New light curve analysis and period changes of the HW Vir-type binary system V1828 Aql

Abstract

The new BVRI photometric observations of the HW Vir-type eclipsing binary system V1828 Aql (P = 0.11037399 days) were presented. From these measurements, 16 new eclipse times have been obtained. The light curves in BVRI colors and the radial curves were simultaneously analyzed by using the Wilson–Devinney method for the system parameters. The system consists of a very hot primary component (T1 = 42000 K) and a cold secondary component (T2 = 3077 ± 250 K). The absolute dimensions were found as follows: (M1 = 0.351 ± 4 0.040 M⊙, M2 = 0.095 ± 0.011 M⊙, R1 = 0.176 ± 0.007 R⊙, R2 = 0.140 ± 0.007 R⊙, L1 =86.91 ± 6.76 L⊙ and L2 = 0.002 ± 0.001 L⊙). The orbital period variation of V1828 Aql was made using all available light minimum times. From the (O - C) diagram, the orbital period shows a variation possibly attributable to the light travel time effect by the presence of the third body. The third body orbital period is P3 = 3317.7−17.2+18.9 days, its minimal mass is M3 = 13.24−0.14+0.13 Mj. The mass value calculated for the third body shows, that this object is right at the border between the planets and the brown dwarfs.