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New light‐travel time models and orbital stability study of the proposed planetary system HU Aquarii
Hinse, T. C.,Lee, J. W.,Goź,dziewski, K.,Haghighipour, N.,Lee, C.‐,U.,Scullion, E. M. Blackwell Publishing Ltd 2012 Monthly notices of the Royal Astronomical Society Vol.420 No.4
<P><B>ABSTRACT</B></P><P>In this work we propose a new orbital architecture for the two proposed circumbinary planets around the polar eclipsing binary HU Aquarii. We base the new two‐planet, light‐travel time model on the result of a Monte Carlo simulation driving a least‐squares Levenberg–Marquardt minimization algorithm on the observed eclipse egress times. Our best‐fitting model with <IMG src='/wiley-blackwell_img/equation/MNR_20283_mu1.gif' alt ='inline image'/> resulted in high final eccentricities for the two companions leading to an unstable orbital configuration. From a large ensemble of initial guesses, we examined the distribution of final eccentricities and semimajor axes for different <IMG src='/wiley-blackwell_img/equation/MNR_20283_mu2.gif' alt ='inline image'/> parameter intervals and encountered qualitatively a second population of best‐fitting parameters. The main characteristic of this population is described by low‐eccentric orbits favouring long‐term orbital stability of the system. We present our best‐fitting model candidate for the proposed two‐planet system and demonstrate orbital stability over one million years using numerical integrations.</P>
Photometric Defocus Observations of Transiting Extrasolar Planets
HINSE TOBIAS CORNELIUS,한원용,윤요나,이정욱,김용기,김천휘 한국우주과학회 2015 Journal of Astronomy and Space Sciences Vol.32 No.1
We have carried out photometric follow-up observations of bright transiting extrasolar planets using the CbNUOJ 0.6m telescope. We have tested the possibility of obtaining high photometric precision by applying the telescope defocustechnique, allowing the use of several hundred seconds in exposure time for a single measurement. We demonstrate thatthis technique is capable of obtaining a root-mean-square scatter of sub-millimagnitude order over several hours for a V~10 host star, typical for transiting planets detected from ground-based survey facilities. We compared our results withtransit observations from a telescope operated in in-focus mode. High photometric precision was obtained due to thecollection of a larger amount of photons, resulting in a higher signal compared to other random and systematic noisesources. Accurate telescope tracking is likely to further contribute to lowering systematic noise by exposing the same pixelson the CCD. Furthermore, a longer exposure time helps reduce the effect of scintillation noise which otherwise has asignificant effect for small-aperture telescopes operated in in-focus mode. Finally we present the results of modelling fourlight-curves in which a root-mean-square scatter of 0.70 to 2.3 milli-magnitudes was achieved.
THE PROPOSED QUADRUPLE SYSTEM SZ HERCULIS: REVISED LITE MODEL AND ORBITAL STABILITY STUDY
Hinse, Tobias Cornelius,Goź,dziewski, Krzysztof,Lee, Jae Woo,Haghighipour, Nader,Lee, Chung-Uk American Institute of Physics 2012 The Astronomical journal Vol.144 No.2
<P>In a recent study, Lee et al. presented new photometric follow-up timing observations of the semidetached binary system SZ Herculis and proposed the existence of two hierarchical cirumbinary companions. Based on the light-travel time effect, the two low-mass M-dwarf companions are found to orbit the binary pair on moderate to high eccentric orbits. The derived periods of these two companions are close to a 2:1 mean-motion orbital resonance. We have studied the stability of the system using the osculating orbital elements as presented by Lee et al. Results indicate an orbit-crossing architecture exhibiting short-term dynamical instabilities leading to the escape of one of the proposed companions. We have examined the system's underlying model parameter space by following a Monte Carlo approach and found an improved fit to the timing data. A study of the stability of our best-fitting orbits also indicates that the proposed system is generally unstable. If the observed anomalous timing variations of the binary period is due to additional circumbinary companions, then the resulting system should exhibit a long-term stable orbital configuration much different from the orbits suggested by Lee et al. We, therefore, suggest that based on Newtonian-dynamical considerations, the proposed quadruple system cannot exist. To uncover the true nature of the observed period variations of this system, we recommend future photometric follow-up observations that could further constrain eclipse-timing variations and/or refine light-travel time models.</P>
Using Light Travel Time Effect to Detect Circumbinary Planets with Ground-Based Telescopes
Hinse, Tobias Cornelius 한국천문학회 2012 天文學會報 Vol.37 No.2
In the past few years, two-planet circumbinary systems (e.g., HW Vir, NN Ser, DP Leo and HU Aqr) have been detected around short-period eclipsing binaries using ground-based telescopes. The existence of these planets has been inferred by interpreting the O-C variations of the mid-eclipse times. We have tested the orbital stability of these systems and propose to use Light Travel Time Effect (LITE) to detect such circumbinary planets from the ground. We generated synthetically the LITE signal of a two-planet circumbinary system with the aim to apply an analytic LITE model to recover the underlying synthetic system. To mimic a degree of realism inherent to ground-based observations, we added to the synthetic LITE data white noise with a Gaussian distribution and sampled the synthetic LITE signal randomly. We successfully recovered the original system demonstrating that two-planet circumbinary systems can be detected using ground-based telescopes, provided the timing measurements of the mid-eclipses are sufficiently accurate and the observing baseline is long enough to ensure a sufficient coverage of all involved periods. We used HU Aqr as a test system and applied our model to its proposed planetary bodies considering near-circular orbits. We present the results of our calculations and discuss the LITE-detectability of a HU Aqr-like system.
An Orbital Stability Study of the Proposed Companions of SW Lyncis
Hinse, T.C.,Horner, Jonathan,Wittenmyer, Robert A. The Korean Space Science Society 2014 Journal of Astronomy and Space Sciences Vol.31 No.3
We have investigated the dynamical stability of the proposed companions orbiting the Algol type short-period eclipsing binary SW Lyncis (Kim et al. 2010). The two candidate companions are of stellar to substellar nature, and were inferred from timing measurements of the system's primary and secondary eclipses. We applied well-tested numerical techniques to accurately integrate the orbits of the two companions and to test for chaotic dynamical behavior. We carried out the stability analysis within a systematic parameter survey varying both the geometries and orientation of the orbits of the companions, as well as their masses. In all our numerical integrations we found that the proposed SW Lyn multi-body system is highly unstable on time-scales on the order of 1000 years. Our results cast doubt on the interpretation that the timing variations are caused by two companions. This work demonstrates that a straightforward dynamical analysis can help to test whether a best-fit companion-based model is a physically viable explanation for measured eclipse timing variations. We conclude that dynamical considerations reveal that the proposed SW Lyncis multi-body system most likely does not exist or the companions have significantly different orbital properties from those conjectured in Kim et al. (2010).
Photometric Defocus Observations of Transiting Extrasolar Planets
Hinse, Tobias C.,Han, Wonyong,Yoon, Joh-Na,Lee, Chung-Uk,Kim, Yong-Gi,Kim, Chun-Hwey The Korean Space Science Society 2015 Journal of Astronomy and Space Sciences Vol.32 No.1
We have carried out photometric follow-up observations of bright transiting extrasolar planets using the CbNUOJ 0.6 m telescope. We have tested the possibility of obtaining high photometric precision by applying the telescope defocus technique, allowing the use of several hundred seconds in exposure time for a single measurement. We demonstrate that this technique is capable of obtaining a root-mean-square scatter of sub-millimagnitude order over several hours for a V~10 host star, typical for transiting planets detected from ground-based survey facilities. We compared our results with transit observations from a telescope operated in in-focus mode. High photometric precision was obtained due to the collection of a larger amount of photons, resulting in a higher signal compared to other random and systematic noise sources. Accurate telescope tracking is likely to further contribute to lowering systematic noise by exposing the same pixels on the CCD. Furthermore, a longer exposure time helps reduce the effect of scintillation noise which otherwise has a significant effect for small-aperture telescopes operated in in-focus mode. Finally we present the results of modelling four light-curves in which a root-mean-square scatter of 0.70 to 2.3 milli-magnitudes was achieved.
Tobias C. Hinse,김우균,안상현,이재근,박준형,이영우,정우정,우상민 한국천문학회 2017 天文學論叢 Vol.32 No.3
We give a detailed description of the installation and operation of a double-station meteor detectionsystem which formed part of a research & education project between Korea Astronomy Space ScienceInstitute (KASI) and Daejeon Science Highschool. A similar system is currently not existing in SouthKorea. A total of six light-sensitive CCD cameras were installed with three cameras at SOAO and threecameras at BOAO observatory. A double-station observation of a meteor event enables the determinationof the three-dimensional heliocentric orbit in space. This project was initiated in response to the Jinjureball event in March 2014. The cameras were installed in October/November 2014. The two stationsare identical in hardware as well as software. Each station employes sensitive \Watec-902H2" cameras incombination with relatively fast f/1.2 lenses. Various elds of views were used for measuring di erencesin detection rates of meteor events. We employed the SonotaCo UFO software suite for meteor detectionand their subsequent analysis. The system setup as well as installation/operation experience is describedand rst results are presented. We also give a brief overview of historic as well as recent meteor (fall)detections in South Korea. For more information please consult http://meteor.kasi.re.kr.