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The Lower Main Sequence of ω Centauri from Deep Hubble Space Telescope NICMOS Near-Infrared Observations
Paresce, Francesco; De Marchi, Guido; Pulone, Luigi +1 more
A 20" × 20" field located ~7' from the center of the massive galactic globular cluster ω Centauri (NGC 5139) was observed by the NIC2 camera of the Near-Infrared Camera and Multiobject Spectrometer on board the Hubble Space Telescope (HST) through the F110W and F160W broadband filters centered at 1.1 and 1.6 µm for a total of 3000 and 4000 s…
Joint Nancay Radioheliograph and LASCO Observations of Coronal Mass Ejections - II. The 9 July 1996 Event
Llebaria, A.; Michels, D. J.; Schwenn, R. +10 more
The development of a coronal mass ejection on 9 July 1996 has been analyzed by comparing the observations of the LASCO/SOHO coronagraphs with those of the Nancay radioheliograph. The spatial and temporal evolution of the associated radioburst is complex and involves a long-duration continuum. The analysis of the time sequence of the radio continuu…
Resolving the Intrinsic C IV Absorption in the Seyfert 1 Galaxy NGC 3516
Mushotzky, Richard F.; Crenshaw, D. Michael; Maran, Stephen P.
We observed the Seyfert 1 galaxy NGC 3516 with the Goddard High Resolution Spectrograph on the Hubble Space Telescope, and obtained UV spectra at a resolution of λ/Δλ ~ 20,000 in the redshifted C IV λ1549 region. The intrinsic C IV absorption in the core of the broad emission line is resolved for the first time into four distinct kinematic compone…
Ultraviolet Spectral Dating of Stars and Galaxies
Beck, T.; Bohlin, R. C.; Heap, S. R. +17 more
An echelle spectrogram (R = 30,000) of the 2300-3100 Å region in the ultraviolet spectrum of the F8 V star 9 Comae is presented. The observation is used to calibrate features in the mid-ultraviolet spectra of similar stars according to age and metal content. In particular, the spectral break at 2640 Å is interpreted using the spectral synthesis co…
The 3-D Plasma Distribution Function Analyzers With Time-of-Flight Mass Discrimination for Cluster, FAST, and Equator-S
Balsiger, H.; Klecker, B.; Kistler, L. M. +39 more
A similar time-of-flight plasma analyzer system will be flown as CODIF (COmposition and DIstribution Function analyzer) on the four Cluster spacecraft, as ESIC (Equator-S Ion Composition instrument) on Equator-S, and as TEAMS (Time-of-flight Energy Angle Mass Spectrograph) on FAST. These instruments will for the first time allow the 3-dimensional …
Hubble Space Telescope Ultraviolet Imaging and High-Resolution Spectroscopy of Water Photodissociation Products in Comet Hyakutake (C/1996 B2)
Feldman, P. D.; Keller, H. U.; Combi, M. R. +3 more
Comet Hyakutake (C/1996 B2) provided a target of opportunity for performing a systematic study of water photodissociation products in which we obtained data from three instruments on the Hubble Space Telescope (HST). The HST Goddard High Resolution Spectrograph (GHRS) was used to measure the line profile of hydrogen Lyα (H Lyα) at six locations ar…
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 …