Search Publications
Missions
Journals
Publication Years
The EUV Spectrum of Sunspot Plumes Observed by SUMER on SOHO
Dwivedi, B. N.; Curdt, W.; Feldman, U.
We present results from sunspot observations obtained by SUMER on SOHO. In sunspot plumes the EUV spectrum differs from the quiet Sun; continua are observed with different slopes and intensities; emission lines from molecular hydrogen and many unidentified species indicate unique plasma conditions above sunspots. Sunspot plumes are sites of system…
Search for Proton Aurora and Ambient Hydrogen on Io
Trafton, L. M.
A search was conducted using the Hubble Space Telescope (HST) Goddard High Resolution Spectrograph (GHRS) in 1994 August for Iogenic H Lyα emission predicted from electron capture by precipitating trapped magnetospheric protons. The Doppler-shifted diffusely reflected solar Lyα component was detected in the combined high-resolution spectra, partly…
IUE Spectra of the Seyfert 1 Galaxies Mrk 335 and NGC 4051
Hyung, Siek; Kim, Hyouk; Lee, Woo Baik +3 more
The international ultraviolet explorer (IUE) spectra of a low dispersion ~6 A, have been investigated for two Seyfert 1 galaxies, Mrk 335 and NGC 4051, well known for the line variability. The electron densities of broad line region (BLR) of these variable Seyfert 1 galaxies have been derived, which showed a non-linear abrupt variation from 1e+8 t…
The ISO-SWS detectors: Performance trends and space radiation effects
Heras, A. M.; Morris, P.; Feuchtgruber, H. +6 more
We present a trend analysis of the ISO-SWS detector performance and a study of the space radiation effects on the SWS detectors. In particular, dark currents, dark current noise and detector responses have been checked as a function of time through the mission and as a function of time in a revolution. The results show that these parameters were s…
A Search for Warm Neutral Gas Associated with the Giant HII Region NGC 604
Beckman, J.; Gómez de Castro, A. I.; Sanz, L.
The characteristics of the halo gas and its interaction with the galactic disk in spiral galaxies are poorly known; this is particularly true for the warm neutral gas associated with HVCs and galactic chimneys. The detection of absorption features such as the NaI D or the CaII (H,K)lines is instrumental to study its detailed physical properties bu…
Magnitudes absolues des étoiles standards MK des types G à M à partir des parallaxes Hipparcos. The absolute magnitudes of the G to M type MK standards from the Hipparcos parallaxes
Jaschek, C.; Ginestet, N.; Carquillat, J. M.
We analyse a sample of about 500 MK standards of cool spectral types (G to M) for to compare the visual absolute magnitudes obtained from both Hipparcos data and Schmidt-Kaler calibrations. Our purpose is to validate our spectroscopic work \cite[(Ginestet et al. 1997, 1999)]{G97} on stars with composite spectra with the help of Hipparcos data. Con…
Microwave Observation of Eruptive Solar Events with and without Flare Activity
Shibasaki, K.; Hori, K.; Koshiishi, H. +2 more
We present microwave (17 GHz) observations of eruptive activity in four solar coronal events with the Nobeyama Radioheliograph. These are weak events occurring at or near the solar limb associated with several types of activity: polar crown activity, prominence eruptions, and arcade flares. The morphological evolutions of the microwave sources in …
A study of opacity in SOHO-SUMER and SOHO-CDS spectral observations. II. Atmospheric structure at the solar limb
Fischbacher, G. A.; Loch, S. D.; Summers, H. P.
To model the EUV emission from solar plasma at transition region temperatures it is necessary to take account of both the structure and dynamics of the plasma and the effects of opacity which radiatively couple different points within the plasma. Simple escape probability techniques exist which avoid the need for a full solution of the radiative t…
Comment on ``Bulk flows of hot plasma in the Jovian magnetosphere: A model of anisotropic fluxes of energetic ions'' by S. E. Hawkins III, A. F. Cheng, and L. J. Lanzerotti
Simnett, G. M.; Desai, M. I.
Abstract Available from AGU
Hubble Space Telescope Observations of the Shocks in Supernova Remnant SN 1987A
Michael, Eli
We present observations of supernova remnant SN 1987A made with the Hubble Space Telescope. The bright spot previously observed on the inner circumstellar ring by the Wide Field/Planetary Camera at a position angle ~31deg has brightened by nearly a factor of 2 in seven months. Space Telescope Imaging Spectrograph (STIS) spectra confirm …