New Astronomy最新文献

英文中文

The young stellar cluster towards IRAS 03523+5343

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

New Astronomy

Pub Date : 2025-03-17 DOI: 10.1016/j.newast.2025.102405

João L. Yun , Pedro M. Martins , Gorka Zubiri-Elso , Anlaug Amanda Djupvik

We present a study of the star formation occurring in the most active region of a molecular cloud in the second quadrant of the (outer) Galaxy towards IRAS 03523+5343. Near-infrared

J H K_{S}

images and

K

-band spectroscopy were obtained with NOTCam at the Nordic Optical Telescope at the Roque de Los Muchachos Observatory. Mid-infrared WISE satellite images and submm JCMT/SCUBA-2 catalogue sources were also explored. In addition, millimetre line CS spectra were obtained with the Yebes 40 m telescope.

Within the region of the molecular cloud covered by our CS

(J = 1 - 0)

maps, the line is strong and extends over all the mapped region of

3 . 7^{'} \times 3 . 7^{'}

. This high-density molecular gas defines a molecular core exhibiting an angular size FWHM of about

1^{'}

(0.7 pc at 2.4 kpc distance). We estimate a lower limit to the mass of the molecular gas in this region to be about 995

M_{⊙}

. A SCUBA-2 core was detected with an estimated total mass of 250

M_{⊙}

We identify a young stellar cluster with a few hundred sources with colours compatible to YSOs at the location of a strong enhancement of the stellar density coincident with the IRAS position. The main counterpart of the IRAS source is a very red and bright source with radio jets likely to be a high-mass young stellar object. A second bright source is a Herbig Be candidate source displaying a blue nebula with a morphology that suggests the dissipation of a collimated flow.

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引用次数: 0

CCD photometric studies of two Primitive C-type main-belt asteroids: (51) Nemausa and (52) Europa

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

New Astronomy

Pub Date : 2025-03-15 DOI: 10.1016/j.newast.2025.102391

Shuang Wang, Yuangui Yang, Huiyu Yuan, Ligang Yu

We present new CCD photometry for primitive C-type main-belt asteroids (51) Nemausa and (52) Europa performed on several nights of 2016, by using the 60-cm telescope at Xinglong station of NAOC. From our new data, the rotation periods are determined as 7.784840 h for (51) Nemausa and 5.629960 h for (52) Europa. Based on the convex inversion method, the pole ambiguity was removed, and we refined pole directions and triaxial ratios as follows, (168 °,

- 6 0^{\circ}

) with

a / b = 1.09

and

b / c = 1.03

for (51) Nemausa, and a pole is derived as (256°, 32°) with

a / b = 1.04

and

b / c = 1.33

for (52) Europa. From the parameters of 49 asteroids, a statistic study was carried out. All these results will help us to understand the physical properties of pristine small objects in the solar system.

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引用次数: 0

Anisotropic compact stellar models under the condition of zero complexity

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

New Astronomy

Pub Date : 2025-03-14 DOI: 10.1016/j.newast.2025.102393

Shyam Das , Saibal Ray , Amit Das , Shyamal Kumar Pal

In this article, we introduce a new exact solution of the Einstein field equations that characterizes static, spherically symmetric anisotropic compact stars. In our approach the solution of the system of field equations have been obtained under the constraint of vanishing complexity, in addition to specifying the metric potential corresponding to the

g_{r r}

component. The class of generalized solutions has been smoothly matched with the Schwarzschild solutions describing the exterior across the boundary. The model parameters are fixed by using this matching conditions and additionally from the condition of the vanishing of the radial pressure at the surface. We have employed recent measurements of the mass and radius from the observed pulsars to validate and justify the physical applicability of our model.

引用次数: 0

The role of Finsler-Randers geometry in shaping anisotropic metrics and thermodynamic properties in black holes theory

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

New Astronomy

Pub Date : 2025-03-13 DOI: 10.1016/j.newast.2025.102404

J Praveen, S K Narasimhamurthy

In this research paper, we delve into the study of black hole (BH) structure within the context of Finsler geometry, a novel approach not previously explored by other researchers. We focused on developing the Finsler-Randers metric tensor for black holes, with the aid of the Barthel connection along with the osculating Riemannian method. This newly derived metric demonstrates significant departures from the conventional black hole metrics found in General Relativity (GR) by the presence of Finslerian term

η

, thereby shedding new light on the geometry and nature of black holes. To comprehensively understand the characteristics of black holes, we calculated the metric components under both vacuum and non-vacuum conditions. Our findings indicate that the metric structure aligns well with the known Riemannian limits, reinforcing the compatibility of our model with established theories. Moreover, we extended our analysis to include the thermodynamics of black holes in a Finslerian framework in brief. The results from this exploration affirm that the fundamental laws of black hole thermodynamics remain valid, reinforcing the viability and consistency of our Finslerian model. This study not only contributes to our understanding of black hole physics but also opens new avenues for further research in the realm of Finsler geometry and its implications for astrophysics.

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引用次数: 0

Evolution of neutron stars in wide eccentric low-mass binary systems

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

New Astronomy

Pub Date : 2025-03-13 DOI: 10.1016/j.newast.2025.102401

Marina Afonina , Sergei Popov

Precise astrometric measurement with Gaia satellite resulted in the discovery of tens of wide binary systems consisting of a Sun-like star and an invisible component. The latter can be a white dwarf, a neutron star, or a black hole. In this paper, we model magneto-rotational evolution of neutron stars in wide low-mass binaries accounting for the orbital eccentricity. We aim to calculate when neutron stars in such systems can start to accrete matter from the stellar wind of the companion. We show that the transition from the ejector to the propeller stage occurs earlier in more eccentric systems, thus increasing the time that neutron stars can spend accreting matter. Our calculations show that in the case of efficient spin-down at the propeller stage, a neutron star in an eccentric orbit with

e ≳ 0.6

and a standard magnetic field

B = 1 0^{12}

G can start accreting within a few Gyr. For neutron stars with

B = 1 0^{13}

G the onset of accretion occurs earlier regardless of the orbital eccentricity. Otherwise, with a lower spin-down rate, such a neutron star will remain at the propeller stage for most of its life.

利用盖亚卫星进行的精确天体测量发现了数十个由一颗类太阳恒星和一个不可见成分组成的宽双星系统。后者可以是白矮星、中子星或黑洞。在本文中，我们模拟了低质量宽双星中中子星的磁旋转演化，并考虑了轨道偏心率。我们旨在计算这类系统中的中子星何时开始从伴星的恒星风中吸积物质。我们的研究表明，在偏心率较高的系统中，从喷射器阶段向推进器阶段的过渡发生得更早，从而增加了中子星吸积物质的时间。我们的计算显示，在螺旋桨阶段有效自旋下降的情况下，一颗位于偏心轨道上、e≳0.6、标准磁场 B=1012 G 的中子星可以在几个 Gyr 内开始增殖。对于 B=1013 G 的中子星，无论轨道偏心率如何，开始增殖的时间都会提前。否则，由于自旋下降率较低，这样的中子星在其生命的大部分时间里都将停留在螺旋桨阶段。

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引用次数: 0

Parameterized Deceleration in f(Q,C) Gravity: A Logarithmic Approach

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

New Astronomy

Pub Date : 2025-03-01 DOI: 10.1016/j.newast.2025.102386

S.R. Bhoyar, Yash B. Ingole

This study explores a novel logarithmic parameterization of the deceleration parameter within the

f (Q, C)

gravity framework, incorporating a nonlinear functional form

f (Q, C) = γ_{1} Q^{n} + γ_{2} C

, where

Q

and

C

denote the nonmetricity scalar and boundary term respectively and

n > 1

. This approach provides a distinctive perspective on the accelerated expansion of the universe without resorting to exotic fields. Using Observational Hubble Data (

O H D

) measurement and the

P a n t h e o n + S H 0 E S

Type Ia supernovae dataset, the model parameters were restricted by a

χ^{2}

minimization technique. The analysis reveals a transition from deceleration to acceleration in the expansion history of the universe, with transition redshifts

z_{t} \approx 0.98

(

O H D

) and

z_{t} \approx 0.76

(

P a n t h e o n + S H 0 E S

). The model demonstrates consistency with observations, offering insights into the dynamics of dark energy and alternative gravity theories while effectively modeling cosmic evolution across epochs.

引用次数: 0

Impact on orbital period of X-ray binary systems attached to a cosmic string 附在宇宙弦上的 X 射线双星系统对轨道周期的影响

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

New Astronomy

Pub Date : 2025-02-28 DOI: 10.1016/j.newast.2025.102378

Ishan Swamy, Deobrat Singh

Cosmic strings attached to rotating black holes extract its rotational energy, resulting in a mass loss and reduced spin. In this paper we discuss the proposed methods to detect these phenomena and present a novel methodology based on existing literature, by considering a Low Mass X-ray binary system. We investigate the impact of a cosmic string interacting with a black hole in an X-ray binary system and attempt to explain the observations of unexpected orbital period changes in such systems by proposing mass loss by cosmic strings to be a potential cause. For a period change of order

1 0^{- 10}

, the string tension is

\sim 1 0^{- 17}

, lying in the predicted range for cosmic string tension. An analysis of multiple low mass X-ray binary systems is carried out and it is shown that a significant and observable change occurs for a string tension

\sim 1 0^{- 11}

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引用次数: 0

Thermal conduction and thermal-driven winds in magnetized viscous accretion disk dynamics

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

New Astronomy

Pub Date : 2025-02-28 DOI: 10.1016/j.newast.2025.102377

Biplob Sarkar , Indu Kalpa Dihingia , Ranjeev Misra

This paper investigates the effects of saturated thermal conduction (TC) and thermal-driven winds (TDWs) on magnetized advection-dominated accretion onto a rotating black hole (BH). We incorporate dissipative processes in the magnetized accretion flow and expect the accretion disk to be threaded by predominantly toroidal and turbulent magnetic fields. We solve the magnetohydrodynamics equations and construct a self-consistent steady model of the magnetized accretion flow surrounding a rotating BH, which includes TC and TDWs. We seek global accretion solutions spanning from the BH horizon to a large distance and analyze the solution’s characteristics as a function of dissipation parameters. Accretion solutions with multiple critical points may exhibit shock waves if they meet the standing shock criteria. We found steady, global transonic, and shocked accretion solutions around the rotating BH. In particular, the wind parameter (

m

) and the saturated conduction parameter (

Φ_{s}

) significantly influence the dynamical behavior of shocks. The shock location moves away from the BH horizon as

Φ_{s}

and

m

increase, assuming fixed conditions at the disk’s outer edge. Our formalism explains the declining phase of BH outbursts, characterized by a monotonic decrease in QPO frequency as the burst decays. Based on our findings, we conclude that the combined effect of

Φ_{s}

and

m

parameters substantially alters the steady shock specific energy vs angular momentum parameter space and also modifies the corresponding post-shock luminosity vs QPO frequency parameter space. We propose, based on our theoretical model, that the

Φ_{s}

and

m

parameters may significantly influence the evolution of the BH outbursts.

{"title":"Thermal conduction and thermal-driven winds in magnetized viscous accretion disk dynamics","authors":"Biplob Sarkar , Indu Kalpa Dihingia , Ranjeev Misra","doi":"10.1016/j.newast.2025.102377","DOIUrl":"10.1016/j.newast.2025.102377","url":null,"abstract":"<div><div>This paper investigates the effects of saturated thermal conduction (TC) and thermal-driven winds (TDWs) on magnetized advection-dominated accretion onto a rotating black hole (BH). We incorporate dissipative processes in the magnetized accretion flow and expect the accretion disk to be threaded by predominantly toroidal and turbulent magnetic fields. We solve the magnetohydrodynamics equations and construct a self-consistent steady model of the magnetized accretion flow surrounding a rotating BH, which includes TC and TDWs. We seek global accretion solutions spanning from the BH horizon to a large distance and analyze the solution’s characteristics as a function of dissipation parameters. Accretion solutions with multiple critical points may exhibit shock waves if they meet the standing shock criteria. We found steady, global transonic, and shocked accretion solutions around the rotating BH. In particular, the wind parameter (<span><math><mi>m</mi></math></span>) and the saturated conduction parameter (<span><math><msub><mrow><mi>Φ</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span>) significantly influence the dynamical behavior of shocks. The shock location moves away from the BH horizon as <span><math><msub><mrow><mi>Φ</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span> and <span><math><mi>m</mi></math></span> increase, assuming fixed conditions at the disk’s outer edge. Our formalism explains the declining phase of BH outbursts, characterized by a monotonic decrease in QPO frequency as the burst decays. Based on our findings, we conclude that the combined effect of <span><math><msub><mrow><mi>Φ</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span> and <span><math><mi>m</mi></math></span> parameters substantially alters the steady shock specific energy vs angular momentum parameter space and also modifies the corresponding post-shock luminosity vs QPO frequency parameter space. We propose, based on our theoretical model, that the <span><math><msub><mrow><mi>Φ</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span> and <span><math><mi>m</mi></math></span> parameters may significantly influence the evolution of the BH outbursts.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"118 ","pages":"Article 102377"},"PeriodicalIF":1.9,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143549349","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 discrepant long-term activities of the polars BY Camelopardalis and AR Ursae Majoris

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

New Astronomy

Pub Date : 2025-02-23 DOI: 10.1016/j.newast.2025.102375

Vojtěch Šimon

Polars are cataclysmic variables with strongly magnetized white dwarfs (WDs). This analysis of the long-term optical activity of two polars (BY Cam and AR UMa) used the light curves of CCD data from the ZTF and CRTS and photographic data from the DASCH databases. These two polars display remarkably discrepant long-term activities. The high-state activity dominated BY Cam, except for a short and shallow low-state episode. A fit to BY Cam’s light curve shows long-term brightness changes in the high state. We ascribe the variable profiles of the histograms of the residuals of this fit (1-year bins) to the changes in the dominance of the individual accretion modes and accreting regions on the WD with time (hundreds of days). The high-state episodes (no matter how long and bright) of AR UMa occurred from a relatively stable low-state brightness level. The superorbital changes of AR UMa dominated in the high states. Bursts of mass transfer from the donor are likely to contribute to the short high-state episodes.

引用次数: 0

Investigation of the correlation between geomagnetic storms and cosmic ray intensity as well as cosmic ray intensity variation with solar wind parameters during three consecutive solar cycles 23, 24, and 25

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

New Astronomy

Pub Date : 2025-02-23 DOI: 10.1016/j.newast.2025.102387

Nisha Kohli , Suman Garia , Deepak Pandey , Meena Pokharia , Megha Agari

A systematic correlation study has been performed in order to establish a significant association between CRI (cosmic ray intensity) and the following parameters: flow pressure, solar wind speed, plasma proton density, solar wind plasma temperature, and IMF (interplanetary magnetic field) for solar cycles 23 and 24, as well as the most recent solar cycle 25. To do this, we used a Chree analysis by superposed-epoch technique to investigate the link between hour-to-hour changes of CRI and the above-mentioned parameters. We found that there is a strong link between CRI and solar wind speed when compared to IMF. This suggests that solar wind speed is a more capable parameter than IMF to cause a decline in CRI. It was observed that for all three solar cycles, there is an inverse correlation between IMF and solar wind speed and a positive correlation between Dst and CRI. We found that solar wind plasma temperature, flow pressure, and plasma proton density have weak correlations with CRI, making them ineffective for CRs (cosmic rays). For all three solar cycles' intense and severe storms, we have discovered a very interesting and adequate result: maximum decline in CRI is observed on the days of minimal Dst (0–11hrs), IMF maximum (0–19hrs), and peak solar wind speed (0–15hrs). We discovered that the instantaneous modulation of CRI is caused by both the solar wind speed and the IMF. Notable behavior was displayed in the years 1999, 2000, 2004, 2014, 2016 2018, and 2023.

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