Search Publications
Near-Infrared Imaging of Mars from HST: Surface Reflectance, Photometric Properties, and Implications for MOLA Data
Crisp, David; Bell, James F.; Trauger, John T. +5 more
We report initial results from Hubble Space Telescope (HST) images of Mars obtained at a near-IR wavelength of 1042 nm between February 1995 and June 1997. The images provide the highest spatial resolution global near-IR measurements of Mars obtained to date. The data have been calibrated to radiance factor (I/F) to an absolute accuracy of 2 to 5%…
Chromatic Holography of the Sunspot Acoustic Environment
Braun, D. C.; Lindsey, C.
We use helioseismic holography to obtain seismic images of a sunspot and its local environment over the 3-8 mHz acoustic spectrum. We are particularly interested in the acoustic deficit brought about by strong acoustic absorption by the sunspot itself in the 3-4 mHz range and in the helioseismic character of the ``acoustic moat'' recently discover…
Globular clusters in NGC 5128
Côté, P.; Holland, S.; Hesser, J. E.
We used the Wide Field Planetary Camera 2 aboard the Hubble Space Telescope to search for globular clusters in the inner regions of the nearby giant elliptical galaxy
Evidence for the stratification of Fe in the photosphere of G191-B2B
Barstow, M. A.; Holberg, J. B.; Hubeny, I.
The presence of heavy elements in the atmospheres of the hottest H-rich DA white dwarfs has been the subject of considerable interest. While theoretical calculations can demonstrate that radiative forces, counteracting the effects of gravitational settling, can explain the detections of individual species, the predicted abundances do not accord we…
Jovian Stratospheric Hazes: The High Phase Angle View from Galileo
Rages, Kathy; Beebe, Reta; Senske, David
High phase angle Galileo images of Jupiter's limb reveal the presence of stratospheric hazes in the equatorial region (latitude 9°N) and the transition zone at the southern edge of the north polar region (60°N). During orbit E4, images were taken in both violet and near-IR continuum filters, effectively probing Jupiter's stratosphere at two differ…
North Polar Dust Storms in Early Spring on Mars
Wolff, Michael J.; James, Philip B.; Lee, Steven W. +1 more
Observations of Mars during 1996-1997 by the Hubble Space Telescope covered the entire spring season in the northern hemisphere of Mars, which was favorably positioned for viewing the north polar region. This paper reports observations of dust activity during this period. Local dust activity occurred near the edge of the subliming north polar cap …
Star Clusters in M33. III. The Youngest Population
Chandar, Rupali; Bianchi, Luciana; Ford, Holland C. +1 more
We investigate the properties of young (<=10^8 yr) M33 star clusters from the samples presented in the first two papers of this series using far-UV photometry. Previously, UBV colors were used to derive cluster ages, luminosities, and masses, assuming an extinction interpolated from neighboring stars. Fifteen of 44 clusters imaged in the Hubble…
IC 348 proper motion study from digitised Schmidt plates
Preibisch, T.; Zinnecker, H.; Meusinger, H. +6 more
A new proper motion study for about 1400 stars with R < 18 mag in a one square degree region around the young open cluster IC 348 based on Schmidt plates is presented. With an overall accuracy of about 3 mas/yr (2.5 mas/yr, respectively for all stars with R < 17 mag) we have obtained membership probabilities dividing our sample into three gr…
A very cold disc of dust around the G0V star HD 207129
Kessler, M. F.; Siebenmorgen, R.; Bouchet, P. +9 more
We present ISO observations made between 2.5 and 180 mu m of the nearby G0V dwarf HD 207129 taken as part of a large survey of nearby main-sequence stars in search of debris discs. HD 207129 emits radiation in excess of the photospheric flux density between at least 60 and 180 mu m. The infrared excess is explained by a disc of cold dust particles…
Emission lines of [O II] in the optical and ultraviolet spectra of planetary nebulae
Feibelman, W. A.; Keenan, F. P.; Hyung, S. +5 more
Recent R-matrix calculations of electron impact excitation rates in O II are used to calculate the emission-line ratio-ratio diagrams (R_1, R_2), (R_1, R_3) and (R_1, R_4), where R_1 = I(3729 A)/I(3726 A), R_2 = I(7320 A)/I(3726 + 3729 A), R_3 = I(7330 A)/I(3726 + 3729 A) and R_4 = I(2470 A)/I(3726 + 3729 A), for a range of electron temperatures (…