In this study,the apsidal motion analyses of the eclipsing binary systems V398 Lac,V2544 Cyg,and V785 Cas are presented.The(O-C)diagrams of the selected systems were constructed using all available and reliable times ...In this study,the apsidal motion analyses of the eclipsing binary systems V398 Lac,V2544 Cyg,and V785 Cas are presented.The(O-C)diagrams of the selected systems were constructed using all available and reliable times of minimum light compiled from the literature.As a result,the apsidal motion periods were determined to be 353±50 yr,43.3±5.1 yr and 83.4±8.5 yr,respectively.Furthermore,the TESS light curves of the three systems were analyzed to derive their photometric and absolute parameters.The component masses were determined as follows:for V398 Lac,M_(1)=3.83±0.35 M_(⊙)and M2=3.27±0.35 M_(⊙);for V2544 Cyg,M_(1)=1.75±0.38 M_(⊙)and M2=1.40±0.38 M_(⊙);for V785 Cas,M_(1)=5.64±0.41 M_(⊙)and M2=5.18±0.41 M_(⊙).The parameters related to apsidal motion,as well as the observational and theoretical internal structure constants(K_(2,obs) and K_(2,teo))were calculated for studied binaries.The relativistic contribution to the observed apsidal motion rate was found to be relatively small,constituting less than approximately 5%of the total rate in each system.The theoretical internal structure constants were derived from the evolutionary models,assuming a standard chemical composition of(X,Z)=(0.70,0.01).展开更多
We present the results of our study of the long-period eclipsing binary star V454 Aur.The results are based on spectroscopic data obtained with the UFESéchelle spectrograph and photometric observations from Trans...We present the results of our study of the long-period eclipsing binary star V454 Aur.The results are based on spectroscopic data obtained with the UFESéchelle spectrograph and photometric observations from Transiting Exoplanet Survey Satellite(TESS).The derived radial velocity curve is based on 17 spectra obtained between 2021and 2023,covering all orbital phases of this binary system.The orbital period determined from TESS data,P=27.019803±0.000003 days,agrees within uncertainties with the period established in previous studies.The model constructed for the TESS photometric light curve achieves a precision of 0.01%.The effective temperatures of both components,as well as the system metallicity,were directly derived from the spectra and are Teff,A=6250±50 K,Teff,B=5855±50 K,and[Fe/H]=-0.10±0.08,respectively.Our analysis of the photometric and spectroscopic data allowed us to directly compute the luminosities of the components,LA=1.82 L☉and LB=1.07 L☉,their radii,RA=1.15 R☉and RB=1.00 R☉,and their masses,MA=1.137 M☉and MB=1.023 M☉,with uncertainties below 1%.Comparison with evolutionary tracks indicates that the system’s age is 1.18±0.10 Gyr,and both components are still on the main sequence.The V454 Aur system is particularly interesting due to the partial eclipse of the primary component,which results in the“inversion”of the primary and secondary minima in the photometric light curve.展开更多
We report results of our optical photometric observations of ten gamma-ray loud blazers, namely: 0219+428 (3C66A), PKS 0420-014 (OA 129), S5 0716+714, 0754+100 (OI 090.4), 0827+243 (OJ248), 1652+398 (Mrk 501), 2200+42...We report results of our optical photometric observations of ten gamma-ray loud blazers, namely: 0219+428 (3C66A), PKS 0420-014 (OA 129), S5 0716+714, 0754+100 (OI 090.4), 0827+243 (OJ248), 1652+398 (Mrk 501), 2200+420 (BL Lacertae), 2230+114 (CTA 102), 2251+158 (3C 454.3) and 2344+514. The observations were carried out in September-October, 2000 using the 70 cm optical telescope at Abstumani Observatory, Georgia. We found intra-day variations in 0420-014, S5 0716+714, BL Lacertae and CTA 102. A variation of 0.3 magnitude over a time scale of about 3 hours was observed in the R passband in BL Lacertae on JD 2451827. We did not detect any variation in 3C 66A, Mrk 501, or 3C 454.3 during our observations. Nor did we detect any clear evidence of variation in 1ES 2344+514 during our two weeks' observing run of the TeV gamma-ray source.展开更多
We present photometric observations in Sloan filters g′, i′of the eclipsing W UMa stars USNOA2.0 1350-17365531, V471 Cas, V479 Lac and V560 Lac. The sinusoidal-like O-C diagram of V471 Cas indicates the presence of ...We present photometric observations in Sloan filters g′, i′of the eclipsing W UMa stars USNOA2.0 1350-17365531, V471 Cas, V479 Lac and V560 Lac. The sinusoidal-like O-C diagram of V471 Cas indicates the presence of a third body with mass 0.12 M_⊙(a red dwarf) at distance 897 R_⊙. The O-C diagram of V479 Lac reveals a period decrease of d P/dt =-1.69 × 10-6d yr-1. The results of the light curve solutions are:(i) the targets are overcontact binaries with small fill-out factors;(ii) their components are F–K stars, comparable in size, whose temperature differences are below 80 K;(iii) all targets undergo partial eclipses and to limit the possible mass ratios we carried out two-step q-search analysis. The target global parameters(luminosities, radii, masses) were obtained on the basis of their Gaia distances and the results of our light curve solutions. The obtained total mass of V560 Lac turns out to be smaller than the lower mass limit for presently known W UMa binaries of 1.0-1.2 M_⊙, i.e. this target is a peculiar overcontact system.展开更多
High-precision CCD photometric observations of the contact binary V680 Per were obtained in2016.Its symmetric multi-color light curves were analyzed by using the Wilson–Devinney(2013)program.These photometric solutio...High-precision CCD photometric observations of the contact binary V680 Per were obtained in2016.Its symmetric multi-color light curves were analyzed by using the Wilson–Devinney(2013)program.These photometric solutions suggest that V680 Per is an A-type W UMa contact binary with the mass ratio of q=0.693 and a fill-out factor of f=18.84%with a small temperature difference of 101 K.Based on all minimum times,the O-C curve was analyzed for the first time in this study.A cyclic oscillation(A3=0.00093 d,T3=4.92 yr)superimposed on a secular decrease(d P/dt=-8.16×10-8 d yr-1)was identified.The continuous decrease in period is possibly a result of mass transfer from the more massive component to the less massive one,or angular momentum loss due to a magnetic stellar wind.Because of this secular decrease,it is predicted that the degree of contact will become higher,and V680 Per will evolve into a deeper overcontact binary.展开更多
New light curves and photometric solutions of FP Lyn,FV CVn and V354 UMa are presented.We found that these three systems are W-subtype shallow contact binaries.In addition,it is obvious that the light curves of FP Lyn...New light curves and photometric solutions of FP Lyn,FV CVn and V354 UMa are presented.We found that these three systems are W-subtype shallow contact binaries.In addition,it is obvious that the light curves of FP Lyn and V354 UMa are asymmetric.Therefore,a hot spot was added on the primary star of FP Lyn and a dark spot was added on the secondary star of V354 UMa.At the same time,we added a third light to the photometric solution of FP Lyn for the final result.The obtained mass ratios and fill-out factors are q = 1.153 and f = 13.4% for FP Lyn,q = 1.075 and f = 4.6% for FV CVn,and q = 3.623 and f = 10.7% for V354 UMa respectively.The investigations of orbital period for these three systems indicate that the periods are variable.FP Lyn and V354 UMa were discovered to have secularly increasing components with rates of dp/dt = 4.19 ×10^-7 dyr^-1 and dp/dt = 7.70 ×10^-7 dyr^-1 respectively,which are feasibly caused by conservative mass transfer from the less massive component to the more massive component.In addition,some variable components were discovered for FV CVn,including a rate of dp/dt =-1.13 ×10^-6 dyr^-1 accompanied by a cyclic oscillation with amplitude and period of 0.0069 d and 10.65 yr respectively.The most likely explanation for the long-term decrease is angular momentum loss.The existence of an additional star is the most plausible explanation for the periodic variation.展开更多
Nova Sco 2008(=V1309 Sco)is an example of a V838 Mon type eruption rather than a typical classical nova.This enigmatic object was recently shown to have resulted from the merger of two stars in a contact binary.It is ...Nova Sco 2008(=V1309 Sco)is an example of a V838 Mon type eruption rather than a typical classical nova.This enigmatic object was recently shown to have resulted from the merger of two stars in a contact binary.It is the first stellar merger that was identified to be undergoing a common envelope transient.To understand the properties of its binary progenitor,the pre-outburst light curves were analyzed by using the W-D method.The photometric solution of the 2002 light curve shows that it is a deep contact binary(f=89.5(~40.5)%)with a mass ratio of 0.094.The asymmetry of the light curve is explained by the presence of a dark spot on the more massive component.The extremely high fill-out factor suggests that the merging of the contact binary is driven by dynamical mass loss from the outer Lagrange point.However,the analysis of the 2004 light curve indicates that no solutions were obtained even at an extremely low mass ratio of q=0.03.This suggests that the common convective envelope of the binary system disappeared and the secondary component spiraled into the envelope of the primary in 2004.Finally,the ejection of the envelope of the primary produced the outburst.展开更多
New multi-color BVRcIc photometric observations are presented for the W UMa type eclips- ing binary V1073 Cyg. The multi-color light curve analysis with the Wilson-Devinney procedure yielded the absolute parameters of...New multi-color BVRcIc photometric observations are presented for the W UMa type eclips- ing binary V1073 Cyg. The multi-color light curve analysis with the Wilson-Devinney procedure yielded the absolute parameters of this system, showing that V 1073 Cyg is a shallow contact binary system with a fill-out factor f = 0.124（±0.011）. We collected all available times of light minima spanning 119yr, including CCD data to construct the O - C curve, and performed detailed O - C analysis. The O - C diagram shows that the period change is complex. A long-term continuous decrease and a cyclic vari- ation exist. The period is decreasing at a rate ofP = -1.04（±0.18） × 10-10 d cycle-land, with the period decrease, V1073 Cyg will evolve to the deep contact stage. The cyclic variation with a period of P3 = 82.7（±3.6） yr and an amplitude of A = 0.028（±0.002） d may be explained by magnetic activ- ity of one or both components or the light travel time effect caused by a distant third companion with M3（i1 = 90°） = 0.511 M⊙.展开更多
By analyzing two sets of complete BV Rc Ic light curves for V342 UMa and three sets of complete BV Rc Ic light curves for V509 Cam, we determined that the two systems are both W-subtype contact binaries and that V342 ...By analyzing two sets of complete BV Rc Ic light curves for V342 UMa and three sets of complete BV Rc Ic light curves for V509 Cam, we determined that the two systems are both W-subtype contact binaries and that V342 UMa manifests a shallow contact configuration, while V509 Cam exhibits a medium contact configuration. Given that both of them are totally eclipsing binaries, the physical parameters derived only by the photometric light curves are reliable. Meanwhile, the period changes of the two targets were analyzed based on all available eclipsing times. We discovered that V342 UMa shows long-term period decrease with a rate of-1.02(±0.54)× 10^-7 d yr^-1 and that V509 Cam displays long-term period increase with a rate of 3.96(±0.90)× 10^-8 d yr^-1. Both the conservative mass transfer and angular momentum loss via magnetic stellar winds can be used to interpret the long-term period decrease of V342 UMa. The longterm period increase of V509 Cam can be explained by mass transfer from the less massive star to the more massive one. The absolute parameters of the two binaries were estimated according to their Gaia distances and our derived photometric solution results. This method can be extended to other contact binaries without radial velocities but with reliable photometric solutions. Their evolutionary states were investigated and we found that they reveal properties that are identical to other W-subtype contact systems.展开更多
A photometric analysis and evolutionary stages of the contact binary V2790 Ori are presented.The BV RC observations were carried out at the Thai National Observatory. The photometric light curves were fitted to provid...A photometric analysis and evolutionary stages of the contact binary V2790 Ori are presented.The BV RC observations were carried out at the Thai National Observatory. The photometric light curves were fitted to provide fundamental parameters, required to examine evolutionary stages of the binary. The results indicate that V2790 Ori is a W-type contact system with a mass ratio of q = 2.932. The orbital period increase is found at a rate of d P/dt = 1.03×10^-7 d yr^-1. This implies that a rate of mass transfer from the secondary component to the primary one is dm2/dt =6.31×10^-8 M⊙yr^-1. Furthermore, we find that from the detached phase to the contact phase, the amount of mass that the evolved secondary component has lost is 1.188±0.110 M⊙, i.e., mass lost by the system is 0.789±0.073 M⊙and mass transfer to the primary is0.399±0.037 M⊙. Since the time of the first overflow, the angular momentum loss is found to be 72.2% of JFOF, causing the orbit and Roche surface to shrink until the present time.展开更多
AIM: To study the effect of NS-398, a selective cydooxygenase 2 (COX-2) inhibitor, on invasion of colon cancer cell line HT-29 in vitro and to explore its mechanisms. METHODS: Invasive behaviors of the malignant colon...AIM: To study the effect of NS-398, a selective cydooxygenase 2 (COX-2) inhibitor, on invasion of colon cancer cell line HT-29 in vitro and to explore its mechanisms. METHODS: Invasive behaviors of the malignant colon cancer cell line HT-29 were investigated in this study. Expressions of COX-2 and CD44v6 in HT-29 cells were detected by flow cytometry. Cellular survival rate was determined by MTT assay. The invasive capacity was quantified by a modified Boyden chamber model. Alterations of cytoskeleton component F-actin were observed by confocal laser scanning microscope. RESULTS: Flow cytometry analysis showed that COX-2 was highly expressed in HT-29 cells. The invasive capability of HT-29 cells could be greatly inhibited by NS-398 at the experimental concentrations of 0.1,1.0 and 10 μmol/L with an inhibitory rate of 22.74%, 42.35% and 58.61% (P<0.01), respectively. MTT assay showed that NS-398 at the experimental concentrations had no significant influence on cellular viability, indicating that such anti-invasive effects had no relationship with cytotoxicity. F-actin was mainly distributed around nuclei forming annular structure in HT-29 cells. After exposure to NS-398 of 10 μmol/L, the annular structure around nuclei disappeared and the fluorescence intensity of F-actin decreased obviously. Treatment with NS-398 could down-regulate the expression of CD44v6 as well. CONCLUSION: NS-398 has anti-invasive effects on colon cancer HT-29 cells in vitro, which may be mediated by a novel mechanism of disruption of cytoskeleton. Down-regulation of CD44v6 expression may be related to alterations of cytoskeleton.展开更多
基金Funding for TESS is provided by the NASA Science Mission Directorate。
文摘In this study,the apsidal motion analyses of the eclipsing binary systems V398 Lac,V2544 Cyg,and V785 Cas are presented.The(O-C)diagrams of the selected systems were constructed using all available and reliable times of minimum light compiled from the literature.As a result,the apsidal motion periods were determined to be 353±50 yr,43.3±5.1 yr and 83.4±8.5 yr,respectively.Furthermore,the TESS light curves of the three systems were analyzed to derive their photometric and absolute parameters.The component masses were determined as follows:for V398 Lac,M_(1)=3.83±0.35 M_(⊙)and M2=3.27±0.35 M_(⊙);for V2544 Cyg,M_(1)=1.75±0.38 M_(⊙)and M2=1.40±0.38 M_(⊙);for V785 Cas,M_(1)=5.64±0.41 M_(⊙)and M2=5.18±0.41 M_(⊙).The parameters related to apsidal motion,as well as the observational and theoretical internal structure constants(K_(2,obs) and K_(2,teo))were calculated for studied binaries.The relativistic contribution to the observed apsidal motion rate was found to be relatively small,constituting less than approximately 5%of the total rate in each system.The theoretical internal structure constants were derived from the evolutionary models,assuming a standard chemical composition of(X,Z)=(0.70,0.01).
基金support from the National Research Foundation(NRF)of South Africasupported by the Ministry of Science and Higher Education of Russia,topic No.FEUZ-2023-0019。
文摘We present the results of our study of the long-period eclipsing binary star V454 Aur.The results are based on spectroscopic data obtained with the UFESéchelle spectrograph and photometric observations from Transiting Exoplanet Survey Satellite(TESS).The derived radial velocity curve is based on 17 spectra obtained between 2021and 2023,covering all orbital phases of this binary system.The orbital period determined from TESS data,P=27.019803±0.000003 days,agrees within uncertainties with the period established in previous studies.The model constructed for the TESS photometric light curve achieves a precision of 0.01%.The effective temperatures of both components,as well as the system metallicity,were directly derived from the spectra and are Teff,A=6250±50 K,Teff,B=5855±50 K,and[Fe/H]=-0.10±0.08,respectively.Our analysis of the photometric and spectroscopic data allowed us to directly compute the luminosities of the components,LA=1.82 L☉and LB=1.07 L☉,their radii,RA=1.15 R☉and RB=1.00 R☉,and their masses,MA=1.137 M☉and MB=1.023 M☉,with uncertainties below 1%.Comparison with evolutionary tracks indicates that the system’s age is 1.18±0.10 Gyr,and both components are still on the main sequence.The V454 Aur system is particularly interesting due to the partial eclipse of the primary component,which results in the“inversion”of the primary and secondary minima in the photometric light curve.
基金Supported by the National Natural Science Foundation of China
文摘We report results of our optical photometric observations of ten gamma-ray loud blazers, namely: 0219+428 (3C66A), PKS 0420-014 (OA 129), S5 0716+714, 0754+100 (OI 090.4), 0827+243 (OJ248), 1652+398 (Mrk 501), 2200+420 (BL Lacertae), 2230+114 (CTA 102), 2251+158 (3C 454.3) and 2344+514. The observations were carried out in September-October, 2000 using the 70 cm optical telescope at Abstumani Observatory, Georgia. We found intra-day variations in 0420-014, S5 0716+714, BL Lacertae and CTA 102. A variation of 0.3 magnitude over a time scale of about 3 hours was observed in the R passband in BL Lacertae on JD 2451827. We did not detect any variation in 3C 66A, Mrk 501, or 3C 454.3 during our observations. Nor did we detect any clear evidence of variation in 1ES 2344+514 during our two weeks' observing run of the TeV gamma-ray source.
基金supported partly by project DN08/20 of the Scientific Foundation of the Bulgarian Ministry of Education and Scienceby project RD 08-142 of Shumen University+1 种基金the support of the private IRIDA Observatory operated remotely(www.iridaobservatory.org)Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement
文摘We present photometric observations in Sloan filters g′, i′of the eclipsing W UMa stars USNOA2.0 1350-17365531, V471 Cas, V479 Lac and V560 Lac. The sinusoidal-like O-C diagram of V471 Cas indicates the presence of a third body with mass 0.12 M_⊙(a red dwarf) at distance 897 R_⊙. The O-C diagram of V479 Lac reveals a period decrease of d P/dt =-1.69 × 10-6d yr-1. The results of the light curve solutions are:(i) the targets are overcontact binaries with small fill-out factors;(ii) their components are F–K stars, comparable in size, whose temperature differences are below 80 K;(iii) all targets undergo partial eclipses and to limit the possible mass ratios we carried out two-step q-search analysis. The target global parameters(luminosities, radii, masses) were obtained on the basis of their Gaia distances and the results of our light curve solutions. The obtained total mass of V560 Lac turns out to be smaller than the lower mass limit for presently known W UMa binaries of 1.0-1.2 M_⊙, i.e. this target is a peculiar overcontact system.
基金supported by the Joint Research Found(Nos.U1831109 and U1631108)in Astronomy under cooperative agreement between the National Natural Science Foundation of China(NSFC)and Chinese Academy of Sciences(CAS)the Science Foundation of China University of Petroleum-Beijing at Karamay(Nos.RCYJ 2016B-03-004 and 2016B-03-006)Key Laboratory for the Structure and Evolution ofCelestial Objects,Chinese Academy of Sciences(No.OP201708)。
文摘High-precision CCD photometric observations of the contact binary V680 Per were obtained in2016.Its symmetric multi-color light curves were analyzed by using the Wilson–Devinney(2013)program.These photometric solutions suggest that V680 Per is an A-type W UMa contact binary with the mass ratio of q=0.693 and a fill-out factor of f=18.84%with a small temperature difference of 101 K.Based on all minimum times,the O-C curve was analyzed for the first time in this study.A cyclic oscillation(A3=0.00093 d,T3=4.92 yr)superimposed on a secular decrease(d P/dt=-8.16×10-8 d yr-1)was identified.The continuous decrease in period is possibly a result of mass transfer from the more massive component to the less massive one,or angular momentum loss due to a magnetic stellar wind.Because of this secular decrease,it is predicted that the degree of contact will become higher,and V680 Per will evolve into a deeper overcontact binary.
基金financial support from the Universidad Nacional Aut ónoma de México (UNAM) and DGAPA (PAPIIT IN 100918)supported by the National Natural Science Foundation of China (NSFC) (No. 11703016)+3 种基金by the Joint Research Fund in Astronomy (No. U1431105)by the Natural Science Foundation of Shandong Province (No. ZR2014AQ019)by the Young Scholars Program of Shandong University, Weihai (No. 20820171006)by the Open Research Program of Key Laboratory for the Structure and Evolution of Celestial Objects (No. OP201704)
文摘New light curves and photometric solutions of FP Lyn,FV CVn and V354 UMa are presented.We found that these three systems are W-subtype shallow contact binaries.In addition,it is obvious that the light curves of FP Lyn and V354 UMa are asymmetric.Therefore,a hot spot was added on the primary star of FP Lyn and a dark spot was added on the secondary star of V354 UMa.At the same time,we added a third light to the photometric solution of FP Lyn for the final result.The obtained mass ratios and fill-out factors are q = 1.153 and f = 13.4% for FP Lyn,q = 1.075 and f = 4.6% for FV CVn,and q = 3.623 and f = 10.7% for V354 UMa respectively.The investigations of orbital period for these three systems indicate that the periods are variable.FP Lyn and V354 UMa were discovered to have secularly increasing components with rates of dp/dt = 4.19 ×10^-7 dyr^-1 and dp/dt = 7.70 ×10^-7 dyr^-1 respectively,which are feasibly caused by conservative mass transfer from the less massive component to the more massive component.In addition,some variable components were discovered for FV CVn,including a rate of dp/dt =-1.13 ×10^-6 dyr^-1 accompanied by a cyclic oscillation with amplitude and period of 0.0069 d and 10.65 yr respectively.The most likely explanation for the long-term decrease is angular momentum loss.The existence of an additional star is the most plausible explanation for the periodic variation.
基金supported by the National Natural Science Foundation of China(Nos.11133007,11325315 and 11573063)the Key Research Program of the Chinese Academy of Sciences(Grant No.KGZD-EW-603)+1 种基金the Science Foundation of Yunnan Province(Nos.2012HC011 and 2013FB084)the Strategic Priority Research Program“The Emergence of Cosmological Structures”of the Chinese Academy of Sciences(No.XDB09010202)
文摘Nova Sco 2008(=V1309 Sco)is an example of a V838 Mon type eruption rather than a typical classical nova.This enigmatic object was recently shown to have resulted from the merger of two stars in a contact binary.It is the first stellar merger that was identified to be undergoing a common envelope transient.To understand the properties of its binary progenitor,the pre-outburst light curves were analyzed by using the W-D method.The photometric solution of the 2002 light curve shows that it is a deep contact binary(f=89.5(~40.5)%)with a mass ratio of 0.094.The asymmetry of the light curve is explained by the presence of a dark spot on the more massive component.The extremely high fill-out factor suggests that the merging of the contact binary is driven by dynamical mass loss from the outer Lagrange point.However,the analysis of the 2004 light curve indicates that no solutions were obtained even at an extremely low mass ratio of q=0.03.This suggests that the common convective envelope of the binary system disappeared and the secondary component spiraled into the envelope of the primary in 2004.Finally,the ejection of the envelope of the primary produced the outburst.
基金partly supported by the National Natural Science Foundation of China(Nos.11573063,11325315 and U1631108)the Key Science Foundation of Yunnan Province(No.2017FA001)+1 种基金Chinese Academy of Sciences“Light of West China”Programthe research fund of Sichuan University of Science and Engineering(Grant No.2015RC42)
文摘New multi-color BVRcIc photometric observations are presented for the W UMa type eclips- ing binary V1073 Cyg. The multi-color light curve analysis with the Wilson-Devinney procedure yielded the absolute parameters of this system, showing that V 1073 Cyg is a shallow contact binary system with a fill-out factor f = 0.124（±0.011）. We collected all available times of light minima spanning 119yr, including CCD data to construct the O - C curve, and performed detailed O - C analysis. The O - C diagram shows that the period change is complex. A long-term continuous decrease and a cyclic vari- ation exist. The period is decreasing at a rate ofP = -1.04（±0.18） × 10-10 d cycle-land, with the period decrease, V1073 Cyg will evolve to the deep contact stage. The cyclic variation with a period of P3 = 82.7（±3.6） yr and an amplitude of A = 0.028（±0.002） d may be explained by magnetic activ- ity of one or both components or the light travel time effect caused by a distant third companion with M3（i1 = 90°） = 0.511 M⊙.
基金supported by the National Natural Science Foundation of China (No. 11703016)the Joint Research Fund in Astronomy (No. U1431105) under cooperative agreement between the National Natural Science Foundation of China and the Chinese Academy of Sciences+5 种基金the program of the Light in China’s Western Region (No. 2015-XBQNA-02)the Natural Science Foundation of Shandong Province (Nos. ZR2014AQ019 and JQ201702)the Young Scholars Program of Shandong University, Weihai (Nos. 20820162003 and 20820171006)the program of Tianshan Youth (No. 2017Q091)the Open Research Program of Key Laboratory for the Structure and Evolution of Celestial Objects (No. OP201704)partially supported by the Open Project Program of the Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences
文摘By analyzing two sets of complete BV Rc Ic light curves for V342 UMa and three sets of complete BV Rc Ic light curves for V509 Cam, we determined that the two systems are both W-subtype contact binaries and that V342 UMa manifests a shallow contact configuration, while V509 Cam exhibits a medium contact configuration. Given that both of them are totally eclipsing binaries, the physical parameters derived only by the photometric light curves are reliable. Meanwhile, the period changes of the two targets were analyzed based on all available eclipsing times. We discovered that V342 UMa shows long-term period decrease with a rate of-1.02(±0.54)× 10^-7 d yr^-1 and that V509 Cam displays long-term period increase with a rate of 3.96(±0.90)× 10^-8 d yr^-1. Both the conservative mass transfer and angular momentum loss via magnetic stellar winds can be used to interpret the long-term period decrease of V342 UMa. The longterm period increase of V509 Cam can be explained by mass transfer from the less massive star to the more massive one. The absolute parameters of the two binaries were estimated according to their Gaia distances and our derived photometric solution results. This method can be extended to other contact binaries without radial velocities but with reliable photometric solutions. Their evolutionary states were investigated and we found that they reveal properties that are identical to other W-subtype contact systems.
文摘A photometric analysis and evolutionary stages of the contact binary V2790 Ori are presented.The BV RC observations were carried out at the Thai National Observatory. The photometric light curves were fitted to provide fundamental parameters, required to examine evolutionary stages of the binary. The results indicate that V2790 Ori is a W-type contact system with a mass ratio of q = 2.932. The orbital period increase is found at a rate of d P/dt = 1.03×10^-7 d yr^-1. This implies that a rate of mass transfer from the secondary component to the primary one is dm2/dt =6.31×10^-8 M⊙yr^-1. Furthermore, we find that from the detached phase to the contact phase, the amount of mass that the evolved secondary component has lost is 1.188±0.110 M⊙, i.e., mass lost by the system is 0.789±0.073 M⊙and mass transfer to the primary is0.399±0.037 M⊙. Since the time of the first overflow, the angular momentum loss is found to be 72.2% of JFOF, causing the orbit and Roche surface to shrink until the present time.
文摘AIM: To study the effect of NS-398, a selective cydooxygenase 2 (COX-2) inhibitor, on invasion of colon cancer cell line HT-29 in vitro and to explore its mechanisms. METHODS: Invasive behaviors of the malignant colon cancer cell line HT-29 were investigated in this study. Expressions of COX-2 and CD44v6 in HT-29 cells were detected by flow cytometry. Cellular survival rate was determined by MTT assay. The invasive capacity was quantified by a modified Boyden chamber model. Alterations of cytoskeleton component F-actin were observed by confocal laser scanning microscope. RESULTS: Flow cytometry analysis showed that COX-2 was highly expressed in HT-29 cells. The invasive capability of HT-29 cells could be greatly inhibited by NS-398 at the experimental concentrations of 0.1,1.0 and 10 μmol/L with an inhibitory rate of 22.74%, 42.35% and 58.61% (P<0.01), respectively. MTT assay showed that NS-398 at the experimental concentrations had no significant influence on cellular viability, indicating that such anti-invasive effects had no relationship with cytotoxicity. F-actin was mainly distributed around nuclei forming annular structure in HT-29 cells. After exposure to NS-398 of 10 μmol/L, the annular structure around nuclei disappeared and the fluorescence intensity of F-actin decreased obviously. Treatment with NS-398 could down-regulate the expression of CD44v6 as well. CONCLUSION: NS-398 has anti-invasive effects on colon cancer HT-29 cells in vitro, which may be mediated by a novel mechanism of disruption of cytoskeleton. Down-regulation of CD44v6 expression may be related to alterations of cytoskeleton.
