2025RNAAS...9..242L

Query : 2025RNAAS...9..242L

2025RNAAS...9..242L - Research Notes of the AAS, 9, 242 (2025/September-0)

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

LISSE C.M., BACH Y.P., BRYAN S., CRILL B.P., CUKIERMAN A., DORE O., FABINSKY B., FAISST A., KORNGUT P.M., MELNICK G., RUSTAMKULOV Z., TOLLS V., WERNER M., SITKO M.L., CHAMPAGNE C., CONNELLEY M., EMERY J.P., FERNANDEZ Y.R., YANG B. (The SPHEREx Science Team)

Abstract (from CDS):

In mid-August 2025, 0.75-5.0 μm SPHEREx imaging spectrophotometric and ancillary NASA-IRTF/SpeX 0.7-2.5 μm low-resolution spectral observations of 3I/ATLAS were obtained. The combined spectrophotometry is dominated by features due to water ice absorption and CO2 gas emission. A bright, ∼3' radius CO2 gas coma was clearly resolved, corresponding to Qgas,CO2∼9.4 × 1026 molecules s–1. From the SPHEREx photometry, we put conservative, preliminary 3σ upper limits on the gas production rates for H2O and CO of 1.5 × 1026 and 2.8 × 1026 molecules s–1, respectively. No obvious jet, tail, or trail structures were found in SPHEREx images. If we assume all observed 1 μm flux is scattered light from a pv = 0.04 albedo spherical nucleus, then the radius would be Rnuc ∼ 23 km. Given the nucleus size limit Rnuc < 2.8 km from D. Jewitt et al., we conclude >99% of the measured SPHEREx continuum flux is from coma dust.

Abstract Copyright: © 2025. The Author(s). Published by the American Astronomical Society.

Journal keyword(s): Interstellar objects - Small Solar System bodies - Exocomets - Near infrared astronomy - Infrared photometry - Infrared spectroscopy - Carbon dioxide - Coma dust - Comet volatiles - Ice spectroscopy

Simbad objects: 2

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Number of rows : 2
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 HD 148744 PM* 16 30 41.3706820752 -13 06 58.799541420   9.87 9.24     G2V 21 0
2 TYC 447-508-1 * 18 42 45.0084677256 +00 08 04.693469856 13.092 13.057 12.425 12.064 11.716 ~ 44 0

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