We wrote and used an automated flare detection Python script to search for super-flares on main sequence stars of types A,F,G,K and M in Kepler's long-cadence data from Q0 to Q17.We studied the statistical propert...We wrote and used an automated flare detection Python script to search for super-flares on main sequence stars of types A,F,G,K and M in Kepler's long-cadence data from Q0 to Q17.We studied the statistical properties of the occurrence rate of super-flares.For the G-type data set,we compared our results with the previous results of Okamoto et al.by splitting the data set into four rotational bands.We found similar power-law indices for the flare frequency distribution.Hence,we show that inclusion of a high-pass filter,sample biases,gyrochronology and completeness of flare detection is of no significance,as our results are similar to those of Okamoto et al.We estimated that a super-flare on G-type dwarfs with energy of 10^(35) erg occurs on a star once every 4360 yr.We found 4637 super-flares on 1896 G-type dwarfs.Moreover,we identified 321,1125,4538 and 5445 super-flares on 136,522,770 and 312 dwarfs of types A,F,K and M,respectively.We ascertained that the occurrence rate(dN/dE)of super-flares versus flare energy,E,shows a power-law distribution with dN/dE∝E^(-α),whereα■2.0 to 2.1 for the spectral types from F-type to M-type stars.In contrast,the obtainedα■1.3 for A-type stars suggests that the flare conditions differ from those of the other spectral-type stars.We note an increase in flare incidence rate in F-type to M-type stars and a decrease in A-type to F-type stars.展开更多
We present the results of our study of three previously unstudied short-period eclipsing binaries, namely: ASAS 110609 ﹣ 2045.3, ASAS105331 ﹣ 7424.7, and ASAS 130057 + 2120.3. Using the visual (V)-band data obtained...We present the results of our study of three previously unstudied short-period eclipsing binaries, namely: ASAS 110609 ﹣ 2045.3, ASAS105331 ﹣ 7424.7, and ASAS 130057 + 2120.3. Using the visual (V)-band data obtained from the ASAS catalogue, the orbital and physical parameters of the systems were derived for the first time using the Wilson-Divenney (WD) codes. Our investigation revealed that ASAS 110609 ﹣ 2045.3 is a near-contact binary star of the W Uma type having an angle of inclination of 80° ± 1, a mass ratio of about 0.5, an orbital period of 0.2933 ± 0.0130 days, and an effective temperature in the range of 5800 K - 6200 K, making it a G2V-F7V spectral system. ASAS 105331 ﹣ 7424.7 was established to be an over-contact binary system of the W Uma type, inclined at 86° ± 2 to the line of sight, having a mass ratio of about 0.9, a period of 0.4825 ± 0.0002, and an effective temperature in the range of 5200 K - 5300 K, making it a K2V-K0V spectral system. A third light factor of just 0.1 was established for the system, however, no evidence of starspots or discs was inferred for either component. ASAS 130,057 + 2120.3 is a W Uma binary having a mass ratio of about 0.6 in a state of marginal contact. Its orbital inclination is 55° ± 1;the effective temperature is in the range of 6200 K - 6500 K, making it a F7V-F5V stellar system. The system showed evidence of third light, with a third light factor of 0.6, however, the presence of spots or discs could not be established for either component. The deduced period was 0.8930 ± 0.0014 days. None of the systems showed any evidence of the O’Connell effect on either component.展开更多
基金operated by the Association of Universities for Research in Astronomy,Inc.,under NASA contract NAS5-26555provided by the NASA Office of Space Science via grant NNX13AC07Gthe financial support of her PhD scholarship,held at Queen Mary University of London。
文摘We wrote and used an automated flare detection Python script to search for super-flares on main sequence stars of types A,F,G,K and M in Kepler's long-cadence data from Q0 to Q17.We studied the statistical properties of the occurrence rate of super-flares.For the G-type data set,we compared our results with the previous results of Okamoto et al.by splitting the data set into four rotational bands.We found similar power-law indices for the flare frequency distribution.Hence,we show that inclusion of a high-pass filter,sample biases,gyrochronology and completeness of flare detection is of no significance,as our results are similar to those of Okamoto et al.We estimated that a super-flare on G-type dwarfs with energy of 10^(35) erg occurs on a star once every 4360 yr.We found 4637 super-flares on 1896 G-type dwarfs.Moreover,we identified 321,1125,4538 and 5445 super-flares on 136,522,770 and 312 dwarfs of types A,F,K and M,respectively.We ascertained that the occurrence rate(dN/dE)of super-flares versus flare energy,E,shows a power-law distribution with dN/dE∝E^(-α),whereα■2.0 to 2.1 for the spectral types from F-type to M-type stars.In contrast,the obtainedα■1.3 for A-type stars suggests that the flare conditions differ from those of the other spectral-type stars.We note an increase in flare incidence rate in F-type to M-type stars and a decrease in A-type to F-type stars.
文摘We present the results of our study of three previously unstudied short-period eclipsing binaries, namely: ASAS 110609 ﹣ 2045.3, ASAS105331 ﹣ 7424.7, and ASAS 130057 + 2120.3. Using the visual (V)-band data obtained from the ASAS catalogue, the orbital and physical parameters of the systems were derived for the first time using the Wilson-Divenney (WD) codes. Our investigation revealed that ASAS 110609 ﹣ 2045.3 is a near-contact binary star of the W Uma type having an angle of inclination of 80° ± 1, a mass ratio of about 0.5, an orbital period of 0.2933 ± 0.0130 days, and an effective temperature in the range of 5800 K - 6200 K, making it a G2V-F7V spectral system. ASAS 105331 ﹣ 7424.7 was established to be an over-contact binary system of the W Uma type, inclined at 86° ± 2 to the line of sight, having a mass ratio of about 0.9, a period of 0.4825 ± 0.0002, and an effective temperature in the range of 5200 K - 5300 K, making it a K2V-K0V spectral system. A third light factor of just 0.1 was established for the system, however, no evidence of starspots or discs was inferred for either component. ASAS 130,057 + 2120.3 is a W Uma binary having a mass ratio of about 0.6 in a state of marginal contact. Its orbital inclination is 55° ± 1;the effective temperature is in the range of 6200 K - 6500 K, making it a F7V-F5V stellar system. The system showed evidence of third light, with a third light factor of 0.6, however, the presence of spots or discs could not be established for either component. The deduced period was 0.8930 ± 0.0014 days. None of the systems showed any evidence of the O’Connell effect on either component.
