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Metastable hydrogen absorption in ejecta close to η Carinae
Gull, T. R.; Johansson, S.; Hartman, H. +1 more
Spectroscopy with the high spatial resolution of the Hubble Space Telescope (HST) reveals narrow absorption in the hydrogen Balmer lines in spectra of Eta Carinae and the nearby nebular-scattered starlight. While hydrogen Balmer absorption lines are seen in stellar photospheres and winds, we are not aware of such being seen in galactic nebulae. Th…
ISO observations and models of galaxies with hidden broad line regions
Siebenmorgen, R.; Efstathiou, A.
We present ISO mid-infrared spectrophotometry and far-infrared photometry of galaxies with Hidden Broad Line Regions (HBLR). We also present radiative transfer models of their spectral energy distributions which enable us to separate the contributions from the dusty disc of the AGN and the dusty starbursts. We find that the combination of tapered …
Structure of visible and dark matter components in spiral galaxies at redshifts z = 0.5{-0.9}
Tamm, A.; Tenjes, P.
We have constructed self-consistent light and mass distribution models for four disk galaxies at redshifts z=0.48, 0.58, 0.81 and 0.88, using the HST archive WFPC2 observations (HDF-S, MDS, Groth Strip survey) and rotation curves measured by Vogt et al. ([CITE]) and Rigopoulou et al. ([CITE]). The models consist of three components: a bulge, a dis…
Search for the elusive optical counterpart of PSR J0537-6910 with the HST Advanced Camera for Surveys
Pulone, L.; Mignani, R. P.; Iannicola, G. +3 more
We present the results of deep, high-resolution, multi-band optical observations of the field of the young (∼ 5000 yr) 16 ms X-ray pulsar PSR J0537-6910 performed with the Advanced Camera for Surveys (ACS) aboard the Hubble Space Telescope (HST). Although a few new potential counterparts have been detected within or close to the revised Chandra X-…
Variability in Saturn's bow shock and magnetopause from Pioneer and Voyager: Probabilistic predictions and initial observations by Cassini
Russell, C. T.; Dougherty, M. K.; Neubauer, F. M. +2 more
Probability distributions for the location of the Saturnian bow shock and magnetopause have been derived by extrapolating observations of dynamic solar wind pressures to the position of Saturn's orbit. These observations are those made by the Pioneer 11, Voyager 1 and 2 spacecraft near Saturn's orbit and by the Ulysses spacecraft near its aphelion…
Hubble Space Telescope imaging polarimetry of Mars during the 2003 opposition
Kreslavsky, M.; Shkuratov, Yu.; Kaydash, V. +6 more
We report results of polarimetric imaging observations of Mars with the Hubble Space Telescope during the 2003 opposition. Through careful calibration, the observations with the ACS camera allow measurements of the polarization degree with an absolute accuracy better than 0.5% and detection of features with polarization degree contrast as small as…
Escape of Lyα Emission in the Starburst Galaxy Markarian 357: a Wind's Far Side
Keel, William C.
Hubble Space Telescope imaging and slitless spectroscopy are used to examine where the strong Lyα emission escapes from the interstellar medium in the starburst galaxy Mrk 357. An Hα image shows that the ionized gas is mostly in a global wind, rather than associated with the individual star-forming regions seen in the optical and UV continuum. The…
Orbital period variation in close binaries from radial velocity data and magnetic activity cycles. II. HR 1099
Lanza, A. F.; Frasca, A.
We studied orbital period changes in the non-eclipsing close binary HR 1099, one of the most bright members of the RS CVn class of magnetically active binary systems. Intermediate-resolution optical spectroscopy and IUE archive spectra were used to build radial-velocity curves yielding epochs of superior conjunction with an accuracy of 0.01 days. …
High-resolution extreme ultraviolet spectroscopy of G191-B2B: structure of the stellar photosphere and the surrounding interstellar medium
Dreizler, S.; Barstow, M. A.; Hubeny, I. +8 more
We have continued our detailed analysis of the high-resolution (R= 4000) spectroscopic observation of the DA white dwarf G191-B2B, obtained by the Joint Astrophysical Plasmadynamic Experiment (J-PEX) normal incidence sounding rocket-borne telescope, comparing the observed data with theoretical predictions for both homogeneous and stratified atmosp…
PFS-MEX observation of ices in the residual south polar cap of Mars
Piccioni, G.; Hansen, G.; Grassi, D. +10 more
The Mars Express spacecraft has a highly inclined orbit around Mars and so has been able to observe the south pole of Mars in illuminated conditions at the end of the southern summer ( L=330). Spectra from the planetary Fourier spectrometer (PFS) short wavelength (SW) channel were recorded over the permanent ice cap to study its composition in ter…