J/A+A/654/A56 Largest main belt asteroids data (Vernazza+, 2021)
VLT/SPHERE imaging survey of the largest main belt asteroids:
Final results and synthesis.
Vernazza P., Ferrais M., Jorda L., Hanua J., Carry B., Marsset M., Broz M.,
Fetick R., Viikinkoski M., Marchis F., Vachier F., Drouard A., Fusco T.,
Birlan M., Podlewska-Gaca E., Rambaux N., Neveu M., Bartczak P.,
Dudzinski G., Jehin E., Beck P., Berthier J., Castillo-Rogez J.,
Cipriani F., Colas F., Dumas C., Durech J., Grice J., Kaasalainen M.,
Kryszczynska A., Lamy P., Le Coroller H., Marciniak A., Michalowski T.,
Michel P., Santana-Ros T., Tanga P., Vigan A., Witasse O., Yang B.,
Antonini P., Audejean M., Aurard P., Behrend R., Benkhaldoun Z., Bosch J.M.,
Chapman A., Dalmon L., Fauvaud S., Hamanowa Hiroko, Hamanowa Hiromi,
His J., Jones A., Kim D-H., Kim M-J., Krajewski J., Labrevoir O., Leroy A.,
Livet F., Molina D., Montaigut R., Oey J., Payre N., Reddy V., Sabin P.,
Sanchez A.G., Socha L.
<Astron. Astrophys. 654, A56 (2021)>
=2021A&A...654A..56V 2021A&A...654A..56V (SIMBAD/NED BibCode)
ADC_Keywords: Minor planets
Keywords: minor planets, asteroids: general - methods: observational -
techniques: high angular resolution
Abstract:
Until recently, the 3D shape, and therefore density (when combining
the volume estimate with available mass estimates), and surface
topography of the vast majority of the largest (D≥100km) main-belt
asteroids have remained poorly constrained. The improved capabilities
of the SPHERE/ZIMPOL instrument have opened new doors into
ground-based asteroid exploration.
To constrain the formation and evolution of a representative sample of
large asteroids, we conducted a high-angular-resolution imaging survey
of 42 large main-belt asteroids with VLT/SPHERE/ZIMPOL. Our asteroid
sample comprises 39 bodies with D≥100km and in particular most
D≥200km main-belt asteroids (20/23). Furthermore, it nicely reflects
the compositional diversity present in the main belt as the sampled
bodies belong to the following taxonomic classes: A, B, C, Ch/Cgh,
E/M/X, K, P/T, S, and V.
The SPHERE/ZIMPOL images were first used to reconstruct the 3D shape
of all targets with both the ADAM and MPCD reconstruction methods. We
subsequently performed a detailed shape analysis and constrained the
density of each target using available mass estimates including our
own mass estimates in the case of multiple systems.
The analysis of the reconstructed shapes allowed us to identify two
families of objects as a function of their diameters, namely
"spherical" and "elongated" bodies. A difference in rotation period
appears to be the main origin of this bimodality. In addition, all but
one object (216 Kleopatra) are located along the Maclaurin sequence
with large volatile-rich bodies being the closest to the latter. Our
results further reveal that the primaries of most multiple systems
possess a rotation period of shorter than 6h and an elongated shape
(c/a≤0.65). Densities in our sample range from ∼1.3g/cm3
(87 Sylvia) to ∼4.3g/cm3 (22 Kalliope). Furthermore, the density
distribution appears to be strongly bimodal with volatile poor
(ρ≥2.7g/cm3) and volatile-rich (ρ≥2.2g/cm3) bodies.
Finally, our survey along with previous observations provides evidence
in support of the possibility that some C-complex bodies could be
intrinsically related to IDP-like P- and D-type asteroids,
representing different layers of a same body (C: core; P/D: outer
shell). We therefore propose that P/ D-types and some C-types may have
the same origin in the primordial trans-Neptunian disk.
Description:
The baseline observational strategy adopted for our large programme
has been to image each target with SPHERE/ZIMPOL (i) around opposition
to ensure an optimal spatial resolution (we restricted the observing
period so that its angular diameter remained greater than at least 85%
of that at opposition), (ii) every ∼60° in rotation phase in order
to obtain a satisfactory surface coverage, and (iii) with seeing
conditions of better than 0.8" and an airmass of below 1.6 in order to
ensure great observing conditions and thus high-quality data. To
fulfil these criteria and given that large programmes have the highest
priority at ESO, we performed our large programme entirely in service
mode. We would like to stress that this strategy has been key to the
success of our programme.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 80 42 Taxonomic type, volume-equivalent diameter (D),
mass (m), density (), geometric albedo, and
c/a ratio of our large programme targets
tablea2.dat 66 961 VLT/SPHERE disk-resolved images obtained by the
ZIMPOL camera
tablea3.dat 155 1184 *Optical disk-integrated data used for the
shape modeling
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Note on tablea3.dat: We only list light curves that have not been published or
that have not been a subject of a shape modeling study (i.e., light curves
are not available in DAMIT).
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Num Asteroid number
5- 14 A10 --- Name Asteroid name
16 A1 --- n_Name [*] * for bodies visited by spacecraft
18- 21 A4 -- Class Taxonomic type
23- 25 A3 --- F/S [F/S ] Collisional family (F) or that
possess one or two satellites (S)
27- 31 F5.1 km D Volume-equivalent diameter
33- 36 F4.1 km e_D Volume-equivalent diameter error (1 σ)
38- 43 F6.2 10+18kg m Mass
44- 48 F5.2 10+18kg e_m Mass error (1 σ)
50- 54 F5.3 g/cm3 rho Density
56- 60 F5.3 g/cm3 e_rho Density error (1 σ)
62- 66 F5.3 --- Albedo Albedo
68- 73 F6.4 --- c/a Oblateness
75- 80 F6.4 --- e_c/a Oblateness error (1 σ)
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1 A1 --- --- [(]
2- 4 I3 --- Num Asteroid number
5 A1 --- --- [)]
7- 16 A10 --- Name Asteroid name
18- 27 A10 "date" Obs.Date Observation date
29- 36 A8 "h:m:s" Obs.Time Observation time (UT)
38- 40 I3 s ExpTime Exposure time
42- 45 F4.2 --- Airmass Airmass
47- 50 F4.2 AU Delta Distance to the Earth
52- 55 F4.2 AU r Distance to the Sun
57- 60 F4.1 deg alpha Phase angle
62- 66 F5.3 arcsec Da Angular diameter of Kalliope
as seen from the Earth
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Byte-by-byte Description of file: tablea3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- --- [(]
2- 4 I3 --- Num Asteroid number
5 A1 --- --- [)]
7- 16 A10 --- Name Asteroid name
18- 29 A12 "date" Epoch Epoch
32- 35 I4 --- Np Number of individual measurements
37- 40 F4.2 AU Delta Asteroid's distance to the Earth
42- 45 F4.2 AU r Asteroid's distance to the Sun
47- 50 F4.1 deg phi Phase angle
52- 53 A2 --- Filter Photometric filter
56-155 A100 --- Ref Reference or, for new data, either
the observer, the telescope, or the
campaign name instead of the reference (1)
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Note (1): References as follows:
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Acknowledgements:
Pierre Vernazza, pierre.vernazza(at)lam.fr
(End) Patricia Vannier [CDS] 14-Sep-2021