Skip to content
DraconiticResearch
Search Sources API
203,203 studies31 sourcesUpdated 42 min ago
Peer-reviewedCC BYThe Astronomical Journal

Contemporaneous Optical and Near-infrared Observations of the Interstellar Comet 3I/ATLAS Pre- and Postperihelion

  • K. Medler1
  • W. B. Hoogendam1
  • Chris Ashall1
  • Bin Yang2
  • James J. Wray3,1
  • Benjamin J. Shappee1
  • Karen J. Meech1
  • Michael A. Tucker4
  • Katie Auchettl5,6
  • D. Desai1
  • Jason T. Hinkle7,1,8
  • Andrew Hoffman1
3 more authors
  • M. E. Huber1
  • D. O. Jones1
  • Ruining Zhao9
9 affiliations
  1. 1University of Hawai‘i
  2. 2Universidad Diego Portales
  3. 3Georgia Institute of Technology
  4. 4The Ohio State University
  5. 5The University of Melbourne
  6. 6University of California
  7. 7NSF-Simons AI Institute for the Sky (SkAI)
  8. 8University of Illinois Urbana-Champaign
  9. 9Chinese Academy of Sciences
Open at sourceDOICite

Abstract

Interstellar objects provide a unique view into the formation of other star systems. Here we present spectroscopic observations of the recently discovered interstellar object 3I/ATLAS between a heliocentric distance of 3.7–1.8 au on either side of its travels through perihelion. We obtained several observations with the Keck-I/LRIS, Keck-II/NIRES, Gemini/GMOS, and UH88/SNIFS spectrographs, covering a wavelength range of 0.3–2.5 μ m. We report the continued emission of both Ni and CN, along with postperihelion detections of Fe and a weak detection of C 3 . We determine the spectral slope across optical and near-infrared (NIR) wavelengths and find a positive spectral slope in the optical, with values ranging from ∼21% to 27% in the blue regions (0.4–0.55 μ m) to ∼6%–10% in the red (0.65–0.9 μ m) regions. In contrast, the NIR showed a negative spectral slope of ∼−0.9% between 0.9 and 1.5 μ m and ∼−2.3% between 1.9 and 2.5 μ m. 3I/ATLAS shows a clear turnover in its spectral shape at ∼1.1 μ m, consistent with scattered sunlight from the dusty coma. Finally, in the NIR spectra presented in this work, we do not detect any of the water ice features that were identified in an earlier NIR observation of 3I/ATLAS. Our observations of 3I/ATLAS in the NIR show a similar shape to the NIR spectrum of 2I/Borisov as it approached perihelion.

Related

  1. Postperihelion Coma Composition of the Interstellar Comet 3I/ATLAS from Optical Spectroscopy
    Ruining Zhao, Xiliang Zhang, Bin Yang +4
    The Astrophysical Journal LettersPeer-reviewedCC BYFull text11 citedPlanetary science & exoplanetsOpenAlex
  2. Postperihelion Integral Field Spectroscopy of the Interstellar Comet 3I/ATLAS
    W. B. Hoogendam, D. O. Jones, Bin Yang +10
    The Astrophysical JournalPeer-reviewedCC BY14 citedPlanetary science & exoplanetsOpenAlex
  3. GIARPS simultaneous optical and infrared high-spectral-resolution observations of Cepheids I. Limb darkening from cross-correlated radial velocities
    N. Nardetto, R. S. Rathour, M. C. Bailleul +17
    arXivPreprintCC BY 4.0Full textSolar & stellar physicsGeneral physicsarXivHAL
  4. High-resolution optical spectroscopy reveals the distinctive volatile composition of the interstellar comet 3I/ATLAS
    K. Aravind, E. Jehin, C. Opitom +9
    Astronomy & AstrophysicsPeer-reviewedPublisher termsPlanetary science & exoplanetsCrossref
  5. JWST/MIRI Observations of Amorphous Silicates in Interstellar Comet 3I/ATLAS
    Cristina A. Thomas, Michael S. P. Kelley, David E. Harker +11
    arXivPreprintCC BY 4.0Full textGalaxiesPlanetary science & exoplanetsarXiv

Cite

BibTeXRIS
BibTeX
@article{medler2026contemporaneous,
  title = {{Contemporaneous Optical and Near-infrared Observations of the Interstellar Comet 3I/ATLAS Pre- and Postperihelion}},
  author = {K. Medler and W. B. Hoogendam and Chris Ashall and Bin Yang and James J. Wray and Benjamin J. Shappee and Karen J. Meech and Michael A. Tucker and Katie Auchettl and D. Desai and Jason T. Hinkle and Andrew Hoffman and M. E. Huber and D. O. Jones and Ruining Zhao},
  journal = {The Astronomical Journal},
  year = {2026},
  month = jun,
  doi = {10.3847/1538-3881/ae6b71},
  url = {https://doi.org/10.3847/1538-3881/ae6b71},
  note = {CC BY},
}
RIS
TY  - JOUR
TI  - Contemporaneous Optical and Near-infrared Observations of the Interstellar Comet 3I/ATLAS Pre- and Postperihelion
AU  - K. Medler
AU  - W. B. Hoogendam
AU  - Chris Ashall
AU  - Bin Yang
AU  - James J. Wray
AU  - Benjamin J. Shappee
AU  - Karen J. Meech
AU  - Michael A. Tucker
AU  - Katie Auchettl
AU  - D. Desai
AU  - Jason T. Hinkle
AU  - Andrew Hoffman
AU  - M. E. Huber
AU  - D. O. Jones
AU  - Ruining Zhao
PY  - 2026
DA  - 2026/06/12
JO  - The Astronomical Journal
DO  - 10.3847/1538-3881/ae6b71
UR  - https://doi.org/10.3847/1538-3881/ae6b71
AB  - Interstellar objects provide a unique view into the formation of other star systems. Here we present spectroscopic observations of the recently discovered interstellar object 3I/ATLAS between a heliocentric distance of 3.7–1.8 au on either side of its travels through perihelion. We obtained several observations with the Keck-I/LRIS, Keck-II/NIRES, Gemini/GMOS, and UH88/SNIFS spectrographs, covering a wavelength range of 0.3–2.5 μ m. We report the continued emission of both Ni and CN, along with postperihelion detections of Fe and a weak detection of C 3 . We determine the spectral slope across optical and near-infrared (NIR) wavelengths and find a positive spectral slope in the optical, with values ranging from ∼21% to 27% in the blue regions (0.4–0.55 μ m) to ∼6%–10% in the red (0.65–0.9 μ m) regions. In contrast, the NIR showed a negative spectral slope of ∼−0.9% between 0.9 and 1.5 μ m and ∼−2.3% between 1.9 and 2.5 μ m. 3I/ATLAS shows a clear turnover in its spectral shape at ∼1.1 μ m, consistent with scattered sunlight from the dusty coma. Finally, in the NIR spectra presented in this work, we do not detect any of the water ice features that were identified in an earlier NIR observation of 3I/ATLAS. Our observations of 3I/ATLAS in the NIR show a similar shape to the NIR spectrum of 2I/Borisov as it approached perihelion.
SN  - 0004-6256
SN  - 1538-3881
ER  -