New ephemeris of two W Uma-type binaries: BQ Ari and V1370 Tau

International audienceThe new light curve and ephemeris of two eclipsing binary systems BQ Ari and V1370 Tau are presented. The observation was made with CCD through C filter and we used the Czech astronomical society's database to extract raw data, to obtain the time of minimums we used Table Curve software and then calculate O-C with the new ephemeris

A New Look at the YY CrB Binary System

This study presented a new analysis for the TESS-observed W Ursae Majoris (W UMa) binary star YY Coronea Borealis (YY CrB). The light curve was analyzed by the PHysics Of Eclipsing BinariEs (PHOEBE) Python version together with the Markov chain Monte Carlo (MCMC) method. The light curve solutions required a hot spot and l3. New eclipse times from the TESS observations were extracted, and the O-C curve of primary and secondary minima showed an anti-correlated manner. In order to study the O-C curve of minima, minima times between 1991 and 2023 were collected. This investigation reported a new linear ephemeris and by fitting a quadratic function to the O-C curve of minima, calculated the orbital period rate of \mathop P\limits^.\approx 5.786*{10^{-8}} day/year. Assuming mass conservation, a mass exchange rate of \mathop{{M_2}}\limits^.=2.472*{10^{-8}} calculated from the more massive component to the less massive one. Then, by using the light travel time function, the possible third body was determined in the binary and derived the mass of the third body as 0.498M_Sun with a period of \simeq 7351.018 days. The O-C curve analysis and the quantity of mass indicate that the presence of a third body is unlikely. This binary is expected to evolve into a broken-contact phase and is a good case to support the thermal relaxation oscillation model.Comment: Accepted by the New Astronomy Journa

Efficient Irrigation for Recreational Turfgrass in New England: Evapotranspiration and Crop Coefficients

As water demand increases it will become more imperative for golf course superintendents, landscape managers, and other industry professionals to improve water use efficiency in the management of recreational turfgrass. Scheduling irrigation according to actual turfgrass evapotranspiration rates (ETT) is an integral component of efficient irrigation practices. Impracticality of field derived ETT for industry use, however, directs the need of weather station derived reference (predicted) evapotranspiration (ET0). To accurately predict (estimate) ETT of turf and other crops, scientifically derived landscape (crop) coefficients (Kc values) are used in conjunction with mathematical models that incorporate local meteorological data. Research is limited, however, in identifying Kc values and subsequent ET0 for turfgrass species selected and maintained under high intensity recreational practices congruent of golf courses and sports fields in the cool-humid northeast climate. Therefore, objectives of this study were to (i) observe and record ETT of three commonly selected recreational turfgrass species; \u27Exacta\u27 Perennial ryegrass (Lollium perenne L.), \u27Touchdown\u27 Kentucky bluegrass (Poa pratensis L.), and \u27Memorial\u27 Creeping bentgrass (Agrostis stolinifera L.) maintained as golf and sports turf, (ii) analyze the impact various management practices (nitrogen fertility and height of cut) have on ETT, (iii) develop accurate Kc values appropriate for use with the recommended FAO 56 Penman-Monteith mathematical model for accurate ET0 of recreational turf maintained in the cool-humid northeast. Four heights of cut (HOC) and two nitrogen fertility rates (N) were evaluated to determine their impact on turfgrass growth and subsequent water use and ETT of three recreational turfgrass species. Golf turf (creeping bentgrass) maintained at a lower height of cut than sports turf exhibited a smaller leaf area component and a significantly lower (20%) ETT. N applied as slow release (82%) throughout the growing season increased ETT by 5%, particularly with perennial ryegrass sports turf. Taller HOC also increased ETT by 10% due to increased leaf area indices and subsequent decreased resistance to ET. Predicted ET0 according to FAO 56 for all three years of the study (79 observations) captured 71% of ETT. Yearly and monthly calculations suggest less variable (cloudy) weather yielded more accurate ET0. Crop coefficient (Kc) values established in conjunction with FAO 56 ET0 ranged from 0.90 to 1.00 for shorter golf course turf (creeping bentgrass), and 1.15 to 1.25 for taller sports turf (Kentucky bluegrass and perennial ryegrass). Results indicate shorter grass exhibits a lower ETT than taller grass due to various factors, and in the case of industry application, FAO 56 ET0 can accurately estimate ETT of recreational turf in the cool-humid northeast when fitted with appropriate Kc values

First Light Curve Study of the Low Mass Contact Binary V0610 Vir

Photometric data were used to perform the first light curve analysis of the V0610 Vir binary system. We extracted the minima from our observations and compiled the literature, which was few in number. Therefore, we performed computations using the reference ephemeris and presented a new ephemeris and O-C diagram with a linear fit. Light curve analysis was performed using the PHOEBE Python code and the Markov chain Monte Carlo (MCMC) approach. The assumption of a cold spot was required due to the asymmetry in the light curve's maxima. The analysis shows that V0610 Vir is a contact binary system with a fillout factor of 0.085, a mass ratio of 0.998, and an inclination of 70.65deg. The absolute parameters of the system were estimated based on the Gaia DR3 parallax method. The results show that the system is a Low-Mass Contact Binary (LMCB) with a total mass lower than 0.8(M_Sun). The location of the stars was shown in the M-L and M-R diagrams.Comment: Submitted to the Open Astronomy Journa

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(...) perca tempo: olhe -ou, ao menos, veja

Global Parameters of Eight W UMa-type Binary Systems

Multiband photometric investigations for eight binary systems of the W Ursae Majoris (W UMa)-type are presented. Six systems are presented for the first time to analyze their light curves. All the analyzed systems have a temperature below 5000 K and an orbital period of less than 0.28 days. We extracted primary and secondary minima from the ground-based observations of these systems. According to a few observations reported in the literature, linear fits were considered in the O-C diagrams, and new ephemerides were presented. Light curve solutions were performed using the PHysics Of Eclipsing BinariEs (PHOEBE) code. The results of the mass ratio and fillout factor indicate that the systems are contact binary stars. Six of them showed the O'Connell effect, and a cold starspot on each companion was required for light curve solutions. Their absolute parameters were estimated and evaluated by two other methods. In this study, the empirical relationship between the orbital period and semi-major axis was updated using a sample consisting of 414 contact binary systems and the Monte Carlo Markov Chain (MCMC) approach. Also, using Machine Learning (ML) and the Artificial Neural Network (ANN) model, the relationship between $P-T_1-M_1$ was updated for a better estimation of the mass of the primary star.Comment: Accepted by the PASP Journa

Financial Inclusion and Access to Higher Education: An Empirical Study of Selected Districts in Eastern Uganda

Access to higher education has continuously been a challenge in Uganda. The research brought out the relationship between financial inclusion and access to higher education. Descriptive survey research design was adopted and the findings established that digital financing eases making deposits in banks, transacting via mobile money and switching from one bank to the other. Students find it easy to deposit tuition in the bank just as they find it easy to access money via mobile money. While financial inclusion makes financial services available in the economy, students, especially those from low-income families find difficulty accessing a wider range of these products, which hinders their access to higher education. The study also establishes that a good number of students fail to meet admission requirements. Since students from low-income families attend high schools of low quality, they have insufficient understanding of some subjects, and thus unable to join higher education. Online registration and payment, students’ decision not to join, peer influence, and rigidity of university programs; are deeply flawed to limit accessing higher education. However, financial services remain accessible to rich individuals who demonstrate ability to pay. The study recommends that the government of Uganda through the concerned ministry should review the implementation of their policies on Students loan scheme and district quota systems. The government should always publish the lists of students admitted to higher education institutions in popular media and newspapers to create awareness to those being admitted to particular institutions. Keywords: Financial Inclusion. Digital Financing, Financial Services, Access to Higher Education, Higher Education Financing DOI: 10.7176/EJBM/12-17-10 Publication date:June 30th 202

Light Curve Analysis of the AP Dor Binary System using Ground-Based and TESS Observations

The short-period AP Dor eclipsing binary's first in-depth and multiband photometric solutions are presented. We made use of our eight nights of ground-based at a southern hemisphere observatory, and twelve sectors of TESS observations. We extracted eight and 1322 minima from our observations and TESS, respectively. We suggested a new linear ephemeris based on the trend of orbital period variations using the Markov chain Monte Carlo (MCMC) approach. The PHysics Of Eclipsing BinariEs (PHOEBE) Python code and the MCMC approach were used for the light curve analysis. This system did not require a starspot for the light curve solutions. We calculated the absolute parameters of the system using Gaia DR3 parallax method. The orbital angular momentum (J_0) of the AP Dor indicates that this system is located in a region of contact binaries. According to our results, this system is an overcontact binary system with a mass ratio of 0.584, a fillout factor of 48\%, and an inclination of 53deg. The positions of AP Dor stars on the Hertzsprung-Russell (HR) diagram are represented.Comment: Accepted by the Research in Astronomy and Astrophysics (RAA) journa