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

doi:10.1023/A:1021516418653

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

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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 language	English (US)
Pages (from-to)	89-97
Number of pages	9
Journal	Earth, Moon and Planets
Volume	90
Issue number	1-4
DOIs	https://doi.org/10.1023/A:1021516418653
State	Published - Mar 2002

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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10.1023/A:1021516418653

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

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-P{\'e}rot 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-P{\'e}rot 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.",

keywords = "C/1995 O1 (hale-bopp), Comets, Fabry-p{\'e}rot spectrometers, Hydrogen balmer-α coma, Line widths, Photolytic heating",

author = "Morgenthaler, {Jeffrey P.} and Harris, {Walter M.} and Frank Scherb and Doane, {Nathaniel E.} and Oliversen, {Ronald J.}",

note = "Funding Information: We would like to thank F. Roesler, E. Mierkiewicz, and M. Combi for valuable discussions. This work has been supported under NSF grant AST-9615625, NASA grant NAG 5-7952, and NASA contract NASW-97020.",

year = "2002",

month = mar,

doi = "10.1023/A:1021516418653",

language = "English (US)",

volume = "90",

pages = "89--97",

journal = "Earth, Moon and Planets",

issn = "0167-9295",

publisher = "Springer Netherlands",

number = "1-4",

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TY - JOUR

T1 - Velocity-resolved observations of Hα emission from comet C/1995 O1 (Hale-Bopp)

AU - Morgenthaler, Jeffrey P.

AU - Harris, Walter M.

AU - Scherb, Frank

AU - Doane, Nathaniel E.

AU - Oliversen, Ronald J.

N1 - Funding Information: We would like to thank F. Roesler, E. Mierkiewicz, and M. Combi for valuable discussions. This work has been supported under NSF grant AST-9615625, NASA grant NAG 5-7952, and NASA contract NASW-97020.

PY - 2002/3

Y1 - 2002/3

N2 - 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.

AB - 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.

KW - C/1995 O1 (hale-bopp)

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KW - Fabry-pérot spectrometers

KW - Hydrogen balmer-α coma

KW - Line widths

KW - Photolytic heating

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

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