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Massive Young Clusters in the Disk of M31
Bellazzini, M.; Galleti, S.; Federici, L. +3 more
We have studied the properties of a sample of 67 very blue and likely young massive clusters in M31 extracted from the Bologna Revised Catalog of globular clusters, selected according to their color [(B-V)0<=0.45] and/or the strength of their Hβ spectral index (Hβ>=3.5 Å). Their existence in M31 has been noted by several authors i…
Can surface magnetic fields reproduce solar irradiance variations in cycles 22 and 23?
Solanki, S. K.; Krivova, N. A.; Wenzler, T.
Total solar irradiance is reconstructed using data from the spectromagnetograph on Kitt Peak for 1992 2003 (covering parts of cycles 22 and 23) and compared with observational data. The model assumes that solar irradiance variations are caused by surface magnetism and its single free parameter is kept at the same value for both cycles. A good corr…
INTEGRAL observation of V 0332+53 in outburst
Santangelo, A.; Walter, R.; Mowlavi, N. +9 more
We present the analysis of a 100 ks INTEGRAL (3-100 keV) observation of the transient X-ray pulsar V 0332+53in outburst. The source is pulsating at PPulse=4.3751±0.0002 s with a clear double pulse from 6 keVto 60 keV. The average flux was ~550 mCrab between 20 keVand 60 keV. We modeled the broad band continuum from 5 keVto 100 keVwith a…
Hubble Space Telescope STIS Observations of the Accreting White Dwarfs in BW Sculptoris, BC Ursae Majoris, and SW Ursae Majoris
Szkody, Paula; Howell, Steve B.; Sion, Edward M. +1 more
We have observed the short-period dwarf novae BW Scl, BC UMa, and SW UMa using the Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS). In all three systems, the white dwarf is the dominant source of far-ultraviolet flux, even though in BC UMa and SW UMa an additional continuum component contributes ~10% and ~20% of the 1400 Å flux,…
High mass X-ray binaries in the LMC: Dependence on the stellar population age and the ``propeller'' effect
Gilfanov, M.; Shtykovskiy, P.
We study the population of compact X-ray sources in the Large Magellanic Cloud using the archival data of the XMM-Newton observatory. The total area of the survey is ≈ 3.8 square degrees with a limiting sensitivity of ≈10-14 erg/s/cm2, corresponding to a luminosity of ≈3× 1033 erg/s at the LMC distance. Out of ∼460…
Changes in the Subsurface Stratification of the Sun with the 11-Year Activity Cycle
Kosovichev, A. G.; Lefebvre, S.
We report on changes in the Sun's subsurface stratification inferred from helioseismology data. Using data from the Solar and Heliospheric Observatory (SOHO) Michelson Doppler Imager (MDI) for the last 9 years and, more precisely, the temporal variation of f-mode frequencies, we have computed the variation in the radius of subsurface layers of the…
Styles and timing of volatile-driven activity in the eastern Hellas region of Mars
Crown, David A.; Bleamaster, Leslie F.; Mest, Scott C.
Recent analyses of Mars Global Surveyor and Mars Odyssey data sets provide new insights into the geologic evolution of the eastern Hellas region of Mars, in particular, the role of volatiles. Here, we present results of our recent work and integrate these with previous studies by various investigators to provide a synthesis of the history of volat…
Stephan's Quintet with XMM-Newton
Pietsch, W.; Breitschwerdt, D.; Trinchieri, G. +1 more
The prototype compact group known as Stephan's Quintet (SQ) was observed with XMM-Newton in order to complement the excellent resolution of Chandra with high sensitivity to extended emission. SQ is a dynamic environment whose main effect, at both X-ray and optical wavelengths, appears to be ISM stripping. This is manifested by: 1) secular evolutio…
New Geoeffective Parameters of Very Fast Halo Coronal Mass Ejections
Cho, K. -S.; Kim, Y. -H.; Moon, Y. -J. +4 more
We have examined the physical characteristics of very fast coronal mass ejections (CMEs) and their geoeffective parameters. For this we consider SOHO LASCO CMEs whose speeds are larger than 1300 km s-1. By examining all SOHO EIT and SOHO LASCO images of the CMEs, we selected 38 front-side very fast CMEs and then examined their associati…
Double Star/Cluster observation of neutral sheet oscillations on 5 August 2004
Balogh, A.; Zhang, T. L.; Nakamura, R. +8 more
Previous Cluster observations have shown that the flapping motions of the Earth's magnetotail are of internal origin and that kink-like waves are emitted from the central part of the tail and propagate toward the tail flanks. The newly launched Double Star Program (DSP) TC-1 satellite allows us to investigate neutral sheet at 10-13 Re in the tail.…