Search Publications
Zeeman-tomography of the solar photosphere. Three-dimensional surface structures retrieved from Hinode observations
Carroll, T. A.; Kopf, M.
Aims:The thermodynamic and magnetic field structure of the solar photosphere is analyzed by means of a novel 3-dimensional spectropolarimetric inversion and reconstruction technique.
Methods: On the basis of high-resolution, mixed-polarity magnetoconvection simulations, we used an artificial neural network (ANN) model to approximate the nonlin…
Reflection-dominated X-ray spectra of narrow-line Seyfert 1 galaxies: Mrk 478 and EXO 1346.2+2645
Fabian, A. C.; Gallo, L. C.; Zoghbi, A.
Multi-epoch XMM-Newton spectra of the two narrow-line Seyfert 1 (NLS1), Mrk 478 and EXO 1346.2+2645, are presented. The data were fitted with different models, including the relativistically blurred reflection model REFLIONX, which was found to give a good description of both spectra in all epochs. The two sources are reflection dominated with the…
A Search for Synchrotron X-Ray Emission in Radio Quasars
Giommi, Paolo; Cheung, Chi C.; Landt, Hermine +2 more
This paper presents XMM-Newton and Chandra X-ray spectroscopy of 10 flat-spectrum radio quasars (FSRQ) that are candidates to have an X-ray spectrum dominated by jet synchrotron emission. In all these FSRQ, which are less strongly relativistically beamed than blazars, a considerable contribution from a power-law component similar to that present i…
On the combination of ACE data with numerical simulations to determine the initial characteristics of a CME
Poedts, S.; Chané, E.; van der Holst, B.
Aims: Our goal is to combine the Advanced Composition Explorer (ACE) data with numerical simulations to determine the initial characteristics of the halo coronal mass ejection (CME), which was observed on April 4, 2000.
Methods: The evolution of a CME from the Sun to 1 AU is simulated in the framework of 2.5 D (axi-symmetric) ideal Magnetohydr…
PKS2250-41: a case study for triggering
Villar-Martín, M.; Morganti, R.; Tadhunter, C. N. +3 more
We present the results of a multiwavelength study of the z = 0.31 radio source PKS2250-41. Integral field unit and long-slit spectroscopy obtained using VIMOS and FORS1 on the VLT, and archival Hubble Space Telescope optical imaging observations are used to study the morphology, kinematics and ionization state of the extended emission-line region …
X-Ray Observations of the Coma Cluster in a Broad Energy Band with the INTEGRAL, RXTE, and ROSAT Observatories
Sunyaev, R. A.; Vikhlinin, A.; Lutovinov, A. A. +2 more
We present results of X-ray observations of the Coma Cluster with multiple instruments over a broad energy band. Using the data from the INTEGRAL, RXTE, and ROSAT observatories, we find that the Coma spectrum in the 0.5-107 keV energy band can be well approximated by a thermal plasma emission model with a temperature of T = 8.2 keV. INTEGRAL was u…
Intensity oscillations and heating of the coronal X-ray bright points from Hinode/XRT
Kariyappa, R.; Varghese, B. A.
Aims: Our aim is to investigate the intensity oscillations in coronal X-ray Bright Points (XBPs).
Methods: We analysed a 7 h long time sequence of the soft X-ray images obtained on April 14, 2007 with a 2 min cadence using the X-Ray Telescope (XRT) on-board the Hinode mission. We use SSW in IDL to derive the time series of 14 XBPs and 2 backgr…
Preliminary orbital elements of six visual binary stars
Scardia, M.; Prieur, J. -L.; Pansecchi, L. +1 more
Preliminary new orbital elements were computed for the visual binary stars A 1 - ADS 1345, A 2629 - ADS 3610, BU 560 - ADS 4371, STF 3115 - ADS 4376, STF 1426 AB - ADS 7730 and STF 2437 - ADS 11956. Using Straizys and Kuriliene's data, we derived new formulae for computing dynamical parallaxes for luminosity classes IV and V. The values found for …
The Evolution of Late-Time Optical Emission from SN 1986J
Kirshner, Robert P.; Leibundgut, Bruno; Milisavljevic, Dan +1 more
We present late-time optical images and spectra of the Type IIn supernova SN 1986J. HST ACS/WFC images obtained in 2003 February show it to be still relatively bright, with mF606W = 21.4 and mF814W = 20.0 mag. Compared to 1994 December HST WFPC2 images, SN 1986J shows a decline of only lesssim1 mag in brightness over 8 years.…
Magnetic complexity in eruptive solar active regions and associated eruption parameters
Georgoulis, Manolis K.
Using an efficient magnetic complexity index in the active-region solar photosphere, we quantify the preflare strength of the photospheric magnetic polarity inversion lines in 23 eruptive active regions with flare/CME/ICME events tracked all the way from the Sun to the Earth. We find that active regions with more intense polarity inversion lines h…