Search Publications
XMM-Newton Observations of the Seyfert 2 Galaxy NGC 7590: The Nature of X-ray Absorption
Shu, X. W.; Wang, J. X.; Liu, T.
We present the analysis of three XMM-Newton observations of the Seyfert 2 galaxy NGC 7590. The source was found to have no X-ray absorption in the low spatial resolution ASCA data. The XMM-Newton observations provide a factor of ~10 better spatial resolution than previous ASCA data. We find that the X-ray emission of NGC 7590 is dominated by an of…
High- and low-resolution spectroscopic observations of the peculiar planetary-nebula HD 149427 (=PC 11)
Pereira, C. B.; Miranda, L. F.; Daflon, S. +1 more
Aims: We discuss the status of the A-type component of the binary central star in the peculiar planetary nebula HD 149427.
Methods: We acquired low and high spectral resolution optical spectroscopy for the range 4500-9000 Å.
Results: The analysis of the high resolution spectrum shows that the A-type star has an effective temperature…
Evidence for subaqueously resedimented sulphate evaporites on Mars
Baioni, Davide; Wezel, Forese Carlo
This article documents the clastic nature of sulphate evaporite beds in the Tithonium Chasma located in the Valles Marineris region of Mars. These beds form a stratified succession characterised by very thick interbedded channel-fill breccia bodies. We infer that the bouldery channel-fills were deposited by voluminous mass-flow processes occurring…
Global configuration of Saturn's magnetic field derived from observations
Dougherty, M. K.; Khurana, K. K.; Carbary, J. F. +2 more
Magnetic field observations from the Cassini spacecraft are averaged into 1 × 1 RS (1 RS = 60238 km) meridional bins at Saturn. A Runge-Kutta procedure uses the bin-averaged field components to estimate the global configuration of Saturn's magnetic field and map field lines from the equator to Saturn's ionosphere. Within ∼18 …
Formation and evolution of early-type galaxies: spectro-photometry from cosmo-chemo-dynamical simulations
Merlin, E.; Piovan, L.; Chiosi, C. +2 more
Context. One of the major challenges in modern astrophysics is to understand the origin and the evolution of galaxies, the bright, massive early type galaxies (ETGs) in particular. There is strong observational evidence that massive ETGs are already in place at redshift z ~ 2-3 and that they formed most of their stars well before z = 1. Therefore,…
Acoustic power absorption and enhancement generated by slow and fast MHD waves. Evidence of solar cycle velocity/intensity amplitude changes consistent with the mode conversion theory
García, R. A.; Finsterle, W.; Elsworth, Y. +4 more
We used long duration, high quality, unresolved (Sun-as-a star) observations collected by the ground based network BiSON and by the instruments GOLF and VIRGO on board the ESA/NASA SOHO satellite to search for solar-cycle-related changes in mode characteristics in velocity and continuum intensity for the frequency range between 2.5 mHz <ν< 6…
The AGN fraction of submm-selected galaxies and contributions to the submm/mm-wave extragalactic background light
Im, M.; Kim, S.; Farrah, D. +22 more
We present a comparison of the SCUBA half degree extragalactic survey (SHADES) at 450 µm, 850 µm and 1100 µm with deep guaranteed time 15 µm AKARI FU-HYU survey data and Spitzer guaranteed time data at 3.6-24 µm in the Lockman hole east. The AKARI data was analysed using bespoke software based in part on the drizzling…
Photocentric orbits from a direct combination of ground-based astrometry with Hipparcos II. Preliminary orbits for six astrometric binaries
Gontcharov, G. A.; Kiyaeva, O. V.
Based on a direct combination of the Hipparcos data with astrometric ground-based observational catalogues having epochs between 1938 and 1999 the preliminary orbits and component masses are calculated for six binaries with no previous orbit calculation: ι Vir (HIP 69701) with period of 55 years, photocentric semi-major axis of 200 mas, relative s…
Harmonic growth of ion-cyclotron waves in Saturn's magnetosphere
Russell, C. T.; Dougherty, M. K.; Wilson, R. J. +3 more
Ion-cyclotron waves have been observed by the Cassini spacecraft in Saturn's middle magnetosphere. Waves have frequencies near the gyrofrequencies of water-group ions, they are left handed, and in most regions they propagate at small angles to the ambient magnetic field. Their origin is explained in terms of the ion-cyclotron instability generated…
Trans-Equatorial Loop System Arising from Coronal Hole Boundaries through Interactions between Active Regions and Coronal Holes
Masuda, Satoshi; Yokoyama, Masaki
It is not clear how trans-equatorial loop systems (TLSs) are formed, although they have been observed often with Yohkoh/SXT. We focus here on a TLS that appeared on 27 May 1998. Yokoyama and Masuda (Solar Phys.254, 285, 2009) proposed a new scenario for the formation mechanism of the TLS. In this scenario, they pointed out the importance of magnet…