J/ApJS/169/458 Highly excited H2 in Comets (Liu+, 2007)
Extreme Non-LTE H2in comets C/2000 WM1 (LINEAR) and C/2001 A2 (LINEAR).
Liu X., Shemansky D.E., Hallett J.T., Weaver H.A.
<Astrophys. J. Suppl. Ser., 169, 458-471 (2007)>
=2007ApJS..169..458L 2007ApJS..169..458L
ADC_Keywords: Comets ; Spectra, ultraviolet
Keywords: comets: general - comets: individual (C/2000 WM1, C/2001 A2) -
molecular processes - ultraviolet: solar system
Abstract:
Rotationally resolved molecular hydrogen transitions originating
from excitation of highly excited rovibrational levels of the
X1{SIGMA}+g state have been systematically identified for the
first time in the Far Ultraviolet Spectroscopic Explorer (FUSE)
observation of comets C/2000 WM1 (LINEAR) and C/2001 A2 (LINEAR).
Spectral assignments for the observed lines of H2 and other atomic
and molecular species are given. All observed H2 transitions belong
to the Lyman (B1{SIGMA}+u-X1σ+g) and Werner
(C1{PI}u-X1{SIGMA}+g) band systems. Resonant excitation of
H2 by Lyβ and other solar lines is very limited.
Description:
Detailed descriptions of the FUSE observations of comets C/2000 WM1
and C/2001 A2 have been given by Weaver et al. (2002ApJ...576L..95W 2002ApJ...576L..95W)
and Feldman et al. (2002ApJ...576L..91F 2002ApJ...576L..91F). The observation of comet
C/2001 A2 started on 2001 July 12 at 13:38 UT. Comet C/2000 WM1 was
observed between 2001 December 7 and 10.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 166 167 Observed Transitions and Spectral Assignments
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See also:
B/fuse : The FUSE Observation Log (FUSE, 1999-2007)
B/comets : Database of the orbital elements of comets (Rocher, 2007)
J/AJ/112/1197 : Catalog of cometary emission lines (Brown+ 1996)
J/PAZh/30/946 : Unidentified cometary emission lines (Simonia, 2004)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 8 F8.3 0.1nm Wave Observed center wavelength (1)
10 A1 --- n_Wave [de] Note on individual lines (2)
12- 16 F5.3 0.1nm FWHM Full-Width at Half-Maximum (1)
18- 20 A3 --- Comet [A2 WM1] Comet identification (4)
22- 87 A66 --- P-ID Primary line assignment (3)
89-166 A78 --- S-ID Secondary line assignment (3)
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Note (1): For the best-fit gaussian to the indicated spectral feature.
In units of Angstroms.
Note (2): Note as follows:
d = A small contribution from the 1(1,1)Q C (1028.989) emission is
possible, arising from pumping of the 1(1,5)Q C line (1206.639) by
Solar Si III lines whose rest and Doppler shifted (for comet A2)
wavelengths are 1206.510 and 1206.602Å, respectively. This
assignment is not listed in the Table because corresponding and
stronger lines for the (1,0), (1,3) and (1,4) bands are not identified.
e = The 3(1,1)Q C-X (1031.865) could be resonantly pumped by
O VI 2S1/2 - 2p 2P3/2 (1031.912) solar line. Even though the
strongest emission, 3(1,4)Q C-X (1163.805) can be identified in WM1,
the absence of the corresponding features for the (1,0) and (1,3) bands
at 989.729 and 1119.079Å, respectively, raised some questions.
Please refer to section 5 for discussion.
Note (3): The spectral carrier is H2 unless specified otherwise.
Transitions for H2 are labeled as Ji(vj,vi)ΔJβ,
where i and j refer to the lower and upper states, β is
electronic designation of excited state, and ΔJ=-1, 0 and +1
correspond to P, Q, and R transitions, respectively. Numbers in
parentheses are the model wavelength in Å. Transition followed by
single question mark (?) means that the assignment is possible but not
definitive. Lines with double question mark (??) indicates that no
reasonable assignment of H2 or other species is known to the authors
at the present time.
Note (4): A2 = Comet C/2001 A2 (LINEAR), and WM1 = Comet C/2000 WM1 (LINEAR)
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 29-Apr-2009