J/A+A/707/A131 Lightcurve inversion modeling with GaiaDR3 (MacLennan+, 2026)
Asteroid characterization using Data Release 3.
I. Shapes, spins, and scattering properties.
MacLennan E.M., Pentikaeinen H., Uvarova E., Muinonen K., Penttilae A.,
Wilawer E., Oszkiewicz D.A., Cellino A., Tanga P., Wang X., Virkki A.
<Astron. Astrophys. 707, A131 (2026)>
=2026A&A...707A.131M 2026A&A...707A.131M (SIMBAD/NED BibCode)
ADC_Keywords: Solar system ; Minor planets ; Photometry ; Optical
Keywords: methods: numerical - methods: statistical - catalogs -
minor planets, asteroids: general
Abstract:
The third Gaia data release (DR3) contains high-precision,
sparse-in-time brightness measurements of over 150000 asteroids. We
employed a light-scattering inversion technique to estimate the
rotation periods, spin pole orientations, shapes, and photometric
phase function parameters (slope and absolute magnitude) of over 8000
asteroids based solely on DR3 photometry. Using triaxial ellipsoid and
convex shapes, we sought the best-fit shape, spin, and linear slope,
along with their uncertainties, via a Markov chain Monte Carlo
sampling technique. We also fit HG12 and HG1G2 phase functions from
predicted brightnesses derived from the fit shapes. Using previously
reported diameters, the Gaia G-band geometric albedos were calculated.
Variations in the spin and shape properties were assessed among
various families and background populations of the Main Belt. We found
that for the vast majority of our objects the best-fit ellipsoid spin
poles are comparable to that of a convex shape. We rejected 15% of
convex shapes and used the acceptable solutions to investigate
differences in the shape distribution of families in the Main Belt.
Revisiting the amplitude phase relationship, we found a strong
dependence on the shape b/a elongation. The Bond albedo was calculated
from the phase integral and shown to correlate well with the G12 slope
parameter and known taxonomic classifications. The G-band absolute
magnitudes and geometric albedos are systematically fainter than
V-band values. The assumption of ellipsoid shape for sparse datasets
is sufficient for estimating the spin pole longitude and latitude. We
find no correlation between the shapes and spins of main-belt asteroid
families and their ages. Absolute magnitudes and phase functions
derived from Gaia photometry should be favored over the V band when
estimating the solar energy budget, such as in thermal modeling
applications. Asteroid taxonomies can be assessed to some degree from
the photometric slopes and albedos.
Description:
Inversion results from modeling of Gaia DR3 photometry are presented.
Spin and shape parameters, along with their uncertainties, for
ellipsoid and convex shape assumptions are provided for each object.
The derived photometric slope and absolute magnitudes are also
included and used to derive the albedo (geometric and Bond) from the
previously determined diameter, if available.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tableb1.dat 131 8277 Inversion results from modeling of Gaia DR3
photometry for ellipsoid shape assumption
tableb2.dat 200 8277 Inversion results from modeling of Gaia DR3
photometry for convex shape assumption
--------------------------------------------------------------------------------
See also:
I/359 : Gaia DR3 Part 5: Solar System (Gaia Collaboration, 2022)
J/A+A/707/A132 : Taxonomic classification of asteroids (Pentikainen+, 2026)
Byte-by-byte Description of file: tableb1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- Number Asteroid number
8- 26 F19.12 h Prot Rotation period
28- 46 F19.12 h e_Prot Uncertainty in rotation period
48- 52 F5.1 deg lambda Spin axis ecliptic longitude
54- 58 F5.1 deg e_lambda Uncertainty in spin axis longitude
60- 64 F5.1 deg beta Spin axis ecliptic latitude
66- 69 F4.1 deg e_beta Uncertainty in spin latitude
71- 75 F5.3 --- b/a b to a axis ratio (1)
77- 81 F5.3 --- e_b/a ? Uncertainty in b to a
83- 87 F5.3 --- c/a c to a axis ratio (1)
89- 93 F5.3 --- e_c/a ? Uncertainty in c to a
95- 99 F5.3 mag/rad beta0 Photometric slope
101-105 F5.3 mag/rad e_beta0 Uncertainty in photometric slope
107-112 F6.3 mag HGaia Absolute magnitude
114-118 F5.3 mag e_HGaia Uncertainty in absolute magnitude
120-124 F5.3 mag rms Root mean square of the fit
126-131 F6.1 --- AIC Akaike Information Criterion
--------------------------------------------------------------------------------
Note (1): no error value signify an upper limit for b/a or c/a axis ratios.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tableb2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- Number Asteroid number
8- 27 F20.13 h Prot Rotation period
28- 45 F18.13 h e_Prot Uncertainty in rotation period
47- 51 F5.1 deg lambda Ecliptic spin axis longitude
53- 57 F5.1 deg e_lambda Uncertainty in spin axis longitude
59- 63 F5.1 deg beta Ecliptic spin axis longitude
65- 68 F4.1 deg e_beta Uncertainty in spin axis latitude
70- 74 F5.3 mag/rad beta0 Photometric slope
76- 80 F5.3 mag/rad e_beta0 Uncertainty in photometric slope
82- 87 F6.3 --- G12 HG12 slope parameter
89- 93 F5.3 --- e_G12 ? Uncertainty in G12 (1)
95-100 F6.3 mag HGaia Gaia absolute magnitude
102-106 F5.3 mag e_HGaia Uncertainty in Gaia absolute magnitude
108-113 F6.3 mag dHG12a Transformation to HG12* absolute magnitude
115-120 F6.3 --- G1 G1 slope parameter from HG1G2 phase function
122-126 F5.3 --- e_G1 ? Uncertainty in G1 (1)
128-133 F6.3 --- G2 G2 slope parameter from HG1G2 phase function
135-139 F5.3 --- e_G2 ? Uncertainty in G2 (1)
141-145 F5.3 --- q Phase integral computed from G1 and G2
147-151 F5.3 --- e_q Uncertainty in phase integral
153-157 F5.3 --- pGaia ? Gaia geometric albedo computed from
diameter (if available)
159-163 F5.3 --- e_pGaia ? Uncertainty in Gaia geometric albedo
165-169 F5.3 --- A ? Bond albedo computed from q and pGaia
(if available)
171-175 F5.3 --- e_A ? Uncertainty in Bond albedo
177-181 F5.3 mag rms root mean square of the fit
183-188 F6.1 --- AIC Akaike Information Criterion
190-194 F5.3 --- b/acxi ? b to a axis ratio of ellipsoid fitted
to convex shape
196-200 F5.3 --- c/acxi ? c to a axis ratio of ellipsoid fitted
to convex shape
--------------------------------------------------------------------------------
Note (1): blank error values on slope parameters (G12, G1, or G2)
indicates an upper or lower limit.
--------------------------------------------------------------------------------
Acknowledgements:
Eric M. MacLennan, eric.maclennan(at)helsinki.fi
References:
Pentikainen et al., Paper II, 2026A&A...707A.132P 2026A&A...707A.132P, Cat. J/A+A/707/A132
(End) Patricia Vannier [CDS] 21-Jan-2026