Search Publications
Heliospheric conditions that affect the interstellar gas inside the heliosphere
Möbius, E.; Bzowski, M.; Lallement, R. +9 more
The interstellar gas that flows through the heliosphere is strongly affected by ionization close to the Sun, in particular solar photoionization, electron impact, and charge exchange. Therefore, the interpretation of any observation of interstellar gas in the inner heliosphere hinges upon the accurate knowledge of these effects and their variation…
Hubble Space Telescope Observations of cD Galaxies and Their Globular Cluster Systems
Jordán, Andrés; Minniti, Dante; Marzke, Ronald O. +3 more
We have used WFPC2 on the Hubble Space Telescope (HST) to obtain F450W and F814W images of four cD galaxies (NGC 541 in Abell 194, NGC 2832 in Abell 779, NGC 4839 in Abell 1656, and NGC 7768 in Abell 2666) in the range 5400 km s-1<~cz<~8100 km s-1. For NGC 541, the HST data are supplemented by ground-based B and I image…
The Effective Temperatures of Hot Stars. II. The Early-O Types
Bianchi, Luciana; Garcia, Miriam
We derived the stellar parameters of a sample of Galactic early-O type stars by analyzing their UV and far-UV spectra from the Far Ultraviolet Spectroscopic Explorer (905-1187 Å), the International Ultraviolet Explorer, the Hubble Space Telescope STIS, and the Orbiting and Retrievable Far and Extreme Ultraviolet Spectrometer (1200-2000 Å). The dat…
Ultralow Iron Abundances in the Distant Hot Gas in Galaxy Groups
Buote, David A.; Brighenti, Fabrizio; Mathews, William G.
A new XMM observation of the outer regions of the galaxy group NGC 5044 indicates hot gas iron abundances of only ZFe/Zsolar~0.15 between r=0.2rvir and 0.4rvir. While the total baryon mass within the virial radius may be close to the cosmic mean value observed in rich clusters, the ratio of total iron ma…
Menzel 3: a Multipolar Nebula in the Making
Guerrero, Martín A.; Chu, You-Hua; Miranda, Luis F.
The nebula Menzel 3 (Mz 3) has arguably the most complex bipolar morphology, consisting of three nested pairs of bipolar lobes and an equatorial ellipse. Its three pairs of bipolar lobes share the same axis of symmetry but have very different opening angles and morphologies: the innermost pair of bipolar lobes shows closed-lobe morphology, whereas…
An XMM-Newton observation of the massive binary HD 159176
Gosset, E.; Owocki, S. P.; Rauw, G. +4 more
We report the analysis of an XMM-Newton observation of the close binary HD 159176 (O7 V + O7 V). The observed LX/Lbol ratio reveals an X-ray luminosity exceeding by a factor ∼7 the expected value for X-ray emission from single O-stars, therefore suggesting a wind-wind interaction scenario. EPIC and RGS spectra are fitted cons…
Prominence corona transition region plasma diagnostics from SOHO observations
Vial, J. -C.; Rovira, M.; Cirigliano, D.
New results concerning prominence observations and in particular the prominence-corona transition region (PCTR) are presented. In order to cover a temperature range from 2 × 104 to 7 × 105 K, several emission lines in many different ionization states were observed with SUMER and CDS on board SOHO. EM and DEM were measured thr…
Multi-instrument observations of the ionospheric counterpart of a bursty bulk flow in the near-Earth plasma sheet
Klecker, B.; Nakamura, R.; Rème, H. +4 more
Available from http://www.copernicus.org/site/EGU/annales/22/4/1061.htm?FrameEngine=false;
Does Solar Structure Vary with Solar Magnetic Activity?
Basu, Sarbani; Mandel, Anna
We present evidence that solar structure changes with changes in solar activity. We find that the adiabatic index, Γ1, changes near the second helium ionization, i.e., at a depth of about 0.98 Rsolar. We believe that this change is a result of the change in the effective equation of state caused by magnetic fields. Inversions…
The complex soft X-ray spectrum of NGC 4151
Schurch, N. J.; Warwick, R. S.; Kahn, S. M. +1 more
We present a detailed analysis of the complex soft X-ray spectrum of NGC 4151 measured by the RGS instruments on board XMM-Newton. The XMM-Newton RGS spectra demonstrate that the soft X-ray emission is extremely rich in X-ray emission lines and radiative recombination continua (RRC), with no clear evidence for any underlying continuum emission. Li…