scholarly journals Eta Carinae: A Tale of Two Periastron Passages

2021 ◽  
Vol 923 (1) ◽  
pp. 102
Author(s):  
Theodore R. Gull ◽  
Felipe Navarete ◽  
Michael F. Corcoran ◽  
Augusto Damineli ◽  
David Espinoza ◽  
...  
Keyword(s):  
Transient Absorption ◽  
Hubble Space Telescope ◽  
Wavelength Dependence ◽  
Primary Star ◽  
Space Telescope ◽  
Eta Carinae ◽  
Secondary Star ◽  
Order Of Magnitude ◽  
Far Ultraviolet ◽  
First Time

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.

scholarly journals A Hubble Space Telescope STIS Observation of VW Hydri at the Exact Far-Ultraviolet Onset of an Outburst

2004 ◽  
Vol 614 (1) ◽  
pp. L61-L64 ◽  
Author(s):  
Edward M. Sion ◽  
F. H. Cheng ◽  
Boris T. Gänsicke ◽  
Paula Szkody
Keyword(s):  
Hubble Space Telescope ◽  
Space Telescope ◽  
Far Ultraviolet

Astrometric Analysis of the Homunculus of eta Carinae With the Hubble Space Telescope

1996 ◽  
Vol 112 ◽  
pp. 1115 ◽  
Author(s):  
Douglas G. Currie ◽  
Daniel M. Dowling ◽  
Edward J. Shaya ◽  
Jeff Hester ◽  
Paul Scowen ◽  
...  
Keyword(s):  
Hubble Space Telescope ◽  
Space Telescope ◽  
Eta Carinae

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 ◽  
...  
Keyword(s):  
Hubble Space Telescope ◽  
Space Telescope ◽  
Far Ultraviolet

scholarly journals A far-UV survey of three hot, metal-polluted white dwarf stars: WD0455−282, WD0621−376, and WD2211−495

2019 ◽  
Vol 487 (3) ◽  
pp. 3470-3487 ◽  
Author(s):  
Simon P Preval ◽  
Martin A Barstow ◽  
Matthew Bainbridge ◽  
Nicole Reindl ◽  
Thomas Ayres ◽  
...  
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Hubble Space Telescope ◽  
Line Of Sight ◽  
Hot Metal ◽  
Dwarf Stars ◽  
High Resolution Data ◽  
White Dwarf Stars ◽  
Order Of Magnitude ◽  
Far Ultraviolet

ABSTRACT Using newly obtained high-resolution data (R ∼ 1 × 105) from the Hubble Space Telescope, and archival UV data from the Far Ultraviolet Spectroscopic Explorer, we have conducted a detailed UV survey of the three hot, metal-polluted white dwarfs WD0455−282, WD0621−376, and WD2211−495. Using bespoke model atmospheres, we measured Teff, log g, and photospheric abundances for these stars. In conjunction with data from Gaia, we measured masses, radii, and gravitational redshift velocities for our sample of objects. We compared the measured photospheric abundances with those predicted by radiative levitation theory, and found that the observed Si abundances in all three white dwarfs, and the observed Fe abundances in WD0621−376 and WD2211−495, were larger than those predicted by an order of magnitude. These findings imply not only an external origin for the metals, but also ongoing accretion, as the metals not supported by radiative levitation would sink on extremely short time-scales. We measured the radial velocities of several absorption features along the line of sight to the three objects in our sample, allowing us to determine the velocities of the photospheric and interstellar components along the line of sight for each star. Interestingly, we made detections of circumstellar absorption along the line of sight to WD0455−282 with three velocity components. To our knowledge, this is the first such detection of multicomponent circumstellar absorption along the line of sight to a white dwarf.

scholarly journals Properties of reionization-era galaxies from JWST luminosity functions and 21-cm interferometry

2019 ◽  
Vol 491 (3) ◽  
pp. 3891-3899 ◽  
Author(s):  
Jaehong Park ◽  
Nicolas Gillet ◽  
Andrei Mesinger ◽  
Bradley Greig
Keyword(s):  
Star Formation Rate ◽  
Hubble Space Telescope ◽  
Formation Rate ◽  
Power Spectra ◽  
Mass Relation ◽  
Space Telescope ◽  
James Webb Space Telescope ◽  
Luminosity Functions ◽  
Order Of Magnitude ◽  
Magnitude Improvement

ABSTRACT Upcoming observations will probe the first billion years of our Universe in unprecedented detail. Foremost among these are 21-cm interferometry with the Hydrogen Epoch of Reionization Arrays (HERA) and the Square Kilometre Array (SKA), and high-z galaxy observations with the James Webb Space Telescope (JWST). Here, we quantify how observations from these instruments can be used to constrain the astrophysics of high-z galaxies. We generate several mock JWST luminosity functions (LFs) and SKA1 21-cm power spectra, which are consistent with current observations, but assume different properties for the unseen, ultrafaint galaxies driving the epoch of reionization (EoR). Using only JWST data, we predict up to a factor of 2–3 improvement (compared with Hubble Space Telescope, HST) in the fractional uncertainty of the star formation rate to halo mass relation and the turnover magnitude. Most parameters regulating the ultraviolet (UV) galaxy properties can be constrained at the level of ∼10 per cent or better, if either (i) we are able to better characterize systematic lensing uncertainties than currently possible; or (ii) the intrinsic LFs peak at magnitudes brighter than MUV ≲ −13. Otherwise, improvement over HST-based inference is modest. When combining with upcoming 21-cm observations, we are able to significantly mitigate degeneracies, and constrain all of our astrophysical parameters, even for our most pessimistic assumptions about upcoming JWST LFs. The 21-cm observations also result in an order of magnitude improvement in constraints on the EoR history.

Far-ultraviolet spectroscopy of the quasar UM 675 with the faint object spectrograph on the Hubble Space Telescope

1991 ◽  
Vol 377 ◽  
pp. L1 ◽  
Author(s):  
E. A. Beaver ◽  
E. M. Burbidge ◽  
Ross D. Cohen ◽  
Vesa T. Junkkarinen ◽  
Ronald W. Lyons ◽  
...  
Keyword(s):  
Hubble Space Telescope ◽  
Ultraviolet Spectroscopy ◽  
Space Telescope ◽  
Faint Object ◽  
Far Ultraviolet ◽  
Faint Object Spectrograph

Hubble Space Telescope detects sub-solar water atmosphere on Ganymede

2021 ◽  
Author(s):  
Lorenz Roth ◽  
Nickolay Ivchenko ◽  
Randy Gladstone ◽  
Joachim Saur ◽  
Denis Grodent ◽  
...  
Keyword(s):  
Atomic Oxygen ◽  
Hubble Space Telescope ◽  
High Sensitivity ◽  
Dissociative Excitation ◽  
Mixing Ratio ◽  
Space Telescope ◽  
Eclipse Observations ◽  
Far Ultraviolet ◽  
Ultraviolet Observations ◽  
Atmospheric Constituent

<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>

Spectroscopy of the C2 molecule: Valence and Rydberg states in the 7–10 eV region. An ab initio study

2001 ◽  
Vol 79 (2-3) ◽  
pp. 653-671 ◽  
Author(s):  
P J Bruna ◽  
F Grein
Keyword(s):  
Absorption Band ◽  
Ab Initio ◽  
Hubble Space Telescope ◽  
Mixed Valence ◽  
Rydberg States ◽  
Ab Initio Study ◽  
Space Telescope ◽  
First Time ◽  
Potential Curves ◽  
Singlet Transition

The potential curves of selected valence and Rydberg states of C2 lying in the 7–10 eV region are reported for the first time. The states studied, using MRCI wave funtions, include (2–5)3,1Πu, (1–3)3Σ+g, (2–5)3Σ–g, (1–3)3Δg, and relevant quintet states. The f 3Σ–g, g3Δg, and F1Πu states observed in absorption from 8.88 to 9.25 eV by Herzberg et al. have originally been assumed to be πu ® 3s Rydberg states, with respect to a 3Πu(13Πu) for the triplets and to X1Σg+ for the singlet. Our calculations partially support such assignments: f 3 Σg– corresponding to 33Σg– has mixed valence σuσgπu 3πg and Rydberg σu 2σgπu 23s character, g 3Δg corresponding to 23 Δg has a valence σuσgπu 3πg structure, while F 1 Πu(21Πu) is confirmed to be a σu 2πu 33s state. The calculated f00-values for these bands are 0.027 for f¬ a, 0.051 for g ¬ a, and 0.098 for F ¬ X. The singlet–singlet transition F ¬ X constitutes the strongest absorption band reported so far for C2. Our theoretical value agrees with f00(F¬X) = 0.10 ± 0.01 derived indirectly from interstellar data collected by the Hubble Space Telescope. The 13Σg+ (σuσgπu 3πg) state at Te = 7.57 eV lies much higher than expected by experimentalists. PACS Nos.: 31.20T, 31.50, 33.20N, 33.70. PACS Nos.: 31.20T, 31.50, 33.20N, 33.70.

Far-Ultraviolet Imaging of the Field Star Population in the Large Magellanic Cloud with the [ITAL]Hubble Space Telescope[/ITAL]

1999 ◽  
Vol 117 (1) ◽  
pp. 206-224 ◽  
Author(s):  
Noah Brosch ◽  
Michael Shara ◽  
John MacKenty ◽  
David Zurek ◽  
Brian McLean
Keyword(s):  
Hubble Space Telescope ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Space Telescope ◽  
Field Star ◽  
Far Ultraviolet
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