SPHEREx Discovery of Strong Water Ice Absorption and an Extended Carbon Dioxide Coma in 3I/ATLAS

作者：C. M. Lisse, Yoonsoo P. Bach, Sean Bryan, B. P. Crill, A. Cukierman, Olivier Doré, Beth Fabinsky, Andreas L. Faisst, Phillip Korngut, Gary J. Melnick, Zafar Rustamkulov, Volker Tolls, M. W. Werner, Michael L. Sitko, Chansey Champagne, Michael S. Connelley, Joshua P. Emery, Y. R. Fernández, Bo Yang, the SPHEREx Science Team · 发表于：Research Notes of the AAS · 年份：2025 · DOI：10.3847/2515-5172/ae0293 · 被引用次数：23 · 研究领域：Atmospheric Ozone and Climate、Astro and Planetary Science、Ionosphere and magnetosphere dynamics

Abstract In mid-August 2025, 0.75–5.0 μ m SPHEREx imaging spectrophotometric and ancillary NASA-IRTF/SpeX 0.7–2.5 μ m low-resolution spectral observations of 3I/ATLAS were obtained. The combined spectrophotometry is dominated by features due to water ice absorption and CO 2 gas emission. A bright, ∼3′ radius CO 2 gas coma was clearly resolved, corresponding to Q gas,CO2 ∼9.4 × 10 26 molecules s −1 . From the SPHEREx photometry, we put conservative, preliminary 3 σ upper limits on the gas production rates for H 2 O and CO of 1.5 × 10 26 and 2.8 × 10 26 molecules s −1 , respectively. No obvious jet, tail, or trail structures were found in SPHEREx images. If we assume all observed 1 μ m flux is scattered light from a p v = 0.04 albedo spherical nucleus, then the radius would be R nuc ∼ 23 km. Given the nucleus size limit R nuc < 2.8 km from D. Jewitt et al., we conclude >99% of the measured SPHEREx continuum flux is from coma dust.