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arXiv · 2306.11945

IRAS 00450+7401 and the mid-infrared fade/burst cycle of R Coronae Borealis-type stars

William A. Burris·Carl Melis·Allen W. Shafter·Georgia V. Panopoulou·Edward L. Wright·John Della Costa
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Abstract

We present optical and infrared imaging and spectroscopy of the R Coronae Borealis-type (R Cor Bor) star IRAS 00450+7401. Optical spectra further confirm its classification as a cool R Cor Bor system, having a hydrogen-deficient carbon star spectral sub-class of HdC5 or later. Mid-infrared spectroscopy reveals the typical ~8 um ``hump'' seen in other R Cor Bor stars and no other features. A modern-epoch spectral energy distribution shows bright emission from hot dust having Tdust>600 K. Historical infrared data reveal generally cooler dust color temperatures combined with long-term fading trends, but provide no discernible correlation between flux level and temperature. Investigating the most mid-infrared variable R Cor Bor stars found in IRAS, AKARI, and WISE data reveals similar fading trends, bursts that can show a factor of up to 10 change in flux density between epochs, and blackbody-fit dust color temperatures that span 400-1300 K. While some R Cor Bor stars such as IRAS 00450+7401 appear to undergo fade/burst cycles in the mid-infrared, significant gaps in temporal coverage prevent conclusively identifying any preferred timescale for their mid-infrared variability and circumstellar dust temperature changes.

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William A. Burris, Carl Melis, Allen W. Shafter, Georgia V. Panopoulou, Edward L. Wright, John Della Costa. 2023-06-20. IRAS 00450+7401 and the mid-infrared fade/burst cycle of R Coronae Borealis-type stars. https://doi.org/10.3847/1538-3881%2Facda93

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