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Journal articles on the topic 'North Polar Spur (NPS)'

Author: Grafiati

Published: 6 September 2023

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1

Das, Kaustav K., Catherine Zucker, Joshua S. Speagle, Alyssa Goodman, Gregory M. Green, and João Alves. "Constraining the distance to the North Polar Spur with Gaia DR2." Monthly Notices of the Royal Astronomical Society 498, no. 4 (September 7, 2020): 5863–72. http://dx.doi.org/10.1093/mnras/staa2702.

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ABSTRACT The North Polar Spur (NPS) is one of the largest structures observed in the Milky Way in both the radio and soft X-rays. While several predictions have been made regarding the origin of the NPS, modelling the structure is difficult without precise distance constraints. In this paper, we determine accurate distances to the southern terminus of the NPS and towards latitudes ranging up to 55°. First, we fit for the distance and extinction to stars towards the NPS using optical and near-infrared photometry and Gaia Data Release 2 astrometry. We model these per-star distance–extinction estimates as being caused by dust screens at unknown distances, which we fit for using a nested sampling algorithm. We then compare the extinction to the Spur derived from our 3D dust modelling with integrated independent measures from XMM–Newton X-ray absorption and H i column density measures. We find that we can account for nearly 100 per cent of the total column density of the NPS as lying within 140 pc for latitudes >26° and within 700 pc for latitudes <11°. Based on the results, we conclude that the NPS is not associated with the Galactic Centre or the Fermi bubbles. Instead, it is likely associated, especially at higher latitudes, with the Scorpius–Centaurus association.

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Sofue, Yoshiaki, and Jun Kataoka. "Interaction of the galactic-centre super bubbles with the gaseous disc." Monthly Notices of the Royal Astronomical Society 506, no. 2 (July 2, 2021): 2170–80. http://dx.doi.org/10.1093/mnras/stab1857.

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ABSTRACT The interaction of Galactic centre (GC) super bubbles (GSBs) with the gaseous disc and halo of the Milky Way is investigated using radio continuum, X-ray, H i, and CO line surveys. The radio North Polar Spur (NPS) constitutes the brightest eastern ridge of GSB, brightening towards the galactic plane and reaching l = 22○, b = +2○ at the sharpest end, where it intersects the tangential direction of the 3-kpc-expanding ring and crater. Examination of the spur ridges reveals that the entire GSB, including the NPS and its counter spurs, constitutes a GC-symmetrical Ω/ Ʊ shape. The thickness and gas density of the H i and CO discs are shown to increase sharply from the inside (lower longitude) to the outside the 3-kpc crater. Formation of crater is explained by the sweeping of the upper layer of disc gas by the shock wave from the GC by the explosion ∼10 My ago with the emitted energy of several 1055 erg. Based on the discussion, a unified view on the structure and formation mechanism of GSB is presented.

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3

Yamamoto, Marino, Jun Kataoka, and Yoshiaki Sofue. "Discovery of non-equilibrium ionization plasma associated with the North Polar Spur and Loop I." Monthly Notices of the Royal Astronomical Society 512, no. 2 (March 4, 2022): 2034–43. http://dx.doi.org/10.1093/mnras/stac577.

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ABSTRACT We investigated the detailed plasma condition of the North Polar Spur (NPS)/Loop I using archival Suzaku data. In previous research, collisional ionization equilibrium (CIE) have been assumed for X-ray plasma state, but we also assume non-equilibrium ionization (NEI) to check the plasma condition in more detail. We found that most of the plasma in the NPS/Loop I favors the state of NEI, and has the density-weighted ionization timescale of net ∼ 1011–12 s cm−3 and the electron number density ne ∼ a few × 10−3 cm−3. The plasma shock age, t, or the time elapsed after the shock front passed through the plasma, is estimated to be on the order of a few $\rm {Myr}$ for the NPS/Loop I, which puts a strict lower limit to the age of the whole NPS/Loop I structure. We found that NEI results in significantly higher temperature and lower emission measure than those currently derived under CIE assumption. The electron temperature under NEI is estimated to be as high as 0.5 keV toward the brightest X-ray NPS ridge at Δθ = −20○, which decreases to 0.3 keV at −10○, and again increases to ∼0.6 keV towards the outer edge of Loop I at Δθ ∼ 0○, about twice the currently estimated temperatures. Here, Δθ is the angular distance from the outer edge of Loop I. We discuss the implication of introducing NEI for the research in plasma states in astrophysical phenomena.

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4

West, J. L., T. L. Landecker, B. M. Gaensler, T. Jaffe, and A. S. Hill. "A Unified Model for the Fan Region and the North Polar Spur: A Bundle of Filaments in the Local Galaxy." Astrophysical Journal 923, no. 1 (December 1, 2021): 58. http://dx.doi.org/10.3847/1538-4357/ac2ba2.

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Abstract We present a simple, unified model that can explain two of the brightest, large-scale, diffuse, polarized radio features in the sky, the North Polar Spur (NPS) and the Fan Region, along with several other prominent loops. We suggest that they are long, magnetized, and parallel filamentary structures that surround the Local arm and/or Local Bubble, in which the Sun is embedded. We show that this model is consistent with the large number of observational studies on these regions and is able to resolve an apparent contradiction in the literature that suggests that the high-latitude portion of the NPS is nearby, while lower-latitude portions are more distant. Understanding the contributions of this local emission is critical to developing a complete model of the Galactic magnetic field. These very nearby structures also provide context to help understand similar nonthermal, filamentary structures that are increasingly being observed with modern radio telescopes.

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5

Kataoka, Jun, Yoshiaki Sofue, Yoshiyuki Inoue, Masahiro Akita, Shinya Nakashima, and Tomonori Totani. "X-Ray and Gamma-Ray Observations of the Fermi Bubbles and NPS/Loop I Structures." Galaxies 6, no. 1 (February 26, 2018): 27. http://dx.doi.org/10.3390/galaxies6010027.

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The Fermi bubbles were possibly created by large injections of energy into the Galactic Center (GC), either by an active galactic nucleus (AGN) or by nuclear starburst more than ~10 Myr ago. However, the origin of the diffuse gamma-ray emission associated with Loop I, a radio continuum loop spanning across 100° on the sky, is still being debated. The northern-most part of Loop I, known as the North Polar Spur (NPS), is the brightest arm and is even clearly visible in the ROSAT X-ray sky map. In this paper, we present a comprehensive review on the X-ray observations of the Fermi bubbles and their possible association with the NPS and Loop I structures. Using uniform analysis of archival Suzaku and Swift data, we show that X-ray plasma with kT~0.3 keV and low metal abundance (Z~0.2 Z◉) is ubiquitous in both the bubbles and Loop I and is naturally interpreted as weakly shock-heated Galactic halo gas. However, the observed asymmetry of the X-ray-emitting gas above and below the GC has still not been resolved; it cannot be fully explained by the inclination of the axis of the Fermi bubbles to the Galactic disk normal. We argue that the NPS and Loop I may be asymmetric remnants of a large explosion that occurred before the event that created the Fermi bubbles, and that the soft gamma-ray emission from Loop I may be due to either π0 decay of accelerated protons or electron bremsstrahlung.

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6

Sofue, Yoshiaki. "The North Polar Spur and Aquila Rift." Monthly Notices of the Royal Astronomical Society 447, no. 4 (January 29, 2015): 3824–31. http://dx.doi.org/10.1093/mnras/stu2661.

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7

Miroshnichenko, A. P. "THE NORTH POLAR SPUR AS OUR GALAXY JET." Radio Physics and Radio Astronomy 1, no. 2 (2010): 93–98. http://dx.doi.org/10.1615/radiophysicsradioastronomy.v1.i2.10.

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8

LaRocca, Daniel M., Philip Kaaret, K. D. Kuntz, Edmund Hodges-Kluck, Anna Zajczyk, Jesse Bluem, Rebecca Ringuette, and Keith M. Jahoda. "An Analysis of the North Polar Spur Using HaloSat." Astrophysical Journal 904, no. 1 (November 20, 2020): 54. http://dx.doi.org/10.3847/1538-4357/abbdfd.

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9

Willingale, R., A. D. P. Hands, R. S. Warwick, S. L. Snowden, and D. N. Burrows. "The X-ray spectrum of the North Polar Spur." Monthly Notices of the Royal Astronomical Society 343, no. 3 (August 11, 2003): 995–1001. http://dx.doi.org/10.1046/j.1365-8711.2003.06741.x.

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10

Miller, Eric D., Hiroshi Tsunemi, Mark W. Bautz, Dan McCammon, Ryuichi Fujimoto, John P. Hughes, Satoru Katsuda, et al. "Suzaku Observations of the North Polar Spur: Evidence for Nitrogen Enhancement." Publications of the Astronomical Society of Japan 60, sp1 (February 20, 2008): S95—S106. http://dx.doi.org/10.1093/pasj/60.sp1.s95.

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11

Park, J. W., K. W. Min, K. I. Seon, I. J. Kim, Y. M. Lim, W. Han, U. W. Nam, et al. "Far-Ultraviolet Observations of the Loop I/North Polar Spur Region." Astrophysical Journal 665, no. 1 (July 26, 2007): L39—L42. http://dx.doi.org/10.1086/521046.

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12

Wolleben, M. "A New Model for the Loop I (North Polar Spur) Region." Astrophysical Journal 664, no. 1 (July 20, 2007): 349–56. http://dx.doi.org/10.1086/518711.

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13

Milogradov-Tuin, Jelena. "Loop I (the north Polar Spur) region - a quasi radio halo." Symposium - International Astronomical Union 106 (1985): 245–46. http://dx.doi.org/10.1017/s007418090024254x.

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The distribution of total spectral indices between 38 and 408 MHz with a resolution of for δ>-25° has the following main properties:1. Relatively small variations of spectral indices over the sky.2. High indices in the central region at high galactic latitudes.3. Moderately low spectral indices in the anticentre region.4. Lower indices in the low-brightness regions (cold holes).5. The lowest indices in regions containing large amounts of HII.

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14

Gu, Liyi, Junjie Mao, Elisa Costantini, and Jelle Kaastra. "SuzakuandXMM-Newtonobservations of the North Polar Spur: Charge exchange or ISM absorption?" Astronomy & Astrophysics 594 (October 2016): A78. http://dx.doi.org/10.1051/0004-6361/201628609.

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15

Lallement, R., S. Snowden, K. D. Kuntz, T. M. Dame, D. Koutroumpa, I. Grenier, and J. M. Casandjian. "On the distance to the North Polar Spur and the local CO-H2factor." Astronomy & Astrophysics 595 (November 2016): A131. http://dx.doi.org/10.1051/0004-6361/201629453.

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16

Verschuur, G. L., and T. A. Th Spoelstra. "The Need for High Resolution for Polarization Studies of Galactic Background Radiation." Symposium - International Astronomical Union 140 (1990): 62. http://dx.doi.org/10.1017/s0074180900189557.

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Polarization data at 390 and 826 MHz were obtained with the 300-foot telescope in February 1987. A survey of selected regions of sky planned for December 1988 had to be postponed. However, our limited data at 390 MHz show that the 30′ beam detected polarization temperatures between four to six times larger than found in surveys with a 1.3 arcmin resolution. This was true in both the highly polarized region around 1=140 degrees and in the North Polar Spur where polarization structures appear to be unresolved (<0.9 pc at the distance of the spur). High resolution observations will be critical to our understanding of the interstellar magnetic field and the scale-length of depolarizing structures.

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Sun, X. H., T. L. Landecker, B. M. Gaensler, E. Carretti, W. Reich, J. P. Leahy, N. M. McClure-Griffiths, et al. "FARADAY TOMOGRAPHY OF THE NORTH POLAR SPUR: CONSTRAINTS ON THE DISTANCE TO THE SPUR AND ON THE MAGNETIC FIELD OF THE GALAXY." Astrophysical Journal 811, no. 1 (September 16, 2015): 40. http://dx.doi.org/10.1088/0004-637x/811/1/40.

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18

Sarkar, Kartick C. "Possible connection between the asymmetry of the North Polar Spur and Loop I and Fermi bubbles." Monthly Notices of the Royal Astronomical Society 482, no. 4 (November 28, 2018): 4813–23. http://dx.doi.org/10.1093/mnras/sty2944.

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19

Rand, R. J., and S. R. Kulkarni. "Structure of the Local Galactic Magnetic Field." Symposium - International Astronomical Union 140 (1990): 44–46. http://dx.doi.org/10.1017/s007418090018948x.

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We have modeled the local Galactic magnetic field using pulsar rotation measures (RMs), of which there are now about 200 available. The North Polar Spur has a significant effect on pulsar RMs. Using RMs of 116 pulsars nearer than 3 kpc, we find that the local field has a strength B0 = 1.6 ± 0.2 μG toward longitude lB =96° ± 4°, with a reversal of the field at a distance Dr = 600 ± 80 pc toward the inner Galaxy. Relaxing the 3 kpc distance restriction, we find that a concentric ring model with reversals is superior to a bisymmetric spiral model as a fit to the data.

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20

Lallement, Rosine. "North Polar Spur/Loop I: gigantic outskirt of the Northern Fermi bubble or nearby hot gas cavity blown by supernovae?" Comptes Rendus. Physique 23, S2 (March 8, 2022): 1–24. http://dx.doi.org/10.5802/crphys.97.

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21

Rothenflug, R. "Features in the Soft X-ray Background." International Astronomical Union Colloquium 115 (1990): 146–55. http://dx.doi.org/10.1017/s0252921100012252.

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AbstractThe soft X-ray background is explained in terms of emission coming from hot gas. Most of these soft X-ray data were obtained by proportional counters with a poor energy resolution. Instruments having the capability to resolve lines were only flown by two groups: a GSPC by a Japanese group and a SSD by a french-american collaboration. They both detected the 0 VII line emission coming from the soft X-ray background and so proved the thermal nature of the emission. The implications of these results on possible models for the local hot medium will be discussed. The same detectors observed part of the North Polar Spur. They detected emission lines coming from different species (0 VII,Fe XVII,Ne IX). Spatial variations of line ratios for this object could be due to non-equilibrium ionization effects.

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22

Neiman, V. G. "To the projects and challenges of domestic hydrophysical study of the global ocean’s polar regions." Journal of Oceanological Research 48, no. 1 (April 30, 2020): 5–26. http://dx.doi.org/10.29006/1564-2291.jor-2020.48(1).1.

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One of the climatically significant, but the poor studied hydrophysical factor in the polar regions of the world ocean is the subsurface layer of relatively warm seawater of subtropical origin. In the Arctic Ocean, this layer is associated with the waters of the Gulfstream, the highlatitude continuation of which in the form of a spur of the North Atlantic current penetrates into the Arctic basin, where it sinks to the depth of its density and spreads throughout its vast space in the layer of 100–900 m. The existence of a subsurface layer with an anomalous inversion vertical profile of water temperature also occurs in the Southern ocean. The article discusses the problem of monitoring the dynamics of this layer and obtaining data from a field experiment on its interaction with the atmosphere in the context of the to-day climate change of the Arctic and Antarctic. There is a reason to hope that the planned development of modern Russian scientific research in the polar regions of the world ocean will help to solve this important climatic problem. The paper presents some key results of this kind of domestic oceanological studies of the mid-twentieth century, which made a significant contribution to the theory and experiment related to the dynamics of the Southern ocean.

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23

Panopoulou, G. V., C. Dickinson, A. C. S. Readhead, T. J. Pearson, and M. W. Peel. "Revisiting the Distance to Radio Loops I and IV Using Gaia and Radio/Optical Polarization Data." Astrophysical Journal 922, no. 2 (December 1, 2021): 210. http://dx.doi.org/10.3847/1538-4357/ac273f.

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Abstract Galactic synchrotron emission exhibits large angular scale features known as radio spurs and loops. Determining the physical size of these structures is important for understanding the local interstellar structure and for modeling the Galactic magnetic field. However, the distance to these structures is either under debate or entirely unknown. We revisit a classical method of finding the location of radio spurs by comparing optical polarization angles with those of synchrotron emission as a function of distance. We consider three tracers of the magnetic field: stellar polarization, polarized synchrotron radio emission, and polarized thermal dust emission. We employ archival measurements of optical starlight polarization and Gaia distances and construct a new map of polarized synchrotron emission from WMAP and Planck data. We confirm that synchrotron, dust emission, and stellar polarization angles all show a statistically significant alignment at high Galactic latitude. We obtain distance limits to three regions toward Loop I of 112 ± 17 pc, 135 ± 20 pc, and <105 pc. Our results strongly suggest that the polarized synchrotron emission toward the North Polar Spur at b > 30° is local. This is consistent with the conclusions of earlier work based on stellar polarization and extinction, but in stark contrast with the Galactic center origin recently revisited on the basis of X-ray data. We also obtain a distance measurement toward part of Loop IV (180 ± 15 pc) and find evidence that its synchrotron emission arises from chance overlap of structures located at different distances. Future optical polarization surveys will allow the expansion of this analysis to other radio spurs.

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24

Soto, Christian, Trisha Ashley, Andrew J. Fox, and Rongmon Bordoloi. "The Signature of the Northern Galactic Center Region in Low-velocity UV Absorption." Astrophysical Journal 954, no. 1 (August 23, 2023): 64. http://dx.doi.org/10.3847/1538-4357/ace597.

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Abstract The Galactic Center (GC) is surrounded by plasma lobes that extend up to ∼14 kpc above and below the plane. Until now, UV absorption studies of these lobes have only focused on high-velocity components (∣v LSR∣ > 100 km s−1) because low- and intermediate-velocity (LIV) components (∣v LSR∣ < 100 km s−1) are blended with foreground interstellar medium. To overcome this difficulty, we present a differential experiment to compare the LIV absorption between different structures within the GC region, including the Fermi Bubbles (FBs; seen in gamma rays), the eROSITA Bubbles (eBs; seen in X-rays), and the Loop I North Polar Spur (LNPS) association, an X-ray and radio feature within the northern eB. We use far-UV spectra from Hubble Space Telescope to measure LIV Si iv absorption in 61 active galactic nuclei sight lines, of which 21 pass through the FBs, 53 pass through the eBs, and 18 pass through the LNPS. We also compare our measurements to those in the literature from sight lines covering the disk–halo interface and circumgalactic medium (CGM). We find that the FBs and eBs have enhancements in measured columns of 0.22–0.29 dex in log. We also remove the contribution of a modeled disk and CGM component from the measured Si iv columns and find that the northern eB still retains a Si iv enhancement of 0.62 dex in log. A similar enhancement is not seen in the southern eB. Since a notable difference between the northern and southern eBs is the presence of the LNPS association in the nothern bubble, the northern eB enhancement may be caused by the LNPS.

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25

Sonett, C. P. "A Supernova Shock Ensemble Model Using Vostok 10Be Radioactivity." Radiocarbon 34, no. 2 (1992): 239–45. http://dx.doi.org/10.1017/s0033822200013680.

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Analysis of the Vostok ice-core record of 10Be (Raisbeck et al. 1987) suggests that the sharply resolved increases in 10Be at 35 ka (kyr) and 60 ka are due to cosmic-ray (CR) increases. As an alternate to long-term solar modulation or strong decreases in the Earth's magnetic field, supernova (SN) forcing is qualitatively consistent with the generation of a forward-reverse shock ensemble from a spherical blast wave of age very approximately at 75 ka. This age agrees with Davelaar, Bleeker and Deerenberg's (1980) identification of 75 ka for the age of a North Polar Spur SN remnant. Confirmation would be the first geochemical detection of supernova forcing of spallogenic and perhaps cosmogenic isotope production in the atmosphere. The three 10Be increases can be satisfied by a modification of the Sonett, Morfill, and Jokipii (1987) model. This consists of 2 or 3 shock waves from a single SN event, which includes the first stage in the expansion, leading to a forward shock, S1+, and a pair of reverse waves, S1− and S2−. One reverse wave arises from the spherical expansion, itself, and the other is a reflected wave from a remnant precursor shell boundary from a more ancient SN. The model requires the solar system to be immersed in the ‘bubble’ of the earlier post-SN evolution, possibly affecting estimates of heliospheric boundary distance. However more recent analysis of Camp Century ice core data discloses only the 35 ka 10Be peak. This recent result compounds the difficulty of constructing a completely consistent model for the source of the Vostok spikes. This paper is written in the spirit of suggesting only one of possibly several different models, even within the subclass of SN models.

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26

Lallement, R., L. Capitanio, L. Ruiz-Dern, C. Danielski, C. Babusiaux, L. Vergely, M. Elyajouri, F. Arenou, and N. Leclerc. "Three-dimensional maps of interstellar dust in the Local Arm: using Gaia, 2MASS, and APOGEE-DR14." Astronomy & Astrophysics 616 (August 2018): A132. http://dx.doi.org/10.1051/0004-6361/201832832.

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Context. Gaia data and stellar surveys open the way to the construction of detailed 3D maps of the Galactic interstellar (IS) dust based on the synthesis of star distances and extinctions. Dust maps are tools of broad use, also for Gaia-related Milky Way studies. Aims. Reliable extinction measurements require very accurate photometric calibrations. We show the first step of an iterative process linking 3D dust maps and photometric calibrations, and improving them simultaneously. Methods. Our previous 3D map of nearby IS dust was used to select low-reddening SDSS/APOGEE-DR14 red giants, and this database served for an empirical effective temperature- and metallicity-dependent photometric calibration in the Gaia G and 2MASS Ks bands. This calibration has been combined with Gaia G-band empirical extinction coefficients recently published, G, J, and Ks photometry and APOGEE atmospheric parameters to derive the extinction of a large fraction of the survey targets. Distances were estimated independently using isochrones and the magnitude-independent extinction KJ−Ks. This new dataset has been merged with the one used for the earlier version of dust map. A new Bayesian inversion of distance-extinction pairs has been performed to produce an updated 3D map. Results. We present several properties of the new map. A comparison with 2D dust emission reveals that all large dust shells seen in emission at middle and high latitudes are closer than 300 pc. The updated distribution constrains the well-debated, X-ray bright North Polar Spur to originate beyond 800 pc. We use the Orion region to illustrate additional details and distant clouds. On the large scale the map reveals a complex structure of the Local Arm. Chains of clouds of 2–3 kpc in length appear in planes tilted by ≃15° with respect to the Galactic plane. A series of cavities oriented along a l ≃ 60–240° axis crosses the Arm. Conclusions. The results illustrate the ongoing synergy between 3D mapping of IS dust and stellar calibrations in the context of Gaia. Dust maps provide prior foregrounds for future calibrations appropriate to different target characteristics or ranges of extinction, allowing us in turn to increase extinction data and produce more detailed and extended maps.

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Fabian, Stanislaus G., Stephen J. Gallagher, and David De Vleeschouwer. "British–Irish Ice Sheet and polar front history of the Goban Spur, offshore southwest Ireland over the last 250 000 years." Boreas, August 10, 2023. http://dx.doi.org/10.1111/bor.12631.

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Deep Sea Drilling Program (DSDP) Site 548 was cored in 1984 at a water depth of 1256 m on the Goban Spur, offshore southwest Ireland. Coring retrieved a ~100‐m‐thick Pleistocene contourite sequence. This study uses planktonic foraminiferal assemblage and benthic foraminiferal oxygen isotope analyses to establish an age model for the upper 40 m of this core. This site's multidisciplinary analyses of planktonic foraminiferal assemblages, lithic grains, facies and calcium carbonate concentration reveal a 250 000‐year record of the North Atlantic polar front variability and British–Irish Ice Sheet (BIIS) history. The sequence is characterized by alternations of ice rafted debris (IRD) laden pelagic mud facies with calcium carbonate‐rich silty sand contourite facies that track glacial/interglacial cycles. The polar front migrated southward across the area several times during glacial maxima and stadial periods, while warmer Mediterranean Outflow Water (MOW) flowed northward across the region during interglacial and interstadial periods depositing contourites. Lithic analyses reveal a complex history of IRD deposition associated with iceberg calving from the Laurentide Ice Sheet and northwest European ice sheets, mainly the BIIS. Comparison between the Goban Spur (DSDP Site 548) and the Celtic Margin (MD03‐2692) and central North Atlantic Integrated Ocean Drilling Program (IODP) Site U1308 suggests differences between the ‘non‐Laurentide Ice Sheet’ Heinrich Events (HE) 6 and 3 at the Goban Spur, with IRD from the BIIS being prominent during HE 6 and IRD from other European ice sheets north of the BIIS likely being more dominant during HE 3. The nature of lithics in IRD‐rich horizons during Terminations 3, 3A, 2 and 1 suggests significant iceberg calving episodes preceding BIIS retreat during the onset of interstadial intervals.

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Mou, G., J. Wu, and Y. Sofue. "Cosmic ray electrons accounting for the North polar spur and the acceleration efficiency of weak shocks." Astronomy & Astrophysics, July 20, 2023. http://dx.doi.org/10.1051/0004-6361/202245401.

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29

Sofue, Yoshiaki. "Giant H i hole inside the 3 kpc ring and the North Polar Spur—The Galactic crater." Publications of the Astronomical Society of Japan 69, no. 5 (October 1, 2017). http://dx.doi.org/10.1093/pasj/psx067.

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30

Funck, Thomas, and John Shimeld. "Crustal structure and magmatism of the Marvin Spur and northern Alpha Ridge, Arctic Ocean." Geophysical Journal International, December 12, 2022. http://dx.doi.org/10.1093/gji/ggac480.

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Summary The Marvin Spur is a 450-km-long east–west trending escarpment along the northernmost periphery of the Alpha Ridge, starting about 500 km from the coasts of Ellesmere Island and Greenland off the Arctic Ocean margin of North America and running subparallel to the Amerasian margin of the continental Lomonosov Ridge. This region was investigated as part of the Canada-Sweden Polar Expedition in 2016, from which two seismic profiles are presented. The first is a 165-km-long line along the crest of the Marvin Spur. The second is a 221-km-long line extending southwestward from the spur to the northern flank of the Alpha Ridge within the Cretaceous High Arctic Large Igneous Province (HALIP). Multichannel seismic reflection data were acquired along both lines using a 100-m-long streamer, and the airgun shots were also recorded using 16 sonobuoys and 5 stations on the sea ice to calculate a velocity model for the crust from forward modelling of seismic travel times. The Marvin Spur profile reveals up to 1100 m of sedimentary rocks on top of a 1-km-thick series of basalts (4.5–5.1 km s−1). Upper and lower crust have velocities of 5.8–5.9 km s−1 and 6.2–6.3 km s−1, respectively, with the upper crust being 1–2 km thick compared to around 13 km for the lower crust. A wide-angle double seismic reflection manifests the top and base of a 6-km-thick lower crustal layer that we interpret as magmatic underplating beneath the continental crust of the Marvin Spur. We correlate a high-amplitude magnetic anomaly on Marvin Spur with a comparable anomaly on Lomonosov Ridge by invoking 110 km of dextral strike-slip motion. Assuming that HALIP-related magmatic deposits generate these anomalies, the strike-slip motion pre-dates the main phase of magmatism (latest Cretaceous, 78 Ma). On the northern Alpha Ridge, sediments are around 1-km-thick and cover a 700 to 1700-m-thick series of basalts with velocities of 4.4 to 4.8 km s−1. Below is a 3-km-thick layer with intermediate velocities of 5.6 km s−1 and a lower crust with a velocity of 6.8 km s−1. Moho depth is not resolved seismically, but gravity modelling indicates a total thickness of 13 or 18 km for the igneous crust except for the Fedotov Seamount where Moho deepens by about 5 km. Construction of the seamount occurred in multiple magmatic phases, including flow eruptions during deposition of the Cenozoic sedimentary succession post-dating the main HALIP magmatism.

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"B. Radio Studies." Transactions of the International Astronomical Union 19, no. 1 (1985): 409–16. http://dx.doi.org/10.1017/s0251107x00006465.

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Several regional surveys of southern HI made with the Argentine 100-m telescope were published (30.155.031). HI and other data were used by Dolidze (30.155. 044) to study the local distribution of gas and star forming regions. The Perseus arm region was the subject of an analogous study by Gerasimenko (34.155.139). Vallée (34.155.005) used rotation measure data from extragalactic sources in the direction of the Perseus arm to determine the magnetic field structure there and to constrain gravitational collapse theories of magnetic compression. HI in the direction of the Puppis window was surveyed by Stacy and Jackson (32.131.277) and used to study the turbulent characteristics of the interstellar medium. HI related to Gould“s Belt was studied by Pöppel and Olano (32.155.024, 33.155.030). Salter (34. 131.014) reviewed radio and other observations pertaining tc Loop I, the North Polar Spur, and considered the influence which this structure might have on the local medium.

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32

Thai, Tran Thanh, Nguyen Le Que Lam, Nguyen Thi My Yen, and Ngo Xuan Quang. "Correlation between Oxygen Demand of Nematode Communities with Dissolved Oxygen in the Organic Shrimp Farming Ponds, Ca Mau Province." VNU Journal of Science: Natural Sciences and Technology 34, no. 1 (March 23, 2018). http://dx.doi.org/10.25073/2588-1140/vnunst.4717.

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Dissolved oxygen (DO), total biomass and oxygen demand of nematode communities in the organic shrimp farms located in Tam Giang commune, Nam Can District, Ca Mau province were investigated in three seasons (March-dry, July-transfer and November-wet season) of 2015. The results showed that most of DO values were within permissible limits. However, the frequency distributions of DO values are very compressed at the lower limit of their scale. Total dry biomass varied from 24.77 to 937.04 µgC/10cm2 while oxygen demand ranged from 3467.39 to 64288.50 nlO2/day/10cm2. These values were slightly high when compared to other studies in the world. The following results recorded that the negatively correlation between DO and oxygen demand of nematode communities in the organic shrimp farms. This may well suggest that respiration and metabolic of nematode communities was high and their impact on oxygen dissolved in surface water. Keywords Biomass, dissolved oxygen, Ca Mau, nematode communities, organic shrimp farms, oxgen demand References [1]. P. N. Hong, H. T. San, Mangroves of Vietnam 7 (1993) IUCN.[2]. T. Nga, Hệ thống rừng-tôm trong phát triển bền vững vùng ven biển đồng bằng sông Cửu Long. Tạp chí Khoa học Trường Đại học Cần Thơ 10 (2008) 6.[3]. Thai agricutural standard (TAS), Organic marine shrimp farming, Royal Gazette 124 (2007) Section 78E.[4]. T. T. Thai, N. T. My Yen, N. Tho, N. X. Quang, Meiofauna in the mangrove–shrimp farms ponds, Ca Mau province. Journal of Science and Technology 55(2017) 271.[5]. L. Marte, The Food and Feeding Habit of Penaeus Monodon Fabricius Collected From Makato River, Aklan, Philippines (Decapoda Natantia) 1, Crustaceana 38(1980) 225.[6]. N. Majdi, W. Traunspurger, Free-living nematodes in the freshwater food web: a review, Journal of nematology 47 (2015) 28.[7]. M. C. 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Pictorial key to world genera and notes for the identification of British species. Cambridge University Press, for the Linnean Society of London and the Estuarine and Brackish-water Sciences Association 1983.[17]. Andrassy I The determination of volume and weight of nematodes, Acta Zoologica 2 (1956) 1.[18]. J. Vanaverbeke, P. M. Arbizu, H. U. Dahms, H. K. Schminke,. The metazoan meiobenthos along a depth gradient in the Arctic Laptev Sea with special attention to nematode communities, Polar Biology 18 (1997) 391.[19]. K. Soetaert, J. Vanaverbeke, C. Heip, P. M. Herman, J. J. Middelburg, A. Sandee, G. Duineveld, Nematode distribution in ocean margin sediments of the Goban Spur (northeast Atlantic) in relation to sediment geochemistry, Deep Sea Research Part I: Oceanographic Research Papers, 44 (1997) 1671.[20]. D.J. Crisp Methods of the study of marine benthos (N.A. Holme & A.D. McIntyre eds), Blackwell Scientific Publications, Oxford, 1971 197. [21]. N. Smol, K. A. Willems, J. C. 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