Search Publications
Missions
Journals
Publication Years
ISOCAM Observations of the Comet P/Kopff Dust Trail
Reach, William T.; Boulanger, Francois; Sykes, Mark V. +3 more
We present the results of two scans through the dust trail of Comet P/Kopff made with ISOCAM on 26 March 1996. Positions behind the comet at mean anomalies of 0.5° and 1° less than the nucleus were imaged using the LW10 (IRAS Band 1, 12 µm) filter. The trail is clearly detected and appears to have varied since it was observed with the IRAS s…
Rest-frame variability of quasars and Seyfert galaxies in the ultraviolet: constraints on the discrete-event models.
Paltani, S.; Courvoisier, T. J. -L.
A study of the ultraviolet continuum variability (Paltani & Courvoisier, 1994A&A...291...74P) has shown that the relative variability of quasars and Seyfert galaxies decreases when the luminosity increases. The spectral information included in the IUE spectra allows us to study this dependence in the rest frame of the objects. The trend is…
Effects of Non-LTE Radiative Loss and Partial Ionization on the Structure of the Transition Region
Chae, J.; Yun, H. S.; Poland, A. I.
In this paper we address the question of how non-LTE radiative losses with partial ionization of hydrogen and helium affects the energetics and structure of the solar transition region. To accomplish this we have constructed theoretical models of a thin rigid magnetic flux tube with a steady material flow, which is embedded vertically in the solar…
Cassini/Huygens Science Instruments, Spacecraft, and Mission
Jaffe, Leonard D.; Herrell, Linda M.
Hubble Space Telescope Imaging of the Host Galaxies of Three X-Ray-selected BL Lacertae Objects
Yanny, Brian; Jannuzi, Buell T.; Impey, Chris
Hubble Space Telescope (HST) WFPC-2 I-band (F814W) images of three X-ray-selected BL Lacertae objects (MS 1221.8+2452, MS 1407.9+5954, and MS 2143.4+0704) reveal that each of these BL Lac objects is well centered in an extended nebulosity that is consistent in brightness and morphology with light from an elliptical galaxy at their previously repor…
The host to gamma-ray burst 970508: a distant dwarf galaxy?
Galama, T. J.; Bloom, J. S.; Kouveliotou, C. +6 more
If the optical transient to gamma-ray burst (GRB) 970508 is indeed associated with the 8 May burst and is connected with the z = 0.835 absorption system reported by Metzger et al. (1997) [Natur, 387, 879], then either the GRB originated from an intrinsically very faint galaxy (L ≲ 0.01L∗) or it occurred at a large distance from a host g…
Low-mass stars and star clusters in the dark Galactic halo
Kerins, E. J.
In a previous study it was proposed that the Galactic dark matter being detected by gravitational microlensing experiments such as MACHO may reside in a population of dim halo globular clusters comprising mostly or entirely low-mass stars just above the hydrogen-burning limit. It was shown that, for the case of a standard isothermal halo, the scen…
HST confirmation of the lensed quasar J03.13.
Surdej, J.; Claeskens, J. -F.; Remy, M. +4 more
In order to definitely prove the claim by Claeskens et al. (1996A&A...305L...9C) that J03.13 is a doubly imaged quasar, WFPC2 direct imaging and FOS spectroscopy of this compact system have been obtained with HST. These textbook case observations clearly show that J03.13 consists of two point-like images separated by 0.849"+/-0.001" with a mag…
The Spectrum of the Planetary Nebula NGC 6884
Feibelman, Walter A.; Hyung, Siek; Aller, Lawrence H.
The bright, compact, moderately high-excitation planetary nebula, NGC 6884 (Perek-Kohoutek 82 +07°1) has a rich spectrum promising good diagnostics and offering a good target for the Hamilton Echelle Spectrograph at Lick Observatory. We combine International Ultraviolet Explorer (IUE), near-UV, visual, and IR data to obtain N(ion)/N(H+)…
Mass and radius of the white dwarf in the binary V471 Tau from ORFEUS and HIPPARCOS observations.
Rauch, T.; Werner, K.
We present a model atmosphere analysis of the white dwarf component in the K2V/DA eclipsing binary system V471 Tau, based upon FUV spectra obtained by the ORFEUS satellite. This system is regarded as the prototype of a post-common envelope WD+MS binary and, hence, is of considerable importance for our understanding of close binary evolution. From …