scholarly journals A thermophysical and dynamical study of the Hildas (1162) Larissa and (1911) Schubart

2021 ◽  
Author(s):  
Cristian F Chavez ◽  
T G Müller ◽  
J P Marshall ◽  
J Horner ◽  
H Drass ◽  
...  
Keyword(s):  
Thermal Inertia ◽  
Infrared Camera ◽  
Asteroid Belt ◽  
Effective Diameter ◽  
Early Solar System ◽  
Dynamical Study ◽  
Axis Ratio ◽  
Ellipsoidal Shape ◽  
Dynamical Simulations ◽  
Taxonomical Classification

Abstract The Hilda asteroids are among the least studied populations in the asteroid belt, despite their potential importance as markers of Jupiter’s migration in the early Solar system. We present new mid-infrared observations of two notable Hildas, (1162) Larissa and (1911) Schubart, obtained using the Faint Object infraRed CAmera for the SOFIA Telescope (FORCAST), and use these to characterise their thermal inertia and physical properties. For (1162) Larissa, we obtain an effective diameter of 46.5$^{+2.3}_{-1.7}$ km, an albedo of 0.12 ± 0.02, and a thermal inertia of 15$^{+10}_{-8}$ Jm−2s1/2K−1. In addition, our Larissa thermal measurements are well matched with an ellipsoidal shape with an axis ratio a/b=1.2 for the most-likely spin properties. Our modelling of (1911) Schubart is not as refined, but the thermal data point towards a high-obliquity spin-pole, with a best-fit a/b=1.3 ellipsoidal shape. This spin-shape solution is yielding a diameter of 72$^{+3}_{-4}$ km, an albedo of 0.039± 0.02, and a thermal inertia below 30 Jm−2s1/2K−1 (or 10$^{+20}_{-5}$ Jm−2s1/2K−1). As with (1162) Larissa, our results suggest that (1911) Schubart is aspherical, and likely elongated in shape. Detailed dynamical simulations of the two Hildas reveal that both exhibit strong dynamical stability, behaviour that suggests that they are primordial, rather than captured objects. The differences in their albedos, along with their divergent taxonomical classification, suggests that despite their common origin, the two have experienced markedly different histories.

scholarly journals No evidence for interstellar planetesimals trapped in the Solar system

2020 ◽  
Vol 497 (1) ◽  
pp. L46-L49 ◽  
Author(s):  
A Morbidelli ◽  
K Batygin ◽  
R Brasser ◽  
S N Raymond
Keyword(s):  
Solar System ◽  
Oort Cloud ◽  
Giant Planets ◽  
Asteroid Belt ◽  
Interstellar Space ◽  
Fast Decay ◽  
Early Solar System ◽  
The Past ◽  
Solar System Bodies ◽  
Main Asteroid Belt

ABSTRACT In two recent papers published in MNRAS, Namouni and Morais claimed evidence for the interstellar origin of some small Solar system bodies, including: (i) objects in retrograde co-orbital motion with the giant planets and (ii) the highly inclined Centaurs. Here, we discuss the flaws of those papers that invalidate the authors’ conclusions. Numerical simulations backwards in time are not representative of the past evolution of real bodies. Instead, these simulations are only useful as a means to quantify the short dynamical lifetime of the considered bodies and the fast decay of their population. In light of this fast decay, if the observed bodies were the survivors of populations of objects captured from interstellar space in the early Solar system, these populations should have been implausibly large (e.g. about 10 times the current main asteroid belt population for the retrograde co-orbital of Jupiter). More likely, the observed objects are just transient members of a population that is maintained in quasi-steady state by a continuous flux of objects from some parent reservoir in the distant Solar system. We identify in the Halley-type comets and the Oort cloud the most likely sources of retrograde co-orbitals and highly inclined Centaurs.

Natural transportation routes in the Solar System

2019 ◽  
Vol 15 (S350) ◽  
pp. 471-473
Author(s):  
Nataša Todorović
Keyword(s):  
Solar System ◽  
Large Fraction ◽  
Outer Part ◽  
Asteroid Belt ◽  
Water Molecules ◽  
Early Solar System ◽  
Type Water ◽  
Transportation Routes

AbstractThe aim of this work is to explain the possible mechanism in the early Solar System, by which water-rich asteroids may have been delivered to Earth. Carbonaceous (C-type) asteroids, with a large fraction of water molecules, dominate in the outer part of the asteroid belt and the possibility of their migration toward Earth is still not well explained. In this work, we observe very efficient dynamical routes along which C-type water-bearing asteroids are delivered to Earth.

scholarly journals Dynamical Simulations: Methods and Comparisons

1998 ◽  
Vol 11 (2) ◽  
pp. 590-596 ◽  
Author(s):  
D.C. Heggie ◽  
Mirek Giersz ◽  
Rainer Spurzem ◽  
Koji Takahashi
Keyword(s):  
Star Clusters ◽  
Dynamical Models ◽  
Dynamical Study ◽  
Dynamical Simulations

In the dynamical study of globular star clusters, five types of dynamical models are in current use. The following list includes recent highlights, some of which are developed in these proceedings by other authors.

scholarly journals Arrival and magnetization of carbonaceous chondrites in the asteroid belt before 4562 million years ago

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Timothy O’Brien ◽  
John A. Tarduno ◽  
Atma Anand ◽  
Aleksey V. Smirnov ◽  
Eric G. Blackman ◽  
...  
Keyword(s):  
Solar System ◽  
Arrival Time ◽  
Carbonaceous Chondrite ◽  
Parent Body ◽  
Asteroid Belt ◽  
Carbonaceous Chondrites ◽  
Early Solar System ◽  
Outer Disk ◽  
Main Asteroid Belt ◽  
Insight Into

AbstractMeteorite magnetizations can provide rare insight into early Solar System evolution. Such data take on new importance with recognition of the isotopic dichotomy between non-carbonaceous and carbonaceous meteorites, representing distinct inner and outer disk reservoirs, and the likelihood that parent body asteroids were once separated by Jupiter and subsequently mixed. The arrival time of these parent bodies into the main asteroid belt, however, has heretofore been unknown. Herein, we show that weak CV (Vigarano type) and CM (Mighei type) carbonaceous chondrite remanent magnetizations indicate acquisition by the solar wind 4.2 to 4.8 million years after Ca-Al-rich inclusion (CAI) formation at heliocentric distances of ~2–4 AU. These data thus indicate that the CV and CM parent asteroids had arrived near, or within, the orbital range of the present-day asteroid belt from the outer disk isotopic reservoir within the first 5 million years of Solar System history.

The 3.1 μm absorption feature on asteroids (24) Themis and (65) Cybele is not due to surface water ice

2021 ◽  
Author(s):  
Laurence O'Rourke ◽  
Thomas G. Müller ◽  
Nicolas Biver ◽  
Dominique Bockelée-Morvan ◽  
Sunao Hasegawa ◽  
...  
Keyword(s):  
Surface Water ◽  
Line Emission ◽  
Thermal Inertia ◽  
Infrared Camera ◽  
Far Infrared ◽  
Subsurface Water ◽  
Absorption Feature ◽  
Water Ice ◽  
V Band ◽  
Thermophysical Model

<p>Previous research on Asteroids (24) Themis and (65) Cybele have shown the presence of an absorption feature at 3.1 μm reported to be directly linked to surface water ice. We searched for water vapor escaping from these asteroids with the Herschel Space Observatory HIFI (Heterodyne Instrument for the Far Infrared) Instrument. While no H<sub>2</sub>O line emission was detected, we obtained sensitive 3σ water production rate upper limits of Q(H<sub>2</sub>O)< 4.1×10<sup>26</sup> molecules s<sup>−1</sup> for Themis and Q(H<sub>2</sub>O) <7.6 × 10<sup>26</sup> molecules s<sup>−1</sup> for the case of Cybele. Using a thermophysical model, we merged data from the Subaru/Cooled Mid-Infrared Camera and Spectrometer and the Herschel SPIRE (Spectral and Photometric Imaging Receiver) instrument with the contents of a multi-observatory database and thus derived new radiometric properties for these two asteroids. For Themis, we obtained a thermal inertia G = 20 <sup>+25</sup><sub>-10</sub> J m<sup>−2</sup> s<sup>−1/2</sup> K<sup>−1</sup>, a diameter 192 <sup>+10</sup><sub>-7</sub> km, and a geometric V-band albedo p<sub>V</sub>=0.07±0.01. For Cybele, we found a thermal inertia G = 25<sup>+28</sup><sub>-19</sub> J m<sup>−2</sup> s<sup>−1/2</sup> K<sup>−1</sup>, a diameter 282±9 km, and an albedo pV=0.042±0.005. Using all inputs, we estimated that water ice intimately mixed with the asteroids’ dark surface material would cover <0.0017% (for Themis) and <0.0033% (for Cybele) of their surfaces, while an areal mixture with very clean ice (Bond albedo 0.8 for Themis and 0.7 for Cybele) would cover <2.2% (for Themis) and <1.5% (for Cybele) of their surfaces. Based on these very low percentage coverage values, it is clear that while surface (and subsurface) water ice may exist in small localized amounts on both asteroids, it is not the reason for the observed 3.1 μm absorption feature.</p>

scholarly journals THE ASTEROID BELT AS A RELIC FROM A CHAOTIC EARLY SOLAR SYSTEM

2016 ◽  
Vol 833 (1) ◽  
pp. 40 ◽  
Author(s):  
André Izidoro ◽  
Sean N. Raymond ◽  
Arnaud Pierens ◽  
Alessandro Morbidelli ◽  
Othon C. Winter ◽  
...  
Keyword(s):  
Solar System ◽  
Asteroid Belt ◽  
Early Solar System

scholarly journals The last pieces of the primitive inner belt puzzle: Klio, Chaldaea, Chimaera, and Svea

2019 ◽  
Vol 630 ◽  
pp. A141 ◽  
Author(s):  
David Morate ◽  
Julia de León ◽  
Mário De Prá ◽  
Javier Licandro ◽  
Noemí Pinilla-Alonso ◽  
...  
Keyword(s):  
Asteroid Belt ◽  
Main Belt ◽  
Absorption Bands ◽  
Aqueous Alteration ◽  
Visible Spectra ◽  
Main Asteroid Belt ◽  
Taxonomical Classification ◽  
Inner Region ◽  
Near Earth Asteroids

Aims. Several primitive families in the inner region of the main asteroid belt were identified as potential sources for two near-Earth asteroids (NEAs), (101955) Bennu and (162173) Ryugu, targets of the sample-return missions OSIRIS-REx and Hayabusa2, respectively. Four of the families, located at high proper inclinations (i > 10°), have not yet been compositionally studied: Klio, Chaldaea, Chimaera, and Svea. We want to characterize and analyze these families within the context of our PRIMitive Asteroid Spectroscopic Survey (PRIMASS), in order to complete the puzzle of the origins of the two NEAs. Methods. We obtained visible spectra (0.5–0.9 μm) of a total of 73 asteroids within the Klio, Chaldaea, Chimaera, and Svea collisional families, using the instrument OSIRIS at the 10.4 m Gran Telescopio Canarias. We performed a taxonomical classification of these objects, and an analysis of the possible presence of absorption bands related to aqueous alterations, comparing the results with already studied primitive families in the inner main belt. Results. We present here reflectance spectra for 30 asteroids in the Klio family, 15 in Chaldaea, 20 in Chimaera, and 8 in Svea. We show that Klio, Chaldaea, and Chimaera members have moderately red spectral slopes, with aqueous alteration absorption bands centered around 0.7 μm, characteristic of the group of primitive families known as Erigone-like. In contrast, Svea shows no 0.7 μm features, and neutral and blue spectral slopes, and thus is a Polana-like family. While all four families might be related to (162173) Ryugu, the only family studied in this work that might be related to (101955) Bennu is Svea.

scholarly journals Thermophysical Characteristics of OSIRIS-REx Target Asteroid (101955) Bennu

2015 ◽  
Vol 10 (S318) ◽  
pp. 218-220
Author(s):  
Liangliang Yu ◽  
Jianghui Ji
Keyword(s):  
Grain Size ◽  
Thermal Inertia ◽  
Effective Diameter ◽  
Thermophysical Characteristics ◽  
Shape Model ◽  
Infrared Observations ◽  
Fine Grained ◽  
Thermophysical Model ◽  
Best Fit ◽  
Geometric Albedo

AbstractIn this work, we investigate the thermophysical properties, including thermal inertia, roughness fraction and surface grain size of OSIRIS-REx target asteroid (101955) Bennu by using a thermophysical model with the recently updated 3D radar-derived shape model (Nolan et al., 2013) and mid-infrared observations (Müller et al. 2012, Emery et al., 2014). We find that the asteroid bears an effective diameter of 510+6−40 m, a geometric albedo of 0.047+0.0083−0.0011, a roughness fraction of 0.04+0.26−0.04, and thermal inertia of 240+440−60 Jm−2s−0.5K−1 for our best-fit solution. The best-estimate thermal inertia suggests that fine-grained regolith may cover a large portion of Bennu's surface, where a grain size may vary from 1.3 to 31 mm. Our outcome suggests that Bennu is suitable for the OSIRIS-REx mission to return samples to Earth.

Characterisation of V-type asteroids orbiting in the middle and outer main belt

2021 ◽  
Author(s):  
Alessandra Migliorini ◽  
M C De Sanctis ◽  
T A Michtchenko ◽  
D Lazzaro ◽  
M Barbieri ◽  
...  
Keyword(s):  
Near Infrared ◽  
Moving Objects ◽  
Outer Part ◽  
Parent Body ◽  
Sloan Digital Sky Survey ◽  
Asteroid Belt ◽  
Main Belt ◽  
Fe Content ◽  
Principal Finding ◽  
Taxonomical Classification

Abstract We present new spectral observations using ground-based telescopes of 23 putative V-type asteroids, selected according to colour surveys in the visible from the Moving Objects Catalogue of the Sloan Digital Sky Survey and near-infrared from the Moving Objects VISTA catalogue. Ten asteroids are orbiting in the middle main belt, while five in the outer part of the main asteroid belt. For the observed asteroids we assign a taxonomical classification and confirm the basaltic nature for sixteen of them. The high-quality spectra in the UV range, obtained with the X-Shooter spectrograph at ESO, allowed the identification of the Fe2 + forbidden transition of pyroxene for ten asteroids. This band is centred at 506.5 nm, and it is diagnostic of the Ca-content in the pyroxene form. We determined a low Fe-content composition for asteroids (2452) Lyot, (5758) Brunini, (7675) Gorizia, (9197) Endo, (22308) 1990 UO4, (36118) 1999 RE135, (66905) 1999 VC160, and (189597) 2000 WG119, and a composition more rich in Fe for asteroids (75661) 2000 AB79 and (93620) 2000 UQ70. We also present a dynamical investigation of V-type asteroids in the middle and outer main belt. The principal finding of these simulations is that the middle and outer V-types are more likely to be associated with some families, which were considered as possibly originated from the break-up of a partially or totally differentiated parent body by diverse studies. This reinforces the hypothesis that the identified V-type in the region were not originated from (4) Vesta and that the number of differentiated objects in the middle and outer main belt must have been much larger than previously assumed.

Towards 3D modelling of convection in planetesimals and meteorite parent bodies

2019 ◽  
Vol 490 (1) ◽  
pp. L47-L51 ◽  
Author(s):  
Wladimir Neumann
Keyword(s):  
Solid State ◽  
Thermal Evolution ◽  
Asteroid Belt ◽  
Magma Ocean ◽  
Early Solar System ◽  
Conduction Model ◽  
Time Requirements ◽  
Convection Model ◽  
Magma Oceans ◽  
Free Material

ABSTRACT Observations of asteroid belt members, investigations of meteorites and thermal evolution models converge on the paradigm of the ubiquity of melting processes in the planetesimals of the early Solar system. At least partial melting of planetesimals that fulfilled size and accretion time requirements to surpass the solidus temperatures of metal and silicates led to the weakening of the rock due to the interstitial melt. A decrease of the viscosity relative to melt-free material facilitates solid-state convection on partially molten bodies. Additional melting can produce liquid-like layers with suspended particles, i.e. magma oceans. Thermal evolution models indicate that partially molten layers can occur in the interior of undifferentiated bodies and in silicate mantles of differentiated ones. They can exist before a magma ocean forms or after it solidifies and above a whole-mantle magma ocean or below a shallow magma ocean. Thus, convection is likely. Attempts to model and to quantify the effects of convection in planetesimals remain rare. This study discusses the possibility of solid-state convection in partially molten planetesimals, presents a first-order comparison of a 3D mantle convection model with a conduction model taking a Vesta-sized body as an example and illustrates the importance of convection for meteorite parent bodies.

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