Journal of Astronomy and Space Sciences最新文献_第10页

Thick Accretion Disk and Its Super Eddington Luminosity around a Spinning Black Hole 旋转黑洞周围的厚吸积盘及其超级爱丁顿光度

IF 0.5

Journal of Astronomy and Space Sciences Pub Date : 2020-02-24 DOI: 10.5140/JASS.2021.38.1.39

Uicheol Jang, Hongsu Kim, Y. Yi

引用次数: 1

Development of a Period Analysis Algorithm for Detecting Variable Stars in Time-Series Observational Data 时间序列观测数据中变星探测周期分析算法的发展

IF 0.5

Journal of Astronomy and Space Sciences Pub Date : 2019-12-01 DOI: 10.5140/JASS.2019.36.4.283

Dong-Heun Kim, Yonggi Kim, Joh-Na Yoon, Hong-Seo Im

{"title":"Development of a Period Analysis Algorithm for Detecting Variable Stars in\u0000 Time-Series Observational Data","authors":"Dong-Heun Kim, Yonggi Kim, Joh-Na Yoon, Hong-Seo Im","doi":"10.5140/JASS.2019.36.4.283","DOIUrl":"https://doi.org/10.5140/JASS.2019.36.4.283","url":null,"abstract":"The purpose of this study was to develop a period analysis algorithm for\u0000 detecting new variable stars in the time-series data observed by charge coupled device\u0000 (CCD). We used the data from a variable star monitoring program of the CBNUO. The R\u0000 filter data of some magnetic cataclysmic variables observed for more than 20 days were\u0000 chosen to achieve good statistical results. World Coordinate System (WCS) Tools was used\u0000 to correct the rotation of the observed images and assign the same IDs to the stars\u0000 included in the analyzed areas. The developed algorithm was applied to the data of DO\u0000 Dra, TT Ari, RXSJ1803, and MU Cam. In these fields, we found 13 variable stars, five of\u0000 which were new variable stars not previously reported. Our period analysis algorithm\u0000 were tested in the case of observation data mixed with various fields of view because\u0000 the observations were carried with 2K CCD as well as 4K CCD at the CBNUO. Our results\u0000 show that variable stars can be detected using our algorithm even with observational\u0000 data for which the field of view has changed. Our algorithm is useful to detect new\u0000 variable stars and analyze them based on existing time-series data. The developed\u0000 algorithm can play an important role as a recycling technique for used data","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":"27 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82746483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Normalized Cross-Correlations of Solar Cycle and Physical Characteristics of Cloud 太阳周期与云物理特征的归一化相互关系

IF 0.5

Journal of Astronomy and Space Sciences Pub Date : 2019-12-01 DOI: 10.5140/JASS.2019.36.4.225

Heon-Young Chang

{"title":"Normalized Cross-Correlations of Solar Cycle and Physical Characteristics of\u0000 Cloud","authors":"Heon-Young Chang","doi":"10.5140/JASS.2019.36.4.225","DOIUrl":"https://doi.org/10.5140/JASS.2019.36.4.225","url":null,"abstract":"We explore the associations between the total sunspot area, solar north-south\u0000 asymmetry, and Southern Oscillation Index and the physical characteristics of clouds by\u0000 calculating normalized cross-correlations, motivated by the idea that the galactic\u0000 cosmic ray influx modulated by solar activity may cause changes in cloud coverage, and\u0000 in turn the Earth’s climate. Unlike previous studies based on the relative difference,\u0000 we have employed cloud data as a whole time-series without detrending. We found that the\u0000 coverage of high-level and low-level cloud is at a maximum when the solar north-south\u0000 asymmetry is close to the minimum, and one or two years after the solar north-south\u0000 asymmetry is at a maximum, respectively. The global surface air temperature is at a\u0000 maximum five years after the solar north-south asymmetry is at a maximum, and the\u0000 optical depth is at a minimum when the solar north-south asymmetry is at a maximum. We\u0000 also found that during the descending period of solar activity, the coverage of\u0000 low-level cloud is at a maximum, and global surface air temperature and cloud optical\u0000 depth are at a minimum, and that the total column water vapor is at a maximum one or two\u0000 years after the solar maximum.","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":"3 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81957213","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Numerical Analysis of Relative Orbit Control Strategy for CANYVAL-X Mission CANYVAL-X任务相对轨道控制策略数值分析

IF 0.5

Journal of Astronomy and Space Sciences Pub Date : 2019-12-01 DOI: 10.5140/JASS.2019.36.4.235

Youngro Lee, Sang-Young Park, Jae-Pil Park, Youngbum Song

{"title":"Numerical Analysis of Relative Orbit Control Strategy for CANYVAL-X Mission","authors":"Youngro Lee, Sang-Young Park, Jae-Pil Park, Youngbum Song","doi":"10.5140/JASS.2019.36.4.235","DOIUrl":"https://doi.org/10.5140/JASS.2019.36.4.235","url":null,"abstract":"This paper suggests a relative orbit control strategy for the CubeSat Astronomy\u0000 by NASA and Yonsei using Virtual Telescope Alignment eXperiment (CANYVAL-X) mission\u0000 whose main goal is to demonstrate an essential technique, which is an arrangement among\u0000 two satellites and a specific celestial object, referred to as inertial alignment, for a\u0000 next-generation virtual space telescope. The inertial alignment system is a relative\u0000 orbit control system and has requirements for the relative state. Through the proposed\u0000 orbit control strategy, consisting of separation, proximity keeping, and\u0000 reconfiguration, the requirements will be satisfied. The separation direction of the two\u0000 CubeSats with respect to the orbital plane is decided to provide advantageous initial\u0000 condition to the orbit controller. Proximity keeping is accomplished by differential\u0000 atmospheric drag control (DADC), which generates acceleration by changing the\u0000 spacecraft’s effective cross section via attitude control rather than consuming\u0000 propellant. Reconfiguration is performed to meet the requirements after proximity\u0000 keeping. Numerical simulations show that the requirements can be satisfied by the\u0000 relative orbit control strategy. Furthermore, through numerical simulations, it is\u0000 demonstrated that the inertial alignment can be achieved. A beacon signal had been\u0000 received for several months after the launch; however, we have lost the signal at\u0000 present.","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":"15 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88635575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Observational Arc-Length Effect on Orbit Determination for Korea Pathfinder Lunar Orbiter in the Earth-Moon Transfer Phase Using a Sequential Estimation 观测弧长效应对韩国探路者月球轨道器地月转移阶段轨道确定的序贯估计

IF 0.5

Journal of Astronomy and Space Sciences Pub Date : 2019-12-01 DOI: 10.5140/JASS.2019.36.4.293

Young-Rok Kim, Young-Joo Song

{"title":"Observational Arc-Length Effect on Orbit Determination for Korea Pathfinder Lunar\u0000 Orbiter in the Earth-Moon Transfer Phase Using a Sequential Estimation","authors":"Young-Rok Kim, Young-Joo Song","doi":"10.5140/JASS.2019.36.4.293","DOIUrl":"https://doi.org/10.5140/JASS.2019.36.4.293","url":null,"abstract":"In this study, the observational arc-length effect on orbit determination (OD)\u0000 for the Korea Pathfinder Lunar Orbiter (KPLO) in the Earth-Moon Transfer phase was\u0000 investigated. For the OD, we employed a sequential estimation using the extended Kalman\u0000 filter and a fixed-point smoother. The mission periods, comprised between the perigee\u0000 maneuvers (PM) and the lunar orbit insertion (LOI) maneuver in a 3.5 phasing loop of the\u0000 KPLO, was the primary target. The total period was divided into three phases:\u0000 launch–PM1, PM1–PM3, and PM3–LOI. The Doppler and range data obtained from three\u0000 tracking stations [included in the deep space network (DSN) and Korea Deep Space Antenna\u0000 (KDSA)] were utilized for the OD. Six arc-length cases (24 hrs, 48 hrs, 60 hrs, 3 days,\u0000 4 days, and 5 days) were considered for the arc-length effect investigation. In order to\u0000 evaluate the OD accuracy, we analyzed the position uncertainties, the precision of orbit\u0000 overlaps, and the position differences between true and estimated trajectories. The\u0000 maximum performance of 3-day OD approach was observed in the case of stable flight\u0000 dynamics operations and robust navigation capability. This study provides a guideline\u0000 for the flight dynamics operations of the KPLO in the trans-lunar phase.","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":"19 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82746727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

Precise Orbit Determination Based on the Unscented Transform for Optical Observations 基于Unscented变换的光学观测精确定轨

IF 0.5

Journal of Astronomy and Space Sciences Pub Date : 2019-12-01 DOI: 10.5140/jass.2019.36.4.249

Hyewon Hwang, Eunji Lee, Sang-Young Park

{"title":"Precise Orbit Determination Based on the Unscented Transform for Optical\u0000 Observations","authors":"Hyewon Hwang, Eunji Lee, Sang-Young Park","doi":"10.5140/jass.2019.36.4.249","DOIUrl":"https://doi.org/10.5140/jass.2019.36.4.249","url":null,"abstract":"In this study, the precise orbit determination (POD) software is developed for\u0000 optical observation. To improve the performance of the estimation algorithm, a nonlinear\u0000 batch filter, based on the unscented transform (UT) that overcomes the disadvantages of\u0000 the least-squares (LS) batch filter, is utilized. The LS and UT batch filter algorithms\u0000 are verified through numerical simulation analysis using artificial optical\u0000 measurements. We use the real optical observation data of a low Earth orbit (LEO)\u0000 satellite, Cryosat-2, observed from optical wide-field patrol network (OWL-Net), to\u0000 verify the performance of the POD software developed. The effects of light travel time,\u0000 annual aberration, and diurnal aberration are considered as error models to correct\u0000 OWL-Net data. As a result of POD, measurement residual and estimated state vector of the\u0000 LS batch filter converge to the local minimum when the initial orbit error is large or\u0000 the initial covariance matrix is smaller than the initial error level. However, UT batch\u0000 filter converges to the global minimum, irrespective of the initial orbit error and the\u0000 initial covariance matrix.","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":"196 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85310468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

UY Ursae Majoris: An A-Subtype W UMa System with a Very Large Fill-Out Factor and an Extreme Mass Ratio UY大熊:具有非常大填充系数和极端质量比的a -亚型wuma系统

IF 0.5

Journal of Astronomy and Space Sciences Pub Date : 2019-12-01 DOI: 10.5140/JASS.2019.36.4.265

Chun-Hwey Kim, Mi-Hwa Song, Jang-Ho Park, M. Jeong, Hye-Young Kim, C. Han

{"title":"UY Ursae Majoris: An A-Subtype W UMa System with a Very Large Fill-Out Factor and\u0000 an Extreme Mass Ratio","authors":"Chun-Hwey Kim, Mi-Hwa Song, Jang-Ho Park, M. Jeong, Hye-Young Kim, C. Han","doi":"10.5140/JASS.2019.36.4.265","DOIUrl":"https://doi.org/10.5140/JASS.2019.36.4.265","url":null,"abstract":"We present new BVRI light curves of UY UMa with no O’Connell effect and a flat\u0000 bottom secondary eclipse. Light curve synthesis with the Wilson-Devinney code gives a\u0000 new solution, which is quite different from the previous study: UY UMa is an A-subtype\u0000 over-contact binary with a small mass ratio of q = 0.21, a high inclination of 81°.4, a\u0000 small temperature difference of ΔT = 18°, a large fill-out factor of f = 0.61, and a\u0000 third light of approximately 10% of the total systemic light. The absolute dimensions\u0000 were newly determined. Seventeen new times of minimum light have been calculated from\u0000 our observations. The period study indicates that the orbital period has intricately\u0000 varied in a secular period increase in which two cyclical terms with periods of 12y.0\u0000 and 46y.3 are superposed. The secular period increase was interpreted to be due to a\u0000 conservative mass transfer of 2.68 × 10–8 M⊙/yr from the less massive to the more\u0000 massive star. The cyclical components are discussed in terms of double-light time\u0000 contributions from two additional bound stars. The statistical relations of Yang &\u0000 Qian (2015) among the physical parameters of 45 deep, low mass ratio contact binaries\u0000 were revisited by using the physical parameters of UY UMa and 25 Kepler contact binaries\u0000 provided by Şenavci et al. (2016).","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":"6 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75548331","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Association between Solar Variability and Teleconnection Index 太阳变率与遥相关指数的关系

IF 0.5

Journal of Astronomy and Space Sciences Pub Date : 2019-09-01 DOI: 10.5140/JASS.2019.36.3.149

Jung-Hee Kim, Heon-Young Chang

{"title":"Association between Solar Variability and Teleconnection Index","authors":"Jung-Hee Kim, Heon-Young Chang","doi":"10.5140/JASS.2019.36.3.149","DOIUrl":"https://doi.org/10.5140/JASS.2019.36.3.149","url":null,"abstract":"In this study, we investigate the associations between the solar variability and\u0000 teleconnection indices, which influence atmospheric circulation and subsequently, the\u0000 spatial distribution of the global pressure system. A study of the link between the Sun\u0000 and a large-scale mode of climate variability, which may indirectly affect the Earth’s\u0000 climate and weather, is crucial because the feedbacks of solar variability to an\u0000 autogenic or internal process should be considered with due care. We have calculated the\u0000 normalized cross-correlations of the total sunspot area, the total sunspot number, and\u0000 the solar North–South asymmetry with teleconnection indices. We have found that the\u0000 Southern Oscillation Index (SOI) index is anti-correlated with both solar activity and\u0000 the solar North–South asymmetry, with a ∼3-year lag. This finding not only agrees with\u0000 the fact that El Niño episodes are likely to occur around the solar maximum, but also\u0000 explains why tropical cyclones occurring in the solar maximum periods and in El Niño\u0000 periods appear similar. Conversely, other teleconnection indices, such as the Arctic\u0000 Oscillation (AO) index, the Antarctic Oscillation (AAO) index, and the Paciﬁc-North\u0000 American (PNA) index, are weakly or only slightly correlated with solar activity, which\u0000 emphasizes that response of terrestrial climate and weather to solar variability are\u0000 local in space. It is also found that correlations between teleconnection indices and\u0000 solar activity are as good as correlations resulting from the teleconnection indices\u0000 themselves.","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":"34 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84488349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Analysis of Magnetic Dipole Moment for a 300-W Solar-Cell Array 300w太阳能电池阵列磁偶极矩分析

IF 0.5

Journal of Astronomy and Space Sciences Pub Date : 2019-09-01 DOI: 10.5140/jass.2019.36.3.181

G. Shin, Dong-Guk Kim, Se-Jin Kwon, Hu-Seung Lee

{"title":"Analysis of Magnetic Dipole Moment for a 300-W Solar-Cell Array","authors":"G. Shin, Dong-Guk Kim, Se-Jin Kwon, Hu-Seung Lee","doi":"10.5140/jass.2019.36.3.181","DOIUrl":"https://doi.org/10.5140/jass.2019.36.3.181","url":null,"abstract":"The attitude information of spacecraft can be obtained by the sensors attached to\u0000 it using a star tracker, three-axis magnetometer, three-axis gyroscope, and a global\u0000 positioning signal receiver. By using these sensors, the spacecraft can be maneuvered by\u0000 actuators that generate torques. In particular, electromagnetic-torque bars can be used\u0000 for attitude control and as a momentum-canceling instrument. The spacecraft momentum can\u0000 be created by the current through the electrical circuits and coils. Thus, the current\u0000 around the electromagnetic-torque bars is a critical factor for precisely controlling\u0000 the spacecraft. In connection with these concerns, a solar-cell array can be considered\u0000 to prevent generation of a magnetic dipole moment because the solar-cell array can\u0000 introduce a large amount of current through the electrical wires. The maximum value of a\u0000 magnetic dipole moment that cannot affect precise control is 0.25 A·m2, which takes into\u0000 account the current that flows through the reaction-wheel assembly and the\u0000 magnetic-torque current. In this study, we designed a 300-W solar cell array and\u0000 presented an optimal wire-routing method to minimize the magnetic dipole moment for\u0000 space applications. We verified our proposed method by simulation.","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":"21 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79050324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The Barium Star HD204075: Iron Abundance and the Absence of Evidence for Accretion 钡星HD204075:铁丰度和吸积证据的缺失

IF 0.5

Journal of Astronomy and Space Sciences Pub Date : 2019-09-01 DOI: 10.5140/JASS.2019.36.3.105

Yeuncheol Jeong, A. Yushchenko, V. Gopka, V. Yushchenko, P. Rittipruk, K. S. Jeong, A. Demessinova

{"title":"The Barium Star HD204075: Iron Abundance and the Absence of Evidence for\u0000 Accretion","authors":"Yeuncheol Jeong, A. Yushchenko, V. Gopka, V. Yushchenko, P. Rittipruk, K. S. Jeong, A. Demessinova","doi":"10.5140/JASS.2019.36.3.105","DOIUrl":"https://doi.org/10.5140/JASS.2019.36.3.105","url":null,"abstract":"Spectroscopic observations of barium star ζ Capricornus (HD204075) obtained at\u0000 the 8.2 m telescope of the European Southern Observatory, with a spectral resolving\u0000 power R = 80,000 and signal to noise ratio greater than 300, were used to refine the\u0000 atmospheric parameters. We found new values for effective temperature (Teff = 5,300 ± 50\u0000 K), surface gravity (log g = 1.82 ± 0.15), micro-turbulent velocity (vmicro = 2.52 ±\u0000 0.10 km/s), and iron abundance (log N (Fe) = 7.32 ± 0.06). Previously published\u0000 abundances of chemical elements in the atmosphere of HD204075 were analyzed and no\u0000 correlations of these abundances with the second ionization potentials of these elements\u0000 were found. This excludes the possible influence of accretion of hydrogen and helium\u0000 atoms from the interstellar or circumstellar environment to the atmosphere of this star.\u0000 The accretion of nuclear processed matter from the evolved binary companion was primary\u0000 cause of the abundance anomalies. The young age of HD204075 allows an estimation of the\u0000 time-scale for the creation of the abundance anomalies arising from accretion of\u0000 interstellar hydrogen and helium as is the case of stars with low magnetic fields; which\u0000 we estimate should exceed 108 years.","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":"4 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80673702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0