DPS 35th Meeting, 1-6 September 2003
Session 33. Planetary Bookends II
Poster, Highlighted on, Friday, September 5, 2003, 3:30-6:00pm, Sierra Ballroom I-II

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[33.05] Long-term Observations of Sodium on Mercury

A.E. Potter (National Solar Observatory), R.M. Killen (University of Maryland), T.H. Morgan (NASA Headquarters)

We are re-processing Mercury sodium observations that were obtained during the past decade. The main products are planetary sodium images chosen for the best seeing conditions, and planetary-average sodium column densities derived from the D1 emission intensity to minimize errors from optical thickness of the sodium. Some image sequences are constant and stable, while others display day-to-day changes that may be correlated with solar activity. Most of the images show peak sodium intensities in southern latitudes. A few images show both north and south peaks, and another few show a northern latitude peak only. The planetary-average sodium column densities are mostly in the range 1-2 x 1011 atoms per cm2 column, but occasionally are a factor of three higher or lower. The column densities are a maximum at both aphelion and perihelion, suggesting that solar radiation acceleration pressure reduces sodium density between aphelion and perihelion. This work is supported by the NASA Planetary Astronomy Program.

The author(s) of this abstract have provided an email address for comments about the abstract: apotter@noao.edu

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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.