Search Publications
Kinematics of the HH 111 Jet from the Space Telescope Imaging Spectrograph
Garnavich, P. M.; Raga, A. C.; Noriega-Crespo, A. +4 more
We present a long-slit spectrum of the Herbig-Haro object HH 111, obtained with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. This spectrum has a spectral resolution of ~50 km s-1, so it gives a good picture of the kinematical properties of the observed object at very high angular resolution. We find that…
The Nature of Blinkers and the Solar Transition Region
Priest, E. R.; Hood, A. W.; Bewsher, D.
Solar plasma that exists at around 105 K, which has traditionally been referred to as the solar transition region, is probably in a dynamic and fibril state with a small filling factor. Its origin is as yet unknown, but we suggest that it may be produced primarily by one of five different physical mechanisms, namely: the heating of cool…
Associated Absorption Lines in the Radio-loud Quasar 3C 351: Far-Ultraviolet Echelle Spectroscopy from the Hubble Space Telescope
Kriss, G. A.; Green, R. F.; Kaiser, M. E. +3 more
As one of the most luminous radio-loud quasars showing intrinsic ultraviolet (UV) and X-ray absorption, 3C 351 provides a laboratory for studying the kinematics and physical conditions of such ionized absorbers. We present an analysis of the intrinsic absorption lines in the high-resolution (~7 km s-1) far-UV spectrum that was obtained …
High-Resolution Spectroscopy of G191-B2B in the Extreme-Ultraviolet
Culhane, J. L.; Barstow, M. A.; Brown, C. M. +14 more
We report a high-resolution (R=3000-4000) spectroscopic observation of the DA white dwarf G191-B2B in the extreme-ultraviolet band 220-245 Å. A low-density, ionized He component is clearly present along the line of sight, which if completely interstellar implies a He ionization fraction considerably higher than is typical of the local interstellar…
Modeling the radial variation of coronal streamer belts during sunspot ascending phase
Hoeksema, J. T.; Zhao, X. P.; Rich, N. B.
The coronal streamer belts and their radial variation between 2.5 and 20.0 solar radii in the ascending phase of the solar cycle can be well reproduced using the horizontal current-current sheet-source surface magnetic field model with the set of model parameters determined based on MDI and LASCO Carrington maps during 1996 minimum activity phase.
Spatially Resolved Far Ultraviolet Spectroscopy of the Jovian Aurora
Clarke, J. T.; Grodent, D.; Gérard, J. C. +1 more
Spatially resolved spectra in four 50-Å FUV spectral windows were obtained across the jovian aurora with the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope. Nearly simultaneous ultraviolet imaging makes it possible to correlate the intensity variations along the STIS slit with those observed in the images and to ch…
A Critical Examination of Hypernova Remnant Candidates in M101. II. NGC 5471B
Lai, Shih-Ping; Chu, You-Hua; Wang, Q. Daniel +2 more
NGC 5471B has been suggested to contain a hypernova because of its extraordinarily bright X-ray emission. To assess its true nature, we have obtained high-resolution images in continuum bands and nebular lines with the Hubble Space Telescope, and high-dispersion long-slit spectra with the Kitt Peak National Observatory 4 m echelle spectrograph. Th…
A 60 pc counter-rotating core in NGC 4621
Copin, Y.; Emsellem, E.; Wernli, F.
We present adaptive optics assisted OASIS integral field spectrography of the S0 galaxy NGC 4621. Two-dimensional stellar kinematical maps (mean velocity and dispersion) reveal the presence of a ~ 60 pc diameter counter-rotating core (CRC), the smallest observed to date. The OASIS data also suggests that the kinematic center of the CRC is slightly…
Total solar irradiance variations since 1978
Fröhlich, Claus
A composite record of solar total irradiance compiled from measurements made by five independent space-based radiometers since 1978 is the basis for an evaluation of the influence of solar activity on total solar irradiance. An empirical model that parameterizes the combined influences of dark sunspots and bright faculae features on solar irradian…
The Unusual Dynamics of Northern Dark Spots on Neptune
Baines, K. H.; Sromovsky, L. A.; Fry, P. M.
Hubble Space Telescope (HST) and ground-based observations of Neptune from 1991 to 2000 show that Neptune's northern Great Dark Spots (NGDS) remained remarkably stable in latitude and longitudinal drift rate, in marked contrast to the 1989 southern Great Dark Spot (GDS), which moved continuously equatorward during 1989 and dissipated unseen during…