New Astronomy最新文献_第6页

Mass–radius relationship of strongly magnetized deformed white dwarfs 强磁化变形白矮星的质量-半径关系

IF 1.9 4区物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS

New Astronomy

Pub Date : 2025-07-02 DOI: 10.1016/j.newast.2025.102450

Rajasmita Sahoo , Tambe Pranjal Anant , Somnath Mukhopadhyay

The masses and radii of strongly magnetized anisotropic deformed white dwarf stars are investigated using the stellar structure equations in the parameterized

γ

-metric formalism. The Equation of State (EoS) of a completely degenerate relativistic electron gas in strong quantizing density-dependent magnetic field is developed. The fluid and field pressure anisotropy among the parallel and perpendicular components to the magnetic field is taken into consideration. This anisotropy in the EoS causes axisymmetric deformation of the star. We found stable solutions of deformed super-Chandrasekhar ultramassive white dwarfs. At a fixed central electron number density, the mass first increases from the traditional Chandrasekhar limit with increase of central magnetic field strength, reaches a maximum and then decreases with further increase of central magnetic field. For lower central magnetic field strengths, both the pressure anisotropy and the resulting deformation are very less, and hence the mass increases. In the higher central magnetic field regime, the magnetic field pressure anisotropy becomes significantly strong. This leads to greater deformation from spherical symmetry and hence reduces the stellar mass. We also see that the maximum mass and its corresponding equatorial radius both decrease as central magnetic field strength increases. We also notice that the maximum mass occurs at higher central density as the magnetic field increases. These phenomena also occur because of the deviation from spherical symmetry due to higher pressure anisotropy. High magnetic field increases stellar compactness.

利用参数化γ-度量形式的恒星结构方程，研究了强磁化各向异性变形白矮星的质量和半径。建立了强量子化密度相关磁场中完全简并相对论性电子气体的态方程。考虑了磁场平行分量和垂直分量的流体和场压力各向异性。EoS的这种各向异性导致了恒星的轴对称变形。我们找到了变形的超级钱德拉塞卡超大质量白矮星的稳定解。在一定的中心电子数密度下，随着中心磁场强度的增加，质量首先从传统的钱德拉塞卡极限开始增加，达到最大值，然后随着中心磁场的进一步增加而减小。当中心磁场强度较低时，压力各向异性和产生的变形都很小，因此质量增加。在较高的中心磁场区，磁场压力各向异性明显增强。这导致了更大的球面对称变形，从而减少了恒星质量。我们还看到，随着中心磁场强度的增加，最大质量及其相应的赤道半径都减小。我们还注意到，随着磁场的增加，最大质量出现在较高的中心密度处。这些现象也会发生，因为压力各向异性较高而偏离了球对称。高磁场增加了恒星的致密性。

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引用次数: 0

Libration points for ER3BP with triaxial and radiating bodies and numerical integration using Lie series 三轴和辐射体ER3BP的振动点及李氏级数的数值积分

IF 1.9 4区物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS

New Astronomy

Pub Date : 2025-06-30 DOI: 10.1016/j.newast.2025.102448

A. Chakraborty

This paper examines the Elliptic Restricted Three Body Problem (ER3BP) in which the primaries are triaxial radiating bodies. Using both analytical and numerical techniques, the problem’s planar equilibrium locations were obtained. For specific triaxiality values, it was found that there are more than five classically identified equilibrium locations. Additionally, a comparison of the equilibrium points’ positions as determined analytically and numerically was conducted. In order to determine the problem’s solution, the formulation of the iterative expression for the Lie series terms was expanded in the final section. The impact of the primaries’ triaxiality on the orbit is depicted graphically in the Lie series solution of triangular equilibria.

本文研究了原色为三轴辐射体的椭圆型受限三体问题。采用解析和数值相结合的方法，得到了问题的平面平衡位置。对于特定的三轴性值，发现有五个以上的经典确定的平衡位置。此外，还对解析法和数值法确定的平衡点位置进行了比较。为了确定问题的解，在最后一节对李级数项的迭代表达式进行了展开。在三角平衡的李级数解中，用图形描述了原星的三轴性对轨道的影响。

引用次数: 0

In-depth analysis of the light curve and first orbital period of contact binary GM Dra 深入分析了接触双星GM - Dra的光曲线和第一轨道周期

IF 1.9 4区物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS

New Astronomy

Pub Date : 2025-06-25 DOI: 10.1016/j.newast.2025.102445

M.F. Yıldırım

This study presents the light curve (LC) analysis of the GM Dra eclipsing binary (using data from TESS, SuperWASP, KWS(

I_{c}

), Hipparcos, and ASAS-SN), along with a detailed investigation of its orbital period (OP) for the first time. Photometric data obtained from five different databases were used to simultaneously analyze the system’s LC and radial velocity (RV). The LC modeling results for GM Dra reveal the object stars’ masses and radii as follows:

M_{1} = 0.28 \pm 0.01

M

_{⊙}

,

M_{2} = 1.34 \pm 0.02

M

_{⊙}

,

R_{1} = 0.64 \pm 0.01

R

_{⊙}

, and

R_{2} = 1.27 \pm 0.02

R

_{⊙}

. A total of 108 eclipse times (ETs) were calculated on the basis of TESS and SuperWASP observations. These ETs are of great significance in determining the OP change. The OP of the GM Dra has been analyzed based on long-term observations, revealing that the OP of GM Dra is decreasing by 0.051 s per year. A sinusoidal variation in the period change was also identified, which may be attributed to the presence of a potential third object or magnetic activity. These findings provide significant insights into the evolutionary status (the positions of the system in the Hertzsprung–Russell (HR) diagram and logM

_{t o t .}

–logJ diagram were discussed) of GM Dra and the dynamics of the binary system.

本文首次利用TESS、SuperWASP、KWS（Ic）、Hipparcos和ASAS-SN卫星的数据，对GM Dra食双星进行了光曲线（LC）分析，并对其轨道周期（OP）进行了详细的研究。从五个不同的数据库中获得的光度数据同时用于分析系统的LC和径向速度（RV）。对GM Dra的LC建模结果显示，目标恒星的质量和半径分别为：M1=0.28±0.01 M⊙,M2=1.34±0.02 M⊙,R1=0.64±0.01 R⊙,R2=1.27±0.02 R⊙。根据TESS和SuperWASP的观测结果，共计算了108次日食次数。这些ETs对于确定OP变化具有重要意义。在长期观测的基础上，对青藏高原的OP进行了分析，结果表明，青藏高原的OP以每年0.051 s的速度递减。周期变化的正弦变化也被确定，这可能归因于潜在的第三个物体或磁活动的存在。这些发现对进化状态（系统在赫茨普龙-罗素（HR）图和logMtot中的位置）提供了重要的见解。讨论了GM - Dra的-logJ图和二元体系的动力学。

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引用次数: 0

Multi-point observation of a CME on August 16, 2020 2020年8月16日CME的多点观测

IF 1.9 4区物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS

New Astronomy

Pub Date : 2025-06-25 DOI: 10.1016/j.newast.2025.102446

Marcel Nogueira de Oliveira , Carlos E. Navia , Andre Asevedo Nepomuceno

On August 16, 2020, at 17:12 UT, a long-duration B1.2-class flare erupted from a filament in the southeastern hemisphere, originating from an active region at

32 °

S,

26 °

E, near a large equatorial coronal hole (CH). According to LASCO coronagraph images from the L1 point, the associated CME erupted with a principal angle (PA) of approximately

99 °

, close to the ecliptic plane, and at a speed of 437 km/s. Consequently, the Lorentz force between the CH’s magnetic field and the CME deflected the CME about

30 °

northward. NOAA’s CME propagation models predicted a possible impact on Earth on August 19 around 22:00 UT. However, no signs of the CME were detected at Earth. Meanwhile, STEREO-A observed a disturbance in the solar wind around 19:00 UT, consistent with a CME impact. Considering that the magnetic field and solar wind plasma move together (i.e., under the frozen-in flux condition), and due to the Sun’s rotation, parcels of solar wind plasma spiral outward from the Sun (forming the Parker spiral). The solar wind spiral motion dragged the CME, deflecting it approximately

30 °

eastward during its propagation to 1 AU, ultimately directing it toward STEREO-A’s location. Furthermore, remote-tracking observations from the two broadband visible-light refracting camera systems (HI-1 and HI-2) aboard STEREO-A captured the CME in J-plot images, tracking it from its eruption to its impact. Additionally, the bi-directional flow of suprathermal electrons observed by STEREO-A during the first 12 h of August 19, 2020, indicates that the CME crossed a high-speed stream (HSS) sector. An isotropic flux of suprathermal electrons observed around 19:00 UT further confirms the CME’s impact in STEREO-A’s vicinity.

2020年8月16日，UT 17:12，东半球的一根灯丝爆发了一场持续时间很长的b2级耀斑，起源于32°S， 26°E的活跃区域，靠近一个大的赤道日冕洞（CH）。根据LASCO日冕仪从L1点拍摄的图像，相关CME喷发的主角（PA）约为99°，靠近黄道面，速度为437 km/s。因此，CH磁场和CME之间的洛伦兹力使CME向北偏转约30°。美国国家海洋和大气管理局的CME传播模型预测了8月19日22:00左右可能对地球产生的影响。然而，在地球上没有探测到CME的迹象。同时，STEREO-A在世界时19:00左右观测到太阳风的扰动，与CME撞击相一致。考虑到磁场和太阳风等离子体一起运动（即在通量冻结状态下），并且由于太阳的旋转，太阳风等离子体包裹从太阳向外旋转（形成帕克螺旋）。太阳风的螺旋运动拖着日冕物质抛射，在其传播到1天文单位的过程中向东偏转了大约30°，最终将其导向STEREO-A的位置。此外，STEREO-A上的两个宽带可见光折射相机系统（HI-1和HI-2）的远程跟踪观测以J-plot图像捕获了CME，跟踪了它从喷发到撞击的过程。此外，STEREO-A在2020年8月19日的前12小时观测到的超热电子双向流动表明，CME穿过了高速流（HSS）扇区。在世界时19:00左右观测到的超热电子的各向同性通量进一步证实了CME对STEREO-A附近的影响。

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引用次数: 0

Predicting the detectability of gravitational waves from PSR J0737–3039 with the laser interferometer space antenna: A quadrupole approximation approach 用激光干涉仪空间天线预测PSR J0737-3039引力波的可探测性：四极逼近方法

IF 1.9 4区物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS

New Astronomy

Pub Date : 2025-06-21 DOI: 10.1016/j.newast.2025.102449

Zheng Zhou

Gravitational waves (GWs) are an important component of gravitational physics. In a binary system, it is emitted through orbital energy loss. In this paper, we explore the Laser Interferometer Space Antenna (LISA)’s detectability of gravitational waves from PSR J0737–3039, the first known binary pulsar system. The system is located around 1150 parsecs from Earth, with an orbital period of ∼2.45 h and an inclination angle of 87°, making it an ideal candidate for testing gravitational physics. We approximated the GW frequency of the system to be ∼2.26 × 10⁻⁴ Hz using rules of orbital frequency. We used the quadrupole formula, a part of the multipole expansion, to estimate that the calculated GW strains (h_✕ ∼ 4.8702×10⁻²³ and h₊ ∼ 4.6656×10⁻²²). The strain magnitudes fall below the detector noise curve of LISA. We offer possible explanations for this, including arm length and acceleration noise, while proposing methods to enhance LISA’s sensitivity. These methods include the Noise2Noise algorithm and possibility of the installation of resonant detectors.

引力波（GWs）是引力物理学的重要组成部分。在双星系统中，它是通过轨道能量损失发射的。在本文中，我们探索了激光干涉仪空间天线（LISA）对来自PSR J0737-3039的引力波的可探测性，这是已知的第一个双星脉冲星系统。该系统位于距离地球1150秒差距左右，轨道周期为~ 2.45 h，倾角为87°，使其成为测试引力物理的理想候选者。我们使用轨道频率规则将系统的GW频率近似为~ 2.26 × 10−4 Hz。我们使用四极公式（多极展开的一部分）来估计计算出的GW应变（h✕~ 4.8702×10−23和h+ ~ 4.6656×10−22）。应变幅值落在LISA探测器噪声曲线以下。我们提供了可能的解释，包括臂长和加速度噪声，同时提出了提高LISA灵敏度的方法。这些方法包括Noise2Noise算法和安装谐振检测器的可能性。

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引用次数: 0

uvby−Hβ Photoelectric photometry of 65 A/F-type candidate stars in the Kepler field: Observations, stellar parameters and variability analysis 开普勒场65颗A/ f型候选恒星的uvby−Hβ光电光度测定：观测、恒星参数和变异性分析

IF 1.9 4区物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS

New Astronomy

Pub Date : 2025-06-18 DOI: 10.1016/j.newast.2025.102436

L. Fox-Machado , J.H. Peña , B. Smalley

We present the results of

u v b y - H_{β}

photoelectric photometry for 65 stars in the Kepler field, focusing on the study of

δ

Scuti,

γ

Doradus, and hybrid-type stars. The observing procedures and methodology used to derive the Strömgren indices and colors

V

,

(b - y)

,

m_{1}

,

c_{1}

, and

H_{β}

are described in detail. We identify dwarfs and giants within the sample and report their physical parameters. For 47 stars,

T_{eff}

and

log g

determined from our indices were previously reported by Uytterhoeven et al. (2011), while for the remaining stars, these parameters are provided in this work. Additionally, we revisit the variability classifications of these stars by analyzing all available Kepler and TESS light curves and confirm most of the pulsation classifications assigned in previous studies.

本文报道了开普勒区65颗恒星的uvby−Hβ光电光度测量结果，重点研究了δ Scuti、γ Doradus和混合型恒星。详细描述了用于推导Strömgren指数和颜色V，（b−y）， m1， c1和Hβ的观察程序和方法。我们在样本中识别矮星和巨人，并报告它们的物理参数。其中47颗恒星的Teff和log由我们的指数确定，已由Uytterhoeven et al.（2011）报道，其余恒星的参数由本文提供。此外，通过分析所有可用的开普勒和TESS光曲线，我们重新审视了这些恒星的变异性分类，并确认了之前研究中分配的大部分脉动分类。

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引用次数: 0

Warped accretion disk with power-law models for viscosities 翘曲吸积盘粘度幂律模型

IF 1.9 4区物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS

New Astronomy

Pub Date : 2025-06-15 DOI: 10.1016/j.newast.2025.102447

F.S. Mohseni, A. Khosravi

In this paper, we investigate a thin accretion disk that is warped due to the Black hole spin using numerical methods. We assume that the two viscosity coefficients vary with radius according to a power-law model, each with different power indices. Additionally, we consider the contribution of the inner disk by applying the appropriate boundary condition. Our results indicate that the alignment of the disk is influenced by the power indices of the viscosities (n and α₁). Specifically, the vertical viscosity index is more influential than the azimuthal viscosity index. An increase in the vertical viscosity index leads to greater misalignment of the disk concerning the spin axis of the black hole. These findings suggest that, contrary to previous studies, the inner regions of the disk can remain tilted relative to the rotation axis of the black hole, even for rotating black holes with a larger Kerr parameter, specifically, a = 0.3. Our results help explain the observed quasi-periodic oscillation features in X-ray emissions and the Fe Kα line, which may arise from the precession of a warped inner accretion disk. This research could be valuable for exploring regions of strong gravitational fields.

在本文中，我们用数值方法研究了由于黑洞自旋而扭曲的薄吸积盘。我们假设两个黏度系数根据幂律模型随半径变化，各有不同的幂指数。此外，我们通过应用适当的边界条件来考虑内盘的贡献。结果表明，黏度的幂指数（n和α1）对圆盘的排列有影响。具体而言，垂直粘度指数比方位粘度指数的影响更大。垂直粘度指数的增加导致圆盘与黑洞自转轴的更大偏差。这些发现表明，与之前的研究相反，盘的内部区域可以相对于黑洞的旋转轴保持倾斜，即使对于具有较大Kerr参数的旋转黑洞，特别是a = 0.3。我们的研究结果有助于解释观测到的x射线辐射和Fe - k - α线的准周期振荡特征，这可能是由扭曲的内部吸积盘进动引起的。这项研究可能对探索强引力场区域有价值。

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引用次数: 0

Detection of CRSF in Cep X-4 at a low luminosity level 低亮度水平下Cep X-4中CRSF的检测

IF 1.9 4区物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS

New Astronomy

Pub Date : 2025-06-13 DOI: 10.1016/j.newast.2025.102435

Kinjal Roy , Rahul Sharma

The BeXRP Cep X-4 underwent a type II outburst during July 2023, during which NuSTAR made two observations of the source. In this paper, we present the spectral and timing analysis of Cep X-4 during this outburst. Pulsations were detected from the source at the neutron star spin period of

\sim

66 s from both observations. We detected a CRSF feature at an energy of

27 . 3_{- 1.0}^{+ 1.5}

keV in the spectrum of Cep X-4 during the first observation. In the second observation conducted a day later when the source luminosity dropped by a factor of five, no CRSF could be detected significantly. A positive correlation between CRSF energy and luminosity was observed using data from multiple outbursts since 1998. The collisionless shock model provides a good fit to the observed variations of cyclotron line energy with luminosity, giving a surface magnetic field strength of

\sim 2.6 \times

1 0^{12}

G.

BeXRP Cep X-4在2023年7月经历了一次II型爆发，在此期间，核星对源进行了两次观测。本文给出了Cep X-4爆发时的光谱和时间分析。两次观测都在中子星自旋周期为~ 66 s时从源处探测到脉动。在Cep X-4的第一次观测中，我们发现了能量为27.3−1.0+1.5 keV的CRSF特征。在一天后的第二次观测中，当光源亮度下降了五倍时，没有明显的CRSF检测到。利用1998年以来多次爆发的数据观测到CRSF能量与光度正相关。无碰撞激波模型很好地拟合了观测到的回旋加速器线能量随光度的变化，给出了表面磁场强度为~ 2.6× 1012 G。

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引用次数: 0

Star formation rate estimations of a mid-infrared sample of X-ray selected nearby Active Galactic Nuclei 选取活动星系核附近的中红外x射线样本的恒星形成速率估计

IF 1.9 4区物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS

New Astronomy

Pub Date : 2025-06-04 DOI: 10.1016/j.newast.2025.102433

Angel Castro , Takamitsu Miyaji , Liliana Altamirano-Dévora , Peter Boorman , Kohei Ichikawa , Matthew Malkan , Héctor Aceves , Yoshihiro Ueda , Erika Castillo , Mauricio Elías-Chavez , Irene Cruz-González , Martín Herrera-Endoqui , Takao Nakagawa

We investigate the activity of active galactic nuclei and the circumnuclear star formation properties in a nearby (

z \leq 0.1

) sample of 125 hard X-ray (14–195 keV) selected active Galactic Nuclei (AGN) from the Swift/BAT 70-month survey catalogue. Using the 11.3

μ m

polycyclic aromatic hydrocarbon (PAH) emission feature measured with the Spitzer/IRS instrument as a proxy for recent star formation, we examine the relationship between AGN power and circumnuclear star formation rate (SFR). We explored the SFR properties of both type-1 and type-2 AGN populations within our sample. A positive correlation is found between hard X-ray luminosity (

L_{X}

) and SFR for our sample but not for type-2 AGN alone. In comparing type-1 and type-2 sources, we found no significant differences between our sample’s low- and high-luminosity populations. For a subset of 50 AGN, we also provide AKARI/IRC measurements of the 3.3

μ m

PAH emission feature, which were used to estimate SFR. Although some correlations are present, these samples’ two types of AGN cannot be clearly distinguished based solely on their luminosity or SFR properties as indicated by their PAH emission.

我们从Swift/BAT 70个月的巡天目录中选择了125硬x射线（14-195 keV）的活动星系核（AGN），研究了活动星系核的活动和环核恒星形成特性。利用Spitzer/IRS仪器测量的11.3 μm多环芳烃（PAH）发射特征作为近期恒星形成的代表，我们研究了AGN功率与环核恒星形成速率（SFR）之间的关系。我们探索了样本中1型和2型AGN群体的SFR特性。硬x射线亮度（LX）与SFR之间存在正相关关系，但与2型AGN无关。在比较1型和2型光源时，我们发现样本的低亮度和高亮度群体之间没有显著差异。对于50 AGN的子集，我们还提供了3.3 μm PAH发射特征的AKARI/IRC测量，用于估计SFR。尽管存在一些相关性，但这些样品的两种AGN类型不能仅根据其光度或SFR特性（由其多环芳烃发射表明）来明确区分。

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引用次数: 0

Mapping the reddening plane in the Galactic disk through interstellar extinction of open clusters 通过疏散星团的星际消光绘制银河系盘中的变红平面

IF 1.9 4区物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS

New Astronomy

Pub Date : 2025-06-02 DOI: 10.1016/j.newast.2025.102425

Y.C. Joshi

As thousands of new open clusters in the Galaxy have recently been reported with reddening or extinction information, we map the distribution and properties of the MilkyWay’s interstellar material in the Galactic disk as traced by these open clusters. By analyzing the distribution of interstellar extinction for 6215 open clusters located at low Galactic latitude (

| b | \leq 6 °

), corresponding to the thin Galactic disk, we identify a reddening plane characterized by a dust layer whose thickness varies with Galactic longitude. By splitting the open clusters sample into several sub-regions of Galactic longitude, we observe that the reddening plane is not perfectly aligned with the formal Galactic plane, but instead varies sinusoidally around the Galactic mid-plane. The maximum and minimum interstellar absorption occur at approximately

42 °

and

222 °

, respectively, along the Galactic longitude. Our analysis reveals a noticeable north-south asymmetry in the distribution of interstellar absorption, with a higher proportion of interstellar material below the Galactic plane. We also find that the Sun is located

15.7 \pm 7.3

pc above the reddening plane. The scale height of the open clusters from the reddening plane is estimated to be

z_{h} = 87.3 \pm 1.8

pc. The mean thickness of the absorbing material in the reddening plane, which represents the average extent of the dust layer responsible for interstellar extinction, is found to be about

201 \pm 20

pc. Our findings provide insights into the distribution of interstellar dust, its relationship with the Galactic thin disk, and its implications on the Galactic structure.

由于最近报道了银河系中数千个新的疏散星团的变红或消失信息，我们绘制了由这些疏散星团追踪的银河系盘中星际物质的分布和性质。通过分析6215个位于低银纬（|b|≤6°）的疏散星团的星际消光分布，我们确定了一个以尘埃层为特征的变红平面，其厚度随银经变化。通过将疏散星团样本分成银河系经度的几个子区域，我们观察到变红的平面并不完全与正式的银河系平面对齐，而是围绕银河系中平面呈正弦变化。最大和最小的星际吸收分别发生在沿银河系经度约42°和222°处。我们的分析揭示了星际吸收分布中明显的南北不对称，银河平面以下的星际物质比例更高。我们还发现太阳位于变红平面上方15.7±7.3 pc。从变红平面出发，疏散星团的尺度高度估计为zh=87.3±1.8 pc。在变红的平面上，吸收物质的平均厚度约为201±20pc，这代表了星际消光的尘埃层的平均范围。我们的发现提供了对星际尘埃分布的见解，它与银河系薄盘的关系，以及它对银河系结构的影响。

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引用次数: 0