{"title":"Optical polarimetry of x-ray selected BL Lacs 1989","authors":"R. Elston, B. Jannuzi, Paul S. Smith","doi":"10.1007/BFB0031169","DOIUrl":"https://doi.org/10.1007/BFB0031169","url":null,"abstract":"","PeriodicalId":9423,"journal":{"name":"Bulletin of the American Astronomical Society","volume":"62 1","pages":"253-256"},"PeriodicalIF":0.0,"publicationDate":"1989-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79245957","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 : 1989-01-01DOI: 10.1017/CBO9780511564772.007
L. Dones, M. Showalter, J. Cuzzi
The current status of efforts to model light scattering in the Uranian and Saturnian rings is briefly reviewed, with an emphasis on the treatment of thin, vertically warped, or clumpy rings. Consideration is given to observations of an opposition surge in the rings (indicating that they are physically thick) and possible reasons for the failure of classical models to predict the forward-scattering characteristics of the B and inner A rings of Saturn, the quadrupole brightness variations in the A ring, the increase in reflectivity with optical depth in the A and B rings, the increase in brightness with solar and observer angle in the B ring, and systematic brightness variations in images of the inner Cassini division. It is pointed out that some of these discrepancies are eliminated by the use of a ray-tracing simulation code which determines the singly scattered light from a layer one or many particles thick.
{"title":"Simulations of light scattering in planetary rings","authors":"L. Dones, M. Showalter, J. Cuzzi","doi":"10.1017/CBO9780511564772.007","DOIUrl":"https://doi.org/10.1017/CBO9780511564772.007","url":null,"abstract":"The current status of efforts to model light scattering in the Uranian and Saturnian rings is briefly reviewed, with an emphasis on the treatment of thin, vertically warped, or clumpy rings. Consideration is given to observations of an opposition surge in the rings (indicating that they are physically thick) and possible reasons for the failure of classical models to predict the forward-scattering characteristics of the B and inner A rings of Saturn, the quadrupole brightness variations in the A ring, the increase in reflectivity with optical depth in the A and B rings, the increase in brightness with solar and observer angle in the B ring, and systematic brightness variations in images of the inner Cassini division. It is pointed out that some of these discrepancies are eliminated by the use of a ray-tracing simulation code which determines the singly scattered light from a layer one or many particles thick.","PeriodicalId":9423,"journal":{"name":"Bulletin of the American Astronomical Society","volume":"16 1","pages":"929"},"PeriodicalIF":0.0,"publicationDate":"1989-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73296295","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 : 1989-01-01DOI: 10.1007/978-94-009-0919-9_26
R. Griffiths
{"title":"Star Formation and the X-Ray Background","authors":"R. Griffiths","doi":"10.1007/978-94-009-0919-9_26","DOIUrl":"https://doi.org/10.1007/978-94-009-0919-9_26","url":null,"abstract":"","PeriodicalId":9423,"journal":{"name":"Bulletin of the American Astronomical Society","volume":"86 1","pages":"235-241"},"PeriodicalIF":0.0,"publicationDate":"1989-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73976366","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}
X-ray observations indicate that M87/Virgo and NGC 1275/Perseus have cooling flows that are associated with accretion rates of 20-30 and 300-500 solar masses/year, respectively. An assessment is made as to whether star formation is necessarily occurring in these cooling flows by calculating constant mass-flux models for all reasonable parameter space. No constant-mass-flux models that are consistent with all of the relevant observations are found; hence, it is concluded that mass is dropping out of these cooling flows.
{"title":"Star formation in the cooling flows of M87/Virgo and NGC 1275/Perseus","authors":"Raymond E. White, C. Sarazin","doi":"10.1086/166959","DOIUrl":"https://doi.org/10.1086/166959","url":null,"abstract":"X-ray observations indicate that M87/Virgo and NGC 1275/Perseus have cooling flows that are associated with accretion rates of 20-30 and 300-500 solar masses/year, respectively. An assessment is made as to whether star formation is necessarily occurring in these cooling flows by calculating constant mass-flux models for all reasonable parameter space. No constant-mass-flux models that are consistent with all of the relevant observations are found; hence, it is concluded that mass is dropping out of these cooling flows.","PeriodicalId":9423,"journal":{"name":"Bulletin of the American Astronomical Society","volume":"25 1","pages":"1105"},"PeriodicalIF":0.0,"publicationDate":"1988-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73219020","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}
A. Title, T. Tarbell, K. Topka, S. Ferguson, R. Shine, S. Team
The Solar Optical Universal Polarimeter (SOUP) on Spacelab 2 collected movies of solar granulation completely free from atmospheric blurring, and are not degraded by pointint jitter (the pointing stability was 0.003 sec root mean square). The movies illustrate that the solar five minute oscillation has a major role in the appearance of solar granulation and that exploding granules are a common feature of the granule evolution. Using 3-D Fourier filtering techniques the oscillations were removed and it was demonstrated that the autocorrelation lifetime of granulation is a factor of two greater in magnetic field regions than in field-free quiet sun. Horizontal velocities were measured and flow patterns were observed on the scale of meso- and super granulation. In quiet regions the mean flow velocity is 370 m/s while in the magnetic regions it is about 125 m/s. It was also found that the root mean square (RMS) fluctuating horizonal velocity field is substantially greater in quiet sun than in strong magnetic field regions. By superimposing the location of exploding granules on the average flow maps it was found that they appear almost exclusively in the center of mesogranulation size flow cells. Because of the nonuniformity of the distribution of exploding granules, the evolution of the granulation pattern in mesogranule cell centers and boundaries differs fundamentally. It is clear from this study there is neither a typical granule nor a typical granule evolution.
{"title":"Statistical Properties of Solar Granulation Derived from the Soup Instrument on Spacelab 2","authors":"A. Title, T. Tarbell, K. Topka, S. Ferguson, R. Shine, S. Team","doi":"10.1086/167026","DOIUrl":"https://doi.org/10.1086/167026","url":null,"abstract":"The Solar Optical Universal Polarimeter (SOUP) on Spacelab 2 collected movies of solar granulation completely free from atmospheric blurring, and are not degraded by pointint jitter (the pointing stability was 0.003 sec root mean square). The movies illustrate that the solar five minute oscillation has a major role in the appearance of solar granulation and that exploding granules are a common feature of the granule evolution. Using 3-D Fourier filtering techniques the oscillations were removed and it was demonstrated that the autocorrelation lifetime of granulation is a factor of two greater in magnetic field regions than in field-free quiet sun. Horizontal velocities were measured and flow patterns were observed on the scale of meso- and super granulation. In quiet regions the mean flow velocity is 370 m/s while in the magnetic regions it is about 125 m/s. It was also found that the root mean square (RMS) fluctuating horizonal velocity field is substantially greater in quiet sun than in strong magnetic field regions. By superimposing the location of exploding granules on the average flow maps it was found that they appear almost exclusively in the center of mesogranulation size flow cells. Because of the nonuniformity of the distribution of exploding granules, the evolution of the granulation pattern in mesogranule cell centers and boundaries differs fundamentally. It is clear from this study there is neither a typical granule nor a typical granule evolution.","PeriodicalId":9423,"journal":{"name":"Bulletin of the American Astronomical Society","volume":"34 1","pages":"679"},"PeriodicalIF":0.0,"publicationDate":"1988-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85472746","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 : 1988-09-01DOI: 10.1007/978-94-009-0963-2_105
G. Cecil, J. Bland
{"title":"Imaging Spectrophotometry of the Narrow-Line Region NGC 1068","authors":"G. Cecil, J. Bland","doi":"10.1007/978-94-009-0963-2_105","DOIUrl":"https://doi.org/10.1007/978-94-009-0963-2_105","url":null,"abstract":"","PeriodicalId":9423,"journal":{"name":"Bulletin of the American Astronomical Society","volume":"16 1 1","pages":"970"},"PeriodicalIF":0.0,"publicationDate":"1988-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83026862","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 : 1988-09-01DOI: 10.1007/978-94-009-0963-2_130
M. Joy, E. Tollestrup, P. Harvey, P. Mcgregor, A. R. Hyland
{"title":"Longslit Optical Spectroscopy of Powerful Far-Infrared Galaxies","authors":"M. Joy, E. Tollestrup, P. Harvey, P. Mcgregor, A. R. Hyland","doi":"10.1007/978-94-009-0963-2_130","DOIUrl":"https://doi.org/10.1007/978-94-009-0963-2_130","url":null,"abstract":"","PeriodicalId":9423,"journal":{"name":"Bulletin of the American Astronomical Society","volume":"78 1","pages":"1000"},"PeriodicalIF":0.0,"publicationDate":"1988-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74160331","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 : 1988-09-01DOI: 10.1007/978-94-009-0963-2_36
P. Osmer, A. Porter, R. Green
{"title":"Quasar Emission Line Strengths","authors":"P. Osmer, A. Porter, R. Green","doi":"10.1007/978-94-009-0963-2_36","DOIUrl":"https://doi.org/10.1007/978-94-009-0963-2_36","url":null,"abstract":"","PeriodicalId":9423,"journal":{"name":"Bulletin of the American Astronomical Society","volume":"23 1","pages":"968"},"PeriodicalIF":0.0,"publicationDate":"1988-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81903103","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}
The response of a model solar atmosphere to heating by an electron beam has been studied for electron beam flux spectra which are power laws with low-energy knees (rising linearly with time to a peak at 30 s and then falling linearly to 0 at 60 s) ranging from 10 to 20 keV. The results indicate that high peak electron beam fluxes, low-energy knees, and larger spectral indices all move the atmospheric response toward greater enhancements of the parameters in the coronal regions of the atmosphere. Coronal responses can thus be used as a diagnostic of the parameters of the electron beam. 23 refs.
{"title":"Numerical Simulations of Impulsively Heated Solar Flares","authors":"J. Mariska, A. Emslie, P. Li","doi":"10.1086/167564","DOIUrl":"https://doi.org/10.1086/167564","url":null,"abstract":"The response of a model solar atmosphere to heating by an electron beam has been studied for electron beam flux spectra which are power laws with low-energy knees (rising linearly with time to a peak at 30 s and then falling linearly to 0 at 60 s) ranging from 10 to 20 keV. The results indicate that high peak electron beam fluxes, low-energy knees, and larger spectral indices all move the atmospheric response toward greater enhancements of the parameters in the coronal regions of the atmosphere. Coronal responses can thus be used as a diagnostic of the parameters of the electron beam. 23 refs.","PeriodicalId":9423,"journal":{"name":"Bulletin of the American Astronomical Society","volume":"8 1","pages":"715"},"PeriodicalIF":0.0,"publicationDate":"1988-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84471173","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 : 1988-01-01DOI: 10.1007/978-3-642-82971-0_169
Stephen J. Edberg, R. Newburn, J. Rahe
{"title":"The International Halley Watch.","authors":"Stephen J. Edberg, R. Newburn, J. Rahe","doi":"10.1007/978-3-642-82971-0_169","DOIUrl":"https://doi.org/10.1007/978-3-642-82971-0_169","url":null,"abstract":"","PeriodicalId":9423,"journal":{"name":"Bulletin of the American Astronomical Society","volume":"36 1","pages":"981-984"},"PeriodicalIF":0.0,"publicationDate":"1988-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75372252","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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