Venus tail ray observation near Earth

• Published in: Geophysical research letters 1997-05, Vol.24 (10), p.1163-1166
• Main Authors: Grünwaldt, H., Neugebauer, M., Hilchenbach, M., Bochsler, P., Hovestadt, D., Bürgi, A., Ipavich, F. M., Reiche, K.-U., Axford, W. I., Balsiger, H., Galvin, A. B., Geiss, J., Gliem, F., Gloeckler, G., Hsieh, K. C., Kallenbach, R., Klecker, B., Livi, S., Lee, M. A., Managadze, G. G., Marsch, E., Möbius, E., Scholer, M., Verigin, M. I., Wilken, B., Wurz, P.
• Format: Article
• Language: English
• Subjects: Density; Detectors; Earth; Fluxes; Geophysics; Neutral atoms; Solar wind; Venus
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/97GL01159

In June, 1996, Venus passed through a very close inferior conjunction with the Sun. At that time the CTOF detector of the CELIAS mass spectrometer experiment on the SOHO spacecraft near Earth's L1 Lagrangian point was measuring heavy ions in the solar wind ∼4.5 × 107 km downstream of Venus. Close to the time predicted by simple geometric arguments for passage of SOHO through the Venus wake, CTOF made three encounters with unusual fluxes of O+ and C+ ions. Their energy distributions resembled those of tail rays originating in the Venus ionosphere or ionopause region rather than of ions produced in the corona of neutral atoms that surrounds the planet. The C+ abundance was ≈ 10% of O+. The observed O+ speed was very close to the simultaneous solar wind speed and the O+ temperature was a cool 5600 K/amu. The flux densities for the three events were (2.4–4.4) × 10³ cm−2s−1.