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arXiv · 2204.13259

Detection of a broad 8 $μ$m UIR feature in the mid-infrared spectrum of WR 125 observed with Subaru/COMICS

Izumi Endo·Ryan M. Lau·Itsuki Sakon·Takashi Onaka·Peredur M. Williams·Victor I. Shenavrin
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Abstract

We present the detection of a broad 8 $μ$m feature in newly formed dust around the carbon-rich Wolf-Rayet (WC) binary WR 125 from N-band low-resolution (NL; R$\sim$250) spectroscopy between 7.3-13.6 $μ$m and N-band (11.7 $μ$m) and Q-band (18.8 $μ$m) imaging with Subaru/COMICS in 2019 October. WR 125 is a colliding wind binary (${\rm WC7+O9}$) that exhibited renewed dust formation starting in 2018, $\sim$28 years after its first dust formation episode had been observed. We also compare our infrared photometry with historical observations and revise the dust-formation period of WR 125 to 28.1 years. Archival infrared spectra of five dusty WC stars, WR 48a, WR 98a, WR 104, WR 112 and WR 118, obtained with ISO/SWS are reanalyzed and compared with the WR 125 spectrum to search for a similar feature. We analyze the dusty WC spectra using two different extinction curves to investigate the impact of interstellar extinction correction on the presence and/or properties of the 8 $μ$m feature. All of the dusty WC spectra dereddened with the two different extinction curves show a broad feature around 8 $μ$m (FWHM$\sim$1-2 $μ$m). We suggest that these 8 $μ$m features seen in the dusty WC spectra are related to the Class C unidentified infrared (UIR) features.

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Izumi Endo, Ryan M. Lau, Itsuki Sakon, Takashi Onaka, Peredur M. Williams, Victor I. Shenavrin. 2022-05-09. Detection of a broad 8 $μ$m UIR feature in the mid-infrared spectrum of WR 125 observed with Subaru/COMICS. https://doi.org/10.3847/1538-4357%2Fac63bd

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