From Colors to Spectra and Back Again: First Near-IR Spectroscopic Survey of Neptunian Trojans

In this work, we present 0.7–5.0 μ m spectra of eight Neptunian Trojans (NTs) as observed by the JWST’s NIRSpec instrument. The reddest NT, 2013 VX _30 , exhibits a unique spectrum with strong absorption features between 3 and 4 μ m, while the bluest NT, 2006 RJ _103 , shows negligible water absorpt...

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Main Authors: Larissa Markwardt, Hsing Wen Lin, Bryan J. Holler, David W. Gerdes, Fred C. Adams, Renu Malhotra, Kevin J. Napier
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Planetary Science Journal
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Online Access:https://doi.org/10.3847/PSJ/addecd
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author Larissa Markwardt
Hsing Wen Lin
Bryan J. Holler
David W. Gerdes
Fred C. Adams
Renu Malhotra
Kevin J. Napier
author_facet Larissa Markwardt
Hsing Wen Lin
Bryan J. Holler
David W. Gerdes
Fred C. Adams
Renu Malhotra
Kevin J. Napier
author_sort Larissa Markwardt
collection DOAJ
description In this work, we present 0.7–5.0 μ m spectra of eight Neptunian Trojans (NTs) as observed by the JWST’s NIRSpec instrument. The reddest NT, 2013 VX _30 , exhibits a unique spectrum with strong absorption features between 3 and 4 μ m, while the bluest NT, 2006 RJ _103 , shows negligible water absorption. A principal component analysis comparing these spectra with those of trans-Neptunian objects (TNOs) and Centaurs reveals that most NTs belong to the “bowl-type” spectral group, while 2013 VX _30 is categorized as “cliff-type” in the N. Pinilla-Alonso et al. taxonomy. For the bluest NT in our sample, 2006 RJ _103 shows some evidence that it may be related to carbonaceous asteroids. For the red object 2011 SO _277 , we find no close TNO spectral counterpart. Except for the true outlier 2011 SO _277 , NTs have better spectral analogs among Plutinos and distant Centaurs, suggesting that spectral variation within major groups may arise from current temperature and location, rather than solely from formation regions. Finally, we highlight optical slope (S′) and near-IR slope (SIR _1 ) as effective indicators for distinguishing spectral groups and identifying outliers. These findings enable the use of broadband photometry to explore NT and TNO surface compositions, especially for faint objects, which will be directly applicable to large photometric surveys like the Dark Energy Survey and the Vera C. Rubin Observatory’s LSST.
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spelling doaj-art-bbc6b459f7f344308cac44e2c1f10bcb2025-08-20T03:31:41ZengIOP PublishingThe Planetary Science Journal2632-33382025-01-016715410.3847/PSJ/addecdFrom Colors to Spectra and Back Again: First Near-IR Spectroscopic Survey of Neptunian TrojansLarissa Markwardt0https://orcid.org/0000-0002-2486-1118Hsing Wen Lin1https://orcid.org/0000-0001-7737-6784Bryan J. Holler2https://orcid.org/0000-0002-6117-0164David W. Gerdes3https://orcid.org/0000-0001-6942-2736Fred C. Adams4https://orcid.org/0000-0002-8167-1767Renu Malhotra5https://orcid.org/0000-0002-1226-3305Kevin J. Napier6https://orcid.org/0000-0003-4827-5049Department of Physics, University of Auckland , Science Centre 303, 38 Princes Street Auckland Central, Auckland, 1010, New Zealand ; larissa.markwardt@auckland.ac.nzDepartment of Physics, University of Michigan , 450 Church Street, Ann Arbor, MI 48109-1107, USA; Michigan Institute for Data and AI in Society, University of Michigan , 500 Church Street, Ann Arbor, MI 48109, USASpace Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USADepartment of Physics, University of Michigan , 450 Church Street, Ann Arbor, MI 48109-1107, USA; Department of Astronomy, University of Michigan , 1085 South University Avenue, Ann Arbor, MI 48109-1107, USA; Department of Physics, Case Western Reserve University , 10900 Euclid Avenue, Cleveland, OH 44106, USADepartment of Physics, University of Michigan , 450 Church Street, Ann Arbor, MI 48109-1107, USA; Department of Astronomy, University of Michigan , 1085 South University Avenue, Ann Arbor, MI 48109-1107, USALunar and Planetary Laboratory , 1629 East University Boulevard, Tucson, AZ 85721, USADepartment of Physics, University of Michigan , 450 Church Street, Ann Arbor, MI 48109-1107, USA; Michigan Institute for Data and AI in Society, University of Michigan , 500 Church Street, Ann Arbor, MI 48109, USA; Center for Astrophysics | Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USAIn this work, we present 0.7–5.0 μ m spectra of eight Neptunian Trojans (NTs) as observed by the JWST’s NIRSpec instrument. The reddest NT, 2013 VX _30 , exhibits a unique spectrum with strong absorption features between 3 and 4 μ m, while the bluest NT, 2006 RJ _103 , shows negligible water absorption. A principal component analysis comparing these spectra with those of trans-Neptunian objects (TNOs) and Centaurs reveals that most NTs belong to the “bowl-type” spectral group, while 2013 VX _30 is categorized as “cliff-type” in the N. Pinilla-Alonso et al. taxonomy. For the bluest NT in our sample, 2006 RJ _103 shows some evidence that it may be related to carbonaceous asteroids. For the red object 2011 SO _277 , we find no close TNO spectral counterpart. Except for the true outlier 2011 SO _277 , NTs have better spectral analogs among Plutinos and distant Centaurs, suggesting that spectral variation within major groups may arise from current temperature and location, rather than solely from formation regions. Finally, we highlight optical slope (S′) and near-IR slope (SIR _1 ) as effective indicators for distinguishing spectral groups and identifying outliers. These findings enable the use of broadband photometry to explore NT and TNO surface compositions, especially for faint objects, which will be directly applicable to large photometric surveys like the Dark Energy Survey and the Vera C. Rubin Observatory’s LSST.https://doi.org/10.3847/PSJ/addecdNeptune trojansInfrared spectroscopyMulti-color photometry
spellingShingle Larissa Markwardt
Hsing Wen Lin
Bryan J. Holler
David W. Gerdes
Fred C. Adams
Renu Malhotra
Kevin J. Napier
From Colors to Spectra and Back Again: First Near-IR Spectroscopic Survey of Neptunian Trojans
The Planetary Science Journal
Neptune trojans
Infrared spectroscopy
Multi-color photometry
title From Colors to Spectra and Back Again: First Near-IR Spectroscopic Survey of Neptunian Trojans
title_full From Colors to Spectra and Back Again: First Near-IR Spectroscopic Survey of Neptunian Trojans
title_fullStr From Colors to Spectra and Back Again: First Near-IR Spectroscopic Survey of Neptunian Trojans
title_full_unstemmed From Colors to Spectra and Back Again: First Near-IR Spectroscopic Survey of Neptunian Trojans
title_short From Colors to Spectra and Back Again: First Near-IR Spectroscopic Survey of Neptunian Trojans
title_sort from colors to spectra and back again first near ir spectroscopic survey of neptunian trojans
topic Neptune trojans
Infrared spectroscopy
Multi-color photometry
url https://doi.org/10.3847/PSJ/addecd
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