J/A+A/662/A71 (22) Kalliope SPHERE images and shape models (Ferrais+, 2022)
M-type (22) Kalliope: A tiny Mercury.
Ferrais M., Jorda L., Vernazza P., Carry B., Broz M., Rambaux N., Hanus J.,
Dudzinski G., Bartczak P., Vachier F., Aristidi E., Beck P., Marchis F.,
Marsset M., Viikinkoski M., Fetick R., Drouard A., Fusco T., Birlan M.,
Podlewska-Gaca E., Burbine T.H., Dyar M.D., Bendjoya P., Benkhaldoun Z.,
Berthier J., Castillo-Rogez J., Cipriani F., Colas F., Dumas C., Durech J.,
Fauvaud S., Grice J., Jehin E., Kaasalainen M., Kryszczynska A., Lamy P.,
Le Coroller H., Marciniak A., Michalowski T., Michel P., Prieur J.-L,
Reddy V., Rivet J.-P., Santana-Ros T., Scardia M., Tanga P., Vigan A.,
Witasse O., Yang B.
<Astron. Astrophys. 662, A71 (2022)>
=2022A&A...662A..71F 2022A&A...662A..71F (SIMBAD/NED BibCode)
ADC_Keywords: Solar system ; Minor planets ; Morphology
Keywords: minor planets, asteroids: individual: (22) Kalliope -
methods: observational - techniques: high angular resolution
Abstract:
Asteroid (22) Kalliope is the second largest M-type asteroid in the
main belt and is orbited by a satellite, Linus. Whereas the mass of
Kalliope is already well constrained thanks to the presence of a moon,
its volume is still poorly known, leading to uncertainties on its bulk
density and internal structure.
We aim at refining the shape of (22) Kalliope and thus its diameter
and bulk density, as well as the orbit of its moon to better constrain
its mass, hence density and internal structure.
We acquired disk-resolved observations of (22) Kalliope using the
VLT/SPHERE/ZIMPOL instrument to reconstruct its three-dimensional (3D)
shape using three different modeling techniques. These images were
also used together with new speckle observations at the C2PU/PISCO
instrument as well as archival images from other large ground-based
telescopes to refine the orbit of Linus.
The volume of (22) Kalliope given by the shape models, corresponding
to D=150±5km, and the mass constrained by its satellite's orbit
yield a density of ρ=4.40±0.46g/cm3. This high density
potentially makes (22) Kalliope the densest known small body in the
solar system. A macroporosity in the 10-25% range (as expected for
such mass/size), implies a grain density in the 4.8-5.9g/cm3 range.
Kalliope's high bulk density, along with its silicate-rich surface
implied by its low radar albedo, implies a differentiated interior
with metal contributing to most of the mass of the body.
Kalliope's high metal content (40-60%) along with its metal-poor
mantle makes it the smallest known Mercury-like body. A large impact
at the origin of the formation of the moon Linus is likely the cause
of its high metal content and density.
Description:
We obtained 35 images of Kalliope at 7 epochs in 2018 and 2019 using
VLT/SPHERE/ZIMPOL. All images were reduced following the procedure
described in Vernazza et al. (2018A&A...618A.154V 2018A&A...618A.154V).
objects:
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Planet Name H Diam i e a
mag km deg AU
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22 Kalliope 6.53 150 13.700494 0.09838130 2.91020240
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
spadam.dat 44 1 Spin parameter of the ADAM model
spmpadam.dat 44 1 Spin parameter of the MPCD-ADAM model
spmpsage.dat 44 1 Spin parameter of the MPCD-SAGE model
spsage.dat 44 1 Spin parameter of the SAGE model
kalliope_adam.obj 29 1202 ADAM shape model in OBJ format
kalliope_mpcd-adam.obj 49 3858 MPCD-ADAM shape model in OBJ format
kalliope_mpcd-sage.obj 35 3865 MPCD-SAGE shape model in OBJ format
kalliope_sage.obj 35 11533 SAGE shape model in OBJ format
list.dat 130 70 List of fits images
fits/* . 70 Individual fits images
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See also:
J/A+A/618/A154 : (89) Julia SPHERE/ZIMPOL images (Vernazza+, 2018)
J/A+A/619/L3 : (16) Psyche images (Viikinkoski+, 2018)
J/A+A/623/A6 : Vesta VLT/SPHERE/ZIMPOL images (Fetick+, 2019)
J/A+A/623/A132 : (41) Daphne SPHERE/ZIMPOL images (Carry+, 2019)
J/A+A/624/A121 : (7) Iris Deconvolved disk-resolved images (Hanus+, 2019)
J/A+A/633/A65 : (704) Interamnia images (Hanus+, 2020)
J/A+A/638/L15 : (16) Psyche. VLT/SPHERE images & shape models (Ferrais+, 2020)
J/A+A/641/A80 : (31) Euphrosyne R-band images (Yang+, 2020)
J/A+A/650/A129 : (87) Sylvia SPHERE images (Carry+, 2021)
J/A+A/653/A57 : (216) Kleopatra images (Marchis+, 2021)
http://astro.troja.mff.cuni.cz/projects/asteroids3D/web.php : DAMIT Home Page
Description of files: kalliope_adam.obj, kalliope_mpcd-adam.obj,
kalliope_mpcd-sage.obj, kalliope_sage.obj
First column:
Flag for vertices "v" or facets "f" line
Columns 2 to 4:
For vertices lines: Cartesian coordinates (x,y,z) of the vertex
For facet lines: Index of the three vertices in the triangular facet
Byte-by-byte Description of file: sp*.dat
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Bytes Format Units Label Explanations
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1- 8 F8.4 deg LongP Ecliptic longitude of the pole (J2000)
10- 15 F6.4 deg LatP Ecliptic latitude of the pole (J2000)
17- 26 F10.8 h Period Sidereal rotation period
28- 38 F11.3 d t0 Reference epoch (Julian date, JD)
40- 44 F5.1 deg phi0 Initial rotation angle for t0
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
11- 19 F9.5 deg DEdeg Declination of center (J2000)
21- 27 F7.5 arcsec/pix scale Scale of the image
29- 32 I4 --- Nx Number of pixels along X-axis
34- 37 I4 --- Ny Number of pixels along Y-axis
39- 61 A23 "datime" Obs.date Observation date
62- 65 I4 Kibyte size Size of FITS file
67-130 A64 --- FileName Name of FITS file, in subdirectory fits
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Acknowledgements:
Marin Ferrais, marin.ferrais(at)lam.fr
(End) Patricia Vannier [CDS] 23-Mar-2022