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Small-scale structures in the far-infrared background
Laureijs, R. J.; Klaas, Ulrich; Herbstmeier, Uwe +6 more
Four fields with areas ranging from 80 to 2000 arcmin(2) have been mapped with the photometer on board of the Infrared Space Observatory (ISO) at 90 and around 180mu m in regions of bright and faint cirrus. We examined the spatial characteristics of the infrared background emission with high spatial resolution and found that the fluctuations in th…
A Possible Mechanism for the Origin of Emerging Flux in the Sunspot Moat
Title, A.; Shine, R.; Sakai, J. I. +1 more
Mass and energy flow near sunspots are associated with the emergence of magnetic flux, which then moves outward in the sunspot moat. We present results of analytical and numerical studies of the interaction of horizontal magnetic flux and plasma flows in three-dimensional geometry. We show that nonlinear coupling of flux and plasma flows in the pr…
The Ultracompact H II Region G5.97-1.17: an Evaporating Circumstellar Disk in M8
Henning, T.; Stecklum, B.; Hayward, T. L. +4 more
We present new high spatial resolution optical, infrared, and radio observations of G5.97-1.17, an ultracompact H ii region 2.7" distant from the O7 star Herschel 36 in the center of M8, the Lagoon Nebula. Infrared imaging was obtained using the adaptive optics system ADONIS on the ESO 3.6 m telescope and a thermal-IR camera on the Hale 5 m; optic…
Kinematic signatures of violent formation of galactic OB associations from HIPPARCOS measurements
Torra, J.; Comeron, F.; Gomez, A. E.
Proper motions measured by Hipparcos confirm the large anomalous velocities of the OB associations located around the Cygnus Superbubble (Cygnus OB1, OB3, OB7, and OB9), and reveal a clearly organized expanding pattern in Canis Major OB1. At the distances of these associations, the organized velocity patterns imply LSR velocities of up to ~ 60 km …
HST/GHRS Observations of the Velocity Structure of Interplanetary Hydrogen
Bertaux, Jean-Loup; Clarke, John T.; Lallement, Rosine +3 more
We present high-resolution spectra of the emission-line profile of inflowing interplanetary hydrogen atoms along lines of sight with the Earth orbital motion upwind (into the flow), downwind, and across the flow to Doppler-shift the line from the geocoronal emission. The line-center positions, in comparison with hot-model profiles, confirm that th…
Hubble Space Telescope WFPC2 Imaging of FS Tauri and Haro 6-5B
Ballester, Gilda E.; Krist, John E.; Crisp, David +14 more
We have observed the field of FS Tauri (Haro 6-5) with the Wide Field Planetary Camera 2 on the Hubble Space Telescope. Centered on Haro 6-5B and adjacent to the nebulous binary system of FS Tauri A there is an extended complex of reflection nebulosity that includes a diffuse, hourglass-shaped structure. H6-5B, the source of a bipolar jet, is not …
On the accuracy of helioseismic determination of solar helium abundance
Dziembowski, W. A.; Goode, Philip R.; Richard, O. +1 more
The Helium abundance in the solar envelope is one of the most important seismic observables. We investigate the accuracy of its determination taking into account uncertainties in the data and in the inversion procedure. Our best value for the helium abundance in the photosphere is Ysun=0.248. The estimated uncertainty of 0.002 is domina…
Long-term monitoring of active stars. VIII. UBV(RI)_(c) photometry collected in February 1992
Cutispoto, G.
As a part of an extensive program focusing on the global properties and evolution of active stars, high-precision UBV(RI)_c photometry of 31 selected stars, collected at the European Southern Observatory over the 14-29 February 1992 interval, is presented. Significant evolution of the light curves, period variations and evidence for long-term vari…
An Infrared Search for Star-forming Galaxies at Z > 2
Teplitz, Harry I.; Malkan, M.; McLean, I. S.
We report the cumulative results of an ongoing near-infrared search for redshifted Hα emission from normal galaxies at z > 2. An infrared search reduces the bias due to reddening. Using narrowband imaging with the Near Infrared Camera on the Keck I 10 m telescope, a survey area of almost 12 arcmin2 has been covered. Target regions we…
Ionization Structure in the 30 Doradus Nebula as seen with Hubble Space Telescope Wide Field Planetary Camera 2
Watson, A. M.; Holtzman, J. A.; Stapelfeldt, K. R. +15 more
Using the Hubble Space Telescope (HST) and Wide Field Planetary Camera 2, we have imaged the central 20 pc of the giant H ii region 30 Doradus Nebula in three different emission lines. The images allow us to study the nebula with a physical resolution that is within a factor of 2 of that of typical ground-based observations of Galactic H ii region…