scholarly journals Physical parameters of selected Gaia mass asteroids

2020 ◽  
Vol 638 ◽  
pp. A11
Author(s):  
E. Podlewska-Gaca ◽  
A. Marciniak ◽  
V. Alí-Lagoa ◽  
P. Bartczak ◽  
T. G. Müller ◽  
...  
Keyword(s):  
Thermal Inertia ◽  
Physical Property ◽  
Physical Parameters ◽  
Good Precision ◽  
Main Belt ◽  
Shape Models ◽  
Solar System Bodies ◽  
Fundamental Physical Property ◽  
Thermophysical Modeling ◽  
The Masses

Context. Thanks to the Gaia mission, it will be possible to determine the masses of approximately hundreds of large main belt asteroids with very good precision. We currently have diameter estimates for all of them that can be used to compute their volume and hence their density. However, some of those diameters are still based on simple thermal models, which can occasionally lead to volume uncertainties as high as 20–30%. Aims. The aim of this paper is to determine the 3D shape models and compute the volumes for 13 main belt asteroids that were selected from those targets for which Gaia will provide the mass with an accuracy of better than 10%. Methods. We used the genetic Shaping Asteroids with Genetic Evolution (SAGE) algorithm to fit disk-integrated, dense photometric lightcurves and obtain detailed asteroid shape models. These models were scaled by fitting them to available stellar occultation and/or thermal infrared observations. Results. We determine the spin and shape models for 13 main belt asteroids using the SAGE algorithm. Occultation fitting enables us to confirm main shape features and the spin state, while thermophysical modeling leads to more precise diameters as well as estimates of thermal inertia values. Conclusions. We calculated the volume of our sample of main-belt asteroids for which the Gaia satellite will provide precise mass determinations. From our volumes, it will then be possible to more accurately compute the bulk density, which is a fundamental physical property needed to understand the formation and evolution processes of small Solar System bodies.

scholarly journals Thermal properties of large main-belt asteroids observed by Herschel PACS

2020 ◽  
Vol 638 ◽  
pp. A84
Author(s):  
V. Alí-Lagoa ◽  
T. G. Müller ◽  
C. Kiss ◽  
R. Szakáts ◽  
G. Marton ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Thermal Inertia ◽  
Physical Models ◽  
Absolute Calibration ◽  
Calibration Error ◽  
Main Belt ◽  
Infrared Observations ◽  
Fine Grained ◽  
Shape Models ◽  
First Time

Non-resolved thermal infrared observations enable studies of thermal and physical properties of asteroids via thermo-physical models provided the shape and rotational properties of the target are well determined. We used calibration-programme Herschel PACS data (70, 100, 160 μm) and state-of-the-art shape models derived from adaptive-optics observations and/or optical light curves to constrain for the first time the thermal inertia of twelve large main-belt asteroids. We also modelled previously well-characterised targets such as (1) Ceres or (4) Vesta as they constitute important benchmarks. Using the scale as a free parameter, most targets required a re-scaling ~5% consistent with what would be expected given the absolute calibration error bars. This constitutes a good cross-validation of the scaled shape models, although some targets required larger re-scaling to reproduce the IR data. We obtained low thermal inertias typical of large main belt asteroids studied before, which continues to give support to the notion that these surfaces are covered by fine-grained insulating regolith. Although the wavelengths at which PACS observed are longwards of the emission peak for main-belt asteroids, they proved to be extremely valuable to constrain size and thermal inertia and not too sensitive to surface roughness. Finally, we also propose a graphical approach to help examine how different values of the exponent used for scaling the thermal inertia as a function of heliocentric distance (i.e. temperature) affect our interpretation of the results.

MULTIVERSE COSMOLOGICAL MODELS

2004 ◽  
Vol 19 (10) ◽  
pp. 727-743 ◽  
Author(s):  
P. C. W. DAVIES
Keyword(s):  
String Theory ◽  
Selection Effect ◽  
Elementary Particles ◽  
Cosmological Models ◽  
Anthropic Principle ◽  
Coupling Constants ◽  
Inflationary Cosmology ◽  
Physical Parameters ◽  
Recent Advances ◽  
The Masses

Recent advances in string theory and inflationary cosmology have led to a surge of interest in the possible existence of an ensemble of cosmic regions, or "universes", among the members of which key physical parameters, such as the masses of elementary particles and the coupling constants, might assume different values. The observed values in our cosmic region are then attributed to an observer selection effect (the so-called anthropic principle). The assemblage of universes has been dubbed "the multiverse". In this paper we review the multiverse concept and the criticisms that have been advanced against it on both scientific and philosophical grounds.

Gaia spectroscopic view of the asteroid main belt and beyond

2021 ◽  
Author(s):  
Marco Delbo ◽  
Laurent Galluccio ◽  
Francesca De Angeli ◽  
Paolo Tanga ◽  
Alberto Cellino ◽  
...  
Keyword(s):  
Solar System ◽  
Preliminary Investigation ◽  
Planetary Science ◽  
Reflectance Spectra ◽  
Physical Parameters ◽  
The Novel ◽  
Main Belt ◽  
Compositional Gradient ◽  
Solar System Object ◽  
Science Community

<div class="">Asteroids reflectance spectra in the visible light will be one of the novel products of the Gaia Data Release 3 (DR3). These spectra are produced from Gaia observations obtained by means of the blue and red photometers — the so-called BP and RP, respectively. We will review the strategy adopted to produce asteroid reflectance spectra from BP-RP data, focusing on the choice of spectro-photometric calibrations computed taking into account solar system object astrometry and suitable lists of solar-analog stars.</div> <div class=""> </div> <div class="">Our preliminary investigation shows that we will be able to obtain reflectance spectra for asteroids as small as some km in the main belt, by exploiting the fact that each object has been observed multiple times by Gaia. We will show the capability of Gaia to probe the detailed compositional gradient of the main belt down to small sizes and to study correlations between spectral classes and other asteroid physical parameters, such as albedo and size.</div> <div class=""> </div> <div class="">Concerning the brightest asteroids, we expect to have substantial signal at wavelengths shorter than 450 nm, allowing Gaia to examine this region of the spectrum that has been poorly investigated by ground-based asteroid spectroscopic surveys. This region is characterised by the presence of a reflectance downturn that is diagnostic for the composition of classes of primitive asteroids, for instance those including the parent bodies of carbonaceous chondrites. These asteroids may have played an important role for the delivery of prebiotic compounds to Earth during the early phases of solar system' s history and, as such, are at the center of attention of the planetary science community. </div>

scholarly journals On the Distribution of Young Spectroscopic Binary Stars Over the Major Semiaxes of their Orbits

1982 ◽  
Vol 69 ◽  
pp. 129-131
Author(s):  
E.I. Popova ◽  
A.V. Tutukov ◽  
B.M. Shustov ◽  
L.R. Yungelson
Keyword(s):  
Binary Stars ◽  
Binary Systems ◽  
Spectroscopic Binaries ◽  
Close Binary ◽  
Physical Parameters ◽  
Origin And Evolution ◽  
Spectroscopic Binary ◽  
Visible Spectra ◽  
Major Semiaxes ◽  
The Masses

About 60% of stars of the disc population in our Galaxy are close binary systems (CBS). Half of the known CBS are spectroscopic binary stars (Kraitcheva et al., 1978).To know the distribution of a correlation between the masses of CBS components and semiaxes of their orbits is necessary for the investigation of the origin and evolution of CBS. For such statistical investigations, a catalogue of CBS was compiled at the Astronomical Council. The catalogue is based on the 6th Batten catalogue (Batten, 1967), its extensions (Pedoussant and Ginestet, 1971; Pedoussant and Carquillat, 1973) and data published up to the end of 1980 (Popova et al., 1981). Now it is recorded on magnetic tape and contains data on 1041 spectroscopic binaries; 333 of them are stars with two visible spectra. The latter are mostly systems prior to mass exchange and the distribution of physical parameters in these systems reflects the distribution and presumably conditions at the time of formation. Using some assumptions, we can obtain for spectroscopic binaries masses of the components M1 and M2 (or the ratio q = M1/M2) and semiaxes of their orbits. Masses of components with the known sin i were obtained by the usual technique; when sin i was not known, masses were estimated from the spectra. We shall discuss here the distribution of CBS in the M-a plane.

scholarly journals Mass discrepancy analysis for a select sample of Type II-Plateau supernovae

2019 ◽  
Vol 629 ◽  
pp. A124 ◽  
Author(s):  
Laureano Martinez ◽  
Melina C. Bersten
Keyword(s):  
Explosion Energy ◽  
Physical Parameters ◽  
Expansion Velocity ◽  
Type Ii ◽  
Hydrodynamic Models ◽  
Spectroscopic Monitoring ◽  
Select Group ◽  
Wide Range ◽  
The Masses ◽  
Hydrodynamical Modelling

The detailed study of supernovae (SNe) and their progenitors allows a better understanding of the evolution of massive stars and how these end their lives. Despite its importance, the range of physical parameters for the most common type of explosion, the type II supernovae (SNe II), is still unknown. In particular, previous studies of type II-Plateau supernovae (SNe II-P) showed a discrepancy between the progenitor masses inferred from hydrodynamic models and those determined from the analysis of direct detections in archival images. Our goal is to derive physical parameters (progenitor mass, radius, explosion energy and total mass of nickel) through hydrodynamical modelling of light curves and expansion velocity evolution for a select group of six SNe II-P (SN 2004A, SN 2004et, SN 2005cs, SN 2008bk, SN 2012aw, and SN 2012ec) that fulfilled the following three criteria: (1) enough photometric and spectroscopic monitoring is available to allow for a reliable hydrodynamical modelling; (2) a direct progenitor detection has been achieved; and (3) there exists confirmation of the progenitor identification via its disappearance in post-explosion images. We then compare the masses obtained by our hydrodynamic models with those obtained by direct detections of the progenitors to test the existence of such a discrepancy. As opposed to some previous works, we find good agreement between both methods. We obtain a wide range in the physical parameters for our SN sample. We infer presupernova masses between 10 and 23 M⊙, progenitor radii between 400 and 1250 R⊙, explosion energies between 0.2 and 1.4 foe, and 56Ni masses between 0.0015 and 0.085 M⊙. An analysis of possible correlations between different explosion parameters is presented. The clearest relation found is that between the mass and the explosion energy, in the sense that more-massive objects produce higher-energy explosions, in agreement with previous studies. Finally, we also compare our results with previous physical–observed parameter relations widely used in the literature. We find significant differences between both methods, which indicates that caution should be exercised when using these relations.

The Preliminary Results of Rock Physical Properties in Yudu-Ganxian Ore Concentration Area

2013 ◽  
Vol 813 ◽  
pp. 225-229
Author(s):  
Bin Zhao ◽  
Jian Guo Li ◽  
Shao Wei Sun ◽  
Xin Peng Zhou ◽  
Zhen Bin Wang ◽  
...  
Keyword(s):  
Physical Properties ◽  
Research Method ◽  
Three Dimensional ◽  
Physical Property ◽  
Physical Parameters ◽  
Distribution Characteristics ◽  
Actual Distribution ◽  
New Information ◽  
Metallogenic Prognosis ◽  
Rock Physical Property

As the lack of work on comprehensive rock physical properties in deep geophysical exploration in Yudu-Ganxian ore concentration area, this paper focuses in comprehensive and systematic study about the comprehensive rock physical properties in this area. Known from the rock (ore) actual distribution in this area, this paper presents the comprehensive rock physical properties research method of the area, which use varieties of techniques to collect specimens systematic, determine the physical parameters, and even study the distribution characteristics and variation law of rock (ore) integrated rock physical properties parameters. In this paper, the results can provide the new information about integrated rock physical property parameters for understanding and explaining the integrated geophysical anomaly, providing the basis for the future in Nanling to carry out deep geophysical three-dimensional exploration and deep metallogenic prognosis.

scholarly journals Orbital and physical parameters of eclipsing binaries from the ASAS catalogue – XI. CHIRON investigation of long-period binaries

2020 ◽  
Vol 500 (4) ◽  
pp. 4972-4988
Author(s):  
M Ratajczak ◽  
R K Pawłaszek ◽  
K G Hełminiak ◽  
M Konacki ◽  
P Sybilski ◽  
...  
Keyword(s):  
Cross Correlation ◽  
Eclipsing Binaries ◽  
Physical Parameters ◽  
Correlation Technique ◽  
Red Giants ◽  
Evolved Stars ◽  
V Band ◽  
The Masses ◽  
Cross Correlation Technique ◽  
Better Than

ABSTRACT We present the results of a spectroscopic campaign on eclipsing binaries with long orbital period (P = 20–75 d) carried out with the CHIRON spectrograph. Physical and orbital solutions for seven systems were derived from the V band, and I band ASAS, WASP, and TESS photometry, while radial velocities were calculated from high-quality optical spectra using a two-dimensional cross-correlation technique. The atmospheric parameters of the stars have been determined from the separated spectra. Most of our targets are composed of evolved stars (subgiants or red giants) but two systems show components in different phases of evolution and one possible merger. For four binaries, the masses and radii of the components were obtained with precision better than $3{{\ \rm per\ cent}}$. These objects provide very valuable information on stellar evolution.

scholarly journals Probing the Tides in Interacting Galaxy Pairs

1990 ◽  
Vol 124 ◽  
pp. 537-542
Author(s):  
Kirk D. Borne
Keyword(s):  
Gravitational Field ◽  
Binary System ◽  
Driving Forces ◽  
Elliptical Galaxies ◽  
Physical Parameters ◽  
Tidal Interactions ◽  
The Galaxy ◽  
Merger Rate ◽  
The Masses ◽  
Best Fit

AbstractDetailed spectroscopic and imaging observations of colliding elliptical galaxies have revealed unmistakable diagnostic signatures of the tidal interactions. It is possible to compare both the distorted luminosity distributions and the disturbed internal rotation profiles with numerical simulations in order to model the strength of the tidal gravitational field acting within a given pair of galaxies. Using the best-fit numerical model, one can then measure directly the mass of a specific interacting binary system. This technique applies to individual pairs and therefore complements the classical methods of measuring the masses of galaxy pairs in well-defined statistical samples. The “personalized” modeling of galaxy pairs also permits the derivation of each binary’s orbit, spatial orientation, and interaction timescale. Similarly, one can probe the tides in less-detailed observations of disturbed galaxies in order to estimate some of the physical parameters for larger samples of interacting galaxy pairs. These parameters are useful inputs to the more universal problems of (1) the galaxy merger rate, (2) the strength and duration of the driving forces behind tidally-stimulated phenomena (e.g., starbursts and maybe QSOs), and (3) the identification of long-lived signatures of interaction/merger events.

scholarly journals Thermal inertia of main belt asteroids smaller than 100km from IRAS data

2009 ◽  
Vol 57 (2) ◽  
pp. 259-265 ◽  
Author(s):  
Marco Delbo’ ◽  
Paolo Tanga
Keyword(s):  
Thermal Inertia ◽  
Main Belt

scholarly journals A Digital Video System for Observing and Recording Occultations

2015 ◽  
Vol 32 ◽  
Author(s):  
M. A. (Tony) Barry ◽  
Dave Gault ◽  
Hristo Pavlov ◽  
William Hanna ◽  
Alistair McEwan ◽  
...  
Keyword(s):  
Solar System ◽  
Dead Time ◽  
Low Cost ◽  
Low Noise ◽  
Recording System ◽  
Outer Solar System ◽  
Main Belt ◽  
Recording Equipment ◽  
The Past ◽  
Solar System Bodies

AbstractStellar occultations by asteroids and outer solar system bodies can offer ground based observers with modest telescopes and camera equipment the opportunity to probe the shape, size, atmosphere, and attendant moons or rings of these distant objects. The essential requirements of the camera and recording equipment are: good quantum efficiency and low noise; minimal dead time between images; good horological faithfulness of the image timestamps; robustness of the recording to unexpected failure; and low cost. We describe an occultation observing and recording system which attempts to fulfil these requirements and compare the system with other reported camera and recorder systems. Five systems have been built, deployed, and tested over the past three years, and we report on three representative occultation observations: one being a 9 ± 1.5 s occultation of the trans-Neptunian object 28978 Ixion (mv =15.2) at 3 seconds per frame; one being a 1.51 ± 0.017 s occultation of Deimos, the 12 km diameter satellite of Mars, at 30 frames per second; and one being a 11.04 ± 0.4 s occultation, recorded at 7.5 frames per second, of the main belt asteroid 361 Havnia, representing a low magnitude drop (Δmv = ~0.4) occultation.

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