Asteroid collisions as origin of debris disks: Asteroid shape reconstruction from BNAO Rozhen photometry

2019 ◽  
Vol 15 (S350) ◽  
pp. 451-453
Author(s):  
G. Apostolovska ◽  
E. Vchkova Bebekovska ◽  
A. Kostov ◽  
Z. Donchev
Keyword(s):  
Laboratory Experiments ◽  
Extrasolar Planets ◽  
Shape Reconstruction ◽  
Inversion Method ◽  
Debris Disks ◽  
Shape Parameters ◽  
Zodiacal Cloud ◽  
Photometric Observations ◽  
Different Shapes ◽  
Asteroid Surface

AbstractAs a result of collisions during their lifetimes, asteroids have a large variety of different shapes. It is believed that high velocity collisions or rotational spin-up of asteroids continuously replenish the Sun’s zodiacal cloud and debris disks around extrasolar planets (Jewitt (2010)). Knowledge of the spin and shape parameters of the asteroids is very important for understanding collision asteroid processes. Lately photometric observations of asteroids showed that variations in brightness are not accompanied by variations in colour index which indicate that the shape of the lightcurve is caused by varying illuminations of the asteroid surface rather than albedo variations over the surface. This conclusion became possible when photometric investigations were combined with laboratory experiments (Dunlap (1971)). In this article using the convex lightcurve inversion method we obtained the sense of rotation, pole solutions and preliminary shape of 901 Brunsia.

scholarly journals Photometry and shape modeling of Mars crosser asteroid (1011) Laodamia

2014 ◽  
pp. 79-85 ◽  
Author(s):  
G. Apostolovska ◽  
Z. Donchev ◽  
A. Kostov ◽  
V. Ivanova ◽  
G. Borisov ◽  
...  
Keyword(s):  
Sparse Data ◽  
Astronomical Observatory ◽  
Shape Modeling ◽  
Inversion Method ◽  
Shape Parameters ◽  
Spin Vector ◽  
Shape Model ◽  
Photometric Observations ◽  
Vector Sense

An analysis of photometric observations of Mars crosser asteroid 1011 Laodamia conducted at Bulgarian National Astronomical Observatory Rozhen over a twelve year interval (2002, 2003, 2004, 2006, 2007, 2008, 2011, 2012 and 2013) is made. Based on the obtained lightcurves the spin vector, sense of rotation, and preliminary shape model of (1011) Laodamia have been determined using the lightcurve inversion method. The aim of this investigation is to increase the set of asteroids with known spin and shape parameters and to contribute in improving the model in combination with other techniques and sparse data produced by photometric asteroid surveys such as Pan-STARRS or GAIA.

WISE data and sparse photometry used for shape reconstruction of asteroids

2015 ◽  
Vol 10 (S318) ◽  
pp. 170-176 ◽  
Author(s):  
Josef Ďurech ◽  
Josef Hanuš ◽  
Victor M. Alí-Lagoa ◽  
Marco Delbo ◽  
Dagmara A. Oszkiewicz
Keyword(s):  
Rotation Period ◽  
Shape Reconstruction ◽  
Physical Models ◽  
Inversion Method ◽  
Wide Field ◽  
Reflected Light ◽  
Space Data ◽  
Spin Determination ◽  
Infrared Survey

AbstractAsteroid disk-integrated sparse-in-time photometry can be used for determination of shapes and spin states of asteroids by the lightcurve inversion method. To clearly distinguish the correct solution of the rotation period from other minima in the parameter space, data with good photometric accuracy are needed. We show that if the low-quality sparse photometry obtained from ground-based astrometric surveys is combined with data from the Wide-field Infrared Survey Explorer (WISE) satellite, the correct rotation period can be successfully derived. Although WISE observed in mid-IR wavelengths, we show that for the period and spin determination, these data can be modelled as reflected light. The absolute fluxes are not required since only relative variation of the flux over the rotation is sufficient to determine the period. We also discuss the potential of combining all WISE data with the Lowell photometric database to create physical models of thousands of asteroids.

scholarly journals Characterizing the Orbital Eccentricities of Transiting Extrasolar Planets with Photometric Observations

2008 ◽  
Vol 678 (2) ◽  
pp. 1407-1418 ◽  
Author(s):  
Eric B. Ford ◽  
Samuel N. Quinn ◽  
Dimitri Veras
Keyword(s):  
Extrasolar Planets ◽  
Photometric Observations

scholarly journals A Simple Quantitative Inversion Approach for Microwave Imaging in Embedded Systems

2015 ◽  
Vol 2015 ◽  
pp. 1-18 ◽  
Author(s):  
M. Ambrosanio ◽  
R. Scapaticci ◽  
L. Crocco
Keyword(s):  
Real Time ◽  
Quantitative Imaging ◽  
Impedance Matching ◽  
Field Approximation ◽  
Microwave Imaging ◽  
Point Of View ◽  
Inversion Method ◽  
Linear Inversion ◽  
Imaging Results ◽  
Different Shapes

In many applications of microwave imaging, there is the need of confining the device in order to shield it from environmental noise as well as to host the targets and the medium used for impedance matching purposes. For instance, in MWI for biomedical diagnostics a coupling medium is typically adopted to improve the penetration of the probing wave into the tissues. From the point of view of quantitative imaging procedures, that is aimed at retrieving the values of the complex permittivity in the domain under test, the presence of a confining structure entails an increase of complexity of the underlying modelling. This entails a further difficulty in achieving real-time imaging results, which are obviously of interest in practice. To address this challenge, we propose the application of a recently proposed inversion method that, making use of a suitable preprocessing of the data and a scenario-oriented field approximation, allows obtaining quantitative imaging results by means of quasi-real-time linear inversion, in a range of cases which is much broader than usual linearized approximations. The assessment of the method is carried out in the scalar 2D configuration and taking into account enclosures of different shapes and, to show the method’s flexibility different shapes, embedding nonweak targets.

scholarly journals Selective Aggregation Experiments on Planetesimal Formation and Mercury-Like Planets

Geosciences ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 310 ◽  
Author(s):  
Gerhard Wurm
Keyword(s):  
Tensile Strength ◽  
High Temperature ◽  
Magnetic Fields ◽  
Laboratory Experiments ◽  
Extrasolar Planets ◽  
Protoplanetary Disks ◽  
Static Tensile ◽  
Selective Processing ◽  
Selective Aggregation ◽  
Initial Process

Much of a planet’s composition could be determined right at the onset of formation. Laboratory experiments can constrain these early steps. This includes static tensile strength measurements or collisions carried out under Earth’s gravity and on various microgravity platforms. Among the variety of extrasolar planets which eventually form are (Exo)-Mercury, terrestrial planets with high density. If they form in inner protoplanetary disks, high temperature experiments are mandatory but they are still rare. Beyond the initial process of hit-and-stick collisions, some additional selective processing might be needed to explain Mercury. In analogy to icy worlds, such planets might, e.g., form in environments which are enriched in iron. This requires methods to separate iron and silicate at early stages. Photophoresis might be one viable way. Mercury and Mercury-like planets might also form due to the ferromagnetic properties of iron and mechanisms like magnetic aggregation in disk magnetic fields might become important. This review highlights some of the mechanisms with the potential to trigger Mercury formation.

Modeling asteroid shapes using BNAO Rozhen photometric data in combination with sparse data

2021 ◽  
Author(s):  
Gordana Apostolovska ◽  
Elena Vchkova Bebekovska ◽  
Galin Borisov ◽  
Andon Kostov ◽  
Zahary Donchev
Keyword(s):  
Weather Conditions ◽  
Sparse Data ◽  
Space Mission ◽  
Physical Characteristics ◽  
Photometric Data ◽  
Inversion Method ◽  
Physical Parameters ◽  
Minor Planets ◽  
Photometric Observations ◽  
Dense Data

<p>Our work aims to demonstrate how the use of our dense lightcurves in combination with sparse data from diverse sources will affect the results for obtaining the sidereal period, shape models, and ecliptic pole solution for a chosen asteroid.</p> <p>Photometric observations of minor planets are traditional at the Bulgarian National Astronomical observatory (BNAO) Rozhen. They started with photoelectric observations in 1991, and later have been continued as CCD photometric observations on all three telescopes: 2m Ritchey-Chretién-Coudé, 50cm/70cm, and 60cm Cassegrain. We hope that the new 1.5 m robotic telescope planned to be operational next year will be also partly devoted to the study of minor planets.</p> <p>Our target, 339 Dorothea, is a main-belt asteroid, a large member of the Eos dynamical family. For the last 8 years, between 2013 and 2021, the asteroid 339 Dorothea was observed at BNAO Rozhen during six apparitions and several dense lightcurve were obtained. We used these dense photometric data in lightcurve inversion method and reconstruct the model of the asteroid, determining its sidereal period, shape, and pole orientation. Afterward, using sparse data from the AstDys database with an accuracy of 0.01 mag in combination with the obtained dense data, new trials for calculating and improving the physical characteristics of the asteroid 339 Dorothea were made.</p> <p>Unlike very low photometric accuracy in ground-based sparse photometry, space missions have provided astronomers with sparse photometry with extremely high accuracy, for example, the ESA GAIA mission. The NEOWISE mission has observations only for a limited number of asteroids. Fortunately, we were able to find some sparse data for our target and use this accurate photometry in combination with our dense lightcurves for the reconstruction of the asteroid spin state and shape model.</p> <p>Due to bad weather conditions and limited allocation of observing time at the BNAO Rozhen dedicated to our project, we have at our disposal full and partial dense lightcurves obtained for several more asteroids in few different apparitions. Combining these dense data with ground-based or space mission sparse data will contribute to enlarging the database of asteroids with known physical characteristics. Enriching the number of asteroids with known physical parameters would provide more data for future statistical analysis and could help in answering the questions for the evolution of our Solar System. </p>

Shape and spin of asteroid 967 Helionape

2017 ◽  
Vol 12 (S330) ◽  
pp. 393-394
Author(s):  
G. Apostolovska ◽  
A. Kostov ◽  
Z. Donchev ◽  
E. Vchkova Bebekovska ◽  
O. Kuzmanovska
Keyword(s):  
Family Member ◽  
Planetary System ◽  
Sparse Data ◽  
Astronomical Observatory ◽  
Inversion Method ◽  
Shape Parameters ◽  
Spin Vector ◽  
Main Belt ◽  
Shape Model ◽  
Geometric Conditions

AbstractKnowledge of the spin and shape parameters of the asteroids is very important for understanding of the conditions during the creation of our planetary system and formation of asteroid populations. The main belt asteroid and Flora family member 967 Helionape was observed during five apparitions. The observations were made at the Bulgarian National Astronomical Observatory (BNAO) Rozhen, since March 2006 to March 2016. Lihtcurve inversion method (Kaasalainen et al. (2001)), applied on 12 relative lightcurves obtained at various geometric conditions of the asteroid, reveals the spin vector, the sense of rotation and the preliminary shape model of the asteroid. Our aim is to contribute in increasing the set of asteroids with known spin and shape parameters. This could be done with dense lightcurves, obtained during small number of apparitions, in combination with sparse data produced by photometric asteroid surveys such as the Gaia satellite (Hanush (2011)).

Flexural Capacities of One-Way Hollow Slab with Donut Type Hollow Sphere

2010 ◽  
Vol 452-453 ◽  
pp. 773-776 ◽  
Author(s):  
Byoung Hoon Kim ◽  
Joo Hong Chung ◽  
Hyun Ki Choi ◽  
Seung Chang Lee ◽  
Chang Sik Choi
Keyword(s):  
Hollow Sphere ◽  
Hollow Spheres ◽  
Building Structures ◽  
Shape Parameters ◽  
Fiber Plastic ◽  
Test Parameters ◽  
Rc Slab ◽  
Different Shapes ◽  
Flexural Tests ◽  
The One

This paper presents the flexural capacities of one-way hollow slab with donut type hollow sphere. Recently, various types of slab systems which can reduce self-weight of slabs have been studied as the height and width of building structures rapidly increase. A biaxial hollow slab system is widely known as one of the effective slab system which can reduce self-weight of slab. A biaxial hollow slab has hollow spheres within slabs in order to reduce self-weight of slabs. The capacities of biaxial hollow slab are influenced by the shapes, volume and materials of hollow spheres. According to analytical studies, the hollow slab with donut type hollow sphere had good flexural capacities such as strength, stiffness and deflection. To verify the flexural capacities of this hollow slab, flexural tests were performed on the one-way hollow slabs. Five test specimens were used for test parameters. One was conventional RC slab and others were hollow slabs. The test parameters included two different shapes and materials of plastic balls. The shape parameters were donut and non-donut forms. And the material parameters were general plastic and glass fiber plastic.

scholarly journals Laboratory experiments on whirlpools

1948 ◽  
Vol 194 (1038) ◽  
pp. 398-415 ◽  
Keyword(s):  
Laboratory Experiments ◽  
Tangential Velocity ◽  
Approximate Theory ◽  
Open Circular ◽  
Different Shapes

Two vertical pipes, placed on the axis of an open circular tank and fitted with trumpet entries of different shapes, were used in turn as overflows. Water was led into the tank in such a way that the stream approaching the trumpet under test possessed tangential velocity, which caused a vortex to appear in and above the trumpet. The relations between head and discharge were determined under various conditions of tangential supply. The formation of a vortex greatly reduced the discharge, the decrease being even more marked with the shallow than with the deep trumpet. At low heads, where the flow was controlled by the weir action of the trumpet crest, the discharge varied with the shape of the crest as well as with the irrotational constant c and the head, therefore (as with purely radial supply) it must be determined by experiment. At high heads with the trumpet flooded, the throat controlled the flow; within certain limits, the discharge was dependent chiefly upon c and the head measured with the throat as datum, and an approximate theory which ignores friction was verified. Two types of instability, ‘surging’ at low heads and ‘spluttering’ at high heads, were examined. Both were due to the collapse and subsequent re-formation of feeble vortices, which caused the discharge to vary with time in a periodic manner.

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