The evolution of ice mantles during the star formation process: an IceAge JWST studyof Chamaeleon I
J. A. Noble,1 for the IceAge team2
1Physics of the Interactions of Ions and Molecules (PIIM) laboratory, CNRS/Aix-MarseilleUniversité, France
2
PI M. K. McClure and co-PI H. Linnartz, Leiden Observatory, Leiden; co-PI A. C. A. Boogert,
Institute for Astronomy/InfraRed Telescope Facility, Honolulu
Icy grain mantles are the main reservoir for volatile elements in star-forming regions. The IceAge
Early Release Science program [1,2] on the James Webb Space Telescope proposes to observe
infrared spectra of objects at various stages of star formation, from dense cloud to protoplanetary
disk. By observing Chamaeleon I – a representative low-mass star-forming region containing
objects at each of these stages – we aim to trace the evolution of pristine and complex ice
chemistry that accompanies the physical evolution of the objects. The dense cloud was observed
using the NIRCam, NIRSpec and MIRI instruments in summer 2022, providing high spectral
resolution (R~1500-3000) and sensitivity (S/N>100) infrared spectra from 2.5 to 13 μm of two
highly extincted background stars (Av < 100) and additional L and M band spectra towards
hundreds more field stars. In this talk, we will present the first results of the IceAge program: acomplete ice inventory towards observed lines of sight, including derived column densities for
expected ice species as well as the first detection of several species along lines of sight in aquiescent cold core [3]. We will also present some more recent advances and give perspectives forthe rest of the IceAge program, with a particular focus on the NIRCam observations that permit
mapping the spatial distribution of ices down to ~20-50 au with the aim of identifying the onset ofice formation.

Figure 1: Star-forming region Chamaeleon I, imaged by the JWST NIRCam instrument.[4]References[1]
http://jwst-iceage.org/[2]
M. McClure, J. Bailey, T. Beck, A. C. A. Boogert, W. Brown, P. Caselli., J. Chiar, E. Egami, H. J. Fraser, R.
Garrod, K. D. Gordon, S. Ioppolo, I. Jimenez-Serra, J. Jorgensen, L. E. Kristensen, H. Linnartz, M. McCoustra, N.
Murillo, J. A. Noble, K. Oberg, M. E. Palumbo, Y. J. Pendleton, K. M. Pontoppidan, E. F. van Dishoeck. & S. Viti
“IceAge: Chemical Evolution of Ices during Star Formation” 2017, JWST cycle 0 ERS Accepted Proposal 1309,
arxiv: 2017jwst.prop.1309M[3]
M. K. McClure, W. R. M. Rocha, K. M. Pontoppidan, N. Crouzet, L. E. U. Chu, E. Dartois, T. Lamberts, J. A.
Noble, Y. J. Pendleton, G. Perotti, D. Qasim, M. G. Rachid, Z. L. Smith, F. Sun, T. L. Beck, A. C. A. Boogert, W. A.
Brown, P. Caselli, S. B. Charnley, H. M. Cuppen, H. Dickinson, M. N. Drozdovskaya, E. Egami, J. Erkal, H. Fraser, R.
T. Garrod, D. Harsono, S. Ioppolo, I. Jiménez-Serra, M. Jin, J. K. Jørgensen, L. E. Kristensen, D. C. Lis, M. R. S.
McCoustra, B. A. McGuire, G. J. Melnick, K. I. Öberg, M. E. Palumbo, T. Shimonishi, J. A. Sturm, E. F. vanDishoeck & H. Linnartz “An IceAge JWST inventory of dense molecular cloud ices” 2023, Nature Astronomy, doi:
10.1038/s41550-022-01875-w[4]
Press release 23/01/23 23 https://esawebb.org/news/weic2303/ Image Credit: NASA, ESA, CSA, and M.
Zamani (ESA/Webb); Science: M. K. McClure (Leiden Observatory), F. Sun (Steward Observatory), Z. Smith (OpenUniversity), and the Ice Age ERS Team.

https://esawebb.org/news/weic2303/