Photometric Investigation Research Articles

The HST Large Programme on ω Centauri

We present a study of the white dwarf (WD) cooling sequence (CS) in the globular cluster (GC) Omega Centauri (or NGC 5139; hereafter, ω Cen), the primary goal of a dedicated Hubble Space Telescope (HST) programme. We find that the peak at the termination of the WD CS is located at mF606W = 30.1 ± 0.2 (equivalent to V ∼ 31). The brighter part of ω Cen’s WD CS is consistent with the presence of massive He-core WDs, in agreement with previous HST analyses with ultraviolet and blue filters. Comparative analyses of the WD luminosity function (LF) and theoretical counterparts show that a single-age population for the cluster is compatible with the data. However, an analysis of only the WD LF cannot entirely exclude the possibility of an age range, due to uncertainties in the present-day WD mass function, with a star formation history potentially spanning up to 5 billion years, predominantly comprising stars about 13 Gyr old, with a minority potentially as young as 8 Gyr. This underscores the need for global spectroscopic and photometric investigations that simultaneously include both the WD populations and the previous evolutionary phases, in order to fully understand the cluster’s diverse chemical compositions and ages.

A statistical approach to polarimetric and photometric investigation of the intermediate-age open cluster NGC 1912

ABSTRACT This paper presents a comprehensive multiwavelength investigation of the intermediate-age open cluster NGC 1912. We identified 401 member stars for NGC 1912 using K-nearest neighbour and Gaussian Mixture Model machine learning techniques. The fundamental parameters determined for the cluster are metallicity (z) = 0.0141 $\pm$ 0.0006, log(age) = 8.519 $\pm$ 0.040, binary fraction ($b_{\text{frac}}$) = 0.445 $\pm$ 0.035, visual extinction ($A_V$) = 0.864 $\pm$ 0.033 mag, total-to-selective extinction ratio ($R_V$) = 3.007 $\pm$ 0.096, distance = 1096 $\pm$ 15 pc. The central density ($\rho _o$), core radius ($r_c$), tidal radius ($r_t$), and background density ($\rho _{\mathrm{bg}}$) for the cluster are obtained as 0.643 $\pm$ 0.067 stars arcmin$^{-2}$, 7.743 $\pm$ 0.784 arcmin, 84.633 $\pm$ 7.188 arcmin, and 0.001 $\pm$ 0.000 stars arcmin$^{-2}$, respectively. Dynamical mass segregation study revealed a concentration of some apparently massive stars towards the cluster centre. Polarimetric analysis of 90 stars in $BVR_cI_c$ wavelength bands revealed that the observed polarization in NGC 1912 is not solely attributed to interstellar dust. The Galactic magnetic field is dominant in this region. Dust grain sizes within the intracluster region are found to be relatively smaller than that of the general ISM. The extinction map revealed the existence of a potential ‘interstellar bubble’ located close to the cluster region. Towards the periphery of the probable bubble region, which displays an ovoid-like geometry, 16 probable young stellar objects have been detected, suggesting the ongoing triggering of secondary star formation events in this region.

Spectroscopic and photometric investigations of the totally eclipsing contact binary V1320 Cas

We analyzed the light curve of the total eclipse contact binary V1320 Cas, obtained reliable photometric solutions, confirmed it to be a W-type contact binary with a mass ratio of 3.404 and a contact degree of 23.9%, a cool spot is discovered on the less massive component. Orbital period analysis indicates that the period of V1320 Cas is decreasing at a rate of dPdt=1.78×10−7 day yr−1, superimposed with a cyclic modulation with a period of 1.425 yr, long-term period decrease may be caused by the combination of mass transfer and angular momentum loss, and the cyclic modulation may be caused by the third companion. Using the photometric solutions and Gaia distance, we calculated the absolute physical parameters and plotted mass-luminosity and mass–radius diagrams to analyze the evolutionary status of V1320 Cas, the more massive component is a main sequence star, while the less massive component has higher luminosity and radius than those of main sequence stars with the same mass. With the decreasing orbital period, the two components of V1320 Cas will be gradually closer, while the binary may evolve toward deep contact.

First Light Curve Analysis of NSVS 8294044, V1023 Her, and V1397 Her Contact Binary Systems

The first photometric light curve investigation of the NSVS 8294044, V1023 Her, and V1397 Her binary systems is presented. We used ground-based observations for the NSVS 8294044 system and Transiting Exoplanet Survey Satellite data for V1023 Her and V1397 Her. The primary and secondary times of minima were extracted from all the data, and, by collecting the literature, a new ephemeris was computed for each system. Linear fits for the O − C diagrams were conducted using the Markov Chain Monte Carlo (MCMC) method. Light curve solutions were performed using the PHysics Of Eclipsing BinariEs Python code and the MCMC approach. The systems were found to be contact binary stars based on the fillout factor and mass ratio. V1023 Her showed the O’Connell effect, and a cold starspot on the secondary component was required for the light curve solution. The absolute parameters of the system were estimated based on an empirical relationship between orbital period and mass. We presented a new T–M equation based on a sample of 428 contact binary systems and found that our three target systems were in good agreement with the fit. The positions of the systems were also depicted on the M–L, M–R, q–L ratio, and M tot–J 0 diagrams in the logarithmic scales.

Photometric and Astrometric investigation of the two open star clusters Stock 3 and Stock 18 using the PPMXL Catalogue

Photometric and Astrometric investigation of the two open star clusters Stock 3 and Stock 18 using the PPMXL Catalogue

The Optical Properties of Galaxy Cluster Abell 2319

The optical photometric and spectroscopic investigations of the massive and merging galaxy cluster Abell 2319 (A2319) are presented here. RTT150 telescope of TÜBİTAK, Antalya, Türkiye used CCD imaging and spectroscopic observations. In this paper, 110 galaxies were determined in A2319 and defined as the magnitudes of the Bessel B and R filters in each cluster member galaxy. Spectral observations were done of the brightest cluster galaxy (BCG) and six additional brilliant galaxies. We estimated the Luminosity Function (LF) of galaxies for each filter. The resulting LF of cluster galaxies for each filter is well-fitted by the Double Schechter function. The best-fit parameter values derived as the characteristic absolute magnitudes are -21.08 ± 0.03, and -20.84 ± 0.01, -21.43 ± 0.02, and -20.54 ± 0.02, and the slopes at the faint end of the LF were -1.34 ± 0.04 and -1.12 ± 0.03, -1.47 ± 0.05 and -1.18 ± 0.03 for B and R filters, respectively.

Global Parameters of Eight W UMa-type Binary Systems

Abstract Multiband photometric investigations for eight binary systems of the W Ursae Majoris-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 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 semimajor axis was updated using a sample consisting of 414 contact binary systems and the Monte Carlo Markov Chain approach. Also, using Machine Learning and the Artificial Neural Network model, the relationship between P–T 1–M 1 was updated for a better estimation of the mass of the primary star.

IP Lyn: A Totally Eclipsing Contact Binary with an Extremely Low Mass Ratio

We present the first photometric and orbital period investigations for a neglected totally eclipsing contact binary IP Lyn. The photometric solutions derived from both ground-based and several surveys’ observations suggest that it is a shallow contact binary with an extremely low mass ratio of 0.055. The weak asymmetry observed in our multiple band light curves can be interpreted as a result of an active cool spot on the primary. The absolute physical parameters were determined with the Gaia-distance-based method and checked by an empirical relation. Combining the eclipse timings collected from the literature and those derived from our and variable surveys’ observations, we find that IP Lyn has been undergoing a secular orbital period increase for the past two decades, implying a mass transfer from the less massive secondary to the primary. By comparing the current parameters with the critical instability ones, we infer that IP Lyn is currently stable in spite of its relatively low mass ratio and orbital angular momentum. Finally, from a catalog of 117 extremely low mass ratio contact binaries, we find that their orbital angular momenta are significantly lower than those of the contact binaries with a relatively high mass ratio, suggesting they should be at the late evolutionary stage of a contact binary.

The broadening of the main sequence in the open cluster M38

Abstract Our recent multi-band photometric study of the colour width of the lower main sequence of the open cluster M37 has revealed the presence of a sizeable initial chemical composition spread in the cluster. If initial chemical composition spreads are common amongst open clusters, this would have major implications for cluster formation models and the foundation of the chemical tagging technique. Here we present a study of the unevolved main sequence of the open cluster M38, employing Gaia DR3 photometry and astrometry, together with newly acquired Sloan photometry. We have analysed the distribution of the cluster’s lower main sequence stars with a differential colour-colour diagram made of combinations of Gaia and Sloan magnitudes, like in the study of M37. We employed synthetic stellar populations to reproduce the observed trend of M38 stars in this diagram, and found that the observed colour spreads can be explained simply by the combined effect of differential reddening across the face of the cluster and the presence of unresolved binaries. There is no need to include in the synthetic sample a spread of initial chemical composition as instead necessary to explain the main sequence of M37. Further photometric investigations like ours, as well as accurate differential spectroscopic analyses on large samples of open clusters, are necessary to understand whether chemical abundance spreads are common among the open cluster population.

The first photometric, period variation, and flare activity studies of TIC 24233294: Reviewing with the latest results of well-studied late-type active binaries

In the current study, we present the first photometric, period variation, and flaring activity investigations of TIC 24233294. Additionally, we also review and report the flaring activity of five well-studied eclipsing binaries BX Tri, V405 And, GJ 3236, Thor 42, and GU Boo. Using the Transiting Exoplanet Survey Satellite (TESS) data, continuous variations in the light curves of binaries TIC 24233294, and BX Tri are analysed and presented. The primary and secondary components of all the six binaries in the study are M-type dwarfs. All these binaries are observed to be in detached/semi-detached configuration. Photometric analysis on TIC 24233294 and BX Tri was carried out using the Wilson–Devinney program. The long-term orbital period changes are analyzed and presented, on the basis of photometric solutions and the evolutionary status of the binary systems in the study. Flares are observed to be common in stars with outer convection zones. We identified flares on all binaries in the study and calculated their characteristic parameters like amplitudes, frequency, duration, and energies. Many superflares and few hyperflares were identified in the list of flares detected within the energy range of 1033-1037 erg. The flare events in the binaries could be related to the strong tidal interactions between the components of the binaries and fully/deeper convective interiors.

First Detailed Photometric Investigation on the Nature of Contact Binary System AA Cet

The TESS light curve (LC) of the marginal contact binary AA Cet was analyzed simultaneously with the radial velocity and the orbital period (OP) change of the system was investigated. The physical parameters of the system were obtained by analyzing the LC of AA Cet with the Wilson-Devinney method, and the absolute parameters of the components were calculated using the results obtained. For the components of AA Cet, the masses and radii were calculated as M 1 = 1.39 ± 0.04 M ⊙, M 2 = 0.48 ± 0.02 M ⊙ and R 1 = 1.64 ± 0.03 R ⊙, R 2 = 1.01 ± 0.04 R ⊙, respectively. AA Cet is a marginal contact binary with a temperature difference of 1305 K between its components. A total of 14 eclipse times were obtained from the TESS data and used in the OP analysis together with those collected from the literature. It has been observed that the change in the OP of AA Cet is in the form of a decreasing parabola. Conservative mass transfer between the components has been interpreted as the reason for this change. The OP decrease amount of AA Cet was obtained as dP/dt = 0.0062 ± 0.0006 s yr−1, and the reason for this decrease was attributed to a 3.3(9) × 10−8 M ⊙ mass transfer per year from the more massive component to the less massive one. The age of AA Cet has been estimated as 7 Gyr, as the age of contact systems helps us to understand their evolution.

The First Photometric and Spectroscopic Studies of ASASSN-V J015428.67+204247.2 and its Relation to the Population of Low Mass Ratio Contact Binaries

We performed photometric, spectroscopic and orbital period investigations of ASASSN-V J015428.67+204247.2 (hereafter, J015428) for the first time. The light curves of VRI bands were obtained. Through the analysis of Wilson–Devinney program, J015428 was found as an A-subtype medium contact binary system with a low-mass ratio (q = 0.129, f = 26.8%). The atmospheric parameters were determined in spectroscopic analysis. In the orbital period investigations, we found that the orbital period of J015428 decreases at the rate of −7.13 × 10−8 day yr−1. And the long-term orbital period decrease is possibly due to angular momentum loss (AML). The absolute parameters was calculated with the photometric solutions and Gaia distance. Through the analyses of mass–radius and mass–luminosity diagrams of 54 contact binaries with the low mass ratios (0.096 ≤ q ≤ 0.15), the evolutionary states of low mass ratio binaries were investigated. The results by analyzing the energy transfer parameter indicated that energy transfer rate was a function of mass and bolometric luminosity ratio. We estimated the initial masses and the densities of two components and the age of the binary. The analysis of the orbital angular momentum supposed that J015428 may evolved from a short-period detached binary by AML. J015428 is in a stable contact stage at present.

WISE J141530.7+592234: A Very Low Mass Ratio Contact Binary with Significant Light Curve Variations

Multi-band photometric observations and period investigations of the total eclipsing binary WISE J141530.7+592234 (hereinafter J141530), whose mass ratio close to the low mass ratio limit, were carried out for the first time. The stellar atmospheric parameters of the primary component were calculated by the spectral fitting, yielding the following results: T eff = 5890 ± 22 K, [Fe/H] = 0.01 ± 0.03 dex, log g = 4.53 ± 0.04 cm s−2. Our observations show that the light curve of V-band on May 2 is about 0.1 mag brighter than that observed in February and March at phase 0.6. Comparing with the small amplitude (about 0.2 mag), the variations are remarkable. Meanwhile, obvious light curve variations and quick reversal of O’Connell effects are found in Transiting Exoplanet Survey Satellite data, which is likely caused by magnetic activity. Photometric solutions derived from multi-band light curves indicate that J141530 has a high contact degree (f ∼ 70%) and a very low mass ratio (q ∼ 0.0546). Based on the O − C diagram, a long-term period increase was found. The period increase rate is calculated to be dP/dt = 3.90 × 10−7 day yr−1, which can be explained by mass transfer from the low mass component to the large mass component. By analyzing the merging criterion, such as the ratio of spin angular momentum (J spin) to the orbital angular momentum (J orb), the instability separation and the instability mass ratio, J141530 can be regarded as a potential progenitor of luminous red novae.

The Effect of a Plasma Treatment on the Aging Behavior of Selected Artist Colorants

ABSTRACT In this research study, the effects of an atmospheric pressure plasma treatment on the stability of selected colorants (pigments: red lead, vermilion, azurite, verdigris, smalt, ultramarine, raw sienna, vine black, champagne chalk, Bolognese chalk; dye: alizarin red) were investigated. In order to gain knowledge about the effect of a plasma on the more stable part of colorant-binder systems in works of art, binder-free colorants were first investigated. For this purpose, the samples were briefly exposed to an atmospheric pressure argon or air plasma and then stored for several weeks in two different climates: an indoor climate and a humid climate. Slight color changes were recorded in red lead, verdigris, alizarin red, and Bolognese chalk by photometric investigations and evaluation of the color values in the CIEL*a*b* system. Scanning electron microscopy revealed morphological changes in the plasma-treated verdigris samples. With the help of infrared spectroscopy and X-ray diffractometry, it could be shown that the degradation processes of some of the examined colorants were influenced by the preceding plasma treatment. Nonetheless, atmospheric pressure plasma treatment could be of interest in art restoration as a tool for decontamination and surface activation.

New Photometric Investigations of G-type Contact Binary TU Boo

Two sets of CCD photometric observations for contact binary TU Boo were obtained in 2020 and 2021. Different from its asymmetric light curves published from the literature, our BVR c I c -band curves show that the heights of maximum are almost equal. These distortions of light curves possibly indicate that the components were active in past 25 yr, but they were stable in the last two years. For total-eclipse binary TU Boo, due to some star-spots on the surface of the components, the physical structure obtained by many investigators are different. Therefore, the symmetric multi-color light curves in 2020, 2021 are important for understanding configuration and evolution of this system. By using the Wilson–Devinney program, it is confirmed that TU Boo is an A-type shallow-contact binary with the temperature difference of ΔT = 152 K and fill-out of f = 14.67%. In the O−C diagram of orbital period analysis, a cyclic oscillation superimposed on a continuous decrease was determined. The long-term decreasing is often explained by the mass transfer from the more massive star to less massive one, this system will evolve into a deeper contact binary with time. The cyclic oscillations computed from much more CCD times of light minimum maybe result from the light-travel time effect via the presence of a third body. These characters of structure, evolution and ternary belong to typical A-type W UMa binaries with spectral G.

Synthesis, luminescence and photometric investigation of Sr2B2O5:Dy3+ phosphor for UV-based white LEDs

Synthesis, luminescence and photometric investigation of Sr2B2O5:Dy3+ phosphor for UV-based white LEDs

Semi-detached Algol type binaries with increasing orbital periods: Case studies of BD Vir, BO Gem, DG Lac, RW Cet, and RX Hya

This paper presents results from photometric investigations of five semi-detached binaries. Using the TESS and KEPLER (K2) databases, light curves of classical Algol systems BD Vir, BO Gem, DG Lac, RW Cet, and RX Hya were performed in detail. As a result of light curve analysis, the basic astrophysical parameters of the systems were estimated. The masses and radii of the primary components were estimated as 1.95(20) M⊙, 2.22(22) M⊙, 1.95(20) M⊙, 1.95(20) M⊙, 1.75(18) M⊙ and 2.29(3) R⊙, 2.21(2) R⊙, 2.09(1) R⊙, 1.86(2) R⊙, 1.79(3) R⊙ for BD Vir, BO Gem, DG Lac, RW Cet, and RX Hya, respectively. Likewise, the masses and radii of the secondary components were estimated as 0.45(4) M⊙, 0.47(4) M⊙, 0.26(2) M⊙, 0.50(5) M⊙, 0.47(2) M⊙ and 2.94(3) R⊙, 3.90(2) R⊙, 2.17(1) R⊙, 1.35(2) R⊙, 2.57(4) R⊙ for BD Vir, BO Gem, DG Lac, RW Cet, and RX Hya, respectively. It was determined that the orbital periods of the BD Vir, BO Gem, DG Lac, RW Cet, and RX Hya increased with rates of 8.4(3), 24.2(8), 8.1(3), 1.3(1) and 12.5(6) s century−1, respectively. In addition, sinusoidal changes were determined in the orbital period analysis and it was discussed that these sinusoidal changes could be caused by possible component(s) or magnetic activity around the binary. The positions of the components of BD Vir, BO Gem, DG Lac, RW Cet, and RX Hya in logTeff−logL and logM−logR diagrams are discussed.

First photometric investigation of OGLE-SMC-ECL-2063: A low-metallicity massive contact binary in the SMC

Abstract Studying massive binaries in different evolution stages or environments may help us to solve the problem of the evolution of massive binaries. The metallicity in the Small Magellanic Cloud (SMC) is much lower than that in our Milky Way, and binaries in the SMC are rarely studied. OGLE-SMC-ECL-2063 is a short-period early-type binary with a period of ${0{_{.}^{\circ}}6317643}$ in the SMC. We use the Wilson–Devinney code to analyze its light curves. The result shows that OGLE-SMC-ECL-2063 is an overcontact binary with a high mass ratio of 0.900 and a fill-out factor of $35.9\%$. The O − C curves of the period of OGLE-SMC-ECL-2063 show a long-term increase with a cyclic oscillation of amplitude A = 0.00503 d and period P3 = 14.80 yr. All the evidence above indicates that OGLE-SMC-ECL-2063 is in the Case A mass transfer evolutionary state. The mass transfer rate $\dot{M}_2 = -5.67 \times 10^{-7} M_{\odot }\:$yr−1 is derived and used to explain the continuous period increase. Because both components of OGLE-SMC-ECL-2063 are early-type stars, the existence of a third body may be the reason for the cyclic change in period. The mass of the third body is derived to be no less than 0.70 M⊙ and the orbital separation to be no more than 13.22 au. Combining the result of light-curve analysis, the third body tends to be a low-mass late-type star. Such high-mass-ratio binaries play an important role in the evolution of early-type binaries. Thus, researching OGLE-SMC-ECL-2063 provides the basis for us to study the formation and evolution of early-type contact binaries.

Insight into triglyceride-reducing potential of quercetin in blood plasma environment

Nowadays, hyperlipidemia and abnormal triglyceride levels are global problems menacing human health worldwide. The objective of this study is in-vitro reduction of plasma triglyceride level of the human blood using quercetin through batch adsorption, process optimization, and enzyme-based photometric investigations. The molecular dynamic simulation was also employed to study the peroxidase inhibition effects of quercetin through the enzymatic assay. The best response to the objective function (final triglyceride concentration in the range of 120–170 mg/dl) was obtained at the optimal conditions i.e., contact time of 63 ± 2 min, shaking rate of 264 ± 0.2 rpm and adsorbent dose of 0.037 ± 0.001 g, using experimental design, response surface methodology. Optimization results indicated that quercetin dosage is the most important variable affecting triglyceride removal. Various adsorption isotherms and kinetic models were evaluated to describe the adsorption process. Langmuir type II and Freundlich isotherms as well as pseudo-second-order kinetic model fitted the experimental data appropriately. Based on inhibitory studies and molecular dynamic simulations, quercetin might adsorb plasma triglycerides and inhibit peroxidase enzyme.

High-precision abundances of first-population stars in NGC 2808: confirmation of a metallicity spread

Photometric investigations have revealed that Galactic globular clusters (GCs) exhibit internal metallicity variations amongst the so-called first-population stars, which until now were considered to have a homogeneous initial chemical composition. This is not fully supported by the sparse spectroscopic evidence, which so far gives conflicting results. Here, we present a high-resolution re-analysis of five stars in the Galactic GC NGC 2808 taken from the literature. Target stars are bright red giants with nearly identical atmospheric parameters belonging to the first population according to their identification in the chromosome map of the cluster, and we measured precise differential abundances for Fe, Si, Ca, Ti, and Ni to the ∼0.03 dex level. Thanks to the very small uncertainties associated with the differential atmospheric parameters and abundance measurements, we find that target stars span a range of iron abundance equal to 0.25 ± 0.06 dex. The individual elemental abundances are highly correlated with the positions of the stars along the extended sequence described by first-population objects in the cluster chromosome map: bluer stars have a lower iron content. This agrees with inferences from the photometric analysis. The differential abundances of all other elements also show statistically significant ranges that point to intrinsic abundance spreads. The Si, Ca, Ti, and Ni variations are highly correlated with iron variations and the total abundance spreads for all elements are consistent within the error bars. This suggests a scenario in which short-lived massive stars exploding as supernovae contributed to the self-enrichment of the gas in the natal cloud while star formation was still ongoing.