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The 0623+71 Bow Shock Nebula
Feibelman, W. A.; Hollis, J. M.; Wagner, R. M. +1 more
Deep radio continuum and deep narrow-band optical emission-line images showing the cataclysmic variable 0623 + 71 engulfed in a bow shock morphology are presented. The limb-brightened H-alpha, forbidden N II and 6 cm radio continuum emission regions define the global nebular morphology, extending to much greater spatial distances than the apex-con…
Detection of a Proton Beam during the Impulsive Phase of a Stellar Flare
Robinson, Richard D.; Shore, Steven N.; Woodgate, Bruce E. +2 more
A transient event consistent with the predicted temporal and spectral signatures of an energetic proton beam was detected in the impulsive phase of a small flare on the red dwarf star AU Microscopii. It consisted of a prominent increase in the flux in the red wing of Lyman-alpha near 1223 A, simultaneously with the peak of a flare observed in the …
The origin of complex organic ions in the coma of Comet Halley
Reme, H.; Korth, A.; Lin, R. P. +3 more
Heavy ion mass spectra were obtained in the inner coma of Comet Halley by the Giotto-PICCA instrument. Outside the cometary ionopause, where ≳2000 K ion temperatures limited the effective mass resolution to 3 amu, the spectra exhibit a series of distinct mass groups that are separated by a constant ≈ 15 amu and extend to at least 120 amu. We show …
The FAST HIPPARCOS Data Reduction Consortium: Overview of the Adopted Reduction Software
Badiali, M.; Cardini, D.; Emanuele, A. +38 more
This paper gives the main features of the data analysis methods adopted by FAST in the calibration and processing of the Hipparcos data. The structure of the data reduction software is described and the actual processing and evaluation is presented.
The Identification of Highly Ionized Metal Species in the Hot DA1 White Dwarf G191-B2B with the Hubble Space Telescope Faint Object Spectrograph
Sion, Edward M.; Bohlin, Ralph C.; Tweedy, Richard W. +1 more
On the Certification of AM Canum Venaticorum as a Cataclysmic Variable
Halpern, Jules P.; Raymond, John C.; Patterson, Joseph +1 more
The evidence that the peculiar faint blue star AM CVn (= HZ 29) is an ultrashort-period cataclysmic binary is reexamined. The existence of at least two noncommensurate short periods in the light curve, plus the recent discovery of the class of pulsating DB white dwarfs, suggests a need for reappraisal of the binary star model. New photometry and s…
The Quantative Assessment of UV Extinction Derived From IUE Data of Giants and Supergiants
Sembach, Kenneth R.; Cardelli, Jason A.; Mathis, John S.
It is shown here that the UV interstellar extinction towards hot luminous stars can be determined as accurately as for hot main-sequence stars. An atlas of IUE dereddened fluxes is presented for 13 lightly reddened stars within the 1160-3125 A range. The fluxes of these stars how absorption line strengths that allow a rather accurate determination…
Gravitational Lensing of Quasars as Seen by the Hubble Space Telescope Snapshot Survey
Maoz, D.; Lahav, O.; Schneider, D. P. +4 more
As part of the ongoing HST Snapshot Survey, 152 additional high- luminosity z > 1 quasars were observed, bringing the total to 184 quasars. Each exposure was searched for evidence of gravitational lensing. Only one quasar among those observed, 1208+1011, is a candidate lens system with subarcsecond image separation. Six other quasars have point…
Chromospheric heating in late-type dwarfs : acoustic or magnetic ?
Doyle, J. G.; Mathioudakis, M.
Mg II h and k fluxes for 69 K and 88 M dwarfs have been analyzed. An empirical lower limit is found in the Mg II flux, extended down to the latest spectral types. Based on the data presented here it is the magnetic component that dominates the emission from the atmosphere of cool dwarfs, especially the M dwarfs. It, however, coexists with an acous…
New Calibrators for the Cepheid Period-Luminosity Relation
Evans, Nancy R.
IUE spectra of six Cepheids have been used to determine their absolute magnitudes from the spectral types of their binary companions. The stars observed are U Aql, V659 Cen, Y Lac, S Nor, V350 Sgr, and V636 Sco. The absolute magnitude for V659 Cen is more uncertain than for the others because its reddening is poorly determined and the spectral typ…