A. Biviano, F. Durret, D. Gerbal, O. Fèvre, C. Lobo, A. Mazure, É. Slezak
We have applied a wavelet transform analysis on ROSAT images and on an optical catalouge of the Coma cluster of galaxies. The comparison of these two sets of images allows us a detection of X‐ray emitting galaxies as well as particular emitting regions.
{"title":"X-ray and Optical Wavelet Maps in the Central Region of Coma","authors":"A. Biviano, F. Durret, D. Gerbal, O. Fèvre, C. Lobo, A. Mazure, É. Slezak","doi":"10.1063/1.48336","DOIUrl":"https://doi.org/10.1063/1.48336","url":null,"abstract":"We have applied a wavelet transform analysis on ROSAT images and on an optical catalouge of the Coma cluster of galaxies. The comparison of these two sets of images allows us a detection of X‐ray emitting galaxies as well as particular emitting regions.","PeriodicalId":80579,"journal":{"name":"Astrophysical letters & communications","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1996-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.48336","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58775396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Preface 1. Introduction 2. Symmetries and conservation laws 3. Why a probabilistic description of turbulence? 4. Probabilistic tools: a survey 5. Two experimental laws of fully developed turbulence 6. The Kolmogorov 1941 theory 7. Kolmogorov and Landau: the lack of universality 8. Phenomenology of turbulence in the sense of Kolmogorov 1941 9. Intermittency 10. Further reading: a guided tour References Author index Subject index.
{"title":"Turbulence: The Legacy of A. N. Kolmogorov","authors":"U. Frisch","doi":"10.1063/1.881555","DOIUrl":"https://doi.org/10.1063/1.881555","url":null,"abstract":"Preface 1. Introduction 2. Symmetries and conservation laws 3. Why a probabilistic description of turbulence? 4. Probabilistic tools: a survey 5. Two experimental laws of fully developed turbulence 6. The Kolmogorov 1941 theory 7. Kolmogorov and Landau: the lack of universality 8. Phenomenology of turbulence in the sense of Kolmogorov 1941 9. Intermittency 10. Further reading: a guided tour References Author index Subject index.","PeriodicalId":80579,"journal":{"name":"Astrophysical letters & communications","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1996-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.881555","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59099351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1996-01-01DOI: 10.1007/978-94-009-1726-2_16
M. Verheijen
{"title":"AN HI STUDY OF URSA-MAJOR SPIRALS","authors":"M. Verheijen","doi":"10.1007/978-94-009-1726-2_16","DOIUrl":"https://doi.org/10.1007/978-94-009-1726-2_16","url":null,"abstract":"","PeriodicalId":80579,"journal":{"name":"Astrophysical letters & communications","volume":"31 1","pages":"349-352"},"PeriodicalIF":0.0,"publicationDate":"1996-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51510850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-12-01DOI: 10.1080/03091929508229066
A. Ferriz-Mas, M. Schüssler
Abstract Motivated by the problems of magnetic flux storage and dynamo action in stars with convection zones, we study the equilibrium and stability of magnetic flux tubes under the influence of differential rotation and stratification. The formalism developed in the first paper in this series is applied to axisymmetric, toroidal flux tubes (flux rings) lying in planes parallel to the equator at an arbitrary latitude. We assume mechanical force equilibrium, which requires neutral buoyancy of the flux tube and a longitudinal internal flow in the direction of stellar rotation. Stability against isentropic perturbations is investigated by considering both axisymmetric and non-axisymmetric, three-dimensional displacements of the equilibrium configuration. For axisymmetric modes, we find qualitative differences between the stability criteria for flux tubes within and outside the equatorial plane, where instability is generally easier to excite and overstable modes appear. In the case of non-axisymmetric pertur...
{"title":"Instabilities of Magnetic Flux Tubes in a Stellar Convection Zone","authors":"A. Ferriz-Mas, M. Schüssler","doi":"10.1080/03091929508229066","DOIUrl":"https://doi.org/10.1080/03091929508229066","url":null,"abstract":"Abstract Motivated by the problems of magnetic flux storage and dynamo action in stars with convection zones, we study the equilibrium and stability of magnetic flux tubes under the influence of differential rotation and stratification. The formalism developed in the first paper in this series is applied to axisymmetric, toroidal flux tubes (flux rings) lying in planes parallel to the equator at an arbitrary latitude. We assume mechanical force equilibrium, which requires neutral buoyancy of the flux tube and a longitudinal internal flow in the direction of stellar rotation. Stability against isentropic perturbations is investigated by considering both axisymmetric and non-axisymmetric, three-dimensional displacements of the equilibrium configuration. For axisymmetric modes, we find qualitative differences between the stability criteria for flux tubes within and outside the equatorial plane, where instability is generally easier to excite and overstable modes appear. In the case of non-axisymmetric pertur...","PeriodicalId":80579,"journal":{"name":"Astrophysical letters & communications","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1995-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/03091929508229066","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59775768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Coronal Loop Oscillations Driven by Footpoint Motions: Analytical Results for a Model Problem","authors":"D. Berghmans, P. Bruyne","doi":"10.1086/176410","DOIUrl":"https://doi.org/10.1086/176410","url":null,"abstract":"","PeriodicalId":80579,"journal":{"name":"Astrophysical letters & communications","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1995-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60533406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
According to many schemes for galaxy formation, galaxy morphology should depend strongly on the environment in which a galaxy resides and, especially, in which it was formed. Therefore, in pairs of galaxies one expects to find members of similar morphological type. However, morphological studies of paired galaxies show two different categories: pairs formed by galaxies with similar morphology (EE and SS) and pairs of mixed morphology (ES), where E represents early--type galaxies and S represents late--types. Actually a significant percentage of pairs in reasonably complete samples of binary galaxies (e.g. Catalog of Isolated Pairs of Galaxies by Karachentsev) are of mixed type. Moreover, the distribution of radial velocity differences between components of mixed pairs is similar to that for concordant type (especially SS) pairs. This is further support for the contention that most are physical binaries. We used imaging, spectroscopy and stellar population synthesis to study the interaction effects in 5 mixed pairs of galaxies (AM0327-285, AM1806-852, AM1907-504, AM2016-330, AM2055-492). The present pair sample originated from a sample of 126 candidate mixed pairs that were found during a visual search on the ESO sky surveys. An isolation criterion was employed that required the distance to the nearest neighbor (with major axis diameter ≥ the diameters of the pair components) to be at least five times the pair component separation. Many of these pairs are also found in the Catalogue of Southern Peculiar Galaxies and Associations by Arp & Madore. We find that one of them, AM1907--504, is unlikely to be a physical pair because of the large velocity difference. The other 4 pairs are most likely physically bound with Delta-V ≤ 600 km/s. They can also be classified as true ES pairs since the photometric profiles for the early-type components obey an r1/4 law. We find diverse signs of interaction in our pair sample ranging from direct collisions to small distortions. In principle, this evidence is less ambiguous in mixed pairs because we are dealing with a single gas rich component. A strong but indirect form of evidence for interaction between the galaxies involves the detection of a young stellar component in the early-type members. We used Bica's stellar synthesis approach in order to detect the young stellar population in these pairs. We find that 10% to 37% of their fluxes arises from a young age population (< 5 x 108 years). We suggest that a transfer of gas appears to be the most likely way for the E components to acquire fuel for star formation activity. The only other alternative would be to invoke an unusual star formation history in ellipticals that inhabit mixed pairs.
根据许多星系形成的方案，星系的形态应该强烈地依赖于星系所处的环境，尤其是它形成的环境。因此，在成对的星系中，人们期望找到相似形态类型的成员。然而，对成对星系的形态学研究显示了两种不同的类型:由相似形态的星系组成的对(EE和SS)和混合形态的对(ES)，其中E代表早期型星系，S代表晚期型星系。事实上，在相当完整的双星系样本(例如Karachentsev的孤立星系对目录)中，相当大比例的双星对是混合型的。此外，混合副各分量径向速度差的分布与和谐型(尤其是SS)副相似。这进一步支持了大多数是物理二进制文件的论点。我们利用成像、光谱学和恒星群综合技术研究了5对混合星系(AM0327-285、AM1806-852、AM1907-504、AM2016-330、AM2055-492)的相互作用效应。目前的双星样本来自于在ESO巡天的视觉搜索中发现的126个候选混合双星样本。采用了一种隔离准则，要求到最近邻居的距离(长轴直径≥对组件直径)至少是对组件距离的5倍。许多这样的星系对也可以在Arp & Madore的《南方特殊星系和星系协会目录》中找到。我们发现其中一个，AM1907—504，不太可能是物理对，因为速度差很大。其余4对极有可能与δ - v≤600 km/s物理结合。它们也可以被归类为真正的ES对，因为早期组分的光度分布服从r1/4定律。我们在我们的配对样本中发现了各种各样的相互作用迹象，从直接碰撞到小的扭曲。原则上，这种证据在混合对中不那么模棱两可，因为我们处理的是单一的富含气体的成分。星系之间相互作用的一个强有力但间接的证据包括在早期型成员中探测到年轻的恒星成分。我们使用比卡星的恒星合成方法来探测这些对中的年轻恒星群。我们发现10%至37%的流量来自年轻人口(< 5 x 108岁)。我们认为，气体的转移似乎是E组分获得恒星形成活动燃料的最有可能的方式。唯一的另一种选择是在混合对的椭圆中调用不寻常的恒星形成历史。
{"title":"MIXED PAIRS OF GALAXIES","authors":"Duilia Fernandes de Mello","doi":"10.1086/133668","DOIUrl":"https://doi.org/10.1086/133668","url":null,"abstract":"According to many schemes for galaxy formation, galaxy morphology should depend strongly on the environment in which a galaxy resides and, especially, in which it was formed. Therefore, in pairs of galaxies one expects to find members of similar morphological type. However, morphological studies of paired galaxies show two different categories: pairs formed by galaxies with similar morphology (EE and SS) and pairs of mixed morphology (ES), where E represents early--type galaxies and S represents late--types. Actually a significant percentage of pairs in reasonably complete samples of binary galaxies (e.g. Catalog of Isolated Pairs of Galaxies by Karachentsev) are of mixed type. Moreover, the distribution of radial velocity differences between components of mixed pairs is similar to that for concordant type (especially SS) pairs. This is further support for the contention that most are physical binaries. We used imaging, spectroscopy and stellar population synthesis to study the interaction effects in 5 mixed pairs of galaxies (AM0327-285, AM1806-852, AM1907-504, AM2016-330, AM2055-492). The present pair sample originated from a sample of 126 candidate mixed pairs that were found during a visual search on the ESO sky surveys. An isolation criterion was employed that required the distance to the nearest neighbor (with major axis diameter ≥ the diameters of the pair components) to be at least five times the pair component separation. Many of these pairs are also found in the Catalogue of Southern Peculiar Galaxies and Associations by Arp & Madore. We find that one of them, AM1907--504, is unlikely to be a physical pair because of the large velocity difference. The other 4 pairs are most likely physically bound with Delta-V ≤ 600 km/s. They can also be classified as true ES pairs since the photometric profiles for the early-type components obey an r1/4 law. We find diverse signs of interaction in our pair sample ranging from direct collisions to small distortions. In principle, this evidence is less ambiguous in mixed pairs because we are dealing with a single gas rich component. A strong but indirect form of evidence for interaction between the galaxies involves the detection of a young stellar component in the early-type members. We used Bica's stellar synthesis approach in order to detect the young stellar population in these pairs. We find that 10% to 37% of their fluxes arises from a young age population (< 5 x 108 years). We suggest that a transfer of gas appears to be the most likely way for the E components to acquire fuel for star formation activity. The only other alternative would be to invoke an unusual star formation history in ellipticals that inhabit mixed pairs.","PeriodicalId":80579,"journal":{"name":"Astrophysical letters & communications","volume":"107 1","pages":"1129 - 1129"},"PeriodicalIF":0.0,"publicationDate":"1995-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60509661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1994-01-01DOI: 10.1007/978-94-011-1146-1_145
G. Vettolani, E. Zucca, A. Cappi, R. Merighins, M. Mignoli, G. Stirpe, G. Zamorani, H. Macgillivray, C. Collins, C. Balkowski, J. Alimi, A. Blanchard, V. Cayatte, P. Felenbok, S. Maurogordato, D. Proust, G. Chincarini, L. Guzzo, D. Maccagni, R. Scaramella, M. Ramella
{"title":"A Redshift Survey in the South Galactic Pole Region","authors":"G. Vettolani, E. Zucca, A. Cappi, R. Merighins, M. Mignoli, G. Stirpe, G. Zamorani, H. Macgillivray, C. Collins, C. Balkowski, J. Alimi, A. Blanchard, V. Cayatte, P. Felenbok, S. Maurogordato, D. Proust, G. Chincarini, L. Guzzo, D. Maccagni, R. Scaramella, M. Ramella","doi":"10.1007/978-94-011-1146-1_145","DOIUrl":"https://doi.org/10.1007/978-94-011-1146-1_145","url":null,"abstract":"","PeriodicalId":80579,"journal":{"name":"Astrophysical letters & communications","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1994-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51663941","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We have derived a new period-luminosity (PL) relation for galactic Cepheids in open clusters and associations from the Zero-Age Main-Sequence (ZAMS)-fitting method, using the most reliable cluster photometric data and Cepheid reddening data available, and homogeneous treatment of absorption corrections. For about half of the cluster Cepheid sample (17 stars) we also derive distances and absolute magnitudes from the surface-brightness method. From a comparison we find that the surface-brightness PL relation has a zero point about 0.15 mag brighter than the cluster ZAMS-fitting PL relation, but in view of the sources of systematic error involved in both methods, this discrepancy is clearly not significant
{"title":"Comparison of the open cluster and surface brightness distance scales for galactic classical cepheids","authors":"P. Fouqué, W. Gieren","doi":"10.1086/116679","DOIUrl":"https://doi.org/10.1086/116679","url":null,"abstract":"We have derived a new period-luminosity (PL) relation for galactic Cepheids in open clusters and associations from the Zero-Age Main-Sequence (ZAMS)-fitting method, using the most reliable cluster photometric data and Cepheid reddening data available, and homogeneous treatment of absorption corrections. For about half of the cluster Cepheid sample (17 stars) we also derive distances and absolute magnitudes from the surface-brightness method. From a comparison we find that the surface-brightness PL relation has a zero point about 0.15 mag brighter than the cluster ZAMS-fitting PL relation, but in view of the sources of systematic error involved in both methods, this discrepancy is clearly not significant","PeriodicalId":80579,"journal":{"name":"Astrophysical letters & communications","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1993-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60836144","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1986-01-01DOI: 10.1007/978-94-009-3785-7
T. Henning, B. Stecklum
{"title":"Book-Review - the Role of Dust in Dense Regions of Interstellar Matter","authors":"T. Henning, B. Stecklum","doi":"10.1007/978-94-009-3785-7","DOIUrl":"https://doi.org/10.1007/978-94-009-3785-7","url":null,"abstract":"","PeriodicalId":80579,"journal":{"name":"Astrophysical letters & communications","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1986-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51530220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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