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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…
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…
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…
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…
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…
Extreme-Ultraviolet Sunspot Plumes Observed with SOHO
Kjeldseth-Moe, O.; Haugan, S. V. H.; Brekke, P. +4 more
Bright EUV sunspot plumes have been observed in five out of nine sunspot regions with the Coronal Diagnostic Spectrometer on the Solar and Heliospheric Observatory. In the other four regions, the brightest line emissions may appear inside the sunspot but are mainly concentrated in small regions outside the sunspot areas. These results are in contr…
The Ages and Distances of Globular Clusters with the Luminosity Function Method: The Case of M5 and M55
Jimenez, Raul; Padoan, Paolo
We present new age and distance determinations for the Galactic globular clusters M55 and M5, using the luminosity function (LF) method of Padoan & Jimenez. Using the set of stellar tracks computed by Jimenez & MacDonald and taking into account a value of [α/Fe] = 0.4, we find an age of 12.5 +/- 1.0 Gyr for M55 and 10.6 +/- 0.8 Gyr for M5.…