Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 2508.19872

Jupiter Trojans spectrophotometry using Gaia DR3 catalog

Sonia Fornasier·Noemie El-Bez-Sebastien
View original source ↗Read source document ↗Export metadata ↓

Abstract

We present the spectral characterization of Jupiter Trojans using data from the Gaia mission DR3 spectral catalog (320 spectra of good quality) and from the literature. Gaia spectrophotometry is available in 16 spectrophotometric points covering the 0.33-1.08 $μ$m range. The final dataset includes 519 Trojans, 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, and an important fraction ($\sim$ 40\%) belong 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, mainly associated with families members. Once excluding peculiar families members the two swarms have very similar average slope and albedo values (7.86 $\pm$ 0.15\% and 7.35 $\pm$0.15\% for the L4 and L5 swarms, respectively). This points toward a common origin of the bodies of the two swarms, likely from the Transneptunian region. We do not observe a spectral color bi-modality distribution, conversely to the results previously reported in the literature. The spectral slope distribution, peaked at 9-11 \%/1000 Å, it is very narrow compared to that of Transneptunian objects (TNOs) or cometary nuclei. Trojans visible spectral slopes match those of the less red TNOs, and lack of extremely red and organic rich bodies. We suggest that the Jupiter Trojans might have been captured by Jupiter from the Centaurs and scattered disk population, and that the lack of extremely red objects among Trojans is due to removal of the organic-rich crust through the sublimation of volatiles and collisions as TNOs migrated inward in the Solar System.

Explore related subjects

astro-ph.EP

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Sonia Fornasier, Noemie El-Bez-Sebastien. 2025-08-27. Jupiter Trojans spectrophotometry using Gaia DR3 catalog. https://doi.org/10.1051/0004-6361%2F202555999

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Detectability of resolved hydrogen lines from the accretion shock at gas giants and their CPDs

Fewer gas giants have been caught in their accretion phase than mature ones are known. Extremely Large Telescope (ELT) instruments will have a higher sensitivity and a smaller inner working angle than tools up to now, which should increase search yields. We examine what METIS, the first-generation ELT spectrograph with R=1e5, can reveal about accreting gas giants. We focus on the accessible hydrogen recombination lines, mainly Brackett alpha and Pfund-series lines. Our approach is general but we take PDS70b as a fiducial case. It is similar to WISPIT2b. To calculate high-resolution line profiles, we combine a semianalytical multi-D description of the flow onto an accreting planet and its circumplanetary disc (CPD) with local non-LTE shock-emission models. We assume the limiting scenario of no extinction, appropriate for gas giants in gaps, and negligible contribution from magnetospheric accretion. We use simulated detector sensitivities to compute needed observing times. Both the planet- and the CPD-surface shocks contribute to the line, which has a Gaussian core but wider, asymmetrical wings. The line is much narrower than the free-fall velocity, and in fact has a nearly constant FWHM=30--40 km/s at low densities. For our fiducial accretion rate onto PDS70b, the Br-a line peak excess is as strong as the photospheric continuum, modulated mostly by H2O features. At Br-a, already the continuum of PDS 70 b yields a per-bin S/N=12 in 4h. With ProDiMo, we estimate the CPD not to hinder the detection of the line emission. The peak excess should require only 10 min to reach S/N=3. For pure shock emission, the line shape is barely sensitive to the planetary or system parameters. A complex profile would indicate that magnetospheric accretion contributes significantly. The high spectral resolution of METIS will help reveal line shapes even of faint accretors with great fidelity.

astro-ph.EP↗
arXiv2026

Centaur Longevity Revisited: Lifetime Dispersion and the Bailey & Malhotra Classifications under Modern Orbital Solutions

Centaurs occupy dynamically unstable orbits between Jupiter and Neptune and are typically removed by giant-planet encounters within a few Myr. Bailey and Malhotra (hereafter BM09) classified the known Centaurs, from 2007 orbits, into a short-lived diffusing class (D), a resonance-hopping class (R), and a long-lived, quasi-stable class (Q); their sole Q object, 2005 TH173, was fit to a 17\,d arc. We revisit both halves of that analysis on modern Jet Propulsion Laboratory Small-Body Database (SBDB) orbits (retrieved 2026-07-26), integrating clone ensembles of each object with the REBOUND WHFast $N$-body integrator. We ask (i) whether tighter orbital precision narrows the dispersion in clone lifetimes, and (ii) whether the BM09 labels survive on updated elements. Among 65 genuine Centaurs with arc $\ge 30$\,d and no censored clones, $σ(\log_{10}\mathrm{lifetime})=0.54$\,dex (a factor of 3.5). Conditioned on present-day $a$, $e$, $i$, and $q$, this dispersion is insensitive to relative semimajor-axis uncertainty (slope $=-0.002$\,dex per decade in $σ_a/a$; 95\% confidence interval $-0.034$ to $+0.030$) --- a chaos floor. On the D/Q axis, 49/50 comparable objects retain their BM09 class; 2005 TH173 is the exception (Q$\to$D): 80/100 clones escape before 10\,Myr (median 2.99\,Myr), and a 40\,Myr integration of the same initial conditions returns 88\,D / 12\,R / 0\,Q. None of the 30 multi-opposition 2007 orbits changes class; two short-arc objects leave the Centaur zone.}

astro-ph.EP↗
arXiv2026

Feasibility of the Phobos 1 Hypothesis for Dark Comet 1998 KY$_{26}$

The asteroid 1998 KY$_{26}$ has been the subject of thorough observation, both optical and radar, from shortly following its discovery on 28 May 1998, through 2 further close apparitions in 2020 and 2024. This has previously allowed an accurate characterization of the object, including an unusually rapid spin-rate with period 5.3516 $\pm$ 0.0001 minutes, a diameter of 11 $\pm$ 2 m, and a high albedo of $\sim{0.52}$. Furthermore, the presence of significant nongravitational accelerations (NGAs), with no detectable shedding of gas or dust, has stimulated the 'dark comet' categorization, with JAXA repurposing their Hayabusa2$\sharp$ spacecraft to rendezvous with the object in 2031. We follow-up the astrodynamical evidence pointing to the possibility this may actually be the lost Soviet Phobos 1 probe, and analyse various photometry and astrometry associated with 1998 KY$_{26}$ to further investigate the feasibility of this hypothesis. We find a first order approximation of the Phobos 1 spacecraft provides compelling agreement to 8 light curves of the object and further that modelling NGAs as solar radiation pressure (SRP) on a cylinder or solar panels provide significant reductions in residual of $\sim{11} \%$ with respect to the 260 astrometric and radar measurements. Although an investigation of this kind cannot be conclusive, nevertheless the results here add strong weight to the Phobos 1 hypothesis, and we find no clear contradictory evidence. The spin pole in Ecliptic J2000 coordinates, calculated from photometry based on the Phobos 1 assumption is $(λ,β)=({151^{+1}_{-2}}^{\circ},{+11^{+12}_{- 3}}^{\circ})$ , where the quoted ranges represent approximate 68.3\% confidence levels.

astro-ph.EP↗