Discovery of a Jupiter/Saturn analog with gravitational microlensing     

Gaudi BS  Bennett DP  Udalski A  Gould A  Christie GW  Maoz D  Dong S  McCormick J  Szymanski MK  Tristram PJ  Nikolaev S  Paczynski B  Kubiak M  Pietrzynski G  Soszynski I  Szewczyk O  Ulaczyk K  Wyrzykowski L;OGLE Collaboration  Depoy DL  Han C  Kaspi S  Lee CU  Mallia F  Natusch T  Pogge RW  Park BG;MuFUN Collaboration  Abe F  Bond IA  Botzler CS  Fukui A  Hearnshaw JB  Itow Y  Kamiya K  Korpela AV  Kilmartin PM  Lin W  Masuda K  Matsubara Y  Motomura M  Muraki Y  Nakamura S  Okumura T  Ohnishi K  Rattenbury NJ  Sako T  Saito T  Sato S 《Science (New York, N.Y.)》2008,319(5865):927-930

Searches for extrasolar planets have uncovered an astonishing diversity of planetary systems, yet the frequency of solar system analogs remains unknown. The gravitational microlensing planet search method is potentially sensitive to multiple-planet systems containing analogs of all the solar system planets except Mercury. We report the detection of a multiple-planet system with microlensing. We identify two planets with masses of approximately 0.71 and approximately 0.27 times the mass of Jupiter and orbital separations of approximately 2.3 and approximately 4.6 astronomical units orbiting a primary star of mass approximately 0.50 solar mass at a distance of approximately 1.5 kiloparsecs. This system resembles a scaled version of our solar system in that the mass ratio, separation ratio, and equilibrium temperatures of the planets are similar to those of Jupiter and Saturn. These planets could not have been detected with other techniques; their discovery from only six confirmed microlensing planet detections suggests that solar system analogs may be common.  相似文献   

Search for low-mass exoplanets by gravitational microlensing at high magnification     

Abe F  Bennett DP  Bond IA  Eguchi S  Furuta Y  Hearnshaw JB  Kamiya K  Kilmartin PM  Kurata Y  Masuda K  Matsubara Y  Muraki Y  Noda S  Okajima K  Rakich A  Rattenbury NJ  Sako T  Sekiguchi T  Sullivan DJ  Sumi T  Tristram PJ  Yanagisawa T  Yock PC  Gal-Yam A  Lipkin Y  Maoz D  Ofek EO  Udalski A  Szewczyk O  Zebrun K  Soszynski I  Szymanski MK  Kubiak M  Pietrzynski G  Wyrzykowski L 《Science (New York, N.Y.)》2004,305(5688):1264-1266

Observations of the gravitational microlensing event MOA 2003-BLG-32/OGLE 2003-BLG-219 are presented, for which the peak magnification was over 500, the highest yet reported. Continuous observations around the peak enabled a sensitive search for planets orbiting the lens star. No planets were detected. Planets 1.3 times heavier than Earth were excluded from more than 50% of the projected annular region from approximately 2.3 to 3.6 astronomical units surrounding the lens star, Uranus-mass planets were excluded from 0.9 to 8.7 astronomical units, and planets 1.3 times heavier than Saturn were excluded from 0.2 to 60 astronomical units. These are the largest regions of sensitivity yet achieved in searches for extrasolar planets orbiting any star.  相似文献   

Development of the soil macrofauna community under silvopastoral and agrosilvicultural systems in Amazonia     

Eleusa Barros  Acacia Neves  Eric Blanchart  Erick C.M. Fernandes  Elisa Wandelli  Patrick Lavelle 《Pedobiologia》2003,47(3):273-280

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Genetic Analyses for TSV-Susceptible and TSV-Resistant Pacific White Shrimp Litopenaeus vannamei using M1 Microsatellite     

Zhenkang  Xu  Jennifer  Wyrzykowski Acacia  Alcivar-Warren Shaun M.  Moss  Brad J.  Argue  Steve M.  Arce  Monica  Traub Fernanda R. O.  Calderon Jeffrey  Lotz Verlee  Breland 《Journal of the World Aquaculture Society》2003,34(3):332-343

Allelic frequency differences at the highly polymorphic MI microsatellite of B20 locus were examined in Taura Syndrome Virus (TSV)-susceptible (Kona) and TSV-resistant (Select) lines of Pacific white shrimp Litopenaeus vannamei . DNA was screened from 1,009 cultured L. vannamei , 166 from the Kona line and 843 (97 broodstock and 746 offspring) from the Select line. A total of 34 different MI alleles were found, 41.2% of which were shared by the two lines, and 58.2% were unique to either line. Only seven (20.6%) of the 34 alleles had similar frequencies in the two lines. The most frequent (22.4%) allele in the Select line (218 bp) was absent from the Kona line. The most frequent (9.6%) allele in the Kona line (236 bp) was not observed in the Select line. Significant genetic differentiation between the two lines was shown using contingency table analysis (X²= 891.20, df = 33, P < 0.0001), the exact test ( P < 0.00001), and F_st, analysis (0.06). Comparison of MI allele frequencies between the TSVresistant Select and TSV-susceptible Kona lines and between the top 12.5% (Top Select) and the bottom 12.5% (Bottom Select) surviving families to TSV challenge in the Select line suggested associations of MI alleles with TSV resistance. These observations suggest testable hypotheses in future experiments aimed at finding genetic markers associated with resistance to TSV and markers that could be used for marker-assisted selection of broodstock.  相似文献