CO 1st overtone spectra of cool evolved stars: Diagnostics for hydrodynamic atmosphere models

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Abstract

We present spectra covering the wavelength range 2.28 to 2.36 μm at a resolution of Δλ = 0.0007 μm (or R = 3500) for a sample of 24 cool evolved stars. The sample comprises 8 M supergiants, 5 M giants, 3 S stars, 6 carbon stars, and 2 RV Tauri variables. The wavelengths covered include the main parts of the 12C16O v = 2-0 and 3-1 overtone bands, as well as the v = 4-2 and 13CO v = 2-0 bandhead regions. CO lines dominate the spectrum for all the stars observed, and at this resolution most of the observed features can be identified with individual CO R- or P-branch lines or blends. The observed transitions arise from a wide range of energy levels extending from the ground state to E/k > 20 000 K. We looked for correlations between the intensities of various CO absorption line features and other stellar properties, including IR colors and mass loss rates. Two useful CO line features are the v = 2-0 R14 line, and the CO v = 2-0 bandhead. The intensity of the 2-0 bandhead shows a trend with K-[12] color such that the reddest stars (K-[12] > 3 mag) exhibit a wide range in 2-0 bandhead depth, while the least reddened have the deepest 2-0 bandheads, with a small range of variation from star to star. Gas mass loss rates for both the AGB stars and the red supergiants in our sample correlate with the K-[12] color, consistent with other studies. The data imply that stars with Mgas < 5 × 10-7 M y-1 exhibit a much narrower range in the relative strengths of CO 2-0 band features than stars with higher mass loss rates. The range in observed spectral properties implies that there are significant differences in atmospheric structure among the stars in this sample.

Original languageEnglish (US)
Pages (from-to)965-981
Number of pages17
JournalAstronomy and Astrophysics
Volume384
Issue number3
StatePublished - Mar 2002

Fingerprint

cool stars
hydrodynamics
harmonics
atmospheres
stars
atmosphere
wavelength
atmospheric structure
color
S stars
carbon
carbon stars
gas
asymptotic giant branch stars
energy
loss
rate
wavelengths
coverings
energy levels

Keywords

  • Infrared: stars
  • Stars: AGB and post-AGB
  • Stars: atmospheres
  • Stars: supergiants

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

@article{eb51b6f3ccb3495c82dc8831b3cd106f,
title = "CO 1st overtone spectra of cool evolved stars: Diagnostics for hydrodynamic atmosphere models",
abstract = "We present spectra covering the wavelength range 2.28 to 2.36 μm at a resolution of Δλ = 0.0007 μm (or R = 3500) for a sample of 24 cool evolved stars. The sample comprises 8 M supergiants, 5 M giants, 3 S stars, 6 carbon stars, and 2 RV Tauri variables. The wavelengths covered include the main parts of the 12C16O v = 2-0 and 3-1 overtone bands, as well as the v = 4-2 and 13CO v = 2-0 bandhead regions. CO lines dominate the spectrum for all the stars observed, and at this resolution most of the observed features can be identified with individual CO R- or P-branch lines or blends. The observed transitions arise from a wide range of energy levels extending from the ground state to E/k > 20 000 K. We looked for correlations between the intensities of various CO absorption line features and other stellar properties, including IR colors and mass loss rates. Two useful CO line features are the v = 2-0 R14 line, and the CO v = 2-0 bandhead. The intensity of the 2-0 bandhead shows a trend with K-[12] color such that the reddest stars (K-[12] > 3 mag) exhibit a wide range in 2-0 bandhead depth, while the least reddened have the deepest 2-0 bandheads, with a small range of variation from star to star. Gas mass loss rates for both the AGB stars and the red supergiants in our sample correlate with the K-[12] color, consistent with other studies. The data imply that stars with Mgas < 5 × 10-7 M⊙ y-1 exhibit a much narrower range in the relative strengths of CO 2-0 band features than stars with higher mass loss rates. The range in observed spectral properties implies that there are significant differences in atmospheric structure among the stars in this sample.",
keywords = "Infrared: stars, Stars: AGB and post-AGB, Stars: atmospheres, Stars: supergiants",
author = "Bieging, {John H} and Rieke, {Marcia J} and Rieke, {George H.}",
year = "2002",
month = "3",
language = "English (US)",
volume = "384",
pages = "965--981",
journal = "Astronomy and Astrophysics",
issn = "0004-6361",
publisher = "EDP Sciences",
number = "3",

}

TY - JOUR

T1 - CO 1st overtone spectra of cool evolved stars

T2 - Diagnostics for hydrodynamic atmosphere models

AU - Bieging, John H

AU - Rieke, Marcia J

AU - Rieke, George H.

PY - 2002/3

Y1 - 2002/3

N2 - We present spectra covering the wavelength range 2.28 to 2.36 μm at a resolution of Δλ = 0.0007 μm (or R = 3500) for a sample of 24 cool evolved stars. The sample comprises 8 M supergiants, 5 M giants, 3 S stars, 6 carbon stars, and 2 RV Tauri variables. The wavelengths covered include the main parts of the 12C16O v = 2-0 and 3-1 overtone bands, as well as the v = 4-2 and 13CO v = 2-0 bandhead regions. CO lines dominate the spectrum for all the stars observed, and at this resolution most of the observed features can be identified with individual CO R- or P-branch lines or blends. The observed transitions arise from a wide range of energy levels extending from the ground state to E/k > 20 000 K. We looked for correlations between the intensities of various CO absorption line features and other stellar properties, including IR colors and mass loss rates. Two useful CO line features are the v = 2-0 R14 line, and the CO v = 2-0 bandhead. The intensity of the 2-0 bandhead shows a trend with K-[12] color such that the reddest stars (K-[12] > 3 mag) exhibit a wide range in 2-0 bandhead depth, while the least reddened have the deepest 2-0 bandheads, with a small range of variation from star to star. Gas mass loss rates for both the AGB stars and the red supergiants in our sample correlate with the K-[12] color, consistent with other studies. The data imply that stars with Mgas < 5 × 10-7 M⊙ y-1 exhibit a much narrower range in the relative strengths of CO 2-0 band features than stars with higher mass loss rates. The range in observed spectral properties implies that there are significant differences in atmospheric structure among the stars in this sample.

AB - We present spectra covering the wavelength range 2.28 to 2.36 μm at a resolution of Δλ = 0.0007 μm (or R = 3500) for a sample of 24 cool evolved stars. The sample comprises 8 M supergiants, 5 M giants, 3 S stars, 6 carbon stars, and 2 RV Tauri variables. The wavelengths covered include the main parts of the 12C16O v = 2-0 and 3-1 overtone bands, as well as the v = 4-2 and 13CO v = 2-0 bandhead regions. CO lines dominate the spectrum for all the stars observed, and at this resolution most of the observed features can be identified with individual CO R- or P-branch lines or blends. The observed transitions arise from a wide range of energy levels extending from the ground state to E/k > 20 000 K. We looked for correlations between the intensities of various CO absorption line features and other stellar properties, including IR colors and mass loss rates. Two useful CO line features are the v = 2-0 R14 line, and the CO v = 2-0 bandhead. The intensity of the 2-0 bandhead shows a trend with K-[12] color such that the reddest stars (K-[12] > 3 mag) exhibit a wide range in 2-0 bandhead depth, while the least reddened have the deepest 2-0 bandheads, with a small range of variation from star to star. Gas mass loss rates for both the AGB stars and the red supergiants in our sample correlate with the K-[12] color, consistent with other studies. The data imply that stars with Mgas < 5 × 10-7 M⊙ y-1 exhibit a much narrower range in the relative strengths of CO 2-0 band features than stars with higher mass loss rates. The range in observed spectral properties implies that there are significant differences in atmospheric structure among the stars in this sample.

KW - Infrared: stars

KW - Stars: AGB and post-AGB

KW - Stars: atmospheres

KW - Stars: supergiants

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M3 - Article

AN - SCOPUS:0036500957

VL - 384

SP - 965

EP - 981

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

SN - 0004-6361

IS - 3

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