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Multiwavelength Imaging and Long-Slit Spectroscopy of the Planetary Nebula NGC 6884: The Discovery of a Fast Precessing, Bipolar Collimated Outflow
Guerrero, Martín A.; Miranda, Luis F.; Torrelles, José M.
We present Hα, [N II] lambda6583, [O III] lambda5007 ground-based images, Hubble Space Telescope (HST) (V band) archival images, VLA-A 3.6 cm continuum data, and high-resolution long-slit spectra of the planetary nebula NGC 6884. The VLA and HST images show an extremely knotty and filamentary nebula with an elliptical central structure also recogn…
Polarization of Light Scattered by Cometary Dust Particles: Observations and Tentative Interpretations
Levasseur-Regourd, A. -Chantal
Analysis of the polarization of light scattered by cometary particles reveals similarities amongst the phase curves, together with some clear differences: i) comets with a strong silicate emission feature present a high maximum in polarization, ii) the polarization is always slightly lower than the average in inner comae and stronger in jet-like s…
Pulsation models of delta Scuti variables. II. delta Scuti stars as precise distance indicators
Christensen-Dalsgaard, J.; Petersen, J. O.
The Hipparcos period-luminosity relation for high-amplitude delta Scuti stars is discussed as an average period-luminosity-colour-metallicity relation comparing the Hipparcos sample of calibrating stars with a more representative sample taken from McNamara (1997). The Hipparcos relation includes systematic effects of both colour and metallicity an…
The C IV Absorption-Mg II Kinematics Connection in <Z> ~ 0.7 Galaxies
Charlton, Jane C.; Schneider, Donald P.; Steidel, Charles C. +4 more
We have examined Faint Object Spectrograph data from the Hubble Space Telescope archive for C IV λλ1548, 1550 absorption associated with 40 Mg II λλ2796, 2803 absorption-selected galaxies at 0.4<=z<=1.4. We report a strong correlation between Mg II kinematics, measured in ~6 km s-1 resolution HIRES/Keck spectra, and Wr(…
Hubble Space Telescope Faint Object Camera Spectroscopy of the Narrow-Line Region of NGC 4151. I. Gas Kinematics
Axon, David J.; Marconi, A.; Macchetto, F. D. +2 more
We present the results from a detailed kinematic analysis of both ground-based, and Hubble Space Telescope (HST)/Faint Object Camera long-slit spectroscopy at subarcsecond spatial resolution of the narrow-line region (NLR) of NGC 4151. In agreement with previous work, the extended emission gas (R>4") is found to be in normal rotation in the gal…
Exploring the dynamical nature of the lower solar chromosphere
Doyle, J. G.; Banerjee, D.; O'Shea, E. +1 more
We examine spectral time-series of two lower-chromospheric lines (N i 1319 Ä and C ii 1335 Ä) observed with the SUMER instrument on the SOHO spacecraft. We point out differences between (intensity and velocity) power spectra of network and internetwork regions and argue that the behaviour resembles that of Ca ii power spectra. No significant phase…
The extended emission-line region of the Seyfert galaxy Mrk 573
Falcke, H.; Durret, F.; Wilson, A. S. +3 more
We present the results of observations of the extended emission-line region of the Seyfert 2 galaxy Mrk 573, obtained using the WFPC2 on board HST and the TIGER integral field spectrograph on the CFHT. We describe and use a new `guided' deconvolution technique in which the spatial resolution of the TIGER data cubes is improved, allowing us to obta…
Calibration of Hubble Space Telescope WFPC2 Emission-Line Filters
O'Dell, C. R.; Doi, Takao
The results of calibration of the primary emission-line filters of the Hubble Space Telescope WFPC2 are presented in a form which allows observers to easily calculate emission-line surface brightnesses for Hα, Hβ, [O III] λ5007, and [N II] λ6583. The Hα and [N II] filters pass both lines in such a way that observations in both are necessary to obt…
Star-forming regions near GRB 990123
Hjorth, Jens; Holland, Stephen
We reduced the Hubble Space Telescope Space Telescope Imaging Spectrograph images of the gamma-ray burst
The stellar content of soft X-ray surveys. II. Cross-correlation of the ROSAT All-Sky Survey with the Tycho and Hipparcos catalogs
Schmitt, J. H. M. M.; Motch, C.; Guillout, P. +3 more
We present the result of the cross-correlation of the ROSAT All-Sky Survey with the Tycho and Hipparcos catalogs. The constructed RASS - Tycho (RasTyc) and RASS - Hipparcos (RasHip) samples respectively consist of 13 875 and 6 200 matches and represent the largest and most comprehensive samples of stellar X-ray sources constructed so far. The X-ra…