32 research outputs found

    Level of biogenic and organic substances in a water of the Dniprovs’ke reservoir and Samara River in fall-winter period

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    Вивчено актуальні проблеми впливу евтрофування Дніпровського водосховища органічними та біогенними речовинами господарсько-побутових і промислових стічних вод на рибогосподарські показники. Проведені досліди показали перевищення ГДК за деякими показниками для рибогосподарських водойм.Вивчено актуальні проблеми впливу евтрофування Дніпровського водосховища органічними та біогенними речовинами господарсько-побутових і промислових стічних вод на рибогосподарські показники. Проведені досліди показали перевищення ГДК за деякими показниками для рибогосподарських водойм.Relevant problems of influence of the Dniprovs’ke reservoir eutrophication by the household sewage on the water quality indices in fishing zones were studied. Investigations disclosed the excess of the maximum permissible concentration of some indices developed for a fishing reservoir

    Observations of PSR J2021+3651 and its X-ray Pulsar Wind Nebula G75.2+0.1

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    We present results from X-ray and radio observations of the recently discovered young Vela-like pulsar PSR J2021+3651, which is coincident with the EGRET gamma-ray source GeV 2020+3658. A 19.0-ks Chandra ACIS-S observation has revealed a ~20'' x 10'' pulsar wind nebula that is reminiscent of the equatorial tori seen around some young pulsars, along with thermal emission from an embedded point source (kT = 0.15 +/- 0.02 keV). We name the nebula G75.2+0.1. Its spectrum is well fit by an absorbed power-law model with photon index 1.7 +/- 0.3, hydrogen column density nH = 7.8 +/- 1.7 x 10^21 cm^-2, and an unabsorbed 0.3-10.0 keV flux of 1.9 +/- 0.3 x 10^-12 erg cm^-2 s^-1. We have spatially fit G75.2+0.1 with a model that assumes a toroidal morphology, and from this we infer that the torus is highly inclined 83 deg +/- 1 deg to the line of sight. A 20.8-ks Chandra observation in continuous-clocking mode reveals a possible pulse detection, with a pulsed fraction of ~37% and an H-test probability of occuring by chance of 1.2 x 10^-4. Timing observations with the Arecibo radio telescope spanning two years show that PSR J2021+3651 glitched sometime between MJDs 52616 and 52645 with parameters delta(v)/v = (2.587 +/- 0.002) x 10^-6 and delta(dot(v))/v = (6.2 +/- 0.3) x 10^-3, similar to those of the largest glitches observed in the Vela pulsar. PSR J2021+3651 is heavily scattered (T_sc = 17.7 ms +/- 0.9 ms at 1 GHz) and exhibits a significant amount of timing noise.Comment: 23 pages, 6 figures. Submitted to the Astrophysical Journa

    The Effective Temperature Scale of Galactic Red Supergiants: Cool, But Not As Cool As We Thought

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    We use moderate-resolution optical spectrophotometry and the new MARCS stellar atmosphere models to determine the effective temperatures of 74 Galactic red supergiants. From these we find a new effective temperature scale that is significantly warmer than those in the literature. We show that this temperature scale, along with the newly derived bolometric corrections, gives much better agreement between our red supergiants and stellar evolutionary tracks. This agreement provides an independent verification of our new temperature scale. The combination of effective temperature and bolometric luminosities allows us to calculate stellar radii; the coolest and most luminous stars have radii of roughly 1500 solar radii (7 AU), in excellent accordance with the largest stellar radii predicted from current evolutionary theory. We find that similar results are obtained for the effective temperatures and bolometric luminosities using only the de-reddened V-K colors, providing a powerful demonstration of the self-consistency of the MARCS models.Comment: 32 pages, 16 figures; Accepted by the Astrophysical Journa

    Galactic Kinematics from OB3 Stars with Distances determined from Interstellar Ca II Lines

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    Based on data for 102 OB3 stars with known proper motions and radial velocities, we have tested the distances derived by Megier et al. from interstellar Ca II spectral lines. The internal reconciliation of the distance scales using the first derivative of the angular velocity of Galactic rotation {\Omega}'0 and the external reconciliation with Humphreys's distance scale for OB associations refined by Mel'nik and Dambis show that the initial distances should be reduced by \approx 20%. Given this correction, the heliocentric distances of these stars lie within the range 0.6-2.6 kpc. A kinematic analysis of these stars at a fixed Galactocentric distance of the Sun, R0=8 kpc, has allowed the following parameters to be determined:(1) the solar peculiar velocity components (U_o,V_o,W_o)=(8.9,10.3,6.8)\pm(0.6,1.0,0.4) km/s;(2) the Galactic rotation parameters {\Omega}_o=-31.5\pm0.9 km/s/kpc, {\Omega}'_o=+4.49\pm0.12 km/s/kpc^2, {\Omega}"_o=-1.05\pm0.38 km/s/kpc^3, (the corresponding Oort constants are A=17.9\pm0.5 km/s/kpc, B=-13.6\pm1.0 km/s/kpc and the circular rotation velocity of the solar neighborhood is |V_o|=252\pm14 km/s); (3) the spiral density wave parameters, namely: the perturbation amplitudes for the radial and azimuthal velocity components, respectively, f_R = -12.5\pm1.1 km/s and f_{\theta}=2.0\pm1.6 km/s; the pitch angle for the two-armed spiral pattern i=-5.3\pm0.3 degrees, with the wavelength of the spiral density wave at the solar distance being {\lambda}=2.3\pm0.2 kpc; the Sun's phase in the spiral wave {\chi}_o=-91\pm4 degrees.Comment: 14 pages, 4 figures, 3 table

    CMS physics technical design report : Addendum on high density QCD with heavy ions

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