Search Publications
TC-1 observations of flux pileup and dipolarization-associated expansion in the near-Earth magnetotail during substorms
Escoubet, C. P.; Dandouras, I.; Zhang, H. +16 more
Fifty-three substorms measured by Double Star/TC-1 in the near-Earth magnetotail from July to October, 2004 are studied. The main features of these events are: (a) Magnetic flux pileup characterized by continuous enhancement of B z is observed, which starts almost simultaneously with aurora breakup within 1-3 minutes, indicating that …
Helioseismic Holography of Simulated Solar Convection and Prospects for the Detection of Small-Scale Subsurface Flows
Birch, A. C.; Braun, D. C.; Nordlund, Å. +2 more
We perform helioseismic holography on realistic solar convection simulations and compare the observed travel-time perturbations with the expected travel times from the horizontal flows in the simulations computed from forward models under the assumption of the Born approximation. We demonstrate reasonable agreement between the observed and model t…
The XMM-Newton view of IRAS 09104+4109: evidence for a changing-look Type 2 quasar?
Fiore, F.; Piconcelli, E.; Comastri, A. +4 more
Aims:We report on a 14 ks XMM-Newton observation of the hyperluminous infrared galaxy IRAS 09104+4109, which harbors a type 2 quasar in its nucleus. Our analysis was aimed at studying the properties of the absorbing matter and the Fe K complex at 6-7 keV in this source.
Methods: We analyzed the spectroscopic data from the PN and the MOS camera…
Hinode Observations of the Onset Stage of a Solar Filament Eruption
Narukage, Noriyuki; Kano, Ryohei; Sakao, Taro +12 more
We used Hinode X-Ray Telescope (XRT) and Solar Optical Telescope (SOT) filtergraph (FG) Stokes-V magnetogram observations, to study the early onset of a solar eruption that includes an erupting filament that we observe in TRACE EUV images. The filament undergoes a slow rise for at least 20min prior to its fast eruption and strong soft X-ray (SXR) …
Chandra Observations of Candidate ``True'' Seyfert 2 Nuclei
Shields, Joseph C.; Pogge, Richard W.; Mathur, Smita +2 more
The unification model for AGNs posits that Seyfert 2 galaxies are intrinsically like Seyfert 1 galaxies, but that their broad-line regions (BLRs) are hidden from our view. A Seyfert 2 nucleus that truly lacked a BLR, instead of simply having it hidden, would be a so-called true Seyfert 2. No object has as yet been conclusively proven to be one. We…
Simultaneous INTEGRAL and RXTE observations of the accreting millisecond pulsar HETE J1900.1-2455
Stella, L.; Bonnet-Bidaud, J. M.; Kuiper, L. +5 more
Aims:HETE J1900.1-2455 is the seventh known X-ray transient accreting millisecond pulsar and has been in outburst for more than one year. We compared the data on HETE J1900.1-2455 with other similar objects and made an attempt at deriving constraints on the physical processes responsible for a spectral formation.
Methods: The broad-band spectr…
Observational signatures of the interaction between acoustic waves and the solar magnetic canopy
McIntosh, S. W.; Jefferies, S. M.; Armstrong, J. D. +1 more
Aims:We show that the spatial distribution (and its variation with frequency) of the power spectra of the velocity and intensity signals, in and around solar active regions, is a manifestation of the interaction of acoustic waves at the magnetic canopy.
Methods: We analysed 6 h of simultaneous, full-disk, velocity and intensity images obtained…
Suzaku Spectroscopic Study of Hard X-Ray Emission in the Arches Cluster
Tsujimoto, Masahiro; Koyama, Katsuji; Hyodo, Yoshiaki
We present the results of a Suzaku study of the Arches cluster in the Galactic center region. A high signal-to-noise ratio spectrum in the 3-12keV band was obtained with the X-ray Imaging Spectrometer (XIS) onboard the Suzaku observatory. We found that the spectrum consists of a thermal plasma, a hard power-law tail, and two Gaussian line componen…
Interaction between coronal mass ejections and the solar wind
Breen, A. R.; Bisi, M. M.; Fallows, R. A. +3 more
Observations suggest that the interplanetary extensions of coronal mass ejections (iCMEs) may be accelerated or decelerated in their passage through the solar wind. Interplanetary scintillation measurements (IPS) can detect the passage of iCMEs beyond the field of view of the Large-Angle and Spectrometric Coronagraph coronagraphs and can provide i…
A refined analysis of the remarkable Bp star HR 6000
Hubrig, S.; Castelli, F.
Aims:UVES spectra of the very young (∼ 107 years) peculiar B-type star HR 6000 were analyzed in the near-UV and visual spectral regions (3050-9460 Å) with the aim of extending to other spectral ranges the study made previously in the UV using IUE spectra.
Methods: Stellar parameters T_eff = 12 850 K, log g = 4.10, and ξ=0 km s-…