reticulum and a new section; 3) sect. Reticulum can be further divided into two subsections, viz., Reticulum and Foliosum, whereas sect. Goodyera can in turn be divided into subsections Goodyera and a new subsection.

  11. THE CHANDRA HRC VIEW OF THE SUBARCSECOND STRUCTURES IN THE NUCLEAR REGION OF NGC 1068

    SciTech Connect

    Wang Junfeng; Fabbiano, Giuseppina; Karovska, Margarita; Elvis, Martin; Risaliti, Guido

    2012-09-10

    We have obtained a high spatial resolution X-ray image of the nucleus of NGC 1068 using the High Resolution Camera (HRC-I) on board the Chandra X-ray Observatory, which provides an unprecedented view of the innermost 1 arcsec radius region of this galaxy. The HRC image resolves the narrow-line region into X-ray emission clumps matching bright emission-line clouds in the HST [OIII] {lambda}5007 images and allows comparison with subarcsecond-scale radio jet for the first time. Two distinct X-ray knots are revealed at 1.3-1.4 arcsec northeast and southwest of the nucleus. Based on the combined X-ray, [O III], and radio continuum morphology, we identify the locations of intense radio jet-cloud interaction. The [O III] to soft X-ray ratios show that some of these clouds are strongly affected by shock heating, whereas in other locations the jet simply thrusts through with no signs of strong interaction. This is further strengthened by the presence of a kT {approx} 1 keV collisionally ionized component in the ACIS spectrum of a shock-heated cloud HST-G. We estimate that the kinematic luminosity of the jet-driven shocks is 6 Multiplication-Sign 10{sup 38} erg s{sup -1}, a negligible fraction (10{sup -4}) of the estimated total jet power.

  12. Nuclear Structure Studies with Radioactive Ion Beams in the Mass A = 80 Region

    SciTech Connect

    Galindo-Uribarri, Alfredo {nmn}; Padilla, E.; Beene, James R; Lagergren, Karin B; Mueller, Paul Edward; Radford, David C; Stracener, Daniel W; Urrego-Blanco, J. P.; Varner Jr, Robert L; Yu, Chang-Hong

    2009-01-01

    An experimental program to measure spectroscopic properties of neutron-rich nuclei in the A = 80 region is underway at the Holifield Radioactive Ion Beam Facility. Our approach has been to get a comprehensive picture of the shell structure in this region by studying a series of properties of low lying states (E (2+), B (E2), g-factors and quadrupole moments). The beams, instrumentation and techniques developed specifically for this purpose have allowed us to systematically study the behavior of these observables along isotopic and isotonic chains using both stable and radioactive nuclei under almost identical experimental conditions. We have developed many techniques and detectors for in-beam gamma spectroscopy and decay studies with radioactive ion beams. Most of the detectors can be used individually or in combination. Generally these detector systems have very large efficiencies. We give examples of their use from three recent experiments; namely, Coulomb excitation of n-rich nuclei along the N = 50 shell closure, the static quadrupole moment of the first 2+ in 78Ge and g-factor measurements of n-rich isotopes near N = 50.

  13. First regional evaluation of nuclear genetic diversity and population structure in northeastern coyotes ( Canis latrans).

    PubMed

    Monzón, Javier

    2014-01-01

    Previous genetic studies of eastern coyotes ( Canis latrans) are based on one of two strategies: sampling many individuals using one or very few molecular markers, or sampling very few individuals using many genomic markers. Thus, a regional analysis of genetic diversity and population structure in eastern coyotes using many samples and several molecular markers is lacking. I evaluated genetic diversity and population structure in 385 northeastern coyotes using 16 common single nucleotide polymorphisms (SNPs). A region-wide analysis of population structure revealed three primary genetic populations, but these do not correspond to the same three subdivisions inferred in a previous analysis of mitochondrial DNA sequences. More focused geographic analyses of population structure indicated that ample genetic structure occurs in coyotes from an intermediate contact zone where two range expansion fronts meet. These results demonstrate that genotyping several highly heterozygous SNPs in a large, geographically dense sample is an effective way to detect cryptic population genetic structure. The importance of SNPs in studies of population and wildlife genomics is rapidly increasing; this study adds to the growing body of recent literature that demonstrates the utility of SNPs ascertained from a model organism for evolutionary inference in closely related species.

  14. First regional evaluation of nuclear genetic diversity and population structure in northeastern coyotes ( Canis latrans)

    PubMed Central

    Monzón, Javier

    2014-01-01

    Previous genetic studies of eastern coyotes ( Canis latrans) are based on one of two strategies: sampling many individuals using one or very few molecular markers, or sampling very few individuals using many genomic markers. Thus, a regional analysis of genetic diversity and population structure in eastern coyotes using many samples and several molecular markers is lacking. I evaluated genetic diversity and population structure in 385 northeastern coyotes using 16 common single nucleotide polymorphisms (SNPs). A region-wide analysis of population structure revealed three primary genetic populations, but these do not correspond to the same three subdivisions inferred in a previous analysis of mitochondrial DNA sequences. More focused geographic analyses of population structure indicated that ample genetic structure occurs in coyotes from an intermediate contact zone where two range expansion fronts meet. These results demonstrate that genotyping several highly heterozygous SNPs in a large, geographically dense sample is an effective way to detect cryptic population genetic structure. The importance of SNPs in studies of population and wildlife genomics is rapidly increasing; this study adds to the growing body of recent literature that demonstrates the utility of SNPs ascertained from a model organism for evolutionary inference in closely related species. PMID:25075291

  15. First regional evaluation of nuclear genetic diversity and population structure in northeastern coyotes ( Canis latrans).

    PubMed

    Monzón, Javier

    2014-01-01

    Previous genetic studies of eastern coyotes ( Canis latrans) are based on one of two strategies: sampling many individuals using one or very few molecular markers, or sampling very few individuals using many genomic markers. Thus, a regional analysis of genetic diversity and population structure in eastern coyotes using many samples and several molecular markers is lacking. I evaluated genetic diversity and population structure in 385 northeastern coyotes using 16 common single nucleotide polymorphisms (SNPs). A region-wide analysis of population structure revealed three primary genetic populations, but these do not correspond to the same three subdivisions inferred in a previous analysis of mitochondrial DNA sequences. More focused geographic analyses of population structure indicated that ample genetic structure occurs in coyotes from an intermediate contact zone where two range expansion fronts meet. These results demonstrate that genotyping several highly heterozygous SNPs in a large, geographically dense sample is an effective way to detect cryptic population genetic structure. The importance of SNPs in studies of population and wildlife genomics is rapidly increasing; this study adds to the growing body of recent literature that demonstrates the utility of SNPs ascertained from a model organism for evolutionary inference in closely related species. PMID:25075291

  16. Meso-diencephalic regions projecting to spinal cord and dorsal column nuclear complex in the hedgehog-tenrec, Echinops telfairi.

    PubMed

    Künzle, H

    1992-01-01

    The distribution of neurons projecting to the spinal cord and dorsal column nuclear complex was investigated in the mesodiencephalic regions of the lesser hedgehog-tenrec, Echinops telfairi (Insectivora) by using the retrograde flow technique. While only few neurons projected to the dorsal column nuclear complex, numerous cells were found to give rise to spinal projections. Rubro-spinal neurons of various sizes were distributed over the entire rostrocaudal extent of the contra-lateral nucleus; a few neurons were also located ipsilaterally, Unlike that of the opossum, the projection appeared to be somatotopically organised. Interstitio-spinal neurons were differentiated into several subpopulations according to their location and laterality of projection. In the ipsilateral periventricular grey, in addition, there was a distinct population of cells possibly corresponding to the nucleus of Darkschewitsch. The mesencephalic central grey contained relatively few labeled neurons, the great majority of them being mesencephalic trigeminal, ectopic cuneiform or midline cells. Labeled cuneiform and midline cells, on the other hand, were quite numerous, extending both from a level just caudal to the trochlear nucleus to levels far beyond the rostral tip of the somatic oculomotor nucleus. The discrepancy between the poorly differentiated oculomotor nuclei and the apparently well-developed Edinger-Westphal complex is discussed. Hypothalamo-spinal neurons were essentially restricted to dorsal regions: the hypothalamic paraventricular nucleus (PAV), the dorso-medial (DmHy) and dorso-intermediate cell groups as well as the lateral hypothalamic zone. The latter two cell groups were bilaterally labeled, while the labeled neurons in DmHy and PAV were located predominantly ipsilaterally. Labeled neurons in the amygdala, colliculus superior and mesencephalic trigeminal nucleus were only found following cervical injections; all other mentioned areas and the posterior commissure complex

  17. Rules of behavior for galactic warps

    SciTech Connect

    Briggs, F.H. Pittsburgh Univ., PA )

    1990-03-01

    An analysis conducted for 12 galaxies with extended, warped H I disks in a variety of reference frames has led to the formulation of clear empirical criteria for galactic warp behavior. In view of these criteria, it emerges that while the H I layer is typically planar within R(25), warping becomes detectable within R(26.5); this is consistent with a straight line of the nodes (LON) measured in the plane defined by the innermost regions of the galaxies. At radii larger than R(26.5), the LON measured in the plane of the inner galaxy advances in the direction of galaxy rotation for successively larger radii. The nodes will accordingly lie along leading spirals in this frame of reference. 32 refs.

  18. Galactic TeV observations with HAWC

    NASA Astrophysics Data System (ADS)

    Hui, Chiumun Michelle

    2014-08-01

    The High Altitude Water Cherenkov (HAWC) Observatory is a gamma-ray and cosmic-ray detector currently under construction at the Sierra Negra volcano in the state of Puebla, Mexico. The full array will consist of 300 water Cherenkov detectors, which contain 1200 photomultiplier tubes and cover an area of 22,000m^2. It has an instantaneous field of view of 2sr, a duty cycle >90%, and is sensitive to energies between 100 GeV and 100 TeV. Data taking began in Summer 2013 with a partial array. I will present the results of HAWC observations of the Galactic plane, which include the complex Cygnus region, and other extended TeV objects with unidentified source associations.

  19. Apollo galactic X-ray astronomy observations

    NASA Technical Reports Server (NTRS)

    Adler, I.; Trombka, J.; Schmadebeck, R.; Gorenstein, P.; Bjorkholm, P.

    1971-01-01

    The galactic X-ray observations are a detailed study of the temporal behavior of pulsating X-ray sources. NASA's first X-ray astronomy satellite Uhuru (Explorer 42) has recently discovered fast time variability of pulsations in the output from several sources. The variability occurs on a time scale of minutes, seconds, or less, implying that the emitting regions are very small in size, much smaller than the sun, although they are emitting about a thousand times more power. Fast time variability may provide the clue that is needed to understand the mechanisms which drive pulsating sources. The Apollo observations record the emission from several objects continuously for a period of about an hour. The spacecraft can be pointed at the source for the entire time. On the other hand, Uhuru can observe only for about a minute or two per sighting. Consequently, Apollo has the capability for determining whether periodicities exist in the 10-1000 second range.

  20. Forming Binary Black Holes in Galactic Mergers

    NASA Astrophysics Data System (ADS)

    Quinn, Thomas R.; Roskar, R.; Mayer, L.; Kazantzidis, S.

    2010-01-01

    As galaxies merge in the standard hierarchical scenario of galaxy formation, their central Black Holes also can merge and grow. The violent dynamics of the galaxy merger will deliver a significant amount of gas and stars to the central regions of the galaxy further growing the central Black Hole and fueling an Active Galactic Nucleus. We perform state-of-art numerical simulations of this merging process using N-body simulations and gas dynamics. These simulations resolved the dynamics in the central kiloparsec of the merging galaxies, and enable us to follow the sinking of the Black Holes to the center via dynamical friction up to the formation of binary Black Holes. Critical to this process is the state of the surrounding gas which we follow with an equation of state that includes star formation and supernova feedback. This work is supported by a grant from NASA.

  1. Photometric reverberation mapping of active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Ramolla, M.; Pozo, F.; Westhues, C.; Haas, M.; Chini, R.; Steenbrugge, K.; Lemke, R.; Murphy, M.

    2014-12-01

    Photometric reverberation mapping is a novel method used to determine the size and geometry of the broad line region (BLR) in active galactic nuclei (AGN) as well as their host galaxy free luminosities. Establishing a tight luminosity - BLR-size relation may allow type-1 AGN to be used as cosmological distance probes. However, the quality of the results is most sensible to dense time sampling and continuity of the photometric lightcurves. This demands an observatory, with optimal environmental conditions, like the "Universitätssternwarte Bochum", located in the Atacama Desert in Chile. The massive amount of observations are controlled robotically, adapting observational schedules of the telescopes to the weather conditions. Here we present one of the first promising results of our studies.

  2. Shielding against galactic cosmic rays

    NASA Technical Reports Server (NTRS)

    Schimmerling, W.; Wilson, J. W.; Nealy, J. E.; Thibeault, S. A.; Cucinotta, F. A.; Shinn, J. L.; Kim, M.; Kiefer, R.

    1996-01-01

    Ions of galactic origin are modified but not attenuated by the presence of shielding materials. Indeed, the number of particles and the absorbed energy behind most shield materials increases as a function of shield thickness. The modification of the galactic cosmic ray composition upon interaction with shielding is the only effective means of providing astronaut protection. This modification is intimately conntected with the shield transport porperties and is a strong function of shield composition. The systematic behavior of the shield properites in terms of microscopic energy absorption events will be discussed. The shield effectiveness is examined with respect to convectional protection practice and in terms of a biological endpoint: the efficiency for reduction of the probability of transformation of shielded C3H1OT1/2 mouse cells. The relative advantage of developing new shielding technologies is discussed in terms of a shield performance as related to biological effect and the resulting uncertainty in estimating astronaut risk.

  3. Inversions for axisymmetric galactic disks

    NASA Astrophysics Data System (ADS)

    Hiotelis, N.; Patsis, P. A.

    1993-08-01

    We use two models for the distribution function to solve an inverse problem for axisymmetric disks. These systems may be considered - under certain assumptions - as galactic disks. In some cases the solutions of the resulting integral equations are simple, which allows the determination of the kinematic properties of self-consistent models for these systems. These properties for then = 1 Toomre disk are presented in this study.

  4. Airborne Astronomy Symposium on the Galactic Ecosystem: From Gas to Stars to Dust, volume 73

    NASA Technical Reports Server (NTRS)

    Haas, Michael R. (Editor); Davidson, Jacqueline A. (Editor); Erickson, Edwin F. (Editor)

    1995-01-01

    This symposium was organized to review the science related to NASA's Airborne Astronomy Program on the occasion of the twentieth anniversary of the Kuiper Airborne Observatory (KAO). The theme selected, 'The Galactic Ecosystem: From Gas to Stars to Dust,' was considered to capture the underlying commonality of much of the research discussed. The 8 sessions were as follows: The Interstellar Medium; The Life Cycle of the ISM in Other Galaxies; Star and Planetary System Formation; Our Planetary System: The Solar System; The Enrichment of the Interstellar Medium; The Galactic Center: A Unique Region of the Galactic Ecosystem; Instrumentation for Airborne Astronomy; KAO History and Education; and Missions and the Future of Infrared Astronomy.

  5. Carbon Stars in the Galactic Halo

    NASA Astrophysics Data System (ADS)

    Totten, E. J.; Irwin, M. J.

    1996-04-01

    A byproduct of the APM high redshift quasar survey (Irwin et al. 1991) was the discovery of ~ 20 distant (20-100kpc) cool AGB carbon stars (all N-type) at high Galactic latitude. In August we used the INT+IDS to survey the rest of the high latitude SGC sky visible from La Palma and found 10 more similar carbon stars. Before this work there were only a handful of published faint high latitude cool carbon stars known (eg. Margon et al., 1984, Mould et al., 1985) and there has been speculation as to their origin (eg. Sanduleak, 1980, van den Bergh & Lafontaine, 1984). Intermediate age carbon stars (3 -- 7 Gyrs) seem unlikely to have formed in the halo in isolation from other star forming regions so how did they get there ? One possiblity that we are investigating, is that they arise from either the disruption of tidally captured dSph galaxies or are a manifestion of the long sought after optical component of the Magellanic Stream. Lack of proper motion rules out the possibility of them being dwarf carbon stars (eg. Warren et al., 1992); indeed no N-type carbon stars have been found to be dwarf carbon stars. Our optical spectroscopy confirms their carbon star type (they are indistinguishable from cool AGB carbon stars in nearby dwarf galaxies) and hence probable large distances. We are extending our survey to the NGC region, obtaining radial velocities and good S:N fluxed spectra for all the carbon stars. This will enable us to investigate their kinematics, true spatial distribution and hence their origin. Even, in the event that these objects are somehow an integral part of the Galactic halo, then their velocities and large distances will enable direct studies of the velocity ellipsoid and rotation of the outer halo (eg. Green et al., 1994).

  6. Disposal of high-level nuclear waste above the water table in arid regions

    USGS Publications Warehouse

    Roseboom, Eugene H.

    1983-01-01

    Locating a repository in the unsaturated zone of arid regions eliminates or simplifies many of the technological problems involved in designing a repository for operation below the water table and predicting its performance. It also offers possible accessibility and ease of monitoring throughout the operational period and possible retrieval of waste long after. The risks inherent in such a repository appear to be no greater than in one located in the saturated zone; in fact, many aspects of such a repository's performance will be much easier to predict and the uncertainties will be reduced correspondingly. A major new concern would be whether future climatic changes could produce significant consequences due to possible rise of the water table or increased flux of water through the repository. If spent fuel were used as a waste form, a second new concern would be the rates of escape of gaseous iodine-129 and carbon-14 to the atmosphere.

  7. Disposal of high-level nuclear waste above the water table in arid regions

    SciTech Connect

    Roseboom, E.H. Jr.

    1983-12-31

    Locating a repository in the unsaturated zone of arid regions eliminates or simplifies many of the technological problems involved in designing a repository for operation below the water table and predicting its performance. It also offers possible accessibility and ease of monitoring throughout the operational period and possible retrieval of waste long after. The risks inherent in such a repository appear to be no greater than in one located in the saturated zone; in fact, many aspects of such a repository`s performance will be much easier to predict and the uncertainties will be reduced correspondingly. A major new concern would be whether future climatic changes could produce significant consequences due to possible rise of the water table or increased flux of water through the repository. If spent fuel were used as a waste form, a second new concern would be the rates of escape of gaseous {sup 129}I and {sup 14}C to the atmosphere.

  8. Microscopic analysis of nuclear quantum phase transitions in the N{approx_equal}90 region

    SciTech Connect

    Li, Z. P.; Niksic, T.; Vretenar, D.; Meng, J.; Lalazissis, G. A.; Ring, P.

    2009-05-15

    The analysis of shape transitions in Nd isotopes, based on the framework of relativistic energy-density functionals and restricted to axially symmetric shapes in T. Niksic, D. Vretenar, G. A. Lalazissis, and P. Ring [Phys. Rev. Lett. 99, 092502 (2007)], is extended to the region Z=60,62,64 with N{approx_equal}90 and includes both {beta} and {gamma} deformations. Collective excitation spectra and transition probabilities are calculated starting from a five-dimensional Hamiltonian for quadrupole vibrational and rotational degrees of freedom, with parameters determined by constrained self-consistent relativistic mean-field calculations for triaxial shapes. The results reproduce available data and show that there is an abrupt change of structure at N=90 that can be approximately characterized by the X(5) analytic solution at the critical point of the first-order quantum phase transition between spherical and axially deformed shapes.

  9. Novel Yeast-based Strategy Unveils Antagonist Binding Regions on the Nuclear Xenobiotic Receptor PXR*

    PubMed Central

    Li, Hao; Redinbo, Matthew R.; Venkatesh, Madhukumar; Ekins, Sean; Chaudhry, Anik; Bloch, Nicolin; Negassa, Abdissa; Mukherjee, Paromita; Kalpana, Ganjam; Mani, Sridhar

    2013-01-01

    The pregnane X receptor (PXR) is a master regulator of xenobiotic metabolism, and its activity is critical toward understanding the pathophysiology of several diseases, including inflammation, cancer, and steatosis. Previous studies have demonstrated that ketoconazole binds to ligand-activated PXR and antagonizes receptor control of gene expression. Structure-function as well as computational docking analysis suggested a putative binding region containing critical charge clamp residues Gln-272, and Phe-264 on the AF-2 surface of PXR. To define the antagonist binding surface(s) of PXR, we developed a novel assay to identify key amino acid residues on PXR based on a yeast two-hybrid screen that examined mutant forms of PXR. This screen identified multiple “gain-of-function” mutants that were “resistant” to the PXR antagonist effects of ketoconazole. We then compared our screen results identifying key PXR residues to those predicted by computational methods. Of 15 potential or putative binding residues based on docking, we identified three residues in the yeast screen that were then systematically verified to functionally interact with ketoconazole using mammalian assays. Among the residues confirmed by our study was Ser-208, which is on the opposite side of the protein from the AF-2 region critical for receptor regulation. The identification of new locations for antagonist binding on the surface or buried in PXR indicates novel aspects to the mechanism of receptor antagonism. These results significantly expand our understanding of antagonist binding sites on the surface of PXR and suggest new avenues to regulate this receptor for clinical applications. PMID:23525103

  10. Constraints on galactic wind models

    NASA Astrophysics Data System (ADS)

    Meiksin, Avery

    2016-09-01

    Observational implications are derived for two standard models of supernovae-driven galactic winds: a freely expanding steady-state wind and a wind sourced by a self-similarly expanding superbubble including thermal heat conduction. It is shown that, for the steady-state wind, matching the measured correlation between the soft X-ray luminosity and star formation rate of starburst galaxies is equivalent to producing a scaled wind mass-loading factor relative to the star formation rate of 0.5-3, in agreement with the amount inferred from metal absorption line measurements. The match requires the asymptotic wind velocity v∞ to scale with the star formation rate dot{M}_{ast } (in M⊙ yr-1) approximately as v_∞ ≃ (700-1000) {{km s^{-1}}} {dot{M}_{ast }}^{1/6}. The implied mass injection rate is close to the amount naturally provided by thermal evaporation from the wall of a superbubble in a galactic disc, suggesting that thermal evaporation may be a major source of mass loading. The predicted mass-loading factors from thermal evaporation within the galactic disc alone, however, are somewhat smaller, 0.2-2, so that a further contribution from cloud ablation or evaporation within the wind may be required. Both models may account for the 1.4 GHz luminosity of unresolved radio sources within starburst galaxies for plausible parameters describing the distribution of relativistic electrons. Further observational tests to distinguish the models are suggested.

  11. The importance of warm, AGN-driven outflows in the nuclear regions of nearby ULIRGs

    NASA Astrophysics Data System (ADS)

    Rodríguez Zaurín, J.; Tadhunter, C. N.; Rose, M.; Holt, J.

    2013-06-01

    We present an optical spectroscopic study of a 90 per cent complete sample of nearby ULIRGs (z < 0.175) with optical Seyfert nuclei, with the aim of investigating the nature of the near-nuclear (r ≲ 3.5 kpc) warm gas outflows. A high proportion (94 per cent) of our sample show disturbed emission line kinematics in the form of broad (FWHM > 500 km s-1) and/or strongly blueshifted (ΔV < -150 km s-1) emission line components. This proportion is significantly higher than found in a comparison sample of nearby ultraluminous infrared galaxies (ULIRGs) that lack optical Seyfert nuclei (19 per cent). We also find evidence that the emission line kinematics of the Sy-ULIRGs are more highly disturbed than those of samples of non-ULIRG Seyferts and Palomar-Green quasars in the sense that, on average, their [O III] λλ5007, 4959 emission lines are broader and more asymmetric. The Sy-ULIRG sample encompasses a wide diversity of emission line profiles. In most individual objects, we are able to fit the profiles of all the emission lines of different ionization with a kinematic model derived from the strong [O III] λλ4959, 5007 lines, using between two and five Gaussian components. From these fits, we derive diagnostic line ratios that are used to investigate the ionization mechanisms for the different kinematic components. We show that, in general, the line ratios are consistent with gas of supersolar abundance photoionized by a combination of AGN and starburst activity, with an increasing contribution from the AGN with increasing FWHM of the individual kinematic components, and the AGN contribution dominating for the broadest components. However, shock ionization cannot be ruled out in some cases. Our derived upper limits on the mass outflows rates and kinetic powers of the emission line outflows show that they can be as energetically significant as the neutral and molecular outflows in ULIRGs - consistent with the requirements of the hydrodynamic simulations that include

  12. Galactic Centre hypershell model for the North Polar Spurs

    NASA Astrophysics Data System (ADS)

    Sofue, Y.; Habe, A.; Kataoka, J.; Totani, T.; Inoue, Y.; Nakashima, S.; Matsui, H.; Akita, M.

    2016-06-01

    The bipolar-hypershell (BHS) model for the North Polar Spurs (NPS-E, -W, and Loop I) and counter southern spurs (SPS-E and -W) is revisited based on numerical hydrodynamical simulations. Propagations of shock waves produced by energetic explosive events in the Galactic Centre are examined. Distributions of soft X-ray brightness on the sky at 0.25, 0.7, and 1.5 keV in the ±50° × ±50° region around the Galactic Centre are modelled by thermal emission from high-temperature plasma in the shock-compressed shell considering shadowing by the interstellar H I and H2 gases. The result is compared with the ROSAT wide field X-ray images in R2, 4, and 6 bands. The NPS and southern spurs are well reproduced by the simulation as shadowed dumbbell-shaped shock waves. We discuss the origin and energetics of the event in relation to the starburst and/or active galactic nucleus activities in the Galactic Centre.

  13. Survey of Water and Ammonia in the Galactic Center (SWAG)

    NASA Astrophysics Data System (ADS)

    Ott, Juergen; Jones, Paul; Staveley-Smith, Lister; Weiss, Axel; Henkel, Christian; Edwards, Philip; Burton, Michael; Menten, Karl; Schilke, Peter; Zhang, Qizhou; Longmore, Steven; Yusef-Zadeh, Farhad; Meier, David; Miller-Jones, James; Walsh, Andrew; Morris, Mark; Lang, Cornelia; Beuther, Henrik; Contreras, Yanett; Goldsmith, Paul; Crocker, Roland Murley; Corby, Joanna`; Anderson, Crystal; Ginsburg, Adam; Bally, John; Battersby, Cara; Mills, Elisabeth; Rosolowsky, Erik; Kruijssen, Diederik; Bihr, Simon; Morabito, Leah

    2014-04-01

    The Galactic Center contains 10% of all Galactic molecular gas (in the Central Molecular Zone; CMZ), material that is potentially converted into stars. The CMZ is an extreme environment. Many physical phenomena can be observed that shape the gas properties such as strong shocks, cosmic rays, high energy photons, turbulence, strong magnetic and tidal fields. We propose to perform the "Survey of Water and Ammonia in the Galactic Center (SWAG)'', a Large ATCA survey to cover the CMZ in the line-rich K-band to study the gas parameters that ultimately control the ability to cool, collapse and form stars. We ask to observe molecular species and continuum that will be used to (1) map the structure and kinematics of the gas at 1pc resolution; (2) obtain a large scale temperature map, accurate up to hundreds of K; (3) derive a map of opacity; (4) obtain an "archaeological" map of gas formation temperatures; (5) collate a water maser survey to trace actual star formation; (6) obtain maps of shock and photon-dominated region tracers; (7) derive maps of radio recombination lines to mark ionizing sources; (8) compute maps of continuum, spectral index and curvature; (9) derive a molecular clump catalog with properties for ~10000 objects. Together these data will allow us to disentangle the processes that control the state of the gas and capability to form stars. SWAG will serve as a benchmark for galactic nucleus physics at all cosmic epochs.

  14. Hi-GAL: The Herschel Infrared Galactic Plane Survey

    NASA Astrophysics Data System (ADS)

    Molinari, S.; Swinyard, B.; Bally, J.; Barlow, M.; Bernard, J.-P.; Martin, P.; Moore, T.; Noriega-Crespo, A.; Plume, R.; Testi, L.; Zavagno, A.; Abergel, A.; Ali, B.; André, P.; Baluteau, J.-P.; Benedettini, M.; Berné, O.; Billot, N. P.; Blommaert, J.; Bontemps, S.; Boulanger, F.; Brand, J.; Brunt, C.; Burton, M.; Campeggio, L.; Carey, S.; Caselli, P.; Cesaroni, R.; Cernicharo, J.; Chakrabarti, S.; Chrysostomou, A.; Codella, C.; Cohen, M.; Compiegne, M.; Davis, C. J.; de Bernardis, P.; de Gasperis, G.; Di Francesco, J.; di Giorgio, A. M.; Elia, D.; Faustini, F.; Fischera, J. F.; Fukui, Y.; Fuller, G. A.; Ganga, K.; Garcia-Lario, P.; Giard, M.; Giardino, G.; Glenn, J.:; Goldsmith, P.; Griffin, M.; Hoare, M.; Huang, M.; Jiang, B.; Joblin, C.; Joncas, G.; Juvela, M.; Kirk, J.; Lagache, G.; Li, J. Z.; Lim, T. L.; Lord, S. D.; Lucas, P. W.; Maiolo, B.; Marengo, M.; Marshall, D.; Masi, S.; Massi, F.; Matsuura, M.; Meny, C.; Minier, V.; Miville-Deschênes, M.-A.; Montier, L.; Motte, F.; Müller, T. G.; Natoli, P.; Neves, J.; Olmi, L.; Paladini, R.; Paradis, D.; Pestalozzi, M.; Pezzuto, S.; Piacentini, F.; Pomarès, M.; Popescu, C. C.; Reach, W. T.; Richer, J.; Ristorcelli, I.; Roy, A.; Royer, P.; Russeil, D.; Saraceno, P.; Sauvage, M.; Schilke, P.; Schneider-Bontemps, N.; Schuller, F.; Schultz, B.; Shepherd, D. S.; Sibthorpe, B.; Smith, H. A.; Smith, M. D.; Spinoglio, L.; Stamatellos, D.; Strafella, F.; Stringfellow, G.; Sturm, E.; Taylor, R.; Thompson, M. A.; Tuffs, R. J.; Umana, G.; Valenziano, L.; Vavrek, R.; Viti, S.; Waelkens, C.; Ward-Thompson, D.; White, G.; Wyrowski, F.; Yorke, H. W.; Zhang, Q.

    2010-03-01

    Hi-GAL, the Herschel infrared Galactic Plane Survey, is an Open Time Key Project of the Herschel Space Observatory. It will make an unbiased photometric survey of the inner Galactic plane by mapping a 2° wide strip in the longitude range midlmid < 60° in five wavebands between 70 μm and 500 μm. The aim of Hi-GAL is to detect the earliest phases of the formation of molecular clouds and high-mass stars and to use the optimum combination of Herschel wavelength coverage, sensitivity, mapping strategy, and speed to deliver a homogeneous census of star-forming regions and cold structures in the interstellar medium. The resulting representative samples will yield the variation of source temperature, luminosity, mass and age in a wide range of Galactic environments at all scales from massive YSOs in protoclusters to entire spiral arms, providing an evolutionary sequence for the formation of intermediate and high-mass stars. This information is essential to the formulation of a predictive global model of the role of environment and feedback in regulating the star-formation process. Such a model is vital to understanding star formation on galactic scales and in the early universe. Hi-GAL will also provide a science legacy for decades to come with incalculable potential for systematic and serendipitous science in a wide range of astronomical fields, enabling the optimum use of future major facilities such as JWST and ALMA.

  15. Nuclear Structure Studies in the 132Sn Region: Safe Coulex with Carbon Targets

    SciTech Connect

    Allmond, James M; Stuchbery, Andrew E; Galindo-Uribarri, Alfredo {nmn}; Padilla-Rodal, Elizabeth; Radford, David C; Batchelder, J. C.; Bingham, C. R.; Howard, Meredith E; Liang, J Felix; Manning, Brett M; Pain, Steven D; Stone, N. J.; Varner, Jr, Robert L; Yu, Chang-Hong

    2015-01-01

    The collective and single-particle structure of nuclei in the 132Sn region was recently studied by Coulomb excitation and heavy-ion induced transfer reactions using carbon, beryllium, and titanium targets. In particular, Coulomb excitation was used determine a complete set of electromagnetic moments for the first 2+ states and one-neutron transfer was used to probe the purity and evolution of single-neutron states. These recent experiments were conducted at the Holifield Radioactive Ion Beam Facility at ORNL using a CsI-HPGe detector array (BareBall- CLARION) to detect scattered particles and emitted gamma rays from the in-beam reactions. A Bragg-curve detector was used to measure the energy loss of the various beams through the targets and to measure the radioactive beam compositions. A sample of the Coulomb excitation results is presented here with an emphasis placed on 116Sn. In particular, the safe Coulex criterion for carbon targets will be analyzed and discussed.

  16. The molecular gas content of the nuclear region of M33

    NASA Astrophysics Data System (ADS)

    Wilson, Christine D.; Scoville, Nick

    1989-12-01

    The nearby Sc galaxy M33 has been mapped at half-beamwidth spacing out to a 3.5 arcmin radius in the CO J = 1-0 line using the NRAO 12 m telescope. The map reveals seven large-scale features with sizes of 200-400 pc, and in several cases they are associated with spiral arms. The masses of these structures are insufficient to gravitationally or tidally bind them given their measured sizes and velocity dispersions, and distances from the center of M33. The total mass of molecular hydrogen in the region mapped is 3.4 x 10 to the 7th solar, roughly twice the mass in atomic hydrogen. Within a radius of 800 pc, no evidence is seen for an exponential decrease in the azimuthally averaged molecular hydrogen column density. The rotation curve obtained from the molecular gas agrees well with previous observations, yielding a disk mass of 5 x 10 to the 8th solar, out to a radius of 800 pc and a molecular gas mass total mass ratio of 4 percent.

  17. ON THE SCATTER IN THE RADIUS-LUMINOSITY RELATIONSHIP FOR ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Kilerci Eser, E.; Vestergaard, M.; Peterson, B. M.; Denney, K. D.; Bentz, M. C. E-mail: vester@dark-cosmology.dk E-mail: peterson@astronomy.ohio-state.edu

    2015-03-01

    We investigate and quantify the observed scatter in the empirical relationship between the broad line region size R and the luminosity of the active galactic nucleus, in order to better understand its origin. This study is motivated by the indispensable role of this relationship in the mass estimation of cosmologically distant black holes, but may also be relevant to the recently proposed application of this relationship for measuring cosmic distances. We study six nearby reverberation-mapped active galactic nuclei (AGNs) for which simultaneous UV and optical monitoring data exist. We also examine the long-term optical luminosity variations of the Seyfert 1 galaxy NGC 5548 and employ Monte Carlo simulations to study the effects of the intrinsic variability of individual objects on the scatter in the global relationship for a sample of ∼40 AGNs. We find the scatter in this relationship has a correctable dependence on color. For individual AGNs, the size of the Hβ emitting region has a steeper dependence on the nuclear optical luminosity than on the UV luminosity, which can introduce a scatter of ∼0.08 dex into the global relationship, due the nonlinear relationship between the variations in the ionizing continuum and those in the optical continuum. Also, our analysis highlights the importance of understanding and minimizing the scatter in the relationship traced by the intrinsic variability of individual AGNs since it propagates directly into the global relationship. We find that using the UV luminosity as a substitute for the ionizing luminosity can reduce a sizable fraction of the current observed scatter of ∼0.13 dex.

  18. A Deep Submillimeter Survey of the Galactic Center

    NASA Astrophysics Data System (ADS)

    Pierce-Price, D.; Richer, J. S.; Greaves, J. S.; Holland, W. S.; Jenness, T.; Lasenby, A. N.; White, G. J.; Matthews, H. E.; Ward-Thompson, D.; Dent, W. R. F.; Zylka, R.; Mezger, P.; Hasegawa, T.; Oka, T.; Omont, A.; Gilmore, G.

    2000-12-01

    We present first results from a submillimeter continuum survey of the Galactic center ``central molecular zone'' (CMZ), made with the Submillimeter Common-User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope. SCUBA's scan-map mode has allowed us to make extremely wide field maps of thermal dust emission with unprecedented speed and sensitivity. We also discuss some issues related to the elimination of artifacts in scan-map data. Our simultaneous 850/450 μm maps have a total size of approximately 2.8d×0.5d (400×75 pc) elongated along the Galactic plane. They cover the Sagittarius A region, including Sgr A*, the circumnuclear disk, and the 20 and 50 km s-1 clouds; the area around the Pistol; Sgr B2, the brightest feature on the maps; and at their Galactic western and eastern edges the Sgr C and Sgr D regions. There are many striking features such as filaments and shell-like structures as well as point sources such as Sgr A* itself. The total mass in the CMZ is greater than that revealed in previous optically thin molecular line maps by a factor of ~3, and new details are revealed on scales down to 0.33 pc across this 400 pc-wide region.

  19. Nucleoporin's Like Charge Regions Are Major Regulators of FG Coverage and Dynamics Inside the Nuclear Pore Complex.

    PubMed

    Peyro, Mohaddeseh; Soheilypour, Mohammad; Ghavami, Ali; Mofrad, Mohammad R K

    2015-01-01

    Nucleocytoplasmic transport has been the subject of a large body of research in the past few decades. Recently, the focus of investigations in this field has shifted from studies of the overall function of the nuclear pore complex (NPC) to the examination of the role of different domains of phenylalanine-glycine nucleoporin (FG Nup) sequences on the NPC function. In our recent bioinformatics study, we showed that FG Nups have some evolutionarily conserved sequence-based features that might govern their physical behavior inside the NPC. We proposed the 'like charge regions' (LCRs), sequences of charged residues with only one type of charge, as one of the features that play a significant role in the formation of FG network inside the central channel. In this study, we further explore the role of LCRs in the distribution of FG Nups, using a recently developed coarse-grained molecular dynamics model. Our results demonstrate how LCRs affect the formation of two transport pathways. While some FG Nups locate their FG network at the center of the NPC forming a homogeneous meshwork of FG repeats, other FG Nups cover the space adjacent to the NPC wall. LCRs in the former group, i.e. FG Nups that form an FG domain at the center, tend to regulate the size of the highly dense, doughnut-shaped FG meshwork and leave a small low FG density area at the center of the pore for passive diffusion. On the other hand, LCRs in the latter group of FG Nups enable them to maximize their interactions and cover a larger space inside the NPC to increase its capability to transport numerous cargos at the same time. Finally, a new viewpoint is proposed that reconciles different models for the nuclear pore selective barrier function.

  20. Nucleoporin's Like Charge Regions Are Major Regulators of FG Coverage and Dynamics Inside the Nuclear Pore Complex.

    PubMed

    Peyro, Mohaddeseh; Soheilypour, Mohammad; Ghavami, Ali; Mofrad, Mohammad R K

    2015-01-01

    Nucleocytoplasmic transport has been the subject of a large body of research in the past few decades. Recently, the focus of investigations in this field has shifted from studies of the overall function of the nuclear pore complex (NPC) to the examination of the role of different domains of phenylalanine-glycine nucleoporin (FG Nup) sequences on the NPC function. In our recent bioinformatics study, we showed that FG Nups have some evolutionarily conserved sequence-based features that might govern their physical behavior inside the NPC. We proposed the 'like charge regions' (LCRs), sequences of charged residues with only one type of charge, as one of the features that play a significant role in the formation of FG network inside the central channel. In this study, we further explore the role of LCRs in the distribution of FG Nups, using a recently developed coarse-grained molecular dynamics model. Our results demonstrate how LCRs affect the formation of two transport pathways. While some FG Nups locate their FG network at the center of the NPC forming a homogeneous meshwork of FG repeats, other FG Nups cover the space adjacent to the NPC wall. LCRs in the former group, i.e. FG Nups that form an FG domain at the center, tend to regulate the size of the highly dense, doughnut-shaped FG meshwork and leave a small low FG density area at the center of the pore for passive diffusion. On the other hand, LCRs in the latter group of FG Nups enable them to maximize their interactions and cover a larger space inside the NPC to increase its capability to transport numerous cargos at the same time. Finally, a new viewpoint is proposed that reconciles different models for the nuclear pore selective barrier function. PMID:26658558

  1. A Galactic Fossil

    NASA Astrophysics Data System (ADS)

    2007-05-01

    star was then observed with UVES on the Very Large Telescope (VLT) for a total of 7.5 hours. A high quality spectrum was obtained that could never have been achieved without the combination of the large collecting power Kueyen, one of the individual 8.2-m Unit Telescopes of the VLT, and the extremely good sensitivity of UVES in the ultraviolet spectral region, where the lines from the elements are observed. For the first time, the age dating involved both radioactive elements in combination with the three other neutron-capture elements europium, osmium, and iridium. "Until now, it has not been possible to measure more than a single cosmic clock for a star. Now, however, we have managed to make six measurements in this one star", says Frebel. Ever since the star was born, these "clocks" have ticked away over the eons, unaffected by the turbulent history of the Milky Way. They now read 13.2 billion years. The Universe being 13.7 billion years old, this star clearly formed very early in the life of our own Galaxy, which must also formed very soon after the Big Bang. More Information This research is reported in a paper published in the 10 May issue of the Astrophysical Journal ("Discovery of HE 1523-0901, a Strongly r-Process Enhanced Metal-Poor Star with Detected Uranium", by A. Frebel et al.). The team includes Anna Frebel (McDonald Observatory, Texas) and John E. Norris (The Australian National University), Norbert Christlieb (Uppsala University, Sweden, and Hamburg Observatory, Germany), Christopher Thom (University of Chicago, USA, and Swinburne University of Technlogy, Australia), Timothy C. Beers (Michigan State University, USA), Jaehyon Rhee (Center for Space Astrophysics, Yonsei University, Korea, and Caltech, USA).

  2. Particle Acceleration in Active Galactic Nuclei

    NASA Technical Reports Server (NTRS)

    Miller, James A.

    1997-01-01

    The high efficiency of energy generation inferred from radio observations of quasars and X-ray observations of Seyfert active galactic nuclei (AGNs) is apparently achieved only by the gravitational conversion of the rest mass energy of accreting matter onto supermassive black holes. Evidence for the acceleration of particles to high energies by a central engine is also inferred from observations of apparent superluminal motion in flat spectrum, core-dominated radio sources. This phenomenon is widely attributed to the ejection of relativistic bulk plasma from the nuclei of active galaxies, and accounts for the existence of large scale radio jets and lobes at large distances from the central regions of radio galaxies. Reports of radio jets and superluminal motion from galactic black hole candidate X-ray sources indicate that similar processes are operating in these sources. Observations of luminous, rapidly variable high-energy radiation from active galactic nuclei (AGNs) with the Compton Gamma Ray Observatory show directly that particles are accelerated to high energies in a compact environment. The mechanisms which transform the gravitational potential energy of the infalling matter into nonthermal particle energy in galactic black hole candidates and AGNs are not conclusively identified, although several have been proposed. These include direct acceleration by static electric fields (resulting from, for example, magnetic reconnection), shock acceleration, and energy extraction from the rotational energy of Kerr black holes. The dominant acceleration mechanism(s) operating in the black hole environment can only be determined, of course, by a comparison of model predictions with observations. The purpose of the work proposed for this grant was to investigate stochastic particle acceleration through resonant interactions with plasma waves that populate the magnetosphere surrounding an accreting black hole. Stochastic acceleration has been successfully applied to the

  3. Origin of the hard x-ray emission from the Galactic plane.

    PubMed

    Ebisawa, K; Maeda, Y; Kaneda, H; Yamauchi, S

    2001-08-31

    The Galactic plane is a strong emitter of hard x-rays (2 to 10 kiloelectron volts), and the emission forms a narrow continuous ridge. The currently known hard x-ray sources are far too few to explain the ridge x-ray emission, and the fundamental question of whether the ridge emission is ultimately resolved into numerous dimmer discrete sources or truly diffuse emission has not yet been settled. In order to obtain a decisive answer, using the Chandra X-ray Observatory, we carried out the deepest hard x-ray survey of a Galactic plane region that is devoid of known x-ray point sources. We detected at least 36 new hard x-ray point sources in addition to strong diffuse emission within a 17' by 17' field of view. The surface density of the point sources is comparable to that at high Galactic latitudes after the effects of Galactic absorption are considered. Therefore, most of these point sources are probably extragalactic, presumably active galaxies seen through the Galactic disk. The Galactic ridge hard x-ray emission is diffuse, which indicates omnipresence within the Galactic plane of a hot plasma, the energy density of which is more than one order of magnitude higher than any other substance in the interstellar space. PMID:11498545

  4. X-Ray Constraints on Accretion and Starburst Processes in Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Ptak, Andrew Francis

    The results of X-ray observations of a sample of nearby low-luminosity active galactic nuclei (LLAGN), low-ionization nuclear emission line regions (LINERs), and starburst galaxies are presented. In general the 0.4-10.0 keV spectra of this heterogenous sample are fit well by a two-component model consisting of an optically-thin plasma with a temperature of ~0.7 keV and a power-law model with a photon index of ~1.7. Both the hot gas component and the hard, possibly nonthermal, X-ray emission appear to be common features of galaxies showing signs of nuclear activity. The spectrum of the hard component (roughly in the 2-10 keV bandpass) is most consistent with AGN, which are postulated to be accreting supermassive blackholes. X-ray binaries that are probably accreting blackhole candidates also appear to contribute significantly to the hard, and possibly to a lesser extent, the soft X-ray emission. Very hot (T~108 K) gas in a 'superwind' may also be contributing to the hard flux in some cases, probably concentrated in the nuclear regions of the galaxies. Another possible contributor to the featureless X-ray continuum may be inverse-Compton scattering of infrared photons, but the contribution of this component is sensitive to model assumptions. The soft emission appears to be supernovae-heated interstellar medium (ISM). In some cases, the SN-heating is actually in the form of a superwind, in which case ~90% of the X-ray emitting gas is 'swept-up' ISM and the remainder is (cooling) superwind emission out in the disks of the galaxies. Very low absolutes abundances are observed, but the uncertainties are large. Relative abundances are more secure and suggest that Fe is underabundant relative to α-process elements. The low relative Fe abundance may be due to enrichment by Type-II supernovae and∨ dust depletion, but non-equilibrium ionization may also be playing a part. Future observations by X-ray telescopes with high spatial and spectral resolution and improved

  5. Galactic H2O maser surveys

    NASA Astrophysics Data System (ADS)

    Felli, Marcello; Palagi, Francesco

    The first part is devoted to give an updated situation of the single dish surveys of galactic H2O masers, with particular emphasis on those associated with star forming regions (SFR). The main input for this comes from the updated Arcetri Atlas of H2O masers obtained with the Medicina 32m radio telescope. Available information on variability of the maser emission is also briefly reviewed. The second part gives a description of the results derived from the comparison of VLA observations of H2O masers in SFR and near IR images. J, H, K images are able to reveal the stellar cluster present in these highly obscured regions. IT is found that a stellar source with strong H-K excess is almost always associated with the maser spots (and not necessarily with an ultracompact HII region) and represents the direct evidence of the Young Stellar Object (YSO) which is required for the maser pumping. There are several indications suggesting that the H2O maser/near IR source may represent one of the earliest manifestation of a recently formed star. Finally, the importance of a coordination between near IR full sky surveys and H2O maser surveys is briefly discussed.

  6. HERSCHEL OBSERVATIONS REVEAL ANOMALOUS MOLECULAR ABUNDANCES TOWARD THE GALACTIC CENTER

    SciTech Connect

    Sonnentrucker, P.; Neufeld, D. A.; Indriolo, N.; Gerin, M.; De Luca, M.; Lis, D. C.; Goicoechea, J. R.

    2013-01-20

    We report the Herschel detections of hydrogen fluoride (HF) and para-water (p-H{sub 2}O) in gas intercepting the sight lines to two well-studied molecular clouds in the vicinity of the Sgr A complex: G-0.02-0.07 (the {sup +}50 km s{sup -1} cloud{sup )} and G-0.13-0.08 (the {sup +}20 km s{sup -1} cloud{sup )}. Toward both sight lines, HF and water absorption components are detected over a wide range of velocities covering {approx}250 km s{sup -1}. For all velocity components with V{sub LSR} > -85 km s{sup -1}, we find that the HF and water abundances are consistent with those measured toward other sight lines probing the Galactic disk gas. The velocity components with V{sub LSR} {<=} -85 km s{sup -1}, which are known to trace gas residing within {approx}200 pc of the Galactic center, however, exhibit water vapor abundances with respect to HF at least a factor three higher than those found in the Galactic disk gas. Comparison with CH data indicates that our observations are consistent with a picture where HF and a fraction of the H{sub 2}O absorption arise in diffuse molecular clouds showing Galactic disk-like abundances while the bulk of the water absorption arises in warmer (T {>=} 400 K) diffuse molecular gas for V{sub LSR} {<=} -85 km s{sup -1}. This diffuse Interstellar Medium (ISM) phase has also been recently revealed through observations of CO, HF, H{sup +}{sub 3}, and H{sub 3}O{sup +} absorption toward other sight lines probing the Galactic center inner region.

  7. Widespread rotationally hot hydronium ion in the galactic interstellar medium

    SciTech Connect

    Lis, D. C.; Phillips, T. G.; Schilke, P.; Comito, C.; Higgins, R. E-mail: tgp@submm.caltech.edu E-mail: ccomito@ph1.uni-koeln.de; and others

    2014-04-20

    We present new Herschel observations of the (6,6) and (9,9) inversion transitions of the hydronium ion toward Sagittarius B2(N) and W31C. Sensitive observations toward Sagittarius B2(N) show that the high, ∼500 K, rotational temperatures characterizing the population of the highly excited metastable H{sub 3}O{sup +} rotational levels are present over a wide range of velocities corresponding to the Sagittarius B2 envelope, as well as the foreground gas clouds between the Sun and the source. Observations of the same lines toward W31C, a line of sight that does not intersect the Central Molecular Zone but instead traces quiescent gas in the Galactic disk, also imply a high rotational temperature of ∼380 K, well in excess of the kinetic temperature of the diffuse Galactic interstellar medium. While it is plausible that some fraction of the molecular gas may be heated to such high temperatures in the active environment of the Galactic center, characterized by high X-ray and cosmic-ray fluxes, shocks, and high degree of turbulence, this is unlikely in the largely quiescent environment of the Galactic disk clouds. We suggest instead that the highly excited states of the hydronium ion are populated mainly by exoergic chemical formation processes and the temperature describing the rotational level population does not represent the physical temperature of the medium. The same arguments may be applicable to other symmetric top rotors, such as ammonia. This offers a simple explanation of the long-standing puzzle of the presence of a pervasive, hot molecular gas component in the central region of the Milky Way. Moreover, our observations suggest that this is a universal process not limited to the active environments associated with galactic nuclei.

  8. Stellar Abundances of the Galactic Thick Disk

    NASA Astrophysics Data System (ADS)

    Pettinger, M. M.; Bernkopf, J.; Fuhrmann, K.; Korn, A. J.; Gehren, T.

    We present the results from model atmosphere analyses of two G dwarfs of the Galactic thick disk, 72 Her and HD 64606. High resolution, high signal-to-noise échelle spectra were obtained with the FOCES spectrograph on the 2.2m telescope of the Calar Alto observatory, Spain. Due to the well-defined blaze function of FOCES the determination of the continuum within an order and from order to order in the Hα, Hβ (for Teff) and Mg Ib triplett (for log g) region is very precise and leads to very accurately determined spectroscopic stellar parameters. The aim of our analysis is to study the chemical behaviour of the thick disk in particular with respect to the α-, r- and s-process elements. The principal results are as follows: both stars show significant enhancement in all analysed α-elements, in the r-process element Eu as well as in Al and Zn. Mn and the s-process element Ba are underabundant relative to iron while the other iron-peak elements exhibit a slight enhancement. N, Na, Ce and the r-process element Sr also show a weak overabundance. Based on the very accurate HIPPARCOS astrometry the stellar ages were determined to be 13 Gyrs. This allows us to identify both stars as members of the thick disk which is also in accord with their kinematics. The high Eu/Ba ratios are consistent with the ratio expected for stars older than 12 Gyr under the assumption of r-process dominated enrichment in the early phase of Galactic chemical evolution. We argue that the high [Al/Fe] and [Zn/Fe] ratios potentially allow to spectroscopically distinguish between the halo and thick-disk populations.

  9. HEGRA Observations of Galactic Sources

    NASA Astrophysics Data System (ADS)

    Völk, H.; Hegea Collaboration

    2000-06-01

    In this talk I will first give a summary of the observations of expected Galactic TeV gamma-ray sources with the HEGRA CT-Sytem since the Kruger Park Workshop in 1997. Then I will go into some detail regarding the observations of Supernova Remnants (SNRs), especially those of Tycho's SNR and of Cas A. The emphasis will not be on all aspects of these published data. I will rather review the selection of these observational targets, and discuss some of the physical implications of the results.

  10. HEGRA observations of Galactic sources

    NASA Astrophysics Data System (ADS)

    HEGRA Collaboration

    2000-06-01

    In this talk I will first give a summary of the observations of expected Galactic TeV γ-ray sources with the HEGRA CT-System since the Kruger Park Workshop in 1997. Then I will go into some detail regarding the observations of Supernova Remnants (SNRs), especially those of Tycho's SNR and of Cas A. The emphasis will not be on all aspects of these published data. I will rather review the selection of these observational targets, and discuss some of the physical implications of the results. .

  11. Kohn-Sham kinetic energy density in the nuclear and asymptotic regions: Deviations from the von Weizsäcker behavior and applications to density functionals

    NASA Astrophysics Data System (ADS)

    Della Sala, Fabio; Fabiano, Eduardo; Constantin, Lucian A.

    2015-01-01

    We show that the Kohn-Sham positive-definite kinetic energy (KE) density significantly differs from the von Weizsäcker (VW) one at the nuclear cusp as well as in the asymptotic region. At the nuclear cusp, the VW functional is shown to be linear, and the contribution of p -type orbitals to the KE density is theoretically derived and numerically demonstrated in the limit of infinite nuclear charge as well in the semiclassical limit of neutral large atoms. In the latter case, it reaches 12% of the KE density. In the asymptotic region we find new exact constraints for meta-generalized gradient approximation (meta-GGA) exchange functionals: with an exchange enhancement factor proportional to √{α }, where α is the common meta-GGA ingredient, both the exchange energy density and the potential are proportional to the exact ones. In addition, this describes exactly the large-gradient limit of quasi-two-dimensional systems.

  12. Dielectronic Recombination In Active Galactic Nuclei

    NASA Technical Reports Server (NTRS)

    Lukic, D. V.; Schnell, M.; Savin, D. W.; Altun, Z.; Badnell, N.; Brandau, C.; Schmidt, E. W.; Mueller, A.; Schippers, S.; Sprenger, F.; Lestinsky, M.; Wolf, A.

    2006-01-01

    XMM-Newton and Chandra observations of active galactic nuclei (AGN) show rich spectra of X-ray absorption lines. These observations have detected a broad unresolved transition array (UTA) between approx. 15-17 A. This is attributed to inner-shell photoexcitation of M-shell iron ions. Modeling these UTA features is currently limited by uncertainties in the low-temperature dielectronic recombination (DR) data for M-shell iron. In order to resolve this issue, and to provide reliable iron M-shell DR data for plasma modeling, we are carrying out a series of laboratory measurements using the heavy-ion Test Storage Ring (TSR) at the Max-Plank-Institute for Nuclear Physics in Heidelberg, Germany. Currently, laboratory measurements of low temperature DR can only be performed at storage rings. We use the DR data obtained at TSR, to calculate rate coefficients for plasma modeling and to benchmark theoretical DR calculations. Here we report our recent experimental results for DR of Fe XIV forming Fe XIII.

  13. The central parsecs of active galactic nuclei: challenges to the torus

    NASA Astrophysics Data System (ADS)

    Prieto, M. A.; Mezcua, M.; Fernández-Ontiveros, J. A.; Schartmann, M.

    2014-08-01

    Type 2 active galactic nuclei (AGN) are by definition nuclei in which the broad-line region and continuum light are hidden at optical/UV wavelengths by dust. Via accurate registration of infrared (IR) Very Large Telescope adaptive optics images with optical Hubble Space Telescope images we unambiguously identify the precise location of the nucleus of a sample of nearby, type 2 AGN. Dust extinction maps of the central few kpc of these galaxies are constructed from optical-IR colour images, which allow tracing the dust morphology at scales of few pc. In almost all cases, the IR nucleus is shifted by several tens of pc from the optical peak and its location is behind a dust filament, prompting to this being a major, if not the only, cause of the nucleus obscuration. These nuclear dust lanes have extinctions AV ≥ 3 - 6 mag, sufficient to at least hide the low-luminosity AGN class, and in some cases are observed to connect with kpc-scale dust structures, suggesting that these are the nuclear fueling channels. A precise location of the ionized gas Hα and [Si VII] 2.48 μ coronal emission lines relative to those of the IR nucleus and dust is determined. The Hα peak emission is often shifted from the nucleus location and its sometimes conical morphology appears not to be caused by a nuclear - torus - collimation but to be strictly defined by the morphology of the nuclear dust lanes. Conversely, [Si VII] 2.48 μ emission, less subjected to dust extinction, reflects the truly, rather isotropic, distribution of the ionized gas. All together, the precise location of the dust, ionized gas and nucleus is found compelling enough to cast doubts on the universality of the pc-scale torus and supports its vanishing in low-luminosity AGN. Finally, we provide the most accurate position of the NGC 1068 nucleus, located at the south vertex of cloud B.

  14. A MILLIMETER-WAVE GALACTIC PLANE SURVEY WITH THE BICEP POLARIMETER

    SciTech Connect

    Bierman, E. M.; Keating, B. G.; Barron, D.; Kaufman, J. P.; Matsumura, T.; Dowell, C. D.; Bock, J. J.; Chiang, H. C.; Culverhouse, T. L.; Hristov, V. V.; Kovac, J. M.; Lange, A. E.; Ade, P.; Barkats, D.; Battle, J. O.; Leitch, E. M.; Duband, L.; Hivon, E. F.; Holzapfel, W. L.; Kuo, C. L.

    2011-11-10

    In order to study inflationary cosmology and the Milky Way Galaxy's composition and magnetic field structure, Stokes I, Q, and U maps of the Galactic plane covering the Galactic longitude range 260 Degree-Sign < l < 340 Degree-Sign in three atmospheric transmission windows centered on 100, 150, and 220 GHz are presented. The maps sample an optical depth 1 {approx}< A{sub V} {approx}< 30, and are consistent with previous characterizations of the Galactic millimeter-wave frequency spectrum and the large-scale magnetic field structure permeating the interstellar medium. The polarization angles in all three bands are generally perpendicular to those measured by starlight polarimetry as expected and show changes in the structure of the Galactic magnetic field on the scale of 60 Degree-Sign . The frequency spectrum of degree-scale Galactic emission is plotted between 23 and 220 GHz (including WMAP data) and is fit to a two-component (synchrotron and dust) model showing that the higher frequency BICEP data are necessary to tightly constrain the amplitude and spectral index of Galactic dust. Polarized emission is detected over the entire region within two degrees of the Galactic plane, indicating the large-scale magnetic field is oriented parallel to the plane of the Galaxy. A trend of decreasing polarization fraction with increasing total intensity is observed, ruling out the simplest model of a constant Galactic magnetic field orientation along the line of sight in the Galactic plane. A generally increasing trend of polarization fraction with electromagnetic frequency is found, varying from 0.5%-1.5% at frequencies below 50 GHz to 2.5%-3.5% above 90 GHz. The effort to extend the capabilities of BICEP by installing 220 GHz band hardware is described along with analysis of the new band.

  15. Galactic Building Blocks Seen Swarming Around Andromeda

    NASA Astrophysics Data System (ADS)

    2004-02-01

    Green Bank, WV - A team of astronomers using the National Science Foundation's Robert C. Byrd Green Bank Telescope (GBT) has made the first conclusive detection of what appear to be the leftover building blocks of galaxy formation -- neutral hydrogen clouds -- swarming around the Andromeda Galaxy, the nearest large spiral galaxy to the Milky Way. This discovery may help scientists understand the structure and evolution of the Milky Way and all spiral galaxies. It also may help explain why certain young stars in mature galaxies are surprisingly bereft of the heavy elements that their contemporaries contain. Andromeda Galaxy This image depicts several long-sought galactic "building blocks" in orbit of the Andromeda Galaxy (M31). The newfound hydrogen clouds are depicted in a shade of orange (GBT), while gas that comprises the massive hydrogen disk of Andromeda is shown at high-resolution in blue (Westerbork Sythesis Radio Telescope). CREDIT: NRAO/AUI/NSF, WSRT (Click on Image for Larger Version) "Giant galaxies, like Andromeda and our own Milky Way, are thought to form through repeated mergers with smaller galaxies and through the accretion of vast numbers of even lower mass 'clouds' -- dark objects that lack stars and even are too small to call galaxies," said David A. Thilker of the Johns Hopkins University in Baltimore, Maryland. "Theoretical studies predict that this process of galactic growth continues today, but astronomers have been unable to detect the expected low mass 'building blocks' falling into nearby galaxies, until now." Thilker's research is published in the Astrophysical Journal Letters. Other contributors include: Robert Braun of the Netherlands Foundation for Research in Astronomy; Rene A.M. Walterbos of New Mexico State University; Edvige Corbelli of the Osservatorio Astrofisico di Arcetri in Italy; Felix J. Lockman and Ronald Maddalena of the National Radio Astronomy Observatory (NRAO) in Green Bank, West Virginia; and Edward Murphy of the

  16. Identification of a nuclear matrix attachment region like sequence in the last intron of PI3K{gamma}

    SciTech Connect

    Dai Bingbing; Ying Lei; Cai Rong; Li Ying; Zhang Xingqian; Lu Jian; Qian Guanxiang . E-mail: sundai0@163.com

    2006-03-10

    MARs are not only the structure bases of chromatin higher order structure but also have much biological significance. In this study, the whole sequence of about 100 kb in length from BAC clone of GS1-223D4 (GI: 5931478), in which human PI3K{gamma} gene is localized, was analyzed by two online-based computer programs, MARFinder and SMARTest. A strong potential MAR was predicted in the last and largest intron of PI3K{gamma}. The predicted 2 kb MAR, we refer to PIMAR, was further analyzed through biochemical methods in vitro and in vivo. The results showed that the PIMAR could be associated with nuclear matrices from HeLa cells both in vitro and in vivo. Further reporter gene analysis showed that in the transient transfection the expression of reporter gene linked with reversed PIMAR was repressed slightly, while in stably integrated state, the luciferase reporter both linked with reversed and orientated PIMAR was enhanced greatly in NIH-3T3 and K-562. These results suggest that the PIMAR maybe has the capacity of shielding integrated heterogeneous gene from chromatin position effect. Through combination of computer program analysis with confirmation by biochemical methods, we identified, for First time, a 2 kb matrix attachment region like sequence in the last intron of human PI3K{gamma}.

  17. [Sequence of the ITS region of nuclear ribosomal DNA(nrDNA) in Xinjiang wild Dianthus and its phylogenetic relationship].

    PubMed

    Zhang, Lu; Cai, You-Ming; Zhuge, Qiang; Zou, Hui-Yu; Huang, Min-Ren

    2002-06-01

    Xinjiang is a center of distribution and differentiation of genus Dianthus in China, and has a great deal of species resources. The sequences of ITS region (including ITS-1, 5.8S rDNA and ITS-2) of nuclear ribosomal DNA from 8 species of genus Dianthus wildly distributed in Xinjiang were determined by direct sequencing of PCR products. The result showed that the size of the ITS of Dianthus is from 617 to 621 bp, and the length variation is only 4 bp. There are very high homogeneous (97.6%-99.8%) sequences between species, and about 80% homogeneous sequences between genus Dianthus and outgroup. The sequences of ITS in genus Dianthus are relatively conservative. In general, there are more conversion than transition in the variation sites among genus Dianthus. The conversion rates are relatively high, and the ratios of conversion/transition are 1.0-3.0. On the basis of phylogenetic analysis of nucleotide sequences the species of Dianthus in China would be divided into three sections. There is a distant relationship between sect. Barbulatum Williams and sect. Dianthus and between sect. Barbulatum Williams and sect. Fimbriatum Williams, and there is a close relationship between sect. Dianthus and sect. Fimbriatum Williams. From the phylogenetic tree of ITS it was found that the origin of sect. Dianthusis is earlier than that of sect. Fimbriatum Williams and sect. Barbulatum Williams.

  18. Inferring Invasion History of Red Swamp Crayfish (Procambarus clarkii) in China from Mitochondrial Control Region and Nuclear Intron Sequences

    PubMed Central

    Li, Yanhe; Guo, Xianwu; Chen, Liping; Bai, Xiaohui; Wei, Xinlan; Zhou, Xiaoyun; Huang, Songqian; Wang, Weimin

    2015-01-01

    Identifying the dispersal pathways of an invasive species is useful for adopting the appropriate strategies to prevent and control its spread. However, these processes are exceedingly complex. So, it is necessary to apply new technology and collect representative samples for analysis. This study used Approximate Bayesian Computation (ABC) in combination with traditional genetic tools to examine extensive sample data and historical records to infer the invasion history of the red swamp crayfish, Procambarus clarkii, in China. The sequences of the mitochondrial control region and the proPOx intron in the nuclear genome of samples from 37 sites (35 in China and one each in Japan and the USA) were analyzed. The results of combined scenarios testing and historical records revealed a much more complex invasion history in China than previously believed. P. clarkii was most likely originally introduced into China from Japan from an unsampled source, and the species then expanded its range primarily into the middle and lower reaches and, to a lesser extent, into the upper reaches of the Changjiang River in China. No transfer was observed from the upper reaches to the middle and lower reaches of the Changjiang River. Human-mediated jump dispersal was an important dispersal pathway for P. clarkii. The results provide a better understanding of the evolutionary scenarios involved in the rapid invasion of P. clarkii in China. PMID:26132567

  19. Effect of indoor air pollution from biomass fuel use on argyrophilic nuclear organizer regions in buccal epithelial cells.

    PubMed

    Mondal, Nandan K; Dutta, Anindita; Banerjee, Anirban; Chakraborty, Sreeparna; Lahiri, Twisha; Ray, Manas Ranjan

    2009-01-01

    This study investigated the effect of indoor air pollution from biomass-fuel use on the expression of argyrophilic nucleolar organizer regions (AgNORs), an indicator of ribosome biosynthesis, in epithelial cells of oral mucosa. AgNORs were evaluated using cytochemical staining in 62 nonsmoking indian women (median age, 34 years), who cooked exclusively with biomass, and 55 age-matched women, who were from a similar neighborhood and cooked with relatively clean liquefied petroleum gas (LPG). Concentrations of particulate pollutants in indoor air were measured using a real-time aerosol monitor. Compared to the LPG-using controls, biomass-fuel users showed a remarkably increased number of AgNOR dots per nucleus (6.08 +/-2.26 vs 3.16 +/-0.86, p < 0.001), AgNOR size (0.85 +/-0.19 vs 0.53 +/-0.15 mum2, p < 0.001), and percentage of AgNOR-occupied nuclear area (4.88 +/-1.49 vs 1.75 +/-0.13%, p < 0.001). Biomass-using households had 2 to 4 times more particulate pollutants than that of LPG-using households. The changes in AgNOR expression were positively associated with PM10 and PM2.5 levels in indoor air after controlling for potential confounders such as age, kitchen location, and family income. Thus, biomass smoke appears to be a risk factor for abnormal cell growth via upregulation of ribosome biogenesis.

  20. Galactic cold cores. V. Dust opacity

    NASA Astrophysics Data System (ADS)

    Juvela, M.; Ristorcelli, I.; Marshall, D. J.; Montillaud, J.; Pelkonen, V.-M.; Ysard, N.; McGehee, P.; Paladini, R.; Pagani, L.; Malinen, J.; Rivera-Ingraham, A.; Lefèvre, C.; Tóth, L. V.; Montier, L. A.; Bernard, J.-P.; Martin, P.

    2015-12-01

    Context. The project Galactic Cold Cores has carried out Herschel photometric observations of interstellar clouds where the Planck satellite survey has located cold and compact clumps. The sources represent different stages of cloud evolution from starless clumps to protostellar cores and are located in different Galactic environments. Aims: We examine this sample of 116 Herschel fields to estimate the submillimetre dust opacity and to search for variations that might be attributed to the evolutionary stage of the sources or to environmental factors, including the location within the Galaxy. Methods: The submillimetre dust opacity was derived from Herschel data, and near-infrared observations of the reddening of background stars are converted into near-infrared optical depth. We investigated the systematic errors affecting these parameters and used modelling to correct for the expected biases. The ratio of 250 μm and J band opacities is correlated with the Galactic location and the star formation activity. We searched for local variations in the ratio τ(250 μm)/τ(J) using the correlation plots and opacity ratio maps. Results: We find a median ratio of τ(250 μm) /τ(J) = (1.6 ± 0.2) × 10-3, which is more than three times the mean value reported for the diffuse medium. Assuming an opacity spectral index β = 1.8 instead of β = 2.0, the value would be lower by ~ 30%. No significant systematic variation is detected with Galactocentric distance or with Galactic height. Examination of the τ(250 μm) /τ(J) maps reveals six fields with clear indications of a local increase of submillimetre opacity of up to τ(250 μm) /τ(J) ~ 4 × 10-3 towards the densest clumps. These are all nearby fields with spatially resolved clumps of high column density. Conclusions: We interpret the increase in the far-infrared opacity as a sign of grain growth in the densest and coldest regions of interstellar clouds. Planck (http://www.esa.int/Planck) is a project of the European

  1. Introduction to Galactic Chemical Evolution

    NASA Astrophysics Data System (ADS)

    Matteucci, Francesca

    2016-04-01

    In this lecture I will introduce the concept of galactic chemical evolution, namely the study of how and where the chemical elements formed and how they were distributed in the stars and gas in galaxies. The main ingredients to build models of galactic chemical evolution will be described. They include: initial conditions, star formation history, stellar nucleosynthesis and gas flows in and out of galaxies. Then some simple analytical models and their solutions will be discussed together with the main criticisms associated to them. The yield per stellar generation will be defined and the hypothesis of instantaneous recycling approximation will be critically discussed. Detailed numerical models of chemical evolution of galaxies of different morphological type, able to follow the time evolution of the abundances of single elements, will be discussed and their predictions will be compared to observational data. The comparisons will include stellar abundances as well as interstellar medium ones, measured in galaxies. I will show how, from these comparisons, one can derive important constraints on stellar nucleosynthesis and galaxy formation mechanisms. Most of the concepts described in this lecture can be found in the monograph by Matteucci (2012).

  2. Special Features of Galactic Dynamics

    NASA Astrophysics Data System (ADS)

    Efthymiopoulos, Christos; Voglis, Nikos; Kalapotharakos, Constantinos

    This is an introductory article to some basic notions and currently open problems of galactic dynamics. The focus is on topics mostly relevant to the so-called `new methods' of celestial mechanics or Hamiltonian dynamics, as applied to the ellipsoidal components of galaxies, i.e., to the elliptical galaxies and to the dark halos and bulges of disk galaxies. Traditional topics such as Jeans theorem, the role of a `third integral' of motion, Nekhoroshev theory, violent relaxation, and the statistical mechanics of collisionless stellar systems are first discussed. The emphasis is on modern extrapolations of these old topics. Recent results from orbital and global dynamical studies of galaxies are then shortly reviewed. The role of various families of orbits in supporting self-consistency, as well as the role of chaos in galaxies, are stressed. A description is then given of the main numerical techniques of integration of the N-body problem in the framework of stellar dynamics and of the results obtained via N-Body experiments. A final topic is the secular evolution and self-organization of galactic systems.

  3. Revelations in our own backyard: Chandra’s unique Galactic Center discoveries

    PubMed Central

    Markoff, Sera

    2010-01-01

    Before the launch of Chandra, our Galactic Center supermassive black hole, Sgr A*, had never been positively identified outside the radio bands. A great deal has changed in the past decade, starting with the discovery that our own backyard harbors a very weak, yet clearly active, galactic nucleus. I will review how this revelation has been a boon for accretion studies around black holes in general and has helped us place our own Galaxy in context within the active galactic nuclei (AGN) zoology. Chandra’s exquisite resolution has also unveiled entirely new populations of faint sources and transients, as well as regions of extreme gas dynamics and hints of prior, more typical AGN-like activity in our Galactic Center. PMID:20368467

  4. High-velocity OH/IR stars at the Galactic centre

    NASA Astrophysics Data System (ADS)

    van Langevelde, H. J.; Brown, A. G. A.; Lindqvist, M.; Habing, H. J.; de Zeeuw, P. T.

    1992-07-01

    We present the results of a small survey for OH/IR stars at high radial velocities in the Galactic center region performed with the VLA and the Nancay telescope. We have detected two new OH/IR stars, one at a peculiar velocity of -309 km/s, the other at -355 km/s. These two objects and one previously detected high-velocity OH/IR star (OH 0.3-0.2, Baud et al., 1975) stand out in the 1, v diagram of OH/IR stars at the Galactic center. Are these stars just on the extreme edge of the radial velocity distribution? Or are these objects no longer bound to the Galactic center? We discuss these possibilities, showing that these are most likely bulge stars on elongated orbits passing close to the Galactic center.

  5. A deep look at the nuclear region of UGC 5101 through high angular resolution mid-IR data with GTC/CanariCam

    NASA Astrophysics Data System (ADS)

    Martínez-Paredes, M.; Alonso-Herrero, A.; Aretxaga, I.; Ramos Almeida, C.; Hernán-Caballero, A.; González-Martín, O.; Pereira-Santaella, M.; Packham, C.; Asensio Ramos, A.; Díaz-Santos, T.; Elitzur, M.; Esquej, P.; García-Bernete, I.; Imanishi, M.; Levenson, N. A.; Rodríguez Espinosa, J. M.

    2015-12-01

    We present an analysis of the nuclear infrared (IR, 1.6-18 μm) emission of the ultraluminous IR galaxy UGC 5101 to derive the properties of its active galactic nucleus (AGN) and its obscuring material. We use new mid-IR high angular resolution (0.3-0.5 arcsec) imaging using the Si-2 filter (λC = 8.7 μm) and 7.5-13 μm spectroscopy taken with CanariCam (CC) on the 10.4 m Gran Telescopio CANARIAS. We also use archival Hubble Space Telescope/NICMOS and Subaru/COMICS imaging and Spitzer/IRS spectroscopy. We estimate the near- and mid-IR unresolved nuclear emission by modelling the imaging data with GALFIT. We decompose the Spitzer/IRS and CC spectra using a power-law component, which represents the emission due to dust heated by the AGN, and a starburst component, both affected by foreground extinction. We model the resulting unresolved near- and mid-IR, and the starburst subtracted CC spectrum with the CLUMPY torus models of Nenkova et al. The derived geometrical properties of the torus, including the large covering factor and the high foreground extinction needed to reproduce the deep 9.7 μm silicate feature, are consistent with the lack of strong AGN signatures in the optical. We derive an AGN bolometric luminosity Lbol ˜ 1.9 × 1045 erg s-1 that is in good agreement with other estimates in the literature.

  6. Detecting dark matter with imploding pulsars in the galactic center.

    PubMed

    Bramante, Joseph; Linden, Tim

    2014-11-01

    The paucity of old millisecond pulsars observed at the galactic center of the Milky Way could be the result of dark matter accumulating in and destroying neutron stars. In regions of high dark matter density, dark matter clumped in a pulsar can exceed the Schwarzschild limit and collapse into a natal black hole which destroys the pulsar. We examine what dark matter models are consistent with this hypothesis and find regions of parameter space where dark matter accumulation can significantly degrade the neutron star population within the galactic center while remaining consistent with observations of old millisecond pulsars in globular clusters and near the solar position. We identify what dark matter couplings and masses might cause a young pulsar at the galactic center to unexpectedly extinguish. Finally, we find that pulsar collapse age scales inversely with the dark matter density and linearly with the dark matter velocity dispersion. This implies that maximum pulsar age is spatially dependent on position within the dark matter halo of the Milky Way. In turn, this pulsar age spatial dependence will be dark matter model dependent.

  7. Detecting dark matter with imploding pulsars in the galactic center.

    PubMed

    Bramante, Joseph; Linden, Tim

    2014-11-01

    The paucity of old millisecond pulsars observed at the galactic center of the Milky Way could be the result of dark matter accumulating in and destroying neutron stars. In regions of high dark matter density, dark matter clumped in a pulsar can exceed the Schwarzschild limit and collapse into a natal black hole which destroys the pulsar. We examine what dark matter models are consistent with this hypothesis and find regions of parameter space where dark matter accumulation can significantly degrade the neutron star population within the galactic center while remaining consistent with observations of old millisecond pulsars in globular clusters and near the solar position. We identify what dark matter couplings and masses might cause a young pulsar at the galactic center to unexpectedly extinguish. Finally, we find that pulsar collapse age scales inversely with the dark matter density and linearly with the dark matter velocity dispersion. This implies that maximum pulsar age is spatially dependent on position within the dark matter halo of the Milky Way. In turn, this pulsar age spatial dependence will be dark matter model dependent. PMID:25415895

  8. The Galactic Magnetic Field as Viewed from the VLA

    NASA Astrophysics Data System (ADS)

    van Eck, Cameron; Brown, Jo-Anne

    2009-05-01

    Interstellar magnetic fields play critical roles in many astrophysical processes. Yet despite their importance, our knowledge about magnetic fields in our Galaxy remains limited. For the field within the Milky Way much of what we do know comes from radio astronomy, through observations of polarization and Faraday rotation measures (RMs) of extragalactic sources and pulsars. A high angular density of RM measurements in several critical areas of the Galaxy is needed to clarify the Galactic magnetic field structure. Understanding the overall structure of the magnetic field will subsequently help us determine the origin and evolution of the field. In an effort to determine the overall structure of the field, Sun et al. (2008) produced 3 models of the Galactic magnetic field based on RM measurements available at the time. These models made distinct predictions for RMs in a region of the inner Galaxy at low Galactic latitude. Using observations made with the Very Large Array (VLA), we have determined RMs for sources in this critical region. In this talk we will present the results of our study and show how the RMs strongly support the ASS+RING model.

  9. Galactic Center Shells and a Recurrent Starburst Model

    NASA Astrophysics Data System (ADS)

    Sofue, Yoshiaki

    2003-04-01

    By applying filtering techniques to remove straight filaments in the 20-cm VLA radio image of the Galactic Center Arc region, we have shown that numerous concentric radio shells of radii 5 to 20pc are surrounding the Pistol and Sickle region, which we call Galactic Center Shells (GCS).Each shell has thermal energy of the order of1049-50erg.Several CO-line shells are associated, whose kinetic energies are of the order of 1049-50erg. Summing up the energies of recognized GCSs, the total energy amounts to ˜ 1051erg.The GCSs show an excellent correlation with the FIR shells observed at 16-26μm with the MSX.We propose a model in which GCSs were produced by recurrent and/or intermittent starbursts in the Pistol area during the last million years.The most recent burst occurred some 105 years ago, producing an inner round-shaped shell (GCS I);earlier ones a million years ago produced outer shells (GCS II and III), which a re more deformed by interactions with the surrounding ISM and Sgr A halo.We argue that recurrent starbursts had also occurred in the past, which produced larger scale hyper-shell structures as well.A burst some million years ago produced the Galactic Center Lobe, and a much stronger one 15 million years ago produced the North Polar Spur.

  10. A CATALOG OF GALACTIC INFRARED CARBON STARS

    SciTech Connect

    Chen, P. S.

    2012-02-15

    We collected almost all of the Galactic infrared carbon stars (IRCSs) from literature published up to the present to organize a catalog of 974 Galactic IRCSs in this paper. Some of their photometric properties in the near-, mid-, and far-infrared are discussed.

  11. Evidence for an old Galactic bulge from RR Lyrae stars in Baade's window - Implications for the formation of the Galaxy and the age of the universe

    NASA Technical Reports Server (NTRS)

    Lee, Young-Wook

    1992-01-01

    Recent abundance measurements of RR Lyrae variables in the Baade's window field of the Galactic nuclear bulge are examined, and the observed metallicity distributions of the RR Lyraes in different Galactic radial zones are compared with those predicted for the HB population models. It is shown that the observed systematic variation with Galactocentric distance is only explained if the age of the stellar population increases, in the mean, with decreasing R(G). Thus, the oldest stellar population, the RR Lyraes in the Galactic nuclear bulge, is indeed older than that in the halo.

  12. THE DIFFERENCES IN THE TORUS GEOMETRY BETWEEN HIDDEN AND NON-HIDDEN BROAD LINE ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Ichikawa, Kohei; Ueda, Yoshihiro; Packham, Christopher; Lopez-Rodriguez, Enrique; Alsip, Crystal D.; Almeida, Cristina Ramos; Ramos, Andrés Asensio; González-Martín, Omaira; Díaz-Santos, Tanio; Elitzur, Moshe; Hönig, Sebastian F.; Imanishi, Masatoshi; Levenson, Nancy A.; Perlman, Eric S.

    2015-04-20

    We present results from the fitting of infrared (IR) spectral energy distributions of 21 active galactic nuclei (AGNs) with clumpy torus models. We compiled high spatial resolution (∼0.3–0.7 arcsec) mid-IR (MIR) N-band spectroscopy, Q-band imaging, and nuclear near- and MIR photometry from the literature. Combining these nuclear near- and MIR observations, far-IR photometry, and clumpy torus models enables us to put constraints on the torus properties and geometry. We divide the sample into three types according to the broad line region (BLR) properties: type-1s, type-2s with scattered or hidden broad line region (HBLR) previously observed, and type-2s without any published HBLR signature (NHBLR). Comparing the torus model parameters gives us the first quantitative torus geometrical view for each subgroup. We find that NHBLR AGNs have smaller torus opening angles and larger covering factors than HBLR AGNs. This suggests that the chance to observe scattered (polarized) flux from the BLR in NHBLR could be reduced by the dual effects of (a) less scattering medium due to the reduced scattering volume given the small torus opening angle and (b) the increased torus obscuration between the observer and the scattering region. These effects give a reasonable explanation for the lack of observed HBLR in some type-2 AGNs.

  13. Anomalous Transport of High Energy Cosmic Rays in Galactic Superbubbles

    NASA Technical Reports Server (NTRS)

    Barghouty, Nasser F.

    2014-01-01

    High-energy cosmic rays may exhibit anomalous transport as they traverse and are accelerated by a collection of supernovae explosions in a galactic superbubble. Signatures of this anomalous transport can show up in the particles' evolution and their spectra. In a continuous-time-random- walk (CTRW) model assuming standard diffusive shock acceleration theory (DSA) for each shock encounter, and where the superbubble (an OB stars association) is idealized as a heterogeneous region of particle sources and sinks, acceleration and transport in the superbubble can be shown to be sub-diffusive. While the sub-diffusive transport can be attributed to the stochastic nature of the acceleration time according to DSA theory, the spectral break appears to be an artifact of transport in a finite medium. These CTRW simulations point to a new and intriguing phenomenon associated with the statistical nature of collective acceleration of high energy cosmic rays in galactic superbubbles.

  14. Directed search for continuous gravitational waves from the Galactic center

    NASA Astrophysics Data System (ADS)

    Aasi, J.; Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Accadia, T.; Acernese, F.; Adams, C.; Adams, T.; Adhikari, R. X.; Affeldt, C.; Agathos, M.; Aggarwal, N.; Aguiar, O. D.; Ajith, P.; Allen, B.; Allocca, A.; Amador Ceron, E.; Amariutei, D.; Anderson, R. A.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C.; Areeda, J.; Ast, S.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Austin, L.; Aylott, B. E.; Babak, S.; Baker, P. T.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barker, D.; Barnum, S. H.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barton, M. A.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J.; Bauchrowitz, J.; Bauer, Th. S.; Bebronne, M.; Behnke, B.; Bejger, M.; Beker, M. G.; Bell, A. S.; Bell, C.; Belopolski, I.; Bergmann, G.; Berliner, J. M.; Bertolini, A.; Bessis, D.; Betzwieser, J.; Beyersdorf, P. T.; Bhadbhade, T.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Bitossi, M.; Bizouard, M. A.; Black, E.; Blackburn, J. K.; Blackburn, L.; Blair, D.; Blom, M.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogan, C.; Bond, C.; Bondu, F.; Bonelli, L.; Bonnand, R.; Bork, R.; Born, M.; Bose, S.; Bosi, L.; Bowers, J.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brannen, C. A.; Brau, J. E.; Breyer, J.; Briant, T.; Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Britzger, M.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brückner, F.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Calderón Bustillo, J.; Calloni, E.; Camp, J. B.; Campsie, P.; Cannon, K. C.; Canuel, B.; Cao, J.; Capano, C. D.; Carbognani, F.; Carbone, L.; Caride, S.; Castiglia, A.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chen, X.; Chen, Y.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Chow, J.; Christensen, N.; Chu, Q.; Chua, S. S. Y.; Chung, S.; Ciani, G.; Clara, F.; Clark, D. E.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Colombini, M.; Constancio, M., Jr.; Conte, A.; Conte, R.; Cook, D.; Corbitt, T. R.; Cordier, M.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M. W.; Coulon, J.-P.; Countryman, S.; Couvares, P.; Coward, D. M.; Cowart, M.; Coyne, D. C.; Craig, K.; Creighton, J. D. E.; Creighton, T. D.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dahl, K.; Dal Canton, T.; Damjanic, M.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dattilo, V.; Daudert, B.; Daveloza, H.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; Dayanga, T.; De Rosa, R.; Debreczeni, G.; Degallaix, J.; Del Pozzo, W.; Deleeuw, E.; Deléglise, S.; Denker, T.; Dent, T.; Dereli, H.; Dergachev, V.; DeRosa, R.; DeSalvo, R.; Dhurandhar, S.; Di Fiore, L.; Di Lieto, A.; Di Palma, I.; Di Virgilio, A.; Díaz, M.; Dietz, A.; Dmitry, K.; Donovan, F.; Dooley, K. L.; Doravari, S.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Dumas, J.-C.; Dwyer, S.; Eberle, T.; Edwards, M.; Effler, A.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Endrőczi, G.; Essick, R.; Etzel, T.; Evans, K.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst, S.; Fang, Q.; Farr, B.; Farr, W.; Favata, M.; Fazi, D.; Fehrmann, H.; Feldbaum, D.; Ferrante, I.; Ferrini, F.; Fidecaro, F.; Finn, L. S.; Fiori, I.; Fisher, R.; Flaminio, R.; Foley, E.; Foley, S.; Forsi, E.; Forte, L. A.; Fotopoulos, N.; Fournier, J.-D.; Franco, S.; Frasca, S.; Frasconi, F.; Frede, M.; Frei, M.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fujimoto, M.-K.; Fulda, P.; Fyffe, M.; Gair, J.; Gammaitoni, L.; Garcia, J.; Garufi, F.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; Gergely, L.; Ghosh, S.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Giazotto, A.; Gil-Casanova, S.; Gill, C.; Gleason, J.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gordon, N.; Gorodetsky, M. L.; Gossan, S.; Goßler, S.; Gouaty, R.; Graef, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Griffo, C.; Grote, H.; Grover, K.; Grunewald, S.; Guidi, G. M.; Guido, C.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hall, B.; Hall, E.; Hammer, D.; Hammond, G.; Hanke, M.; Hanks, J.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G. M.; Harry, I. W.; Harstad, E. D.; Hartman, M. T.; Haughian, K.; Hayama, K.; Heefner, J.; Heidmann, A.; Heintze, M.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Holt, K.; Holtrop, M.; Hong, T.; Hooper, S.; Horrom, T.; Hosken, D. J.; Hough, J.; Howell, E. J.; Hu, Y.; Hua, Z.; Huang, V.; Huerta, E. A.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh, M.; Huynh-Dinh, T.; Iafrate, J.; Ingram, D. R.

    2013-11-01

    We present the results of a directed search for continuous gravitational waves from unknown, isolated neutron stars in the Galactic center region, performed on two years of data from LIGO’s fifth science run from two LIGO detectors. The search uses a semicoherent approach, analyzing coherently 630 segments, each spanning 11.5 hours, and then incoherently combining the results of the single segments. It covers gravitational wave frequencies in a range from 78 to 496 Hz and a frequency-dependent range of first-order spindown values down to -7.86×10-8Hz/s at the highest frequency. No gravitational waves were detected. The 90% confidence upper limits on the gravitational wave amplitude of sources at the Galactic center are ˜3.35×10-25 for frequencies near 150 Hz. These upper limits are the most constraining to date for a large-parameter-space search for continuous gravitational wave signals.

  15. Statistical Diagnostics to Identify Galactic Foregrounds in B -Mode Maps

    NASA Astrophysics Data System (ADS)

    Kamionkowski, Marc; Kovetz, Ely D.

    2014-11-01

    Recent developments in the search for inflationary gravitational waves in the cosmic microwave background polarization motivate the search for new diagnostics to distinguish the Galactic foreground contribution to B modes from the cosmic signal. We show that B modes from these foregrounds should exhibit a local hexadecapolar departure in power from statistical isotropy (SI). We present a simple algorithm to search for a uniform SI violation of this sort, as may arise in a sufficiently small patch of sky. We then show how to search for these effects if the orientation of the SI violation varies across the survey region, as is more likely to occur in surveys with more sky coverage. If detected, these departures from Gaussianity would indicate some level of Galactic foreground contamination in the B -mode maps. Given uncertainties about foreground properties, though, caution should be exercised in attributing a null detection to an absence of foregrounds.

  16. Karyopherin-Mediated Nuclear Import of the Homing Endonuclease VMA1-Derived Endonuclease Is Required for Self-Propagation of the Coding Region

    PubMed Central

    Nagai, Yuri; Nogami, Satoru; Kumagai-Sano, Fumi; Ohya, Yoshikazu

    2003-01-01

    VMA1-derived endonuclease (VDE), a site-specific endonuclease in Saccharomyces cerevisiae, enters the nucleus to generate a double-strand break in the VDE-negative allelic locus, mediating the self-propagating gene conversion called homing. Although VDE is excluded from the nucleus in mitotic cells, it relocalizes at premeiosis, becoming localized in both the nucleus and the cytoplasm in meiosis. The nuclear localization of VDE is induced by inactivation of TOR kinases, which constitute central regulators of cell differentiation in S. cerevisiae, and by nutrient depletion. A functional genomic approach revealed that at least two karyopherins, Srp1p and Kap142p, are required for the nuclear localization pattern. Genetic and physical interactions between Srp1p and VDE imply direct involvement of karyopherin-mediated nuclear transport in this process. Inactivation of TOR signaling or acquisition of an extra nuclear localization signal in the VDE coding region leads to artificial nuclear localization of VDE and thereby induces homing even during mitosis. These results serve as evidence that VDE utilizes the host systems of nutrient signal transduction and nucleocytoplasmic transport to ensure the propagation of its coding region. PMID:12588991

  17. Nuclear reactions with 14 MeV neutrons and bremsstrahlungs in giant dipole resonance (GDR) region using small accelerators

    NASA Astrophysics Data System (ADS)

    Thiep, Tran Duc; Van Do, Nguyen; An, Truong Thi; Son, Nguyen Ngoc

    2003-07-01

    In 1974 an accelerator of deterium, namely neutron generator NA-3-C was put into operation and in 1982 another accelerator of electron Microtron MT-17 started its work in the Institute of Physics. Though very modest these accelerators are useful for developing countries as Vietnam in both Nuclear Physics Research and Training. In this report we present some results obtained in studies on Nuclear Data, Nuclear Reactions as well as nuclear activation analysis methods. We also would like to discuss about the possibilities of collaboration in the future.

  18. The diffuse galactic gamma radiation: The Compton contribution and component separation by energy interval and galactic coordinates

    NASA Technical Reports Server (NTRS)

    Kniffen, D. A.; Fichtel, C.

    1981-01-01

    The radiation to be expected from cosmic ray interactions with matter and photons was examined. Particular emphasis is placed on the Compton emission. Both the photon density in and near the visible region and that in the region are deduced from the estimates of the emission functions throughout the Galaxy. The blackbody radiation is also included in the estimate of the total Compton emission. The result suggests that the gamma ray Compton radiation from cosmic ray ineractions with galactic visible and infrared photons is substantially larger than previously believed.

  19. Galactic Center Fly-in

    NASA Astrophysics Data System (ADS)

    Hanson, A.; Fu, C.-W.; Li, Y.; Frisch, P. C.

    2006-06-01

    Beginning with the familiar constellations of the night sky, we present a multispectral zoom into the core of the Milky Way Galaxy. After traveling over seven orders of magnitude in spatial scale, we discover the violent phenomena occurring within one light year of the Black Hole at the Galactic Core. This animated zoom includes data with wavelengths from radio to X-ray, and is based entirely on data or models that have been aligned at all spatial scales in order to provide a single continuous visual trip into the Center of the Milky Way Galaxy. The visualization challenge has been to align and choreograph data acquired over a wide range of wavelength and spatial scales, and obtain a new scientific as well as educational perspective of the dense core of our Galaxy.

  20. Theory of active galactic nuclei

    NASA Technical Reports Server (NTRS)

    Shields, G. A.

    1986-01-01

    The involvement of accretion disks around supermassive black holes in the theory of active galactic nuclei (AGN) is discussed. The physics of thin and thick accretion disks is discussed and the partition between thermal and nonthermal energy production in supermassive disks is seen as uncertain. The thermal limit cycle may operate in supermassive disks (Shields, 1985), with accumulation of gas in the disk for periods of 10 to the 4th to 10 to the 7th years, punctuated by briefer outbursts during which the mass is rapidly transferred to smaller radii. An extended X-ray source in AGN is consistent with observations (Tennant and Mushotsky, 1983), and a large wind mass loss rate exceeding the central accretion rate means that only a fraction of the mass entering the disk will reach the central object; the rest being lost to the wind. Controversy in the relationship between the broad lines and the disk is also discussed.