A5031500910- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Adaptive optics and wavefront sensing
- History and Developments in Astronomy
- Gamma-ray bursts and supernovae
- Solar and Space Plasma Dynamics
- Inertial Sensor and Navigation
- Space Satellite Systems and Control
- Astrophysical Phenomena and Observations
- Dynamics and Control of Mechanical Systems
- Adaptive Control of Nonlinear Systems
- Infrared Target Detection Methodologies
- Particle Accelerators and Free-Electron Lasers
- Engineering Applied Research
- Historical Astronomy and Related Studies
- Superconducting Materials and Applications
- Geophysics and Gravity Measurements
- Planetary Science and Exploration
- Spacecraft and Cryogenic Technologies
- Advanced Fiber Laser Technologies
- Atmospheric Ozone and Climate
- Aerospace Engineering and Control Systems
Chungbuk National University
2013-2023
Astronomy and Space
1995-2010
Institute for Basic Science
2003-2009
Korea Astronomy and Space Science Institute
1989-2006
Villanova University
2005
Yonsei University
1987-1991
For the very short period subdwarf B eclipsing binary HW Vir, we present new CCD photometry made from 2000 through 2008. In order to obtain consistency of parameters, our light curves, showing sharp eclipses and a striking reflection effect, were analyzed simultaneously with previously published radial velocity data. The secondary star parameters M2 = 0.14 M☉, R2 0.18 R☉, T2 3084 K are consistent those an M6-7 main-sequence star. A credibility issue regarding bolometric corrections is...
Abstract High precision CCD observations of six totally eclipsing contact binaries were presented and analyzed. It is found that only one target an A-type binary (V429 Cam), while the others are W-type ones. By analyzing times light minima, we discovered two them exhibit secular period increase three manifest long-term decrease. For V1033 Her, a cyclic variation superimposed on was discovered. comparing Gaia distances with those calculated by absolute parameters 173 binaries, distance can be...
The cut-off mass ratio is under debate for contact binaries. In this paper, we present the investigation of two binaries with ratios close to low limit. It found that VSX J082700.8+462850 (hereafter J082700) and 1SWASP J132829.37+555246.1 J132829) are both less than 0.1 ($q\sim0.055$ J082700, $q\sim0.089$ J132829). J082700 a shallow binary degree $\sim$19%, J132829 deep system fillout factor $\sim$70%. $O-C$ diagram analysis indicated systems manifest long-term period decrease. addition,...
In this paper, we present the first light curve synthesis and orbital period change analysis of nine contact binaries around short limit. It is found that all these systems are W-subtype binaries. One them a medium system while others shallow ones. Four manifest obvious O'Connell effect explained by dark spot or hot on one component stars. Third was detected in three systems. By investigating variations, four targets display secular decrease exhibit long-term increase. The more likely caused...
A comprehensive catalog of 623 galactic eclipsing binary (EB) systems with eccentric orbits is presented more than 2830 times minima determined from the archived photometric data by various sky-survey projects and new measurements. The are divided into two groups according to whether individual system has a GCVS name or not. All in both further classified three categories (D, A, A+III) on basis their eclipse timing diagrams: 453 D showing just constantly displaced secondary minima, 139...
18 new times of minimum light for YY Eri were determined from relatively or unpublished photoelectric observations Korea, New Zealand, and Turkey, added to a collection all other minima available us. These data then intensively analyzed, by reference an 0-C diagram, deduce the general form period variation Eri. The diagram could be either quasi-sinusoidal superposed on upward parabola, set abrupt changes. If changes, they appear have occurred alternately in pattern two increases following...
New charge-coupled device photometric observations of the W UMa-type binary BX Pegasi (BX Peg) were collected on four nights from 1999 October to 2000 September. The light curve was covered completely in each season. Seven new times minimum determined. It found that orbital period system has varied recently a sinusoidal way, superimposed downward parabolic variation. long-term decrease rate is deduced as dP/dt=−8.62 or 9.59 × 10−8 d yr−1, which can be interpreted either mass transfer more...
We report the discovery of a multiple system with quadruple-lined spectrum and double eclipsing feature. Our photometric high-resolution spectroscopic data show that V994 Herculis (V994 Her; ADS 11373 AB) is composed two pairs double-lined binaries, which we designate as A B. System consists B8V+A0V binary an orbital period 2.083 264 d B A2V+A4V 1.420 033 d. light curves both them have detached configuration. derive masses radii four components (Aa, Ab, Ba Bb) from synthetic analyses radial...
We conduct a systematic investigation of the microlensing data collected during previous observation seasons for purpose reanalyzing anomalous lensing events with no suggested plausible models. find that two OGLE-2018-BLG-0584 and KMT-2018-BLG-2119 cannot be explained usual models based on either binary-lens single-source (2L1S) or single-lens binary-source (1L2S) interpretation. test feasibility explaining light curves more sophisticated by adding an extra lens (3L1S model) source (2L2S...
We present the full VRI light curves and times of minima TY UMa to provide a complete photometric solution long-term trend period variation. The show high degree asymmetry (the O'Connell effect). maxima at 0.25 phase (Max I) are 0.021, 0.015, 0.020 mag fainter than those 0.75 II) in V, R, I, respectively. has varied sinusoidal way, superimposed on upward parabolic secularly increasing rate is deduced as 1.83 s per century (P˙/P=5.788×10−10 d d−1). variation about 57.4 yr. spot model been...
Abstract We present the analysis of planetary microlensing event MOA-2016-BLG-319. The light curve is characterized by a brief (∼3 days) anomaly near peak produced minor-image perturbations. From modeling, we find two distinct solutions that describe observed almost equally as well. investigation lens-system configurations, confusion in lensing solution caused degeneracy between resulting from source passages on different sides caustic. These degeneracies can be severe for major-image...
We present the analysis of microlensing event OGLE-2016-BLG-1227. The light curve this short-duration appears to be a single-lens affected by severe finite-source effects. Analysis based on single-source (1L1S) modeling yields very small values timescale, $t_{\rm E}\sim 3.5$ days, and angular Einstein radius, $\theta_{\rm 0.009$ mas, making lens candidate free-floating planet. Close inspection reveals that 1L1S solution leaves residuals with amplitude $\Delta I\lesssim 0.03$ mag. find are...
A total of 1637 BVR CCD observations the overcontact binary ER Ori are used as basis for new light curves, including first red one. From these measurements, timings minimum have been calculated. The complex period variation can be sorted into a linear improvement, secular increase considerable magnitude, and 50 year cyclical component. This latter is discussed in terms light-time contribution from bound third star, which finds some support Hipparcos results. curves were synthesized using...
We present complete VRI light curves of the contact binary CE Leo and provide detailed photometric solutions, as well an analysis its period variation. A total 73 times minima over 50 years, including our observations, were used for study. The complex variation can be sorted into a linear improvement, P = 0.30342771 days, secular increase at rate /P +3.05 × 10-7 days yr-1, 22.6 ± 0.5 yr periodic component. ∼22.6 in O-C residuals most likely arises from light-travel time effect low-mass (m3 ∼...
Numerous new CCD measures of the cool overcontact binary SS Arietis are compiled into six well-covered light curves. The confusing history binary's period variability is laid out in order to consider diverse interpretations that have been presented previously. It concluded activity can be ascribed no fewer than three separate causes. There some little support for a magnetic cycle functioning phase with one components variability. curves from 1996 responded satisfactorily modern synthesis...
Abstract We obtained CCD photometric observations of the Algol-type semidetached binary XX Cephei (XX Cep) during 15 nights from 2002 September 17 to 2003 February 2, and also on 2005 January 21. Except for those data taken last night concentrated observing season, 3881 measurements were over an interval only 106 nights. From these data, four new times minimum light calculated. The (O− C) diagram formed all available timings, thus orbital period system, can be partly represented as a beat...
We present the first extensive photometric results of CL Aur from our BVRI CCD photometry made on 22 nights 2003 November through 2005 February. Fifteen new timings minimum light were obtained. During past 104 years, orbital period has varied due to a periodic oscillation superposed continuous increase. The and semi-amplitude are about 21.6 yrs 0.0133 d, respectively. This detail is interpreted as light-travel-time effect low-luminosity K-type star gravitationally bound close system. Our...
A photometric study of BD And was made through the analysis two sets new BVR light curves. The curves with migrating waves outside eclipse show that is a short-period RS CVn-type binary star. all available timings reveals orbital period has varied in strictly cyclical way 9.2 yr. periodic variation most likely arises from light-time effect due to tertiary moving highly elliptical orbit (e3 = 0.76). Applegate mechanism could not operate properly eclipsing pair. were modeled large spots on...
Aims. Microlensing planets occurring on faint-source stars can escape detection due to their weak signals. Occasionally, detections of such are not reported the difficulty extracting high-profile scientific issues detected planets. Methods. For solid demographic census microlensing planetary systems based a complete sample, we investigate data obtained in 2016 and 2017 seasons search for signals lensing events. From this investigation, find four unpublished planets: KMT-2016-BLG-2364Lb,...
We aim to find missing microlensing planets hidden in the unanalyzed lensing events of previous survey data. For this purpose, we conduct a systematic inspection high-magnification events, with peak magnifications $A_{\rm peak}\gtrsim 30$, data collected from high-cadence surveys and before 2018 season. From investigation, identify an anomaly light curve event KMT-2018-BLG-1025. The analysis indicates that is caused by very low mass-ratio companion lens. three degenerate solutions, which...
This paper presents the first analysis of contact binary TYC 3801-1529-1. We observed four sets multiple bands complete light curves and one set radial velocity curve primary component. Based on a simultaneous investigation our TESS curve, we found that 3801-1529-1 is an extremely low-mass-ratio, medium with $q=0.0356$, contribution third at level about 10<!PCT!>. Its mass ratio lower than V1187 Her, making lowest mass-ratio ever in universe. The 2022 are asymmetric, which aptly...
We present new multicolor charge-coupled device (CCD) photometry for the short-period close binary V432 Per, made on six nights between 2006 February and December. A period study of system, based all published newly observed times minimum light, reveals that orbital has varied as a beat effect due to combination secular increase sinusoidal variation, with 35.3 yr semi-amplitude 0.0104 d. The continuous can be interpreted mass transfer from less massive secondary star more primary component...
We investigate the gravitational microlensing event KMT-2019-BLG-1715, of which light curve shows two short-term anomalies from a caustic-crossing binary-lensing curve: one with large deviation and other small deviation. identify five pairs solutions, in are explained by adding an extra lens or source component addition to base binary-lens model. resolve degeneracies applying method, measured flux ratio between first second stars is compared deduced radii. Applying this method leaves single...
With the aim of interpreting anomalous lensing events with no suggested models, we conducted a project reinvestigating microlensing data in and before 2019 season. In this work, report multi-planet system OGLE-2019-BLG-0468L found from project. The light curve event OGLE-2019-BLG-0468, which consists three distinctive anomaly features, could not be explained by usual binary-lens or binary-source interpretation. We find solution explaining all features triple-lens interpretation, lens is...