Jae‐Rim Koo

Gongju National University of Education

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Trends

Author Order

Document Type

Co-Authors

Kyeongsoo Hong

Korea Astronomy and Space Science Institute

Chung‐Uk Lee

Korea Astronomy and Space Science Institute

Jae Woo Lee

Korea Astronomy and Space Science Institute

Seung‐Lee Kim

Korea Astronomy and Space Science Institute

Jang-Ho Park

Korea Astronomy and Space Science Institute

Beomdu Lim

Korea Astronomy and Space Science Institute

Y. B. Kang

Korea Astronomy and Space Science Institute

Byeong‐Cheol Lee

Korea Astronomy and Space Science Institute

Dong-Joo Lee

Yeungnam University

Y. B. Kang

University of Crete

Cooperative Institutions

Korea Astronomy and Space Science Institute

Korea University of Science and Technology

Chungbuk National University

Chungnam National University

Max Planck Institute for Astronomy

Center for Astrophysics Harvard & Smithsonian

Osservatorio Astrofisico di Catania

Aarhus University

Kyungpook National University

University of Sydney

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Field

Absolute Properties of the Eclipsing γ Dor Star V404 Lyrae

The Astronomical Journal (2019)

Jae Woo Lee Kyeongsoo Hong Jae‐Rim Koo Jang-Ho Park

We present the first high-resolution spectra for the eclipsing binary V404 Lyr showing $\gamma$ Dor pulsations, which we use to study its absolute properties. By fitting models to the disentangling spectrum of the primary star, we found that it has an effective temperature of $T_{\rm eff,1}=7,330 \pm 150$ K and a rotational velocity of $v_1\sin$$i=148\pm18$ km s$^{-1}$. The simultaneous analysis of our double-lined radial velocities and the pulsation-subtracted ${\it Kepler}$ data gives us accurate stellar and system parameters of V404 Lyr. The masses, radii, and luminosities are $M_1$ = 2.17$\pm$0.06 M$_\odot$, $R_1$ = 1.91$\pm$0.02 R$_\odot$, and $L_1$ = 9.4$\pm$0.8 L$_\odot$ for the primary, and $M_2$ = 1.42$\pm$0.04 M$_\odot$, $R_2$ = 1.79$\pm$0.02 R$_\odot$, and $L_2$ = 2.9$\pm$0.2 L$_\odot$ for the secondary. The tertiary component orbiting the eclipsing pair has a mass of $M_{\rm 3b}$ = 0.71$\pm$0.15 $M_\odot$ in an orbit of $P_{\rm 3b}$ = 642$\pm$3 days, $e_{\rm 3b}$ = 0.21$\pm$0.04, and $a_{\rm 3b}$ = 509$\pm$2 R$_\odot$. The third light of $l_3=4.1\pm0.2\%$ could be partly attributable to the K-type circumbinary object. By applying a multiple frequency analysis to the eclipse-subtracted light residuals, we detected 45 frequencies with signal to noise amplitude ratios larger than 4.0. Identified as independent pulsation modes, seven frequencies ($f_1-f_6$, $f_9$), their new pulsation constants, and the location in the Hertzsprung-Russell diagram indicate that the pulsating primary is a $\gamma$ Dor-type variable star.

Star (game theory)

Eclipse

10.3847/1538-3881/ab59ce

Cite

Citations (17)

KIC 4739791: A NEW R CMa-TYPE ECLIPSING BINARY WITH A PULSATING COMPONENT

The Astronomical Journal (2016)

Jae Woo Lee Seung‐Lee Kim Kyeongsoo Hong Jae‐Rim Koo Chung‐Uk Lee

The Kepler light curve of KIC 4739791 exhibits partial eclipses, the inverse O'Connell effect, and multiperiodic pulsations. Including a starspot on either of the binary components, the light-curve synthesis indicates that KIC 4739791 is in detached or semi-detached configuration with both a short orbital period and a low mass ratio. Multiple frequency analyses were performed in the light residuals after subtracting the binarity effects from the original Kepler data. We detected 14 frequencies: 6 in the low-frequency region (0.1−2.3 days−1) and 8 in the high-frequency region (18.2−22.0 days−1). Among these, six high frequencies with amplitudes of 0.62−1.97 mmag were almost constant over time for 200 days. Their pulsation periods and pulsation constants are in the ranges of 0.048−0.054 days and 0.025−0.031 days, respectively. In contrast, the other frequencies may arise from the alias effects caused by the orbital frequency or combination frequencies. We propose that KIC 4739791 is a short-period R CMa binary with the lowest mass ratio in the known classical Algols and that its primary component is a δ Sct pulsating star. Only four R CMa stars have been identified, three of which exhibit δ Sct-type oscillations. These findings make KIC 4739791 an attractive target for studies of stellar interior structure and evolution.

Starspot

Mass ratio

Orbital period

Low Mass

Star (game theory)

10.3847/0004-6256/151/2/25

Cite

Citations (15)

VizieR Online Data Catalog: Kepler light curve of the EB star KIC 9532219 (Lee+, 2016)

yCat (2016)

J. W. Lee Kyeongsoo Hong Jae‐Rim Koo J. H. Park

Star (game theory)

Source

Cite

Citations (0)

Absolute Dimensions and Evolutionary Status of the Semi-detached Algol W Ursae Minoris

The Astronomical Journal (2018)

Jang-Ho Park Kyeongsoo Hong Jae‐Rim Koo Jae Woo Lee Chun‐Hwey Kim

Double-lined eclipsing binaries allow accurate and direct determination of fundamental parameters such as mass and radius for each component, and they provide important constraints on the stellar structure and evolution models. In this study, we aim to determine a unique set of binary parameters for the Algol system W UMi and to examine its evolutionary status. New high-resolution time-series spectroscopic observations were carried out during 14 nights from April 2008 to March 2011, and a total of 37 spectra were obtained using the Bohyunsan Optical Echelle Spectrograph. We measured the radial velocities (RVs) for both components, and the effective temperature of the primary star was found to be $T_{\rm eff,1}$ = 9310 $\pm$ 90 K by a comparison of the observed spectra and the Kurucz models. The physical parameters of W UMi were derived by an analysis of our RV data together with the multi-band light curves of Devinney et al. (1970). The individual masses, radii, and luminosities of both components are $M_1$ = 3.68 $\pm$ 0.10 M$_\odot$ and $M_2$ = 1.47 $\pm$ 0.04 M$_\odot$, $R_1$ = 3.88 $\pm$ 0.03 R$_\odot$ and $R_2$ = 3.13 $\pm$ 0.03 R$_\odot$, and $L_1$ = 102 $\pm$ 1 L$_\odot$ and $L_2$ = 7.3 $\pm$ 0.1 L$_\odot$, respectively. A comparison of these parameters with theoretical stellar models showed that the primary component lies in the main-sequence band, while the less massive secondary is noticeably evolved. The results indicate that the initially more massive star became the present secondary by losing most of its own mass via mass transfer to the companion (present primary).

Effective temperature

Primary component

Radial velocity

Star (game theory)

10.3847/1538-3881/aaab65

Cite

Citations (2)

Physical Properties of the Transiting Planetary System TrES-3

Publications of the Astronomical Society of Japan (2011)

Jae Woo Lee Jae‐Hyuck Youn Seung‐Lee Kim Chung‐Uk Lee Jae‐Rim Koo

We present four new transits of the planetary system TrES-3 observed between 2009 May and 2010 June. Among these, the third transit by itself indicates possible evidence for brightness disturbance, which might be the result of the planet blocking a cool starspot on the stellar surface. A total of 109 transit times, including our measurements, were used to determine the improved ephemeris with a transit epoch of 2454185.910944$\pm$0.000072 HJED and an orbital period of 1.30618700$\pm$0.00000015 d. We analyzed the transit light curves using the JKTEBOP code and adopting the quadratic limb-darkening law. In order to derive the physical properties of the TrES-3 system, the transit parameters are combined with the empirical relations from eclipsing binary stars and stellar evolutionary models. The stellar mass and radius obtained from a calibration using $T_A$, log $\rho_{\rm A}$ and [Fe/H] are consistent with those from the isochrone analysis. We found that the exoplanet TrES-3b has a mass of 1.93$\pm$0.07 M$_{\rm Jup}$, a radius of 1.30$\pm$0.04 R$_{\rm Jup}$, a surface gravity of log $g_{\rm b}$=3.45$\pm$0.02, a density of 0.82$\pm$0.06 $\rho_{\rm Jup}$, and an equilibrium temperature of 1641$\pm$23 K. The results are in good agreement with theoretical models for gas giant planets.

Starspot

Ephemeris

Surface gravity

Effective temperature

Hot Jupiter

Orbital period

Subgiant

10.1093/pasj/63.1.301

Cite

Citations (21)

Origin and Status of Low-Mass Candidate Hypervelocity Stars

Journal of The Korean Astronomical Society (2019)

Bum-Suk Yeom Young Sun Lee Jae‐Rim Koo Timothy C. Beers Young Kwang Kim

We present an analysis of the chemical abundances and kinematics of six low-mass dwarf stars, previously claimed to be candidate hypervelocity stars (HVSs). We obtained moderate-resolution ($R\sim$ 6000) spectra of these stars to estimate their abundances of several chemical elements (Mg, Si, Ca, Ti, Cr, Fe, and Ni), and derived their space velocity components and orbital parameters using proper motions from \gaia Data Release 2. All six stars are shown to be bound to the Milky Way, and in fact are not even considered high-velocity stars with respect to the Galactic rest frame. Nevertheless, we attempt to characterize their parent Galactic stellar components by simultaneously comparing their abundance patterns and orbital parameters with those expected from various Galactic stellar components. We find that two of our program stars are typical disk stars. For four of the program stars, even though their kinematic probabilistic membership assignment suggests membership in the Galactic disk, based on their distinct orbital properties and chemical characteristics, we cannot rule out the exotic origins of these objects, as follows. Two stars appear to be runaway stars from the Galactic disk. One program star has possibly been accreted from a disrupted dwarf galaxy or dynamically heated from a birthplace in the Galactic bulge. The last object may be either a runaway disk star or has been dynamically heated. Spectroscopic follow-up observations with higher resolution for these curious objects will provide a better understanding of their origin.

Thick disk

Source

Cite

Citations (1)

1SWASP J093010.78+533859.5: A POSSIBLE HIERARCHICAL QUINTUPLE SYSTEM

The Astronomical Journal (2014)

Jae‐Rim Koo Jae Woo Lee Byeong‐Cheol Lee Seung‐Lee Kim Chung‐Uk Lee

Among quadruples or higher multiplicity stars, only a few doubly eclipsing binary systems have been discovered. They are important targets for understanding the formation and evolution of multiple stellar systems because we can obtain accurate stellar parameters from photometric and spectroscopic studies. We present the observational results of this kind of rare object, 1SWASP J093010.78+533859.5, for which the doubly eclipsing feature had been detected previously from the SuperWASP photometric archive. Individual point-spread function photometry for two objects with a separation of about 19 was performed for the first time in this study. Our time-series photometric data confirms the finding of Lohr et al. that the bright object A is an Algol-type detached eclipsing binary and the fainter B is a W UMa-type contact eclipsing. Using high-resolution optical spectra, we obtained well-defined radial velocity variations of system A. Furthermore, stationary spectral lines were detected that must have originated from a further, previously unrecognized stellar component. It was confirmed by the third object contribution from the light-curve analysis. No spectral feature of system B was detected, probably due to motion blur by long exposure times. We obtained the binary parameters and the absolute dimensions of systems A and B from light-curve synthesis with and without radial velocities, respectively. The primary and secondary components of system A have a spectral type of K1 and K5 main sequences, respectively. Two components of system B have nearly the same type of K3 main sequence. Light variations for both binaries are satisfactorily modeled by using two-spot models with one starspot on each component. We estimated the distances to systems A and B individually. Two systems may have similar distances of about 70 pc and seem to be gravitationally bound with a separation of about 130 AU. In conclusion, we suggest that 1SWASP J093010.78+533859.5 is a quintuple stellar system with a hierarchical structure of a triple system A(ab)c and a binary system B(ab).

Radial velocity

Contact binary

10.1088/0004-6256/147/5/104

Cite

Citations (31)

VizieR Online Data Catalog: Three binary systems in the Large Magellanic Cloud (Hong+, 2019)

VizieR Online Data Catalog (2019)

Kyeongsoo Hong J. W. Lee S. L. Kim Jae‐Rim Koo J. H. Park

Large Magellanic Cloud

Source

Cite

Citations (0)