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Properties of Dust Grains in Planetary Nebulae. I. The Ionized Region of NGC 6445
Martin, P. G.; Ferland, Gary J.; Van de Steene, Griet C. +3 more
One of the factors influencing the spectral evolution of a planetary nebula is the fate of the dust grains that are emitting the infrared continuum. Several processes have been proposed that either destroy the grains or remove them from the ionized region. To test whether these processes are effective, we study new infrared spectra of the evolved …
Young Stellar Nuclei in the Lenticular Galaxies. II. NGC 7280
Sil'chenko, O. K.; Afanasiev, V. L.
We have undertaken bidimensional spectroscopy of the central part of the nearby lenticular galaxy NGC 7280 with the Multi-Pupil Fiber Spectrograph of the 6 m telescope of the Special Astrophysical Observatory. We find a rather young stellar nucleus, with a mean population age of 1.5+/-0.5 Gyr, which is more metal-rich than the bulge at R~1 kpc by …
Near-infrared probing of embedded structures in starburst and Seyfert galaxies
Martinet, L.; Martin, P.; Wozniak, H. +2 more
Surface photometry in the J and K' bands of 15 southern Seyfert or starburst galaxies is presented. The detailed central morphology and structural properties of these objects were analyzed by fitting ellipses to isophotes. New central peculiar structures have been identified like, for instance, three double-barred systems (ESO 215-G031;…
Solar and Heliospheric Observatory Sungrazing Comets with Prominent Tails: Evidence on Dust-Production Peculiarities
Sekanina, Zdenek
A preliminary examination of the tails of 11 Solar and Heliospheric Observatory (SOHO) sungrazers, observed between 3 and 20 Rsolar on their approach to the Sun, provides information on dust ejected from these comets and on the forces to which the microscopic grains are subjected. Images taken at times of the SOHO spacecraft's transit a…
Follow-up photometry of six new beta Cephei stars discovered from the HIPPARCOS mission
Aerts, C.
We present ground-based follow-up photometry in the Geneva seven-colour photometric system of six new candidate beta Cep stars. The variability of these objects was originally found from the HIPPARCOS mission. From the new data we are able to confirm their beta Cep-type nature, to detect the pulsational frequencies and to identify most of the degr…
Hubble Space Telescope STIS Observations of the Cygnus Loop: Spatial Structure of a Nonradiative Shock
Blair, William P.; Raymond, John C.; Long, Knox S. +1 more
We present a spatially resolved ultraviolet spectrum of a nonradiative shock front in the Cygnus Loop, obtained with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. The spectrum covers the wavelength range 1118-1716 Å with an effective spectral resolution of ~12 Å. The 0.1" spatial resolution of these data provides a …
The Formation of a Multiple Planetary Nebula:Hubble Space Telescope/WFPC2 Observations of KJPN 8
López, J. A.; Steffen, W.; Meaburn, J. +3 more
KjPn 8 is an extreme polypolar planetary nebula with a large-scale structure characterized by a giant biconical envelope. Spasmodic bipolar ejections in changing directions have occurred over thousands of years to create this peculiar nebula. Narrowband images of the core of KjPn 8 have now been obtained with the Wide Field Planetary Camera 2 on b…
Latitudinal Profiles of the Jovian IR Emissions of H +3 at 4 µm with the NASA Infrared Telescope Facility: Energy Inputs and Thermal Balance
Achilleos, N.; Miller, S.; Prangé, R. +2 more
We present ground-based observations of the jovian ionospheric H +3 emission at 4 micrometers, using the CSHELL facility long-slit spectrograph at the NASA Infrared Telescope Facility (IRTF) in Hawaii. The data were obtained during four consecutive nights from July 13 to July 16, 1996. The 30-arcsec length slit of the spectro…
Spectral energy distributions of FR I nuclei and the FR I/BL Lac unifying model
Capetti, A.; Chiaberge, M.; Celotti, A. +2 more
We consider archival ROSAT and Hubble Space Telescope (HST) observations of five FR I radio galaxies and isolate their nuclear emission from that of the host galaxy. This enables us to determine the spectral energy distributions (SEDs) of their nuclei spanning the region from the radio to the X-ray band. They cannot be described as single power la…
A Broad 22 Micron Emission Feature in the Carina Nebula H II Region
Onaka, Takashi; Chan, Kin-Wing
We report the detection of a broad 22 µm emission feature in the Carina Nebula H II region by the Infrared Space Observatory (ISO) short-wavelength spectrometer. The feature shape is similar to that of the 22 µm emission feature of newly synthesized dust observed in the Cassiopeia A supernova remnant. This finding suggests that both of…