Astronomy Reports最新文献_第10页

The Sun: Dark and Cold 太阳黑暗与寒冷

IF 1.1 4区物理与天体物理

Astronomy Reports Pub Date : 2024-02-25 DOI: 10.1134/S1063772923130036

S. A. Yazev

引用次数: 0

Activity Cycles of the Star FK Com FK Com 星的活动周期

IF 1.1 4区物理与天体物理

Astronomy Reports Pub Date : 2024-02-25 DOI: 10.1134/S1063772923120089

I. S. Savanov, S. A. Naroenkov, M. A. Nalivkin, E. S. Dmitrienko

{"title":"Activity Cycles of the Star FK Com","authors":"I. S. Savanov, S. A. Naroenkov, M. A. Nalivkin, E. S. Dmitrienko","doi":"10.1134/S1063772923120089","DOIUrl":"10.1134/S1063772923120089","url":null,"abstract":"We present the results of our photometric observations of the chromospherically active star FK Com (prototype of its group of stars) acquired during the recent 5 years (2018–2023) at the INASAN observatories in Zvenigorod and Simeiz and at the Russian–Cuban observatory in Habana (Republic of Cuba). In total, we obtained 9060 estimates of the star’s brightness in the V filter between 2018 and 2023. Our measurements, as well as data from the literature and from the Kamogata Wide-field Survey (KWS) archive, were combined into a unified set containing 17 653 measurements for a time interval about 57 years long. Based on the power spectrum derived from these data, we identified possible activity cycles ({{P}_{{{text{cycl}}}}}), estimated by us to be 2.4, 5.63, 8, 13.6, 30, and 49 years. The dominating ({{P}_{{{text{cycl}}}}}) is 5.63 years long. We show that the dominating cycle found by us from extensive data to be about 5.63 years (5.4–5.8 years from other sources in the literature) can also be noticed from the analysis of earlier studies. We compared our results on the activity cycles of FK Com to data on long-term variations of two other stars of the same type, HD 199178 (V1794 Cyg) and ET Dra. Data on ({{P}_{{{text{cycl}}}}}) of other chromospherically active stars (from the literature and from our measurements) were used to analyze the (log (1{text{/}}{{P}_{{{text{rot}}}}}){-} log ({{P}_{{{text{cycl}}}}}{text{/}}{{P}_{{{text{rot}}}}})) diagram. We make a conclusion on the compatibility of our determinations of activity cycles for stars of the FK Com type with data for RS CVn stars.","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"67 12","pages":"1394 - 1400"},"PeriodicalIF":1.1,"publicationDate":"2024-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140884832","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

Three Arguables: Point Particle Singularity, Asymmetry in EM and Quantum Waves, and the Left Out Restricted Lorentz Gauge from U(1) 三个争论点点粒子奇异性、电磁波和量子波中的不对称性，以及来自 U(1) 的遗漏限制洛伦兹量规

IF 1.1 4区物理与天体物理

Astronomy Reports Pub Date : 2024-02-25 DOI: 10.1134/S1063772923140196

Yousef Sobouti

{"title":"Three Arguables: Point Particle Singularity, Asymmetry in EM and Quantum Waves, and the Left Out Restricted Lorentz Gauge from U(1)","authors":"Yousef Sobouti","doi":"10.1134/S1063772923140196","DOIUrl":"10.1134/S1063772923140196","url":null,"abstract":"We address three issues: (1) The point particle assumption inherent to non-quantum physics is singular and entails divergent fields and integrals. (2) In quantum physics electromagnetism (EM) plays an asymmetric roll. It acts on quantum wave functions (QW) but QW does not react back. We suggest to promote the one-sided action of EM on QW into a mutual action-reaction status. This enables QW to share its non-singular feature with EM and to remove the Coulomb singularity. (3) Quantum mechanics is U(1) symmetric. QW multiplied by an arbitrary phase factor and EM written in7 the same Lorentz gauge, leave both EM and QW invariant. The minimal coupling of QW to the EM 4-vector potential, ({{A}_{mu }}), is a consequence of this arbitrary gauge. Symmetry under the restricted Lorentz gauge, is left out. We propose to enlarge U(1) to accommodate the restricted Lorentz gauge as well. This in turn invites in a coupling of QW to the derivatives of the vector potential, ({{partial }_{nu }}{{A}_{mu }}), in addition to the minimal coupling. We find that (i) electron acquires a distributed charge, reminiscent of the QED-renormalized charge distributions; (ii) because of its spin, electron acquires a self induced magnetic moment with the same g-factor as in QED but without relying on QED.","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"67 2 supplement","pages":"S134 - S139"},"PeriodicalIF":1.1,"publicationDate":"2024-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140884833","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

The Sun Made of Hot Gas 由高温气体组成的太阳

IF 1.1 4区物理与天体物理

Astronomy Reports Pub Date : 2024-02-25 DOI: 10.1134/S1063772923130048

S. A. Yazev

引用次数: 0

Simulations of Linear Polarization of Precessing AGN Jets at Parsec Scales 前冲 AGN 射流在等秒尺度上的线性极化模拟

IF 1.1 4区物理与天体物理

Astronomy Reports Pub Date : 2024-02-25 DOI: 10.1134/S1063772923120119

R. V. Todorov, E. V. Kravchenko, I. N. Pashchenko, A. B. Pushkarev

{"title":"Simulations of Linear Polarization of Precessing AGN Jets at Parsec Scales","authors":"R. V. Todorov, E. V. Kravchenko, I. N. Pashchenko, A. B. Pushkarev","doi":"10.1134/S1063772923120119","DOIUrl":"10.1134/S1063772923120119","url":null,"abstract":"The latest results of the most detailed analysis of multi-epoch polarization-sensitive observations of active galactic nuclei (AGN) jets at parsecs scales by very long baseline interferometry (VLBI) reveal several characteristic patterns of linear polarization distribution and its variability [1, 2]. Some of the observed profiles can be reproduced by a simple model of a jet threaded by a helical magnetic field. However, none of the models presented to date can explain the observed polarization profiles with an increase in its degree towards the edges of the jet, and accompanied by a “fountain” type electrical vector pattern and its high temporal variability in the center. Based on simulations of the VLBI observations of relativistic jets, we show here that the observed transverse linear polarization profiles can be naturally produced in a model of jets precessing on ten-years scales. In this scenario, due to the finite resolution of VLBI arrays, the initially strong polarization along the jet axis is blurred due to the superposition of regions whose polarization angle changes significantly when projected onto the sky plane. In our simulations, we qualitatively reproduce the distribution of the electric vector and its variability, though the polarization distribution images are characterized by a bright spine due to weak suppression of polarized emission, which is poorly consistent with observations of quasars. More effective depolarization can be obtained in models with the suppressed emission of the jet spine.","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"67 12","pages":"1275 - 1285"},"PeriodicalIF":1.1,"publicationDate":"2024-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140884918","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

Exploring Massive Neutron Stars Towards the Mass Gap: Constraining the High Density Nuclear Equation of State 探索大质量中子星的质量差距：约束高密度核状态方程

IF 1.1 4区物理与天体物理

Astronomy Reports Pub Date : 2024-02-25 DOI: 10.1134/S1063772923140214

Zenia Zuraiq, Banibrata Mukhopadhyay, Fridolin Weber

{"title":"Exploring Massive Neutron Stars Towards the Mass Gap: Constraining the High Density Nuclear Equation of State","authors":"Zenia Zuraiq, Banibrata Mukhopadhyay, Fridolin Weber","doi":"10.1134/S1063772923140214","DOIUrl":"10.1134/S1063772923140214","url":null,"abstract":"Due to the high-density nuclear matter equation of state (EOS) being as yet unknown, neutron stars (NSs) do not have a confirmed limiting “Chandrasekhar” type maximum mass. However, observations of NSs (PSR J1614-2230, PSR J0348+0432, PSR J0740+6620, PSR J0952–0607) indicate that the NS’s limiting mass, if there is any, could be well over (2{{M}_{ odot }}). On the other hand, there seems to be an observational mass gap (of around (2.5{-} 5{{M}_{ odot }})) between the lightest black hole and the heaviest NS. Therefore, the “massive NSs” are prime candidates to fill that gap. Several NS EOSs have been proposed using both microscopic and phenomenological approaches. In this project, we look at a class of phenomenological nuclear matter EOSs—relativistic mean field models—and see what kind of NS is formed from them. We compute the maximum mass supported by each model EOS to observe if the mass of the NS is indeed in the “massive” NS (( > {kern 1pt} 2{{M}_{ odot }})) regime. We also observe the effects of including exotic particles (hyperons, Δs) in the NS EOS and how that affects the NS mass. However, only by introducing the magnetic field, i.e. for magnetized anisotropic NSs, we find the mass exceeding (2.5{{M}_{ odot }}). Using tidal deformability constraints from gravitational wave observations, we place a further check on how physical the EOS and NSs are.","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"67 2 supplement","pages":"S199 - S206"},"PeriodicalIF":1.1,"publicationDate":"2024-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140885115","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

Solar Cycle Structure and Structure of Activity Cycles at Late-Type Stars 太阳周期结构和晚型恒星活动周期结构

IF 1.1 4区物理与天体物理

Astronomy Reports Pub Date : 2024-02-25 DOI: 10.1134/S1063772923120065

V. N. Obridko, D. D. Sokoloff, M. M. Katsova

引用次数: 0

Spectral Survey of the Star Formation Region DR21OH in the 4-mm Wavelength Range 4 毫米波长范围内恒星形成区 DR21OH 的光谱巡天

IF 1.1 4区物理与天体物理

Astronomy Reports Pub Date : 2024-02-25 DOI: 10.1134/S106377292312003X

S. V. Kalenskii, E. A. Mikheeva

{"title":"Spectral Survey of the Star Formation Region DR21OH in the 4-mm Wavelength Range","authors":"S. V. Kalenskii, E. A. Mikheeva","doi":"10.1134/S106377292312003X","DOIUrl":"10.1134/S106377292312003X","url":null,"abstract":"The results of a spectral survey of the region of massive star formation DR21OH in the 4-mm wavelength range are presented. Sixty-nine molecules and their isotopologues have been detected, ranging from simple diatomic or triatomic species such as SO, SiO and CCH, to complex organic molecules such as CH3OCHO or CH3OCH3. The obtained results qualitatively repeat the results of the survey of the same source at 3 mm. The inventories of molecules found at 3 and 4 mm overlap to a great extent. However, at 4 mm we found a number of species that have no allowed transitions in the 3-mm wavelength range, e.g., DCN, DNC, or SO+. The bulk of the molecules detected at 4 mm are those that are common for dense cores, e.g., HC3N or CH3CCH, but some of the detected species are typical for hot cores. The latter include complex organic molecules CH3OCHO, CH3CH2OH, CH3OCH3, etc. However, the detected emission of these molecules probably arises in a gas heated to 30 K only. Nine molecules, including complex species CH3C3N, CH3CH2CN, CH3COCH3, were found by spectral line stacking. This demonstrates the prospects of the method in the study of molecular clouds.","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"67 12","pages":"1303 - 1328"},"PeriodicalIF":1.1,"publicationDate":"2024-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139978671","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 High-Velocity Stars within 300 pc from the Sun according to Gaia DR3 根据盖亚DR3测定的距离太阳300 pc以内高速恒星的运动学特性

IF 1.1 4区物理与天体物理

Astronomy Reports Pub Date : 2024-02-25 DOI: 10.1134/S1063772923120120

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

引用次数: 0

Plausible Detection of Rotating Magnetized Neutron Stars by Their Continious Gravitational Waves 通过连续引力波探测旋转磁化中子星的可能性

IF 1.1 4区物理与天体物理

Astronomy Reports Pub Date : 2024-02-25 DOI: 10.1134/S1063772923140056

Mayusree Das, Banibrata Mukhopadhyay

{"title":"Plausible Detection of Rotating Magnetized Neutron Stars by Their Continious Gravitational Waves","authors":"Mayusree Das, Banibrata Mukhopadhyay","doi":"10.1134/S1063772923140056","DOIUrl":"10.1134/S1063772923140056","url":null,"abstract":"In the past decades, several neutron stars (NSs), particularly pulsars, with mass (M > 2{{M}_{ odot }}), have been observed. Hence, there is a generic question of the origin of massive compact objects. Here we explore the existence of massive, magnetized, rotating NSs by solving axisymmetric stationary stellar equilibria in general relativity using the Einstein equation solver for stellar structure XNS code. Such rotating NSs with magnetic field and rotation axes misaligned, hence with non-zero obliquity angle, can emit continuous gravitational waves (GW). We discuss the decay of the magnetic field due to Ohmic, Hall and Ambipolar diffusion, and the decay of angular velocity, and obliquity angle with time due to angular momentum extraction by GW and dipole radiation, which determine the timescales related to the GW emission. Further, in the Alfvén timescale, a differentially rotating, massive proto-NS rapidly settles into a uniformly rotating, less massive NS due to magnetic braking and viscosity. These explorations suggest that detecting massive NSs is challenging and sets a timescale for detection. We calculate the signal-to-noise ratio of GW emission, which confirms that any detector cannot detect them immediately, but detectable by Einstein Telescope and Cosmic Explorer over months of integration time, leading to direct detection of NSs.","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"67 2 supplement","pages":"S179 - S188"},"PeriodicalIF":1.1,"publicationDate":"2024-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140884759","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