HIGH-DISPERSION SPECTROSCOPY OF THE SODIUM (NA) EMISSION WITHIN THE INNER COMA OF C/1995 O1 (HALE–BOPP)


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Abstract

Very-high spectral resolution observations of the neutral Na emission have enabled measurements of the velocity dispersions of the Na atoms within ∼40,000 km of the optocenter of Hale–Bopp. Asymmetric Na D line profiles imply both an in situ or core Na source and a secondary Na source at locations within the inner coma. The core velocity distribution had a FWHM of 2 km s-1. The extended source FWHM increased with distance from the nucleus (up to ∼6 km s-1)), but appeared smaller in the more dusty regions (∼2.5–3.0 km s-1)) of the inner coma. The D2/D1line strength ratio was consistent with an optically thin inner coma. Within 5,000 km of the optocenter the continuum spatial intensity profiles decreased as ∼r-1while the Na D emission decreased at less than r-1.

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