Velocity-resolved observations of Hα emission from comet C/1995 O1 (Hale-Bopp)

Jeffrey P. Morgenthaler, Walter M. Harris, Frank Scherb, Nathaniel E. Doane, Ronald J. Oliversen

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

We present hydrogen Balmer-α spectra of comet C/1995 O1 (Hale-Bopp) recorded on 5 nights from 1997 February 1 to April 19 by a high-resolution (Δ v = 5 km s-1) Fabry-Pérot spectrometer for a 4′. 1 (∼2.7 × 105 km) FOV centered 5′ sunward of the nucleus. The Hα line profile is an important diagnostic of photolytic heating in cometary atmospheres. Extraction of the spectra from the Fabry-Pérot ring images was complicated by obscuration of the telescope FOV due to Hale-Bopp's low elevation, but the measured H-α line widths of 11-13 km s-1 (FWHM) are insensitive to the spectral extraction technique. The line widths are consistent with estimates derived from a successful model of Hale-Bopp's hydrogen Lyman-α coma assuming the inner coma is opaque to Hα. We discuss methods for improving the spectral extraction technique and deriving a precise instrument profile which will allow the detailed shape of the line profile to constrain coma models.

Original languageEnglish (US)
Pages (from-to)89-97
Number of pages9
JournalEarth, Moon and Planets
Volume90
Issue number1-4
DOIs
StatePublished - Mar 1 2002
Externally publishedYes

Keywords

  • C/1995 O1 (hale-bopp)
  • Comets
  • Fabry-pérot spectrometers
  • Hydrogen balmer-α coma
  • Line widths
  • Photolytic heating

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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