We present time resolved optical light curves in R bands obtained from differential photometry on sequential CCD frams of 4 new discovered high galactic latitude CVs, which are discovered by our spectroscopic observat...We present time resolved optical light curves in R bands obtained from differential photometry on sequential CCD frams of 4 new discovered high galactic latitude CVs, which are discovered by our spectroscopic observations of the optical identification of ROSAT X ray sources. The analysis of the light curves shows repeatable periodicity in these objects. J020348 7+295921 exhibits 0 5m variation with orbital period of 258 min. J062518 2+733433 reveals a 0 3 mag modulation with orbital period of 254min. J230949 6+213523 shows probably both orbital period of 207 min and WD spin period of 25 min. J232953 9+062814 present short period of 32min, indicating a magnetic system.展开更多
We present a method of calculating the scale height of non-edge-on spiral galaxies, together with a formula for errors. The method is based on solving Poisson＇s equation for a logarithmic disturbance of matter densit...We present a method of calculating the scale height of non-edge-on spiral galaxies, together with a formula for errors. The method is based on solving Poisson＇s equation for a logarithmic disturbance of matter density in spiral galaxies. We show that the spiral arms can not extend to inside the ＂forbidden radius＂ r0, due to the effect of the finite thickness of the disk. The method is tested by re-calculating the scale heights of 71 northern spiral galaxies previously calculated by Ma, Peng ＆ Gu. Our results differ from theirs by less than 9%. We also present the scale heights of a further 23 non-edge-on spiral galaxies.展开更多
文摘We present time resolved optical light curves in R bands obtained from differential photometry on sequential CCD frams of 4 new discovered high galactic latitude CVs, which are discovered by our spectroscopic observations of the optical identification of ROSAT X ray sources. The analysis of the light curves shows repeatable periodicity in these objects. J020348 7+295921 exhibits 0 5m variation with orbital period of 258 min. J062518 2+733433 reveals a 0 3 mag modulation with orbital period of 254min. J230949 6+213523 shows probably both orbital period of 207 min and WD spin period of 25 min. J232953 9+062814 present short period of 32min, indicating a magnetic system.
基金Supported by the National Natural Science Foundation of China
文摘We present a method of calculating the scale height of non-edge-on spiral galaxies, together with a formula for errors. The method is based on solving Poisson＇s equation for a logarithmic disturbance of matter density in spiral galaxies. We show that the spiral arms can not extend to inside the ＂forbidden radius＂ r0, due to the effect of the finite thickness of the disk. The method is tested by re-calculating the scale heights of 71 northern spiral galaxies previously calculated by Ma, Peng ＆ Gu. Our results differ from theirs by less than 9%. We also present the scale heights of a further 23 non-edge-on spiral galaxies.
