Mid-infrared spectra of polycyclic aromatic hydrocarbon emission in herbig Ae/Be stars

Ciska Kemper; G. C. Sloan; L. D. Keller; W. J. Forrest; E. Leibensperger; B. Sargent; A. Li; J. Najita; D. M. Watson; B. R. Brandl; C. H. Chen; J. D. Green; F. Markwick-Kemper; T. L. Herter; P. D'Alessio; P. W. Morris; D. J. Barry; P. Hall; P. C. Myers; J. R. Houck

doi:10.1086/444371

Mid-infrared spectra of polycyclic aromatic hydrocarbon emission in herbig Ae/Be stars

Ciska Kemper, G. C. Sloan, L. D. Keller, W. J. Forrest, E. Leibensperger, B. Sargent, A. Li, J. Najita, D. M. Watson, B. R. Brandl, C. H. Chen, J. D. Green, F. Markwick-Kemper, T. L. Herter, P. D'Alessio, P. W. Morris, D. J. Barry, P. Hall, P. C. Myers, J. R. Houck

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Abstract

We present spectra of four Herbig Ae/Be stars obtained with the Infrared Spectrograph (IRS) on the Spitzer Space Telescope. All four of the sources show strong emission from polycyclic aromatic hydrocarbons (PAHs), with the 6.2 μm emission feature shifted to 6.3 μm and the strongest C-C skeletal-mode feature occurring at 7.9 μm instead of at 7.7 μm, as is often seen. Remarkably, none of the four stars has silicate emission. The strength of the 7.9 μm feature varies with respect to the 11.3 μm feature among the sources, indicating that we have observed PAHs with a range of ionization fractions. The ionization fraction is higher for systems with hotter and brighter central stars. Two sources, HD 34282 and HD 169142, show emission features from aliphatic hydrocarbons at 6.85 and 7.25 μm. The spectrum of HD 141569 shows a previously undetected emission feature at 12.4 μm that may be related to the 12.7 μm PAH feature. The spectrum of HD 135344, the coolest star in our sample, shows an unusual profile in the 7-9 μm region, with the peak emission to the red of 8.0 μm and no 8.6 μm PAH feature. © 2005. The American Astronomical Society. All rights reserved.

Original language	English
Pages (from-to)	956-963
Number of pages	7
Journal	Astrophysical Journal
Volume	632
Issue number	2 I
DOIs	https://doi.org/10.1086/444371
Publication status	Published - 20 Oct 2005

Keywords

Infrared: stars
Stars: chemically peculiar

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10.1086/444371

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Kemper, C., Sloan, G. C., Keller, L. D., Forrest, W. J., Leibensperger, E., Sargent, B., Li, A., Najita, J., Watson, D. M., Brandl, B. R., Chen, C. H., Green, J. D., Markwick-Kemper, F., Herter, T. L., D'Alessio, P., Morris, P. W., Barry, D. J., Hall, P., Myers, P. C., & Houck, J. R. (2005). Mid-infrared spectra of polycyclic aromatic hydrocarbon emission in herbig Ae/Be stars. Astrophysical Journal, 632(2 I), 956-963. https://doi.org/10.1086/444371

@article{8685abd857ea4b8ca27e6926fee7b177,

title = "Mid-infrared spectra of polycyclic aromatic hydrocarbon emission in herbig Ae/Be stars",

abstract = "We present spectra of four Herbig Ae/Be stars obtained with the Infrared Spectrograph (IRS) on the Spitzer Space Telescope. All four of the sources show strong emission from polycyclic aromatic hydrocarbons (PAHs), with the 6.2 μm emission feature shifted to 6.3 μm and the strongest C-C skeletal-mode feature occurring at 7.9 μm instead of at 7.7 μm, as is often seen. Remarkably, none of the four stars has silicate emission. The strength of the 7.9 μm feature varies with respect to the 11.3 μm feature among the sources, indicating that we have observed PAHs with a range of ionization fractions. The ionization fraction is higher for systems with hotter and brighter central stars. Two sources, HD 34282 and HD 169142, show emission features from aliphatic hydrocarbons at 6.85 and 7.25 μm. The spectrum of HD 141569 shows a previously undetected emission feature at 12.4 μm that may be related to the 12.7 μm PAH feature. The spectrum of HD 135344, the coolest star in our sample, shows an unusual profile in the 7-9 μm region, with the peak emission to the red of 8.0 μm and no 8.6 μm PAH feature. {\textcopyright} 2005. The American Astronomical Society. All rights reserved.",

keywords = "Infrared: stars, Stars: chemically peculiar",

author = "Ciska Kemper and Sloan, {G. C.} and Keller, {L. D.} and Forrest, {W. J.} and E. Leibensperger and B. Sargent and A. Li and J. Najita and Watson, {D. M.} and Brandl, {B. R.} and Chen, {C. H.} and Green, {J. D.} and F. Markwick-Kemper and Herter, {T. L.} and P. D'Alessio and Morris, {P. W.} and Barry, {D. J.} and P. Hall and Myers, {P. C.} and Houck, {J. R.}",

year = "2005",

month = oct,

day = "20",

doi = "10.1086/444371",

language = "English",

volume = "632",

pages = "956--963",

journal = "Astrophysical Journal",

issn = "1538-4357",

publisher = "Institute of Physics Publishing, Inc",

number = "2 I",

}

Kemper, C, Sloan, GC, Keller, LD, Forrest, WJ, Leibensperger, E, Sargent, B, Li, A, Najita, J, Watson, DM, Brandl, BR, Chen, CH, Green, JD, Markwick-Kemper, F, Herter, TL, D'Alessio, P, Morris, PW, Barry, DJ, Hall, P, Myers, PC & Houck, JR 2005, 'Mid-infrared spectra of polycyclic aromatic hydrocarbon emission in herbig Ae/Be stars', Astrophysical Journal, vol. 632, no. 2 I, pp. 956-963. https://doi.org/10.1086/444371

TY - JOUR

T1 - Mid-infrared spectra of polycyclic aromatic hydrocarbon emission in herbig Ae/Be stars

AU - Kemper, Ciska

AU - Sloan, G. C.

AU - Keller, L. D.

AU - Forrest, W. J.

AU - Leibensperger, E.

AU - Sargent, B.

AU - Li, A.

AU - Najita, J.

AU - Watson, D. M.

AU - Brandl, B. R.

AU - Chen, C. H.

AU - Green, J. D.

AU - Markwick-Kemper, F.

AU - Herter, T. L.

AU - D'Alessio, P.

AU - Morris, P. W.

AU - Barry, D. J.

AU - Hall, P.

AU - Myers, P. C.

AU - Houck, J. R.

PY - 2005/10/20

Y1 - 2005/10/20

N2 - We present spectra of four Herbig Ae/Be stars obtained with the Infrared Spectrograph (IRS) on the Spitzer Space Telescope. All four of the sources show strong emission from polycyclic aromatic hydrocarbons (PAHs), with the 6.2 μm emission feature shifted to 6.3 μm and the strongest C-C skeletal-mode feature occurring at 7.9 μm instead of at 7.7 μm, as is often seen. Remarkably, none of the four stars has silicate emission. The strength of the 7.9 μm feature varies with respect to the 11.3 μm feature among the sources, indicating that we have observed PAHs with a range of ionization fractions. The ionization fraction is higher for systems with hotter and brighter central stars. Two sources, HD 34282 and HD 169142, show emission features from aliphatic hydrocarbons at 6.85 and 7.25 μm. The spectrum of HD 141569 shows a previously undetected emission feature at 12.4 μm that may be related to the 12.7 μm PAH feature. The spectrum of HD 135344, the coolest star in our sample, shows an unusual profile in the 7-9 μm region, with the peak emission to the red of 8.0 μm and no 8.6 μm PAH feature. © 2005. The American Astronomical Society. All rights reserved.

AB - We present spectra of four Herbig Ae/Be stars obtained with the Infrared Spectrograph (IRS) on the Spitzer Space Telescope. All four of the sources show strong emission from polycyclic aromatic hydrocarbons (PAHs), with the 6.2 μm emission feature shifted to 6.3 μm and the strongest C-C skeletal-mode feature occurring at 7.9 μm instead of at 7.7 μm, as is often seen. Remarkably, none of the four stars has silicate emission. The strength of the 7.9 μm feature varies with respect to the 11.3 μm feature among the sources, indicating that we have observed PAHs with a range of ionization fractions. The ionization fraction is higher for systems with hotter and brighter central stars. Two sources, HD 34282 and HD 169142, show emission features from aliphatic hydrocarbons at 6.85 and 7.25 μm. The spectrum of HD 141569 shows a previously undetected emission feature at 12.4 μm that may be related to the 12.7 μm PAH feature. The spectrum of HD 135344, the coolest star in our sample, shows an unusual profile in the 7-9 μm region, with the peak emission to the red of 8.0 μm and no 8.6 μm PAH feature. © 2005. The American Astronomical Society. All rights reserved.

KW - Infrared: stars

KW - Stars: chemically peculiar

U2 - 10.1086/444371

DO - 10.1086/444371

M3 - Article

SN - 1538-4357

VL - 632

SP - 956

EP - 963

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 2 I

ER -

Mid-infrared spectra of polycyclic aromatic hydrocarbon emission in herbig Ae/Be stars

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Keywords

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