Search Publications
Magnetic Energy and Helicity Budgets in the Active-region Solar Corona. II. Nonlinear Force-free Approximation
Georgoulis, Manolis K.; Tziotziou, Kostas; Raouafi, Nour-Eddine
Expanding on an earlier work that relied on linear force-free (LFF) magnetic fields, we self-consistently derive the instantaneous free magnetic energy and relative magnetic helicity budgets of an unknown three-dimensional nonlinear force-free (NLFF) magnetic structure extending above a single known lower-boundary magnetic field vector. The propos…
A Comparison between the Stellar and Dynamical Masses of Six Globular Clusters
Bellazzini, M.; Sollima, A.; Lee, J. -W.
We present the results of a comprehensive analysis of the structure and kinematics of six Galactic globular clusters. By comparing the results of the most extensive photometric and kinematical surveys available to date with suitable dynamical models, we determine the stellar and dynamical masses of these stellar systems taking into account the eff…
Tracking down the Source Population Responsible for the Unresolved Cosmic 6-8 keV Background
Lehmer, B. D.; Alexander, D. M.; Bauer, F. E. +10 more
Using the 4 Ms Chandra Deep Field-South (CDF-S) survey, we have identified a sample of 6845 X-ray-undetected galaxies that dominates the unresolved ≈20%-25% of the 6-8 keV cosmic X-ray background (XRB). This sample was constructed by applying mass and color cuts to sources from a parent catalog based on GOODS-South Hubble Space Telescope z-band im…
Spatial Analysis of the Polycyclic Aromatic Hydrocarbon Features Southeast of the Orion Bar
Boersma, C.; Allamandola, L. J.; Rubin, R. H.
Polycyclic aromatic hydrocarbon (PAH) and dust emission features between 10 and 37 µm, observed with Spitzer at 11 positions southeast of the Bright Bar (BB) in Orion, are analyzed and connected to atomic and H2 lines reported earlier. Variations at these positions indicate changes in local conditions and materials sampled. The ma…
Patterns of accumulation and flow of ice in the mid-latitudes of Mars during the Amazonian
Head, James W.; Fassett, Caleb I.; Dickson, James L.
Evidence has accumulated that non-polar portions of Mars have undergone significant periods of glaciation during the Amazonian Period. This evidence includes tropical mountain glacial deposits, lobate debris aprons, lineated valley fill, concentric crater fill, pedestal craters, and related landforms, some of which suggest that ice thicknesses exc…
The massive protostar W43-MM1 as seen by Herschel-HIFI water spectra: high turbulence and accretion luminosity
Braine, J.; Bontemps, S.; van Dishoeck, E. F. +7 more
Aims: We present Herschel-HIFI observations of 14 water lines in W43-MM1, a massive protostellar object in the luminous star-cluster-forming region W43. We place our study in the more general context of high-mass star formation. The dynamics of these regions may be represented by either the monolithic collapse of a turbulent core, or competit…
On the Role of the Background Overlying Magnetic Field in Solar Eruptions
Wiegelmann, T.; Patsourakos, S.; Nindos, A.
The primary constraining force that inhibits global solar eruptions is provided by the overlying background magnetic field. Using magnetic field data from both the Helioseismic and Magnetic Imager aboard the Solar Dynamics Observatory and the spectropolarimeter of the Solar Optical Telescope aboard Hinode, we study the long-term evolution of the b…
Comet-like mineralogy of olivine crystals in an extrasolar proto-Kuiper belt
Waters, L. B. F. M.; Ivison, R. J.; Blommaert, J. A. D. L. +20 more
Some planetary systems harbour debris disks containing planetesimals such as asteroids and comets. Collisions between such bodies produce small dust particles, the spectral features of which reveal their composition and, hence, that of their parent bodies. A measurement of the composition of olivine crystals (Mg2-2xFe2xSiO
Chemical and Kinematical Properties of Blue Straggler Stars and Horizontal Branch Stars in NGC 6397
Dalessandro, E.; Contreras Ramos, R.; Mucciarelli, A. +4 more
We used three sets of high-resolution spectra acquired with the multifiber facility FLAMES at the Very Large Telescope of the European Southern Observatory to investigate the chemical and kinematical properties of a sample of 42 horizontal branch (HB) stars, 18 blue straggler stars (BSSs), and 86 main-sequence (MS) turnoff (TO) and sub-giant branc…
Reconnection at the magnetopause of Saturn: Perspective from FTE occurrence and magnetosphere size
Lai, H. R.; Russell, C. T.; Wei, H. Y. +2 more
Flux transfer events observed at Mercury, Earth, and Jupiter are attributed to spatially and temporally limited events in which the magnetosheath and magnetospheric magnetic field become interconnected and magnetic flux is transported from the dayside to the lobes of the magnetotail. Examination of the Saturnian magnetopause at local times from 10…