A new ephemeris, period change analysis and light curve modeling of the W UMa-type eclipsing binary BF Pav are presented in this study. Light curves of the system taken in BVRI filters from two observatories in Australia and Argentina were modeled using the Wilson-Devinney code. The results of this analysis demonstrate that BF Pav is a contact binary system with a photometric mass ratio q=1.460+_0.014, a fillout factor f=12.5%, an inclination of 87.97+_0.45 deg and a cold spot on the secondary component. By using the distance modulus formula, the distance of BF Pav was calculated to be d=268+_18 pc which is in good agreement with the Gaia EDR3 distance. We obtain an orbital period increase at a rate of 0.142 s/century due to a quadratic trend in the O-C diagram. Also, an alternative sudden period jump probably has occurred which could be interpreted as a rapid mass transfer from the lower mass star to its companion about DeltaM=2.45*10^(-6) Msun. Furthermore, there is an oscillatory behavior with a period of 18.3+_0.3 yr. Since BF Pav does not seem to have significant magnetic activity, this behavior could be interpreted as the light-time effect caused by an undetected third body in this system. In this case, the probability for the third body to be a low mass star with M>=0.075 Msun or a brown dwarf is 5.4% and 94.6% respectively. If we assume i'=90deg, a_3=8.04+_0.33 AU. The mass of the secondary component was also determined using two different methods which result close to each other.
This paper reports the results from the multicolor photometric observations of 15 pre-main sequence stars collected in the period 2010 September - 2017 October. The stars from our study are located in the star-forming HII region IC 5070. These objects were previously detected as either emission line stars, flare stars, T Tauri variables or Herbig Ae/Be stars. Photometric observations, especially concerning the long-term behavior of the objects are missing in the literature. We present the first photometric monitoring for all stars from our study. The analysis of the obtained BVRI photometric d…
The Asiago plate archive has been searched for old plates covering the region of the sky containing Nova Del 2013 (V339 Del). The brightness of the progenitor was measured against a deep BVRI photometric sequence that we calibrated on purpose. The mean brightness of the progenitor on Asiago plates is <B>=17.27 and <V>=17.6, for a mean color (B-V) = -0.33. The recorded total amplitude of variation in B band is 0.9 mag. Color and variability are in agreement with a progenitor dominated by the emission from an accretion disc. The progenitor was marginally detected also by the APASS all sky survey…
We present new data from BVRI photometric observations of five PMS stars during the period from April 2013 to July 2014. The stars are located in the field of NGC 7000/IC 5070 ("Gulf of Mexico") - a region with active star formation. The presented paper is a continuation of our long-term photometric investigations of the young stellar objects in this region. The long-term multicolor photometric observations of PMS stars are very important for their exact classification. Our results show that the studied stars exhibit different types of photometric variability in all bands. We tried to classify…
The very fast, FeII-class Nova Ophiuchi 2010 N.1 rised rapidly to maximum brightness (the last 2.2 mag in V band were covered in 3.4 days), maximum that was reached on Jan. 18.3, 2010 at V=8.5, B-V=+0.95, V-Rc=+0.75, and V-Ic=+1.50. The rapid and smooth decline was charaterized by t2(V)=10.0 and t3(V)=23.5 days. The reddening affecting the nova was E(B-V)=0.7 and its distance d=7.4 kpc, for an height above the galactic plane of z=0.6 kpc.
We have done photometric calibration of the 60 cm Nedeljković telescope equipped with FLI PL 230 CCD camera, mounted at the Astronomical Station Vidojevica (Serbia), using standard stars from the Landolt's catalog. We have imaged 31 fields of standard stars using Johnson's $BVRI$ filters during three nights in August 2019. We have measured both extinction and color correction. Relating our calibrated magnitudes to the magnitudes of the standard stars from the Landolt's catalog, we have achieved accuracy of 2\%-5\% for the $BVRI$ magnitudes.
CCD photometric observations of the Algol-type eclipsing binary X Tri have been obtained. The light curves are analyzed with the Wilson-Devinney (WD) code and new geometric and photometric elements are derived. A new O-C analysis of the system, based on the most reliable timings of minima found in the literature, is presented and apparent period changes are discussed with respect to possible and multiple Light-Time Effect (LITE) in the system. Moreover, the results for the existence of additional bodies around the eclipsing pair, derived from the period study, are compared with those for extra…
We present analysis of optical photometric and polarimetric observations of contact binary system FO Hydra (FO Hya). The computed period of the system is 0.469556+/-0.000003 days. An O-C curve analysis indicates an increase in its period by 5.77x10^{-8} day yr^{-1}. The photometric light curves are analyzed using Wilson-Devinney code (WD). The present analysis shows that FO Hya is a B-subtype of W UMa type contact binary. The radii and mass of primary and secondary components are found, respectively, to be R_1 = 1.62+/-0.03 R_sun and R_2 = 0.91+/-0.02 R_sun, and M_1 = 1.31+/-0.07 M_sun and M_2…
New BVRI CCD observations of the semi-detached eclipsing binary EG Cep are presented. The observed light curves are analyzed with the Wilson-Devinney program and new geometrical and photometric elements are derived. These elements are used to compute the physical parameters of the system in order to study its evolutionary status.
The FU Orionis candidate V733 Cep was discovered by Roger Persson in 2004. The star is located in the dark cloud L1216 close to the Cepheus OB3 association. Because only a small number of FU Orionis stars have been detected to date, photometric and spectral studies of V733 Cep are of great interest. The studies of the photometrical variability of PMS stars are very important to the understanding of stellar evolution. The main purpose of our study is to construct a long-time light curve of V733 Cep. On the basis of BVRI monitoring we also study the photometric behavior of the star. We gather da…
We present and discuss the BVRI photometric evolution of Nova Del 2013 from the time of discovery, which occurred a few days before maximum brightness, to day +77, when the optically thick phase was over.
Results from BVRI photometric observations of the young stellar object V2492 Cyg collected during the period from August 2010 to December 2017 are presented. The star is located in the field of the Pelican Nebula and it was discovered in 2010 due to its remarkable increase in the brightness by more than 5 mag in R-band. According to the first hypothesis of the variability V2492 Cyg is an FUor candidate. During subsequent observations it was reported that the star shows the characteristics inherent to EXor- and UXor-type variables. The optical data show that during the whole time of observation…
Results from BVRI photometric observations of the pre-main sequence star V1704 Cyg collected during the time period from August 2010 to December 2017 are presented. The star is located in the star-forming HII region IC 5070 and it exhibits photometric variability in all-optical passbands. After analyzing the obtained data, V1704 Cyg is classified as a classical T Tauri star.
New results from long-term optical photometric observations of the pre-main sequence star GM Cep from UX Orionis type are reported. During ongoing photometric monitoring of the GM Cep four deep minimums in brightness are observed. The collected multicolour photometric data shows the typical of UXor variables colour reversal during the minimums in brightness. Recent $BVRI$ photometric observations of GM Cep have been collected from November 2014 to October 2020.
We carried out BVRI CCD photometric observations in the field of V582 Aur from 2009 August to 2013 February. We acquired high-, medium-, and low-resolution spectroscopy of V582 Aur during this period. To study the pre-outburst variability of the target and construct its historical light curve, we searched for archival observations in photographic plate collections. Both CCD and photographic observations were analyzed using a sequence of 14 stars in the field of V582 Aur calibrated in BVRI. The pre-outburst photographic observations of V582 Aur show low-amplitude light variations typical of T T…
New BVRI light curves of the eclipsing binary system 1SWASP J160156.04+202821.6 have been obtained with the 1.88-m telescope of Kottamia Astronomical Observatory (KAO), Egypt on June, 2013. New twenty times of minima of the system J1601 and new ephemeris have been reduced and derived from the present photometry. A preliminary determination of the geometric and photometric element parameters of the system J1601 has been derived.
Long-term BVRI photometric light curves of the pre-main sequence stars V977 Cep and V982 Cep during the period from 2000 October to 2016 August are presented. The stars are located in the vicinity of the reflection nebula NGC 7129. Our photometric data show that both stars exhibit strong photometric variability in all optical passbands, which is typical for Classical T Tauri stars. Using our observational data we analyze the reasons for the observed brightness variations. In the case of V977 Cep we identify previously unknown periodicity in its light curve.
Results from optical photometric observations of the pre-main sequence star GM Cep are reported in the paper. The star is located in the field of the young open cluster Trumpler 37 - a region of active star formation. GM Cep shows a large amplitude rapid variability interpreted as a possible outburst from EXor type in previous studies. Our data from BVRI CCD photometric observations of the star are collected from June 2008 to February 2011 in Rozhen observatory (Bulgaria) and Skinakas observatory (Crete, Greece). A sequence of sixteen comparison stars in the field of GM Cep was calibrated in t…
New photometric data from CCD multicolour BVRI observations of 14 pre-main sequence stars during the period from 2013 April to 2015 September are presented. The studied objects are located in the field of 'Gulf of Mexico' in the NGC 7000/IC 5070 star-forming complex. The stars from our study exhibit different types of photometric variability in all optical passbands. Using our long-term observations and data published by other authors, we tried to define the reasons for the observed brightness variations. On the basis of our new data previously unknown periodicity in the light curve of the sta…
Optical (BVRI) and infrared (JHK) photometry of the gamma-ray nova Nova Sco 2012 (V1324 Sco) is presented and the lightcurve reconstructed and discussed. An interstellar reddening E(B-V)=1.23 is derived. Dust begun to form at an early date in the nova, only one magnitude down and 20 days past maximum optical brightness and caused an extinction of at least 6 magnitudes in V band, that cleared some months later. This unusual early dust formation compromises the application of the magnitude at maximum versus rate of decline (MMRD) relations in estimating the distance to the nova.
Broadband $BVRI$ light curves of SN 2017eaw in NGC 6946 reveal the classic elements of a Type II-P supernova. The observations were begun on 16 May 2017 (UT), approximately 1 day after the discovery was announced, and the photometric monitoring was carried out over a period of nearly 600 days. The light curves show a well-defined plateau and an exponential tail which curves slightly at later times. An approximation to the bolometric light curve is derived and used to estimate the amount of $^{56}$Ni created in the explosion; from various approaches described in the literature, we obtain $M$($^…
I present BVRI photometry of the type IIP supernova 2013ej in M74 from 3 to 182 days after the explosion. These photometric measurements and spectroscopic data from the literature are combined via the expanding photosphere method to estimate the distance to the event, which is consistent with that derived by other methods. After correcting for extinction and adopting a distance modulus of (m - M) = 29.80 mag to M74, I derive absolute magnitudes M_B = -17.36, M_V = -17.47, M_R = -17.64 and M_I = -17.71. The differences between visual measurements and CCD V-band measurements of SN 2013ej are sim…
New BVRI CCD photometric observations of the contact system DF Hya have been obtained. The light curves were analyzed with the Wilson-Devinney code and new geometric and photometric elements were derived. Moreover, the light curve solution, with the assumption of a third light in the system, revealed the existence of a tertiary component around the eclipsing pair. The present results are compared with those of other recent studies.
We present results of new photometric observations of the contact binary system \astrobj{HI Pup} as well as the radial velocity curve of the system. Time series multicolour photometry was obtained at the South African Astronomical Observatory (SAAO) using the 1-m Cassegrain Telescope. We applied a simultaneous solution to the $BVRI$ light and radial velocity curves in order to determine the physical parameters of the system. From an analysis of the new multicolour data, the physical parameters were found to be $M_1=1.22M_{\odot}$, $M_2=0.23M_{\odot}$, $R_1=1.44R_{\odot}$, $R_2=0.67R_{\odot}$, …
The new multi-color $BVRI$ photometric light curves of the short-period eclipsing binary GSC 3576-0170 were obtained on two consecutive nights (October 5 and 6, 2009). With the 2003 version of Wilson-Devinney program, the precise photometric solutions are derived for the first time. The result shows that GSC 3576-0170 is a semi-detached binary system with a large temperature difference of approximately 1490 K. The light-curve distortions are further explained by a hot spot on the secondary component through mass transfer via a stream hitting the facing surface of the secondary component. By an…
We report the discovery of a large amplitude outburst from the young star HBC 722 (LkHA 188 G4) located in the region of NGC 7000/IC 5070. On the basis of photometric and spectroscopic observations, we argue that this outburst is of the FU Orionis type. We gathered photometric and spectroscopic observations of the object both in the pre-outburst state and during a phase of increase in its brightness. The photometric BVRI data (Johnson-Cousins system) that we present were collected from April 2009 to September 2010. To facilitate transformation from instrumental measurements to the standard sys…
The first photometric analysis of IR Cas was carried out based on the new observed BVRI light curves. The symmetric light curves and nearly flat secondary minimum indicate that very precise photometric results can be determined. We found that IR Cas is a near contact binary with the primary component filling its Roche lobe. An analysis of the O-C diagram based on all available times of light minimum reveals evidence for a periodic change with a semiamplitude of 0.0153 days and a period of 39.7 years superimposed on a secular decrease at a rate of dp/dt=-1.28(\pm0.09)\times10^{-7} d yr^{-1}. Th…
In this work we present detailed photometric results of the trapezium like galactic nearby OB clusters NGC 1502 and NGC 2169 carried out at the University Observatory Jena. We determined absolute $BVRI$ magnitudes of the mostly resolved components using Landolt standard stars. This multi colour photometry enables us to estimate spectral type and absorption as well as the masses of the components, which were not available for most of the cluster members in the literature so far, using models of stellar evolution. Furthermore, we investigated the optical spectrum of the components ADS 2984A and …
Results from long-term multicolor optical photometric observations of the pre-main sequence stars FHO 26, FHO 27, FHO 28, FHO 29 and V1929 Cyg collected during the period from June 1997 to December 2014 are presented. The objects are located in the dense molecular cloud L935, named "Gulf of Mexico", in the field between the North America and Pelican nebulae. All stars from our study exhibit strong photometric variability in all optical passbands. Using our BVRI observations and data published by other authors, we tried to define the reasons for the observed brightness variations. The presented…
CCD BVRI photometry is presented for the type Ic-BL Supernovae 2016coi and 2018ebt. The shape of the light curves for both objects is typical for this class of SNe. A change of brightness decline rate at about 100 days after maximum light is observed for SN 2016coi. The light curves of SN 2018ebt are best matched by those of SN Ic-BL 2002ap. For SN 2018ebt, we derived the dates and magnitudes of maximum light, rates of decline at late stages of evolution and presented evidence for extinction in the host galaxy being negligible.
This paper presents new CCD BVRI light curves of the newly discovered RS CVn eclipsing binary V1034 Her in 2009 and 2010, which shapes are different from the previous published results. They show asymmetric outside eclipse and we try to use a spot model to explain the phenomena. Using the Wilson-Devinney program with one-spot or two-spots model, photometric solutions of the system and starspot parameters were derived. Comparing the two results, it shows that the case of two spots is better successful in reproducing the light-curve distortions. For all the spot longitudes, it suggests that the …
Results from new BVRI photometric observations of the pre-MS stars V521 Cyg and FHO 27 collected during the period from February 2015 to July 2019 are presented. These stars are embedded in the LDN 935, dubbed "The Gulf of Mexico" in the active star-forming complex NGC 7000/IC 5070. Previous studies revealed them as variables with large amplitude brightness variations. Our new observations show that the stars continue to exhibit strong photometric variability and fading events in the brightness. On the basis of the new data received and the data available in the literature, we were able to spe…
We study the short and long-term variability of the spectroscopic binary SZ Pictoris, a southern RS CVn-type system. We used mid-resolution echelle spectra obtained at CASLEO spanning 18 years, and photometric data from the ASAS database V-band and from the Optical Robotic Observatory (BVRI-bands) for similar time lapses. We separated the composite spectra into those corresponding to both components, and we were able to determine accurate orbital parameters, in particular an orbital period of 4.95 days. We also observed a photometric modulation with half the orbital period, due to the elliptic…
We present new results from optical photometric and spectroscopic observations of the eruptive pre-main sequence star V2493 Cyg (HBC 722). The object has continued to undergo significant brightness variations over the past few months and is an ideal target for follow-up observations. We carried out CCD BVRI photometric observations in the field of V2493 Cyg ("Gulf of Mexico") from August 1994 to April 2012, i.e. at the pre-outburst states and during the phases of the outburst. We acquired high, medium, and low resolution spectroscopy of V2493 Cyg during the outburst. To study the pre-outburst …
We present the first detailed photometric analysis of ATO J108.6991+27.8306 (hereinafter as J108). The short-period close binary J108 was observed by the Nanshan 1 m Wide Field Telescope of the Xinjiang Astronomical Observatory. The obtained BVRI-band light curves were used to determine the photometric solution by using the 2003 version of the Wilson-Devinney code. J108 is a typical deep ( f > 50%), low mass ratio (q < 0.25) overcontact binary system with a mass ratio of q = 0.1501 and a fill-out factor of f = 50.1 %, suggesting that it is in the late evolutionary stage of contact binary syste…
We present the first extensive photometric results of CL Aur from our BVRI CCD photometry made on 22 nights from 2003 November through 2005 February. Fifteen new timings of minimum light were obtained. During the past 104 years, the orbital period has varied due to a periodic oscillation superposed on a continuous period increase. The period and semi-amplitude of the oscillation are about 21.6 yrs and 0.0133 d, respectively. This detail is interpreted as a light-travel-time effect due to a low-luminosity K-type star gravitationally bound to the CL Aur close system. Our photometric study indica…
The study of contemporaneous variations of the continuum flux and emission lines is of great importance to understand the different astrophysical processes at work in T Tauri stars. In this paper we present the results of a simultaneous $BVRI$ and H$α$ photometric monitoring, contemporaneous to medium-resolution spectroscopy of six T Tauri stars in the Taurus-Auriga star forming region. We have characterized the H$α$ photometric system using synthetic templates and the contemporaneous spectra of the targets. We show that we can achieve a precision corresponding to 2$-$3 Å in the H$α$ equivalen…
The main goal of this work is to characterize the mass accretion and ejection processes of the classical T Tauri star V354 Mon, a member of the young stellar cluster NGC 2264. In March 2008, photometric and spectroscopic observations of V354 Mon were obtained simultaneously with the CoRoT satellite, the 60 cm telescope at the Observatório Pico dos Dias (LNA - Brazil) equipped with a CCD camera and Johnson/Cousins BVRI filters, and the SOPHIE échelle spectrograph at the Observatoire de Haute-Provence (CNRS - France). The light curve of V354 Mon shows periodical minima (P = 5.26 +/- 0.50 days) t…
We have performed an optical spectroscopic and photometric search for young stellar objects associated with the molecular cloud Lynds 1340, and examined the structure of the cloud by constructing an extinction map, based on SDSS data. The new extinction map suggests a shallow, strongly fragmented cloud, having a mass of some 3700~Msun. Longslit spectroscopic observations of the brightest stars over the area of L1340 revealed that the most massive star associated with L1340 is a B4 type, about 5 solar mass star. The new spectroscopic and photometric data of the intermediate mass members led to …
We present and discuss accurate and densely mapped BVRI lightcurves of the neon Nova Mon 2012, supplemented by the evolution in Stromgren b and y bands and in the integrated flux of relevant emission lines. Our monitoring started with the optical discovery of the nova and extend to day +270, well past the end of the super-soft phase in X-rays. The nova displayed very smoothly evolving lightcurves. A bifurcation between y and V light-curves took place at the start of the SSS phase, and a knee developed toward the end of the SSS phase. The apparent magnitude of the nova at the unobserved optical…
Interferometric view into RT Pav's long secondary period. binary vs oscillatory convective modes
European Southern Observatory（欧洲南方天文台）；Research School of Astronomy and Astrophysics, Australian National University（澳大利亚国立大学天文学与天体物理研究学院）；Institut d’Astronomie et d’Astrophysique, Université Libre de Bruxelles (ULB)（布鲁塞尔自由大学天文学与天体物理学研究所）；Astronomical Observatory, University of Warsaw（华沙大学天文台）；Institute of Astronomy, KU Leuven（荷语鲁汶大学天体物理研究所）；Departamento de Física, Universidad de Santiago de Chile（智利圣地亚哥大学物理系）；Center for Interdisciplinary Research in Astrophysics and Space Exploration (CIRAS), USACH（智利圣地亚哥大学天体物理与空间探索跨学科研究中心）
Young double star V1318 Cyg, which is associated with a small isolated star-forming region around HAeBe star BD+40o4124, has very unusual photometric and spectral behavior. We present results of photometric and spectroscopic observations in the optical range. We carried out BVRI CCD photometric observations of V1318 Cyg from 2015 Sept. to 2017 July. For the same period we acquired medium- and low-resolution spectra. Observations were performed with the 2.6 m telescope. We analyze the historical light curve for V1318 Cyg and demonstrate that the southern component, V1318 Cyg S, after being rath…
We present differential $UBV$ photoelectric photometry obtained by Williamon of the short-period A-type W~UMa binary MW~Pav. With the Wilson-Devinney analysis program we obtained a simultaneous solution of these observations with the $UBV$ photometry of Lapasset (1977,1980), the $V$ measurements by the $ASAS$ program, and the double-lined radial velocity measurements of Rucinski & Duerbeck (2006). Our solution indicates that MW~Pav is in an overcontact state, where both components exceed their critical Roche lobes. We derive masses of $M_1 = 1.514 \pm 0.063 \, M_\sun$ and $M_2 = 0.327 \pm 0.01…
Post-shock regions (PSR) of polar cataclysmic variables produce most of their luminosity and give rise to high circular polarization in optical wavelengths and strong variability on the white dwarf rotation period, which are distinctive features of these systems. To investigate the polar candidate V348 Pav, we obtained a comprehensive observational set including photometric, polarimetric, and spectroscopic data, which was used to constrain the post-shock properties of the system. The object presents high circular polarization ($\sim30$ per cent) and high He II 4686A to H$~β$ line ratio, confir…
MASTER OT J120451.50+265946.6 (M12045), discovered by the MASTER Global Robotic Net, is a Type Ib supernova (SN) that exploded in NGC 4080. We present the {\it BVRI} photometric and spectroscopic observations upto $\sim$250 days since $B_{max}$. At the time of discovery the SN was a few weeks past maximum light and our observations capture the linearly declining light curve phase. M12045 declines faster as compared to SNe 1999dn and 2009jf at comparable epochs. Rigorous spectroscopic monitoring reveals that M12045 is a normal Type Ib SN. The analysis of the nebular phase spectra indicates that…
We present optical photometric and spectroscopic observations of the 1987A-like supernova (SN) 2009mw. Our $BVRI$ and $g'r'i'z'$ photometry covers 167 days of evolution, including the rise to the light curve maximum, and ends just after the beginning of the linear tail phase. We compare the observational properties of SN 2009mw with those of other SNe belonging to the same subgroup, and find that it shows similarities to several objects. The physical parameters of the progenitor and the SN are estimated via hydrodynamical modelling, yielding an explosion energy of $1$ foe, a pre-SN mass of $19…
We present BVRI and unfiltered light curves of 93 Type Ia supernovae (SNe Ia) from the Lick Observatory Supernova Search (LOSS) follow-up program conducted between 2005 and 2018. Our sample consists of 78 spectroscopically normal SNe Ia, with the remainder divided between distinct subclasses (three SN 1991bg-like, three SN 1991T-like, four SNe Iax, two peculiar, and three super-Chandrasekhar events), and has a median redshift of 0.0192. The SNe in our sample have a median coverage of 16 photometric epochs at a cadence of 5.4 days, and the median first observed epoch is ~4.6 days before maximum…
The main goal of this work is to determine the properties of the optical counterpart to the INTEGRAL source IGR J21343+4738, and study its long-term optical variability. We present optical photometric BVRI and spectroscopic observations covering the wavelength band 4000-7500 A. We find that the optical counterpart to IGR J21343+4738 is a V=14.1 B1IVe shell star located at a distance of ~8.5 kpc. The Halpha line changed from an absorption dominated profile to an emission dominated profile, and then back again into absorption. In addition, fast V/R asymmetries were observed once the disc develop…
