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Alfvén waves, alpha particles, and pickup ions in the solar wind
Smith, E. J.; Goldstein, B. E.; Neugebauer, M.
Past studies of the properties of Alfvén waves in the solar wind have indicated that (1) the amplitude of the velocity fluctuations is almost always smaller than expected on the basis of the amplitude of the field fluctuations, even when the anisotropy of the plasma is taken into account, and (2) the alpha particles often do not participate in the…
Variation of fractional electron density fluctuations inside 40 Ro observed by Ulysses ranging measurements
Bird, M. K.; Woo, Richard; Armstrong, J. W. +1 more
The first measurements of fractional electron density fluctuations δne/ne, where δne is rms electron density fluctuation and ne is the mean electron density, have been carried out inside 40 Ro using 1991 Ulysses dual-frequency S- and X-band (13 and 3.6 cm) ranging (time delay) measurements. In…
Hubble Space Telescope Imaging of Neptune's Cloud Structure in 1994
Hammel, H. B.; Lockwood, G. W.; Barnet, C. D. +1 more
Images of Neptune taken at six wavelengths with the Hubble Space Telescope in October and November 1994 revealed several atmospheric features not present at the time of the Voyager spacecraft encounter in 1989. Furthermore, the largest feature seen in 1989, the Great Dark Spot, was gone. A dark spot of comparable size had appeared in the northern …
High-Velocity, High-Excitation Neutral Carbon in a Cloud in the VELA Supernova Remnant
Jenkins, Edward B.; Wallerstein, George
HD 72089 is situated behind the Vela supernova remnant, and the interstellar absorption lines in the spectrum of this star are remarkable for two reasons. First, there are six distinct velocity components that span the (heliocentric) velocity range -60 to +121 km/s in the lines of Na I and Ca II. Second, two of the components at high velocity, one…
Globular Clusters in Coma Galaxy NGC 4881
Holtzman, J. A.; Faber, S. M.; Grillmair, C. J. +8 more
We report HST-WFPC2 observations of the bright E0 galaxy NGC 4881, located about 18' north of the center of the Coma Cluster. Counts of globular clusters (GCs) were made both within the PC 1(f/28) frame and within the three WFC (f/13) frames. Attention was focused mainly on the PC1 data, in which faint GCs could be distinguished from noise spikes …
Proof of a fast wind in the symbiotic nova AG Pegasi.
Schmutz, W.; Vogel, M.; Nussbaumer, H.
Hubble Space Telescope observations of the symbiotic nova AG Peg reveal a P Cygni profile in N V λl240. This proves that the hot compact object in the binary system loses material through a fast wind. High resolution spectra allow to discern three different emission regions: the wind from the hot compact star, a nebular emission region of relative…
Results of the Ulysses fast latitude scan: Magnetic field observations
Balogh, A.; Forsyth, R. J.; Burton, M. E. +2 more
The rapid crossing of the solar equatorial region by Ulysses as it returned from the south pole resulted in 7 crossings of the heliospheric current sheet between 10°S and 20°N and 10 distinct solar wind interaction regions between 18°S and 22°N. Both the extent of the current sheet and the latitude interval containing the interaction regions are a…
Fading and variations in the spectrum of the central star of the very young planetary nebula SAO 244567 (Hen 1357).
Pottasch, S. R.; de Martino, D.; Parthasarathy, M. +6 more
The optical spectrum of SAO 244567 obtained in 1971 shows that it was a post-AGB B1 or B2 supergiant at that time. It has turned into a planetary nebula (PN ) within the last 20 years. The IUE ultraviolet spectra obtained during the last seven years show that the central star is rapidly evolving. It is found that the central star of this young PN …
Structural Parameters of Faint Galaxies from Prerefurbishment Hubble Space Telescope Medium Deep Survey Observations
Im, M.; Griffiths, R. E.; Casertano, S. +4 more
We present a statistical study of the properties of faint galaxies from a large catalog of about 13,500 objects found in 112 random fields observed with the Hubble Space Telescope Wide Field Camera before refurbishment. The majority of the objects are faint galaxies with 18 < I < 25 mag. For each object we determine half-light radius, magnit…
Ultra-high excitation features in hot white dwarfs: A DAO and three DO stars discovered by the Hamburg-Schmidt survey.
Dreizler, S.; Heber, U.; Napiwotzki, R. +1 more
We report on the discovery of four hot white dwarfs, one DAO (HS2115+1148) and three DO (HS0158+2335, HS 0727+6003 and HS 2027+0651). The spectra of these stars exhibit shallow metal absorption lines from ultrahighly excited ionization stages (C V, C VI/N VI, N VII/O VII, O VIII, Ne IX, Ne X) with ionization energies ranging from 392eV to 1362eV. …