Marco Micheli

JWST Reveals Refractory-Rich Water Ice in Interstellar Comet 3I/ATLAS: Evidence for a Continuum of Grain Properties across Protoplanetary Disks

Silvia Protopapa, Michael S. P. Kelley, Martin Cordiner, Stefanie N. Milam et autres

We present JWST/NIRSpec PRISM observations of the interstellar comet 3I/ATLAS obtained on 2025 August 6 (Epoch 1), 2025 December 22 (Epoch 2), and 2026 April 1 (Epoch 3), spanning eight months around perihelion at heliocentric distances of 3.3, 2.4, and 5.7 au, …

Gemini and Apache Point Multi-band Optical Imaging Characterization of Fragmenting Long-period Comet C/2025 K1 (ATLAS)

Carl Ingebretsen, Bryce Bolin, Meredith A. MacGregor, Carey Lisse et autres

We present results from multi-band g, r, and i, observations of C/2025 K1 (ATLAS) taken with the Gemini North 8.1-m/GMOS imager on 2025 December 6 and December 24, and u, g, r, i, and z observations with the Astrophysical Research Consortium (ARC) …

Best practices for obtaining astrometric observations from JWST (274) NIRCam data

Marco Micheli, B. J. Holler

The James Webb Space Telescope (JWST), with its near-infrared imager NIRCam, is capable of obtaining detections of small bodies down to what would correspond to a visual magnitude of about 31. However, the complexity of NIRCam introduces multiple subtle effects in the …

JWST Spatial-Spectral Mapping of Green Comet C/2022 E3 (ZTF)

Stefanie N. Milam, Nathan X. Roth, Geronimo Luis Villanueva, Dominique Bockelée-Morvan et autres

We report a survey of molecular emission from cometary volatiles using the James Webb Space Telescope (JWST) toward Oort cloud comet C/2022 E3 (ZTF) carried out on UT 2023 February 28 and March 1 at a heliocentric distance (rH) of 1.33 au. …

JWST and Gemini Observations of the Active Centaur 450P/LONEOS: Nucleus and Coma Characterizations

Charles Schambeau, Michael S. P. Kelley, Maria Womack, E. Lilly et autres

Abstract Between 2019 and 2024, we used the Gemini-N and JWST observatories to conduct a detailed case study of the active Centaur 450P/LONEOS, whose orbit was significantly altered by a close Saturn encounter in 1992. Gemini-N Gemini Multi-Object Spectrograph optical images likely …

us, fr, es (code pays fourni par la source)

Preserved primordial material detected in a Centaur coma 9 au from the Sun

E. Lilly, Charles Schambeau, R. Brunetto, Sasha Cryan et autres

us, fr, ca, sk (code pays fourni par la source)

JWST and Gemini Observations of the Active Centaur 450P/LONEOS: Nucleus and Coma Characterizations

Charles Schambeau, Michael S. P. Kelley, Maria Womack, E. Lilly et autres

Between 2019 and 2024, we used the Gemini-N and JWST observatories to conduct a detailed case study of the active Centaur 450P/LONEOS, whose orbit was significantly altered by a close Saturn encounter in 1992. Gemini-N GMOS optical images likely captured the first …

JWST Observations of Asteroid 2024 YR4 Rule Out a 2032 Lunar Impact and Demonstrate a New Regime for Planetary Defense Follow-up

Julien de Wit, Andrew S. Rivkin, Marco Micheli, Davide Farnocchia et autres

At the end of its discovery apparition, the $\sim$60 m near-Earth object 2024 YR4 was associated with a non-zero probability of lunar impact during its 2032 December 22 close approach. While posing no threat to Earth, a lunar impact of this scale …

Emerging Diversity Among the Main-Belt Comets: Insights from JWST and Ground-Based Observations of 457P/Lemmon-PANSTARRS

John W. Noonan, Henry H. Hsieh, Michael S. P. Kelley, Dennis Bodewits et autres

We present JWST NIRSpec and NIRCam observations of 457P/Lemmon-PANSTARRS, a main-belt comet that displayed activity around its 2020 perihelion and that was observed to regain activity during its 2024 perihelion by a ground-based observing campaign. The previous successful measurements of water production …

Characterization of the Volatile Properties of 133P/Elst-Pizarro and Other Main-Belt Comets with JWST and Ground-Based Observations

Henry H. Hsieh, John W. Noonan, Michael S. P. Kelley, Dennis Bodewits et autres

We report results from an analysis of the volatile composition and evolution of main-belt comet (MBC) 133P/Elst-Pizarro using JWST NIRSpec and NIRCam observations and ground-based observations during its 2024 active apparition, and also assess the body of JWST MBC observations acquired to …

Coma Physics of an Interstellar Object: JWST Spatial-Spectral Mapping of 3I/ATLAS

Nathan X. Roth, Martin Cordiner, Stefanie N. Milam, Geronimo Luis Villanueva et autres

We report a survey of molecular emission from cometary volatiles using the James Webb Space Telescope (JWST) toward interstellar object 3I/ATLAS carried out on UT 2025 December 22 and 23 at a heliocentric distance ($r_H$) of $2.37-2.41$ au. These measurements of CO, …

An Enriched Methane D/H Ratio in the Interstellar Object 3I/ATLAS

Nathan X. Roth, Martin Cordiner, Stefanie N. Milam, Geronimo Luis Villanueva et autres

Interstellar objects are interlopers from other planetary systems, and their volatile compositions provide a glimpse into planet formation around their host star. We present near-infrared spectra of the coma of interstellar object 3I/ATLAS measured with the James Webb Space Telescope. Our results …