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Hubble Space Telescope STIS Spectroscopy of the Lyα Emission Line in the Central Dominant Galaxies in A426, A1795, and A2597: Constraints on Clouds in the Intracluster Medium
Koekemoer, Anton M.; Baum, Stefi A.; Mack, Jennifer +2 more
We report on HST STIS spectra of the Lyα emission in the central dominant galaxies in three rich clusters of galaxies. We find evidence for a population of clouds in the intracluster medium. We detect 10 Lyα absorption systems toward the nucleus of NGC 1275 with columns of N(HI)~1012-1014 cm-2. These columns would …
A Spectroscopic and Photometric Study of NGC 2685, the Prototype Polar-Ring Galaxy
Moiseev, A. V.; Burenkov, A. N.; Hagen-Thorn, V. A. +3 more
We present and analyze spectroscopic and photometric observations for NGC 2685, the prototype polar-ring galaxy. The spectroscopic data were acquired using the 6 m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences with the UAGS spectrograph and a scanning Fabry-Perot interferometer, while the photometric analysi…
A Chandra Observation of the Diffuse Emission Centered on the Low-Mass X-Ray Binary 4U 1755-33
McClintock, Jeffrey E.; Miller, Jon M.; Murray, Stephen S. +1 more
We present an analysis of a Chandra observation of the field surrounding the low-mass X-ray binary 4U 1755-33, which has been in quiescence since 1996. In 2003, Angelini & White reported the appearance of a narrow 7'-long jetlike feature centered on the position of 4U 1755-33 using the XMM-Newton telescope. Although the source and jet are not …
Heliospheric energetic neutral atoms as a means to determine the anomalous cosmic ray spectrum at the termination shock
Hsieh, K. C.; Hilchenbach, M.; Czechowski, A.
We demonstrate the possibility of deriving the anomalous cosmic ray (ACR) spectrum at the solar wind termination shock and the strength of the shock using energetic neutral H and He atoms (ENA) measurements at 1 AU. Assuming that the energetic neutral atoms detected by CELIAS/HSTOF on board SOHO are of ACR origin, we consider χ2 fits to…
New beta Cephei and SPB Stars Discovered in Hipparcos Photometry
Molenda-Zakowicz, J.; Polubek, G.
We discuss 34 stars for which we detected new frequencies in Hipparcos Hp magnitudes. 13 of these stars are variables discovered in this paper. For 20 stars, we derive log T_eff and log g from Stromgren or Geneva photometry.
We classify one new beta Cep star, HIP 88352, two new beta Cep suspects, HIP 54753 and 88123, four new SPBs, HIP 1030, …Erratum: The XMM Large-Scale Structure survey: an initial sample of galaxy groups and clusters to a redshift z < 0.6
Altieri, B.; Valtchanov, I.; Pierre, M. +14 more
We present X-ray and optical spectroscopic observations of twelve galaxy groups and clusters identified within the XMM Large-Scale Structure (LSS) survey. Groups and clusters are selected as extended X-ray sources from a 3.5 deg2 XMM image mosaic above a flux limit 8e-15 ergs/s/cm2 in the [0.5-2] keV energy band. Deep BVRI images and multi-object …
Correlation between ground-based observations of substorm signatures and magnetotail dynamics
Lester, M.; Owen, C. J.; Dunlop, M. +8 more
We present a substorm event study using the four Cluster spacecraft in combination with ground-based instruments, in order to perform simultaneous observations in the ionosphere and magnetotail. We show good correlation between substorm signatures on the ground and in the magnetotail, even though data from the northern-ground and southern-tail hem…
Bouncing ion clusters in the plasma sheet boundary layer observed by Cluster-CIS
Lundin, R.; Dandouras, I.; RèMe, H. +10 more
We report on ion beams injected into the plasma sheet boundary layer (at or near the separatrix) at distances >39 RE and up to 169 RE that bounced several times back and forth (up to three echoes) while remaining in coherent bunches before thermalizing in the central plasma sheet. These bouncing ion clusters (BIC) interact…
HST Imaging of MEGA Microlensing Candidates in M31
Crotts, Arlin P. S.; Kuijken, Konrad; Widrow, Lawrence M. +5 more
We investigate HST/ACS and WFPC2 images at the positions of five candidate microlensing events from a large survey of variability in M31 (MEGA). Three closely match unresolved sources, and two produce only flux upper limits. All are confined to regions of the color-magnitude diagram where stellar variability is unlikely to be easily confused with …
Reverse convection and cusp proton aurora: Cluster, polar and image observation
Zong, Q. -G.; Daly, P. W.; Mende, S. B. +4 more
On April 21, 2001 an interplanetary CME started to interact with the magnetosphere when CLUSTER spacecraft were travelling in the cusp region. This interaction produced a strong magnetic storm ( Dst = 103 nT) at Earth. Cusp proton aurora was caused by the leading phase of the CME. Cusp proton aurora generally appear during northward IMF…