Search Publications
Hybrid simulations of magnetic reconnection initiated in the magnetosheath
Omidi, N.; Sibeck, D. G.; Phan, T.
Interaction of solar wind tangential discontinuities (TDs) with the bow shock may initiate reconnection in the magnetosheath. We employ 2.5-D electromagnetic, hybrid simulations that treat the ions kinetically via particle-in-cell methods and the electrons as a massless fluid to study this interaction. We present results from eight runs correspond…
Simultaneous measurements of Martian plasma boundaries by Rosetta and Mars Express
Barabash, S.; Lundin, R.; Fränz, M. +15 more
We present the first two-spacecraft near-simultaneous observations of the Martian bow shock (BS), magnetic pileup boundary (MPB) and photo-electron boundary (PEB) obtained by the plasma instruments onboard Rosetta and Mars Express during the Rosetta Mars flyby on February 25, 2007. Our observations are compared with shape models for the BS and MPB…
Asymmetry of Helicity Injection Flux in Emerging Active Regions
Alexander, David; Tian, Lirong
Observational and modeling results indicate that typically the leading magnetic field of bipolar active regions (ARs) is often spatially more compact, while more dispersed and fragmented in following polarity. In this paper, we address the origin of this morphological asymmetry, which is not well understood. Although it may be assumed that, in an …
X-Ray Searches for Emission from the WHIM in the Galactic Halo and the Intergalactic Medium
Bregman, Joel N.; Putman, Mary E.; Irwin, Jimmy A. +3 more
At least 50% of the baryons in the local universe are undetected and predicted to be in a hot dilute phase (105-107 K) in low and moderate overdensity environments. We searched for the predicted diffuse faint emission through shadowing observations whereby cool foreground gas absorbs more distant diffuse emission. Observation…
Spectral Variation of the Seyfert 1 Galaxy MCG -6-30-15 Observed with Suzaku
Terashima, Yuichi; Ebisawa, Ken; Inoue, Hajime +3 more
We have investigated the spectral variation of the Seyfert 1 galaxy MCG -6-30-15 observed with Suzaku in 2006 January for three separate periods spreading over fourteen days. We found that the time-averaged continuum energy spectrum between 1 keV and 40 keV can be approximated with a spectral model composed of a direct power-law component, its ref…
Mid-UV Narrow-Band Indices of Evolved Simple Stellar Populations
Bressan, A.; Chavez, M.; Bertone, E. +1 more
We explore the properties of selected mid-ultraviolet (1900-3200 Å) spectroscopic indices of simple stellar populations. We incorporate the high-resolution UVBLUE stellar spectral library into an evolutionary population synthesis code, based on the most recent Padova isochrones. We analyze the trends of UV indices with respect to age and chemical …
Origin of the Local Bubble
Breitschwerdt, Dieter; de Avillez, Miguel A.; Fuchs, Burkhard +1 more
We present a new unbiased search for OB associations in the Solar neighbourhood which have hosted the progenitor stars of the core collapse supernovae responsible for the Local Bubble in the interstellar gas. For this purpose we have analyzed a volume complete set (with a diameter of 400 pc) of B stars drawn from the Hipparcos catalogue and the Ar…
Galaxy evolution by color-log(n) type since redshift unity in the Hubble Ultra Deep Field
Cameron, E.; Driver, S. P.
Aims: We explore the use of the color-log(n) (where n is the global Sérsic index) plane as a tool for subdividing the galaxy population in a physically-motivated manner out to redshift unity. We thereby aim to quantify surface brightness evolution by color-log(n) type, accounting separately for the specific selection and measurement biases against…
Field line distribution of density at L=4.8 inferred from observations by CLUSTER
Kistler, L. M.; Mouikis, C.; Décréau, P. +8 more
For two events observed by the CLUSTER spacecraft, the field line distribution of mass density ρ was inferred from Alfvén wave harmonic frequencies and compared to the electron density ne from plasma wave data and the oxygen density nO+ from the ion composition experiment. In one case, the average ion mass M≈ρ/ne w…
Low-Mass X-ray Binaries and Globular Clusters in Early-Type Galaxies. II. Globular Cluster Candidates and Their Mass-Metallicity Relation
Humphrey, Philip J.
We present an astrometry and photometry catalogue of globular cluster (GC) candidates detected with the Hubble Space Telescope Wide Field Planetary Camera 2 in a sample of 19 early-type galaxies, appropriate for comparison with the low-mass X-ray binary populations observed with Chandra. In a companion paper, we present the Chandra data and invest…