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Type I X-ray bursts, burst oscillations and kHz quasi-periodic oscillations in the neutron star system IGRJ17191-2821
Altamirano, D.; Degenaar, N.; Wijnands, R. +6 more
We present a detailed study of the X-ray energy and power spectral properties of the neutron star transient IGRJ17191-2821. We discovered four instances of pairs of simultaneous kilohertz quasi-periodic oscillations (kHz QPOs). The frequency difference between these kHz QPOs is between 315 and 362Hz. We also report on the detection of five thermon…
New measurement of orbital and spin period evolution of the accretion disc corona source 4U 1822-37
Paul, Biswajit; Jain, Chetana; Dutta, Anjan
4U 1822-37 is a low mass X-ray binary (LMXB) system with an accretion disc corona. It is one of the very few LMXBs that shows narrow X-ray eclipses and small amplitude pulsations of the neutron star. The X-ray eclipse is an excellent reference for measurement of orbital evolution of the binary, and we have obtained 16 new mid-eclipse time measurem…
Searching for stars closely encountering with the solar system
Bobylev, V. V.
Based on a new version of the Hipparcos catalog and currently available radial velocity data, we have searched for stars that either have encountered or will encounter the solar neighborhood within less than 3 pc in the time interval from -2 Myr to +2 Myr. Nine new candidates within 30 pc of the Sun have been found. To construct the stellar orbits…
The Herschel view of GAS in Protoplanetary Systems (GASPS). First comparisons with a large grid of models
Pinte, C.; Ménard, F.; Duchêne, G. +49 more
The Herschel GASPS key program is a survey of the gas phase of protoplanetary discs, targeting 240 objects which cover a large range of ages, spectral types, and disc properties. To interpret this large quantity of data and initiate self-consistent analyses of the gas and dust properties of protoplanetary discs, we have combined the capabilities o…
Luminous X-ray Active Galactic Nuclei in Clusters of Galaxies
Plionis, M.; Koulouridis, E.
We present a study of X-ray active galactic nucleus (AGN) overdensities in 16 Abell clusters, within the redshift range 0.073 < z < 0.279, in order to investigate the effect of the hot inter-cluster environment on the triggering of the AGN phenomenon. The X-ray AGN overdensities, with respect to the field expectations, were estimated for sou…
Response of the Solar Atmosphere to the Emergence of `Serpentine' Magnetic Field
Tsuneta, S.; Hara, H.; Harra, L. K. +3 more
Active region magnetic flux that emerges to the photosphere from below will show complexity in the structure, with many small-scale fragmented features appearing in between the main bipole and then disappearing. Some fragments seen will be absorbed into the main polarities and others seem to cancel with opposite magnetic field. In this paper we in…
Magnetic Energy Spectra in Solar Active Regions
Yurchyshyn, Vasyl; Abramenko, Valentyna
Line-of-sight magnetograms for 217 active regions (ARs) with different flare rates observed at the solar disk center from 1997 January until 2006 December are utilized to study the turbulence regime and its relationship to flare productivity. Data from the SOHO/MDI instrument recorded in the high-resolution mode and data from the BBSO magnetograph…
Minerals mapping of the lunar surface with Clementine UVVIS/NIR data based on spectra unmixing method and Hapke model
Wang, Zhenchao; Yan, Bokun; Gan, Fuping +1 more
The distribution of minerals on the lunar surface is information which could contribute to studying lunar origin and evolution. In this paper, the distribution of clinopyroxene, orthopyroxene, olivine, ilmenite, and plagioclase on the lunar surface has been mapped based on Hapke radiative transfer model and linear unmixing of spectra with Clementi…
The evolutionary status of the blue hook stars in ω Centauri
D'Antona, Francesca; Ventura, Paolo; Caloi, Vittoria
Core helium burning is the dominant source of energy of extreme horizontal branch stars, as the hydrogen envelope is too small to contribute to the nuclear energy output. The evolution of each mass in the HR diagram occurs along vertical tracks that, when the core helium is consumed, evolve to higher Teff and then to the white dwarf sta…
Evidence of supercritical disc funnel radiation in X-ray spectra of SS 433
Fabrika, S.; Medvedev, A.
We analysed the XMM-Newton spectra of SS433 using a standard model of adiabatically and radiatively cooling X-ray jets. The multitemperature thermal jet model reproduces the strongest observed emission line fluxes well. Fitting the He- and H-like iron line fluxes, we find that the visible blue jet base temperature is ~17 keV, the jet kinetic lumin…