7,121 research outputs found

    The 'equilibrium' anisotropy in the flux of 10 MeV solar flare particles and their convection in the solar wind

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    Equilibrium anisotropy in flux solar flare particles calculated from particle spectra and solar wind speed

    Tool pre-tensions covers prior to lacing

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    In securing a bulky object in a storage compartment, a cinching or tightening tool is used to draw two opposing cover halves together at a predetermined tension to permit quick lacing to retain the stored object. This tool is also useful in fabrication industries to draw components together during assembly or treating

    Particle acceleration in solar flares

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    The most direct signatures of particle acceleration in flares are energetic particles detected in interplanetary space and in the Earth atmosphere, and gamma rays, neutrons, hard X-rays, and radio emissions produced by the energetic particles in the solar atmosphere. The stochastic and shock acceleration theories in flares are reviewed and the implications of observations on particle energy spectra, particle confinement and escape, multiple acceleration phases, particle anistropies, and solar atmospheric abundances are discussed

    Detection of ocean color changes from high altitudes

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    The detection of ocean color changes, thought to be due to chlorophyll concentrations and gelbstoffe variations, is attempted from high altitude (11.3km) and low altitude (0.3km). The atmospheric back scattering is shown to reduce contrast, but not sufficiently to obscure color change detection at high altitudes

    Propagation of the phase of solar modulation

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    The phase of the 11 year galactic cosmic ray variation, due to a varying rate of emission of long lived propagating regions of enhanced scattering, travels faster than the scattering regions themselves. The radial speed of the 11 year phase in the quasi-steady, force field approximation is exactly twice the speed of the individual, episodic decreases. A time dependent, numerical solution for 1 GeV protons at 1 and 30 Au gives a phase speed which is 1.85 times the propagation speed of the individual decreases

    ESO 3060170 -- a massive fossil galaxy group with a heated gas core?

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    We present a detailed study of the ESO 3060170 galaxy group combining Chandra, XMM and optical observations. The system is found to be a fossil galaxy group. The group X-ray emission is composed of a central dense cool core (10 kpc in radius) and an isothermal medium beyond the central 10 kpc. The region between 10 and 50 kpc (the cooling radius) has the same temperature as the gas from 50 kpc to 400 kpc although the gas cooling time between 10 and 50 kpc (2 - 6 Gyr) is shorter than the Hubble time. Thus, the ESO 3060170 group does not have a group-sized cooling core. We suggest that the group cooling core may have been heated by a central AGN outburst in the past and the small dense cool core is the truncated relic of a previous cooling core. The Chandra observations also reveal a variety of X-ray features in the central region, including a ``finger'', an edge-like feature and a small ``tail'', all aligned along a north-south axis, as are the galaxy light and group galaxy distribution. The proposed AGN outburst may cause gas ``sloshing'' around the center and produce these asymmetric features. The observed flat temperature profile to 1/3 R_vir is not consistent with the predicted temperature profile in recent numerical simulations. We compare the entropy profile of the ESO 3060170 group with those of three other groups and find a flatter relation than that predicted by simulations involving only shock heating, S \propto r 0.85^{~ 0.85}. This is direct evidence for the importance of non-gravitational processes in group centers. We derive the mass profiles within 1/3 R_vir and find the ESO 3060170 group is the most massive fossil group known (1 - 2 X 1014^{14} M_{\odot}). The M/L ratio of the system, ~ 150 at 0.3 R_vir, is normal.Comment: 17 pages, 12 figures, to appear in ApJ. A high-resolution version can be downloaded from http://cxc.harvard.edu/~msun/esoa.p

    CHANDRA observations of the NGC 1550 galaxy group -- implication for the temperature and entropy profiles of 1 keV galaxy groups

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    We present a detailed \chandra study of the galaxy group NGC 1550. For its temperature (1.37±\pm0.01 keV) and velocity dispersion (\sim 300 km s1^{-1}), the NGC 1550 group is one of the most luminous known galaxy groups (Lbol_{\rm bol} = 1.65×1043\times10^{43} erg s1^{-1} within 200 kpc, or 0.2 \rv). We find that within 60\sim 60 kpc, where the gas cooling time is less than a Hubble time, the gas temperature decreases continuously toward the center, implying the existence of a cooling core. The temperature also declines beyond \sim 100 kpc (or 0.1 \rv). There is a remarkable similarity of the temperature profile of NGC 1550 with those of two other 1 keV groups with accurate temperature determination. The temperature begins to decline at 0.07 - 0.1 \rv, while in hot clusters the decline begins at or beyond 0.2 \rv. Thus, there are at least some 1 keV groups that have significantly different temperature profiles from those of hot clusters, which may reflect the role of non-gravitational processes in ICM/IGM evolution. NGC 1550 has no isentropic core in its entropy profile, in contrast to the predictions of `entropy-floor' simulations. We compare the scaled entropy profiles of three 1 keV groups (including NGC 1550) and three 2 - 3 keV groups. The scaled entropy profiles of 1 keV groups show much larger scatter than those of hotter systems, which implies varied pre-heating levels. We also discuss the mass content of the NGC 1550 group and the abundance profile of heavy elements.Comment: emulateapj5.sty, 18 pages, 11 figures (including 4 color), to appear in ApJ, v598, n1, 20 Nov 200
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