Discovery of fullerenes in the shell of candidate luminous blue variable WRAY 16-232
subject: astrochemistry; circumstellar matter; infrared: stars; stars: variables: general; stars: winds, outflows
description: We report the discovery of fullerene in the circumstellar environment of WRAY 16-232, a strong candidate luminous blue variable. Multiple pointings of archival Spitzer Infrared Spectrograph spectra reveal, for the first time, the presence of prominent vibrational bands of C60 at 17.4 and 18.9 ?m in a luminous blue variable (LBV) envelope, along with the strong polycyclic aromatic hydrocarbon features. These observations suggest that, despite the harsh radiative conditions, large carbonaceous molecules can form, process, and survive in the ejecta of massive stars. Complementary optical spectroscopy with South African Large Telescope High-Resolution Spectrograph shows multiple P Cygni profiles in H ?, He i, and Fe ii lines, which are indicative of a dense, expanding wind and substantial mass-loss. Furthermore, analysis of decade long photometric data shows short-term brightness variations of ?0.5 mag. These results not only reinforce the classification of WRAY 16-232 as a strong LBV candidate but also provide new insights into the mechanisms of dust formation and the chemical enrichment of the interstellar medium by massive stars. We discuss various scenarios for fullerene formation in such environments, and find that shock processing due to wind-wind interactions could be playing a vital role. The shell of WRAY 16-232 has an ideal UV field strength and the time-scales appear to match with shock processing time-scales. The results highlight the need for further high spatial/spectral resolution and temporal observations to confirm the formation and survival scenario of C60 in its shell. The Author(s) 2025. Published by Oxford University Press on behalf of Royal Astronomical Society.
creator: Arun, R.; Prasoon, S.A.; Mathew, Blesson; Akhila, D.; Banerjee, Gourav; Shridharan, B.; Maheswar, G.; Surya, Arun
source: Monthly Notices of the Royal Astronomical Society;Volume;543;Issue;4;pp.3214-3228
publisher: Oxford University Press
date: 01-01-2025
rights: All Open Access; Gold Open Access
relation: ISSN: 358711; CODEN: MNRAA
format: online
language: English
type: Article
coverage: Arun R., Indian Institute of Astrophysics, Sarjapur Road, Koramangala, Bangalore, 560034, India; Prasoon S.A., Indian Institute of Astrophysics, Sarjapur Road, Koramangala, Bangalore, 560034, India, Center of Excellence in Astronomy and Astrophysics, Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore, 560029, India; Mathew B., Center of Excellence in Astronomy and Astrophysics, Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore, 560029, India; Akhila D., Center of Excellence in Astronomy and Astrophysics, Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore, 560029, India, Instituto de Astronom y Ciencias Planetarias, Universidad de Atacama, Copayapu 485, Copiap Chile; Banerjee G., Indian Institute of Astrophysics, Sarjapur Road, Koramangala, Bangalore, 560034, India; Shridharan B., Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai, 400005, India; Maheswar G., Indian Institute of Astrophysics, Sarjapur Road, Koramangala, Bangalore, 560034, India; Surya A., Indian Institute of Astrophysics, Sarjapur Road, Koramangala, Bangalore, 560034, India