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Temperature Variations and N/O in the Orion Nebula from HST Observations
Martin, P. G.; Dufour, R. J.; Ferland, G. J. +4 more
Using the Goddard High Resolution Spectrograph (GHRS) and the Faint Object Spectrograph (FOS) on the Hubble Space Telescope, we measured the flux of the N II] (2s2p3 5S2 --> 2s22p2 3P2,1) lines at λvac = 2143.45, 2139.68 Å in the Orion Nebula--the first dete…
Doppler redistribution of anisotropic radiation and resonance polarization in moving scattering media. I. Theory revisited in the density matrix formalism
Bommier, V.; Feautrier, N.; Sahal-Brechot, S.
Under the light of recent developments of the theory of matter-radiation interaction in the presence of magnetic field applied to non-LTE spectropolarimetry in astrophysics, we have revisited the theory of anisotropic resonance line scattering in moving media by means of the density-matrix formulation. This has led us to present a theoretical meth…
Infrared mapping of the dust disc around VEGA
Walker, H. J.; Klaas, U.; Heinrichsen, I.
ISOPHOT has been used to perform high-resolution 60-µm scans of Vega, and these have been compared with those from gammaDra, to obtain a Gaussian width of 22+/-2 arcsec. The dust disc around Vega has been mapped, resolving it at 60 and 90 µm with ISOPHOT. At 90 µm a Gaussian width of 36+/-3 arsec has been derived. In addition, mu…
Are solar acoustic modes correlated?
Roca Cortes, T.; Ulrich, R. K.; Boumier, P. +7 more
We have studied the statistical properties of the energy of individual acoustic modes, extracted from 310 days of GOLF data near the solar minimum. The exponential distribution of the energy of each mode is clearly seen. The modes are found to be uncorrelated with a partial 0.6% accuracy, thus supporting the hypothesis of stochastic excitation by …
Iron freeze-in temperatures measured by SOHO/CELIAS/CTOF
Livi, S.; Hsieh, K. C.; Wurz, P. +26 more
The CELIAS particle experiment on SOHO contains the Charge Time Of Flight (CTOF) mass spectrometer which measures the ionic and elemental composition of minor ions in the solar wind. In this paper we present iron freeze-in temperatures derived with a time resolution of 5 min. They indicate that some of the filamentary structures of the inner coron…
Calibration of the SERTS-95 Spectrograph from Iron Line Intensity Ratios
Brosius, Jeffrey W.; Thomas, Roger J.; Davila, Joseph M.
Goddard Space Flight Center's Solar EUV Rocket Telescope and Spectrograph was flown on 1995 May 15 (SERTS-95), carrying a multilayer-coated toroidal diffraction grating which enhanced the instrumental sensitivity within its second-order wave band (170-225 Å). Spectra and spectroheliograms of NOAA Active Region 7870 (N09/W22) were obtained in this …
Discovery of a Very Low Mass Binary with the Hubble Space TelescopeNear-Infrared Camera and Multiobject Spectrometer
Rebolo, R.; Zapatero Osorio, M. R.; Martín, E. L. +7 more
Hubble Space Telescope Near-Infrared Camera and Multiobject Spectrometer (NICMOS) observations of six brown dwarf candidates in the Pleiades open cluster are presented. One of them, namely CFHT-Pl-18, is clearly resolved as a binary with an angular separation of 0.33". The very low density of contaminating background stars in our images and the ph…
HST/FOC observations confirm the presence of a spectral feature in the optical spectrum of Geminga
Caraveo, P. A.; Bignami, G. F.; Mignani, R. P.
New optical and near-UV HST observations of Geminga are presented. When compared with previous ground-based and HST imaging, the data confirm and better define the presence of an emission feature centered at ~ 6,000 Angstroms and superimposed on the thermal continuum best fitting the extreme-UV/soft X-ray data. This feature may be interpreted in t…
Ultraviolet and Optical Spectroscopy Of AL Comae 1 Year After Superoutburst
Szkody, Paula; Howell, Steve B.; Sion, Edward M. +3 more
We present Hubble Space Telescope (HST) ultraviolet spectra of AL Com obtained with the Faint Object Spectrograph (FOS) during four epochs 10-14 months following its 1995 April superoutburst. During our 1996 observations, the continuum fluxes underwent a slow decline of 20%, while the spectrum showed Lyα and Si II absorption features indicative of…
Observational evidence for coronal mass injection by ``evaporation" of spicular plasma
Glassmeier, K. -H.; Wilhelm, K.; Schroeder, K. -P. +1 more
Despite being a common feature of the solar chromosphere, spicules are still a poorly understood phenomenon. Not much is known about their impact on the physics of the transition region and corona, for which spicules are believed to be the dominant mechanism for mass injection. We recently observed the spatial plasma structure of polar spicules in…