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Interplanetary hydrogen absolute ionization rates: Retrieving the solar wind mass flux latitude and cycle dependence with SWAN/SOHO maps
Bertaux, Jean-Loup; Lallement, Rosine; Schmidt, Walter +4 more
We present results of the total hydrogen ionization rate obtained from the inversion of almost 10 years of full-sky maps of the interplanetary Lyman α background measured by the SWAN instrument on SOHO. Thanks to a new estimate of the absolute calibration of the SWAN instrument and its variation during the 10 years of operation of SOHO, we are abl…
Impact of Major Coronal Mass Ejections on Geospace during 2005 September 7-13
Wang, Yuming; Shen, Chenglong; Wang, S. +3 more
We have analyzed five major CMEs originating from NOAA active region (AR) 808 during the period of 2005 September 7-13, when the AR 808 rotated from the east limb to near solar meridian. Several factors that affect the probability of the CMEs' encounter with the Earth are demonstrated. The solar and interplanetary observations suggest that the sec…
The Subparsec-Scale Radio Properties of Southern Starburst Galaxies. I. Supernova Remnants, the Supernova Rate, and the Ionized Medium in the NGC 253 Starburst
Tingay, S. J.; Lenc, E.
Wide-field, very long baseline interferometry observations of the nearby starburst galaxy NGC 253, obtained with the Australian Long Baseline Array, have produced a 2.3 GHz image with a maximum angular resolution of 15 mas (0.3 pc). Six sources were detected, all corresponding to sources identified in higher frequency (>5 GHz) VLA images. One o…
The two Titan stellar occultations of 14 November 2003
Glass, I. S.; Jones, T.; Colas, F. +49 more
We report the observation of two stellar occultations by Titan on 14 November 2003, using stations in the Indian Ocean, southern Africa, Spain, and northern and southern Americas. These occultations probed altitudes between ~550 and 250 km (~1 to 250 µbar) in Titan's upper stratosphere. The light curves reveal a sharp inversion layer near 51…
The Polar Regions of Cassiopeia A: The Aftermath of a Gamma-Ray Burst?
Hwang, Una; Laming, J. Martin; Radics, Balint +2 more
Are the polar regions of Cas A the aftermath of a gamma-ray burst? Probably not, but it is interesting nevertheless to investigate just how close Cas A might have come to generating such an event. Focusing on the northeast jet filaments, we analyze the polar regions of the recently acquired very deep 1 Ms Chandra X-ray observation. We infer that t…
Radio and X-ray variability of young stellar objects in the Coronet cluster
Menten, K. M.; Forbrich, J.; Preibisch, Th.
The Coronet cluster in the nearby R CrA dark cloud offers the rare opportunity to study at least four "class I" protostellar sources as well as one candidate "class 0" source, a Herbig Ae star, and a candidate brown dwarf within a few square arcminutes - most of them detected at radio- and X-ray wavelengths. These sources were observed with the Ve…
p-Mode Propagation through the Transition Region into the Solar Corona. I. Observations
Marsh, M. S.; Walsh, R. W.
Oscillations have long been observed in the sunspot umbral chromosphere and transition region, connected to global p-mode oscillations. These p-modes are thought to undergo mode conversion to slow magnetoacoustic waves in regions of strong magnetic field. More recently, propagating oscillations have also been observed in solar coronal loops. Using…
Role of Sunspot and Sunspot-Group Rotation in Driving Sigmoidal Active Region Eruptions
Alexander, David; Tian, Lirong
We study active region NOAA 9684 (N06L285) which produced an X1.0/3B flare on November 4, 2001 associated with a fast CME (1810 km s−1) and the largest proton event (31 700 pfu) in cycle 23. SOHO/MDI continuum image data show that a large leading sunspot rotated counter-clockwise around its umbral center for at least 4 days prior to the…
The Jet-Disk Connection in AGNs: Chandra and XMM-Newton Observations of Three Powerful Radio-Loud Quasars
Maraschi, L.; Tavecchio, F.; Gliozzi, Mario +2 more
The connection between the accretion process that powers AGNs and the formation of jets is still poorly understood. Here we tackle this issue using new, deep Chandra and XMM-Newton observations of the cores of three powerful radio-loud quasars, 1136-135, 1150+497 (Chandra), and 0723+679 (XMM-Newton), in the redshift range z=0.3-0.8. These sources …
The OB binary HD152219: a detached, double-lined, eclipsing system
Gosset, E.; Rauw, G.; Sana, H.
We present the results of an optical spectroscopic campaign on the massive binary HD152219 located near the core of the NGC6231 cluster. Though the primary to secondary optical brightness ratio is probably about 10, we clearly detect the secondary spectral signature and we derive the first reliable SB2 orbital solution for the system. The orbital …