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Dark Matter (S)pins the Planet

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arXiv 2025年

作者： Shi, Haihao Zhou, Junda Huang, Zhenyang Lü, Guoliang Chen, Xuefei Xinjiang Astronomical Observatory Chinese Academy of Sciences Urumqi830011 China College of Astronomy and Space Science University of Chinese Academy of Sciences Beijing101408 China Yunnan Observatories Chinese Academy of Sciences Kunming650216 China School of Physical Science and Technology Xinjiang University Urumqi830046 China Key Laboratory for Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China

Dark matter heating in planets has been proposed as a potential probe for dark matter detection. Assuming near-equilibrium, we find that dark matter energy input raises planetary temperature and accelerates rotation. The energy distribution depends on planetary properties and external input, suggesting that previous studies have overestimated its heating effect. When dark matter density is high, planetary rotation stabilizes earlier and is primarily governed by dark matter. For Earth, our model predicts a 0.015 K temperature increase and a 10−8 rad/s angular velocity increase over 100 years. Copyright © 2025, The Authors. All rights reserved.

关键词： Dark energy

One model to rule them all: magnetic braking from CVs to low-mass stars

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arXiv 2024年

作者： Sarkar, Arnab Ge, Hongwei Yungelson, Lev Tout, Christopher A. Institute of Astronomy University of Cambridge The Observatories Madingley Road CambridgeCB3 OHA United Kingdom Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for Structure and Evolution of Celestial Objects CAS Kunming650216 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China Institute of Astronomy of the Russian Academy of Sciences 48 Pyatnitskaya Str. Moscow119017 Russia

We present the results of the study of the secular evolution of donor stars in cataclysmic variables (CVs) and AM Canum Venaticorum (AM CVn) stars with our double dynamo (DD) formalism of angular momentum loss (AML) by magnetic braking (MB). In our DD model, MB is driven by an interplay between two ∝ − Ω dynamos, one in the convective envelope and the other at the boundary of the radiative core and the convective envelope. We show that (1) our MB model reproduces the period gap (2 Porb/ hr 3) and the period minimum spike (Porb ≈ 80 min) in the distribution of non-magnetic CVs, (2) evolved CVs, where the donor star commences Roche lobe overflow (RLOF) close to or just beyond the end of the main-sequence, populate the region in and beyond the period gap, and are more likely to be detected at Porb ≥ 5.5 hr. This likely contaminates the mass-radius fit of long-period CV donors. We show that (3) some of the evolved CVs become AM CVn stars with 10 Porb/ min 65. Their evolution, driven by AMLMB and AML by gravitational radiation (GR, AMLGR), leaves them extremely H-exhausted to the point of being indistinguishable from AM CVn systems formed via the He-star and the White Dwarf (WD) channels in terms of the absence of H in their spectra. We further show that (4) owing to the presence of a significant radiative region, intermediate-mass giants/sub-giants, which are progenitors of AM CVn stars formed through the He-star channel, may undergo common envelope evolution that does not behave classically, (5) several AM CVn systems with extremely bloated donors, such as Gaia14aae, ZTFJ1637+49 and SRGeJ045359.9+622444 do not match any modelled trajectories if these systems are modelled only with AMLGR without incorporating AMLMB, (6) the uncertainties in MB estimates greatly affect modelling results. This, in turn, affects our efforts to distinguish between different AM CVn formation channels and their relative importance. Finally, we find that (7) a similar MB prescription also expl

关键词： Uncertainty analysis

Exploring variation of double-peak broad-line profile in strongly variable AGNs

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arXiv 2024年

作者： Wu, Jiancheng Wu, Qingwen Lu, Kaixing Cao, Xinwu Lei, Xiangli Wang, Mengye Fan, Xiao Department of Astronomy School of Physics Huazhong University of Science and Technology Luoyu Road 1037 Wuhan China Yunnan Observatories Chinese Academy of Sciences Kunming650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China Institute for Astronomy School of Physics Zhejiang University 866 Yuhangtang Road Hangzhou310058 China

The geometry and kinematics of the broad-line region (BLR) in AGNs are still unclear, which is crucial for studying the physics and evolution of supermassive black holes (SMBHs) and AGNs. The broad-line profile provides valuable information on BLR geometry and kinematics. In this work, we explore the evolution of line profiles in variable AGNs based on the BLR model of Czerny & Hryniewicz, where the BLR is driven by the radiation pressure acting on dust at the surface layers of the accretion disk. The line profiles in the low-Eddington-ratio regime show a double-peak profile, which will become a single peak at high Eddington ratios. The high metallicity of Z 5Zo is required to reproduce the observational anti-correlation between the peak separation of broad lines and the Eddington ratio for a sample of AGNs. For the broad lines in variable AGNs, it will take several years to several decades to change their line profile if the disk luminosity suffers strong variation in a much shorter timescale. More monitoring of the broad line and continuum in strongly variable AGNs can shed special light on BLR physics. © 2024, CC BY.

关键词： Kinematics

On the rotation properties of a post-explosion helium-star companion in Type Iax supernovae

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arXiv 2022年

作者： Zeng, Yaotian Liu, Zheng-Wei Meng, Xiangcun Han, Zhanwen Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects CAS Kunming650216 China University of Chinese Academy of Science Beijing100012 China Center for Astronomical Mega-Science CAS Beijing100012 China

Recent studies have suggested that type Iax supernovae (SNe Iax) are likely to result from a weak deflagration explosion of a Chandrasekhar-mass white dwarf in a binary system with a helium (He)-star companion. Assuming that most SNe Iax are produced from this scenario, in this work we extend our previous work on the three-dimensional hydrodynamical simulation of ejecta-companion interaction by taking the orbital and spin velocities of the progenitor system into account. We then follow the post-impact evolution of a surviving He-star companion by using the one-dimensional stellar evolution code MESA. We aim to investigate the post-explosion rotation properties of a He-star companion in SNe Iax. We find that the He-star companion spins down after the impact due to the angular-momentum loss and expansion caused by the mass-stripping and shock heating during the interaction. This leads to the situation where the surface rotational speed of the surviving companion can drop to one-third of its pre-explosion value when it expands to a maximum radius a few years after the impact. Subsequently, the star shrinks and spins up again once the deposited energy is released. This spin-switching feature of the surviving He-star companions of SNe Iax may be useful for the identification of such objects in future observations. Copyright © 2022, The Authors. All rights reserved.

关键词： Helium

Two categories of UV-upturn galaxies revealed by semi-analytic models

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arXiv 2025年

作者： Jiang, Zhen Li, Cheng Zhang, Fenghui Zhou, Shuang Department of Astronomy Tsinghua University Beijing100084 China National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China INAF–Osservatorio Astronomico di Brera via Brera 28 Milano20159 Italy

UV-upturn galaxies are characterized by unusually excessive flux in the far-ultraviolet (FUV) band, observed in some elliptical galaxies and the bulges of disk galaxies. We examine UV-upturn galaxies within the semi-analytic model gabe, which embeds the formation of extreme horizontal branch (EHB) stars—proposed as key candidates responsible for the UV-upturn phenomenon. We have analyzed all related physical processes, including stellar evolution, initial mass functions (IMFs), dust attenuation, galaxy age, metallicity, and binary fractions, in an effort to determine which processes play significant roles. Our findings reveal two categories of UV-upturn galaxies in the semi-analytic model, each with distinct formation channels: old metal-rich quenched elliptical galaxies, which are intrinsic UV-upturn galaxies induced by EHB stars within their old stellar populations, and dusty star-forming galaxies, which are relatively young and may also be photometrically identified as UV-upturn galaxies when accounting for dust attenuation. Dust attenuation contributes to 20% − 60% of the UV-upturn galaxies, depending on the specific dust attenuation models adopted. With the binary star formation model of EHB stars, both of these formation channels exhibit strong preferences for high stellar metallicity. The high-mass end slope of the IMFs is found to have a marginal effect, indicating that a universal IMF is adequate for studying the UV-upturn phenomenon. Copyright © 2025, The Authors. All rights reserved.

关键词： Dust

Black Hole Ultracompact X-Ray Binaries as Galactic Low-frequency Gravitational Wave Sources: the He Star Channel

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arXiv 2023年

作者： Qin, Ke Xu, Kun Liu, Dong-Dong Jiang, Long Wang, Bo Chen, Wen-Cong School of Science Qingdao University of Technology Qingdao266525 China School of Physics Zhengzhou University Zhengzhou450001 China Key Laboratory for the Structure and Evolution of Celestial Objects Yunnan Observatories Chinese Academy of Sciences Kunming650216 China School of Physics and Electrical Information Shangqiu Normal University Shangqiu476000 China

Black hole (BH) ultracompact X-ray binaries (UCXBs) are potential Galactic low-frequency gravitational wave (GW) sources. As an alternative channel, BH UCXBs can evolve from BH+He star binaries. In this work, we perform a detailed stellar evolution model for the formation and evolution of BH UCXBs evolving from the He star channel to diagnose their detectability as low-frequency GW sources. Our calculations found that some nascent BH+He star binaries after the common-envelope (CE) phase could evolve into UCXB-LISA sources with a maximum GW frequency of ∼ 5 mHz, which can be detected in a distance of 10 kpc (or 100 kpc). Once BH+He star systems become UCXBs through mass transfer, they would emit X-ray luminosities of ∼ 1038 erg s−1, making them ideal multimessenger objects. If the initial He-star masses are ≥ 0.7M☉, those systems are likely to experience two Roche lobe overflows, and the X-ray luminosity can reach a maximum of 3.5 × 1039 erg s−1 in the second mass-transfer stage. The initial He-star masses and initial orbital periods of progenitors of Galactic BH UCXB-LISA sources are in the range of 0.32-2.9 M☉ and 0.02-0.19 days, respectively. Nearly all BH+He star binaries in the above parameter space can evolve into GW sources whose chirp masses can be accurately measured. Employing a population synthesis simulation, we predict the birthrate and detection number of Galactic BH UCXB-LISA source evolving from the He star channel are R = 2.2 × 10−6 yr−1 and 33 for an optimistic CE parameter, respectively. © 2023, CC0.

关键词： Gravity waves

Absolute physical parameters of three poorly studied detached eclipsing binaries

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Research in Astronomy and Astrophysics 2021年第1期21卷 220-228页

作者： Dao-Ye Yang Li-Fang Li Quan-Wang Han Yunnan Observatories Chinese Academy of SciencesKunming 650216China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China University of Chinese Academy of Sciences Beijing 100049China Center for Astronomical Mega-Science Chinese Academy of SciencesBeijing 100012China Key Lab of Optical Astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 10101China School of Physics and Electronics Qiannan Normal University for NationalitiesDuyun 558000China

The photometric and spectroscopic data for three double-lined detached eclipsing binaries were collected from the photometric and spectral *** light and radial velocity curves of each binary system were simultaneously analyzed using Wilson-Devinney(WD)code,and the absolute physical and orbital parameters of these binaries were *** masses of both components of ASASSN-V J063123.82+192341.9 were found to be M1=1.088±0.016 and M20.883±0.016 M⊙;those of ASAS J011416+0426.4 were determined to be M1=0.934±0.046 and M2=0.754±0.043 M⊙;and those of MW Aur were derived to be M1=2.052±0.196 and M21.939±0.193 M⊙.Finally,the evolutionary status of these detached binaries was discussed based on their absolute parameters and the theoretical stellar models.

关键词： stars:binaries:eclipsing stars:fundamental parameters stars:evolution stars:individual:ASASSN-V J063123.82+192341.9,ASAS J011416+0426.4 and MW Aur

Relation between spectral indices and binary fractions in GCs

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arXiv 2023年

作者： Zhang, Fenghui Li, L. Han, Z. Gong, X. Yunnan Observatories Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China University of Chinese Academy of Sciences Beijing100049 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China

Context. We study the relation between the known binary fraction and spectral absorption feature index to judge whether (and potentially which) spectral absorption feature indices are suitable for determining the binary fraction. Aims. The determination of the binary fraction is important in studies of binary star formation, evolutionary population synthesis models, and other works. The number of binary stars is difficult to determine for nearly all stellar systems because the individual stars are need to be resolved photometrically or spectroscopically. By comparison, their integrated spectra or spectral absorption feature indices are relatively easy to obtain. Methods. We used Galactic globular clusters (GCs) as our sample since they have relatively accurate binary fraction measurements and spectroscopic observations along the radial direction. When studying the relation between binary fractions and the spectral absorption feature index, we used three types of binary fractions: one with a mass ratio of q>0.5 (f(q>0.5)) and two with a total binary fraction (the methods of counting (f(tot)mf) and fitting (f(tot)mc), calculated and obtained the equivalent widths or magnitudes of 46 spectral absorption feature indices at three spectral resolutions (FWHMLick/IDS, 5, and 15 Å). Since the regions for the binary fraction measurements (photometric) and the spectroscopic observations are different, we used the method of constructing the radial binary-fraction profile to get the binary fractions corresponding to the regions in the spectroscopic observations. The construction of the radial binary-fraction profile was obtained by using the python curve_fit module to fit the measured and analytic binary fraction values. The analytic value was expressed by taking advantage of the King surface-density profile and the assumed forms with respect to the radial binary-fraction profile (linear, quadratic, exponential, and Gaussian). Results. We find that the low-resolution (15 Å) spec

关键词： Stars

A Scenario for Origin of Global 4 mHz Oscillations in Solar Corona

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arXiv 2025年

作者： Xue, Li Jiao, Chengliang Zhang, Lixin Department of Astronomy Xiamen Univesity Xiamen361005 China Yunnan Observatories Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China

We establish a spherically symmetric model of solar atmosphere, which consists of the whole chromosphere and low corona below the 1.25 solar radius. It is a hydrodynamic model with heating in the chromosphere through an artificial energy flux. We performed a series of simulations with our model and found oscillations with a peak frequency of ∼4 mHz in the power spectrum. We confirmed that this resulted from the p-mode excited in the transition region and amplified in a resonant cavity situated in the height range ∼4 × 103-2 × 104 km. This result is consistent with global observations of Alfvénic waves in corona and can naturally explain the observational ubiquity of 4 mHz without the difficulty of the p-mode passing through the acoustic-damping chromosphere. We also confirmed that acoustic shock waves alone cannot heat the corona to the observed temperature, and found mass upflows in the height range ∼7 × 103-7 × 104 km in our model, which pumped the dense and cool plasma into the corona and might be the mass supplier for solar prominences. © 2025, CC BY.

关键词： Plasma shock waves