The shapes and rotation states(periods and pole orientations)of main-belt asteroids are important for understanding their formation and evolution.In order to obtain sufficient photometric data covering different appar...The shapes and rotation states(periods and pole orientations)of main-belt asteroids are important for understanding their formation and evolution.In order to obtain sufficient photometric data covering different apparitions for asteroid(81)Terpsichore,ground-based photometric observations in 2020 and 2021 were carried out.By combining published and newly obtained photometric data,we calculated the shape and spin parameters for(81)Terpsichore using the convex inversion method.With this method,we have derived a best fitted pole orientation—(22.2±_(3.1)^(3.3°),17.5±_(5.5)^(10.8°))with a spin period of 10.94±_(0.01)^(0.01)h.Based on the derived convex shape of(81)Terpsichore,we have fitted the H,G+1,G_(2)phase function using the calibrated TESS data and Gaia data after accounting for the lightcurve amplitude correction.As a result,we have derived its absolute magnitude H=8.68±_(0.19)^(0.22)mag with corresponding phase function parameters G_(1)=0.82±_(0.10)^(0.09)and G_(2)=0.02±_(0.02)^(0.03).展开更多
In this work,we report observations of three comets:38P/Stephan-Oterma,64P/Swift-Gehrels,and C/2017 M4(ATLAS),conducted with the Nanshan one-meter wide-field telescope in 2018 August and November,and 2019January.We ex...In this work,we report observations of three comets:38P/Stephan-Oterma,64P/Swift-Gehrels,and C/2017 M4(ATLAS),conducted with the Nanshan one-meter wide-field telescope in 2018 August and November,and 2019January.We extracted morphological features through image enhancement techniques and calculated the dust activity parameter,Afρ,along with dust mass loss rates and coma color indices using broadband photometric data.Our morphological analysis uncovered a spectrum of dust characteristics among the observed comets,ranging from a significant twisted structure in comet 38P/Stephan-Oterma’s coma to the regular coma envelope surrounding comet 64P/Swift-Gehrels.The Afρvalues varied between 148.8±0.3 cm for 64P/Swift-Gehrels and1118.5±6.2 cm for C/2017 M4(ATLAS)(measured within a reference aperture radius ofρ=6″),indicating a range from moderate to high activity levels.Dust mass loss rates were estimated from 328.1 kg s^(-1)for comet 64P/Swift-Gehrels to 1395.5 kg s^(-1)for comet C/2017 M4(ATLAS).The color indices of comets 38P/Stephan-Oterma and C/2017 M4(ATLAS)closely resemble the average colors of active short-period comets and active longperiod comets,respectively.In contrast,64P/Swift-Gehrels exhibits a significantly bluer hue than typical Jupiter family comets.展开更多
The study reports photometric and spectroscopic observations of two recently recognized contact binary systems.Both systems show total eclipses and analysis of the light curves indicates both have very low mass ratios...The study reports photometric and spectroscopic observations of two recently recognized contact binary systems.Both systems show total eclipses and analysis of the light curves indicates both have very low mass ratios of less than 0.3.We derive absolute parameters from color and distance based calibrations and show that,although both have low mass ratios,they are likely to be in a stable orbit and unlikely to merge.In other respects,both systems have characteristics similar to other contact binaries with the secondary larger and brighter than their main sequence counterparts and we also find that the secondary is considerably denser than the primary in both systems.展开更多
We carried out new photometric observations of asteroid （106） Dione at three apparitions （2004, 2012 and 2015） to understand its basic physical properties. Based on a new brightness model, new photometric observat...We carried out new photometric observations of asteroid （106） Dione at three apparitions （2004, 2012 and 2015） to understand its basic physical properties. Based on a new brightness model, new photometric observational data and published data of （106） Dione were analyzed to characterize the morphology of Dione＇s photometric phase curve. In this brightness model, a cellinoid ellipsoid shape and three-parameter （H, G1, G2） magnitude phase function system were involved. Such a model can not only solve the phase function system parameters of （106） Dione by considering an asymmetric shape of an asteroid, but also can be applied to more asteroids, especially those without enough photometric data to solve the convex shape. Using a Markov Chain Monte Carlo （MCMC） method, Dione＇s absolute magnitude of H = 7.66＋0.03-0.03 mag, and phase function parameters G1 = 0.682＋0.077-0.077 and G2 = 0.081＋0.042-0.042 were obtained. Simultaneously, Dione＇s simplistic shape, orientation of pole and rotation period were also determined preliminarily.展开更多
Multi-color light curves of V1197 Her were obtained with the 2.4 meter optical telescope at the Thai National Observatory and the Wilson-Devinney(W-D)program was used to model the observational light curves.The photom...Multi-color light curves of V1197 Her were obtained with the 2.4 meter optical telescope at the Thai National Observatory and the Wilson-Devinney(W-D)program was used to model the observational light curves.The photometric solutions reveal that V1197 Her is a W-subtype shallow contact binary system with a mass ratio of q=2.61 and a fill-out factor of f=15.7%.The temperature difference between the primary star and secondary star is only 140 K in spite of the low degree of contact,which means that V1197 Her is not only in geometrical contact configuration but is also already under thermal contact status.The orbital inclination of V1197 Her is as high as i=82.7?,and the primary star is completely eclipsed at the primary minimum.The totally eclipsing characteristic implies that the determined physical parameters are highly reliable.The masses,radii and luminosities of the primary star(star 1)and secondary star(star2)are estimated to be M1=0.30(1)M⊙,M2=0.77(2)M⊙,R1=0.54(1)R⊙,R2=0.83(1)R⊙,L1=0.18(1)L⊙and L2=0.38(1)L⊙.The evolutionary statuses of the two component stars are drawn in the Hertzsprung-Russell diagram,showing that the less massive but hotter primary star is more evolved than the secondary star.The period of V1197 Her is decreasing continuously at a rate of d P/dt=-2.58×10^-7 day·year^-1,which can be explained by mass transfer from the more massive star to the less massive one at a rate of dM2/dt=-1.61×10^-7 M⊙year^-1.The light curves of V1197 Her are reported to show the O’Connell effect.Thus,a cool spot is added to the more massive star to model the asymmetry in the light curves.展开更多
The one-meter telescope at Weihai Observatory （WHO） of Shandong University is an f/8 Cassegrain telescope. Three sets of filters are installed in a dual layer filterwheel that use Johnson-Cousins UBVRI, Sloan Digita...The one-meter telescope at Weihai Observatory （WHO） of Shandong University is an f/8 Cassegrain telescope. Three sets of filters are installed in a dual layer filterwheel that use Johnson-Cousins UBVRI, Sloan Digital Sky Survey u′g′r′i′z′ and Stomgren uvby. The photometric system and the CCD camera are introduced, followed by detailed analysis of their performances, and determination of the relevant parameters, including gain, readout noise, dark current and linearity of the CCD cam- era. In addition, the parameters describing the site＇s astro-climate, including typical seeing, statistics on the number of clear nights and average sky brightness, based on data gathered from Sep. 2007 to Aug. 2013, are systematically studied and reported in this work. Photometric calibrations were done using Landolt standard star obser- vations spanning eight nights, which yielded transformation coefficients, photometric precision and system throughput. The limiting magnitudes are simulated using the derived calibration parameters and classic observation conditions at WHO.展开更多
To investigate a huge sample of data related to the Stellar Abundance and Galactic Evolution(SAGE) survey in more detail, we are performing a northern sky photometric survey named SAGES with the SAGE photometric syste...To investigate a huge sample of data related to the Stellar Abundance and Galactic Evolution(SAGE) survey in more detail, we are performing a northern sky photometric survey named SAGES with the SAGE photometric system.This system consists of eight filters: Str?mgren-u, SAGE-v, SDSS g, r, i, DDO-51, Hαwideand Hαnarrow, including three Sloan broadband filters, three intermediateband filters, two narrow-band filters and one newly-designed narrow-band filter.SAGES covers～12 000 square degrees of the northern sky with δ >-5°, excluding the Galactic disk(|b| < 10°) and the sky area 12 h <RA <18 h.The photometric detection limit depth at signal-to-noise ratio 5σ can be as deep as V～20 mag.SAGES will produce a photometric catalog with uniform depth for～500 million stars with atmospheric parameters including effective temperature Teff, surface gravity log g and metallicity[Fe/H], as well as interstellar extinction to each individual target.In this work, we will briefly introduce the SAGE photometric system, the SAGE survey and a preliminary test field of the open cluster NGC 6791 and its surroundings.展开更多
We investigate two training-set methods; support vector machines （SVMs） and Kernel Regression （KR） for photometric redshift estimation with the data from the databases of Sloan Digital Sky Survey Data Release 5 an...We investigate two training-set methods; support vector machines （SVMs） and Kernel Regression （KR） for photometric redshift estimation with the data from the databases of Sloan Digital Sky Survey Data Release 5 and Two Micron All Sky Survey. We probe the performances of SVMs and KR for different input patterns. Our experiments show that with more parameters considered, the accuracy does not always increase, and only when appropriate parameters are chosen, the accuracy can improve. For different approaches, the best input pattern is different. With different parameters as input, the optimal bandwidth is dissimilar for KR. The rms errors of photometric redshifts based on SVM and KR methods are less than 0.03 and 0.02, respectively. Strengths and weaknesses of the two approaches are summarized. Compared to other methods of estimating photometric redshifts, they show their superiorities, especially KR, in terms of accuracy.展开更多
We describe the photometric calibration of the Lunar-based Ultraviolet Telescope（LUT）, the first robotic astronomical telescope working on the lunar surface, for its first six months of operation on the lunar surfac...We describe the photometric calibration of the Lunar-based Ultraviolet Telescope（LUT）, the first robotic astronomical telescope working on the lunar surface, for its first six months of operation on the lunar surface. Two spectral datasets（set A and B） from near-ultraviolet（NUV） to the optical band were constructed with 44 International Ultraviolet Explorer（IUE） standards, because of the LUT＇s relatively wide wavelength coverage. Set A was obtained by extrapolating the IUE NUV spectra（λ 〈 3200 ） to the optical band based upon the theoretical spectra of stellar atmosphere models. Set B was composed of theoretical spectra from 2000 to 8000 extracted from the same model grid. In total, seven standards have been observed in15 observational runs until May 2014. The calibration results show that the photometric performance of LUT is highly stable in its first six months of operation. The magnitude zero points obtained from the two spectral datasets are also consistent with each other, i.e., zp = 17.54 ± 0.09 mag（set A） and zp = 17.52 ± 0.07 mag（set B）.展开更多
This paper reports results from the first long-term BV(RI)c photometric CCD observations of three variable pre-main-sequence stars collected during the period from February 2007 to January 2020. The investigated stars...This paper reports results from the first long-term BV(RI)c photometric CCD observations of three variable pre-main-sequence stars collected during the period from February 2007 to January 2020. The investigated stars are located in the field of the PMS star V733 Cep within the Cepheus OB3 association. All stars from our study show rapid photometric variability in all-optical passbands. In this paper, we describe and discuss the photometric behavior of these stars and the possible reasons for their variability. In the light variation of two of the stars, we found periodicity.展开更多
We carry out a re-analysis of the photometric data in Rclc bands which were taken during the Nainital Microlensing Survey from 1998 to 2002 with the aim to detect gravitational microlensing events in the direction of ...We carry out a re-analysis of the photometric data in Rclc bands which were taken during the Nainital Microlensing Survey from 1998 to 2002 with the aim to detect gravitational microlensing events in the direction of M31. Here, we do photometric analysis of a faint W UMa binary CSS_JO04259.3＋410629 identified in the target field. The orbital period of this star is found to be 0.266402±0.000018 d. The photometric mass ratio, q, is found to be 0.28±0.01. The photometric light curves are investigated using the Wilson-Devinney （WD） code and absolute parameters are determined using empirical relations which provide masses and radii of the binary as M1 = 1.19±0.09M⊙, M2 = 0.33±0.02M⊙ and R1 = 1.02±0.04R⊙, R2 = 0.58±0.08Re respectively based on Rc band data. Quite similar values are found by analyzing/c band data. From the photometric light curve examination, the star is understood to be a low mass-ratio overcontact binary of A-subtype with a high fill-out factor of about 47%. The binary system is found to be located approximately at a distance of 2.64±0.03 kpc having a separation of 2.01 ±0.05 Re between the two components.展开更多
We present photometric analysis of the two W UMa type binaries identified in the field of distant open star cluster NGC 6866. Although these systems, namely ID487 and ID494, were reported by Joshi et al., a detailed s...We present photometric analysis of the two W UMa type binaries identified in the field of distant open star cluster NGC 6866. Although these systems, namely ID487 and ID494, were reported by Joshi et al., a detailed study of these stars has not been carried out before. The orbital periods of these stars are found to be 0.415110±0.000001 day and 0.366709±0.000004 day, respectively. Based on the photometric and infrared colors, we find their respective spectral types to be K0 and K3. The photometric light vari- ations of both stars show the O＇Connell effect which can be explained by employing a dark spot on the secondary components. The V and I band light curves are analyzed using the Wilson-Devinney （WD） code and relations given by Gazeas which yield radii and masses for the binary components of star ID487 of R1 = 1.24 ± 0.01R,R2 = 1.11 4- 0.02Re, and M1 = 1.24 ± 0.02Me, M2 = 0.96 ±0.05Me and for star ID494 of R1 = 1.22 ± 0.02Re, R2 = 0.81 4- 0.01 Re, and M1 = 1.20 4- 0.06 Me, M2 = 0.47 4- 0.01 Me.展开更多
The massive photometric data collected from multiple large-scale sky surveys offer significant opportunities for measuring distances of celestial objects by photometric redshifts. However, catastrophic failure is an u...The massive photometric data collected from multiple large-scale sky surveys offer significant opportunities for measuring distances of celestial objects by photometric redshifts. However, catastrophic failure is an unsolved problem with a long history and it still exists in the current photometric redshift estimation approaches （such as the k-nearest neighbor （KNN） algorithm）. In this paper, we propose a novel two-stage approach by integration of KNN and support vector machine （SVM） methods together. In the first stage, we apply the KNN algorithm to photometric data and estimate their corresponding Zphot. Our analysis has found two dense regions with catastrophic failure, one in the range of Zphot E [0.3, 1.2] and the other in the range of Zphot E [1.2, 2.1]. In the second stage, we map the photometric input pattern of points falling into the two ranges from their original attribute space into a high dimensional feature space by using a Gaussian kernel function from an SVM. In the high dimensional feature space, many outliers resulting from catastrophic failure by simple Euclidean distance computation in KNN can be identified by a classification hyperplane of SVM and can be further corrected. Experimental results based on the Sloan Digital Sky Survey （SDSS） quasar data show that the two-stage fusion approach can significantly mitigate catastrophic failure and improve the estimation accuracy of photometric redshifts of quasars. The percents in different /△z/ ranges and root mean square （rms） error by the integrated method are 83.47%, 89.83%, 90.90% and 0.192, respectively, compared to the results by KNN （71.96%, 83.78%, 89.73% and 0.204）.展开更多
A new analytical method for detecting butyltin in seawater is presented. In this method, the solid phase microextraction technique for pretreatment of the butyltin compound was used and a new type Flame Photometric De...A new analytical method for detecting butyltin in seawater is presented. In this method, the solid phase microextraction technique for pretreatment of the butyltin compound was used and a new type Flame Photometric Detector (FPD) was designed. Use of this method to determine the butyltin contents in Qingdao coast seawater yielded convincing results.展开更多
There are hundreds of welded studs in a car.The posture of a welded stud determines the quality of the body assembly,thus affecting the safety of cars.It is crucial to detect the posture of the welded studs.Considerin...There are hundreds of welded studs in a car.The posture of a welded stud determines the quality of the body assembly,thus affecting the safety of cars.It is crucial to detect the posture of the welded studs.Considering the lack of accurate method in detecting the position of welded studs,this paper aims to detect the weld stud’s pose based on photometric stereo and neural network.Firstly,a machine vision-based stud dataset collection system is built to achieve the stud dataset labelling automatically.Secondly,photometric stereo algorithm is applied to estimate the stud normal map which as input is fed to neural network.Finally,we improve a lightweight YOLOv4 neural network which is applied to achieve the detection of stud position,thus overcoming the shortcomings of traditional testing methods.The research and experimental results show that the stud pose detection system designed achieves rapid detection and high accuracy positioning of the stud.This research provides the foundation combining the photometric stereo and deep learning for object detection in industrial production.展开更多
Eclipsing binary stars with a pulsating component are powerful tools that allow us to probe the stellar interior structure and the evolutionary statuses with a good accuracy. Therefore, in this study, spectroscopic an...Eclipsing binary stars with a pulsating component are powerful tools that allow us to probe the stellar interior structure and the evolutionary statuses with a good accuracy. Therefore, in this study, spectroscopic and photometric examinations of an eclipsing binary system V948 Her are presented. The primary component of the system is classified to be a candidate 3 Scuti variable in the literature. The fundamental stellar, atmospheric and orbital parameters, and the surface abundance of the star were determined and the pulsation behaviour was investigated in this study. The orbital parameters were derived by the analysis of radial velocity and SuperWASP light curves. The spectral classification was found to be F2V. The initial atmospheric parameters of the primary component were derived by analysis of the spectral energy distribution and hydrogen lines. The final atmospheric parameters and chemical abundances of the primary component were obtained by using the method of spectrum synthesis. As a result, the final atmospheric parameters were determined as Teff= 7100±200 K, log 9= 4.34±0.1 cgs and ζ = 2.2 4± 0.2 km s^-1. The surface abundance was found to be similar to solar. The fundamental stellar parameters of both components were also obtained to be M = 1.722 4±0.123, 0.762 4± 0.020 Me, R = 1.655 4± 0.034,M,R= 0.689 ± 0.016 R for primary and secondary components, respectively. The pulsation characteristic of the primary component was examined using SuperWASP data and the pulsation period was found to be ~0.038 d. The position of the primary pulsating component was also obtained inside the instability strip of δ Sct stars. The primary component of V948 Her was defined to be a Sct variable.展开更多
We characterize the morphology of the photometric phase curve model of an asteroid with a three- parameter magnitude phase function H - G1 - G2 system by considering the effect of brightness variation arising from a t...We characterize the morphology of the photometric phase curve model of an asteroid with a three- parameter magnitude phase function H - G1 - G2 system by considering the effect of brightness variation arising from a triaxial ellipsoid representing the asteroid＇s shape. Applying this new model and a Markov Chain Monte Carlo method, we refine the photometric phase curve of asteroid （107） Camilla and obtain its absolute magnitude H = 7.026-0.054^＋0.052 mag, and phase function parameters G1=0.489-0.044^＋0.043 and G2 = 0.259-0.023^＋0.023.Meanwhile, we also determine （107） Camilla＇s orientation of pole （74.1°-4.5°^＋4.3°,50.2°-5.0°^＋5.4°）. with rotational period of 4.843928-0.000001^＋0.000001 h, and axial ratios a/b ： 1.409-0.020^＋0.020 And b/c =1.249-0.060^＋0.063. Furthermore, according to the values of phase function parameters G1 and G2, we infer that asteroid （107） Camilla is an X-type asteroid.展开更多
The main role of water treatment plants is to supply high-quality safe drinking water. Coagulation is one of the most important stages of surface water treatment. The photometric dispersion analyzer(PDA) is a new opti...The main role of water treatment plants is to supply high-quality safe drinking water. Coagulation is one of the most important stages of surface water treatment. The photometric dispersion analyzer(PDA) is a new optical method for flocculation monitoring, and is feasible to realize coagulation feedback control. The on line modification of the coagulation control system' s set point( or optimum dosing coagulant) has influenced the application of this technology in water treatment plant for a long time. A fuzzy control system incorporating the photometric dispersion analyzer was utilized in this coagulation control system. Proposed is a fuzzy logic inference control system by using Takagi and Sugeno' s fuzzy if-then rule for the self-correction of set point on line. Programmed is the dosing rate fuzzy control system in SIEMENS small-scale programmable logic controller. A 400 L/min middle-scale water treatment plant was utilized to simulate the reaction. With the changes of raw water quality, the set point was modified correctly in time, as well as coagulant dosing rate, and residual turbility before filtration was eligible and stable. Results show that this fuzzy inference and control system performs well on the coagulation control system through PDA.展开更多
We present the results of our study of the eclipsing binary systems CSS J112237.1+395219,LINEAR 1286561 and LINEAR 2602707 based on new CCD B,V,Rcand Iccomplete light curves.The ultra-short period nature of these star...We present the results of our study of the eclipsing binary systems CSS J112237.1+395219,LINEAR 1286561 and LINEAR 2602707 based on new CCD B,V,Rcand Iccomplete light curves.The ultra-short period nature of these stars,as reported by Drake et al.,is confirmed and the system’s periods are revised.The light curves were modeled using the 2003 version of the Wilson-Devinney code.When necessary,cool spots on the surface of the primary component were introduced to account for asymmetries in the light curves.As a result,we found that CSS J112237.1+395219 is a W UMa type contact binary system belonging to W subclass with a mass ratio of q=1.61 and a shallow degree of contact of 14.8%where the primary component is hotter than the secondary one by 500 K.LINEAR 1286561 and LINEAR2602707 are detached binary systems with mass ratios q=3.467 and q=0.987 respectively.These detached systems are low-mass M-type eclipsing binaries with similar temperatures.The marginal contact,fill-out factor and temperature difference between components of CSS J112237.1+395219 suggest that this system may be at a key evolutionary state predicted by thermal relaxation oscillation(TRO)theory.From the estimated absolute parameters,we conclude that our systems share common properties with other ultrashort period binaries.展开更多
基金financial support from the Science Research Foundation of Yunnan Education Department of China(grant 2020J0649)the Natural Science Foundation of Yunnan Province(grant 202101AU070010)the financial support from the Hundred Talents Program of Yuxi(grant 2019-003)。
文摘The shapes and rotation states(periods and pole orientations)of main-belt asteroids are important for understanding their formation and evolution.In order to obtain sufficient photometric data covering different apparitions for asteroid(81)Terpsichore,ground-based photometric observations in 2020 and 2021 were carried out.By combining published and newly obtained photometric data,we calculated the shape and spin parameters for(81)Terpsichore using the convex inversion method.With this method,we have derived a best fitted pole orientation—(22.2±_(3.1)^(3.3°),17.5±_(5.5)^(10.8°))with a spin period of 10.94±_(0.01)^(0.01)h.Based on the derived convex shape of(81)Terpsichore,we have fitted the H,G+1,G_(2)phase function using the calibrated TESS data and Gaia data after accounting for the lightcurve amplitude correction.As a result,we have derived its absolute magnitude H=8.68±_(0.19)^(0.22)mag with corresponding phase function parameters G_(1)=0.82±_(0.10)^(0.09)and G_(2)=0.02±_(0.02)^(0.03).
基金supported by the Natural Science Foundation of Xinjiang Uygur Autonomous Region of China(grant No.2021D01B112)Tianshan Talent Training Program through the grant 2023TSYCCX0101。
文摘In this work,we report observations of three comets:38P/Stephan-Oterma,64P/Swift-Gehrels,and C/2017 M4(ATLAS),conducted with the Nanshan one-meter wide-field telescope in 2018 August and November,and 2019January.We extracted morphological features through image enhancement techniques and calculated the dust activity parameter,Afρ,along with dust mass loss rates and coma color indices using broadband photometric data.Our morphological analysis uncovered a spectrum of dust characteristics among the observed comets,ranging from a significant twisted structure in comet 38P/Stephan-Oterma’s coma to the regular coma envelope surrounding comet 64P/Swift-Gehrels.The Afρvalues varied between 148.8±0.3 cm for 64P/Swift-Gehrels and1118.5±6.2 cm for C/2017 M4(ATLAS)(measured within a reference aperture radius ofρ=6″),indicating a range from moderate to high activity levels.Dust mass loss rates were estimated from 328.1 kg s^(-1)for comet 64P/Swift-Gehrels to 1395.5 kg s^(-1)for comet C/2017 M4(ATLAS).The color indices of comets 38P/Stephan-Oterma and C/2017 M4(ATLAS)closely resemble the average colors of active short-period comets and active longperiod comets,respectively.In contrast,64P/Swift-Gehrels exhibits a significantly bluer hue than typical Jupiter family comets.
基金funded by MCIN/AEI/10.13039/501100011033/through grant PID2020-112949GB-100partially updated by using funding from the European Union's Horizon2020 Research and Innovation Programme,under grant Agreement No.776403(EXOPLANETS-A)financial support of the Ministry of Education,Science and Technological Development of the Republic of Serbia through contract No.451-03-9/2021-14/200002。
文摘The study reports photometric and spectroscopic observations of two recently recognized contact binary systems.Both systems show total eclipses and analysis of the light curves indicates both have very low mass ratios of less than 0.3.We derive absolute parameters from color and distance based calibrations and show that,although both have low mass ratios,they are likely to be in a stable orbit and unlikely to merge.In other respects,both systems have characteristics similar to other contact binaries with the secondary larger and brighter than their main sequence counterparts and we also find that the secondary is considerably denser than the primary in both systems.
基金funded by the National Natural Science Foundation of China(Grant Nos.11073051,11473066 and 11673063)the Open Project of Key Laboratory of Space Object and Debris Observation,Chinese Academy of Sciences(title:Photometric study of space debris in near geostationary orbit)
文摘We carried out new photometric observations of asteroid （106） Dione at three apparitions （2004, 2012 and 2015） to understand its basic physical properties. Based on a new brightness model, new photometric observational data and published data of （106） Dione were analyzed to characterize the morphology of Dione＇s photometric phase curve. In this brightness model, a cellinoid ellipsoid shape and three-parameter （H, G1, G2） magnitude phase function system were involved. Such a model can not only solve the phase function system parameters of （106） Dione by considering an asymmetric shape of an asteroid, but also can be applied to more asteroids, especially those without enough photometric data to solve the convex shape. Using a Markov Chain Monte Carlo （MCMC） method, Dione＇s absolute magnitude of H = 7.66＋0.03-0.03 mag, and phase function parameters G1 = 0.682＋0.077-0.077 and G2 = 0.081＋0.042-0.042 were obtained. Simultaneously, Dione＇s simplistic shape, orientation of pole and rotation period were also determined preliminarily.
基金supported by the National Natural Science Foundation of China(Grant Nos.11703080 and11703082)the Yunnan Natural Science Foundation(No.2018FB006)
文摘Multi-color light curves of V1197 Her were obtained with the 2.4 meter optical telescope at the Thai National Observatory and the Wilson-Devinney(W-D)program was used to model the observational light curves.The photometric solutions reveal that V1197 Her is a W-subtype shallow contact binary system with a mass ratio of q=2.61 and a fill-out factor of f=15.7%.The temperature difference between the primary star and secondary star is only 140 K in spite of the low degree of contact,which means that V1197 Her is not only in geometrical contact configuration but is also already under thermal contact status.The orbital inclination of V1197 Her is as high as i=82.7?,and the primary star is completely eclipsed at the primary minimum.The totally eclipsing characteristic implies that the determined physical parameters are highly reliable.The masses,radii and luminosities of the primary star(star 1)and secondary star(star2)are estimated to be M1=0.30(1)M⊙,M2=0.77(2)M⊙,R1=0.54(1)R⊙,R2=0.83(1)R⊙,L1=0.18(1)L⊙and L2=0.38(1)L⊙.The evolutionary statuses of the two component stars are drawn in the Hertzsprung-Russell diagram,showing that the less massive but hotter primary star is more evolved than the secondary star.The period of V1197 Her is decreasing continuously at a rate of d P/dt=-2.58×10^-7 day·year^-1,which can be explained by mass transfer from the more massive star to the less massive one at a rate of dM2/dt=-1.61×10^-7 M⊙year^-1.The light curves of V1197 Her are reported to show the O’Connell effect.Thus,a cool spot is added to the more massive star to model the asymmetry in the light curves.
基金Supported by the National Natural Science Foundation of China
文摘The one-meter telescope at Weihai Observatory （WHO） of Shandong University is an f/8 Cassegrain telescope. Three sets of filters are installed in a dual layer filterwheel that use Johnson-Cousins UBVRI, Sloan Digital Sky Survey u′g′r′i′z′ and Stomgren uvby. The photometric system and the CCD camera are introduced, followed by detailed analysis of their performances, and determination of the relevant parameters, including gain, readout noise, dark current and linearity of the CCD cam- era. In addition, the parameters describing the site＇s astro-climate, including typical seeing, statistics on the number of clear nights and average sky brightness, based on data gathered from Sep. 2007 to Aug. 2013, are systematically studied and reported in this work. Photometric calibrations were done using Landolt standard star obser- vations spanning eight nights, which yielded transformation coefficients, photometric precision and system throughput. The limiting magnitudes are simulated using the derived calibration parameters and classic observation conditions at WHO.
基金supported by the National Natural Science Foundation of China (Grant Nos.11373003, 11673030 and U1631102)the National Key Basic Research Program of China (2015CB857002)National Program on Key Research and Development Project (2016YFA0400804)
文摘To investigate a huge sample of data related to the Stellar Abundance and Galactic Evolution(SAGE) survey in more detail, we are performing a northern sky photometric survey named SAGES with the SAGE photometric system.This system consists of eight filters: Str?mgren-u, SAGE-v, SDSS g, r, i, DDO-51, Hαwideand Hαnarrow, including three Sloan broadband filters, three intermediateband filters, two narrow-band filters and one newly-designed narrow-band filter.SAGES covers～12 000 square degrees of the northern sky with δ >-5°, excluding the Galactic disk(|b| < 10°) and the sky area 12 h <RA <18 h.The photometric detection limit depth at signal-to-noise ratio 5σ can be as deep as V～20 mag.SAGES will produce a photometric catalog with uniform depth for～500 million stars with atmospheric parameters including effective temperature Teff, surface gravity log g and metallicity[Fe/H], as well as interstellar extinction to each individual target.In this work, we will briefly introduce the SAGE photometric system, the SAGE survey and a preliminary test field of the open cluster NGC 6791 and its surroundings.
基金Supported by the National Natural Science Foundation of China.
文摘We investigate two training-set methods; support vector machines （SVMs） and Kernel Regression （KR） for photometric redshift estimation with the data from the databases of Sloan Digital Sky Survey Data Release 5 and Two Micron All Sky Survey. We probe the performances of SVMs and KR for different input patterns. Our experiments show that with more parameters considered, the accuracy does not always increase, and only when appropriate parameters are chosen, the accuracy can improve. For different approaches, the best input pattern is different. With different parameters as input, the optimal bandwidth is dissimilar for KR. The rms errors of photometric redshifts based on SVM and KR methods are less than 0.03 and 0.02, respectively. Strengths and weaknesses of the two approaches are summarized. Compared to other methods of estimating photometric redshifts, they show their superiorities, especially KR, in terms of accuracy.
基金Supported by the National Natural Science Foundation of China
文摘We describe the photometric calibration of the Lunar-based Ultraviolet Telescope（LUT）, the first robotic astronomical telescope working on the lunar surface, for its first six months of operation on the lunar surface. Two spectral datasets（set A and B） from near-ultraviolet（NUV） to the optical band were constructed with 44 International Ultraviolet Explorer（IUE） standards, because of the LUT＇s relatively wide wavelength coverage. Set A was obtained by extrapolating the IUE NUV spectra（λ 〈 3200 ） to the optical band based upon the theoretical spectra of stellar atmosphere models. Set B was composed of theoretical spectra from 2000 to 8000 extracted from the same model grid. In total, seven standards have been observed in15 observational runs until May 2014. The calibration results show that the photometric performance of LUT is highly stable in its first six months of operation. The magnitude zero points obtained from the two spectral datasets are also consistent with each other, i.e., zp = 17.54 ± 0.09 mag（set A） and zp = 17.52 ± 0.07 mag（set B）.
基金partly supported by the Bulgarian Ministry of Education and Science under the National Program for Research“Young Scientists and Postdoctoral Students”partial support by grant DN 18-13/2017 from the Bulgarian National Science Fund。
文摘This paper reports results from the first long-term BV(RI)c photometric CCD observations of three variable pre-main-sequence stars collected during the period from February 2007 to January 2020. The investigated stars are located in the field of the PMS star V733 Cep within the Cepheus OB3 association. All stars from our study show rapid photometric variability in all-optical passbands. In this paper, we describe and discuss the photometric behavior of these stars and the possible reasons for their variability. In the light variation of two of the stars, we found periodicity.
基金financial support from the project DST/INT/SA/P-02financial support from the project UGC-BSR research Start-Up Grant Sanctioned vide UGC Order No. F. 30-108/2015(BSR) of UGC
文摘We carry out a re-analysis of the photometric data in Rclc bands which were taken during the Nainital Microlensing Survey from 1998 to 2002 with the aim to detect gravitational microlensing events in the direction of M31. Here, we do photometric analysis of a faint W UMa binary CSS_JO04259.3＋410629 identified in the target field. The orbital period of this star is found to be 0.266402±0.000018 d. The photometric mass ratio, q, is found to be 0.28±0.01. The photometric light curves are investigated using the Wilson-Devinney （WD） code and absolute parameters are determined using empirical relations which provide masses and radii of the binary as M1 = 1.19±0.09M⊙, M2 = 0.33±0.02M⊙ and R1 = 1.02±0.04R⊙, R2 = 0.58±0.08Re respectively based on Rc band data. Quite similar values are found by analyzing/c band data. From the photometric light curve examination, the star is understood to be a low mass-ratio overcontact binary of A-subtype with a high fill-out factor of about 47%. The binary system is found to be located approximately at a distance of 2.64±0.03 kpc having a separation of 2.01 ±0.05 Re between the two components.
基金financial support from the project DST/INT/SA/P-02RJ acknowledges the financial support from the project UGC-BSR research Start-Up Grant Sanctioned vide UGC Order No.F.30-108/2015(BSR)of UGC,under which part of the work has been carried out
文摘We present photometric analysis of the two W UMa type binaries identified in the field of distant open star cluster NGC 6866. Although these systems, namely ID487 and ID494, were reported by Joshi et al., a detailed study of these stars has not been carried out before. The orbital periods of these stars are found to be 0.415110±0.000001 day and 0.366709±0.000004 day, respectively. Based on the photometric and infrared colors, we find their respective spectral types to be K0 and K3. The photometric light vari- ations of both stars show the O＇Connell effect which can be explained by employing a dark spot on the secondary components. The V and I band light curves are analyzed using the Wilson-Devinney （WD） code and relations given by Gazeas which yield radii and masses for the binary components of star ID487 of R1 = 1.24 ± 0.01R,R2 = 1.11 4- 0.02Re, and M1 = 1.24 ± 0.02Me, M2 = 0.96 ±0.05Me and for star ID494 of R1 = 1.22 ± 0.02Re, R2 = 0.81 4- 0.01 Re, and M1 = 1.20 4- 0.06 Me, M2 = 0.47 4- 0.01 Me.
基金supported by the National Natural Science Foundation of China (Grant Nos. 61272272 and U1531122)the Natural Science Foundation of Hubei province (Grant2015CFA058)+1 种基金the National Key Basic Research Program of China (2014CB845700)the NSFC-Texas A&M University Joint Research Program (No.11411120219)
文摘The massive photometric data collected from multiple large-scale sky surveys offer significant opportunities for measuring distances of celestial objects by photometric redshifts. However, catastrophic failure is an unsolved problem with a long history and it still exists in the current photometric redshift estimation approaches （such as the k-nearest neighbor （KNN） algorithm）. In this paper, we propose a novel two-stage approach by integration of KNN and support vector machine （SVM） methods together. In the first stage, we apply the KNN algorithm to photometric data and estimate their corresponding Zphot. Our analysis has found two dense regions with catastrophic failure, one in the range of Zphot E [0.3, 1.2] and the other in the range of Zphot E [1.2, 2.1]. In the second stage, we map the photometric input pattern of points falling into the two ranges from their original attribute space into a high dimensional feature space by using a Gaussian kernel function from an SVM. In the high dimensional feature space, many outliers resulting from catastrophic failure by simple Euclidean distance computation in KNN can be identified by a classification hyperplane of SVM and can be further corrected. Experimental results based on the Sloan Digital Sky Survey （SDSS） quasar data show that the two-stage fusion approach can significantly mitigate catastrophic failure and improve the estimation accuracy of photometric redshifts of quasars. The percents in different /△z/ ranges and root mean square （rms） error by the integrated method are 83.47%, 89.83%, 90.90% and 0.192, respectively, compared to the results by KNN （71.96%, 83.78%, 89.73% and 0.204）.
文摘A new analytical method for detecting butyltin in seawater is presented. In this method, the solid phase microextraction technique for pretreatment of the butyltin compound was used and a new type Flame Photometric Detector (FPD) was designed. Use of this method to determine the butyltin contents in Qingdao coast seawater yielded convincing results.
基金The work is partly supported by the Natural Science Basic Research Plan in Shaanxi Province of China(No.2016JM6041).
文摘There are hundreds of welded studs in a car.The posture of a welded stud determines the quality of the body assembly,thus affecting the safety of cars.It is crucial to detect the posture of the welded studs.Considering the lack of accurate method in detecting the position of welded studs,this paper aims to detect the weld stud’s pose based on photometric stereo and neural network.Firstly,a machine vision-based stud dataset collection system is built to achieve the stud dataset labelling automatically.Secondly,photometric stereo algorithm is applied to estimate the stud normal map which as input is fed to neural network.Finally,we improve a lightweight YOLOv4 neural network which is applied to achieve the detection of stud position,thus overcoming the shortcomings of traditional testing methods.The research and experimental results show that the stud pose detection system designed achieves rapid detection and high accuracy positioning of the stud.This research provides the foundation combining the photometric stereo and deep learning for object detection in industrial production.
基金the anakkale Onsekiz Mart University Research Foundation(Project No.FBA-2018-2452)for supporting this study
文摘Eclipsing binary stars with a pulsating component are powerful tools that allow us to probe the stellar interior structure and the evolutionary statuses with a good accuracy. Therefore, in this study, spectroscopic and photometric examinations of an eclipsing binary system V948 Her are presented. The primary component of the system is classified to be a candidate 3 Scuti variable in the literature. The fundamental stellar, atmospheric and orbital parameters, and the surface abundance of the star were determined and the pulsation behaviour was investigated in this study. The orbital parameters were derived by the analysis of radial velocity and SuperWASP light curves. The spectral classification was found to be F2V. The initial atmospheric parameters of the primary component were derived by analysis of the spectral energy distribution and hydrogen lines. The final atmospheric parameters and chemical abundances of the primary component were obtained by using the method of spectrum synthesis. As a result, the final atmospheric parameters were determined as Teff= 7100±200 K, log 9= 4.34±0.1 cgs and ζ = 2.2 4± 0.2 km s^-1. The surface abundance was found to be similar to solar. The fundamental stellar parameters of both components were also obtained to be M = 1.722 4±0.123, 0.762 4± 0.020 Me, R = 1.655 4± 0.034,M,R= 0.689 ± 0.016 R for primary and secondary components, respectively. The pulsation characteristic of the primary component was examined using SuperWASP data and the pulsation period was found to be ~0.038 d. The position of the primary pulsating component was also obtained inside the instability strip of δ Sct stars. The primary component of V948 Her was defined to be a Sct variable.
基金funded by the National Natural Science Foundation of China(Grant Nos.11073051 and 11473066)by the Open Project of Key Laboratory of Space Object and Debris Observation,Chinese Academy of Sciences(Title:Photometric study of space debris in near geostationary orbit)
文摘We characterize the morphology of the photometric phase curve model of an asteroid with a three- parameter magnitude phase function H - G1 - G2 system by considering the effect of brightness variation arising from a triaxial ellipsoid representing the asteroid＇s shape. Applying this new model and a Markov Chain Monte Carlo method, we refine the photometric phase curve of asteroid （107） Camilla and obtain its absolute magnitude H = 7.026-0.054^＋0.052 mag, and phase function parameters G1=0.489-0.044^＋0.043 and G2 = 0.259-0.023^＋0.023.Meanwhile, we also determine （107） Camilla＇s orientation of pole （74.1°-4.5°^＋4.3°,50.2°-5.0°^＋5.4°）. with rotational period of 4.843928-0.000001^＋0.000001 h, and axial ratios a/b ： 1.409-0.020^＋0.020 And b/c =1.249-0.060^＋0.063. Furthermore, according to the values of phase function parameters G1 and G2, we infer that asteroid （107） Camilla is an X-type asteroid.
基金Sponsored by the China Postdoctoral Science Foundation (Grant No. 2003033332)Scientific Research Foundation of Harbin Institute of Technology (Grant No. HIT2002.24)
文摘The main role of water treatment plants is to supply high-quality safe drinking water. Coagulation is one of the most important stages of surface water treatment. The photometric dispersion analyzer(PDA) is a new optical method for flocculation monitoring, and is feasible to realize coagulation feedback control. The on line modification of the coagulation control system' s set point( or optimum dosing coagulant) has influenced the application of this technology in water treatment plant for a long time. A fuzzy control system incorporating the photometric dispersion analyzer was utilized in this coagulation control system. Proposed is a fuzzy logic inference control system by using Takagi and Sugeno' s fuzzy if-then rule for the self-correction of set point on line. Programmed is the dosing rate fuzzy control system in SIEMENS small-scale programmable logic controller. A 400 L/min middle-scale water treatment plant was utilized to simulate the reaction. With the changes of raw water quality, the set point was modified correctly in time, as well as coagulant dosing rate, and residual turbility before filtration was eligible and stable. Results show that this fuzzy inference and control system performs well on the coagulation control system through PDA.
基金financial support from the UNAM under DGAPA grant PAPIIT IN100918。
文摘We present the results of our study of the eclipsing binary systems CSS J112237.1+395219,LINEAR 1286561 and LINEAR 2602707 based on new CCD B,V,Rcand Iccomplete light curves.The ultra-short period nature of these stars,as reported by Drake et al.,is confirmed and the system’s periods are revised.The light curves were modeled using the 2003 version of the Wilson-Devinney code.When necessary,cool spots on the surface of the primary component were introduced to account for asymmetries in the light curves.As a result,we found that CSS J112237.1+395219 is a W UMa type contact binary system belonging to W subclass with a mass ratio of q=1.61 and a shallow degree of contact of 14.8%where the primary component is hotter than the secondary one by 500 K.LINEAR 1286561 and LINEAR2602707 are detached binary systems with mass ratios q=3.467 and q=0.987 respectively.These detached systems are low-mass M-type eclipsing binaries with similar temperatures.The marginal contact,fill-out factor and temperature difference between components of CSS J112237.1+395219 suggest that this system may be at a key evolutionary state predicted by thermal relaxation oscillation(TRO)theory.From the estimated absolute parameters,we conclude that our systems share common properties with other ultrashort period binaries.
