Search Publications
The Complex Kinematics of the Neutral Hydrogen Associated with I ZW 18
Salzer, John J.; Haynes, Martha P.; van Zee, Liese +1 more
We present the results of high velocity (1.3 km s^-1 channels) and high spatial (~5", or ~250 pc at the distance of I Zw 18) resolution H i synthesis observations of the blue compact dwarf galaxy I Zw 18 to investigate the link between its unique evolutionary history and the neutral gas distribution and kinematics. The H i distribution is extensiv…
Measuring the Sun's Eigenfrequencies from Velocity and Intensity Helioseismic Spectra: Asymmetrical Line Profile-fitting Formula
Kosovichev, A. G.; Nigam, R.
Solar eigenfrequencies are generally determined by fitting a Lorentzian to the spectral lines in the power spectrum. This assumes that the spectral line is symmetric. Recent observations from the Michelson Doppler Imager (MDI) on board the Solar and Heliospheric Observatory have indicated that the power spectra of p-modes show varying amounts of a…
Evidence for a 3 X 10^8 M_⊙ Black Hole in NGC 7052 from Hubble Space Telescope Observations of the Nuclear Gas Disk
van den Bosch, Frank C.; van der Marel, Roeland P.
We present a Hubble Space Telescope (HST) study of the nuclear region of the E4 radio galaxy NGC 7052, which has a nuclear disk of dust and gas. The Second Wide Field and Planetary Camera (WFPC2) was used to obtain B, V, and I broadband images and an Hα + [N II] narrowband image. The images yield the stellar surface brightness profile, the optical…
The Hubble Space Telescope Quasar Absorption Line Key Project. XIII. A Census of Absorption-Line Systems at Low Redshift
Turnshek, David A.; Schneider, Donald P.; Savage, Blair D. +9 more
We present a catalog of absorption lines obtained from the analysis of the ultraviolet spectra of 66 quasars. The data were acquired with the Faint Object Spectrograph of the Hubble Space Telescope (HST) as part of the Quasar Absorption Line Survey, a Key Project for the first four cycles of HST observations. This is the third of a series of catal…
Refining the Oort and Galactic constants
Merrifield, Michael R.; Olling, Rob P.
The local stellar kinematics of the Milky Way offer a useful tool for studying the rotation curve of the Galaxy. These kinematics - usually parametrized by the Oort constants AB - depend on the local gradient of the rotation curve as well as its absolute value (Theta_0), and the Sun's distance to the Galactic Centre (R_0). The density of interstel…
The Structure of the Prototype Bipolar Protoplanetary Nebula CRL 2688 (Egg Nebula): Broadband, Polarimetric, and H2 Line Imaging with NICMOS on the Hubble Space Telescope
Schneider, Glenn; Hines, Dean C.; Rieke, Marcia J. +5 more
High-resolution near-infrared (1.65-2.1 µm) images and 2 µm polarimetric images of the inner 19.5" × 19.3" region of the bipolar protoplanetary nebula CRL 2688, taken with the newly installed Near-Infrared Camera and Multiobject Spectrometer (NICMOS) aboard the Hubble Space Telescope (HST), are reported. The NICMOS images reveal a weal…
Evidence for water vapor in Titan's atmosphere from ISO/SWS data
de Graauw, Th.; Kessler, M. F.; Lellouch, E. +6 more
The infrared spectrum of Titan around 40 mu m was recorded in the grating mode of the Short Wavelength Spectrometer (SWS) of ISO, with a resolving power of about 1900. Two emission features appear at 43.9 and 39.4 mu m, where pure rotational water lines are expected. Line strengths are about 8 times the 1sigma statistical noise level. The H_2O ver…
Spheroid Luminosity and Mass Functions from Hubble Space Telescope Star Counts
Gould, Andrew; Bahcall, John N.; Flynn, Chris
We analyze 166 spheroid subdwarfs (6.5 < MV < 14.5) found in 53 fields observed with the Wide Field Planetary Camera on the Hubble Space Telescope. The fields cover 221 arcmin2 over a wide range of directions. The spheroid luminosity function (LF) is inconsistent at about the 3 σ level with the local spheroid LF of Dahn…
Coronal Composition above the Solar Equator and the North Pole as Determined from Spectra Acquired by the SUMER Instrument on SOHO
Schühle, U.; Feldman, U.; Laming, J. M. +1 more
Using spectra obtained by the SUMER instrument on the Solar and Heliospheric Observatory (SOHO) we have determined the composition of the bulk of the coronal plasma in the vicinity of the solar surface over a polar coronal hole and an equatorial region. Our measurements show that although low first ionization potential (FIP) elements are enriched …
HSTcolour-magnitude diagrams of six old globular clusters in the LMC
Suntzeff, N. B.; Walker, A. R.; Mateo, M. +4 more
We report on HST observations of six candidate old globular clusters in the Large Magellanic Cloud (LMC): NGC 1754, 1835, 1898, 1916, 2005 and 2019. Deep exposures with the F555W and F814W filters provide us with colour-magnitude diagrams that reach to an apparent magnitude in V of ~25, well below the main-sequence turn-off. These particular clust…