J/A+A/702/A193 Jupiter Trojans Gaia DR3 spectrophotometry (Fornasier+, 2025)
Spectrophotometry of Jupiter Trojan with the Gaia DR3 catalog.
Fornasier S., El-Bez-Sebastien N.
<Astron. Astrophys. 702, A193 (2025)>
=2025A&A...702A.193F 2025A&A...702A.193F (SIMBAD/NED BibCode)
ADC_Keywords: Solar system ; Minor planets ; Optical ; Spectrophotometry
Keywords: methods: data analysis - techniques: photometric - catalogs -
minor planets, asteroids: general
Abstract:
Jupiter Trojans are considered to be among the most pristine bodies in
the Solar System. They are believed to have originated from the Kuiper
belt and subsequently captured by Jupiter during planetary migrations.
We present the spectral characterization of Jupiter Trojans using data
from the third data release by the Gaia mission (DR3) spectral catalog
and from the literature, along with an analysis of the spectral slope
correlations with physical parameters and a comparison with the main
properties of outer Solar System bodies.
The Gaia DR3 minor bodies spectral catalog comprises 478 Jupiter
Trojans. Gaia spectrophotometry is available in 16 spectrophotometric
points covering the 0.33-1.08um range. In this sample, we retained
Trojans with a signal-to-noise ratio of S/N>20 and we visually
inspected the quality of those with lower S/N values. This process
reduces the Trojans Gaia database to 320 objects. To enhance the
statistical analysis, we also included the visible spectra (in the
∼0.45-0.95um range) of Trojans available in the literature. The
final dataset includes 519 Trojans, comprising 291 in the leading
swarm (L4) and 228 in the trailing swarm (L5), which we classified
using the Bus-Demeo and Mahlke classification schemes.
The Trojan population is dominated by featureless asteroids with red
spectral slopes belonging to the D-type, with an important fraction
(∼40%) belonging to the Z-class (in Mahlke taxonomy), characterized by
very red slopes. The L4 swarm shows a higher spectral variability and
a higher amount, by a factor of 2, of less spectrally red asteroids
belonging to the C, P, and X classes that are mainly associated with
family members. Once excluding peculiar objects such as the members of
Eurybates family, known to be dominated by C-type asteroids, the two
swarms have indistinguishable average slopes and very similar albedo
values (7.86±0.15% and 7.35±0.15% for the L4 and L5 swarms,
respectively). We did not observe any spectral color bi-modality
distribution, conversely to the results reported in the literature,
which had previously led to the suggestion that Trojans originated
from two different regions of the protoplanetary disk: one before and
one behind the stability lines of some volatile ices, such as H2S. The
spectral slope distribution is peaked at 9-11%/1000Å and it is very
narrow compared to that of Transneptunian objects (TNOs) or cometary
nuclei.
In the visible range, L4 and L5 Jupiter Trojans show very similar
average slope and albedo values, even if the L4 swarm have a higher
spectral variability mostly associated with some peculiar families.
This points toward a common origin of the bodies of the two swarms,
likely from the Transneptunian region. The visible spectral slopes of
Trojans match those of the less red TNOs, notably those classified as
bowl-type by Pinilla-Alonso et al. (2025NatAs...9..230P 2025NatAs...9..230P), and lack of
extremely red and organic rich surfaces observed in the TNOs. We
suggest that the Jupiter Trojans might have been captured by Jupiter
from the Centaurs and scattered disk population. We propose that the
lack of extremely red objects among Trojans could be due to the
removal of the organic-rich crust through the sublimation of volatiles
and collisions as TNOs migrated inward in the Solar System.
Description:
We present the results of the taxonomic classification and spectral
slope analysis of the largest sample of Jupiter Trojans investigated
to date, comprising 519 objects. The sample includes primarily
spectrophotometric data from the Gaia DR3 spectral catalog, as well as
data from the literature. Notably, it includes 268 new
spectrophotometric data on Trojans that have never been observed
before.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tableb1.dat 55 291 L4 Trojans investigated
tableb2.dat 56 228 L5 Trojans investigated
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See also:
I/359 : Gaia DR3 Part 5. Solar System (Gaia Collaboration, 2022)
Byte-by-byte Description of file: tableb?.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- Object Object number
8- 12 F5.1 km D ? Diameter
14- 16 F3.1 km e_D ? Diameter error
18- 22 F5.2 10-5/nm S Spectral slope in the visible range
(in %/1000Å)
24- 27 F4.2 10-5/nm e_S Spectral slope in the visible range error
(in %/1000Å)
29- 33 F5.3 --- pv ? Geometric albedo
35- 39 F5.3 --- e_pv ? Geometric albedo error
41 A1 --- T1 Bus-Demeo taxonomy
43 A1 --- T2 Mahlke taxonomy
45- 49 F5.1 --- SNR ? Signal-to-noise ratio computed for
objects having Gaia's spectra
51- 56 A6 --- Refs References (1)
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Note (1): Referneces for the spectra from the litterature as follows:
1 = Gaia Collaboration Galluccio et al. (2023A&A...674A..35G 2023A&A...674A..35G)
2 = Fornasier et al. (2007Icar..190..622F 2007Icar..190..622F)
3 = Roig et al. (2008A&A...483..911R 2008A&A...483..911R)
4 = Melita et al. (2008Icar..195..686M 2008Icar..195..686M)
5 = Jewitt et al. (1990AJ....100..933J 1990AJ....100..933J)
6 = Lazzaro et al. (2004Icar..172..179L 2004Icar..172..179L)
7 = Fitzsimmons et al. (1994A&A...282..634F 1994A&A...282..634F)
8 = Bendjoya et al. 2004 (2004Icar..168..374B 2004Icar..168..374B)
9 = Xu et al. (1995Icar..115....1X 1995Icar..115....1X)
10 = Bus and Binzel (2002Icar..158..106B 2002Icar..158..106B)
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Acknowledgements:
Sonia Fornasier, Sonia.Fornasier(at)obspm.fr
(End) Patricia Vannier [CDS] 27-Aug-2025