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ISOPHOT Maps of NGC 6946 in the range λ 60-200µm.
Helou, G.; Lemke, D.; Gabriel, C. +7 more
We present maps of NGC 6946 at λ 61 and 205µm as well as scans through the galaxy at these and at 8 intermediate wavelengths. The bulk of the FIR luminosity arises from a diffuse disk component which extends beyond the 25mag/arcsec^2^ B isophote to at least the radius corresponding to the sensitivity limit. A FIR emission counterpart to the …
High-Velocity Gas in GHRS Spectra of Three OB Stars
York, D. G.; Welty, D. E.; Lauroesch, J. T. +4 more
In Hubble Space Telescope (HST) GHRS spectra of the B1 V star 23 Ori, we observed interstellar absorption lines of C II, C 11*, Mg II, Al II, Al III, Si II, Si III, and S II at a heliocentric radial velocity of about -100 km s-1. Lines of N I, O I, and Fe II that normally are strongly saturated in low-velocity interstellar ga…
Thermal anisotropies in the solar wind: Evidence of heating by interstellar pickup ions?
Phillips, John L.; Richardson, John D.; Smith, Charles W. +1 more
A recent paper by Gray et al. [1996] shows that the Alfvén ion cyclotron instability is generated by newly created pickup ions and heats the thermal solar wind protons in the direction perpendicular to the magnetic field. This instability operates most effectively in regions where the plasma β is low, so this mechanism predicts that the ratio of t…
Accretion torques in the transient X-ray pulsar EXO2030+375.
Parmar, A. N.; Verbunt, F.; Wilson, R. B. +4 more
In 1985 May - October, EXOSAT observed two outbursts from the previously unknown accreting X-ray pulsar EXO2030+375. Using the orbital solution derived by the BATSE experiment on CGRO, the behavior of the pulse period variations can now be studied with much less ambiguity than was possible based on the EXOSAT observations alone. There is little ev…
The ROSAT-PSPC Spectrum of Bright Low-z Quasars
Molendi, S.; Ulrich-Demoulin, M. -H.
We present and discuss ROSAT Position Sensitive Proportional Counter (PSPC) spectra of seven bright low-redshift quasars obtained during pointed observations, including in the discussion the results previously obtained on the quasar PG 1116+215. Several pointed observations are available for two quasars. In two of our objects the count rate varied…
PU Vulpeculae: an eclipsing symbiotic nova.
Vogel, M.; Nussbaumer, H.
A series of IUE observation from 1992 to 1995 has definitely established PU Vul as an eclipsing binary. The outburst of this symbiotic nova began in 1977. An extended fading in 1980 gave rise to various interpretations, the eclipse scenario being one of them, dust formation being another. From AFOEV and AAVSO observations we find a period of 4900+…
On the width of the theoretical lower main sequence. Consequences for the determination of the {DELTA}Y/{DELTA}Z ratio in the solar neighbourhood.
Baglin, A.; Lebreton, Y.; Fernandes, J.
We discuss the relation between the main sequence thickness and chemical composition variations. With the help of theoretical zero-age main sequence models between 0.7 and 1.0Msun_, computed with an advanced physical description of the stellar interiors, in a range of metallicities typical from Population I stars (0.008<=Z<=0.034)…
Jovian Tropospheric Features—Wind Field, Morphology, and Motion of Long-Lived Systems
Simon, Amy A.; Beebe, Reta F.
A map spanning 360° of longitude and +5° to -65° latitude has been constructed from Hubble Space Telescope SL-9 Campaign F410M images obtained on July 23, 1994 with the WFPC2 in PC and WF mode. For comparison, a map spanning +65° to -65° has been generated from WFPC2 PC observations on February 17, 1995. Because the WFPC2 data has the highest spat…
The remarkable Herbig AE star V 351 Orionis=HD 38238.
The, P. S.; de Winter, D.; van den Ancker, M. E.
The photometric behaviour of the irregular variable Herbig Ae star V 351 Ori was investigated combining data from the literature with new photometric data in the Stroemgren system. It is shown that this enigmatic object changed its photometric behaviour from that of a Herbig Ae star with strong photometric variations, due to extinction by circumst…
Sleuthing the Dynamo: Hubble Space Telescope Faint Object Spectrograph Observations of Solar-Type Dwarfs in Young Galactic Clusters
Ayres, Thomas R.; Brown, Alexander; Simon, Theodore +3 more
We have used the Faint Object Spectrograph of the Hubble Space Telescope to record the ultraviolet emissions of solar-type [(B - V)0 ∼0.6 mag] dwarf stars in young galactic clusters: five in the Hyades (t 600 Myr); three in the Pleiades (t ∼ 70 Myr); and two in αPersei (t ∼ 50 Myr). Despite high levels of scattered light in the G130H (1…