J/ApJ/855/134 UV spectrum of molecular hydrogen in the Sun (Jaeggli+, 2018)
Formation of the UV spectrum of molecular hydrogen in the Sun.
Jaeggli S.A., Judge P.G., Daw A.N.
<Astrophys. J., 855, 134 (2018)>
=2018ApJ...855..134J 2018ApJ...855..134J
ADC_Keywords: Models, atmosphere; Sun; Spectra, ultraviolet; Molecular data
Keywords: line: formation; molecular processes; radiative transfer;
Sun: chromosphere; Sun: UV radiation
Abstract:
Ultraviolet (UV) lines of molecular hydrogen have been observed in
solar spectra for almost four decades, but the behavior of the
molecular spectrum and its implications for solar atmospheric
structure are not fully understood. Data from the High-Resolution
Telescope Spectrometer (HRTS) instrument revealed that H2 emission
forms in particular regions, selectively excited by a bright UV
transition region and chromospheric lines. We test the conditions
under which H2 emission can originate by studying non-LTE models,
sampling a broad range of temperature stratifications and radiation
conditions. Stratification plays the dominant role in determining the
population densities of H2, which forms in greatest abundance near the
continuum photosphere. However, opacity due to the photoionization of
Si and other neutrals determines the depth to which UV radiation can
penetrate to excite the H2. Thus the majority of H2 emission forms in
a narrow region, at about 650km in standard one-dimensional (1D)
models of the quiet Sun, near the τ=1 opacity surface for the
exciting UV radiation, generally coming from above. When irradiated
from above using observed intensities of bright UV emission lines,
detailed non-LTE calculations show that the spectrum of H2 seen in the
quiet-Sun Solar Ultraviolet Measurement of Emitted Radiation atlas
spectrum and HRTS light-bridge spectrum can be satisfactorily
reproduced in 1D stratified atmospheres, without including
three-dimensional or time-dependent thermal structures. A detailed
comparison to observations from 1205 to 1550Å is presented, and the
success of this 1D approach to modeling solar UV H2 emission is
illustrated by the identification of previously unidentified lines and
upper levels in HRTS spectra.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
fig5.dat 159 69539 *Synthetic H2 fluorescence spectra generated with
the FALC, COX, and F2 atmospheres
dataA.dat 61 27981 Parameters for lines of the H2 Lyman and Werner bands
dataB.dat 293 27981 H2 line-integrated intensities and primary excitation
wavelength for each of the model scenarios
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Note on fig5.dat: We have selected three diverse 1D semi-empirical atmospheric
models for the calculations: the average quiet-Sun model atmosphere "C" from
Fontenla+ (1993ApJ...406..319F 1993ApJ...406..319F) (henceforth FALC), the cool model atmosphere
COX from Avrett (1995itsa.conf..303A), and the F2 flare model atmosphere
from Machado+ (1980ApJ...242..336M 1980ApJ...242..336M).
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See also:
J/A+AS/141/297 : H2 total transition probability (Abgrall+, 2000)
J/A+A/375/591 : SUMER Spectral Atlas of Solar Disk Features (Curdt+, 2001)
J/A+A/588/A96 : Partition functions for molecules and atoms (Barklem+, 2016)
Byte-by-byte Description of file: fig5.dat
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Bytes Format Units Label Explanations
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1- 9 F9.4 0.1nm lambda [910/1800] Wavelength; Angstroms
11- 19 E9.3 cW/m2/nm/sr i01 [3.4/182300] Spectral intensity
from FALCx1cutoff (1)
21- 29 E9.3 cW/m2/nm/sr i02 [3.8/444600] Spectral intensity
from FALCx3cutoff (1)
31- 39 E9.3 cW/m2/nm/sr i03 [4.9/1.4e+06] Spectral intensity
from FALCx10cutoff (1)
41- 49 E9.3 cW/m2/nm/sr i04 [8.7/2.2e+06] Spectral intensity
from FALCx30cutoff (1)
51- 59 E9.3 cW/m2/nm/sr i05 [16/7.3e+06] Spectral intensity
from FALCx100cutoff (1)
61- 69 E9.3 cW/m2/nm/sr i06 [0.1/142200] Spectral intensity
from COXx1cutoff (1)
71- 79 E9.3 cW/m2/nm/sr i07 [0.2/417400] Spectral intensity
from COXx3cutoff (1)
81- 89 E9.3 cW/m2/nm/sr i08 [0.5/1.4e+06] Spectral intensity
from COXx10cutoff (1)
91- 99 E9.3 cW/m2/nm/sr i09 [1.2/2.2e+06] Spectral intensity
from COXx30cutoff (1)
101-109 E9.3 cW/m2/nm/sr i10 [2.2/7.3e+06] Spectral intensity
from COXx100cutoff (1)
111-119 E9.3 cW/m2/nm/sr i11 [2501/6.3e+07] Spectral intensity
from F2x1cutoff (1)
121-129 E9.3 cW/m2/nm/sr i12 [2501/6.4e+07] Spectral intensity
from F2x3cutoff (1)
131-139 E9.3 cW/m2/nm/sr i13 [2503/6.4e+07] Spectral intensity
from F2x10cutoff (1)
141-149 E9.3 cW/m2/nm/sr i14 [2508/6.5e+07] Spectral intensity
from F2x30cutoff (1)
151-159 E9.3 cW/m2/nm/sr i15 [2524/7e+07] Spectral intensity
from F2x100cutoff (1)
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Note (1): In units of erg/s/cm2/Angstrom/Sr.
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Byte-by-byte Description of file: dataA.dat
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Bytes Format Units Label Explanations
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1- 8 F8.3 0.1nm Wave [844.8/1844.6] Wavelength; Angstroms
10- 11 I2 --- Ji [0/26] Lower level angular momentum quantum number
13- 14 I2 --- vi [0/14] Lower level vibrational quantum number
16 A1 --- ci [X] Lower level configuration
18- 25 F8.2 cm-1 Ei [0/36105] Lower level energy
27- 28 I2 --- Jj [0/25] Upper level angular momentum quantum number
30- 31 I2 --- vj [0/37] Upper level vibrational quantum number
33- 34 A2 --- cj Upper level configuration
36- 44 F9.2 cm-1 Ej [90203/118376] Upper level energy
46- 54 E9.3 s-1 Aji [1e-06/6.2e+08] Einstein coefficient
for spontaneous emission
56- 61 F6.4 --- PB [0.004/1] Probability upper level decays to
a bound state
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Byte-by-byte Description of file: dataB.dat
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Bytes Format Units Label Explanations
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1- 8 F8.3 0.1nm Wave [844.8/1844.6] Emitting line wavelength; Angstroms
10- 18 E9.3 mW/m2/sr il01 [0/242.3] Line intensity from FALCx1cutoff (1)
20- 27 F8.3 0.1nm wp01 [1103.2/1520] Wavelength of primary pump
from FALCx1cutoff
29- 37 E9.3 mW/m2/sr il02 [0/242.6] Line intensity from FALCx3cutoff (1)
39- 46 F8.3 0.1nm wp02 [977/1520] Wavelength of primary pump
from FALCx3cutoff
48- 56 E9.3 mW/m2/sr il03 [0/243.6] Line intensity from FALCx10cutoff (1)
58- 65 F8.3 0.1nm wp03 [976.8/1520] Wavelength of primary pump
from FALCx10cutoff
67- 75 E9.3 mW/m2/sr il04 [0/248.2] Line intensity from FALCx30cutoff (1)
77- 84 F8.3 0.1nm wp04 [976.6/1520] Wavelength of primary pump
from FALCx30cutoff
86- 94 E9.3 mW/m2/sr il05 [0/266.2] Line intensity from FALCx100cutoff (1)
96-103 F8.3 0.1nm wp05 [919.8/1520] Wavelength of primary pump
from FALCx100cutoff
105-113 E9.3 mW/m2/sr il06 [0/274.6] Line intensity from COXx1cutoff (1)
115-122 F8.3 0.1nm wp06 [912/1518.2] Wavelength of primary pump
from COXx1cutoff
124-132 E9.3 mW/m2/sr il07 [0/274.2] Line intensity from COXx3cutoff (1)
134-141 F8.3 0.1nm wp07 [912/1518.2] Wavelength of primary pump
from COXx3cutoff
143-151 E9.3 mW/m2/sr il08 [0/274.3] Line intensity from COXx10cutoff (1)
153-160 F8.3 0.1nm wp08 [912/1520] Wavelength of primary pump
from COXx10cutoff
162-170 E9.3 mW/m2/sr il09 [0/276.7] Line intensity from COXx30cutoff (1)
172-179 F8.3 0.1nm wp09 [912/1520] Wavelength of primary pump
from COXx30cutoff
181-189 E9.3 mW/m2/sr il10 [0/449.6] Line intensity from COXx100cutoff (1)
191-198 F8.3 0.1nm wp10 [912/1515] Wavelength of primary pump
from COXx100cutoff
200-208 E9.3 mW/m2/sr il11 [0/4841] Line intensity from F2x1cutoff (1)
210-217 F8.3 0.1nm wp11 [1103.2/1520] Wavelength of primary pump
from F2x1cutoff
219-227 E9.3 mW/m2/sr il12 [0/4841] Line intensity from F2x3cutoff (1)
229-236 F8.3 0.1nm wp12 [1103.2/1520] Wavelength of primary pump
from F2x3cutoff
238-246 E9.3 mW/m2/sr il13 [0/4842] Line intensity from F2x10cutoff (1)
248-255 F8.3 0.1nm wp13 [1103.2/1520] Wavelength of primary pump
from F2x10cutoff
257-265 E9.3 mW/m2/sr il14 [0/4845] Line intensity from F2x30cutoff (1)
267-274 F8.3 0.1nm wp14 [1103.2/1520] Wavelength of primary pump
from F2x30cutoff
276-284 E9.3 mW/m2/sr il15 [0/4856] Line intensity from F2x100cutoff (1)
286-293 F8.3 0.1nm wp15 [1103.2/1520] Wavelength of primary pump
from F2x100cutoff
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Note (1): In units of erg/s/cm2/sr.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 21-Jan-2019