ItemArticle

Polycyclic Aromatic Hydrocarbons in the Circumstellar Medium of Herbig Ae/Be Stars

Title
Polycyclic Aromatic Hydrocarbons in the Circumstellar Medium of Herbig Ae/Be Stars
Creator
Arun, Roy; Mathew, Blesson; Shridharan, Baskaran; Ujjwal, Krishnan; Akhil, Krishna R; Gopinathan, Maheswar; Kartha, Sreeja S.
Description
We present a comprehensive mid-infrared spectroscopic survey of 124 Herbig Ae/Be stars using newly processed Spitzer/IRS spectra from the newly released CASSISjuice database. Based on prominent dust and molecular signatures (polycyclic aromatic hydrocarbons (PAHs), silicates, and hydrogenated amorphous carbons), we classify the stars into five groups. Our analysis reveals that 64% of the spectra show PAH emission, with detections peaking in the stellar effective temperature range 7000-11,000 K (B9-A5). Silicate features appear in 50% of the sample and likewise diminish at higher temperatures. Additionally, we find that future PAH studies can focus on Herbig Ae/Be stars with a spectral index n2?24 > ?1 and flared morphologies to maximize PAH detections. The 6.2 ?m PAH band is the most frequently observed in our sample, shifting blueward with increasing stellar temperature, and this is the largest sample yet used to test that peak shift. The weaker 6.0 ?m feature does not shift with 6.2 ?m, implying a distinct origin of C=O (carbonyl) or olefinic C=C stretching relative to C-C vibrations. We examined the 11.0/11.2 ?m PAH ratio using high-resolution Spitzer spectra for the first time in a sample of Herbig Ae/Be stars, finding a range of ionization conditions. This study provides a strong foundation for future JWST observations of intermediate-mass pre-main-sequence stars. 2025. National Astronomical Observatories, CAS and IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.
Source
Research in Astronomy and Astrophysics;Volume;25;Issue;9;Article No.;95005;
Date
01-01-2025
Publisher
Institute of Physics
Subject
astrochemistry; catalogs; stars: variables: T Tauri, Herbig Ae/Be; techniques: spectroscopic
Coverage
Arun R., Indian Institute of Astrophysics, Sarjapur Road, Koramangala, Bangalore, 560034, India; Mathew B., Center of Excellence in Astronomy and Astrophysics, Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore, 560029, India; Shridharan B., Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai, 400005, India; Ujjwal K., Center of Excellence in Astronomy and Astrophysics, Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore, 560029, India; Akhil K.R., Center of Excellence in Astronomy and Astrophysics, Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore, 560029, India; Gopinathan M., Indian Institute of Astrophysics, Sarjapur Road, Koramangala, Bangalore, 560034, India; Kartha S.S., Center of Excellence in Astronomy and Astrophysics, Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore, 560029, India
Rights
Restricted Access; Hardcopy may be available in the library
Relation
ISSN: 16744527;
Format
online
Language
English
Type
Article

Citation

Arun, Roy; Mathew, Blesson; Shridharan, Baskaran; Ujjwal, Krishnan; Akhil, Krishna R; Gopinathan, Maheswar; Kartha, Sreeja S., “Polycyclic Aromatic Hydrocarbons in the Circumstellar Medium of Herbig Ae/Be Stars,” CHRIST (Deemed To Be University) Institutional Repository, accessed June 19, 2026, https://archives.christuniversity.in/items/show/22808.

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