Four New Eclipsing Binary Systems in the TESS field: CD-34 13220, HD 295082, TYC 6484–426–1 and TYC 6527–2310–1

We present the first evidence for the binarity of four targets in the TESS field. The temperatures are estimated by SED analysis and the orbital periods are determined. The TESS light curves of the systems are analyzed and the orbital and the absolute parameters are derived. The targets are also compared to well-studied binary systems with the same morphological type and their evolutionary states are discussed. Our results indicate that the stars belong to the class of eclipsing detached binary systems.

New photometric studies for two deep, low-mass ratio overcontact binaries: Y Sex and V1363 Ori

We present new photometry for two contact binaries, Y Sex and V1363 Ori, which were observed by three small telescopes in China. By using the W-D method, the absolute parameters are updated from new BVR light curves and previous radial velocity curves. Results identify that two binaries are deep, low-mass ratio (DLMR) overcontact binaries with q ⩽ 0.25 and f ⩾ 50%. From the temperature-luminosity diagram, the primary components are slightly evolved main-sequence stars, whose evolutionary ages are ∼2.51 Gyr for Y Sex and ∼3.56 Gyr for V 1363 Ori, respectively. From the (O − C) curves, it is found that the orbital periods may be undergoing secular increase with cyclic variations, which may be interpreted either by magnetic activity cycles or by the light-time orbit effect. With period increasing, this kind of DLMR overcontact binaries, such as Y Sex and V1363 Ori, will evolve into the rapid-rotating single stars.

Absolute parameters of young stars: PU Pup

We present combined photometric and spectroscopic analyses of the southern binary star PU Pup. High-resolution spectra of this system were taken at the University of Canterbury Mt. John Observatory in the years 2008 and again in 2014–2015. We find the light contribution of the secondary component to be only ∼2% of the total light of the system in optical wavelengths, resulting in a single-lined spectroscopic binary. Recent TESS data revealed grazing eclipses within the light minima, though the tidal distortion, examined also from Hipparcos data, remains the predominating light curve effect. Our model shows PU Pup to have the more massive primary relatively close to filling its Roche lobe. PU Pup is thus approaching the rare ‘fast phase’ of interactive (Case B) evolution. Our adopted absolute parameters are as follows: M 1 = 4.10 (±0.20) M ⊙, M 2 = 0.65 (±0.05) M ⊙, R 1 = 6.60 (±0.30) R ⊙, R 2 = 0.90 (±0.10) R ⊙; T 1 = 11500 (±500) K, T 2 = 5000 (±350) K; photometric distance = 186 (±20) pc, age = 170 (±20) Myr. The less-massive secondary component is found to be significantly oversized and overluminous compared to standard main sequence models. We discuss this discrepancy referring to heating from the reflection effect.

Algorithm for constructing a route to pass a narrow fairway

Modern navigation systems often employ the algorithms for plotting lines for the preliminary route construction. The current conditions of technological development imply the simplicity of constructing routes. However, the most important part was and remains the speed of the system that generates the route. The authors of the paper proposed a universal algorithm for constructing a navigation route in narrow channels of the sea. The presented algorithm identifies the middle of the fairway as the safest point at each narrow segment and connects them with track lines. The problem that can arise is smoothing, as the middle of the fairway can shift significantly. To solve this problem, new relative and absolute parameters that characterize plotting of turning points were introduced. In addition, a unified universal formula was proposed for finding the coordinates of these points on a line perpendicular to the current route of the vessel. It was experimentally proved that correctly selected empirical parameters enable the algorithm to quickly construct a route in any navigation area with a relatively low computational complexity. This approach is appropriate for clearly delineated zones of the fairway, and it is compatible with zone methods.

Absolute Parameters of Young Stars: V Puppis

New spectrometric data on V Pup are combined with satellite photometry (HIPPARCOS and recent TESS) to allow a revision of the absolute parameters with increased precision. We find: M1 = 14.0±0.5, M2 = 7.3±0.3 (M⊙); R1 = 5.48±0.18, R2 = 4.59±0.15 (R⊙); T1 26000±1000, T2 24000 ±1000 (K), age 5 ±1 (Myr), photometric distance 320 ±10 (pc). The TESS photometry reveals low-amplitude (∼0.002 mag) variations of the β Cep kind, consistent with the deduced evolutionary condition and age of the optical primary. This fact provides independent support to our understanding of the system as in a process of Case A type interactive evolution that can be compared with μ1 Sco. The ∼10 M⊙ amount of matter shed by the over-luminous present secondary must have been mostly ejected from the system rather than transferred, thus taking angular momentum out of the orbit and keeping the pair in relative close proximity. New times of minima for V Pup have been studied and the results compared with previous analyses. The implied variation of period is consistent with the Case A evolutionary model, though we offer only a tentative sketch of the original arrangement of this massive system. We are not able to confirm the previously reported cyclical variations having a 5.47 yr period with the new data, though a direct comparison between the HIPPARCOS and TESS photometry points to the presence of third light from a star that is cooler than those of the close binary, as mentioned in previous literature.