Search Publications
First statistical analysis of 5000 mass spectra of cometary grains obtained by PUMA 1 (Vega 1) and PIA (Giotto) impact ionization mass spectrometers in the compressed modes
Langevin, Y.; Bertaux, J. -L.; Kissel, J. +1 more
Impact ionization mass spectrometers have been flown on board the space vehicles Giotto (instrument PIA), Vega 1 and Vega 2 (instruments PUMA 1 and 2). All three instruments obtained a large collection of mass spectra of individual cometary dust particles in the mass range 3×10-16 - 3×10-10g. Spectra from PUMA 2 are still bei…
X-Ray Sources in Regions of Star Formation. II. The Pre--Main-Sequence G Star HDE 283572
Roth, M.; Linsky, J. L.; Walter, F. M. +7 more
This paper reports the detection of HDE 283572, a ninth-magnitude G star 8 arcmin south of RY Tau, as a bright X-ray source. The observations reveal this object to be a fairly massive (about 2 solar masses) pre-main-sequence star associated with the Taurus-Auriga star formation complex. It exhibits few of the characteristics of the classical T Tau…
EXOSAT Observations of 4U 1705-44: Type I Bursts and Persistent Emission
Hasinger, G.; Gottwald, M.; Sztajno, M. +2 more
During four Exosat observations, the bright galactic X-ray source 4U 1705-44 exhibited persistent emission variations from 1.3 to 10.7 x 10 to the -9th ergs/sq cm per sec in the 1-20 keV band. Type I X-ray bursts have been detected from this source whose properties correlate with source intensity. The burst shape changed with increasing intensity …
Multiwavelength monitoring of the dwarf nova VW Hydri. III. IUE observations.
Verbunt, F.; Pringle, J. E.; Hassall, B. J. M. +2 more
IUE observations of VW Hyi were obtained between September and November 1984 during three ordinary outbursts, one superoutburst, and quiescence. Progressive fall in UV fluxes is noted during quiescence, and the UV flux lags behind the optical flux during the rise to outburst peak. Initially in the superoutburst, the fluxes rise to the level of an …
Spectroscopy of the Rapidly Rotating K Star HD 36705
Gustafsson, B.; Edvardsson, B.; Vilhu, O.
Spectroscopic observations of HD 36705 are reported. Values of 100 + or - 5 km/s and 29 + or - 2 km/s are derived for the v sin i and radial velocity, respectively. The central wavelength of the broad H-alpha emission varies as a function of rotation phase with an amplitude of 16 km/s and with the maximum redshift at the photometric minimum. Using…
Simultaneous Multifrequency Observations of the BL Lacertae Object Markarian 421
Koyama, K.; Matsuoka, M.; Kondo, Y. +26 more
Simultaneous multifrequency observations of the BL Lac object Mrk 421 covering radio through X-ray wavelengths were performed on two occasions separated by 5 weeks in January and March 1984, and each observation was coordinated for about 1 week. Composite multifrequency spectra of the central nonthermal component were obtained at the two epochs af…
The D/h Ratio in Water from Comet p/ Halley
Berthelier, J. J.; Eberhardt, P.; Krankowsky, D. +6 more
The neutral gas mass spectrometer on the Giotto spacecraft made neutral and ion composition measurements with a high mass resolution. From a preliminary evaluation of the ion data within the contact surface the authors obtain for the water in Halley an 18O abundance of 18O/16O = 0.0023±0.0006 and for the D/H ratio …
Correlation between Spectral State and Quasi-periodic Oscillation Parameters in GX 5-1
van Paradijs, J.; van der Klis, M.; Lewin, W. H. G. +3 more
In a series of seven Exosat observations, the bimodal spectral behavior and the quasi-periodic oscillation (QPO)/red noise properties of GX 5-1 show a strict correlation. In one of the two spectral states (characterized by a 'horizontal branch' in the hardness-intensity diagram), strong 20-40 Hz QPO and red noise below about 60 Hz were always pres…
IUE Observations of Hydrogen and Deuterium in the Local Interstellar Medium
Moos, H. W.; Murthy, J.; Linsky, J. L. +4 more
The authors present and analyze high-dispersion IUE observations of the interstellar hydrogen and deuterium Lyα absorption profiles toward the late-type stars ɛ Eri (3.3 pc), Procyon (3.5 pc), Altair (5.1 pc), Capella (13.2 pc), and HR 1099 (33 pc). They derive values for the density nH I, the velocity dispersion bH I, the bu…
Ultraviolet Observations by the IUE of 31 Clusters of the Large Magellanic Cloud
Cassatella, A.; Geyer, E. H.; Barbero, J.
Ultraviolet observations of 31 star clusters of the Large Magellanic Cloud obtained by the International Ultraviolet Explorer are presented. The clusters, mostly globular, span the range of ages from about 10 to the 7th to 10 to the 10th yr. The sample includes several young globular clusters, which have no counterpart in the Galaxy. The paper is …