Hubble Space Telescope far-ultraviolet imaging of M31, M32, and NGC 205

1995 ◽  
Vol 438 ◽  
pp. 680 ◽  
Author(s):  
F. Bertola ◽  
A. Bressan ◽  
D. Burstein ◽  
L. M. Buson ◽  
C. Chiosi ◽  
...  
2004 ◽  
Vol 614 (1) ◽  
pp. L61-L64 ◽  
Author(s):  
Edward M. Sion ◽  
F. H. Cheng ◽  
Boris T. Gänsicke ◽  
Paula Szkody

1991 ◽  
Vol 377 ◽  
pp. L1 ◽  
Author(s):  
E. A. Beaver ◽  
E. M. Burbidge ◽  
Ross D. Cohen ◽  
Vesa T. Junkkarinen ◽  
Ronald W. Lyons ◽  
...  

2021 ◽  
Author(s):  
Lorenz Roth ◽  
Nickolay Ivchenko ◽  
Randy Gladstone ◽  
Joachim Saur ◽  
Denis Grodent ◽  
...  

<p>Ganymede’s tenuous atmosphere is produced by charged particle sputtering and sublimation of its icy surface. Previous far-ultraviolet observations of the OI1356 Å and OI1304 Å oxygen emissions were used to derive sputtered molecular oxygen, O<sub>2,</sub> as an atmospheric constituent. We present a new analysis of high-sensitivity spectra and spectral images of Ganymede’s oxygen emissions acquired by the COS and STIS instruments on the Hubble Space Telescope. The COS eclipse observations constrain atomic oxygen, O, to be at least two orders of magnitude less abundant than O<sub>2</sub>. We then show that dissociative excitation of water vapor, H<sub>2</sub>O, is found to increase the OI1304 Å emissions relative to the OI1356 Å emissions around the sub-solar point, where H<sub>2</sub>O is more abundant than O<sub>2</sub>. Away from the sub-solar region, the emissions are more than two times brighter at OI1356 Å than at OI1304 Å, and O<sub>2</sub> prevails as found in previous analyses. A ~6-fold higher H<sub>2</sub>O/O<sub>2</sub> mixing ratio on the warmer trailing hemisphere compared to the colder leading hemisphere, a spatial concentration at the sub-solar region, and the ratio-estimated H<sub>2</sub>O densities identify icy surface sublimation as a local dayside atmospheric source.<br />Our analysis provides the first evidence for a sublimated atmosphere on an icy moon in the outer solar system.</p>


1999 ◽  
Vol 117 (1) ◽  
pp. 206-224 ◽  
Author(s):  
Noah Brosch ◽  
Michael Shara ◽  
John MacKenty ◽  
David Zurek ◽  
Brian McLean

2007 ◽  
Vol 380 (2) ◽  
pp. 828-834 ◽  
Author(s):  
Sebastian Jester ◽  
Klaus Meisenheimer ◽  
André R. Martel ◽  
Eric S. Perlman ◽  
William B. Sparks

2015 ◽  
Vol 33 (10) ◽  
pp. 1211-1219 ◽  
Author(s):  
B. Bonfond ◽  
J. Gustin ◽  
J.-C. Gérard ◽  
D. Grodent ◽  
A. Radioti ◽  
...  

Abstract. The aurorae at Jupiter are made up of many different features associated with a variety of generation mechanisms. The main auroral emission, also known as the main oval, is the most prominent of them as it accounts for approximately half of the total power emitted by the aurorae in the ultraviolet range. The energy of the precipitating electrons is a crucial parameter to characterize the processes at play which give rise to these auroral emissions, and the altitude of the emissions directly depends on this energy. Here we make use of far-UV (FUV) images acquired with the Advanced Camera for Surveys on board the Hubble Space Telescope and spectra acquired with the Space Telescope Imaging Spectrograph to measure the vertical profile of the main emissions. The altitude of the brightness peak as seen above the limb is ~ 400 km, which is significantly higher than the 250 km measured in the post-dusk sector by Galileo in the visible domain. However, a detailed analysis of the effect of hydrocarbon absorption, including both simulations and FUV spectral observations, indicates that FUV apparent vertical profiles should be considered with caution, as these observations are not incompatible with an emission peak located at 250 km. The analysis also calls for spectral observations to be carried out with an optimized geometry in order to remove observational ambiguities.


1995 ◽  
Vol 10 ◽  
pp. 626-627
Author(s):  
J.T. Clarke ◽  
R. Prangé ◽  
G.E. Ballester ◽  
J. Trauger ◽  
D. Rego ◽  
...  

2021 ◽  
Vol 923 (1) ◽  
pp. 102
Author(s):  
Theodore R. Gull ◽  
Felipe Navarete ◽  
Michael F. Corcoran ◽  
Augusto Damineli ◽  
David Espinoza ◽  
...  

Abstract Since 2002, the far-ultraviolet (FUV) flux (1150–1680 Å) of Eta Carinae, monitored by the Hubble Space Telescope/Space Telescope Imaging Spectrograph, has increased by an order of magnitude. This increase is attributed to partial dissipation of a line-of-sight (LOS) occulter that blocks the central core of the system. Across the 2020 February periastron passage, changes in the FUV emission show a stronger wavelength dependence than occurred across the 2003 July periastron passage. Across both periastron passages, most of the FUV spectrum dropped in flux then recovered a few months later. The 2020 periastron passage included enhancements of FUV flux in narrow spectral intervals near periastron followed by a transient absorption and recovery to pre-periastron flux levels. The drop in flux is due to increased absorption by singly ionized species as the secondary star plunges deep into the wind of the primary star, which blocks the companion’s ionizing radiation. The enhanced FUV emission is caused by the companion’s wind-blown cavity briefly opening a window to deeper layers of the primary star. This is the first time transient brightening has been seen in the FUV comparable to transients previously seen at longer wavelengths. Changes in resonance line-velocity profiles hint that the dissipating occulter is associated with material in LOS moving at −100 to −300 km s−1, similar in velocity of structures previously associated with the 1890s lesser eruption.


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