New Astronomy最新文献

{"title":"Star formation rate estimations of a mid-infrared sample of X-ray selected nearby Active Galactic Nuclei","authors":"Angel Castro ,&nbsp;Takamitsu Miyaji ,&nbsp;Liliana Altamirano-Dévora ,&nbsp;Peter Boorman ,&nbsp;Kohei Ichikawa ,&nbsp;Matthew Malkan ,&nbsp;Héctor Aceves ,&nbsp;Yoshihiro Ueda ,&nbsp;Erika Castillo ,&nbsp;Mauricio Elías-Chavez ,&nbsp;Irene Cruz-González ,&nbsp;Martín Herrera-Endoqui ,&nbsp;Takao Nakagawa","doi":"10.1016/j.newast.2025.102433","DOIUrl":"10.1016/j.newast.2025.102433","url":null,"abstract":"<div><div>We investigate the activity of active galactic nuclei and the circumnuclear star formation properties in a nearby (<span><math><mrow><mi>z</mi><mo>≤</mo><mn>0</mn><mo>.</mo><mn>1</mn></mrow></math></span>) sample of 125 hard X-ray (14–195 keV) selected active Galactic Nuclei (AGN) from the <em>Swift</em>/BAT 70-month survey catalogue. Using the 11.3 <span><math><mrow><mi>μ</mi><mi>m</mi></mrow></math></span> polycyclic aromatic hydrocarbon (PAH) emission feature measured with the <em>Spitzer</em>/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 (<span><math><msub><mrow><mi>L</mi></mrow><mrow><mi>X</mi></mrow></msub></math></span>) 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 <em>AKARI</em>/IRC measurements of the 3.3 <span><math><mrow><mi>μ</mi><mi>m</mi></mrow></math></span> 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.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"121 ","pages":"Article 102433"},"PeriodicalIF":1.9,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144221028","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}

{"title":"Mapping the reddening plane in the Galactic disk through interstellar extinction of open clusters","authors":"Y.C. Joshi","doi":"10.1016/j.newast.2025.102425","DOIUrl":"10.1016/j.newast.2025.102425","url":null,"abstract":"<div><div>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 (<span><math><mrow><mrow><mo>|</mo><mi>b</mi><mo>|</mo></mrow><mo>≤</mo><mn>6</mn><mo>°</mo></mrow></math></span>), 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 <span><math><mrow><mn>42</mn><mo>°</mo></mrow></math></span> and <span><math><mrow><mn>222</mn><mo>°</mo></mrow></math></span>, 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 <span><math><mrow><mn>15</mn><mo>.</mo><mn>7</mn><mo>±</mo><mn>7</mn><mo>.</mo><mn>3</mn></mrow></math></span> pc above the reddening plane. The scale height of the open clusters from the reddening plane is estimated to be <span><math><mrow><msub><mrow><mi>z</mi></mrow><mrow><mi>h</mi></mrow></msub><mo>=</mo><mn>87</mn><mo>.</mo><mn>3</mn><mo>±</mo><mn>1</mn><mo>.</mo><mn>8</mn></mrow></math></span> 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 <span><math><mrow><mn>201</mn><mo>±</mo><mn>20</mn></mrow></math></span> 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.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"121 ","pages":"Article 102425"},"PeriodicalIF":1.9,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144221029","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}

{"title":"A study on the formation of field, binary or multiple stars: A 3D approach through dynamical system","authors":"Ashok Mondal ,&nbsp;Tanuka Chattopadhyay","doi":"10.1016/j.newast.2025.102424","DOIUrl":"10.1016/j.newast.2025.102424","url":null,"abstract":"<div><div>We have studied a three-dimensional model using the concept of double-well potential to find out what kind of stars can be formed from filamentary molecular clouds depending on their density. We have shown the effect of both rotation and magnetic fields in the process of star formation. It is found that thin filamentary MCs can lead to the formation of field stars, and this occurs even in a rapidly rotating cloud or in a magnetized rotating cloud. In absence of a magnetic field, binary stars form from a moderately dense structure, whereas in presence of a magnetic field isolated field stars may also form. For a moderately high dense structure, the nature of stars depends on the combined effect of rotation and magnetic field strength. High dense and compressed filamentary MCs are favorable to form stellar associations or more massive star clusters.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"120 ","pages":"Article 102424"},"PeriodicalIF":1.9,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144184259","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}

{"title":"Potential optical astronomical sites in less developed countries","authors":"Pedro Augusto","doi":"10.1016/j.newast.2025.102434","DOIUrl":"10.1016/j.newast.2025.102434","url":null,"abstract":"<div><div>A “suitability index for astronomical sites” (SIAS) has been proposed to more easily select the best sites in the world as regards cloud cover, elevation, and artificial light. The SIAS brings new and great potential for countries with few resources, typically less developed countries (LDCs). However, it lacks crucial quantitative astronomical <em>seeing</em> information, quite expensive to gather (for this, we have developed a new technique and portable instrument to lower the costs of measuring the seeing). Good seeing exists on the up-wind edge of a mountain top with a greater than 1:3 slope angle towards laminar flow dominating winds (coastal sites or small islands). By inspecting with Google Earth the terrain and surrounding area of each SIAS-selected candidate site as regards the mountain height and slopes, the distance from the nearest sea/lake, and its mountainous neighborhood, we have shortlisted the best 13 sites for optical astronomy in eight LDCs.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"121 ","pages":"Article 102434"},"PeriodicalIF":1.9,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144204529","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}

{"title":"On the logarithmic parameterization for the deceleration parameter in f(Q,C)-gravity","authors":"Andronikos Paliathanasis","doi":"10.1016/j.newast.2025.102426","DOIUrl":"10.1016/j.newast.2025.102426","url":null,"abstract":"<div><div>We show that the gravitational Lagrangian introduced in Bhoyar and Ingole, (2025) is nothing else than that of the power-law <span><math><mrow><mi>f</mi><mfenced><mrow><mi>Q</mi></mrow></mfenced><mo>=</mo><msup><mrow><mi>Q</mi></mrow><mrow><mi>n</mi></mrow></msup></mrow></math></span> theory and the boundary term <span><math><mi>C</mi></math></span> plays no role in this study.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"120 ","pages":"Article 102426"},"PeriodicalIF":1.9,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144146963","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}

{"title":"Matter power spectrum in a power-law f(G) gravity","authors":"Albert Munyeshyaka ,&nbsp;Praveen Kumar Dhankar ,&nbsp;Joseph Ntahompagaze","doi":"10.1016/j.newast.2025.102423","DOIUrl":"10.1016/j.newast.2025.102423","url":null,"abstract":"<div><div>Cosmological models based on <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span> gravity are efficient in fitting different observational datasets at both background and perturbation levels. This motivates the current study to take into account dynamical system analysis to investigate the matter power spectrum within the framework of modified Gauss–Bonnet gravity. After defining the dimensionless dynamical system variables for a power-law <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span> model, We derive the full system of equations governing the energy density perturbations for both matter and Gauss–Bonnet fluids using the <span><math><mrow><mn>1</mn><mo>+</mo><mn>3</mn></mrow></math></span> covariant formalism. After solving the energy density perturbation equations, we compute the matter power spectrum. The importance of studying first order perturbations for the defined <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span> model and the relevance of different initial conditions in computing the matter power spectrum are also stressed. It is reported that matter power spectrum for <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span> gravity, for a particular functional form of <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span> model considered is not scale invariant as the case for General Relativity.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"120 ","pages":"Article 102423"},"PeriodicalIF":1.9,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143941885","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}

{"title":"Lightcurves of stars in the Chamaeleon I association","authors":"K. Neumannová ,&nbsp;L. Kueß ,&nbsp;E. Paunzen ,&nbsp;K. Bernhard","doi":"10.1016/j.newast.2025.102409","DOIUrl":"10.1016/j.newast.2025.102409","url":null,"abstract":"<div><div>Star-forming regions are essential for studying very young stellar objects of various masses. They still contain a significant amount of dust and gas. We present a study of light curves of stars in the field of the Chamaeleon I association. We use automatic spectral classification with MKCLASS to identify the spectral types of the stars in the field with a light curve from the NEOWISE and Gaia surveys. The light curves are analysed using the software Peranso and astropy. We also used VSX to identify the variability type. Based on astrometry, we have identified 92 stars, 73 of which are members of the association. We received light curves for 55 stars from the Gaia survey and for 69 stars from the ALLWISE/NEOWISE survey. For 28 of them, it was possible to determine the types of variables, mostly T Tauri and Orion variables. The spectral types of the members are mostly cooler M-type stars, with one being a possible chemically peculiar (CP) star. The non-members associated with light curve measurements include spectral types A-G with one CP candidate.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"120 ","pages":"Article 102409"},"PeriodicalIF":1.9,"publicationDate":"2025-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143948099","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}

{"title":"Universal relationships for neutron stars from perturbative approach","authors":"Debasis Atta ,&nbsp;Vinay Singh ,&nbsp;D.N. Basu","doi":"10.1016/j.newast.2025.102422","DOIUrl":"10.1016/j.newast.2025.102422","url":null,"abstract":"<div><div>The universal relationships for compact stars have been investigated employing perturbative approach using canonical (APR) and Brussels–Montreal Skyrme (BSk22, BSk24, BSk26) equations of state describing hadronic matter of neutron stars. The neutron star matter has been considered to be <span><math><mi>β</mi></math></span>-equilibrated neutron–proton–electron–muon matter at the core with a rigid crust. The multipole moments of a slowly rotating neutron star characterize its external gravitational field. These variables are dependent on the interior structure of the neutron star described by the equation of state of the neutron star matter. The properties of neutron stars, such as the mass, the radius, the dimensionless moment of inertia, the compactness, the Love number, the dimensionless tidal deformability and the dimensionless quadrupole moment have been calculated and relations among these quantities have been explored. It is found that most of these relations do not depend sensitively on the details of the internal structure of neutron stars. Such universality implies that the measurement of a single quantity appearing in a universal relation would automatically provide information about the others, notwithstanding the fact that those may not be accessible observationally. Such relations can be utilized to assess the deformability of compact stars by measuring their moment of inertia, to evaluate spin in binary inspirals by resolving degeneracies in gravitational wave detection or to examine General Relativity in a manner that is not reliant on nuclear structure.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"120 ","pages":"Article 102422"},"PeriodicalIF":1.9,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143936934","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}

{"title":"Diagnozing star formation in the Chamaeleon–Musca dark cloud complex","authors":"H.Y. Chen ,&nbsp;W.P. Chen","doi":"10.1016/j.newast.2025.102421","DOIUrl":"10.1016/j.newast.2025.102421","url":null,"abstract":"<div><div>We present a comprehensive young stellar census of the Chamaeleon–Musca dark-cloud complex. Searching in a <span><math><mrow><mn>12</mn><mo>°</mo><mo>×</mo><mn>12</mn><mo>°</mo></mrow></math></span> sky area using Gaia DR3 data for astrometric membership, aided by 2MASS and ALLWISE infrared colors for disk-bearing objects, we have found not only members known to be associated with main clouds, but also inter-cloud candidates discovered for the first time. We confirm that Cha I is active in starbirth with more than 200 members. Cha II harbors some 50 members, among which three are projected in northern Cha III, which itself lacks any star-forming activity. The subcluster Cha I South is at an average distance of <span><math><mo>∼</mo></math></span>189 pc, slightly nearer than Cha I North at <span><math><mo>∼</mo></math></span>192 pc, whereas Cha II is farther at <span><math><mo>∼</mo></math></span>198 pc, forming a distance sequence. The isochrone fitting indicates a consistent age of about 3 Myr for Cha I and Cha II, suggesting coeval star formation. Our work confirms the Musca filament with the paucity of fully grown young stars. Serendipitously, in the foreground (<span><math><mo>∼</mo></math></span>110 pc), some members of <span><math><mi>ϵ</mi></math></span> Cha or LCC associations are projected in our studied field; they are more evolved pre-main sequence objects or dwarfs with an age spread of 5-20 Myr. Also detected in our data is a part of the cluster UPK<!--> <!-->569 older (<span><math><mo>∼</mo></math></span>30 My) and farther (<span><math><mo>∼</mo></math></span>250 pc) than Chamaeleon clouds. An analysis of two separate clouds some 10 deg to the south-east, Cha-East I and Cha-East II, uncovers no young stars, lending support that Cha I and Cha II mark the end of the sequence of the latest episode of triggered star formation by the Sco-Cen OB association.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"120 ","pages":"Article 102421"},"PeriodicalIF":1.9,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143923423","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}

{"title":"How accurate are current 56Ni mass estimates in Type Ia Supernovae?","authors":"Jagriti Gaba ,&nbsp;Rahul Kumar Thakur ,&nbsp;Naresh Sharma ,&nbsp;Dinkar Verma ,&nbsp;Shashikant Gupta","doi":"10.1016/j.newast.2025.102411","DOIUrl":"10.1016/j.newast.2025.102411","url":null,"abstract":"<div><div>The diversity of type Ia supernovae (SNe Ia) has become increasingly apparent with the rapid growth in observational data. Understanding the explosion mechanism of SNe Ia is crucial for their cosmological calibration and for advancing our knowledge of stellar physics. The estimation of ⁵⁶Ni mass produced in these events is key to elucidating their explosion mechanism. This study compares two methods of ⁵⁶Ni mass estimation. We first examine the relationship between peak luminosity and the second maximum in near-infrared (NIR) bands using observations of 18 nearby SNe Ia. Based on this relationship, we estimate the Ni mass for a set of nine well-observed SNe Ia using the Arnett rule. Additionally, we estimate the ⁵⁶Ni mass using bolometric light curves of these SNe through energy conservation arguments. A comparison of these two estimation methods using Student’s t-test reveals no statistically significant differences between the estimates. This finding suggests that both methods provide robust estimates of Ni mass in SNe Ia.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"120 ","pages":"Article 102411"},"PeriodicalIF":1.9,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144167722","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}