J/A+A/670/L25 Astrometric ISS/Cassini data of Saturn inner moons (Lainey+, 2023)
Characterising the interior of five inner Saturnian moons using
Cassini ISS data.
Lainey V., Rambaux N., Cooper N., Dahoumane R., Zhang Q.
<Astron. Astrophys. 670, L25 (2023)>
=2023A&A...670L..25L 2023A&A...670L..25L (SIMBAD/NED BibCode)
ADC_Keywords: Solar system ; Planets ; Positional data
Keywords: astrometry - planets and satellites: interiors
Abstract:
The Cassini-Huygens space mission provided a huge amount of data for
the Saturnian system. While the mission ended in September 2017, there
is still much information to be retrieved from the data.
Here, from their orbital motion, we infer the interior of the five
inner Saturnian moons, Atlas, Prometheus, Pandora, Janus, and
Epimetheus. Our results benefit from a recent study of the shape of
these moons, which provides a much better estimation of their 3D shape
and volume.
Using Cassini Imaging Science Subsystem (ISS) astrometric data, we
again reduced the Cassini ISS images with an improved shape modelling.
We then integrated the orbital motion of the inner Saturnian moons and
solved for a large set of physical parameters for this system,
including the masses and physical libration amplitudes of the moons.
We obtain a density value (in g/cm3 with a 1σ error bar based
on the digital terrain models and spherical harmonics available today)
of 0.3935±0.0033, 0.4873±0.0026, 0.5045±0.0017, 0.6233±0.0015,
and 0.6413±0.0002 for Atlas, Prometheus, Pandora, Epimetheus, and
Janus, respectively. We were able to determine the physical libration
amplitudes of Prometheus, Pandora, Epimetheus, and Janus to be
0.98±0.08, -5.2±0.7, -6.0±0.6, and -0.39±0.16 (degrees and
1σ error bar), respectively. Our solutions for Epimetheus and
Janus are in full agreement with a former estimation performed
directly from the measurement of the rotation of these two moons.
We confirm the large porosity of these five moons and their increase
in density as a function of their size. Our estimations of the
physical librations of Prometheus, Pandora, Janus, and Epimetheus are
consistent with a homogeneous interior, but for Pandora a
heterogeneous interior is also plausible.
Description:
This table provides the astrometric ISS/Cassini data of the five inner
moons of Saturn that were used throughout the present work.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
data.dat 410 2968 Astrometric ISS/Cassini data of the five inner
moons of Saturn
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See also:
J/A+AS/121/65 : 1990-1994 Saturn's satellites astrometry (Harper+ 1997)
J/A+AS/136/257 : Saturn's satellites in 1995/97 (Harper+ 1999)
J/A+AS/139/305 : Position of Saturn's satellites (1982-1988) (Veiga+, 1999)
J/A+A/422/377 : 1997-2000 Saturn's satellites astrometry (Qiao+, 2004)
J/A+A/493/1183 : Saturn major satellites observations (1874-2007)
(Desmars+, 2009)
J/AJ/136/2214 : Positions of Saturn and its satellites in 2002-2006
(Peng+, 2008)
J/AJ/149/27 : Cassini ISS astrometry of Saturnian satellites
(Cooper+, 2015)
J/other/KFNT/33.70 : Topocentric positions of Saturn's moons
(Yizhakevych+, 2017)
J/AJ/159/129 : 21 saturnian small moons brightness with ISS
(Hedman+, 2020)
J/ApJS/263/15 : Cassini Visual + IR obs. of Saturn + Jupiter
(Coulter+, 2022)
Byte-by-byte Description of file: data.dat
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Bytes Format Units Label Explanations
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1- 4 I4 yr Obs.year Year of observation (TDB)
6- 7 I2 "month" Obs.month Month of observation (TDB)
9- 10 I2 d Obs.day Day of observation (TDB)
12- 21 F10.8 d Obs.time Fraction of day of observation (TDB)
23- 30 F8.3 pix PAtlasS ?=0 Position of moon Atlas (sample)
32- 39 F8.3 pix PAtlasL ?=0 Position of moon Atlas (line)
41- 48 F8.3 pix PPrometheusS ?=0 Position of moon Prometheus (sample)
50- 57 F8.3 pix PPrometheusL ?=0 Position of moon Prometheus (line)
59- 66 F8.3 pix PPandoraS ?=0 Position of moon Pandora (sample)
68- 75 F8.3 pix PPandoraL ?=0 Position of moon Pandora (line)
77- 84 F8.3 pix PEpimetheusS ?=0 Position of moon Epimetheus (sample)
87- 93 F7.3 pix PEpimetheusL ?=0 Position of moon Epimetheus (line)
95-102 F8.3 pix PJanusS ?=0 Position of moon Janus (sample)
104-111 F8.3 pix PJanusL ?=0 Position of moon Janus (line)
121-136 F16.12 deg DirX Direction of the center of the camera frame
139-154 F16.12 deg DirY Direction of the center of the camera frame
157-172 F16.12 deg Twist Twist angle
175-183 F9.4 mm Flenght Focal length of the camera
193-199 F7.3 pix Xpos Center coordinate of the field of view
211-217 F7.3 pix Ypos Center coordinate of the field of view
243-248 F6.4 pix e_PAtlasS ?=0 1σ uncertainty on position of
moon Atlas (sample)
261-266 F6.4 pix e_PAtlasL ?=0 1σ uncertainty on position of
moon Atlas (line)
279-284 F6.4 pix e_PPrometheusS ?=0 1σ uncertainty on position of
moon Prometheus (sample)
297-302 F6.4 pix e_PPrometheusL ?=0 1σ uncertainty on position of
moon Prometheus (line)
315-320 F6.4 pix e_PPandoraS ?=0 1σ uncertainty on position of
moon Pandora (sample)
333-338 F6.4 pix e_PPandoraL ?=0 1σ uncertainty on position of
moon Pandora (line)
351-356 F6.4 pix e_PEpimetheusS ?=0 1σ uncertainty on position of
moon Epimetheus (sample)
369-374 F6.4 pix e_PEpimetheusL ?=0 1σ uncertainty on position of
moon Epimetheus (line)
387-392 F6.4 pix e_PJanusS ?=0 1σ uncertainty on position of
moon Janus (sample)
405-410 F6.4 pix e_PJanusL ?=0 1σ uncertainty on position of
moon Janus (line)
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Acknowledgements:
Valery Lainey, lainey(at)imcce.fr
(End) Patricia Vannier [CDS] 15-Feb-2023