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A Steady, Radiative-Shock Method for Computing X-Ray Emission from Colliding Stellar Winds in Close, Massive-Star Binaries
Owocki, S. P.; Antokhin, I. I.; Brown, J. C.
We present a practical, efficient, semianalytic formalism for computing steady state X-ray emission from radiative shocks between colliding stellar winds in relatively close (orbital period up to order tens of days) massive-star, binary systems. Our simplified approach idealizes the individual wind flows as smooth and steady, ignoring the intrinsi…
Partial Covering Interpretation of the X-Ray Spectrum of the NLS1 1H 0707-495
Ueda, Yoshihiro; Tanaka, Yasuo; Gallo, Luigi +2 more
The X-ray spectrum of 1H 0707 - 495 obtained with XMM-Newton showing a deep flux drop at ∼ 7 keV (Boller et al. 2002) is studied based on the partial covering concept. The previously inferred extreme iron overabundance can be reduced down to ∼ 3× solar if the hard component gradually steepens at high energies. The spectral shape supports that 1H 0…
Anatomy of a flux transfer event seen by Cluster
Hasegawa, H.; Paschmann, G.; Sonnerup, B. U. Ö.
Data from Cluster are used to study the structure of a flux transfer event (FTE), seen near the northern cusp. We employ Grad-Shafranov reconstruction, using measured fields from all four spacecraft to produce a map of the FTE cross section. The FTE consists of a flux rope of approximate size 1RE and irregular shape, embedded in the mag…
RR Lyrae Stars in the Andromeda Halo from Deep Imaging with the Advanced Camera for Surveys
Ferguson, Henry C.; Brown, Thomas M.; Rich, R. Michael +4 more
We present a complete census of RR Lyrae stars in a halo field of the Andromeda galaxy. These deep observations, taken as part of a program to measure the star formation history in the halo, spanned a period of 41 days with sampling on a variety of timescales, enabling the identification of short- and long-period variables. Although the long-perio…
The ACS Virgo Cluster Survey. II. Data Reduction Procedures
Jordán, Andrés; Tonry, John L.; Côté, Patrick +7 more
The ACS Virgo Cluster Survey is a large program to carry out multicolor imaging of 100 early-type members of the Virgo Cluster using the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope. Deep F475W and F850LP images (~SDSS g and z) are being used to study the central regions of the program galaxies, their globular cluster systems, a…
Coronal Mass Ejection of 15 May 2001: II. Coupling of the Cme Acceleration and the Flare Energy Release
Maričić, D.; Vršnak, B.; Stanger, A. L. +1 more
We analyze the relationship between the dynamics of the coronal mass ejection (CME) of 15 May 2001 and the energy release in the associated flare. The flare took place behind the east limb and was disclosed by a growing system of hot soft X-ray (SXR) loops that appeared from behind the limb around the onset of the rapid acceleration of the CME. Th…
Mapping the inner regions of MCG-6-30-15 with XMM-Newton
Cappi, M.; Ponti, G.; Dadina, M. +1 more
Timing analysis of a ∼95 ks long XMM-Newton observation of the Seyfert 1 galaxy MCG-6-30-15 is presented. Model-independent tools have been used with the intent of resolving the different components that produce the observed flux and spectral variations down to timescales as short as ∼300 s. We find that the fractional variability is possibly due …
X-Ray Sources and Their Optical Counterparts in the Globular Cluster M4
Anderson, Scott F.; Kaspi, Victoria M.; Verbunt, Frank +7 more
We report on the Chandra X-Ray Observatory ACIS-S3 imaging observation of the Galactic globular cluster M4 (NGC 6121). We detect 12 X-ray sources inside the core and 19 more within the cluster half-mass radius. The limiting luminosity of this observation is LX~1029 ergs s-1 for sources associated with the cluster, …
Solar and Heliospheric Phenomena in October-November 2003: Causes and Effects
Petrukovich, A. A.; Zelenyi, L. M.; Yermolaev, Yu. I. +72 more
We present new observational data on the phenomena of extremely high activity on the Sun and in the heliosphere that took place in October-November 2003. A large variety of solar and heliospheric parameters give evidence that the interval under consideration is unique over the entire observation time. Based on these data, comparing them with simil…
The Solar Neighborhood. IX. Hubble Space Telescope Detections of Companions to Five M and L Dwarfs within 10 Parsecs of the Sun
Illingworth, Garth D.; Nelan, Edmund P.; Ardila, David R. +10 more
We report the detections of low-mass companions to five M and L dwarfs within 10 pc of the Sun using the Hubble Space Telescope (HST) Near-Infrared Camera and Multi-Object Spectrometer (NICMOS). Follow-up observations using the HST Advanced Camera for Surveys (ACS) and Fine Guidance Sensor 1r (FGS1r) confirm our NICMOS discoveries of companions to…