{"title":"Solar Irradiance Variability and Luminosity Changes","authors":"P. Foukal","doi":"10.1017/S1539299600011242","DOIUrl":"https://doi.org/10.1017/S1539299600011242","url":null,"abstract":"This review presents a discussion of radiometric measurements of solar total irradiance variation, AS, on time scales of days, to the 15-year extent of present measurements. It does not cover variations in spectral irradi ance, particularly the relatively large solar UV and EUV flux variations of great importance in studies of trends in stratospheric ozone, and of upper atmospheric heating variations. Analysis of the pyrheliometry of AS carried out from the Solar Maxi mum Mission, Nimbus-7 and ERBS satellites has shown that a) the sun brightens by 0.05 - 0.1% around activity maximum and; b) it dims by up to approximately 0.2% when large sunspot groups cross the disc. Empirical models of AS based on areas and photometric contrasts of sunspots, and on proxies of facular area, are remarkably successful in matching the observed record of AS, on time scales between days and the full 15- year record available since 1978. These models indicate that the opposite contributions of sunspots and faculae in active regions roughly balance over time scales of years, and the net solar brightening observed around peak activity is caused by increased emission from the photospheric magnetic network. model. the when least","PeriodicalId":422890,"journal":{"name":"Highlights of Astronomy","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124852468","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":"Water in Sunspots and Stars","authors":"P. Bernath","doi":"10.1017/S1539299600012867","DOIUrl":"https://doi.org/10.1017/S1539299600012867","url":null,"abstract":"","PeriodicalId":422890,"journal":{"name":"Highlights of Astronomy","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124854198","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":"16. Public Education to Preserve Dark Skies and Astronomical Windows With Eavesdropping and Robotic Telescopes","authors":"J. Baruch","doi":"10.1017/S153929960002058X","DOIUrl":"https://doi.org/10.1017/S153929960002058X","url":null,"abstract":"","PeriodicalId":422890,"journal":{"name":"Highlights of Astronomy","volume":"186 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124926772","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":"The supernebula and protoglobular cluster in NGC 5253","authors":"J. Turner","doi":"10.1017/S1539299600013204","DOIUrl":"https://doi.org/10.1017/S1539299600013204","url":null,"abstract":". A compact and bright radio and infrared source within the starburst center of the dwarf galaxy NGC 5253 appears to be an extremely large compact HII region. The high density (n e ~ few xlO 4 cm -3 ) and size (~l-2 pc) of the nebula require the ionization equivalent of at least 4000 07 stars. We suggest that this optically obscured nebula is a forming super star cluster, or protoglobular cluster, with an age of a few hundred thousand years.","PeriodicalId":422890,"journal":{"name":"Highlights of Astronomy","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124965042","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}
C. Anguita, G. Carrasco, P. Loyola, V. Šiškina, M. S. Zverev
{"title":"Meridian Observations at Santiago, Chile","authors":"C. Anguita, G. Carrasco, P. Loyola, V. Šiškina, M. S. Zverev","doi":"10.1007/978-94-010-3417-3_34","DOIUrl":"https://doi.org/10.1007/978-94-010-3417-3_34","url":null,"abstract":"","PeriodicalId":422890,"journal":{"name":"Highlights of Astronomy","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125099089","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":"Strategies for Establishing Astronomy in Developing Countries","authors":"M. Othman","doi":"10.1017/S153929960001902X","DOIUrl":"https://doi.org/10.1017/S153929960001902X","url":null,"abstract":"Developing countries have their own particular political, economic and cultural circumstances. There are, therefore, no unique solutions. However there are some factors which are common to all or most of them, namely the lack of human and financial resources and in most cases an absence of a political commitment to the advancement of science. Such situations are in a sense not peculiar to developing nations because in some developed countries astronomy has a’ developing’ status. Even in countries where astronomy is well established, the commitment and allocations required to maintain the status quo need to be continuously addressed. Hence strategies for fighting this ”constant battle” are relevant to all astronomers of the world, while being especially vital to those in the developing world.","PeriodicalId":422890,"journal":{"name":"Highlights of Astronomy","volume":"91 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125174758","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":"Future Large Scale Facilities in Astronomy","authors":"H. Butcher","doi":"10.1017/S1539299600021547","DOIUrl":"https://doi.org/10.1017/S1539299600021547","url":null,"abstract":"","PeriodicalId":422890,"journal":{"name":"Highlights of Astronomy","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125903907","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":"Dynamic Catastrophes in Stars","authors":"J. Perdang","doi":"10.1017/S1539299600004366","DOIUrl":"https://doi.org/10.1017/S1539299600004366","url":null,"abstract":"","PeriodicalId":422890,"journal":{"name":"Highlights of Astronomy","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125924602","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":"X-Ray Variability in Active Galactic Nuclei: Two Things That Everybody Should Know","authors":"K. Leighly","doi":"10.1017/S1539299600018839","DOIUrl":"https://doi.org/10.1017/S1539299600018839","url":null,"abstract":"X-ray variability is a distinguishing property of Active Galactic Nuclei (AGN), and the energetics and time scales of the emission dictate that the X-rays must originate very close to the central engine. In this review I discuss two basic topics from AGN variability research. The first is the correlation of the variability time scale with the X-ray luminosity, and the second is the structure of the X-ray light curve. In each case, I first review the old results that have been known for approximately the last 10 years and then I discuss very new results which may force us to modify our ideas about the origin of AGN X-ray variability. Note that I am discussing the variability of non-blazar type AGN.","PeriodicalId":422890,"journal":{"name":"Highlights of Astronomy","volume":"13 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126163106","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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