Search Publications
Disk Reflection Signatures in the Spectrum of the Bright Z-Source GX 340+0
Robba, N. R.; Di Salvo, T.; D'Aì, A. +2 more
We present the preliminary results of a 50 ks long XMM-Newton observation of the bright Z-source GX 340+0. In this Letter, we focus on the study of a broad asymmetric emission line in the Fe Kα energy band, whose shape is clearly resolved and compatible with a relativistically smeared profile arising from reflection on a hot accretion disk extendi…
On the Propagation of p-Modes Into the Solar Chromosphere
De Pontieu, B.; McIntosh, S. W.; de Wijn, A. G.
We employ tomographic observations of a small region of plage to study the propagation of waves from the solar photosphere to the chromosphere using a Fourier phase-difference analysis. Our results show the expected vertical propagation for waves with periods of 3 minutes. Waves with 5 minute periods, i.e., above the acoustic cutoff period, are fo…
Hot Plasma in Nonflaring Active Regions Observed by the Extreme-Ultraviolet Imaging Spectrometer on Hinode
Warren, Harry P.; Doschek, George A.; Young, Peter R. +1 more
The Extreme-Ultraviolet Imaging Spectrometer (EIS) on the Hinode spacecraft obtains high-resolution spectra of the solar atmosphere in two wavelength ranges: 170-210 and 250-290 Å. These wavelength regions contain a wealth of emission lines covering temperature regions from the chromosphere/transition region (e.g., He II, Si VII) up to flare tempe…
Comprehensive Observations of a Solar Minimum Coronal Mass Ejection with the Solar Terrestrial Relations Observatory
Plunkett, S. P.; Howard, R. A.; Wood, B. E. +1 more
We perform the first kinematic analysis of a coronal mass ejection (CME) observed by both imaging and in situ instruments on board the Solar Terrestrial Relations Observatory (STEREO). Launched on 2008 February 4, the CME is tracked continuously from initiation to 1 AU using the imagers on both STEREO spacecraft, and is then detected by the partic…
Three-dimensional Radiative Transfer Modeling of the Polarization of the Sun's Continuous Spectrum
Shchukina, Nataliya; Trujillo Bueno, Javier
Polarized light provides the most reliable source of information at our disposal for diagnosing the physical properties of astrophysical plasmas, including the three-dimensional (3D) structure of the solar atmosphere. Here we formulate and solve the 3D radiative transfer problem of the linear polarization of the solar continuous radiation, which i…
Spectroscopic Observations of Hot Lines Constraining Coronal Heating in Solar Active Regions
Klimchuk, J. A.; Patsourakos, S.
Extreme-ultraviolet observations of warm coronal loops suggest that they are bundles of unresolved strands that are heated impulsively to high temperatures by nanoflares. The plasma would then have the observed properties (e.g., excess density compared with static equilibrium) when it cools into the 1-2MK range. If this interpretation is correct, …
Coronal Nonthermal Velocity Following Helicity Injection Before an X-Class Flare
Tsuneta, S.; Doschek, G. A.; Hara, H. +5 more
We explore the "pre-flare" behavior of the corona in a three-day period building up to an X-class flare on 2006 December 13 by analyzing EUV spectral profiles from the Hinode EUV Imaging Spectrometer (EIS) instrument. We found an increase in the coronal spectral line widths, beginning after the time of saturation of the injected helicity as measur…
Properties of the Diffuse X-ray Background toward MBM20 with Suzaku
Smith, R.; Gupta, A.; Lallement, R. +2 more
We used Suzaku observations of the molecular cloud MBM20 and a low neutral hydrogen column density region nearby to separate and characterize the foreground and background diffuse X-ray emission. A comparison with a previous observation of the same regions with XMM-Newton indicates a significant change in the foreground flux which is attributed to…
Stellar Masses of Lyman Break Galaxies, Lyα Emitters, and Radio Galaxies in Overdense Regions at z = 4-6
White, Richard L.; Illingworth, Garth D.; Bouwens, Rychard J. +8 more
We present new information on galaxies in the vicinity of luminous radio galaxies (RGs) and quasars at zsime4, 5, and 6. These fields were previously found to contain overdensities of Lyman Break Galaxies (LBGs) or spectroscopic Lyα emitters, which were interpreted as evidence for clusters-in-formation ("protoclusters"). We use Hubble Space Telesc…
Observations of X-Ray Oscillations in ξ Boo: Evidence of a Fast-Kink Mode in the Stellar Loops
Srivastava, A. K.; Pandey, J. C.
We report the observations of X-ray oscillations during the flare in a cool active star ξ Boo for the first time. ξ Boo was observed by EPIC/MOS of the XMM-Newton satellite. The X-ray light curve is investigated with wavelet and periodogram analyses. Both analyses clearly show oscillations of the period of ~1019 s. We interpret these oscillations …