An Ongoing Mid-infrared Outburst in the White Dwarf 0145+234: Catching in Action the Tidal Disruption of an Exoasteroid?

Wang, Ting-gui and Jiang, Ning and Ge, Jian and Cutri, Roc M. and Jiang, Peng and Sheng, Zhengfeng and Zhou, Hongyan and Bauer, James and Mainzer, Amy and Wright, Edward L. (2019) An Ongoing Mid-infrared Outburst in the White Dwarf 0145+234: Catching in Action the Tidal Disruption of an Exoasteroid? The Astrophysical Journal, 886 (1). L5. ISSN 2041-8213

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Abstract

We report the detection of a large-amplitude MIR outburst in the white dwarf (WD) 0145+234 in the NEOWISE Survey data. The source had a stable MIR flux before 2018, and was brightened by about 1.0 magnitude in the W1 and W2 bands within half a year and has been continuously brightening since then. No significant variations are found in the optical photometry data during the same period. This suggests that this MIR outburst is caused by recent replenishing or redistribution of dust, rather than intrinsic variations of the WD. Spectral energy distribution modeling of 0145+234 suggests that there was already a dust disk around the WD in the quiescent state, and both of the temperature and surface area of the disk evolved rapidly since the outburst. The dust temperature was ≃1770 K in the initial rising phase, close to the sublimation temperature of silicate grains, and gradually cooled down to around 1150 K, while the surface area increased by a factor of about six during the same period. The inferred closest distance of dust to the WD is within the tidal disruption radius of a gravitationally bounded asteroid. We estimated the dust mass to be between 3 × 1015 and 3 × 1017ρ/(1 g cm−3) kg for silicate grains of a power-law size distribution with a high cutoff size from 0.1 to 1000 μm. We interpret this as a possible tidal breakup of an exoasteroid by the WD. Further follow-up observations of this rare event may provide insights on the origin of dust disk and metal pollution in some WDs.

Item Type: Article
Subjects: Research Scholar Guardian > Physics and Astronomy
Depositing User: Unnamed user with email support@scholarguardian.com
Date Deposited: 29 May 2023 06:41
Last Modified: 29 Jan 2024 05:53
URI: http://science.sdpublishers.org/id/eprint/976

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