Search Publications
Photoelectric Heating and [C II] Cooling of High Galactic Latitude Translucent Clouds
Reach, William T.; Ingalls, James G.; Bania, T. M.
The (2P3/2-->2P1/2) transition of singly ionized carbon, [C II], is the primary coolant of diffuse interstellar gas. We describe observations of [C II] emission toward nine high Galactic latitude translucent molecular clouds, made with the long-wavelength spectrometer on board the Infrared Space Obser…
The Infrared Emission Features in the Spectrum of the Wolf-Rayet star WR 48a
Tielens, A. G. G. M.; Peeters, E.; Chiar, J. E.
We present the first detection of unidentified infrared (UIR) emission features at ~6.4 and 7.9 µm in the spectrum of the dusty WC8 Wolf-Rayet star WR 48a. Based on the H-deficient nature of WC stars, we attribute the emission features to large carbonaceous molecules or amorphous carbon dust grains in the circumstellar environment of WR 48a.…
Runaway Fragmentation of Sungrazing Comets Observed with the Solar and Heliospheric Observatory
Sekanina, Zdenek
The observed clustering of the Solar and Heliospheric Observatory (SOHO) sungrazing comets is a product of runaway fragmentation that occurs throughout their orbits about the Sun. Since the sungrazers in tight pairs occasionally appear simultaneously in the field of view of the SOHO coronagraphs, their offsets can be used to determine their separa…
High-Resolution Measurements of Intersystem Bands of Carbon Monoxide toward X Persei
Federman, S. R.; Lambert, David L.; Sheffer, Yaron
In an echelle spectrum of X Per acquired with the Space Telescope Imaging Spectrograph, we have identified individual rotational lines of 11 triplet-singlet (intersystem) absorption bands of 12CO. Four bands provide first detections for interstellar clouds. From a comparison with the ζ Oph sight line, we find that X Per is obscured by a…
Solar Particle Event with Exceptionally High 3He Enhancement in the Energy Range up to 50 MeV Nucleon-1
Torsti, J.; Kaiser, M. L.; Kocharov, L. +3 more
We have surveyed the 3He-rich solar particle events in the energy range of greater than 15 MeV nucleon-1 observed with the energetic particle instrument ERNE (the Energetic and Relativistic Nuclei and Electron experiment) on board the Solar and Heliospheric Observatory during 1999-2000. The survey reveals the exceptional even…
What Is Happening at Spectral Type F5 in Hyades F Stars?
Carpenter, Kenneth; Robinson, Richard; Böhm-Vitense, Erika +1 more
Aiming at a better understanding of the mechanisms heating the chromospheres, transition regions, and coronae of cool stars, we study ultraviolet, low-resolution Hubble Space Telescope/Space Telescope Imaging Spectrograph spectra of Hyades main-sequence F stars. We study the B-V dependence(s) of the chromospheric and transition layer emission line…
Discovery of an Extremely Red Object in the Field of HD 155826
Djorgovski, S. G.; Christian, D. J.; Gorjian, V. +7 more
We have discovered an extremely red object, LSF 1, located 7" southwest (P.A. 217°) of the bright spectroscopic binary system HD 155826. Originally reported by IRAS as one source detected at 12-60 µm, and found as a single 6-25 µm source of similar flux in the Midcourse Space Experiment Galactic plane survey, two bright point sources w…
A Uniform Analysis of the Lyα Forest at z = 0-5. IV. The Clustering and Evolution of Clouds at z <= 1.7
Bechtold, Jill; Dobrzycki, Adam; Scott, Jennifer +1 more
We present results on the evolution and clustering of Lyα lines at low redshift as part of our series ``A Uniform Analysis of the Lyα Forest at z=0-5.'' The sample analyzed in this paper contains 1298 Lyα absorption lines from 165 quasar spectra mined from the archives of the Faint Object Spectrograph on the Hubble Space Telescope (HST). Our sampl…
The Search for Intergalactic Hydrogen Clouds in Voids
Manning, Curtis V.
I present the results of a search for intergalactic hydrogen clouds in voids. Clouds are detected by their H I Lyα absorption lines in the Hubble Space Telescope spectra of low-redshift active galactic nuclei. The parameter with which the environments of clouds are characterized is the tidal field, for this places a lower limit on the cloud mass d…
The Capella Giants and Coronal Evolution across the Hertzsprung Gap
Young, P. R.; Kriss, G. A.; Dupree, A. K. +5 more
We present an analysis of the coronal line Fe XXI λ1354 observed in medium-resolution Hubble Space Telescope/Space Telescope Imaging Spectrograph echelle spectra of Capella obtained on 1999 September 12. These data were collected in support of a multiwavelength spectroscopic campaign designed to provide detailed temperature and density diagnostics…