We present photometric analysis of the two W UMa type binaries identified in the field of distant open star cluster NGC 6866. Although these systems, namely ID487 and ID494, were reported by Joshi et al., a detailed s...We present photometric analysis of the two W UMa type binaries identified in the field of distant open star cluster NGC 6866. Although these systems, namely ID487 and ID494, were reported by Joshi et al., a detailed study of these stars has not been carried out before. The orbital periods of these stars are found to be 0.415110±0.000001 day and 0.366709±0.000004 day, respectively. Based on the photometric and infrared colors, we find their respective spectral types to be K0 and K3. The photometric light vari- ations of both stars show the O＇Connell effect which can be explained by employing a dark spot on the secondary components. The V and I band light curves are analyzed using the Wilson-Devinney （WD） code and relations given by Gazeas which yield radii and masses for the binary components of star ID487 of R1 = 1.24 ± 0.01R,R2 = 1.11 4- 0.02Re, and M1 = 1.24 ± 0.02Me, M2 = 0.96 ±0.05Me and for star ID494 of R1 = 1.22 ± 0.02Re, R2 = 0.81 4- 0.01 Re, and M1 = 1.20 4- 0.06 Me, M2 = 0.47 4- 0.01 Me.展开更多
In this paper, we study the age and spatial distributions of Cepheids in the Small Magellanic Cloud （SMC） as a function of their ages using data from the OGLE III photometric catalogue. A period - age relation deriv...In this paper, we study the age and spatial distributions of Cepheids in the Small Magellanic Cloud （SMC） as a function of their ages using data from the OGLE III photometric catalogue. A period - age relation derived for Classical Cepheids in the Large Magellanic Cloud （LMC） has been used to find the ages of Cepheids. The age distribution of the SMC Classical Cepheids is found to have a peak at log（Age） ： 8.40 ± 0.10 which suggests that a major star formation event might have occurred in the SMC about 250 4- 50 Myr ago. It is believed that this star forming burst had been triggered by close interactions of the SMC with the LMC and/or the Milky Way. A comparison of the observed spatial distributions of the Cepheids and open star clusters has also been carried out to study the star formation scenario in the SMC.展开更多
基金financial support from the project DST/INT/SA/P-02RJ acknowledges the financial support from the project UGC-BSR research Start-Up Grant Sanctioned vide UGC Order No.F.30-108/2015(BSR)of UGC,under which part of the work has been carried out
文摘We present photometric analysis of the two W UMa type binaries identified in the field of distant open star cluster NGC 6866. Although these systems, namely ID487 and ID494, were reported by Joshi et al., a detailed study of these stars has not been carried out before. The orbital periods of these stars are found to be 0.415110±0.000001 day and 0.366709±0.000004 day, respectively. Based on the photometric and infrared colors, we find their respective spectral types to be K0 and K3. The photometric light vari- ations of both stars show the O＇Connell effect which can be explained by employing a dark spot on the secondary components. The V and I band light curves are analyzed using the Wilson-Devinney （WD） code and relations given by Gazeas which yield radii and masses for the binary components of star ID487 of R1 = 1.24 ± 0.01R,R2 = 1.11 4- 0.02Re, and M1 = 1.24 ± 0.02Me, M2 = 0.96 ±0.05Me and for star ID494 of R1 = 1.22 ± 0.02Re, R2 = 0.81 4- 0.01 Re, and M1 = 1.20 4- 0.06 Me, M2 = 0.47 4- 0.01 Me.
基金Indian Academy of Sciences(IASc),Bangalore for the financial assistance provided through the IAS-SRFP 2014the grant received under the Indo-Russian project INT/RUS/RFBR/P-219 funded by Department of Science and Technology,New Delhi
文摘In this paper, we study the age and spatial distributions of Cepheids in the Small Magellanic Cloud （SMC） as a function of their ages using data from the OGLE III photometric catalogue. A period - age relation derived for Classical Cepheids in the Large Magellanic Cloud （LMC） has been used to find the ages of Cepheids. The age distribution of the SMC Classical Cepheids is found to have a peak at log（Age） ： 8.40 ± 0.10 which suggests that a major star formation event might have occurred in the SMC about 250 4- 50 Myr ago. It is believed that this star forming burst had been triggered by close interactions of the SMC with the LMC and/or the Milky Way. A comparison of the observed spatial distributions of the Cepheids and open star clusters has also been carried out to study the star formation scenario in the SMC.
