Abstract
Mid-infrared emission spectra, obtained from ISO archive, of thirteen astrophysical objects as well as computed spectra of 27 polycyclic aromatic hydrocarbon (PAH) molecules are studied. All the objects show strong aromatic infrared band (AIB) features with variations that correlate with object type. Based on AIB peak positions, the features for IRC \(+\)10216, Monoceros R2, and IC 5117 and PN-SwSt 1 are classified as type ‘A’, ‘B’ or ‘C’ for the first time. The AIBs at 6.2, 7.7 and 11.2 \(\mu \hbox {m}\) are used to obtain band intensity ratios for 6.2/7.7 and 11.2/6.2, which respectively indicate PAH size as number of carbon atoms and the ionization conditions of the medium. The smaller value of 6.2/7.7 points towards the presence of large PAH molecules, while higher value of 11.2/6.2 ratio relates to harsh conditions around the object. In general, for star-forming regions, the 6.2/7.7 band ratio obtained is >1 and the 11.2/6.2 ratio is >2, while for late type carbon stars, these values are <1 and <2. This indicates that small/medium-sized ionized PAHs are likely in star-forming regions and large PAHs in evolved stars. For each of the 27 plain PAH molecules, the integrated intensity in these bands is obtained from the computed infrared spectra and the band ratios are calculated. The ratio 6.2/7.7 in several computed medium and large sized PAH cations is in the range of observed ratio in most objects, but some molecules show large variations in band ratios, indicating that PAHs possible in interstellar medium could be more complex and with irregular structures.
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Allamandola L. J., Tielens A. G. G. M., Barker J. R. 1989, The Astrophysical Journal Supplement Series 71, 733, https://doi.org/10.1086/191396
Bauschlicher C. W., Ricca A., Boersma C., Allamandola L. J. 2018, The Astrophysical Journal Supplement Series 234, 32, https://doi.org/10.3847/1538-4365/aaa019
Berné O., Fuente A., Goicoechea J. R., et al. 2009, The Astrophysical Journal Letter 706, L160, https://doi.org/10.1088/0004-637X/706/1/L160, arXiv:0910.3935
Boersma C., Hony S., Tielens A. G. G. M. 2006, Astronomy & Astrophysics 447, 213, https://doi.org/10.1051/0004-6361:20053904
Bregman J. D. 1989, Observations of HII regions and planetary nebulae: The infrared emission bands. In: Interstellar Dust (Netherlands: Springer) p. 109, https://doi.org/10.1007/978-94-009-2462-8_9
Cherchneff I., Barker J. R., Tielens A. G. G. M. 1992, The Astrophysical Journal 401, 269, https://doi.org/10.1086/172059
Cohen M., Tielens A. G. G. M., Bregman J., et al. 1989, The Astrophysical Journal 341, 246, https://doi.org/10.1086/167489
de Graauw T., Haser L. N., Beintema D. A., et al. 1996, Astronomy & Astrophysics 315, L49
van Diedenhoven B., Peeters E., Kerckhoven C. V., et al. 2004, The Astrophysical Journal 611, 928, https://doi.org/10.1086/422404
Draine B. T., Li A. 2001, The Astrophysical Journal 551, 807, https://doi.org/10.1086/320227, arXiv:astro-ph/0011318
Hony S., Van Kerckhoven C., Peeters E., et al. 2001, Astronomy & Astrophysics 370, 1030, https://doi.org/10.1051/0004-6361:20010242, arXiv:astro-ph/0103035
Hsia C. H., Zhang Y., Kwok S., Chau W. 2019, Astrophysics and Space Science 364, 32, https://doi.org/10.1007/s10509-019-3523-2, arXiv:1902.08851
Langhoff S. R. 1996, The Journal of Physical Chemistry 100, 2819, https://doi.org/10.1021/jp952074g,
Maddalena R. J., Morris M., Moscowitz J., Thaddeus P. 1986, The Astrophysical Journal 303, 375, https://doi.org/10.1086/164083
Marco O. D., Soker N. 2002, Publications of the Astronomical Society of the Pacific 114, 602, https://doi.org/10.1086/341691
Maurya A., Rastogi S. 2015, Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 151, 1, https://doi.org/10.1016/j.saa.2015.06.069, http://www.sciencedirect.com/science/article/pii/S1386142515300093
Micelotta E. R., Jones A. P., Tielens A. G. G. M. 2010a, Astronomy & Astrophysics 510, A37, https://doi.org/10.1051/0004-6361/200911683, arXiv:0912.1595
Micelotta E. R., Jones A. P., Tielens A. G. G. M. 2010b, Astronomy & Astrophysics 510, A36, https://doi.org/10.1051/0004-6361/200911682, arXiv:0910.2461
Pathak A., Rastogi S. 2005, Theoretical IR spectra of large PAHs in study of UIR features. In: eds Lis D. C., Blake G. A., Herbst E. Astrochemistry: Recent Successes and Current Challenges, IAU Symposium, Vol. 231, p. 72
Pathak A., Rastogi S. 2006, Theoretical spectra of PAHs in modeling astrophysical IR features. In: 36th COSPAR Scientific Assembly, Vol. 36, p. 432
Pathak A., Rastogi S. 2007, Advances in Space Research 40, 1620, https://doi.org/10.1016/j.asr.2007.08.011
Pathak A., Rastogi S. 2008, Astronomy & Astrophysics 485, 735, https://doi.org/10.1051/0004-6361:20066618, arXiv:0804.2555
Peeters E., Hony S., Van Kerckhoven C., et al. 2002, Astronomy & Astrophysics, 390, 1089, https://doi.org/10.1051/0004-6361:20020773, arXiv:astro-ph/0205400
Pino T., Chabot M., Béroff K., et al. 2019, Astronomy & Astrophysics 623, A134, https://doi.org/10.1051/0004-6361/201834855
Pottasch S. R., Beintema D. A. 1999, Astronomy & Astrophysics 347, 975
Rastogi S., Pathak A., Maurya A. 2013, AIP Conference Proceedings 1543, 49, https://doi.org/10.1063/1.4812599,
Rigopoulou D., Barale M., Clary D. C., et al. 2021, Monthly Notices of the Royal Astronomical Society 504, 5287, https://doi.org/10.1093/mnras/stab959, https://academic.oup.com/mnras/article-pdf/504/4/5287/37975308/stab959.pdf
Sloan G. C., Kraemer K. E., Price S. D., Shipman R. F. 2003, The Astrophysical Journal Supplement Series 147, 379, https://doi.org/10.1086/375443
Stock D. J., Peeters E. 2017 Astrophysical Journal 837, 129, https://doi.org/10.3847/1538-4357/aa5f54
Stock D. J., Choi W. D. Y., Moya L. G. V, et al. 2016, Astrophysical Journal 819, 65, https://doi.org/10.3847/0004-637X/819/1/65
Szczerba R., Górny S. K., Stasińska G., Siódmiak N., Tylenda R. 2001, Astrophysics and Space Science 275, 113
Tielens A. 2008, Annual Review of Astronomy and Astrophysics 46, 289, https://doi.org/10.1146/annurev.astro.46.060407.145211
Tielens A. G. G. M. 2013, Reviews of Modern Physics 85, 1021, https://doi.org/10.1103/RevModPhys.85.1021
Van de Sande M., Sundqvist J. O., Millar T. J., Keller D., Decin L. 2019, The chemistry in clumpy AGB outflows. In: eds Kerschbaum F., Groenewegen M., Olofsson H., IAU Symposium, IAU Symposium, Vol. 343, p. 531, https://doi.org/10.1017/S1743921318005434
Wada S., Onaka T., Yamamura I., Murata Y., Tokunaga A. T. 2003, Astronomy & Astrophysics 407, 551, https://doi.org/10.1051/0004-6361:20030881, arXiv:astro-ph/0306309
Zang R. X., Maragkoudakis A., Peeters E. 2022, Monthly Notices of the Royal Astronomical Society, 511, 5142, https://doi.org/10.1093/mnras/stac214, https://academic.oup.com/mnras/article-pdf/511/4/5142/42699883/stac214.pdf
Acknowledgements
This work is conducted under MoU between ARIES, Nainital and DDU Gorakhpur University. RKA acknowledges financial support from University Grants Commission, New Delhi, under the Rajiv Gandhi National Fellowship scheme.
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This article is part of the Special Issue on “Star formation studies in the context of NIR instruments on 3.6m DOT”.
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Anand, R.K., Rastogi, S. & Kumar, B. PAH emission features in star-forming regions and late type stars. J Astrophys Astron 44, 47 (2023). https://doi.org/10.1007/s12036-023-09941-z
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DOI: https://doi.org/10.1007/s12036-023-09941-z