Mkn 180 is the BL Lac object with the spectrum that has been measured through radio and x-ray band to high energy gamma-rays. This object is considered as a potential candidate for the source of high-energy leptonic and/or hadronic cosmic-ray acceleration. Also, it has been proposed to be a GeV–TeV gamma-ray source. The very high energy gamma-rays from Mkn 180 were detected due to the trigger switched on by an optical burst. Mkn 180 was monitored in the optical wave band and in the high and very high energy gamma-rays for a long period and its light curve was obtained. The spectral energy distribution of Mkn 180 blazar was obtained in the wide energy range as well. The spectral energy distributions of blazars consist of two broad peaks. The first, lower frequency peak occurring between radio and soft x-ray energies is due to the synchrotron emissions of relativistic electrons population. Leptonic and hadronic emission mechanisms are considered to describe the second, higher frequency spectrum part between x-ray and VHE gamma-ray energies. The Inverse Compton emissions of the same electrons (synchrotron self-Compton model) or combined with an external Compton mechanism originating from the broad-line region, or the accretion disk are considered in the leptonic scenario. Also, the high energy spectrum part is supposed to be generated due to the processes of photohadronic or hadronuclear interactions of cosmic rays with radiation or matter in the AGN's jet emission region. The multiwavelength observations of Mkn 180 including the GeV–TeV energy data can help to clarify the dominant mechanism of generation of high-energy gamma-ray emission in this object (and whether it can be the source of UHECRs).
{"title":"Mechanisms of High Energy Emission From Mkn 180 BL Lacertae Object","authors":"Vera G. Sinitsyna, Vera Y. Sinitsyna","doi":"10.1002/asna.70018","DOIUrl":"https://doi.org/10.1002/asna.70018","url":null,"abstract":"<div>\u0000 \u0000 <p>Mkn 180 is the BL Lac object with the spectrum that has been measured through radio and x-ray band to high energy gamma-rays. This object is considered as a potential candidate for the source of high-energy leptonic and/or hadronic cosmic-ray acceleration. Also, it has been proposed to be a GeV–TeV gamma-ray source. The very high energy gamma-rays from Mkn 180 were detected due to the trigger switched on by an optical burst. Mkn 180 was monitored in the optical wave band and in the high and very high energy gamma-rays for a long period and its light curve was obtained. The spectral energy distribution of Mkn 180 blazar was obtained in the wide energy range as well. The spectral energy distributions of blazars consist of two broad peaks. The first, lower frequency peak occurring between radio and soft x-ray energies is due to the synchrotron emissions of relativistic electrons population. Leptonic and hadronic emission mechanisms are considered to describe the second, higher frequency spectrum part between x-ray and VHE gamma-ray energies. The Inverse Compton emissions of the same electrons (synchrotron self-Compton model) or combined with an external Compton mechanism originating from the broad-line region, or the accretion disk are considered in the leptonic scenario. Also, the high energy spectrum part is supposed to be generated due to the processes of photohadronic or hadronuclear interactions of cosmic rays with radiation or matter in the AGN's jet emission region. The multiwavelength observations of Mkn 180 including the GeV–TeV energy data can help to clarify the dominant mechanism of generation of high-energy gamma-ray emission in this object (and whether it can be the source of UHECRs).</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 7-8","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145135448","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}
Letchford and White 2025, Paper I, determined the uncertainties in ground-based historic measures of double stars. In this paper, the accuracy of 26,205 ground-based measures of 857 visual double stars, made since 1780, is determined relative to space-based measures based on positions and proper motion from the HIPPARCOS (via ASCC) and Gaia DR3 missions. We determine the accuracy of measures for the epoch of observation, the size of the telescope, the different attached instruments, and the filter applied. We find that the accuracy of the measures is improving with time; however, the typical telescope used for double-star observations has been, and continues to be, relatively small. Modern instrumentation such as speckle interferometry and lucky imaging has advanced the accuracy by a factor of ten over traditional micrometre measurements.
{"title":"Uncertainties in Ground-Based Visual Double Star Measures—II Accuracy of Measures","authors":"Graeme L. White, Roderick R. Letchford","doi":"10.1002/asna.70015","DOIUrl":"https://doi.org/10.1002/asna.70015","url":null,"abstract":"<p>Letchford and White 2025, Paper I, determined the uncertainties in ground-based historic measures of double stars. In this paper, the accuracy of 26,205 ground-based measures of 857 visual double stars, made since <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation>$$ sim $$</annotation>\u0000 </semantics></math>1780, is determined relative to space-based measures based on positions and proper motion from the HIPPARCOS (via ASCC) and <i>Gaia DR3</i> missions. We determine the accuracy of measures for the epoch of observation, the size of the telescope, the different attached instruments, and the filter applied. We find that the accuracy of the measures is improving with time; however, the typical telescope used for double-star observations has been, and continues to be, relatively small. Modern instrumentation such as speckle interferometry and lucky imaging has advanced the accuracy by a factor of ten over traditional micrometre measurements.</p>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 6","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asna.70015","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144843328","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}
Rotational irregularities are one of the prominent observational features that most pulsars exhibit. These glitches, which are sudden increases in spin angular velocity, remains an open problem. In this study, we have investigated the potential role of nontrivial topological defects, specifically in the form of Nambu-Goto type cosmic strings, and its connection to spin irregularities. Such cosmic strings which are one-dimensional topological defects may be formed during various symmetry-breaking and phase transition scenarios and can interact with the neutron stars. In this work, we see that the appearance of such topological defects trapped within the core can lead to the coupling of the string tension with the angular velocity, leading to the abrupt rotational changes observed as pulsar glitches. Further we see, these coupling may generate detectable gravitational waves as a mixture of continuous and burst signals. The evolution of cusps of cosmic strings trapped within neutron stars and the neutron star's mass quadruple moment change due to rotation could produce distinctive gravitational wave signatures, well within the noise cutoff of advLIGO. Our study highlights a potential connection between topological defects, pulsar glitches, and gravitational wave emissions, offering a possible avenue for observationally testing their astrophysical effects.
{"title":"Impact of Topological Structures on Neutron Star Rotation and Their Observational Significance","authors":"Debojoti Kuzur","doi":"10.1002/asna.70017","DOIUrl":"https://doi.org/10.1002/asna.70017","url":null,"abstract":"<div>\u0000 \u0000 <p>Rotational irregularities are one of the prominent observational features that most pulsars exhibit. These glitches, which are sudden increases in spin angular velocity, remains an open problem. In this study, we have investigated the potential role of nontrivial topological defects, specifically in the form of Nambu-Goto type cosmic strings, and its connection to spin irregularities. Such cosmic strings which are one-dimensional topological defects may be formed during various symmetry-breaking and phase transition scenarios and can interact with the neutron stars. In this work, we see that the appearance of such topological defects trapped within the core can lead to the coupling of the string tension with the angular velocity, leading to the abrupt rotational changes observed as pulsar glitches. Further we see, these coupling may generate detectable gravitational waves as a mixture of continuous and burst signals. The evolution of cusps of cosmic strings trapped within neutron stars and the neutron star's mass quadruple moment change due to rotation could produce distinctive gravitational wave signatures, well within the noise cutoff of advLIGO. Our study highlights a potential connection between topological defects, pulsar glitches, and gravitational wave emissions, offering a possible avenue for observationally testing their astrophysical effects.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 9","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145476382","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}
We have conducted investigations of the structure of interstellar medium towards the star 62 Tau using a very high resolving power (R = 170 000) spectrum of ESPRESSO spectrograph. Basic goals of this work are as follows: to search for radial velocity components in the interstellar spectral lines, detectable in the star's spectrum; to measure heliocentric radial velocities (Vr) of the intervening interstellar clouds, to determine Doppler parameter b and the column densities (N) of the atoms and molecules present in the clouds. Using a profile fit procedure we found the components of the atomic and molecular lines with the Vr between 11–18.5 km s. Only two main radial velocity components for every spectral feature could be discerned confidently. Thus, it was found that the interstellar matter on this sightline is mostly concentrated in the interstellar clouds with Vr 15 and 18 km s. The column densities, yielded with the profile fits are in a good agreement with those found earlier by other researchers. The profiles of the interstellar molecular lines (CN, CH and CH
{"title":"Study of the Structure of Interstellar Medium Towards the Star 62 Tau With ESPRESSO Spectrograph","authors":"Arkadii Bondar, Jacek Krełowski","doi":"10.1002/asna.70016","DOIUrl":"https://doi.org/10.1002/asna.70016","url":null,"abstract":"<div>\u0000 \u0000 <p>We have conducted investigations of the structure of interstellar medium towards the star 62 Tau using a very high resolving power (<i>R</i> = <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>λ</mi>\u0000 <mo>/</mo>\u0000 <mrow>\u0000 <mi>δ</mi>\u0000 <mi>λ</mi>\u0000 </mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation>$$ lambda /delta lambda sim $$</annotation>\u0000 </semantics></math>170 000) spectrum of ESPRESSO spectrograph. Basic goals of this work are as follows: to search for radial velocity components in the interstellar spectral lines, detectable in the star's spectrum; to measure heliocentric radial velocities (<i>V</i><sub><i>r</i></sub>) of the intervening interstellar clouds, to determine Doppler parameter b and the column densities (N) of the atoms and molecules present in the clouds. Using a profile fit procedure we found the components of the atomic and molecular lines with the <i>V</i><sub><i>r</i></sub> between <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>≈</mo>\u0000 </mrow>\u0000 <annotation>$$ approx $$</annotation>\u0000 </semantics></math>11–18.5 km s<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mrow>\u0000 <mo> </mo>\u0000 </mrow>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>1</mn>\u0000 </mrow>\u0000 </msup>\u0000 </mrow>\u0000 <annotation>$$ {}^{-1} $$</annotation>\u0000 </semantics></math>. Only two main radial velocity components for every spectral feature could be discerned confidently. Thus, it was found that the interstellar matter on this sightline is mostly concentrated in the interstellar clouds with <i>V</i><sub><i>r</i></sub> <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>≈</mo>\u0000 </mrow>\u0000 <annotation>$$ approx $$</annotation>\u0000 </semantics></math> 15 and 18 km s<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mrow>\u0000 <mo> </mo>\u0000 </mrow>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>1</mn>\u0000 </mrow>\u0000 </msup>\u0000 </mrow>\u0000 <annotation>$$ {}^{-1} $$</annotation>\u0000 </semantics></math>. The column densities, yielded with the profile fits are in a good agreement with those found earlier by other researchers. The profiles of the interstellar molecular lines (CN, CH and CH<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mrow>\u0000 ","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 6","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144843475","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}
4U 2129+47 is classified as a low-mass x-ray binary containing a neutron star. It is actively studied in the optical and x-ray. It was found that this binary exhibits both the outburst and quiescent states. The spectroscopic investigations of the optical counterpart of the neutron star in this binary system showed that the 4U 2129+47 is a hierarchical triple system. X-ray observations showed the evidence for a spatially extended Accretion Disk Corona. This type of objects is considered as a possible source of high energy emission generated due to the interaction between the wind of the neutron star pulsar and accretion disk. Observations of 4U 2129+47 system with SHALON telescope were performed in the period 1999–2011 years. Weak gamma-ray emission from this object was detected with the significance of 11.6σ. An integral flux above > 0.8 GeV was measured. The modulation of detected gamma-ray emission with the orbital period of 5.24 h is found. The hard differential spectrum with the photon index of −1.49 ± 0.13 has been determined. Detected modulation of TeV gamma-ray flux with orbit together with the hard tail of soft x-rays detected with Chandra can be evidence of active accretion and also may point to the generation of emission through the interaction of the wind and accretion stream.
{"title":"Very High Energy Observations of Low-Mass X-Ray Binary 4U 2129+47","authors":"Vera G. Sinitsyna, Vera Y. Sinitsyna","doi":"10.1002/asna.70019","DOIUrl":"https://doi.org/10.1002/asna.70019","url":null,"abstract":"<div>\u0000 \u0000 <p>4U 2129+47 is classified as a low-mass x-ray binary containing a neutron star. It is actively studied in the optical and x-ray. It was found that this binary exhibits both the outburst and quiescent states. The spectroscopic investigations of the optical counterpart of the neutron star in this binary system showed that the 4U 2129+47 is a hierarchical triple system. X-ray observations showed the evidence for a spatially extended Accretion Disk Corona. This type of objects is considered as a possible source of high energy emission generated due to the interaction between the wind of the neutron star pulsar and accretion disk. Observations of 4U 2129+47 system with SHALON telescope were performed in the period 1999–2011 years. Weak gamma-ray emission from this object was detected with the significance of 11.6<i>σ</i>. An integral flux above > 0.8 GeV was measured. The modulation of detected gamma-ray emission with the orbital period of 5.24 h is found. The hard differential spectrum with the photon index of −1.49 ± 0.13 has been determined. Detected modulation of TeV gamma-ray flux with orbit together with the hard tail of soft x-rays detected with Chandra can be evidence of active accretion and also may point to the generation of emission through the interaction of the wind and accretion stream.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 7-8","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145135432","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}
<div> <p><i>XMM-Newton</i> is an ESA space x-ray observatory launched on 11 December 1999, and after 25 years, a study is presented demonstrating that the data of the mission are efficiently used by an engaged and productive community. The total number of refereed papers published between 2000 and 2024 is 8486. These papers have a total of 15,627 different authors, including 3292 unique first authors. The total available science time during this period amounts to 556 Ms (16,894 observations) 87% of which (84% of observations) have been used in at least one refereed publication, excluding primary catalogue papers. Accounting for multiple use, the observation time has been over-used by a factor of up to 15 in dedicated publications and even a factor of up to 30 when including a small fraction of papers classified as survey/catalogue. The speed with which observations are published for the first time peaks around 2 years and is thus longer than the proprietary period for Guest–Observer (GO) observations. A strong secondary peak at 3 years suggests that data not published by the proposing teams are picked up by the community, then also taking about 2 years to be published. The publication rate remains stable at <span></span><math> <semantics> <mrow> <mo>∼</mo> <mn>400</mn> </mrow> <annotation>$$ sim 400 $$</annotation> </semantics></math> refereed articles per year with a small increase in recent years, owed to an increased use of primary <i>XMM-Newton</i> catalogues. 95% of articles focus on specific data using <span></span><math> <semantics> <mrow> <mo><</mo> <mn>49</mn> </mrow> <annotation>$$ <49 $$</annotation> </semantics></math> observations while 99% of articles use less than 239 observations. Since 2010, the annual number of first-time authors has remained relatively constant, equalling the number of last-time authors. This implies that the number of scientists engaged in research utilising <i>XMM-Newton</i> data has remained constant at 4300, of whom 570 are lead (first) authors. A histogram of the activity period demonstrates that 51% of first authors publish for only 1 year, 24% of first authors are active for up to 6 years, and 25% were active for more than 6 years. We further identify a highly productive core community of approximately 120 scientists publishing an <i>XMM-Newton</i> article at least every 2 year as first authors. When all authors are considered, the figures are 40%, 25% and 35%, respectively. The considerable number of time-limited activities may reflect a high level of utilisation during the early stages of a research career, from Master's studies through the PhD and initial postdoctoral years. The trends assessed indicate a vital community with positive perspectives and a continued, active
xmm -牛顿是欧空局于1999年12月11日发射的空间x射线天文台，经过25年的发展，一项研究表明，该任务的数据被一个积极参与和富有成效的社区有效地利用。2000年至2024年间发表的评审论文总数为8486篇。这些论文共有15627位不同的作者，其中包括3292位独特的第一作者。在此期间，总可用科学时间达556毫秒（16,894次观测）87% of which (84% of observations) have been used in at least one refereed publication, excluding primary catalogue papers. Accounting for multiple use, the observation time has been over-used by a factor of up to 15 in dedicated publications and even a factor of up to 30 when including a small fraction of papers classified as survey/catalogue. The speed with which observations are published for the first time peaks around 2 years and is thus longer than the proprietary period for Guest–Observer (GO) observations. A strong secondary peak at 3 years suggests that data not published by the proposing teams are picked up by the community, then also taking about 2 years to be published. The publication rate remains stable at ∼ 400 $$ sim 400 $$ refereed articles per year with a small increase in recent years, owed to an increased use of primary XMM-Newton catalogues. 95% of articles focus on specific data using < 49 $$ <49 $$ observations while 99% of articles use less than 239 observations. Since 2010, the annual number of first-time authors has remained relatively constant, equalling the number of last-time authors. This implies that the number of scientists engaged in research utilising XMM-Newton data has remained constant at 4300, of whom 570 are lead (first) authors. A histogram of the activity period demonstrates that 51% of first authors publish for only 1 year, 24% of first authors are active for up to 6 years, and 25% were active for more than 6 years. We further identify a highly productive core community of approximately 120 scientists publishing an XMM-Newton article at least every 2 year as first authors. When all authors are considered, the figures are 40%, 25% and 35%, respectively. The considerable number of time-limited activities may reflect a high level of utilisation during the early stages of a research career, from Master's studies through the PhD and initial postdoctoral years. The trends assessed indicate a vital community with positive perspectives and a continued, active interest in XMM-Newton for the future.
{"title":"XMM-Newton Publications From 2000 to 2024","authors":"Jan-Uwe Ness, Norbert Schartel, Maria Santos-Lleo","doi":"10.1002/asna.70014","DOIUrl":"https://doi.org/10.1002/asna.70014","url":null,"abstract":"<div>\u0000 \u0000 <p><i>XMM-Newton</i> is an ESA space x-ray observatory launched on 11 December 1999, and after 25 years, a study is presented demonstrating that the data of the mission are efficiently used by an engaged and productive community. The total number of refereed papers published between 2000 and 2024 is 8486. These papers have a total of 15,627 different authors, including 3292 unique first authors. The total available science time during this period amounts to 556 Ms (16,894 observations) 87% of which (84% of observations) have been used in at least one refereed publication, excluding primary catalogue papers. Accounting for multiple use, the observation time has been over-used by a factor of up to 15 in dedicated publications and even a factor of up to 30 when including a small fraction of papers classified as survey/catalogue. The speed with which observations are published for the first time peaks around 2 years and is thus longer than the proprietary period for Guest–Observer (GO) observations. A strong secondary peak at 3 years suggests that data not published by the proposing teams are picked up by the community, then also taking about 2 years to be published. The publication rate remains stable at <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 <mn>400</mn>\u0000 </mrow>\u0000 <annotation>$$ sim 400 $$</annotation>\u0000 </semantics></math> refereed articles per year with a small increase in recent years, owed to an increased use of primary <i>XMM-Newton</i> catalogues. 95% of articles focus on specific data using <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo><</mo>\u0000 <mn>49</mn>\u0000 </mrow>\u0000 <annotation>$$ <49 $$</annotation>\u0000 </semantics></math> observations while 99% of articles use less than 239 observations. Since 2010, the annual number of first-time authors has remained relatively constant, equalling the number of last-time authors. This implies that the number of scientists engaged in research utilising <i>XMM-Newton</i> data has remained constant at 4300, of whom 570 are lead (first) authors. A histogram of the activity period demonstrates that 51% of first authors publish for only 1 year, 24% of first authors are active for up to 6 years, and 25% were active for more than 6 years. We further identify a highly productive core community of approximately 120 scientists publishing an <i>XMM-Newton</i> article at least every 2 year as first authors. When all authors are considered, the figures are 40%, 25% and 35%, respectively. The considerable number of time-limited activities may reflect a high level of utilisation during the early stages of a research career, from Master's studies through the PhD and initial postdoctoral years. The trends assessed indicate a vital community with positive perspectives and a continued, active","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 6","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144843376","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}
The wide variety of topics discussed at the IWARA 2014 workshop in Machu Picchu, Peru, and their relation to a large range of disciplines from archaeology to cosmology is illustrated schematically in this artwork. Names point out authors among the IWARA participants who wrote scientific contributions in the respective field of research. The chart may be taken as a guide to explore the publications in this Special Issue of AN. Some interesting philosophical comments about the science discussed (and not discussed) at the workshop can be found in the Concluding Remarks by J.E. Horvath (e240137).
{"title":"Cover Picture: Astron. Nachr. 3/2025","authors":"J. E. Horvath","doi":"10.1002/asna.70013","DOIUrl":"https://doi.org/10.1002/asna.70013","url":null,"abstract":"<p>The wide variety of topics discussed at the IWARA 2014 workshop in Machu Picchu, Peru, and their relation to a large range of disciplines from archaeology to cosmology is illustrated schematically in this artwork. Names point out authors among the IWARA participants who wrote scientific contributions in the respective field of research. The chart may be taken as a guide to explore the publications in this Special Issue of AN. Some interesting philosophical comments about the science discussed (and not discussed) at the workshop can be found in the Concluding Remarks by J.E. Horvath (e240137).\u0000\u0000 <figure>\u0000 <div><picture>\u0000 <source></source></picture><p></p>\u0000 </div>\u0000 </figure></p>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 3-4","pages":""},"PeriodicalIF":1.1,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asna.70013","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144206590","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}
Tom Richtler, Juan-Pablo Caso, Lilia P. Bassino, Michael Hilker, Neil Nagar
NGC 6411, an isolated elliptical galaxy, appears in the literature with an intermediate age of 3.5 Gyr. Its globular cluster system (GCS), on the other hand, has all the properties of a very old age. The knowledge of the stellar M/L ratio is necessary to evaluate its mass discrepancy. NGC 6411 has a low central surface brightness, which makes it a valuable test object for Modified Newtonian Dynamics (MOND). We reconsider the conflict between age and GCS properties. We perform a stellar population analysis to constrain its baryonic mass and do a kinematical analysis to constrain the total mass. We use data cubes from the CALIFA (Calar Alto Legacy Integral Field Area) survey to investigate the stellar population and measure velocity dispersions of NGC 6411, employing the spectral synthesis codes Starlight and ppxf. The dynamical analysis is based on spherical Jeans models. Using Starlight, an intermediate age of NGC 6411 results only as a Single Stellar Population (SSP) age with a fixed reddening. This seems to be caused by a slightly erroneous continuum slope. ppxf, which does not fit the continuum, gives an SSP age of 12 Gyr. A simple isotropic MOND model reproduces the projected velocity dispersions well. NGC 6411 joins the list of early-type galaxies for which MOND makes a successful prediction. It is special in the sense that due to its low surface brightness, MOND effects become visible at smaller radii than in other elliptical galaxies.
NGC 6411是一个孤立的椭圆星系，在文献中出现的中间年龄为3.5 Gyr。另一方面，它的球状星团系统（GCS）具有非常年老的所有特征。了解恒星的M/L比对于评估其质量差异是必要的。NGC 6411的中心表面亮度较低，这使它成为修正牛顿动力学（MOND）的一个有价值的测试对象。我们重新考虑年龄与GCS性质之间的冲突。我们用恒星总体分析来约束其重子质量，用运动学分析来约束其总质量。我们使用CALIFA （Calar Alto Legacy Integral Field Area）巡天的数据立方体来研究NGC 6411的恒星群，并测量其速度色散，光谱合成代码为Starlight和ppxf。动力学分析基于球面Jeans模型。使用Starlight， NGC 6411的中间年龄只能得到一个固定变红的单一恒星族（SSP）年龄。这似乎是由一个稍微错误的连续体斜率引起的。ppxf不符合连续统，给出SSP年龄为12 Gyr。一个简单的各向同性MOND模型很好地再现了预测的速度色散。NGC 6411加入了MOND成功预测的早期星系名单。它的特殊之处在于，由于其表面亮度较低，MOND效应在比其他椭圆星系更小的半径上可见。
{"title":"MOND and Isolated Elliptical Galaxies—NGC 6411","authors":"Tom Richtler, Juan-Pablo Caso, Lilia P. Bassino, Michael Hilker, Neil Nagar","doi":"10.1002/asna.70011","DOIUrl":"https://doi.org/10.1002/asna.70011","url":null,"abstract":"<div>\u0000 \u0000 <p>NGC 6411, an isolated elliptical galaxy, appears in the literature with an intermediate age of 3.5 Gyr. Its globular cluster system (GCS), on the other hand, has all the properties of a very old age. The knowledge of the stellar <i>M</i>/<i>L</i> ratio is necessary to evaluate its mass discrepancy. NGC 6411 has a low central surface brightness, which makes it a valuable test object for Modified Newtonian Dynamics (MOND). We reconsider the conflict between age and GCS properties. We perform a stellar population analysis to constrain its baryonic mass and do a kinematical analysis to constrain the total mass. We use data cubes from the CALIFA (Calar Alto Legacy Integral Field Area) survey to investigate the stellar population and measure velocity dispersions of NGC 6411, employing the spectral synthesis codes Starlight and ppxf. The dynamical analysis is based on spherical Jeans models. Using Starlight, an intermediate age of NGC 6411 results only as a Single Stellar Population (SSP) age with a fixed reddening. This seems to be caused by a slightly erroneous continuum slope. ppxf, which does not fit the continuum, gives an SSP age of 12 Gyr. A simple isotropic MOND model reproduces the projected velocity dispersions well. NGC 6411 joins the list of early-type galaxies for which MOND makes a successful prediction. It is special in the sense that due to its low surface brightness, MOND effects become visible at smaller radii than in other elliptical galaxies.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 6","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144843575","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}
We explore gravity, a classical extension of general relativity, and evaluate its applicability to compact stars. As a modification of Einstein's theory, gravity serves as a useful framework for investigating gravitational effects in ultra-relativistic regimes where (standard) general relativity may break down, while remaining consistent with it in weak-field limits. In this work, we derive a second-order modified Tolman–Oppenheimer–Volkoff (MTOV) system, consisting of four coupled second-order differential equations, for general gravity. This formulation is applied to static, spherically symmetric strange quark stars modeled using the MIT Bag equation of state. We propose two models, each incorporating a single parameter that governs the deviation from general relativity. The MTOV equations are solved numerically using the Runge–Kutta-Fehlberg method, and the results are compared to those obtained in general relativity. Our findings demonstrate that gravity can yield distinct and physically meaningful modifications to the properties of compact stars. We further examine the contributions of second- and higher-order corrections in the scalar-tensor sector of the gravitational action.
{"title":"Structure of Quark Stars in f(R) Gravity","authors":"Takashi Katayama, Fridolin Weber","doi":"10.1002/asna.70010","DOIUrl":"https://doi.org/10.1002/asna.70010","url":null,"abstract":"<div>\u0000 \u0000 <p>We explore <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>f</mi>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mi>R</mi>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation>$$ f(R) $$</annotation>\u0000 </semantics></math> gravity, a classical extension of general relativity, and evaluate its applicability to compact stars. As a modification of Einstein's theory, <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>f</mi>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mi>R</mi>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation>$$ f(R) $$</annotation>\u0000 </semantics></math> gravity serves as a useful framework for investigating gravitational effects in ultra-relativistic regimes where (standard) general relativity may break down, while remaining consistent with it in weak-field limits. In this work, we derive a second-order modified Tolman–Oppenheimer–Volkoff (MTOV) system, consisting of four coupled second-order differential equations, for general <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>f</mi>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mi>R</mi>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation>$$ f(R) $$</annotation>\u0000 </semantics></math> gravity. This formulation is applied to static, spherically symmetric strange quark stars modeled using the MIT Bag equation of state. We propose two <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>f</mi>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mi>R</mi>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation>$$ f(R) $$</annotation>\u0000 </semantics></math> models, each incorporating a single parameter that governs the deviation from general relativity. The MTOV equations are solved numerically using the Runge–Kutta-Fehlberg method, and the results are compared to those obtained in general relativity. Our findings demonstrate that <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>f</mi>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mi>R</mi>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation>$$ f(R) $$</annotation>\u0000 </semantics></math> gravity can yield distinct and physically meaningful modifications to the properties of compact stars. We further examine the contributions of second- and higher-order corrections in the scalar-tensor sector of the gravitational action.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 7-8","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145135702","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}
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