Astronomy Reports最新文献

Approach of the NGC1977 Star Cluster to the TOI-2796 Host Star

IF 1.1 4区物理与天体物理

Astronomy Reports Pub Date : 2024-12-18 DOI: 10.1134/S1063772924700835

H. Y. Wakjira, S. H. Negu, D. A. Mosunova, M. D. Sizova, E. S. Postnikova, N. V. Chupina, A. M. Fateeva, A. M. Fateev, S. V. Vereshchagin

{"title":"Approach of the NGC1977 Star Cluster to the TOI-2796 Host Star","authors":"H. Y. Wakjira, S. H. Negu, D. A. Mosunova, M. D. Sizova, E. S. Postnikova, N. V. Chupina, A. M. Fateeva, A. M. Fateev, S. V. Vereshchagin","doi":"10.1134/S1063772924700835","DOIUrl":"10.1134/S1063772924700835","url":null,"abstract":"We searched for a rapprochement in space between a star cluster and an extrasolar planetary system in past epochs. We have found that a host star TOI-2796 is a candidate for such an encounter with the cluster NGC 1977. We estimated time and distance between the objects of such a rapprochement. These parameters allowed us to estimate the gravitational effect on the loss of comets from a hypothetical analogue of the Oort cloud of the TOI-2796. The place of the encounter in the sky is shown. This point can be considered to be the place of appearance of interstellar comets. We confirm and suggest that there is possibility of past and future stellar close encounters of stars with star clusters which can perturb the analogue of the Oort cloud’s stability and triggering cometary showers in the vicinity of giant planets. The orbital parameters for the sample are calculated using the galpy package. The MWPotential14 gravitational potential is used, composed of a power law, exponentially cut-off bulge, Miyamoto–Nagai potential disc, and Navarro–Frenk–White dark matter halo. Time calculations were carried out within the age limits of the objects considered. The color-absolute magnitude diagram and the isochron system were used to calculate the age of the cluster. By extending the tracks of the cluster and stars’ motion in past epochs (~5.4 Myr), the time of the maximum approach (≈30 pc) of the TOI-2796 star, hosting a planetary system, with NGC 1977 has been found. As a result of our research, we derived that the host star’s approach with the cluster might entail effects related with the cluster’s gravitational pull on the nuclei of comets located in the outer border of the planetary system’s Oort cloud. The impact of approach on Oort cloud comets has been estimated.","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"68 10","pages":"967 - 977"},"PeriodicalIF":1.1,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142844778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Simulation of the Free Fall of a Gas Stream on a Protoplanetary Disk 模拟原行星盘上气体流的自由下落

IF 1.1 4区物理与天体物理

Astronomy Reports Pub Date : 2024-12-18 DOI: 10.1134/S1063772924700859

V. V. Grigoryev, T. V. Demidova

{"title":"Simulation of the Free Fall of a Gas Stream on a Protoplanetary Disk","authors":"V. V. Grigoryev, T. V. Demidova","doi":"10.1134/S1063772924700859","DOIUrl":"10.1134/S1063772924700859","url":null,"abstract":"The problem of the formation of exoplanets in inclined orbits relative to the equatorial plane of the parent star or the main plane of the protoplanetary disk can be solved by introducing a smaller inclined disk. However, the question of the nature of such an internal disk remains open. In the paper, we successfully tested the hypothesis about the formation of an inclined inner disk in a protoplanetary disk near a T Tau type star as a result of a gas stream falling on it. To test the hypothesis, three-dimensional gas-dynamic calculations were performed taking into account viscosity and thermal conductivity using the PLUTO package. In the course of the analysis of calculations, it was shown that a single intersection of the matter stream with the plane of the disk cannot ensure the formation of an inclined disk near the star, while a double intersection can. In addition, in the case of a retrograde fall of matter, the angle of inclination of the resulting inner disk is significantly greater. An analysis of the observational manifestations of this event was also carried out: the potential change in the brightness of the star, the distribution of optical thickness in angles, the evolution of the accretion rate. It is shown that the decrease in brightness can reach up to ({{5}^{m}}), taking into account scattered light, and such a decrease in brightness will last several decades. In addition, a sharp increase in the accretion rate by two orders of magnitude could potentially trigger an FU Ori-like outburst.","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"68 10","pages":"949 - 966"},"PeriodicalIF":1.1,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142844989","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Should We Expect Further Acceleration of the Earth’s Rotation in the Coming Years? 我们是否应该期待地球自转在未来几年进一步加速？

IF 1.1 4区物理与天体物理

Astronomy Reports Pub Date : 2024-12-18 DOI: 10.1134/S1063772924700884

Z. M. Malkin

引用次数: 0

Erratum to: On the Generalized Kepler Problem under the Effect of Outer Third-Body Perturbation 勘误：论外部第三体扰动作用下的广义开普勒问题

IF 1.1 4区物理与天体物理

Astronomy Reports Pub Date : 2024-12-18 DOI: 10.1134/S1063772924100019

M. R. S. Suzuki

引用次数: 0

New Look at the Structure of the Nearest Circumstellar Environment of the Weak-Line T Tauri Star V718 Per 弱线金牛座恒星 V718 Per 的最近恒星环环境结构新观察

IF 1.1 4区物理与天体物理

Astronomy Reports Pub Date : 2024-12-18 DOI: 10.1134/S1063772924700860

V. P. Grinin, B. S. Safonov, N. V. Efimova, O. Yu. Barsunova, I. A. Strachov, G. A. Borman, S. Yu. Shugarov

{"title":"New Look at the Structure of the Nearest Circumstellar Environment of the Weak-Line T Tauri Star V718 Per","authors":"V. P. Grinin, B. S. Safonov, N. V. Efimova, O. Yu. Barsunova, I. A. Strachov, G. A. Borman, S. Yu. Shugarov","doi":"10.1134/S1063772924700860","DOIUrl":"10.1134/S1063772924700860","url":null,"abstract":"In this paper, we have analyzed the properties of the photometric and spectral variability of young star V718 Per, a member of the cluster IC 348, in terms of its possible binarity. The most realistic is the model where the main component of the V718 Per A system—with an effective temperature of 5200 K—is periodically shielded by two extended dust structures consisting of large particles and moving around the star in resonance with two planets. Their orbital periods are 4.7 years and 213 days. Their ratio with high accuracy is equal to 1 : 8, and the ratio of the large semi-axes is 1 : 4. The masses of the planets have not exceeded (6 ,{{M}_{{{text{Jup}}}}}). At the moments of total eclipses V718 Per A, the radiation of the system has been dominated by a colder component with an effective temperature of (4150 pm 100) K, which has explained the reddening of the star observed in the brightness minima, as well as its spectral changes during brightness weakening. Speckle interferometric observations performed using the 2.5-m telescope of the Sternberg Astronomical Institute have made it possible to estimate the upper limit of the angular distance between the components of the system: ≤0.1('' ), which is equivalent to a projection distance of ≤30 AU. The unique feature of this system has been that the planes of the planetary orbits practically coincide with the line of sight. Such an orientation of the system has been most favorable for measuring fluctuations in the radial velocity of a star caused by the orbital motion of planets, as well as for observing planetary transits along the disk of the main component of the system.","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"68 10","pages":"995 - 1002"},"PeriodicalIF":1.1,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142844779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

New Formula for the Angular Velocity of Rotation of Liquid Equilibrium Figures

IF 1.1 4区物理与天体物理

Astronomy Reports Pub Date : 2024-12-18 DOI: 10.1134/S1063772924700872

B. P. Kondratyev

引用次数: 0

Destruction of Open Star Clusters and the Radius–Mass Relationship 疏散星团的毁灭与半径-质量关系

IF 1.1 4区物理与天体物理

Astronomy Reports Pub Date : 2024-12-18 DOI: 10.1134/S1063772924700896

A. V. Tutukov, S. V. Vereshchagin, N. V. Chupina

引用次数: 0

Spot Activity of the Dwarf Star V772 Her 矮星 V772 Her 的光斑活动

IF 1.1 4区物理与天体物理

Astronomy Reports Pub Date : 2024-12-18 DOI: 10.1134/S1063772924700847

I. Yu. Alekseev, A. V. Kozhevnikova, V. P. Kozhevnikov

引用次数: 0

Study of Maser Emission in 18 cm Lines in the Star Formation Region G 109.871+2.114 (Cep A)

IF 1.1 4区物理与天体物理

Astronomy Reports Pub Date : 2024-12-08 DOI: 10.1134/S106377292470080X

E. E. Lekht, N. T. Ashimbaeva, V. V. Krasnov, V. R. Shutenkov

{"title":"Study of Maser Emission in 18 cm Lines in the Star Formation Region G 109.871+2.114 (Cep A)","authors":"E. E. Lekht, N. T. Ashimbaeva, V. V. Krasnov, V. R. Shutenkov","doi":"10.1134/S106377292470080X","DOIUrl":"10.1134/S106377292470080X","url":null,"abstract":"The results of the study of the star formation region G 109.871+2.114 (Cep A) in OH lines at 18 cm are presented. Polarization observations (monitoring) were performed with a large Nançay radio telescope (France) in 2007–2024. OH maser emission is highly variable. The structure of the spectrum and the flux density of the individual spectral features are changing. However, the radial velocities of most features changed slightly. Short-term emission flares in individual features were observed. Many features have strong circular polarization, reaching 100%, but have weak linear polarization. A new features at –15.53 km/s and a short-term part at 1.58 km/s with high circular and low linear polarizations were detected in the 1667 MHz line. The spectral features of our monitoring were spatially identified with the maser spots on the Cohen, Argon, and Fish maps. The magnitude of the monotonic decrease in splitting, and, consequently, the longitudinal magnetic field of three Zeeman pairs (–16.2L/–14.25R and –6.94L/–0.82R km/s in the 1665 MHz line and –15.76L/–14.2R in the 1667 MHz line). For the –13.95L/–11.60R pair, no splitting change was detected in the 1665 MHz line. Broadband absorption and emission are observed in the satellite lines of 1612 and 1720 MHz, respectively. A Zeeman pair was also detected in the 1720 MHz line. The position angle (chi ) is calculated for linearly polarized emission of most spectral features in both main lines at 1665 and 1667 MHz. It is shown that the magnetic field in the H II regions is oriented either along the external magnetic field or along the radio jets.","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"68 9","pages":"906 - 924"},"PeriodicalIF":1.1,"publicationDate":"2024-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142790389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Kinematics of Fainst Stars of the Sco-Cen Association According to Gaia Catalog

IF 1.1 4区物理与天体物理

Astronomy Reports Pub Date : 2024-12-08 DOI: 10.1134/S106377292470077X

V. V. Bobylev, A. T. Bajkova

引用次数: 0