JWST: Deuterated PAHs, PAH-nitriles, and PAH Overtone and Combination Bands I: Program Description and First Look
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| Autores principales: | , , , , , , , , |
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| Formato: | Preprint |
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2023
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| author | Boersma, C. Allamandola, L. J. Esposito, V. J. Maragkoudakis, A. Bregman, J. D. Temi, P. Lee, T. J. Fortenberry, R. C. Peeters, E. |
| author_facet | Boersma, C. Allamandola, L. J. Esposito, V. J. Maragkoudakis, A. Bregman, J. D. Temi, P. Lee, T. J. Fortenberry, R. C. Peeters, E. |
| contents | A first look is taken at the NIRSpec 1-5 $μ$m observations from JWST program 1591 that targets 7 objects along the low-mass stellar life cycle with PAH emission. Spectra extracted from a 1.5$^{\prime\prime}$ radius sized circular aperture are explored, showing a wealth of features, including the 3 $μ$m PAH complex, the PAH-continuum, and atomic and molecular emission lines from HI, He, H$_{\rm 2}$, and other species. CO$_{\rm 2}$- and H$_{\rm 2}$O-ice absorption and CO emission is also seen. Focusing on the bright-PDR position in M17, the PAH CH stretch falls at 3.29 $μ$m (FWHM=0.04 $μ$m). Signs of its 1.68 $μ$m overtone are confused by line emission in all targets. Multi-component decomposition reveals a possible aliphatic deuterated PAH feature centered at 4.65 $μ$m (FWHM=0.02 $μ$m), giving [D/H]$_{\rm alip.}$=31$\pm$12.7%. However, there is little sign of its aromatic counterpart between 4.36-4.43 $μ$m. There is also little sign of PAH-nitrile emission between 4.34-4.39 $μ$m. A PAH continuum rises from $\sim$1 to 3.2 $μ$m, after which it jumps by about a factor of 2.5 at 3.6 $μ$m, with bumps at 3.8, 4.04, and 4.34 $μ$m adding structure. The CO$_{\rm 2}$ absorption band in M17 is matched with 10:1 H$_{\rm 2}$O:CO$_{\rm 2}$ ice at 10 K. The $v$=0 pure rotational molecular hydrogen population diagram reveals $>$2200 K UV-pumped gas. The hydrogen Pfund series runs from levels 10 to $>$30. Considering Br$α$/Br$β$=0.381$\pm$0.01966 and Case B recombination results in A$_{\rm V}{\simeq}$8. CO emission in IRAS21282+5050 originates from 258 K gas. In-depth spectral-spatial analysis of all features and targets are planned for a series of forthcoming papers. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2310_05774 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | JWST: Deuterated PAHs, PAH-nitriles, and PAH Overtone and Combination Bands I: Program Description and First Look Boersma, C. Allamandola, L. J. Esposito, V. J. Maragkoudakis, A. Bregman, J. D. Temi, P. Lee, T. J. Fortenberry, R. C. Peeters, E. Astrophysics of Galaxies Solar and Stellar Astrophysics A first look is taken at the NIRSpec 1-5 $μ$m observations from JWST program 1591 that targets 7 objects along the low-mass stellar life cycle with PAH emission. Spectra extracted from a 1.5$^{\prime\prime}$ radius sized circular aperture are explored, showing a wealth of features, including the 3 $μ$m PAH complex, the PAH-continuum, and atomic and molecular emission lines from HI, He, H$_{\rm 2}$, and other species. CO$_{\rm 2}$- and H$_{\rm 2}$O-ice absorption and CO emission is also seen. Focusing on the bright-PDR position in M17, the PAH CH stretch falls at 3.29 $μ$m (FWHM=0.04 $μ$m). Signs of its 1.68 $μ$m overtone are confused by line emission in all targets. Multi-component decomposition reveals a possible aliphatic deuterated PAH feature centered at 4.65 $μ$m (FWHM=0.02 $μ$m), giving [D/H]$_{\rm alip.}$=31$\pm$12.7%. However, there is little sign of its aromatic counterpart between 4.36-4.43 $μ$m. There is also little sign of PAH-nitrile emission between 4.34-4.39 $μ$m. A PAH continuum rises from $\sim$1 to 3.2 $μ$m, after which it jumps by about a factor of 2.5 at 3.6 $μ$m, with bumps at 3.8, 4.04, and 4.34 $μ$m adding structure. The CO$_{\rm 2}$ absorption band in M17 is matched with 10:1 H$_{\rm 2}$O:CO$_{\rm 2}$ ice at 10 K. The $v$=0 pure rotational molecular hydrogen population diagram reveals $>$2200 K UV-pumped gas. The hydrogen Pfund series runs from levels 10 to $>$30. Considering Br$α$/Br$β$=0.381$\pm$0.01966 and Case B recombination results in A$_{\rm V}{\simeq}$8. CO emission in IRAS21282+5050 originates from 258 K gas. In-depth spectral-spatial analysis of all features and targets are planned for a series of forthcoming papers. |
| title | JWST: Deuterated PAHs, PAH-nitriles, and PAH Overtone and Combination Bands I: Program Description and First Look |
| topic | Astrophysics of Galaxies Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2310.05774 |