Rejection of the C-7 diffuse interstellar band hypothesis

B. J. McCall; J. Thorburn; L. M. Hobbs; T. Oka; D. G. York

doi:10.1086/323669

Rejection of the C^-₇ diffuse interstellar band hypothesis

B. J. McCall, J. Thorburn, L. M. Hobbs, T. Oka, D. G. York

Research output: Contribution to journal › Article › peer-review

Abstract

Using the new high-resolution (∼8 km s^-1) echelle spectrograph on the 3.5 m telescope at the Apache Point Observatory, we have begun a high-sensitivity survey of the diffuse interstellar bands (DIBs) in a large sample of reddened stars. Now that we are 2 years into this long-term survey, our sample includes over 20 reddened stars that show at least one of the DIBs that had been suggested to be caused by C^-₇, based on the gas-phase measurement of the C^-₇ spectrum by J. P. Maier's group. The high-quality astronomical data from this larger sample of stars, along with the spectroscopic constants from the new laboratory work recently reported by Maier's group, have enabled us to examine more carefully the agreement between C^-₇ and the DIBs. We find that none of the C^-₇ bands match the DIBs in wavelength or expected profile. One of the DIBs (λ5748) attributed to C^-₇ is actually a stellar line. The two strongest DIBs attributed to C^-₇ (λ6270 and λ4964) are not correlated in strength, so they cannot share the same carrier. On the whole, we find no evidence supporting the hypothesis that C^-₇ is a carrier of the DIBs.

Original language	English (US)
Pages (from-to)	L49-L53
Journal	Astrophysical Journal
Volume	559
Issue number	1 PART 2
DOIs	https://doi.org/10.1086/323669
State	Published - Sep 20 2001
Externally published	Yes

Keywords

ISM: molecules
Line: identification
Methods: laboratory
Molecular data

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

Online availability

10.1086/323669

Library availability

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Cite this

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title = "Rejection of the C-7 diffuse interstellar band hypothesis",

abstract = "Using the new high-resolution (∼8 km s-1) echelle spectrograph on the 3.5 m telescope at the Apache Point Observatory, we have begun a high-sensitivity survey of the diffuse interstellar bands (DIBs) in a large sample of reddened stars. Now that we are 2 years into this long-term survey, our sample includes over 20 reddened stars that show at least one of the DIBs that had been suggested to be caused by C-7, based on the gas-phase measurement of the C-7 spectrum by J. P. Maier's group. The high-quality astronomical data from this larger sample of stars, along with the spectroscopic constants from the new laboratory work recently reported by Maier's group, have enabled us to examine more carefully the agreement between C-7 and the DIBs. We find that none of the C-7 bands match the DIBs in wavelength or expected profile. One of the DIBs (λ5748) attributed to C-7 is actually a stellar line. The two strongest DIBs attributed to C-7 (λ6270 and λ4964) are not correlated in strength, so they cannot share the same carrier. On the whole, we find no evidence supporting the hypothesis that C-7 is a carrier of the DIBs.",

keywords = "ISM: molecules, Line: identification, Methods: laboratory, Molecular data",

author = "McCall, {B. J.} and J. Thorburn and Hobbs, {L. M.} and T. Oka and York, {D. G.}",

note = "Funding Information: providing their laboratory data in advance of publication and P. Thaddeus for helpful comments on an early version of the manuscript. This work is based on observations obtained with the Apache Point Observatory 3.5 m telescope, which is owned and operated by the Astrophysical Research Consortium. This work has made use of the NASA Astrophysics Data Service as well as the SIMBAD database at the Centre de Donn{\'e}es Astronomiques de Strasbourg. This work has been supported by NSF grant PHY 97-22691 and NASA grant NAG5-4070. B. J. M. has been supported by the Fannie and John Hertz Foundation.",

year = "2001",

month = sep,

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doi = "10.1086/323669",

language = "English (US)",

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T1 - Rejection of the C-7 diffuse interstellar band hypothesis

AU - McCall, B. J.

AU - Thorburn, J.

AU - Hobbs, L. M.

AU - Oka, T.

AU - York, D. G.

N1 - Funding Information: providing their laboratory data in advance of publication and P. Thaddeus for helpful comments on an early version of the manuscript. This work is based on observations obtained with the Apache Point Observatory 3.5 m telescope, which is owned and operated by the Astrophysical Research Consortium. This work has made use of the NASA Astrophysics Data Service as well as the SIMBAD database at the Centre de Données Astronomiques de Strasbourg. This work has been supported by NSF grant PHY 97-22691 and NASA grant NAG5-4070. B. J. M. has been supported by the Fannie and John Hertz Foundation.

PY - 2001/9/20

Y1 - 2001/9/20

N2 - Using the new high-resolution (∼8 km s-1) echelle spectrograph on the 3.5 m telescope at the Apache Point Observatory, we have begun a high-sensitivity survey of the diffuse interstellar bands (DIBs) in a large sample of reddened stars. Now that we are 2 years into this long-term survey, our sample includes over 20 reddened stars that show at least one of the DIBs that had been suggested to be caused by C-7, based on the gas-phase measurement of the C-7 spectrum by J. P. Maier's group. The high-quality astronomical data from this larger sample of stars, along with the spectroscopic constants from the new laboratory work recently reported by Maier's group, have enabled us to examine more carefully the agreement between C-7 and the DIBs. We find that none of the C-7 bands match the DIBs in wavelength or expected profile. One of the DIBs (λ5748) attributed to C-7 is actually a stellar line. The two strongest DIBs attributed to C-7 (λ6270 and λ4964) are not correlated in strength, so they cannot share the same carrier. On the whole, we find no evidence supporting the hypothesis that C-7 is a carrier of the DIBs.

AB - Using the new high-resolution (∼8 km s-1) echelle spectrograph on the 3.5 m telescope at the Apache Point Observatory, we have begun a high-sensitivity survey of the diffuse interstellar bands (DIBs) in a large sample of reddened stars. Now that we are 2 years into this long-term survey, our sample includes over 20 reddened stars that show at least one of the DIBs that had been suggested to be caused by C-7, based on the gas-phase measurement of the C-7 spectrum by J. P. Maier's group. The high-quality astronomical data from this larger sample of stars, along with the spectroscopic constants from the new laboratory work recently reported by Maier's group, have enabled us to examine more carefully the agreement between C-7 and the DIBs. We find that none of the C-7 bands match the DIBs in wavelength or expected profile. One of the DIBs (λ5748) attributed to C-7 is actually a stellar line. The two strongest DIBs attributed to C-7 (λ6270 and λ4964) are not correlated in strength, so they cannot share the same carrier. On the whole, we find no evidence supporting the hypothesis that C-7 is a carrier of the DIBs.

KW - ISM: molecules

KW - Line: identification

KW - Methods: laboratory

KW - Molecular data

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