Comet Hale-Bopp Spectra


Spectrum of the coma of comet Hale-Bopp within 20 arcsec of the nucleus taken April 13, 1997 by Rod Heyd, Susan Wyckoff and Peter Wehinger with the Steward Observatory 2.3-m telescope and CCD cassegrain spectrograph. The spectrograph slit was oriented at a position angle of 49 degrees (in the predicted anti-solar direction), and the length of the slit at the comet was about 100,000 km. The strongest molecular emission features in the coma of comet Hale-Bopp are identified. Cyanogen (CN) and molecular carbon (C2) dominate the coma in the visible wavelength region of the spectrum. The sodium (Na I) emission line near 5800 Angstroms may be associated with the sodium tail reported by G. Cremonese on behalf of the European Hale-Bopp team on April 18, 1997. The darker vertical features throughout the spectrum are absorption lines in the solar continuum reflected from the comet dust in the coma.
Spectrum of the plasma tail of comet Hale-Bopp taken April 13, 1997 (UT) by Rod Heyd, Susan Wyckoff and Peter Wehinger with the Steward Observatory 2.3-m telescope and CCD cassegrain spectrograph. The spectrograph slit (corresponding to a length of 100,000 km at the comet) was aligned along the anti-solar direction, and offset 2 degrees from the nucleus at a position angle of 49 degrees (predicted anti-solar direction). The strongest lines in the spectrum are labeled. The ionized carbon monoxide emission features (strongest in the blue) dominate the visible region of the spectrum, and account for the blue plasma tail seen in CCD direct images and photographs. Also present in the plasma tail spectrum are weak features due to ionized water (H2O+) and, possibly, ionized carbon dioxide (CO2+). The Na I emission is probably due to the sodium comet tail which was reported by G. Cremonese on behalf of the European Hale-Bopp team on April 18, 1997 (IAU Circ. No. 6631). The [OI] lines arise in the comet from the break-up of the water molecules by sunlight.

Created by Rod Heyd, Last modified 23 April 1997