M-type (22) Kalliope: High density and differentiated interior 

2021 ◽  
Author(s):  
Marin Ferrais ◽  
Pierre Vernazza ◽  
Laurent Jorda ◽  
Benoit Carry ◽  
Frédéric Vachier ◽  
...  
Keyword(s):  
Internal Structure ◽  
Adaptive Optics ◽  
Satellite Orbit ◽  
Complete Characterization ◽  
High Density ◽  
High Angular Resolution ◽  
Inversion Algorithm ◽  
Shape Modelling ◽  
3D Shape ◽  
Modelling Techniques

<p> </p> <p><strong>Introduction</strong></p> <p>Asteroid (22) Kalliope is the second largest M-type asteroid in the main-belt after (16) Psyche. Kalliope has a bright satellite (D ~ 28km), Linus, discovered in 2001 [Me01, Ma01]. Albeit being a privileged target for adaptive optics (AO) ground-based observations, its density remains elusive with values ranging between 2.4 and 3.7 g cm-<sup>3</sup> [Ma03, Dr21]. Here, we present a complete characterization of the topography, bulk density, and internal structure of Kalliope, as well as the dynamic of the system based on high angular resolution imaging observations performed with VLT/SPHERE as part of an ESO large programme (ID: 199.C-0074).</p> <p><strong>Observation</strong></p> <p>We obtained 35 images of Kalliope at 7 epochs near opposition between March and May 2018 and in June 2019 with the VLT/SPHERE/ZIMPOL AO instrument. The first apparition in 2018 covered the south pole of Kalliope while during the second it was close to an equator-on geometry. The north pole was not completely imaged, although 88% of the surface was covered at least once. We compiled 145 lightcurves from databases and we acquired new ones during the 2018 apparition to be used in the 3D shape modelling.</p> <p>For the determination of Linus’s orbit, we complemented the SPHERE images with a compilation of archival data from other large ground-based AO instruments (KeckII/NIRC2, ESO/VLT/NACO and Gemini-North/NIRI). We obtained a total of 82 measurements spanning 42 epochs from 2001 to 2019.</p> <p><strong>Methods</strong></p> <p>We generated shape models of Kalliope with three different shape modelling techniques. We first used the inversion algorithm ADAM [Vi15] and the genetic algorithm SAGE [B18, Du20] that both take lightcurves and AO images as inputs.</p> <p>We then applied our Multi-resolution PhotoClinometry by Deformation (MPCD; [C13, F20]) method on the SPHERE images to reconstruct Kalliope’s 3D shape, starting from both the ADAM and the SAGE models as initial meshes.</p> <p>To study the dynamic of the system, the relative position of Kalliope and Linus were first measured on the images. Then, we used the meta-heuristic algorithm Genoid [Va12] to accurately determine the orbital elements.</p> <p><strong>Results and conclusions</strong></p> <p>The volume of Kalliope from the different modelling techniques and the mass constrained by the precise measurements of its satellite orbit yield a density of ~4.1 g cm-<sup>3</sup>. This high density is comparable within errors to that of the metallic asteroid (16) Psyche. The best orbital solutions for the satellite are found when the quadrupole J2 tends toward 0. However, Kalliope’s shape implies a non-zero J2 when assuming a homogeneous interior density. This suggests an inhomogeneous, differentiated internal structure.</p> <p> </p> <p><strong>Bibliography</strong></p> <p>[B18] Bartczak, P. and Dudzinski, G. 2018, MNRAS, 473</p> <p>[C13] Capanna, C., Gesquière, G., Jorda, L., Lamy, P., & Vibert, D. 2013, The Visual Computer, 29, 825</p> <p>[Dr21] Drummond, J. D., Merline, W. J., Carry, B., et al. 2021, Icarus, 358</p> <p>[Du20] Dudzinski, G., Podlewska-Gaca, E., Bartczak, P., et al. 2020, MNRAS, 499</p> <p>[F20] Ferrais, M., Vernazza, P., Jorda, L., et al. 2020, A&A, 638, L15</p> <p>[Ma01] Margot, J. L. and Brown, M. E. 2001, IAU Circ., 7703, 3</p> <p>[Ma03] Margot, J. L. and Brown, M. E. 2003, Science, 300, 1939</p> <p>[Me01] Merline, W. J., Menard, F., Close, L., et al. 2001, IAU Circ., 7703, 2</p> <p>[Va12] Vachier, F., Berthier, J. and Marchis, F. 2012, A&1, 543, A68</p> <p>[Vi15] Viikinkoski, M., Kaasalainen, M., & Durech, J. 2015, A&A, 576, A8</p>

scholarly journals The impact crater at the origin of the Julia family detected with VLT/SPHERE?

2018 ◽  
Vol 618 ◽  
pp. A154 ◽  
Author(s):  
P. Vernazza ◽  
M. Brož ◽  
A. Drouard ◽  
J. Hanuš ◽  
M. Viikinkoski ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Adaptive Optics ◽  
Impact Crater ◽  
Large Fraction ◽  
Family Studies ◽  
High Angular Resolution ◽  
Main Belt ◽  
3D Shape ◽  
The Family ◽  
The Impact

Context. The vast majority of the geophysical and geological constraints (e.g., internal structure, cratering history) for main-belt asteroids have so far been obtained via dedicated interplanetary missions (e.g., ESA Rosetta, NASA Dawn). The high angular resolution of SPHERE/ZIMPOL, the new-generation visible adaptive-optics camera at ESO VLT, implies that these science objectives can now be investigated from the ground for a large fraction of D ≥ 100 km main-belt asteroids. The sharp images acquired by this instrument can be used to accurately constrain the shape and thus volume of these bodies (hence density when combined with mass estimates) and to characterize the distribution and topography of D ≥ 30 km craters across their surfaces. Aims. Here, via several complementary approaches, we evaluated the recently proposed hypothesis that the S-type asteroid (89) Julia is the parent body of a small compact asteroid family that formed via a cratering collisional event. Methods. We observed (89) Julia with VLT/SPHERE/ZIMPOL throughout its rotation, derived its 3D shape, and performed a reconnaissance and characterization of the largest craters. We also performed numerical simulations to first confirm the existence of the Julia family and to determine its age and the size of the impact crater at its origin. Finally, we utilized the images/3D shape in an attempt to identify the origin location of the small collisional family. Results. On the one hand, our VLT/SPHERE observations reveal the presence of a large crater (D ~ 75 km) in Julia’s southern hemisphere. On the other hand, our numerical simulations suggest that (89) Julia was impacted 30–120 Myrs ago by a D ~ 8 km asteroid, thereby creating a D ≥ 60 km impact crater at the surface of Julia. Given the small size of the impactor, the obliquity of Julia and the particular orientation of the family in the (a,i) space, the imaged impact crater is likely to be the origin of the family. Conclusions. New doors into ground-based asteroid exploration, namely, geophysics and geology, are being opened thanks to the unique capabilities of VLT/SPHERE. Also, the present work may represent the beginning of a new era of asteroid-family studies. In the fields of geophysics, geology, and asteroid family studies, the future will only get brighter with the forthcoming arrival of 30–40 m class telescopes like ELT, TMT, and GMT.

scholarly journals Homogeneous internal structure of CM-like asteroid (41) Daphne

2019 ◽  
Vol 623 ◽  
pp. A132 ◽  
Author(s):  
B. Carry ◽  
F. Vachier ◽  
J. Berthier ◽  
M. Marsset ◽  
P. Vernazza ◽  
...  
Keyword(s):  
Internal Structure ◽  
Adaptive Optics ◽  
Thermal Evolution ◽  
Asteroid Belt ◽  
High Angular Resolution ◽  
Satellite Orbits ◽  
Data Set ◽  
Shape Model ◽  
Very Large Telescope ◽  
C Complex

Context. CM-like asteroids (Ch and Cgh classes) are a major population within the broader C-complex, encompassing about 10% of the mass of the main asteroid belt. Their internal structure has been predicted to be homogeneous, based on their compositional similarity as inferred from spectroscopy and numerical modeling of their early thermal evolution. Aims. Here we aim to test this hypothesis by deriving the density of the CM-like asteroid (41) Daphne from detailed modeling of its shape and the orbit of its small satellite. Methods. We observed Daphne and its satellite within our imaging survey with the Very Large Telescope extreme adaptive-optics SPHERE/ZIMPOL camera and complemented this data set with earlier Keck/NIRC2 and VLT/NACO observations. We analyzed the dynamics of the satellite with our Genoid meta-heuristic algorithm. Combining our high-angular resolution images with optical lightcurves and stellar occultations, we determine the spin period, orientation, and 3D shape, using our ADAM shape modeling algorithm. Results. The satellite orbits Daphne on an equatorial, quasi-circular, prograde orbit, like the satellites of many other large main-belt asteroids. The shape model of Daphne reveals several large flat areas that could be large impact craters. The mass determined from this orbit combined with the volume computed from the shape model implies a density for Daphne of 1.77 ± 0.26 g cm−3 (3 σ). This densityis consistent with a primordial CM-like homogeneous internal structure with some level of macroporosity (≈ 17%). Conclusions. Based on our analysis of the density of Daphne and 75 other Ch/Cgh-type asteroids gathered from the literature, we conclude that the primordial internal structure of the CM parent bodies was homogeneous.

scholarly journals Volume uncertainty of (7) Iris shape models from disc-resolved images

2020 ◽  
Vol 499 (3) ◽  
pp. 4545-4560
Author(s):  
G Dudziński ◽  
E Podlewska-Gaca ◽  
P Bartczak ◽  
S Benseguane ◽  
M Ferrais ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Angular Resolution ◽  
The Body ◽  
High Angular Resolution ◽  
Shape Modelling ◽  
Shape Models ◽  
Uncertainty Calculation ◽  
Substantial Error ◽  
Error Bars ◽  
Inversion Techniques

ABSTRACT High angular resolution disc-resolved images of (7) Iris collected by VLT/SPHERE instrument are allowed for the detailed shape modelling of this large asteroid revealing its surface features. If (7) Iris did not suffer any events catastrophic enough to disrupt the body (which is very likely) by studying its topography, we might get insights into the early Solar system’s collisional history. When it comes to internal structure and composition, thoroughly assessing the volume and density uncertainties is necessary. In this work, we propose a method of uncertainty calculation of asteroid shape models based on light curve and adaptive optics (AO) images. We apply this method on four models of (7) Iris produced from independent Shaping Asteroids using Genetic Evolution and All-Data Asteroid Modelling inversion techniques and multiresolution photoclinometry by deformation. Obtained diameter uncertainties stem from both the observations from which the models were scaled and the models themselves. We show that despite the availability of high-resolution AO images, the volume and density of (7) Iris have substantial error bars that were underestimated in the previous studies.

Development of thin-shell adaptive optics for high angular resolution x-ray telescopes

2008 ◽  
Author(s):  
Charlotte Feldman ◽  
Richard Willingale ◽  
Carolyn Atkins ◽  
Hongchang Wang ◽  
Peter Doel ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Thin Shell ◽  
Angular Resolution ◽  
High Angular Resolution ◽  
X Ray

3D shape modelling of femur

2016 ◽  
Author(s):  
Dalila Cherifi ◽  
Imene Soual ◽  
Sabiha Omari ◽  
Amine Nait-Ali
Keyword(s):  
Shape Modelling ◽  
3D Shape

scholarly journals Fragmentation and dynamics in Massive Dense Cores in Cygnus-X

2010 ◽  
Vol 6 (S270) ◽  
pp. 53-56 ◽  
Author(s):  
T. Csengeri ◽  
S. Bontemps ◽  
N. Schneider ◽  
F. Motte
Keyword(s):  
Angular Resolution ◽  
High Density ◽  
High Mass ◽  
High Angular Resolution ◽  
Low Mass Stars ◽  
Dense Cores ◽  
Evolutionary Scenario ◽  
Low Mass ◽  
Molecular Tracers ◽  
Resolution Study

AbstractA systematic, high angular-resolution study of IR-quiet Massive Dense Cores (MDCs) of Cygnus-X in continuum and high-density molecular tracers is presented. The results are compared with the quasi-static and the dynamical evolutionary scenario. We find that the fragmentation properties are not compatible with the quasi-static, monolithic collapse scenario, nor are they entirely compatible with the formation of a cluster of mostly low-mass stars. The kinematics of MDCs shows individual velocity components appearing as coherent flows, which indicate important dynamical processes at the scale of the mass reservoir around high-mass protostars.

scholarly journals VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis

2021 ◽  
Vol 654 ◽  
pp. A56
Author(s):  
P. Vernazza ◽  
M. Ferrais ◽  
L. Jorda ◽  
J. Hanuš ◽  
B. Carry ◽  
...  
Keyword(s):  
Rotation Period ◽  
High Angular Resolution ◽  
Main Belt ◽  
Volume Estimate ◽  
Multiple Systems ◽  
3D Shape ◽  
Asteroid Exploration ◽  
Reconstruction Methods ◽  
C Complex ◽  
Compositional Diversity

Context. 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  ≥ 100 km) main-belt asteroids have remained poorly constrained. The improved capabilities of the SPHERE/ZIMPOL instrument have opened new doors into ground-based asteroid exploration. Aims. 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  ≥ 100 km and in particular most D  ≥ 200 km 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. Methods. 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. Results. 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 6 h and an elongated shape (c∕a ≤ 0.65). Densities in our sample range from ~1.3 g cm−3 (87 Sylvia) to ~4.3 g cm−3 (22 Kalliope). Furthermore, the density distribution appears to be strongly bimodal with volatile-poor (ρ ≥ 2.7 g cm−3) and volatile-rich (ρ ≤ 2.2 g cm−3) 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.

scholarly journals First scattered light detection of a nearly edge-on transition disk around the T Tauri star RY Lupi

2018 ◽  
Vol 614 ◽  
pp. A88 ◽  
Author(s):  
M. Langlois ◽  
A. Pohl ◽  
A.-M. Lagrange ◽  
A.- L. Maire ◽  
D. Mesa ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Near Infrared ◽  
Planet Formation ◽  
Scattered Light ◽  
Emission Feature ◽  
Point Sources ◽  
Tauri Star ◽  
Dual Band ◽  
High Angular Resolution ◽  
T Tauri

Context. Transition disks are considered sites of ongoing planet formation, and their dust and gas distributions could be signposts of embedded planets. The transition disk around the T Tauri star RY Lup has an inner dust cavity and displays a strong silicate emission feature. Aims. Using high-resolution imaging we study the disk geometry, including non-axisymmetric features, and its surface dust grain, to gain a better understanding of the disk evolutionary process. Moreover, we search for companion candidates, possibly connected to the disk. Methods. We obtained high-contrast and high angular resolution data in the near-infrared with the VLT/SPHERE extreme adaptive optics instrument whose goal is to study the planet formation by detecting and characterizing these planets and their formation environments through direct imaging. We performed polarimetric imaging of the RY Lup disk with IRDIS (at 1.6 μm), and obtained intensity images with the IRDIS dual-band imaging camera simultaneously with the IFS spectro-imager (0.9–1.3 μm). Results. We resolved for the first time the scattered light from the nearly edge-on circumstellar disk around RY Lup, at projected separations in the 100 au range. The shape of the disk and its sharp features are clearly detectable at wavelengths ranging from 0.9 to 1.6 μm. We show that the observed morphology can be interpreted as spiral arms in the disk. This interpretation is supported by in-depth numerical simulations. We also demonstrate that these features can be produced by one planet interacting with the disk. We also detect several point sources which are classified as probable background objects.

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