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Stellar radii of M giants
Schild, H.; Dumm, T.
We determine the stellar radii of the M giant stars in the Hipparcos catalogue3 that have a parallax measured to better than 20% accuracy. This is done with the help of a relation between a visual surface brightness parameter and the Cousins ( V - I) colour index, which we calibrate with M giants with published angular diameters. The ra…
Are Seyfert Narrow-Line Regions Powered by Radio Jets?
Dopita, Michael A.; Sutherland, Ralph S.; Tsvetanov, Zlatan I. +1 more
We argue that the narrow-line regions (NLRs) of Seyfert galaxies are powered by the transport of energy and momentum by the radio-emitting jets. This implies that the ratio of the radio power to jet energy flux is much smaller than is usually assumed for radio galaxies. This can be partially attributed to the smaller ages (~106 yr) of S…
The sun's shape and brightness
Kuhn, J. R.; Bush, R. I.; Scherrer, P. +1 more
We present satellite data that show that the sun's shape and temperature vary with latitude in an unexpectedly complex way. Although the solar oblateness shows no evidence of varying with the solar cycle, we find a significant hexadecapole shape term which may vary. We also see a variation of about 1.5 K in the surface temperature with latitude. B…
A Study of Nine High-Redshift Clusters of Galaxies. II. Photometry, Spectra, and Ages of Clusters 0023+0423 and 1604+4304
Postman, Marc; Lubin, Lori M.; Oke, J. B.
We present an extensive photometric and spectroscopic study of two high-redshift clusters of galaxies based on data obtained from the Keck 10 m telescopes and the Hubble Space Telescope. The clusters Cl 0023+0423 (z = 0.84) and Cl 1604+4304 (z = 0.90) are part of a multiwavelength program of Oke, Postman & Lubin to study nine candidate cluster…
X-ray and soft gamma-ray spectra of broad-line radio galaxies
Zdziarski, Andrzej A.; Madejski, Greg M.; Johnson, W. Neil +2 more
We study X-ray and soft gamma-ray spectral properties of nearby broad-line radio galaxies (BLRGs) using data from GingaASCA, OSSE and EXOSAT. The X-ray spectra are well fitted by an intrinsic power-law continuum with an energy index of alpha~0.7, moderately absorbed by a cold medium. In addition, the Ginga spectra show fluorescent Fe Kalpha lines …
Solar irradiances and radiances of UV and EUV lines during the minimum of sunspot activity in 1996
Wilhelm, K.; Curdt, W.; Lemaire, P. +6 more
Full Sun observations in UV and EUV emission lines were performed by SUMER (Solar Ultraviolet Measurements of Emitted Radiation) on SOHO (Solar and Heliospheric Observatory) in 1996. The radiometric pre-flight calibration of SUMER is traceable to a primary radiometric source standard - the electron storage ring BESSY. Based on this calibration, th…
Detailed study of FUV Jovian auroral features with the post-COSTAR HST faint object camera
Prangé, Renée; Rego, Daniel; Pallier, Laurent +3 more
A set of Hubble Space Telescope faint object camera images taken in the H2 bands near 1550 Å is used to infer the morphological properties of the steady state Jovian FUV aurorae. We focus on issues best addressed using the excellent spatial resolution available after correction of the spherical aberration, i.e., those related to high la…
Detection of Atomic Deuterium in the Upper Atmosphere of Mars
Krasnopolsky, Vladimir A.; Mumma, Michael J.; Randall Gladstone, G.
Photometry of Proxima Centauri and Barnard's Star Using Hubble Space Telescope Fine Guidance Sensor 3: A Search for Periodic Variations
Hemenway, P. D.; Jefferys, W. H.; Nelan, E. +10 more
We have observed Proxima Centauri and Barnard's star with the Hubble Space Telescope Fine Guidance Sensor 3. Proxima Cen exhibits small-amplitude, periodic photometric variations. Once several sources of systematic photometric error are corrected, we obtain 2 mmag internal photometric precision. We identify two distinct behavior modes over the pas…
Thermal Water Vapor Emission from Shocked Regions in Orion
Neufeld, David A.; Kaufman, Michael J.; Melnick, Gary J. +1 more
Using the Long Wavelength Spectrometer on board the Infrared Space Observatory, we have observed thermal water vapor emission from a roughly circular field of view approximately 75" in diameter centered on the Orion BN-KL region. The Fabry-Perot line strengths, line widths, and spectral line shifts observed in eight transitions between 71 and 125 …