[en] The helium resonance line at 584 Å has been observed with the UltraViolet Imaging Spectrograph (UVIS) Extreme Ultraviolet channel during the flyby of Venus by Cassini at a period of high solar activity. The brightness was measured along the disk from the morning terminator up to the bright limb near local noon. The mean disk intensity was ˜320 R, reaching ˜700 R at the bright limb. These values are slightly higher than those determined from previous observations. The sensitivity of the 584 Å intensity to the helium abundance is analyzed using recent cross-sections and solar irradiance measurements at 584 Å. The intensity distribution along the UVIS footprint on the disk is best reproduced using the EUVAC solar flux model and the helium density distribution from the VTS3 empirical model. It corresponds to a helium density of 8×10[SUP]6[/SUP] cm[SUP]-3[/SUP] at the level of where the CO[SUB]2[/SUB] is 2×10[SUP]10[/SUP] cm[SUP]-3[/SUP].
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Gérard, Jean-Claude ; Laboratoire de Physique Atmosphérique et Planétaire, Université de Liège, 17, allée du 6 août, B5c, B-4000 Liège, Belgium
Gustin, Jacques ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)
Hubert, Benoît ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)
Gladstone, G. R.; Southwest Research Institute, P.O. Drawer 28510, 6220 Culebra Road, San Antonio, TX 78238-5166, USA
Esposito, L. W.; Laboratory for Atmospheric and Space Physics, University of Colorado, Campus Box 392, Boulder, CO 80309-0392, USA
Language :
English
Title :
Measurements of the helium 584 Å airglow during the Cassini flyby of Venus
Publication date :
01 October 2011
Journal title :
Planetary and Space Science
ISSN :
0032-0633
Publisher :
Pergamon Press - An Imprint of Elsevier Science, Oxford, United Kingdom
S. Barabash The loss of ions from Venus through the plasma wake Nature 450 2007 650 653 10.1038/nature06434 (Pubitemid 350207703)
J.L. Bertaux, J.E. Blamont, V.M. Lepine, V.G. Kurt, N.N. Romanova, and A.S. Smirnov Venera 11 and Venera 12 observations of E.U.V. emissions from the upper atmosphere of Venus Planet. Space Sci. 29 1981 149 166
Chassefière, E.; Bertaux, J.L.; Kurt, V.G.; Smirnov, A.S.; 1986. Venus e.u.v. measurements of helium at 58.4 nm from Venera 11 and Venera 12 and implications for the outgassing history. Planet. Space Sci. 34, 585602, doi:10.1016/0032-0633(86)90037-1.
L.W. Esposito The Cassini Ultraviolet Imaging Spectrograph investigation Space Sci. Rev. 115 2004 299 361 10.1007/s11214-004-1455-8
Gérard, J.-C.; Hubert, B.; Gustin, J.; Shematovich, V.I.; Bisikalo, D.; Gladstone, G.R.; Esposito, L.W.; 2011. EUV spectroscopy of the Venus dayglow with UVIS on Cassini during the Cassini flyby, Icarus 211, 7080, doi:10.1016/j.icarus.2010.09.020.
G.R. Gladstone Radiative transfer of resonance lines with internal sources J. Quant. Spectr. Radiat. Transfer 33 1985 453 458
A.E. Hedin, H.B. Niemann, W.T. Kasprzak, and A. Seiff Global empirical model of the Venus thermosphere J. Geophys. Res. 88 1983 73 83
B. Hubert, J.-C. Gérard, J. Gustin, V.I. Shematovich, D.V. Bisikalo, A.I. Stewart, G.R. Gladstone, and L. Esposito UVIS observations of the FUV OI and CO Venus dayglow Icarus 207 2010 549 557 10.1016/j.icarus.2009.12. 029
D.L. Huestis, and J. Berkowitz Critical evaluation of the photoabsorption cross section of CO2 from 0.125 to 201.6 nm at room temperature Bull. Am. Astron. Soc. 42 2010 972
V.A. Krasnopolsky, and G.R. Gladstone Helium on Mars and Venus: EUVE observations and modeling Icarus 176 2005 395 407 10.1016/j.icarus.2005.02.005 (Pubitemid 40935820)
S. Kumar, and A.L. Broadfoot He 584 Å airglow emission from Venus: Mariner 10 observations Geophys. Res. Lett. 2 1975 357 360. doi: 10.1029/GL002i008p00357
J.O. Maloy, R.W. Carlson, U.G. Hartmann, and D.L. Judge Measurement of the profile and intensity of the solar He I λ584-Å resonance line J. Geophys. Res. 83 1978 5685 5690 10.1029/JA083iA12p05685
H.B. Niemann, W.T. Kasprzak, A.E. Hedin, D.M. Hunten, and N.W. Spencer Mass spectrometric measurements of the neutral gas composition of the thermosphere and exosphere of Venus J. Geophys. Res. 85 1980 7817 7827 10.1029/JA085iA13p07817
H.S. Ogawa, E. Phillips, and D.L. Judge Line width of the solar EUV He I, resonance emissions at 584 and 537 Å J. Geophys. Res. 89 1984 7537 7540 (Pubitemid 14650151)
J.B. Pollack, and D.C. Black Noble gases in planetary atmospheres: implications for the origin and evolution of atmospheres Icarus 51 1982 1982 169 198 10.1016/0019-1035(82)90079-3
M.J Prather, and M.B McElroy Helium on Venus: implications for uranium and thorium Science 220 1983 410 411 (Pubitemid 17253267)
P.G. Richards, J.A. Fennelly, and D.G. Torr EUVAC: a solar EUV flux model for aeronomic calculations J. Geophys. Res. 99 1994 8981 8992. doi: 10.1029/94JA00518
D.A. Shaw, D.M.P. Holland, M.A. Hayes, M.A. MacDonald, A. Hopkirk, and S.M. McSweene A study of the absolute photoabsorption, photoionisation and photodissociation cross sections and the photoionisation quantum efficiency of carbon dioxide from the ionisation threshold to 345 Å Chem. Phys. 198 1995 381 396
A.J. Steffl, A.I.F. Stewart, and F. Bagenal. Cassini UVIS observations of the Io plasma torus. I. Initial results Icarus 172 2004 78 90 10.1016/j.icarus.2003.12.027 (Pubitemid 39442782)
von Zahn, U.; Fricke, K.H.; Hunten, D.M.; Krankowski, D.; Mauersberger, K.; Nier, A.O. 1980. The upper atmosphere of Venus during morning conditions, J. Geophys. Res.; 85, 7829-7840
U. von Zahn, S. Kumar, H. Niemann, and R. Prinn Composition of the Venus atmosphere D.M Hunten, L Colin, T. Donahue, T.M. Moroz, Venus 1983 University of Arizona Press Tucson, AZ 299 430
W.L. Wiese, and J.R. Fuhr Accurate atomic transition probabilities for hydrogen, helium, and lithium J. Phys. Chem. Ref. Data 38 2009 565 719 10.1063/1.3077727
K. Wilhelm, P. Lemaire, W. Curdt, U. Schühle, E. Marsch, A.I. Poland, S.D. Jordan, R.J. Thomas, D.M. Hassler, and M.C.E. Huber First results of the SUMER telescope and spectrometer on SOHO - I. Spectra and Spectroradiometry Sol. Phys. 170 1997 75 104 10.1023/A:1004923511980 (Pubitemid 127041126)
T. Woods, and G. Rottman Ultraviolet variability over time periods of aeronomic interest, in atmospheres in the solar system: comparative aeronomy M. Mendillo, A. Nagy, J.H. Waite, Geophysical Monograph 130 2002 American Geophysical Union Washington, DC 221
