Search Publications
Comparison of Hinode/XRT and RHESSI Detection of Hot Plasma in the Non-Flaring Solar Corona
Testa, Paola; Reale, Fabio; McTiernan, James M.
We compare observations of the non-flaring solar corona made simultaneously with Hinode/XRT and RHESSI. The analyzed corona is dominated by a single active region on 2006 November 12. The comparison is made on emission measures. We derive emission measure distributions versus temperature of the entire active region from multifilter XRT data. We ch…
Intrinsic Instability of Coronal Streamers
Feng, S. W.; Chen, Y.; Song, H. Q. +3 more
Plasma blobs are observed to be weak density enhancements as radially stretched structures emerging from the cusps of quiescent coronal streamers. In this paper, it is suggested that the formation of blobs is a consequence of an intrinsic instability of coronal streamers occurring at a very localized region around the cusp. The evolutionary proces…
Analytic Modeling of the Moreton Wave Kinematics
Temmer, M.; Veronig, A. M.; Vršnak, B. +1 more
The issue whether Moreton waves are flare-ignited or coronal mass ejection (CME)-driven, or a combination of both, is still a matter of debate. We develop an analytical model describing the evolution of a large-amplitude coronal wave emitted by the expansion of a circular source surface in order to mimic the evolution of a Moreton wave. The model …
Suzaku Observations of PSR B1259-63: A New Manifestation of Relativistic Pulsar Wind
Nakazawa, Kazuhiro; Takahashi, Tadayuki; Mori, Koji +2 more
We observed PSR B1259-63, a young nonaccreting pulsar orbiting around a Be star SS 2883, eight times with the Suzaku satellite from 2007 July to September, to characterize the X-ray emission arising from the interaction between a pulsar relativistic wind and Be star outflows. The X-ray spectra showed a featureless continuum in 0.6-10 keV, modeled …
Observations of the Thermal and Dynamic Evolution of a Solar Microflare
Brosius, Jeffrey W.; Holman, Gordon D.
We observed a solar microflare over a wide temperature range with three instruments aboard the SOHO spacecraft (Coronal Diagnostic Spectrometer (CDS), Extreme-ultraviolet Imaging Telescope (EIT), and Michelson Doppler Imager (MDI)), TRACE (1600 Å), GOES, and RHESSI. The microflare's properties and behavior are those of a miniature flare undergoing…
CHIANTI—An Atomic Database for Emission Lines. X. Spectral Atlas of a Cold Feature Observed with Hinode/EUV Imaging Spectrometer
Young, P. R.; Landi, E.
In this work, we report on a cold, bright portion of an active region observed by the Hinode/EUV Imaging Spectrometer. The emitting plasma was very bright at transition region temperatures, and the intensities of lines of ions formed between 105 and 106 K were enhanced over normal values. The data set constitutes an excellent…
Preferential Acceleration and Perpendicular Heating of Minor Ions in a Collisionless Coronal Hole
Isenberg, Philip A.; Vasquez, Bernard J.
We incorporate the cyclotron-resonant Fermi heating mechanism of Isenberg & Vasquez into an inhomogeneous, collisionless coronal hole model to investigate this kinetic process in the presence of the other known forces on the coronal hole minor ions. The model includes the effects of gravity, charge-separation electric field, and mirroring in t…
Barred Galaxies in the Abell 901/2 Supercluster with Stages
Bell, Eric F.; Wisotzki, Lutz; Wolf, Christian +22 more
We present a study of bar and host disk evolution in a dense cluster environment, based on a sample of ~800 bright (M V <= -18) galaxies in the Abell 901/2 supercluster at z~ 0.165. We use Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) F606W imaging from the STAGES survey, and data from Spitzer, XMM-Newton, and COMBO-…
The Cycles of α Centauri
Ayres, Thomas R.
The main AB pair of the nearby α Centauri triple system has one of the most extensive X-ray records of any cosmic object, stretching over 30 years. The primary, α Cen A (G2 V), is a near twin of the Sun, with a similarly soft (1-2 MK) corona. The secondary, α Cen B (K1 V), is more active than the Sun, with a generally harder coronal spectrum. Here…
Mass Outflow in the Seyfert 1 Galaxy NGC 5548
Kaastra, J. S.; Arav, N.; Kraemer, S. B. +4 more
We present a study of the intrinsic UV absorption and emission lines in an historically low-state spectrum of the Seyfert 1 galaxy NGC 5548, which we obtained in 2004 February at high spatial and spectral resolution with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. We isolate a component of emission with a width of 680 k…