Far-Ultraviolet Studies. I. Predicted Far-Ultraviolet Interstellar Radiation Field

1977 ◽  
Vol 33 ◽  
pp. 451 ◽  
Author(s):  
Richard C. Henry
Keyword(s):  
Radiation Field ◽  
Far Ultraviolet

Far-ultraviolet studies. II - Galactic-latitude dependence of the 1530 A interstellar radiation field

1977 ◽  
Vol 212 ◽  
pp. 707 ◽  
Author(s):  
R. C. Henry ◽  
J. R. Swandic ◽  
S. D. Shulman ◽  
G. Fritz
Keyword(s):  
Radiation Field ◽  
Galactic Latitude ◽  
Latitude Dependence ◽  
Far Ultraviolet

Mass Loss from Stars

1977 ◽  
Vol 3 (2) ◽  
pp. 96-96
Author(s):  
Donald C. Morton
Keyword(s):  
Mass Loss ◽  
Radiation Field ◽  
Excited States ◽  
Short Wavelength ◽  
Hot Stars ◽  
Short Wavelength Side ◽  
Far Ultraviolet ◽  
Wavelength Side ◽  
Space Observations

The visual spectra of some hot stars, including P Cygni, have emission with associated absorption troughs ˜ 102 km s-1 on the short-wavelength side (Beals 1929, 1951). These P Cygni profiles are easily understood in terms of mass flowing away from the star. Later, rocket observations of the far-ultraviolet resonance lines (Morton 1967) showed that the phenomenon is rather common among hot stars and the velocity shifts could be from 1000 to 3000 km s-1, demonstrating that the mass must be escaping from the star. Resonance lines provide the strongest absorption in the shell where neither the density nor the radiation field is high enough to leave many ions in excited states. Since the ion stages likely to be present around a hot star have their resonance lines shortward of the atmospheric cutoff, space observations are essential in this investigation. Figure 1 shows the P Cygni profile of O VI in ς Pup obtained with Copernicus satellite spectrometer.

scholarly journals The Ionisation Equilibrium for Heavy Elements

1968 ◽  
Vol 34 ◽  
pp. 205-208
Author(s):  
D.R. Flower
Keyword(s):  
Radiation Field ◽  
Optical Depth ◽  
Cross Sections ◽  
Ground State ◽  
Spectral Region ◽  
Heavy Elements ◽  
First Approximation ◽  
Initial Work ◽  
Far Ultraviolet ◽  
Better Than

Calculations are being made of the distribution of the ions of heavy elements in planetary nebulae. Initial work has been concentrated on the central or He2+ zone of planetaries. The optical depths of ions of C, N, O, and Ne have been computed using ground state ionisation cross-sections and using approximations which should be substantially better than hydrogenic. A comparison has been made between the combined optical depth of the heavy elements and the optical depth of He+ in the far ultraviolet. The optical depths of the heavy elements in this spectral region may become significant, but a reasonable first approximation to the radiation field may be obtained by neglecting the absorption of all ions except He+. The distribution of the ions of the heavy elements has been calculated on this assumption.

scholarly journals Lyα DOMINANCE OF THE CLASSICAL T TAURI FAR-ULTRAVIOLET RADIATION FIELD

2012 ◽  
Vol 756 (1) ◽  
pp. L23 ◽  
Author(s):  
Eric Schindhelm ◽  
Kevin France ◽  
Gregory J. Herczeg ◽  
Edwin Bergin ◽  
Hao Yang ◽  
...  
Keyword(s):  
Ultraviolet Radiation ◽  
Radiation Field ◽  
T Tauri ◽  
Far Ultraviolet

scholarly journals An Analysis of 17 Years ofVoyagerObservations of the Diffuse Far‐Ultraviolet Radiation Field

1999 ◽  
Vol 522 (2) ◽  
pp. 904-914 ◽  
Author(s):  
Jayant Murthy ◽  
Doyle Hall ◽  
Matthew Earl ◽  
R. C. Henry ◽  
J. B. Holberg
Keyword(s):  
Ultraviolet Radiation ◽  
Radiation Field ◽  
Far Ultraviolet

scholarly journals The Interstellar Radiation Field and Its Interaction with the Interstellar Matter

1990 ◽  
Vol 139 ◽  
pp. 63-73 ◽  
Author(s):  
P. G. Mezger
Keyword(s):  
Radiation Field ◽  
Wavelength Range ◽  
Radiation Intensity ◽  
Spectral Distribution ◽  
Near Infrared ◽  
Blackbody Radiation ◽  
Interstellar Matter ◽  
Far Ultraviolet

Most stars emit most of their radiation in the wavelength range between the far ultraviolet (FUV) and near-infrared (IR). Eddington (1926) first estimated for the solar vicinity a mean radiation intensity of the interstellar radiation field (ISRF) equivalent to that of blackbody radiation of ~3 K but with a spectral distribution that can be approximated by ~10,000 K blackbody radiation diluted by a factor ≈ 10−14.

scholarly journals Photoevaporation of the Jovian circumplanetary disk

2020 ◽  
Vol 638 ◽  
pp. A135 ◽  
Author(s):  
N. Oberg ◽  
I. Kamp ◽  
S. Cazaux ◽  
Ch. Rab
Keyword(s):  
Radiation Field ◽  
Critical Mass ◽  
Incident Radiation ◽  
Outer Radius ◽  
Galilean Satellites ◽  
Stellar Cluster ◽  
Annular Gap ◽  
Hydrodynamical Simulations ◽  
Galilean System ◽  
Far Ultraviolet

Context. The Galilean satellites are thought to have formed from a circumplanetary disk (CPD) surrounding Jupiter. When it reached a critical mass, Jupiter opened an annular gap in the solar protoplanetary disk that might have exposed the CPD to radiation from the young Sun or from the stellar cluster in which the Solar System formed. Aims. We investigate the radiation field to which the Jovian CPD was exposed during the process of satellite formation. The resulting photoevaporation of the CPD is studied in this context to constrain possible formation scenarios for the Galilean satellites and explain architectural features of the Galilean system. Methods. We constructed a model for the stellar birth cluster to determine the intracluster far-ultraviolet (FUV) radiation field. We employed analytical annular gap profiles informed by hydrodynamical simulations to investigate a range of plausible geometries for the Jovian gap. We used the radiation thermochemical code PRODIMO to evaluate the incident radiation field in the Jovian gap and the photoevaporation of an embedded 2D axisymmetric CPD. Results. We derive the time-dependent intracluster FUV radiation field for the solar birth cluster over 10 Myr. We find that intracluster photoevaporation can cause significant truncation of the Jovian CPD. We determine steady-state truncation radii for possible CPDs, finding that the outer radius is proportional to the accretion rate Ṁ0.4. For CPD accretion rates Ṁ < 10−12M⊙ yr−1, photoevaporative truncation explains the lack of additional satellites outside the orbit of Callisto. For CPDs of mass MCPD < 10−6.2M⊙, photoevaporation can disperse the disk before Callisto is able to migrate into the Laplace resonance. This explains why Callisto is the only massive satellite that is excluded from the resonance.

VOYAGER OBSERVATIONS OF THE DIFFUSE FAR-ULTRAVIOLET RADIATION FIELD

2012 ◽  
Vol 199 (1) ◽  
pp. 11 ◽  
Author(s):  
Jayant Murthy ◽  
Richard Conn Henry ◽  
Jay B. Holberg
Keyword(s):  
Ultraviolet Radiation ◽  
Radiation Field ◽  
Far Ultraviolet
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