New Astronomy最新文献_第3页

Equilibrium points in the perturbed rotating mass dipole system with oblateness

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

New Astronomy

Pub Date : 2024-12-16 DOI: 10.1016/j.newast.2024.102344

Bess Rioborue Agbogidi , Aguda Ekele Vincent , Benson Ade Eniola Afere , Sani Doro Ibrahim

This paper discusses the existence, location, and liner stability of equilibrium points around a rotating dipole in the framework of the circular restricted three-body problem. The rotating dipole system consists of two finite bodies of masses

m_{1}

and

m_{2}

rigidly connected by a massless rod in a constant characteristic distance. The idea is to consider that the bigger primary body is an oblate spheroid and the smaller one is a point mass together with small perturbations in the Coriolis and centrifugal forces of the primaries. Firstly, these equilibria are determined numerically and, depending on the force ratio and mass factor values, their number may be three or five. It is found that the positions of these equilibria depend on all the system parameters except small perturbation in the Coriolis force. The linear stability of each equilibrium point is also examined. A simulation is done by using two typical highly irregular shaped asteroids, 216-Kleopatra and 1620-Geographos, for which it is found that three collinear and two non-collinear equilibria exist for each system. The positions of these equilibria and their stability as well as the zero-velocity curves under variations of the aforementioned perturbations have been determined numerically. It is seen that the positions of the equilibria are affected by the parameters of the problem, since they are shifted from the classical restricted three-body problem on the

x

–axis and out of the

x

–axis, respectively. The linear stability of these equilibria is investigated for the asteroid systems, and they are found to be linearly unstable.

{"title":"Equilibrium points in the perturbed rotating mass dipole system with oblateness","authors":"Bess Rioborue Agbogidi , Aguda Ekele Vincent , Benson Ade Eniola Afere , Sani Doro Ibrahim","doi":"10.1016/j.newast.2024.102344","DOIUrl":"10.1016/j.newast.2024.102344","url":null,"abstract":"<div><div>This paper discusses the existence, location, and liner stability of equilibrium points around a rotating dipole in the framework of the circular restricted three-body problem. The rotating dipole system consists of two finite bodies of masses <span><math><msub><mrow><mi>m</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> and <span><math><msub><mrow><mi>m</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> rigidly connected by a massless rod in a constant characteristic distance. The idea is to consider that the bigger primary body is an oblate spheroid and the smaller one is a point mass together with small perturbations in the Coriolis and centrifugal forces of the primaries. Firstly, these equilibria are determined numerically and, depending on the force ratio and mass factor values, their number may be three or five. It is found that the positions of these equilibria depend on all the system parameters except small perturbation in the Coriolis force. The linear stability of each equilibrium point is also examined. A simulation is done by using two typical highly irregular shaped asteroids, 216-Kleopatra and 1620-Geographos, for which it is found that three collinear and two non-collinear equilibria exist for each system. The positions of these equilibria and their stability as well as the zero-velocity curves under variations of the aforementioned perturbations have been determined numerically. It is seen that the positions of the equilibria are affected by the parameters of the problem, since they are shifted from the classical restricted three-body problem on the <span><math><mi>x</mi></math></span>–axis and out of the <span><math><mi>x</mi></math></span>–axis, respectively. The linear stability of these equilibria is investigated for the asteroid systems, and they are found to be linearly unstable.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"116 ","pages":"Article 102344"},"PeriodicalIF":1.9,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143095037","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

Continuous O ’Connell effect and period variations of solar-like totally eclipsing contact binary BO Ari

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

New Astronomy

Pub Date : 2024-12-15 DOI: 10.1016/j.newast.2024.102341

Meng Guo , Jingjing Wang , Jing Zhang , Xiaoman Tian

We obtained newly BV

R_{c} I_{c}

light curves for the contact binary BO Ari in 2023. The multi-color light curves were analyzed using the Wilson–Devinney (2013) program, which solutions reveal that BO Ari is a middle contact binary with q = 0.1778, f = 48% and a small temperature difference of 92 K. All minimum times were collected to re-calculated O-C. The O-C curves show a cyclic oscillation (

A_{3}

= 0.00337 d,

T_{3}

= 16.35 yr) superimposed on a long-term decreasing (dP/dt =

- 1.63 \times 1 0^{- 7}

d

{yr}^{- 1}

). This secular period decrease may be due to mass transfer from the more massive component to the less massive one. The cyclic trend was explained by the light-travel time effect due to the presence of a third body or magnetic activity. With this long-term mass transferring, the fill-out degree will increase. Furtherly, BO Ari will evolve into a deeply contact binary. In addition, during the monitoring of the space telescope Transiting Exoplanet Survey Satellite (TESS), it is the first time to discover continuous variation of the O’Connell effect in each cycle, obviously the positive O’Connell effect changes to a negative one over a short time. These phenomena imply the presence of possible magnetic activity on the surface of the component. Based on these fitting parameters, the hot spot and dark spot were found on the components.

{"title":"Continuous O ’Connell effect and period variations of solar-like totally eclipsing contact binary BO Ari","authors":"Meng Guo , Jingjing Wang , Jing Zhang , Xiaoman Tian","doi":"10.1016/j.newast.2024.102341","DOIUrl":"10.1016/j.newast.2024.102341","url":null,"abstract":"<div><div>We obtained newly BV<span><math><mrow><msub><mrow><mi>R</mi></mrow><mrow><mi>c</mi></mrow></msub><msub><mrow><mi>I</mi></mrow><mrow><mi>c</mi></mrow></msub></mrow></math></span> light curves for the contact binary BO Ari in 2023. The multi-color light curves were analyzed using the Wilson–Devinney (2013) program, which solutions reveal that BO Ari is a middle contact binary with <em>q</em> = 0.1778, <em>f</em> = 48% and a small temperature difference of 92 K. All minimum times were collected to re-calculated <em>O-C</em>. The <em>O-C</em> curves show a cyclic oscillation (<span><math><msub><mrow><mi>A</mi></mrow><mrow><mn>3</mn></mrow></msub></math></span> = 0.00337 d, <span><math><msub><mrow><mi>T</mi></mrow><mrow><mn>3</mn></mrow></msub></math></span> = 16.35 yr) superimposed on a long-term decreasing (<em>dP/dt</em> = <span><math><mrow><mo>−</mo><mn>1</mn><mo>.</mo><mn>63</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>7</mn></mrow></msup></mrow></math></span> d <span><math><msup><mrow><mi>yr</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></math></span>). This secular period decrease may be due to mass transfer from the more massive component to the less massive one. The cyclic trend was explained by the light-travel time effect due to the presence of a third body or magnetic activity. With this long-term mass transferring, the fill-out degree will increase. Furtherly, BO Ari will evolve into a deeply contact binary. In addition, during the monitoring of the space telescope Transiting Exoplanet Survey Satellite (TESS), it is the first time to discover continuous variation of the O’Connell effect in each cycle, obviously the positive O’Connell effect changes to a negative one over a short time. These phenomena imply the presence of possible magnetic activity on the surface of the component. Based on these fitting parameters, the hot spot and dark spot were found on the components.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"116 ","pages":"Article 102341"},"PeriodicalIF":1.9,"publicationDate":"2024-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143103877","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

Orbital period variation of W UMa binary star V2802 Orionis

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

New Astronomy

Pub Date : 2024-12-13 DOI: 10.1016/j.newast.2024.102343

Ronnakrit Rattanamala , Pornapa Artsang , Supachai Awiphan

This study investigates the orbital period variation and physical parameters of the eclipsing binary system V2802 Orionis. Observations were conducted at the Regional Observatory for the Public, Nakhon Ratchasima (ROP-NMA), under the National Astronomical Research Institute of Thailand (NARIT), using Johnson-Cousins B, V, R_C, and I_C filters. Light curves obtained between 2021 and 2023 were analyzed with the Wilson–Devinney (W-D) code, revealing a mass ratio of q = 2.902(±0.006), an inclination of i = 88.6(±0.4) degree, and a secondary star temperature T₂ = 5030(±3) K. Our results indicate that V2802 Orionis is a W-type W UMa binary star with a shallow degree of contact (16.6 %) and variability due to a spot on the primary component. The orbital period shows a secular decrease at a rate of 1.12(±0.09)×10⁻⁷ day year⁻¹, attributed to mass transfer from the more massive to the less massive component. Additionally, a period variation with a cycle 5.1(±0.1) years suggests the presence of a third body, with a mass of 0.14(±0.01) M_☉ and a separation of 3.2(±0.1) AU from the binary system. The masses, radii, and luminosities of the primary and secondary stars are estimated as M₁ = 0.65(±0.001) M_☉, M₂ = 0.77 M_☉, R₁ = 0.56(±0.01) R_☉, R₂ = 0.91(±0.01) R_☉, L₁ = 0.21(±0.01) L_☉, and L₂ = 0.48(±0.01) L_☉. Evolutionary analysis on the Hertzsprung-Russell diagram shows that the primary star (less massive) has evolved away from the main-sequence, while the secondary (more massive) remains on the main sequence star.

{"title":"Orbital period variation of W UMa binary star V2802 Orionis","authors":"Ronnakrit Rattanamala , Pornapa Artsang , Supachai Awiphan","doi":"10.1016/j.newast.2024.102343","DOIUrl":"10.1016/j.newast.2024.102343","url":null,"abstract":"<div><div>This study investigates the orbital period variation and physical parameters of the eclipsing binary system V2802 Orionis. Observations were conducted at the Regional Observatory for the Public, Nakhon Ratchasima (ROP-NMA), under the National Astronomical Research Institute of Thailand (NARIT), using Johnson-Cousins <em>B, V, R</em><sub>C</sub>, and <em>I</em><sub>C</sub> filters. Light curves obtained between 2021 and 2023 were analyzed with the Wilson–Devinney (W-D) code, revealing a mass ratio of <em>q</em> = 2.902(±0.006), an inclination of <em>i</em> = 88.6(±0.4) degree, and a secondary star temperature <em>T</em><sub>2</sub> = 5030(±3) K. Our results indicate that V2802 Orionis is a W-type W UMa binary star with a shallow degree of contact (16.6 %) and variability due to a spot on the primary component. The orbital period shows a secular decrease at a rate of 1.12(±0.09)×10<sup>−7</sup> day year<sup>−1</sup>, attributed to mass transfer from the more massive to the less massive component. Additionally, a period variation with a cycle 5.1(±0.1) years suggests the presence of a third body, with a mass of 0.14(±0.01) M<sub>☉</sub> and a separation of 3.2(±0.1) AU from the binary system. The masses, radii, and luminosities of the primary and secondary stars are estimated as <em>M</em><sub>1</sub> = 0.65(±0.001) M<sub>☉</sub>, <em>M</em><sub>2</sub> = 0.77 M<sub>☉</sub>, <em>R</em><sub>1</sub> = 0.56(±0.01) R<sub>☉</sub>, <em>R</em><sub>2</sub> = 0.91(±0.01) R<sub>☉</sub>, <em>L</em><sub>1</sub> = 0.21(±0.01) L<sub>☉</sub>, and <em>L</em><sub>2</sub> = 0.48(±0.01) L<sub>☉</sub>. Evolutionary analysis on the Hertzsprung-Russell diagram shows that the primary star (less massive) has evolved away from the main-sequence, while the secondary (more massive) remains on the main sequence star.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"116 ","pages":"Article 102343"},"PeriodicalIF":1.9,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143103876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Estimation of classical Cepheid’s physical parameters from NIR light curves

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

New Astronomy

Pub Date : 2024-12-12 DOI: 10.1016/j.newast.2024.102317

Lajos G. Balázs , Gábor B. Kovács

Recent space-borne and ground-based observations provide photometric measurements as time series. The data points are nearly continuous over a limited observational interval or randomly scattered over a long period. The effect of interstellar dust extinction in the near-infrared range is only 10% of that measured in the visual (V) range. However, the sensitivity of the light curve shape to the physical parameters in the near-infrared is significantly lower. So, interpreting these types of data sets requires new approaches like the different large-scale surveys, which create similar problems with big data. Using a selected data set, we provide a method for applying routines implemented in R to extract most information of measurements to determine physical parameters, which can also be used in automatic classification schemes and pipeline processing.

We made a multivariate classification of 131 Cepheid light curves (LC) in J,H, and K colors by applying routines of R, where all the LCs were represented in 20D parameter space in these colors separately. Performing a Principal Component Analysis (PCA), we got an orthogonal coordinate system and squared Euclidean distances between LCs. The PCA resulted in 6 significant eigenvalues, which allowed us to reduce the 20-dimension to 6. We also estimated the optimal number of partitions of similar objects and obtained it equal to 7 in each color; their dependence on the period, absolute magnitude, amplitude, and metallicity are also discussed. We computed the Spearman rank correlations, and concerning periods and absolute magnitudes, the first three PCs had correlations at a very high significance level. Similar computations revealed significant relationships between the amplitude and the first two PCs, but the LCs depend only marginally on the metallicity in H and K colors.

The method shown can be generalized and implemented in unsupervised classification schemes and analysis of mixed and biased samples. The analysis of a sample of classical Cepheids observed only in near-infrared bands resulted in the information coded in the light curves being insufficient to determine the stars’ metallicity and identified the mass as the dominating quantity to form the shape of LCs in our sample.

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引用次数: 0

Characterizing the spiral Lin–Shu-type density-wave structure of the Milky Way in the 3-kpc-scale solar neighborhood: Astrophysical conclusions

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

New Astronomy

Pub Date : 2024-12-06 DOI: 10.1016/j.newast.2024.102340

Evgeny Griv , Michael Gedalin , Luis Martinez-Medina , Angeles Pérez-Villegas , Ing-Guey Jiang

In the concluding work of a series of studies, the disk’s spiral structure of the Milky Way is anew considered as a Lin–Shu-type density-wave pattern. As a step forward, a sample of

\sim 500000

stars from a total of 656161 sources within 3 kpc from the Sun and

\pm 250

pc from the disk’s mean plane identified in the Gaia EDR3 is examined. The parameters of Galactic rotation and solar peculiar motion corrected for the effects of 3D density waves, and the radial, azimuthal, and vertical components of the streaming motion of stars due to the spiral arms are derived from the measured velocities of objects. The parameters of the waves are also estimated. Two almost equal scales of periodic compression/rarefaction irregularity of the streaming velocity field with the radial and vertical wavelengths of

≲ 2

kpc in the form of a spiral density wave propagating in the disk at the Sun are revealed, which are reasonably related to the global spiral pattern. The Sun is located between the central part and the inner edge of the Orion (Local) wave arm. The spiral pattern in the kinematics of stars is consistent with the spatial distribution of the nearby arm segments traced by young populations. In agreement with the original Lin and Shu proposal, the gravitational field associated with the arms is a small deviation from the total gravitational field of the Galaxy that is axisymmetric in the mean. The very existence of the spiral arrangement in the velocity field suggests that the localized disk is gravitationally unstable.

{"title":"Characterizing the spiral Lin–Shu-type density-wave structure of the Milky Way in the 3-kpc-scale solar neighborhood: Astrophysical conclusions","authors":"Evgeny Griv , Michael Gedalin , Luis Martinez-Medina , Angeles Pérez-Villegas , Ing-Guey Jiang","doi":"10.1016/j.newast.2024.102340","DOIUrl":"10.1016/j.newast.2024.102340","url":null,"abstract":"<div><div>In the concluding work of a series of studies, the disk’s spiral structure of the Milky Way is anew considered as a Lin–Shu-type density-wave pattern. As a step forward, a sample of <span><math><mrow><mo>∼</mo><mn>500000</mn></mrow></math></span> stars from a total of 656161 sources within 3 kpc from the Sun and <span><math><mrow><mo>±</mo><mn>250</mn></mrow></math></span> pc from the disk’s mean plane identified in the <em>Gaia</em> EDR3 is examined. The parameters of Galactic rotation and solar peculiar motion corrected for the effects of 3D density waves, and the radial, azimuthal, and vertical components of the streaming motion of stars due to the spiral arms are derived from the measured velocities of objects. The parameters of the waves are also estimated. Two almost equal scales of periodic compression/rarefaction irregularity of the streaming velocity field with the radial and vertical wavelengths of <span><math><mrow><mo>≲</mo><mn>2</mn></mrow></math></span> kpc in the form of a spiral density wave propagating in the disk at the Sun are revealed, which are reasonably related to the global spiral pattern. The Sun is located between the central part and the inner edge of the Orion (Local) wave arm. The spiral pattern in the kinematics of stars is consistent with the spatial distribution of the nearby arm segments traced by young populations. In agreement with the original Lin and Shu proposal, the gravitational field associated with the arms is a small deviation from the total gravitational field of the Galaxy that is axisymmetric in the mean. The very existence of the spiral arrangement in the velocity field suggests that the localized disk is gravitationally unstable.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"116 ","pages":"Article 102340"},"PeriodicalIF":1.9,"publicationDate":"2024-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143103874","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

Spectroscopic and photometric study for five late G- to K-type short-period contact binaries 五个晚G- k型短周期接触双星的光谱和光度研究

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

New Astronomy

Pub Date : 2024-11-26 DOI: 10.1016/j.newast.2024.102329

Qing Dong , Raúl Michel , Zhi-Hua Wang , Iván Mora Zamora

We reported spectroscopy and photometry for five ultra-short period W UMa-type contact binaries. Eleven sets of low resolution spectra are obtained from the Large Sky Area Multiobject Fiber Spectroscopic Telescope (LAMOST) database and analyzed. It has been determined that these systems are late G- to K-type stars: G7V for J0658, G9V for LINEAR 3562115, K0V for PS Com, and K5V for LINEAR 11570575. Additionally, it was observed that the cooler the star, the stronger the sodium absorption line. Seven sets of complete light curves, including two sets of TESS data for PS Com and V0568 Peg, were analyzed using the W-D code. All the five targets are W-subtype systems with mass ratios (

q

) greater than 1. The light curves of the two medium contact systems (J0658 and LINEAR 11570575) are symmetric. In contrast, the light curves of the three shallow contact binaries (LINEAR 3562115, PS Com, and V0568 Peg) show differences between their two maxima, Max.I and Max.II, suggesting the presence of cool or hot spots on their surfaces. According to the H-R diagram, the more massive components of these targets are situated between the ZAMS and TAMS, while the less massive ones are overheated due to energy transfer within the common envelope. As these binaries lose angular momentum, they will evolve into deep, low mass ratio contact binaries.

我们报告了五颗超短周期W UMa型接触双星的光谱和测光结果。我们从大天区多天体光纤光谱望远镜（LAMOST）数据库中获得了11组低分辨率光谱，并对其进行了分析。经测定，这些系统都是晚期G型到K型恒星：J0658为G7V，LINEAR 3562115为G9V，PS Com为K0V，LINEAR 11570575为K5V。此外，还观察到恒星温度越低，钠吸收线就越强。利用 W-D 代码分析了七组完整的光变曲线，包括 PS Com 和 V0568 Peg 的两组 TESS 数据。五个目标都是质量比（q）大于 1 的 W 亚型系统。两个中等接触系统（J0658 和 LINEAR 11570575）的光变曲线是对称的。相比之下，三个浅接触双星（LINEAR 3562115、PS Com和V0568 Peg）的光曲线在两个最大值（Max.I和Max.II）之间存在差异，这表明它们的表面存在冷点或热点。根据H-R图，这些目标中质量较大的部分位于ZAMS和TAMS之间，而质量较小的部分则由于共同包层内的能量转移而过热。随着这些双星失去角动量，它们将演变成深层的低质量比接触双星。

{"title":"Spectroscopic and photometric study for five late G- to K-type short-period contact binaries","authors":"Qing Dong , Raúl Michel , Zhi-Hua Wang , Iván Mora Zamora","doi":"10.1016/j.newast.2024.102329","DOIUrl":"10.1016/j.newast.2024.102329","url":null,"abstract":"<div><div>We reported spectroscopy and photometry for five ultra-short period W UMa-type contact binaries. Eleven sets of low resolution spectra are obtained from the Large Sky Area Multiobject Fiber Spectroscopic Telescope (LAMOST) database and analyzed. It has been determined that these systems are late G- to K-type stars: G7V for J0658, G9V for LINEAR 3562115, K0V for PS Com, and K5V for LINEAR 11570575. Additionally, it was observed that the cooler the star, the stronger the sodium absorption line. Seven sets of complete light curves, including two sets of TESS data for PS Com and V0568 Peg, were analyzed using the W-D code. All the five targets are W-subtype systems with mass ratios (<span><math><mi>q</mi></math></span>) greater than 1. The light curves of the two medium contact systems (J0658 and LINEAR 11570575) are symmetric. In contrast, the light curves of the three shallow contact binaries (LINEAR 3562115, PS Com, and V0568 Peg) show differences between their two maxima, Max.I and Max.II, suggesting the presence of cool or hot spots on their surfaces. According to the H-R diagram, the more massive components of these targets are situated between the ZAMS and TAMS, while the less massive ones are overheated due to energy transfer within the common envelope. As these binaries lose angular momentum, they will evolve into deep, low mass ratio contact binaries.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"116 ","pages":"Article 102329"},"PeriodicalIF":1.9,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142747807","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

A robust assessment of the local anisotropy of the Hubble constant in the Pantheon+ sample Pantheon+ 样本中哈勃常数局部各向异性的稳健评估

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

New Astronomy

Pub Date : 2024-11-23 DOI: 10.1016/j.newast.2024.102331

Yves-Henri Sanejouand

Magnitude predictions of

Λ

CDM, as parametrized by the Planck collaboration, are not consistent with the supernova Ia data of the whole Pantheon+ sample even when, in order to take into account the uncertainty about its value, the Hubble constant is adjusted. This is a likely consequence of the increase of the number of low-redshift supernovae in the Pantheon+ sample, with respect to previous such samples.

In order to find directions in the sky where the Hubble flow is quiet, that is, where model predictions are consistent with both low and high-redshift supernova data, predicted magnitudes of several models were compared to the corrected B band magnitudes of the supernovae of the Pantheon+ sample.

When supernovae at redshifts below 0.035 are ignored, with

H_{0} = 73.4

km

\cdot

s

^{- 1} \cdot

Mpc⁻¹,

Λ

CDM predictions become consistent with Pantheon+ data. This is also the case when subsets of low-redshift supernovae roughly centered on the direction of the CMB dipole are considered, together with high-redshift ones, at least when CMB and peculiar velocities corrections are taken into account for the redshifts. These results seem robust, since they are also obtained with a simple, single-parameter tired-light model.

由普朗克合作组织参数化的ΛCDM 的震级预测与整个 Pantheon+ 样本的 Ia 超新星数据并不一致，即使为了考虑其值的不确定性而调整了哈勃常数。这可能是 Pantheon+ 样本中低红移超新星的数量比以前的此类样本有所增加的结果。为了在天空中找到哈勃流平静的方向，也就是模型预测与低红移和高红移超新星数据都一致的方向，我们将几个模型的预测星等与Pantheon+样本中超新星的校正B波段星等进行了比较。当忽略红移低于0.035的超新星时，H0=73.4 km⋅s-1⋅Mpc-1, ΛCDM的预测与Pantheon+的数据变得一致。如果把大致以 CMB 偶极子方向为中心的低红移超新星子集与高红移超新星子集放在一起考虑，至少在考虑到 CMB 和奇特速度对红移的修正时，情况也是如此。这些结果似乎很可靠，因为它们也是用简单的单参数累光模型得到的。

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引用次数: 0

A comprehensive study on the K2-type binary V1393 Tau in four-year observations 通过四年观测对K2型双星V1393 Tau的综合研究

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

New Astronomy

Pub Date : 2024-11-13 DOI: 10.1016/j.newast.2024.102330

Ligang Yu , Shaung Wang , Michel Raúl , Liyun Zhang

We carried out a low resolution spectrum, the first ground-based multi-color light curves (LCs) analysis, and Transiting Exoplanet Survey Satellite (TESS) data analysis for the binary V1393 Tau. We determined its spectral type of K2V and updated an orbital period 0.24738715 days. By the Wilson-Devinney program, we solved ten sets of light curves. From the BVRcIc-band

L C_{2022.11}

, we obtained a mass ratio

q = 2.500 (3)

and a fill-out factor

f = 11.73 (6) %

, which implies that V1393 Tau is a W-type shallow-contact binary. We traced the spot migration and evolution through modeling light curves during the past four years. The spot’s size alternately becomes smaller or bigger, and its longitude intervenes between

λ = 82.3 9^{\circ}

in

L C_{S 70}

and

102.5 6^{\circ}

in

L C_{2022.10}

except for

L C_{S 32}

.

我们对双星V1393 Tau进行了低分辨率光谱、首次地基多色光曲线（LCs）分析和越轨系外行星巡天卫星（TESS）数据分析。我们确定其光谱类型为 K2V，并更新了其轨道周期为 0.24738715 天。通过威尔逊-德文尼程序，我们求解了十组光变曲线。通过BVRcIc波段LC2022.11，我们得到了质量比q=2.500(3)和填充因子f=11.73(6)%，这意味着V1393 Tau是一颗W型浅接触双星。我们通过建模光变曲线追踪了过去四年中光斑的迁移和演变过程。除LCS32外，光斑的大小交替变小或变大，其经度介于LCS70的λ=82.39∘和LC2022.10的102.56∘之间。

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引用次数: 0

The baryonic mass estimates of the Milky Way halo in the form of high-velocity clouds 高速云形式的银河系晕的重子质量估算

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

New Astronomy

Pub Date : 2024-11-07 DOI: 10.1016/j.newast.2024.102328

Noraiz Tahir , Martín López-Corredoira , Francesco De Paolis

The halo of our Galaxy is populated with a significant number of high-velocity clouds (HVCs) moving with a speed up to 500 km/s. It is suggested that these HVCs might contain a non-negligible fraction of the missing baryons. The main aim of the current paper is to estimate the baryonic mass of the Milky Way halo in the form of HVCs in order to constrain a fraction of missing baryons in the form of these clouds. Such findings would give substantial help in the studying halo dynamics of our Galaxy.

We first estimate the HVCs distance. We consider the most recent and updated HVC catalog, namely the Galactic All Sky Survey (GASS), which, however, covers the southern sky declinations, south of

b \leq 6 0^{\circ}

. Following a model presented in the literature, we assume that most of the HVCs (not all of the HVCs in the Milky Way) were ejected from the Magellanic Clouds (MCls) which is at a distance of about 50 kpc. We assume that the HVCs have a temperature in the range of about

1 0^{2}

–

1 0^{4}

K, and are distributed in the Galactic halo as the Navarro–Frenk–White (NFW) profile. Since the GASS survey covers a small portion of the sky, we estimate the number of missing clouds by using Monte Carlo (MC) simulations. The next step will be to estimate the total mass of the Milky Way contained in the form of these HVCs. The total mass resulted to be

\sim (7 \pm 2) \times 1 0^{9} M_{⊙}

in the form of HVCs and compact high-velocity clouds (CHVCs).

我们银河系的光环中存在着大量的高速云（HVCs），其运动速度高达每秒 500 公里。有人认为，这些高速云可能包含了不可忽略的一部分缺失重子。本文的主要目的是估算以高速云形式存在的银河光环的重子质量，以确定以这些云的形式存在的部分缺失重子。我们首先估算了HVCs的距离。我们首先估算了HVCs的距离。我们考虑了最新的HVC星表，即银河系全天空巡天（GASS），但它只覆盖了南部天空的偏角，即b≤60∘以南。根据文献中提供的模型，我们假定大部分 HVC（不是银河系中的所有 HVC）都是从麦哲伦云（MCls）中喷出的，麦哲伦云的距离约为 50 kpc。我们假定HVC的温度范围约为102-104 K，并以纳瓦罗-弗伦克-怀特（NFW）剖面的形式分布在银河晕中。由于 GASS 勘测只覆盖了一小部分天空，我们通过蒙特卡罗（Monte Carlo，MC）模拟来估计缺失云的数量。下一步将是估算这些 HVC 所包含的银河系总质量。结果显示，HVC和紧密高速云的总质量为(7±2)×109M⊙。

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引用次数: 0

Modifications of SPH towards three-dimensional simulations of an icy moon with internal ocean 对 SPH 进行修改，以实现具有内部海洋的冰质卫星的三维模拟

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

New Astronomy

Pub Date : 2024-11-02 DOI: 10.1016/j.newast.2024.102320

Keiya Murashima , Natsuki Hosono , Takayuki R. Saitoh , Takanori Sasaki

There are some traces of the existence of internal ocean in some icy moons, such as the vapor plumes of Europa and Enceladus. This implies a region of liquid water beneath the surface ice shell. Since liquid water would be essential for the origin of life, it is important to understand the development of these internal oceans, particularly their temperature distribution and evolution. The balance between tidal heating and radiative cooling is believed to sustain liquid water beneath an icy moon’s surface. We aim to simulate the tidal heating of an internal ocean in an icy moon using 3-dimensional numerical fluid calculations with the Smoothed Particle Hydrodynamics (SPH) method. We incorporated viscosity and thermal conduction terms into the governing equations of SPH. However, we encountered two issues while calculating rigid body rotation using SPH with a viscous term: (1) conventional viscosity formulations generated unphysical forces that hindered rotation, and (2) there was artificial internal energy partitioning within the layered structure, which was due to the standard SPH formulations. To address the first issue, we modified the viscosity formulation. For the second, we adopted Density Independent SPH (DISPH) developed in previous studies to improve behavior at discontinuous surfaces. Additionally, we implemented radiative cooling using an algorithm to define fluid surfaces via the particle method. We also introduced an equation of state accounting for phase transitions. With these modifications, we have refined the SPH method to encompass all necessary physical processes for simulating the evolution of icy moons with internal oceans.

一些冰卫星存在内部海洋的痕迹，如木卫二和土卫二的蒸汽羽流。这意味着在表面冰壳下有一个液态水区域。由于液态水是生命起源的必要条件，因此了解这些内部海洋的发展，特别是其温度分布和演化非常重要。潮汐加热和辐射冷却之间的平衡被认为是维持冰月表面下液态水的关键。我们的目标是利用平滑粒子流体力学（SPH）方法进行三维数值流体计算，模拟冰月内部海洋的潮汐加热。我们在 SPH 的控制方程中加入了粘度和热传导项。然而，在使用带有粘性项的 SPH 计算刚体旋转时，我们遇到了两个问题：(1) 传统的粘性公式会产生阻碍旋转的非物理力；(2) 由于标准的 SPH 公式，分层结构中存在人为的内部能量分配。为了解决第一个问题，我们修改了粘度公式。针对第二个问题，我们采用了之前研究中开发的密度独立 SPH（DISPH），以改善不连续表面的行为。此外，我们还通过粒子法定义流体表面的算法实现了辐射冷却。我们还引入了考虑相变的状态方程。通过这些修改，我们完善了 SPH 方法，使其包含了模拟具有内部海洋的冰卫星演变的所有必要物理过程。

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引用次数: 0