Astronomy Reports
Astronomy Reports is a peer-reviewed journal that publishes original papers on astronomical topics, including theoretical and observational astrophysics, physics of the Sun, planetary astrophysics, radio astronomy, stellar astronomy, celestial mechanics, and astronomy methods and instrumentation. Previously focused on translation, the journal now has the aim to become an international publication and accepts manuscripts originally submitted in English from all countries, along with translated works.
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The journal follows the Springer Nature Peer Review Policy, Process and Guidance, Springer Nature Journal Editors' Code of Conduct, and COPE's Ethical Guidelines for Peer-reviewers.
Approximately 5% of the manuscripts are rejected without review based on formal criteria as they do not comply with the submission guidelines. Each manuscript is assigned to at least one peer reviewer. The journal follows a single-blind reviewing procedure. The period from submission to the first decision is up to 37 days. The approximate rejection rate is 15%. The final decision on the acceptance of a manuscript for publication is made by the Meeting of the Members of the Editorial Board.
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Vol 63, No 12 (2019)
- Year: 2019
- Articles: 12
- URL: https://journals.rcsi.science/1063-7729/issue/view/12141
Article
Angular Momentum Distribution in Galaxies and Inner Haloes Profile
Abstract
In this paper, we extend the Romanowsky and Fall (2012) results concerning the stellar angular momentum to the mass range 103 ≲ M*/M⊙ ≲ 1012, and using this result, we calculate the inner slope, α of haloes density profiles in terms of Vrot, by using a previous model of Del Popolo, taking into account the interactions between dark matter and baryons through dynamical friction. Using the McConnachie sample, and that of Romanowsky and Fall, based only on observations, we show that in the quoted sample the rotationally supported galaxies, and the pressure supported ones are divided by a break atM* ≃ 107.8M⊙. Then we show that the slope α flattens monotonically, from α ≃ − 1 to α ≃ 0. The flattening is due to the increase of specific angular momentum moving fromMilkyWay-type galaxies to disk dwarf galaxies. Since at M* < 107.8M⊙, non-rotational supported galaxies start to dominate, the inner slope steepens again. The paper also extends the main result of Del Popolo (2016) to morphologies different from spheroids, and disks, taking into account the different morphologies delimited by the quoted ones. We finally compared our results with Di Cintio SPH simulations. The two models differ mainly at stellar masses smaller than M* ≲ 107.8M⊙. In our model the inner slope is flatter than in simulations. This imply that even finding a cored, α ≃ 0.4, profile in dSphs with masses slightly smaller than ≃106M⊙ will not imply necessarily a problem for the ΛCDM mode, as predicted by some simulations. To check which one of the two model was better describing data in this region, we used the LITTLE THINGS data, and compared the two models through a χ2, finding that our model gives a better description of the data.
971-989
Reheating Temperature from D-Term Cosmological Inflation Braneworld
Abstract
The D-term inflation in supergravity, in the braneworld Randall Sundrum II (RSII) context, has been proposed to solve some problems related to the four-dimensional inflation model. That scenario is based on a modification of the Friedmann equation by the addition of the fifth dimension, which corresponds to an energy, called brane tension λ. Therefore, we propose the investigation of the brane effect on the reheating epoch. In this context, we have analyzed the process of reheating and focused on the variation of the temperature value Tre. We found that it depends on all parameters, and the value found is in the range Tre ∼ (7.5 × 108−8 × 1010) GeV, which is consistent with the thermal leptogenesis (Tre ≥ 108 GeV).
990-997
Chemical Composition of Globular Clusters of Milky Way Subsystems from Gaia DR2 Data
Abstract
Results of a study of the kinematic and chemical properties of globular clusters of the Milky Way based on data from the Gaia DR2 catalog and meaurements with the Hubble Space Telescope are presented. A new method for dividing globular clusters into Galatic subsystems based on the elements of their Galactic orbits is proposed. Samples of globular clusters belonging to the bar/bulge, thick disk, and halo of the Milky Way are obtained. The mean metallicities of the globular clusters in various subsystems are calculated. The mean metallicities of globular clusters of the thick disk and halo display statistically significant differences. At the same time, no statistically significant differences are present between the mean metallicities of halo globular clusters moving in the direction of rotation of the Galactic disk and those moving in the retrograde direction. This argues against the suggestion that retrograde and prograde globular clusters have different origins.
998-1009
Hyperfine Splitting in the VALD Database of Spectral-line Parameters
Abstract
The Vienna Atomic Line Database (VALD) has been supplemented with new data and new functionality—the possibility of taking into account the effect of hyperfine splitting (HFS) of atomic levels in the analysis of line profiles. This has been done through the creation of an ancillary SQL database with the HFS constants for atomic levels of 58 isotopes of 30 neutral and singly-ionized atoms. The completeness of the collected data and new opportunities for studies of stars of various spectral types is analyzed. The database enables analysis of splitting of up to 60% of lines with measurable effects in the ultraviolet (λ ≳ 1000 Å ), and up to 100% of such lines in the optical and infrared ranges (λ ≲ 25 000 Å ) for A–M stars. In the spectra of hot O–B stars, it is necessary to use laboratory measurements for atoms in the second and higher stages of ionization.
1010-1021
Evolution of the H2O Maser Emission in the Star-Forming Region S252A
Abstract
Results of observations of the star-forming region S252A in the 1.35-cm H2O and 18-cm OH lines obtained using the 22-m Pushchino (Russia) and Nancay (France) radio telescopes are presented. A catalog of H2O maser spectra for 1995-2019 is presented. The variability of the integrated flux has two components: a cyclic component with a time interval between cycles ~30-35 yrs and a short-period component with a mean period of about 2.6 yrs. This may reflect non-stationary formation of a protostar. It is shown that the medium where the H2O maser emission and thermal OH emission are generated is strongly fragmented, and contains small-scale turbulent motions comparable to the thermal motions of the matter. The observed drift and jumps in the radial velocity of the H2O emission features could be a consequence of complex, non-uniform structure of the maser condensations.
1022-1034
Results of Many-year Photometry of the Herbig Ae Star AB Aur in the Near Infrared
Abstract
The results of many-year infrared observations of the Herbig AeBe star AB Aur at 1-5 μm (JHKLM bands) are presented. The duration of the photometric series, together with observations published earlier, is about 18 years. The observations demonstrate that, in contrast to the optical, the star is quite active in the studied infrared range. The variability amplitude increases with wavelength, reaching ΔM = 0.72m. Modeling shows that both the amount of IR radiation from the inner part of the disk and its temperature increase when the star becomes brighter. A periodogram analysis demonstrates that variations of the IR flux from AB Aur display significant evidence for periodic changes, whose stability is uncertain. This behavior is most probably associated with transient quasi-oscillations related to instability processes in the inner disk. The estimated correlation timescale, τ = 130 ± 40d, can be considered as an approximate characteristic of the duration of such processes. The analysis results provide no certain grounds to believe that the inner disk contains any massive objects in permanent orbits, such as protoplanets. The existing trend in the variations of the IR flux, most clearly expressed in the KLM bands, provides evidence for the presence of large-scale perturbations in the disk. Conditions that could bring about a cyclic character in the accretion of gas from the circumstellar disk onto the young star are briefly discussed.
1035-1044
Periodic Accretion in the T Tauri Binary UZ Tau E
Abstract
Results of three-dimensional numerical simulations of the gas dynamics of the envelope of the young T Tauri binary star UZ Tau E are considered. The flow structure in the circumstellar envelope of the system is analyzed. It is shown that a regime with the impulsive accretion of matter from the circumstellar disk is realized in the binary system, in which there is a periodic transfer of matter to the accretion disk of the primary component through the accretion disk of the secondary.
1045-1055
The MASTER Global Robotic Telescope Network: Observations of Asteroid NEA 2015 TB145
Abstract
The results of white-light photometry for a uniquely long series of data (13.5 hours of observations, 1124 measurements) for the Near-Earth Asteroid (NEA) 2015 TB145 are presented. These data were obtained with the MASTER-Amur and MASTER-Tavrida wide-field robotic telescopes of the Mobile Astronomical System of Telescope-Robots (MASTER) global network of Lomonosov Moscow State University, located in the Crimea and in Blagoveshchensk. The object moved by more than 120° during the observations. The asteroid passed the point of closest approach to the Earth, i.e., observations were carried during both the asteroid's approach and recession. Thus, due to the geometry of the passage, this series of observations contains information about the asteroid viewed at different angles, and is very suitable for precisely determining the shape of the object. Mathematical modeling of the light curve and astrometric positions (with the Asteroids3D code) was carried out, and the probable shape of the asteroid (conical) and the rotation period of 5.9 hours were obtained, as well as the orientation of the rotation axis in ecliptic coordinates: longitude λ = 53°, latitude β = −20°. The derived period coincides with twice the period of 2.9 hours obtained by other observers published earlier, within the uncertainties.
1056-1068
A New Classification and Index Calibration of Lunar Impact Craters for Digital Terrain Analysis
Abstract
Impact craters are the most typical geomorphological structural unit on the lunar surface. The craters record the characteristics of the Moon’s spherical appearance and the history of its geological evolution, so they form a basis for studies on the lunar surface. At present, mainstream classification is mainly qualitative and focuses more on the morphological characteristics of individual craters rather than the characteristics of different combinations of structures between craters. This is not conducive to designing modern crater detection algorithms. In this study, 100 m resolution digital elevation model (DEM) data obtained with the laser height measurement method were used to analyze the crater morphology, and 1407 impact craters of different types were selected from the lunar surface. Then, the craters were divided into six types based on spatial combination structures between impact craters, degradation of the crater boundaries, and complexity of the crater cross-section: dispersed craters, connected craters, contained craters, dispersed craters with rim degradation, connected craters with rim degradation, and contained craters with rim degradation. Finally, four description indicators were selected to quantitatively describe craters and analyze the differences in crater morphology: the volume to represent the scale, the slope of the crater wall to represent the evolution degree, the posture ratio to represent the geometric characteristics, and the circularity to represent the complexity. The results demonstrated that the proposed classification can be used to effectively design an automatic detection algorithm and accurately depicts the basic morphological features of the craters.
1069-1079
Non-Linear Moving Barrier and the Ordinary and Conditional Mass Function
Abstract
We study the problem of the determination of a high precision cosmological mass function, which is of fundamental importance in several problems of astrophysics, like the building up of an halo model. The determination of a mass function through numerical simulation is time demanding, and restrict to particular cosmological parameters. Analytical methods, allow to determine high precision mass functions, without the limitations of the simulations. We improve on previous analytical models, reaching high level of precision. In particular, we improve the scheme of Del Popolo presented in older and more recent papers, based on the excursion set approach. We further improve the mass function with respect to the quoted papers, using an higher order first crossing distribution, and an improved barrier with respect previous papers. As a result, we can obtain a mass function with a precision of 1%, in the mass range ≃ (109−1015) h−1M☉, and in the redshift range 0 < z s< 10. The paper also shows how the use of the quoted improved first-crossing distribution, improves the agreement between the conditional mass function, and simulations.
1080-1089
The Simulation of Orbit Decay of Double Neutron Star System PSR J1906+0746 by the Gravitational Wave Radiation
Abstract
With the discovery of the double neutron star (DNS) merger event GW170817 by LIGO, DNS systems have become one of the important candidates for gravitational wave (GW) observation. There are 19 DNS systems that have been discovered, and PSR J1906+0746 is the youngest DNS system with the age of about 0.1 Myrs. We simulate its orbital decay over its entire life by the GW radiation from the initial stage to the coalescence. For the DNS PSR J1906+0746, we obtain its initial orbital period of 3.99 hrs (3.98 hrs at present) with the nearly circular orbit, and the merger age of 3.18 × 108 yr. At the last minute of coalescence, corresponding to the orbital radius change from 335 to 30 km, we present the GW frequency to be 30 and 1122 Hz, respectively. As a comparison, with the GW frequency from 45 to 450 Hz, the orbital radii of the source GW170817 correspond to 163 and 57 km, respectively.
1090-1094
Erratum
1095-1095