COMMISSIONS 27 AND 42 OF THE IAU INFORMATION BULLETIN ON VARIABLE STARS Number 3875 Konkoly Observatory Budapest 28 April 1993 HU ISSN 0374 - 0676 UBVR PHOTOMETRY OF THE ECLIPSING BINARY DK PERSEI The eclipsing binary DK Per (=28.1940; m=12.3-13.3 pg) was discovered to be a variable by Ahnert et al. (1947). The spectrum of the components was uncertain. In Zakirov's (1990) paper the system was considered to be in the foreground of the open cluster h and chi Per. DK Per was observed with the 60 cm telescope during 1988 on Mt. Maidanak in South Uzbekistan. As a comparison star, BD+57d 555(=HD 14660; V=9.805m; U-B=0.155m; B-V=0.554m; V-R=0.167) was chosen, 67 measurements in U, 80 in B, 83 in each V and R were carried out. According to our estimation the probable error of a single observation of DK Per is 0.008m in V, for U-B=0.012, for B-V=0.010. The light elements of the system (as given in the GCVS) are as follows: Min I=JDH2442492.374+0.898876d x E Our corrected period is P=0.8988796d for the system. The results of our observations are presented in Figure 1 as light and color curves. The photometric characteristics are given in Table 1. Table 1 V U-B B-V V-R Max 11.332 0.265 0.565 0.505 Min I 12.645 0.388 0.788 0.699 Min II 11.489 0.213 0.529 0.477 All light curves of binary were solved by Lavrov's direct method. The results are listed in Table 2. Table 2 U B V R k 0.760+-0.18 0.848+-0.10 0.820+-0.06 0.794+-0.10 r_1 0.331+-0.20 0.370+-0.11 0.352+-0.07 0.357+-0.10 i 86.9d 88.8d 87.3d 86.0d L_1 0.858+-0.37 0.861+-0.17 0.884+-0.11 0.852+-0.14 Table 3 HJD V U-B B-V V-R 2447000+ 375.4737 11.429 0.260 0.559 0.500 378.4362 11.308 0.266 0.563 0.481 379.3772 11.311 0.232 0.567 0.495 379.3855 11.327 0.290 0.543 0.495 379.3904 11.329 0.249 0.562 0.503 380.3973 11.401 0.290 0.564 0.464 381.4424 11.575 0.327 0.493 381.4695 11.375 0.281 0.580 0.485 381.4737 11.375 0.252 0.553 0.489 382.4279 11.357 0.236 0.552 0.526 382.4355 11.327 0.283 0.546 0.516 382.4688 11.342 0.242 0.601 0.519 383.3439 11.336 0.263 0.562 0.490 383.3515 11.334 0.233 0.564 0.491 383.4640 11.315 0.264 0.595 0.513 383.4716 11.301 0.249 0.571 0.518 384.4792 11.430 0.284 0.573 0.482 385.4272 11.489 0.213 0.529 0.477 385.4876 11.403 0.236 0.589 0.494 388.3917 11.467 0.269 0.577 0.489 389.4015 11.515 0.230 0.549 0.505 390.3209 11.780 0.261 0.613 0.537 390.3272 11.873 0.292 0.620 0.537 390.3334 11.981 0.248 0.621 0.566 390.3410 12.170 0.255 0.661 0.596 390.3487 12.353 0.363 0.699 0.643 390.3570 12.540 0.354 0.731 0.587 390.3618 12.620 0.307 0.770 0.654 390.3702 12.640 0.387 0.808 0.702 390.3772 12.552 0.370 0.792 0.706 390.3841 12.377 0.383 0.722 0.678 390.3897 12.199 0.333 0.693 0.599 390.3959 12.102 0.342 0.664 0.615 390.4008 11.998 0.240 0.637 0.585 390.4063 11.904 0.314 0.617 0.566 390.4105 11.821 0.274 0.604 0.534 390.4126 11.734 0.254 0.607 0.525 390.4202 11.714 0.240 0.573 0.527 390.4285 11.563 0.246 0.602 0.511 390.4341 11.546 0.246 0.560 0.492 390.4383 11.486 0.274 0.575 0.503 390.4438 11.456 0.272 0.566 0.493 390.4480 11.428 0.238 0.577 0.500 390.4522 11.396 0.261 0.565 0.522 390.4577 11.401 0.266 0.541 0.481 390.4619 11.380 0.220 0.560 0.520 390.4674 11.367 0.268 0.566 0.482 390.4716 11.377 0.265 0.543 0.467 390.4758 11.372 0.270 0.547 0.524 390.4799 11.370 0.249 0.560 0.512 390.4862 11.365 0.215 0.532 0.519 390.4897 11.375 0.200 0.560 0.497 391.4160 11.319 0.259 0.572 0.484 391.4223 11.324 0.222 0.568 0.468 395.3924 11.366 0.222 0.571 0.501 395.4000 11.351 0.215 0.579 0.516 396.3994 11.346 0.287 0.561 0.510 396.4063 11.341 0.273 0.552 0.514 442.3646 11.350 0.237 0.566 0.505 442.3702 11.343 0.229 0.564 0.458 444.1771 11.353 0.557 0.518 444.1847 11.381 0.554 0.512 444.1917 11.359 0.563 0.508 444.1979 11.388 0.552 0.518 444.2021 11.373 0.563 0.506 444.2049 11.389 0.556 0.508 444.2084 11.392 0.550 0.495 444.2119 11.401 0.562 0.501 445.2688 11.481 0.558 0.507 445.2716 11.452 0.506 447.2042 11.337 0.549 0.528 447.2688 11.325 0.551 0.503 447.4264 11.526 0.548 452.4827 11.340 0.237 0.559 0.459 454.3097 11.356 0.269 0.567 0.483 454.3139 11.331 0.263 0.570 0.493 454.3799 11.325 0.284 0.569 0.502 454.5084 11.336 0.228 0.564 0.510 454.5132 11.341 0.211 0.580 0.518 459.3820 11.319 0.293 0.566 0.481 460.2625 12.336 0.541 0.488 460.3389 11.361 0.536 0.487 460.3438 11.364 0.547 0.499 [FIGURE 1] Figure 1. Light and colour curves of DK Per The mass ratio q=0.68 was obtained from formulae by Kopal (1959). The best combination of M_v, R and M corresponds to B9V+A8IV. Sizes of the Roche lobe for components r_1crit=0.389 and r_2crit=0.324 were obtained from the mass ratio q. These sizes exceed the relative polar radii of the components. Accordingly, DK Per is classified as a detached system, containing a subgiant. MAMNUN M. ZAKIROV ALIBEK A. AZIMOV Ulugh Beg Astronomical Institute Astronomicheskaya 33, Tashkent 700052, Uzbekistan References: Ahnert, P. et al., 1947, VSS, 1, H.2, 47 [BIBCODE 1947VeSon...2...48A ] Kopal, Z., 1959, Close binary systems, 3, London [BIBCODE 1959cbs..book.....K ] Zakirov, M. M., 1990, Kinematika Fiz. Nebesn. Tel., 6, N3,18 [BIBCODE 1990KFNT....6...18Z ]