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Optical and Infrared Images and Spectroscopy of the HH 168 Bubble in Cepheus A
Hartigan, Patrick; Bally, John; Morse, Jon
We present new optical emission-line and continuum images taken with the Hubble Space Telescope of the shocked bubble HH 168 (GGD 37) associated with the massive star formation region Cepheus A. The new images clearly resolve the interface between the molecular flow, defined by near-IR images of H2, and the shocked, optically emitting g…
The quantum efficiency of pn-detectors from the near infrared to the soft X-ray region
Hartmann, R.; Stephan, K. -H.; Strüder, L.
The quantum efficiency of back-illuminated silicon pn-junction detectors is evaluated in the spectral range from 1.2 to 1400 eV, comprising the near infrared, visible, ultraviolet and soft X-ray regions. The calibrations are performed with the same device over the entire measured range, thus eliminating technological variations of the entrance win…
Charged-Particle Resonance Conditions and Transport Coefficients in Slab-Mode Waves
Vainio, R.
Transport of charged particles in cold plasma is considered. The full dispersion relation for slab-mode waves is employed, and the quasi-linear particle scattering is discussed. Previous results of the dispersive-wave model on the ion mean free path are recalled and further developed. For small cross-helicities, the model predicts ion mean free pa…
Secondary Fragmentation of the Solar and Heliospheric Observatory Sungrazing Comets at Very Large Heliocentric Distance
Sekanina, Zdenek
The temporal distribution of the Kreutz group of sungrazing comets has been known to have an episodic character on timescales from weeks to tens of years. With the large number of minor members of this group being nowadays discovered in images taken with the Solar and Heliospheric Observatory coronagraphs, it has become apparent that the distribut…
ASCA (and HST) observations of NLS1s
Leighly, Karen M.
The study of NLS1s using ASCA has many advantages. A representative sample can be studied; to date, observations of more than 30 NLS1s have been made. ASCA observations are conducted contiguously, so their X-ray variability properties can be studied systematically. ASCA detectors have a broad band pass and moderate energy resolution, properties wh…
A New Look at Globular Cluster Colors in NGC 3311 and the Case for Exclusively Metal-rich Globular Cluster Systems
Larsen, S. S.; Kissler-Patig, M.; Brodie, J. P.
NGC 3311, the central cD galaxy in the Hydra Cluster, was previously thought to host the most metal-rich globular cluster system known. Ground-based Washington photometry had indicated the almost complete absence of the population of globular clusters near [Fe/H]~-1 dex; these globular clusters are normally dominant in the metallicity distribution…
A Close-Separation Double Quasar Lensed by a Gas-rich Galaxy
White, Richard L.; Wisotzki, Lutz; Gregg, Michael D. +5 more
In the course of a Cycle 8 snapshot imaging survey with the Space Telescope Imaging Spectrograph (STIS), we have discovered that the z=1.565 quasar HE 0512-3329 is a double with image separation 0.644", differing in brightness by only 0.4 mag. This system is almost certainly gravitationally lensed. Although separate spectra for the two images have…
The Infrared Einstein Ring in the Gravitational Lens MG J1131+0456 and the Death of the Dusty Lens Hypothesis
Peng, C. Y.; Keeton, C. R.; Kochanek, C. S. +6 more
We have obtained and modeled NICMOS images of the Einstein ring lens system MG J1131+0456, which show that its lens galaxy is an H=18.6 mag, transparent, early-type galaxy at a redshift of zl~=0.84 it has a major axis effective radius Re=0.7"+/-0.1", projected axis ratio b/a=0.6+/-0.1, and major axis P.A.=55deg+/-9…
Infrared, radio and optical variability of the BL Lacertae object 2007+777
Quirrenbach, A.; Wagner, S. J.; Zensus, J. A. +8 more
We present infrared observations at wavelengths of 60 and 100 mu m and contemporaneous radio (five frequencies) and optical (R band) monitoring of the BL Lac object 2007+777. During a three-week campaign with the ISO, the VLA, the Effelsberg 100 m radio telescope, and optical telescopes in Heidelberg and on Calar Alto, Spain, we observed variabili…
A detailed spectroscopic analysis of varepsilon Per. I. Determination of the orbital parameters and of the frequencies
Mathias, P.; Aerts, C.; De Cat, P. +1 more
We present the analysis of 445 high signal-to-noise spectra of the Si III triplet at 4553 Ä, 4568 Ä, 4575 Ä of the line-profile variable star varepsilon Persei. The data were gathered during 14 consecutive nights and fully cover the orbital cycle of the binary. The orbital parameters that we derive from our data for the close binary are in full ag…