The ratio of penumbral to umbra area of sunspots plays a crucial role in the solar physics fields, especially for understanding the origin and evolution of the solar activity cycle. By analyzing the recently digitized...The ratio of penumbral to umbra area of sunspots plays a crucial role in the solar physics fields, especially for understanding the origin and evolution of the solar activity cycle. By analyzing the recently digitized sunspot drawings observed from Yunnan Observatories(1957–2021), we investigate the long-term variation of the penumbral to umbra area ratio of sunspots. An automatic extraction method, based on the maximum between-class variance and the morphological discrimination, is used to accurately extract penumbra and umbra and to calculate the ratio over six solar cycles(cycle 19–24). The expected value of the ratio of penumbra to umbra area is found to be 6.63 ± 0.98, and it does not exhibit any systematic variation with sunspot latitudes and phases. The average ratio fluctuates from 5 to 7.5 per year and the overall trend has decreased after 1999 compared to the previous one.The ratio of sunspot penumbra to umbra area satisfies the log-normal distribution, implying that its variation is related to the evolution of the photospheric magnetic field. Our results are consistent with previous works.展开更多
In the relativistic mean field theory and cooling theories,relativistic correction on neutrino emission from neutron stars in four typical nuclear parameter sets,GM1,GL85,GPS250 and GPS300 is studied.Results show that...In the relativistic mean field theory and cooling theories,relativistic correction on neutrino emission from neutron stars in four typical nuclear parameter sets,GM1,GL85,GPS250 and GPS300 is studied.Results show that relativistic effect makes the neutrino emissivity,neutrino luminosity and cooling rate lower,compared with the nonrelativistic case.And the influence of relativistic effect grows with the mass of the neutron star.GPS300 set leads to the biggest fall in neutrino emissivity,whereas GM1 set leads to the largest disparity in cooling rate caused by relativistic effect.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. U2031202 and U1731124)the special foundation work of the Ministry of Science and Technology of China (Grant No. 2014FY120300)the 13th Five-year Informatization Plan of Chinese Academy of Sciences (Grant No. XXH13505-04)。
文摘The ratio of penumbral to umbra area of sunspots plays a crucial role in the solar physics fields, especially for understanding the origin and evolution of the solar activity cycle. By analyzing the recently digitized sunspot drawings observed from Yunnan Observatories(1957–2021), we investigate the long-term variation of the penumbral to umbra area ratio of sunspots. An automatic extraction method, based on the maximum between-class variance and the morphological discrimination, is used to accurately extract penumbra and umbra and to calculate the ratio over six solar cycles(cycle 19–24). The expected value of the ratio of penumbra to umbra area is found to be 6.63 ± 0.98, and it does not exhibit any systematic variation with sunspot latitudes and phases. The average ratio fluctuates from 5 to 7.5 per year and the overall trend has decreased after 1999 compared to the previous one.The ratio of sunspot penumbra to umbra area satisfies the log-normal distribution, implying that its variation is related to the evolution of the photospheric magnetic field. Our results are consistent with previous works.
基金Supported in part by National Natural Science Foundation of China under Grant Nos.11265009,11175077,11271055General Project of Liaoning Provincial Department of Education under Grant No.L2015005
文摘In the relativistic mean field theory and cooling theories,relativistic correction on neutrino emission from neutron stars in four typical nuclear parameter sets,GM1,GL85,GPS250 and GPS300 is studied.Results show that relativistic effect makes the neutrino emissivity,neutrino luminosity and cooling rate lower,compared with the nonrelativistic case.And the influence of relativistic effect grows with the mass of the neutron star.GPS300 set leads to the biggest fall in neutrino emissivity,whereas GM1 set leads to the largest disparity in cooling rate caused by relativistic effect.
