Pub Date : 2006-10-01DOI: 10.1017/S1539299600017603
Guangyu Li, W. Ni, C. Tang
ASTROD I is the first step of ASTROD (Astrodynamical Space Test of Relativity using Optical Devices). This mission concept has one spacecraft carrying a payload of a telescope, five lasers, and a clock together with ground stations (ODSN: Optical Deep Space Network) to test the optical scheme of interferometric and pulse ranging and yet give important scientific results. These scientific results include a better measurement of the relativistic parameters, a better sensitivity in using optical Doppler tracking method for detecting gravitational waves, and measurement of many solar system parameters more precisely. The weight of this spacecraft is estimated to be about 300-350 kg with a payload of about 100-120 kg. The spacecraft is to be launched with initial period about 290 days and to pass by Venus twice to receive gravity-assistance for achieving shorter periods. For a launch on August 4, 2010, after two encounters with Venus, the orbital period can be shortened to 165 days. After about 370 days from launch, the spacecraft will arrive at the other side of the Sun for the determination of relativistic parameters.
ASTROD I是ASTROD (astrodynamic Space Test of Relativity with Optical Devices)的第一步。这个任务概念有一个航天器携带一个望远镜、五个激光器和一个时钟以及地面站(ODSN:光深空网络)来测试干涉测量和脉冲测距的光学方案，并给出重要的科学结果。这些科学成果包括更好地测量相对论参数，使用光学多普勒跟踪方法探测引力波的灵敏度更高，以及更精确地测量许多太阳系参数。该航天器的重量估计约为300-350公斤，有效载荷约为100-120公斤。该航天器的初始发射周期约为290天，并将经过金星两次，以获得重力帮助，以实现更短的周期。如果在2010年8月4日发射，在两次与金星相遇后，轨道周期可以缩短到165天。在发射大约370天后，宇宙飞船将到达太阳的另一侧，以确定相对论参数。
{"title":"ASTROD I: Mission Concept and Venus Flybys","authors":"Guangyu Li, W. Ni, C. Tang","doi":"10.1017/S1539299600017603","DOIUrl":"https://doi.org/10.1017/S1539299600017603","url":null,"abstract":"ASTROD I is the first step of ASTROD (Astrodynamical Space Test of Relativity using Optical Devices). This mission concept has one spacecraft carrying a payload of a telescope, five lasers, and a clock together with ground stations (ODSN: Optical Deep Space Network) to test the optical scheme of interferometric and pulse ranging and yet give important scientific results. These scientific results include a better measurement of the relativistic parameters, a better sensitivity in using optical Doppler tracking method for detecting gravitational waves, and measurement of many solar system parameters more precisely. The weight of this spacecraft is estimated to be about 300-350 kg with a payload of about 100-120 kg. The spacecraft is to be launched with initial period about 290 days and to pass by Venus twice to receive gravity-assistance for achieving shorter periods. For a launch on August 4, 2010, after two encounters with Venus, the orbital period can be shortened to 165 days. After about 370 days from launch, the spacecraft will arrive at the other side of the Sun for the determination of relativistic parameters.","PeriodicalId":422890,"journal":{"name":"Highlights of Astronomy","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124926159","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 : 2005-04-01DOI: 10.1017/S1539299600017500
J. Lebreton, D. Matson
Huygens is an entry probe designed to descend under parachute through the atmosphere of Titan, Saturn’s largest moon. The Huygens Probe is provided by the European Space Agency (ESA) for the Cassini/Huygens mission to Saturn and Titan. The Huygens mission will be conducted on the 3rd Orbit around Saturn. The probe will be released around December 25, 2004 for entry in Titan on January 14, 2005. This paper provided an overview of the Huygens mission. The status of the probe and of the mission was reviewed, and opportunities for Titan observations by the Orbiter during the first two orbits were discussed. The Cassini/Huygens mission is a joint undertaking by NASA and ESA, with ASI as a partner via a bilateral agreement with NASA.
{"title":"The Huygens Mission to Titan: Overview and status","authors":"J. Lebreton, D. Matson","doi":"10.1017/S1539299600017500","DOIUrl":"https://doi.org/10.1017/S1539299600017500","url":null,"abstract":"Huygens is an entry probe designed to descend under parachute through the atmosphere of Titan, Saturn’s largest moon. The Huygens Probe is provided by the European Space Agency (ESA) for the Cassini/Huygens mission to Saturn and Titan. The Huygens mission will be conducted on the 3rd Orbit around Saturn. The probe will be released around December 25, 2004 for entry in Titan on January 14, 2005. This paper provided an overview of the Huygens mission. The status of the probe and of the mission was reviewed, and opportunities for Titan observations by the Orbiter during the first two orbits were discussed. The Cassini/Huygens mission is a joint undertaking by NASA and ESA, with ASI as a partner via a bilateral agreement with NASA.","PeriodicalId":422890,"journal":{"name":"Highlights of Astronomy","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126630400","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 : 2003-12-19DOI: 10.1017/S1539299600015197
A. Brandenburg, E. Blackman
It is argued that much of the observed magnetic helicity losses at the solar surface may represent a reduction of an otherwise more dominant nonlinearity of solar and stellar dynamos. This nonlinearity is proportional to the internal twist (as opposed to writhe) of helical and sigmoidal surface structures.
{"title":"Ejection of Bi-Helical Fields from the Sun","authors":"A. Brandenburg, E. Blackman","doi":"10.1017/S1539299600015197","DOIUrl":"https://doi.org/10.1017/S1539299600015197","url":null,"abstract":"It is argued that much of the observed magnetic helicity losses at the solar surface may represent a reduction of an otherwise more dominant nonlinearity of solar and stellar dynamos. This nonlinearity is proportional to the internal twist (as opposed to writhe) of helical and sigmoidal surface structures.","PeriodicalId":422890,"journal":{"name":"Highlights of Astronomy","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132569089","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 : 2003-10-29DOI: 10.1017/S1539299600016543
J. Prochaska
I briefly draw comparisons between the fields of damped Lya and metal-poor stellar abundances. In particular, I examine their complementary age-metallicity relations and comparisons between the damped Lya and dwarf galaxy abundance patterns. Regarding the latter, I describe a series of problems concerning associating high z damped Lya systems with present-day dwarfs.
{"title":"Comparing Chemical Abundances of the Damped Lyα Systems and Metal-Poor Stars","authors":"J. Prochaska","doi":"10.1017/S1539299600016543","DOIUrl":"https://doi.org/10.1017/S1539299600016543","url":null,"abstract":"I briefly draw comparisons between the fields of damped Lya and metal-poor stellar abundances. In particular, I examine their complementary age-metallicity relations and comparisons between the damped Lya and dwarf galaxy abundance patterns. Regarding the latter, I describe a series of problems concerning associating high z damped Lya systems with present-day dwarfs.","PeriodicalId":422890,"journal":{"name":"Highlights of Astronomy","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114793968","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 : 2003-10-28DOI: 10.1017/S1539299600016658
Julia C. Lee
Highlights of interesting astrophysical discoveries are reviewed in the context of high resolution X-ray spectroscopy made possible with Chandra and XMM-Newton, and its relevance to atomic physics calculations and measurements is discussed. These spectra have shown that the overlap between astrophysics and atomic physics is stronger than ever, as discoveries of new X-ray lines and edge structure is matching the need for increasingly detailed theoretical calculations and experimental measurements of atomic data.
{"title":"Probing X-ray Emitting Plasma with High Resolution Chandra and XMM-Newton Spectra","authors":"Julia C. Lee","doi":"10.1017/S1539299600016658","DOIUrl":"https://doi.org/10.1017/S1539299600016658","url":null,"abstract":"Highlights of interesting astrophysical discoveries are reviewed in the context of high resolution X-ray spectroscopy made possible with Chandra and XMM-Newton, and its relevance to atomic physics calculations and measurements is discussed. These spectra have shown that the overlap between astrophysics and atomic physics is stronger than ever, as discoveries of new X-ray lines and edge structure is matching the need for increasingly detailed theoretical calculations and experimental measurements of atomic data.","PeriodicalId":422890,"journal":{"name":"Highlights of Astronomy","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116504649","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 : 2003-10-27DOI: 10.1017/S1539299600014945
A. McDonald
The current knowledge of neutrino properties has been derived from measurements performed with both astrophysical and terrestrial sources. Observations of neutrino flavor change have been made with neutrinos generated in the solar core, through cosmic ray interactions in the atmosphere and in nuclear reactors. A summary is presented of the current knowledge of neutrino properties and a description is provided for future measurements that could provide more complete information on neutrino properties.
{"title":"Neutrino Properties from Measurements using Astrophysical and Terrestrial Sources","authors":"A. McDonald","doi":"10.1017/S1539299600014945","DOIUrl":"https://doi.org/10.1017/S1539299600014945","url":null,"abstract":"The current knowledge of neutrino properties has been derived from measurements performed with both astrophysical and terrestrial sources. Observations of neutrino flavor change have been made with neutrinos generated in the solar core, through cosmic ray interactions in the atmosphere and in nuclear reactors. A summary is presented of the current knowledge of neutrino properties and a description is provided for future measurements that could provide more complete information on neutrino properties.","PeriodicalId":422890,"journal":{"name":"Highlights of Astronomy","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128061167","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 : 2003-10-23DOI: 10.1017/S1539299600016671
A. Pradhan
Ongoing activities under an international collaboration of atomic physicists and astrophysicists under the Iron Project and the RmaX Project, with applications to X-ray astronomy, are briefly described.
{"title":"The Iron Project and the RmaX Project","authors":"A. Pradhan","doi":"10.1017/S1539299600016671","DOIUrl":"https://doi.org/10.1017/S1539299600016671","url":null,"abstract":"Ongoing activities under an international collaboration of atomic physicists and astrophysicists under the Iron Project and the RmaX Project, with applications to X-ray astronomy, are briefly described.","PeriodicalId":422890,"journal":{"name":"Highlights of Astronomy","volume":"28 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131837352","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 : 2003-10-21DOI: 10.1017/S1539299600017299
S. Curran, J. Webb, M. Murphy, N. Wales., Australia., I. O. Astronomy, UK., N. Observatory, Japan.
Millimetre-band scans of the frequency space towards optically dim quasars is potentially a highly efficient method for detecting new high red-shift molecular absorption systems. Here we describe scans towards 7 quasars over wide bandwidths (up to 23 GHz) with sensitivity limits sufficient to detect the 4 redshifted absorbers already known. With wider frequency bands, highly efficient searches of large numbers of possibly obscured objects will yield many new molecular absorbers.
{"title":"Deep Searches for High Redshift Molecular Absorption","authors":"S. Curran, J. Webb, M. Murphy, N. Wales., Australia., I. O. Astronomy, UK., N. Observatory, Japan.","doi":"10.1017/S1539299600017299","DOIUrl":"https://doi.org/10.1017/S1539299600017299","url":null,"abstract":"Millimetre-band scans of the frequency space towards optically dim quasars is potentially a highly efficient method for detecting new high red-shift molecular absorption systems. Here we describe scans towards 7 quasars over wide bandwidths (up to 23 GHz) with sensitivity limits sufficient to detect the 4 redshifted absorbers already known. With wider frequency bands, highly efficient searches of large numbers of possibly obscured objects will yield many new molecular absorbers.","PeriodicalId":422890,"journal":{"name":"Highlights of Astronomy","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128394762","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 : 2003-10-21DOI: 10.1017/S1539299600015574
U. F. Alvensleben, P. Anders, R. S. U. Goettingen, U. Sheffield
Evolutionary synthesis models for star clusters of various metallicities including gaseous emission during the lifetime of the ionising stars are used to model star cluster systems comprising two populations: an old metal-poor globular clusters (GC) population similar to that of the Milky Way halo and a second GC population of arbitrary metallicity. We investigate the time evolution of color distributions and luminosity functions for the two GC populations in comparison with observations on E/S0 galaxies. We show that multi-passband data for GC populations give clues to the relative ages and metallicities of blue and red subpopulations and help constrain formation scenarios for their parent galaxies.
{"title":"From young to old: spectral models for star cluster systems","authors":"U. F. Alvensleben, P. Anders, R. S. U. Goettingen, U. Sheffield","doi":"10.1017/S1539299600015574","DOIUrl":"https://doi.org/10.1017/S1539299600015574","url":null,"abstract":"Evolutionary synthesis models for star clusters of various metallicities including gaseous emission during the lifetime of the ionising stars are used to model star cluster systems comprising two populations: an old metal-poor globular clusters (GC) population similar to that of the Milky Way halo and a second GC population of arbitrary metallicity. We investigate the time evolution of color distributions and luminosity functions for the two GC populations in comparison with observations on E/S0 galaxies. We show that multi-passband data for GC populations give clues to the relative ages and metallicities of blue and red subpopulations and help constrain formation scenarios for their parent galaxies.","PeriodicalId":422890,"journal":{"name":"Highlights of Astronomy","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116842976","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 : 2003-10-20DOI: 10.1017/S1539299600015951
V. Gurzadyan
I argue that the widely adopted framework of stellar dynamics survived since 1940s, is not fitting the current knowledge on non-linear systems. Borrowed from plasma physics when several fundamental features of perturbed non-linear systems were unknown, that framework ignores the difference in the role of perturbations in two different classes of systems, in plasma with Debye screening and gravitating systems with no screening. Now, when the revolutionary role of chaotic effects is revealed even in planetary dynamics i.e. for nearly integrable systems, one would expect that for stellar systems, i.e. non-integrable systems, their role have to be far more crucial. Indeed, ergodic theory tools already enabled to prove that spherical stellar systems are exponentially instable due to N-body interactions, while the two-body encounters, contrary to existing belief, are not the dominating mechanism of their relaxation. Chaotic effects distinguish morphological and other properties of galaxies. Using the Ricci curvature criterion, one can also show that a central massive object (nucleus) makes the N-body gravitating system more instable (chaotic), while systems with double nuclei are even more instable than those with a single one.
{"title":"A physicist's view of stellar dynamics: dynamical instability of stellar systems","authors":"V. Gurzadyan","doi":"10.1017/S1539299600015951","DOIUrl":"https://doi.org/10.1017/S1539299600015951","url":null,"abstract":"I argue that the widely adopted framework of stellar dynamics survived since 1940s, is not fitting the current knowledge on non-linear systems. Borrowed from plasma physics when several fundamental features of perturbed non-linear systems were unknown, that framework ignores the difference in the role of perturbations in two different classes of systems, in plasma with Debye screening and gravitating systems with no screening. Now, when the revolutionary role of chaotic effects is revealed even in planetary dynamics i.e. for nearly integrable systems, one would expect that for stellar systems, i.e. non-integrable systems, their role have to be far more crucial. Indeed, ergodic theory tools already enabled to prove that spherical stellar systems are exponentially instable due to N-body interactions, while the two-body encounters, contrary to existing belief, are not the dominating mechanism of their relaxation. Chaotic effects distinguish morphological and other properties of galaxies. Using the Ricci curvature criterion, one can also show that a central massive object (nucleus) makes the N-body gravitating system more instable (chaotic), while systems with double nuclei are even more instable than those with a single one.","PeriodicalId":422890,"journal":{"name":"Highlights of Astronomy","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134438279","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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