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Improved bow shock model with dependence on the IMF strength
Němeček, Z.; Šafránková, J.; Jelínek, K. +2 more
The presence of the bow shock in front of an obstacle immersed into a supersonic flow of collisionless plasma has been theoretically predicted and experimentally confirmed more than 40 years ago. However, in spite of a great effort of theoreticians and experimenters, we are still not able to predict the bow shock location under varying upstream co…
Quasi-monochromatic ULF foreshock waves as observed by the four-spacecraft Cluster mission: 1. Statistical properties
Balogh, A.; Dandouras, I.; Eastwood, J. P. +2 more
Cluster data are used to study the statistics of a particular type of foreshock wave: quasi-monochromatic ultra-low-frequency (ULF) waves with characteristic periods of 30 s in the spacecraft frame. On the basis of a large set of foreshock observations made in 2001 with spacecraft separations ∼600 km, the intrinsic properties of the waves are foun…
Thick disks and halos of spiral galaxies M 81, NGC 55 and NGC 300
Tikhonov, N. A.; Galazutdinova, O. A.; Drozdovsky, I. O.
By using images from the HST/WFPC2/ACS archive, we have analyzed the spatial distribution of the AGB and RGB stars along the galactocentric radius of nearby spiral galaxies M 81, NGC 300 and NGC 55. Examining color-magnitude diagrams and stellar luminosity functions, we gauge the stellar contents of the surroundings of the three galaxies. The red …
Gemini Near Infrared Spectrograph Observations of the Central Supermassive Black Hole in Centaurus A
Gebhardt, Karl; Richstone, Douglas; Bergmann, Marcel +1 more
The Gemini Near Infrared Spectrograph on Gemini South unlocks new possibilities to study the central black holes (BHs) in dusty galaxies that have been inaccessible to previous BH studies. We exploit good near-infrared seeing to measure the central BH of Centaurus A (NGC 5128). We measure the stellar kinematics of NGC 5128 using the region around …
Revealing the Interaction between the X-Ray Gas of Starburst Galaxy UGC 6697 and the Hot Intracluster Medium of A1367
Vikhlinin, A.; Sun, M.
We present the result from a Chandra observation of an X-ray-luminous starburst galaxy, UGC 6697, which is embedded in the northwest hot region of A1367 (5-6 keV). A very sharp X-ray edge (~13-fold surface brightness jump) at the southeast and a long tail (at least 60 kpc from the nucleus) at the northwest of the galaxy are detected, as expected i…
Integral field spectroscopy of the ultraluminous X-ray source Holmberg II X-1
Greiner, J.; Costantini, E.; Roth, M. +10 more
We present optical integral field observations of the H II region containing the ultraluminous X-ray source Holmberg II X-1. We confirm the existence of an X-ray ionized nebula as the counterpart of the source owing to the detection of an extended He II λ4686 region (21× 47 pc) at the Chandra ACIS-S position. An extended blue object with a size of…
The Acoustic Showerglass. I. Seismic Diagnostics of Photospheric Magnetic Fields
Braun, D. C.; Lindsey, Charles
A problem of major interest in the helioseismology of active regions is the acoustics of magnetic photospheres and shallow subphotospheres. Magnetic fields suppress the photospheric signatures of acoustic waves impinging onto them from the underlying solar interior and shift their phases. The phase shifts function as a sort of acoustic showerglass…
Post-glitch variability in the anomalous X-ray pulsar 1RXSJ170849.0-400910
Haberl, F.; Stella, L.; Rea, N. +5 more
Here we report on the first XMM-Newton observation of the anomalous X-ray pulsar 1RXSJ170849.0-400910. The source was observed in 2003 August, and was found at a flux level factor of about 2 lower than previous observations. Moreover, a significant spectral evolution appears to be present, the source exhibiting a much softer spectrum than in the p…
On the possibility of measuring the solar oblateness and some relativistic effects from planetary ranging
Iorio, L.
In this paper we first calculate the post-Newtonian gravitoelectric secular rate of the mean anomaly of a test particle freely orbiting a spherically symmetric central mass. Then, we propose a novel approach to suitably combine the presently available planetary ranging data to Mercury, Venus and Mars in order to determine, simultaneously and indep…
On the Origin of Exponential Disks at High Redshift
Elmegreen, Bruce G.; Elmegreen, Debra Meloy; Vollbach, David R. +2 more
The major-axis and ellipse-fit intensity profiles of spiral galaxies larger than 0.3" in the Hubble Space Telescope Ultra Deep Field (UDF) are generally exponential, whereas the major-axis profiles in irregular disk galaxies, called clump clusters in our previous studies, are clearly not. Here we show that the deprojected positions of star-forming…