Search Publications
Sensitivity of spectral lines to temperature, velocity, and magnetic field
Bellot Rubio, L. R.; del Toro Iniesta, J. C.; Cabrera Solana, D.
We present an analytical and numerical study of the sensitivity of weak solar photospheric lines to temperature, velocity, and magnetic fields. Our investigation is based on the concept of response functions (Landi degl'Innocenti & Landi degl'Innocenti 1977; Ruiz Cobo & del Toro Iniesta 1994). Lines commonly used in solar spectropolarimetr…
Asphericity and clumpiness in the winds of Luminous Blue Variables
Vink, Jorick S.; Davies, Ben; Oudmaijer, René D.
We present the first systematic spectropolarimetric study of Luminous Blue Variables (LBVs) in the Galaxy and the Magellanic Clouds, in order to investigate the geometries of their winds. We find that at least half of our sample show changes in polarization across the strong Hα emission line, indicating that the light from the stars is intrinsical…
The Ne/O abundance ratio in the quiet Sun
Young, P. R.
Context: .
Aims: .To determine the neon-to-oxygen abundance in the quiet Sun, a proxy for the photospheric abundance ratio.
Methods: .An emission measure method applied to extreme ultraviolet emission lines of Ne iv-vi and O iii-v ions observed by the Coronal Diagnostic Spectrometer on the SOHO satellite.
Results: .The average Ne/O abu…
INTEGRAL spectroscopy of the accreting millisecond pulsar XTE J1807-294 in outburst
Goldoni, P.; Bonnet-Bidaud, J. M.; Kuiper, L. +6 more
The transient X-ray accreting millisecond pulsar XTE J1807-294 was observed during its February/March 2003 outburst by INTEGRAL, partly simultaneously with the XMM-Newton and RXTE satellites. We present here the first study of the 0.5-200 keV broad-band spectra of the source. On February 28, the source spectrum was consistent with thermal Comptoni…
Characterizing a new class of variability in GRS 1915+105 with simultaneous INTEGRAL/RXTE observations
Belloni, T.; Rodriguez, J.; Mirabel, I. F. +14 more
We report on the analysis of 100 ks INTEGRAL observations of the Galactic microquasar
Initiation of hot coronal loop oscillations: Spectral features
Solanki, S. K.; Curdt, W.; Innes, D. E. +1 more
We explore the excitation of hot loop oscillations observed with the SUMER spectrograph on SOHO by analysing Fe XIX and Fe XXI spectral line profiles in the initial phase of the events. We investigate all 54 Doppler shift oscillations in 27 flare-like events, whose physical parameters have been measured so far. In nearly 50% of the cases, the spec…
Kinetic vs. multi-fluid models of H atoms in the heliospheric interface: a comparison
Izmodenov, V.; Alexashov, D.
The goal of this paper is to illuminate similarities and differences in the kinetic and multi-fluid models of the heliospheric interface, the region of solar wind interaction with the Local Interstellar Cloud (LIC), and then to explore physical reasons for these differences. We present a detailed comparison of two types of models. The first type i…
Relationship between X-ray and ultraviolet emission of flares from dMe stars observed by XMM-Newton
Raassen, A. J. J.; Mewe, R.; Audard, M. +6 more
We present simultaneous ultraviolet and X-ray observations of the dMe-type flaring stars
XMM-Newton observations of three poor clusters: Similarity in dark matter and entropy profiles down to low mass
Arnaud, M.; Pratt, G. W.
We present an analysis of the mass and entropy profiles of three poor galaxy clusters (A1991, A2717 and MKW9) observed with XMM-Newton. The clusters have very similar temperatures (kT= 2.65, 2.53 and 2.58 keV), and similar redshifts (0.04 ⪉ z ⪉ 0.06). We trace the surface brightness, temperature, entropy and integrated mass profiles with excellent…
X-ray absorption lines suggest matter infalling onto the central black-hole of Mrk 509
de Rosa, A.; Cappi, M.; Ponti, G. +2 more
Evidence for both red- and blue-shifted absorption lines due to ionized Fe in the X-ray spectrum of the Seyfert 1 galaxy Mrk 509 is reported. These features appear to be transient on time-scales as short as ~20 ks, and have been observed with two different satellites, BeppoSAX and XMM-Newton. The red- and blue-shifted lines are found at E∼5.5 keV …