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Scattering of emission lines in galaxy cluster cores: measuring electron temperature
Sunyaev, R.; Sazonov, S.; Churazov, E. +2 more
The central galaxies of some clusters can be strong emitters in the Lyα and Hα lines. This emission may arise either from the cool/warm gas located in the cool core of the cluster or from the bright AGN within the central galaxy. The luminosities of such lines can be as high as 1042-1044 erg s-1. This emission orig…
Analysing weak orbital signals in Gaia data
Lucy, L. B.
Anomalous orbits are found when minimum-χ2 estimation is applied to synthetic Gaia data for orbits with astrometric signatures comparable to the single-scan measurement error (Pourbaix 2002, A&A, 385, 686). These orbits are nearly parabolic, edge-on, and their major axes align with the line-of-sight to the observer. Such orbits viol…
The Evolution of the Net Twist Current and the Net Shear Current in Active Region NOAA 10930
Venkatakrishnan, P.; Ravindra, B.; Jaaffrey, S. N. A. +1 more
The electric current exists because of the non-potential magnetic field in solar active regions. We present the evolution of net current in the solar active region NOAA 10930 as the sum of shear current and twist current by using 27 high-resolution vector magnetograms obtained with Hinode/SOT-SP during 9 - 15 December 2006. This active region was …
Discussing the physical meaning of the absorption feature at 2.1 keV in 4U 1538-52
Torrejón, J. M.; Rodes-Roca, J. J.; Martínez-Nuñez, S. +2 more
High resolution X-ray spectroscopy is a powerful tool for studying the nature of the matter surrounding the neutron star in X-ray binaries and its interaction between the stellar wind and the compact object. In particular, absorption features in their spectra could reveal the presence of atmospheres of the neutron star or their magnetic field stre…
Variation in the statistical properties of IMF direction fluctuations during the 22-year solar magnetic cycle
Erofeev, D. V.
The variation in the IMF direction distribution during the 22-year solar magnetic cycle has been studied. Data obtained in near-Earth orbits and measurements in the heliospheric regions located far from the Earth, performed with the Helios and Ulysses spacecraft devices, have been analyzed. It has been found that the correlation between the azimut…
Inverse Compton origin of pulsar γ-ray emission and the reconnection model of Crab Nebula flares
Lyutikov, M.
There is growing evidence that the pulsar high-energy emission is generated by the inverse Compton effect. The particles producing the Crab nebula flares, and possibly most of the Crab Nebula's high-energy emission, are accelerated by reconnection events, and not by a shock according to the Fermi mechanism.
Improving LSST Photometric Calibration with Gaia Data
Axelrod, Tim; Miller, Calder
We consider the possibility that the Gaia mission can supply data which will improve the photometric calibration of LSST. After outlining the LSST calibra- tion process and the information that will be available from Gaia, we explore two options for using Gaia data. The first is to use Gaia G-band photometry of selected stars, in conjunction with …
Ultraviolet spectral variations of FK Comae and V 1794 Cygni
Sanad, M. R.; Bobrowsky, M.
Ultraviolet spectra of FK Comae and V1794 Cygni observed with the Hubble Space Telescope Cosmic Origins Spectrograph (HST COS) and the International Ultraviolet Explorer (IUE) satellites were analyzed for the period 1981-2011. Temporal variations of line fluxes of the O I 1306 Å, C II 1336 Å, C IV 1550 Å, He II 1640 Å and Mg II k & h 2800 Å, p…
A Dynamic Dark Information Energy Consistent with Planck Data
Gough, Michael Paul
The 2013 cosmology results from the European Space Agency Planck spacecraft provide new limits to the dark energy equation of state parameter. Here we show that Holographic Dark Information Energy (HDIE), a dynamic dark energy model, achieves an optimal fit to the published datasets where Planck data is combined with other astrophysical measuremen…
The Late Gradual Phase of Large Flares: The Case of November 3, 2003
Auraß, H.
The hard X-ray time profiles of most solar eruptive events begin with an impulsive phase that may be followed by a late gradual phase. In a recent article (Aurass et al. in Astron. Astrophys.555, A40, 2013), we analyzed the impulsive phase of the solar eruptive event on November 3, 2003 in radio and X-ray emission. We found evidence of magnetic br…