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Название: Orion Bar as a Window to the Evolution of PAHs
Авторы: Murga, M. S.
Kirsanova, M. S.
Wiebe, D. S.
Boley, P. A.
Дата публикации: 2022
Издатель: Oxford University Press
Oxford University Press (OUP)
Библиографическое описание: Orion Bar as a Window to the Evolution of PAHs / M. S. Murga, M. S. Kirsanova, D. S. Wiebe et al. — DOI 10.2495/EQ140151 // Monthly Notices of the Royal Astronomical Society. — 2022. — Vol. 509. — Iss. 1. — P. 800-817.
Аннотация: We investigate the mid-infrared (IR) emission in the Orion Bar photodissociation region (PDR), using archival photometric and spectroscopic observations from the United Kingdom Infrared Telescope (UKIRT), Spitzer, Infrared Space Observatory(ISO), and Stratospheric Observatory for Infrared Astronomy (SOFIA) telescopes. Specifically, we consider flux densities of the emission bands at 3.3, 3.4, 3.6, 6.6, 7.7, and 11.2 $$m in several locations and a spectrum from 3 to 45 $$m in one location. We study the behaviour of band flux ratios, which are sensitive to external conditions, as revealed by their variations with the distance from an ionizing source. Assuming that the mid-IR emission arises mostly from polycyclic aromatic hydrocarbons (PAHs), and that a weak emission feature at 3.4 $$m is related to PAHs with extra hydrogen atoms (H-PAHs), we trace variations of the ratios using a model for PAH evolution. Namely, we estimate how populations of PAHs of different sizes, hydrogenation and ionization states change across the Orion Bar over a time interval approximately equal to its lifetime. The obtained ensembles of PAHs are further used to calculate the corresponding synthetic spectra and band flux densities. The model satisfactorily describes the main features of the ratios I3.6/I11.2, I7.7/I11.2, I7.7/I3.6, and I3.3/I3.4. We conclude that the best coincidence between modelling and observations is achieved if C loss of PAHs is limited by the number of carbon atoms NC = 60, and the band at 3.4 $$m may indeed be attributed to H-PAHs. We confi that large cations dominate at the surface of the PDR but small neutral PAHs and anions are abundant deeper in the molecular cloud. © 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
Ключевые слова: ASTROCHEMISTRY
EVOLUTION
INDIVIDUAL OBJECTS
INFRARED
ISM
LINES AND BANDS
ORION BAR
ATOMS
OBSERVATORIES
TELESCOPES
MID-INFRARED EMISSION
POLYCYCLIC AROMATIC HYDROCARBONS
URI: http://elar.urfu.ru/handle/10995/111382
Условия доступа: info:eu-repo/semantics/openAccess
Идентификатор РИНЦ: 47541694
Идентификатор SCOPUS: 85121211757
Идентификатор WOS: 000741326000054
Идентификатор PURE: 29143037
ISSN: 0035-8711
DOI: 10.1093/mnras/stab3061
Располагается в коллекциях:Научные публикации ученых УрФУ, проиндексированные в SCOPUS и WoS CC

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