Pub Date : 2021-09-01DOI: 10.5140/jass.2021.38.3.175
A. Yushchenko, Seunghyun Kim, Yeuncheol Jeong, A. Demessinova, V. Yushchenko, D. Doikov, V. Gopka, K. S. Jeong, P. Rittipruk
The dependencies of the chemical element abundances in stellar atmospheres with respect to solar abundances on the second ionization potentials of the same elements were investigated using the published stellar abundance patterns for 1,149 G and K giants in the Local Region of the Galaxy. The correlations between the relative abundances of chemical elements and their second ionization potentials were calculated for groups of stars with effective temperatures between 3,764 and 7,725 K. Correlations were identified for chemical elements with second ionization potentials of 12.5 eV to 20 eV and for elements with second ionization potentials higher than 20 eV. For the first group of elements, the correlation coefficients were positive for stars with effective temperatures lower than 5,300 K and negative for stars with effective temperatures from 5,300 K to 7,725 K. The results of this study and the comparison with earlier results for hotter stars confirm the variations in these correlations with the effective temperature. A possible explanation for the observed effects is the accretion of hydrogen and helium atoms from the interstellar medium.
{"title":"The Possible Signs of Hydrogen and Helium Accretion from Interstellar Medium on the\u0000 Atmospheres of F-K Giants in the Local Region of the Galaxy","authors":"A. Yushchenko, Seunghyun Kim, Yeuncheol Jeong, A. Demessinova, V. Yushchenko, D. Doikov, V. Gopka, K. S. Jeong, P. Rittipruk","doi":"10.5140/jass.2021.38.3.175","DOIUrl":"https://doi.org/10.5140/jass.2021.38.3.175","url":null,"abstract":"The dependencies of the chemical element abundances in stellar atmospheres with\u0000 respect to solar abundances on the second ionization potentials of the same elements\u0000 were investigated using the published stellar abundance patterns for 1,149 G and K\u0000 giants in the Local Region of the Galaxy. The correlations between the relative\u0000 abundances of chemical elements and their second ionization potentials were calculated\u0000 for groups of stars with effective temperatures between 3,764 and 7,725 K. Correlations\u0000 were identified for chemical elements with second ionization potentials of 12.5 eV to 20\u0000 eV and for elements with second ionization potentials higher than 20 eV. For the first\u0000 group of elements, the correlation coefficients were positive for stars with effective\u0000 temperatures lower than 5,300 K and negative for stars with effective temperatures from\u0000 5,300 K to 7,725 K. The results of this study and the comparison with earlier results\u0000 for hotter stars confirm the variations in these correlations with the effective\u0000 temperature. A possible explanation for the observed effects is the accretion of\u0000 hydrogen and helium atoms from the interstellar medium.","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":"80 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2021-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84235537","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}
Pub Date : 2021-08-15DOI: 10.5140/JASS.2021.38.3.157
Hosub Song, Jaeheung Park, Jaejin Lee
We describe a method for the in-orbit calibration of body-mounted magnetometers based on the CHAOS-7 geomagnetic field model. The code is designed to find the true calibration parameters autonomously by using only the onboard magnetometer data and the corresponding CHAOS outputs. As the model output and satellite data have different coordinate systems, they are first transformed to a Star Tracker Coordinate (STC). Then, non-linear optimization processes are run to minimize the differences between the CHAOS-7 model and satellite data in the STC. The process finally searches out a suite of calibration parameters that can maximize the model-data agreement. These parameters include the instrument gain, offset, axis orthogonality, and Euler rotation matrices between the magnetometer frame and the STC. To validate the performance of the Python code, we first produce pseudo satellite data by convoluting CHAOS-7 model outputs with a prescribed set of the ‘true’ calibration parameters. Then, we let the code autonomously undistort the pseudo satellite data through optimization processes, which ultimately track down the initially prescribed calibration parameters. The reconstructed parameters are in good agreement with the prescribed (true) ones, which demonstrates that the code can be used for actual instrument data calibration. This study is performed using Python 3.8.5, NumPy 1.19.2, SciPy 1.6, AstroPy 4.2, SpacePy 0.2.1, and ChaosmagPy 0.5 including the CHAOS-7.6 geomagnetic field model. This code will be utilized for processing NextSat-1 and Small scale magNetospheric and Ionospheric Plasma Experiment (SNIPE) data in the future.
{"title":"Magnetometer Calibration Based on the CHAOS-7 Model","authors":"Hosub Song, Jaeheung Park, Jaejin Lee","doi":"10.5140/JASS.2021.38.3.157","DOIUrl":"https://doi.org/10.5140/JASS.2021.38.3.157","url":null,"abstract":"We describe a method for the in-orbit calibration of body-mounted magnetometers\u0000 based on the CHAOS-7 geomagnetic field model. The code is designed to find the true\u0000 calibration parameters autonomously by using only the onboard magnetometer data and the\u0000 corresponding CHAOS outputs. As the model output and satellite data have different\u0000 coordinate systems, they are first transformed to a Star Tracker Coordinate (STC). Then,\u0000 non-linear optimization processes are run to minimize the differences between the\u0000 CHAOS-7 model and satellite data in the STC. The process finally searches out a suite of\u0000 calibration parameters that can maximize the model-data agreement. These parameters\u0000 include the instrument gain, offset, axis orthogonality, and Euler rotation matrices\u0000 between the magnetometer frame and the STC. To validate the performance of the Python\u0000 code, we first produce pseudo satellite data by convoluting CHAOS-7 model outputs with a\u0000 prescribed set of the ‘true’ calibration parameters. Then, we let the code autonomously\u0000 undistort the pseudo satellite data through optimization processes, which ultimately\u0000 track down the initially prescribed calibration parameters. The reconstructed parameters\u0000 are in good agreement with the prescribed (true) ones, which demonstrates that the code\u0000 can be used for actual instrument data calibration. This study is performed using Python\u0000 3.8.5, NumPy 1.19.2, SciPy 1.6, AstroPy 4.2, SpacePy 0.2.1, and ChaosmagPy 0.5 including\u0000 the CHAOS-7.6 geomagnetic field model. This code will be utilized for processing\u0000 NextSat-1 and Small scale magNetospheric and Ionospheric Plasma Experiment (SNIPE) data\u0000 in the future.","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":"5 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2021-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73662483","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}
Pub Date : 2021-06-01DOI: 10.5140/JASS.2021.38.2.135
Tae-Yong Yang, Y. Kwak, Jaewook Lee, Jaeheung Park, Seonghwan Choi
We report, for the first time, the afternoon (i.e., from noon to sunset time) observations of the northern mid-latitude E-region field-aligned irregularities (FAIs) made by the very high frequency (VHF) coherent backscatter radar operated continuously since 29 December 2009 at Daejeon (36.18°N, 127.14°E, 26.7°N dip latitude) in South Korea. We present the statistical characteristics of the mid-latitude afternoon E-region FAIs based on the continuous radar observations. Echo signal-to-noise ratio (SNR) of the afternoon E-region FAIs is found to be as high as 35 dB, mostly occurring around 100–135 km altitudes. Most spectral widths of the afternoon echoes are close to zero, indicating that the irregularities during the afternoon time are not related to turbulent plasma motions. The occurrence of afternoon E-regional FAI is observed with significant seasonal variation, with a maximum in summer and a minimum in winter. Furthermore, to investigate the afternoon E-region FAIs- Sporadic E (Es) relationship, the FAIs have also been compared with Es parameters based on observations made from an ionosonde located at Icheon (37.14°N, 127.54°E, 27.7°N dip latitude), which is 100 km north of Daejeon. The virtual height of Es (h’Es) is mainly in the height range of 105 km to 110 km, which is 5 km to 10 km greater than the bottom of the FAI. There is no relationship between the FAI SNR and the highest frequencies (ftEs) (or blanket frequencies (fbEs)). SNR of FAIs, however, is found to be related well with (ftEs–fbEs).
{"title":"The First Report on the Afternoon E -Region Plasma Density Irregularities in Middle\u0000 Latitude","authors":"Tae-Yong Yang, Y. Kwak, Jaewook Lee, Jaeheung Park, Seonghwan Choi","doi":"10.5140/JASS.2021.38.2.135","DOIUrl":"https://doi.org/10.5140/JASS.2021.38.2.135","url":null,"abstract":"We report, for the first time, the afternoon (i.e., from noon to sunset time)\u0000 observations of the northern mid-latitude E-region field-aligned irregularities (FAIs)\u0000 made by the very high frequency (VHF) coherent backscatter radar operated continuously\u0000 since 29 December 2009 at Daejeon (36.18°N, 127.14°E, 26.7°N dip latitude) in South\u0000 Korea. We present the statistical characteristics of the mid-latitude afternoon E-region\u0000 FAIs based on the continuous radar observations. Echo signal-to-noise ratio (SNR) of the\u0000 afternoon E-region FAIs is found to be as high as 35 dB, mostly occurring around 100–135\u0000 km altitudes. Most spectral widths of the afternoon echoes are close to zero, indicating\u0000 that the irregularities during the afternoon time are not related to turbulent plasma\u0000 motions. The occurrence of afternoon E-regional FAI is observed with significant\u0000 seasonal variation, with a maximum in summer and a minimum in winter. Furthermore, to\u0000 investigate the afternoon E-region FAIs- Sporadic E (Es) relationship, the FAIs have\u0000 also been compared with Es parameters based on observations made from an ionosonde\u0000 located at Icheon (37.14°N, 127.54°E, 27.7°N dip latitude), which is 100 km north of\u0000 Daejeon. The virtual height of Es (h’Es) is mainly in the height range of 105 km to 110\u0000 km, which is 5 km to 10 km greater than the bottom of the FAI. There is no relationship\u0000 between the FAI SNR and the highest frequencies (ftEs) (or blanket frequencies (fbEs)).\u0000 SNR of FAIs, however, is found to be related well with (ftEs–fbEs).","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":"27 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77713045","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}
Pub Date : 2021-06-01DOI: 10.5140/JASS.2021.38.2.93
E. H. Khattab, F. A. Abd El-Salam, W. A. Rahoma
In this work, the problem of resonance caused by some gravitational potentials due to Mercury and a third body, namely the Sun, together with some non-gravitational perturbations, specifically coronal mass ejections and solar wind in addition to radiation pressure, are investigated. Some simplifying assumptions without loss of accuracy are employed. The considered force model is constructed. Then the Delaunay canonical set is introduced. The Hamiltonian of the problem is obtained then it is expressed in terms of the Deluanay canonical set. The Hamiltonian is re-ordered to adopt it to the perturbation technique used to solve the problem. The Lie transform method is surveyed. The Hamiltonian is doubly averaged. The resonance capture is investigated. Finally, some numerical simulations are illustrated and are analyzed. Many resonant inclinations are revealed.
{"title":"Resonance Capture for a Mercurian Orbiter in the Vicinity of Sun","authors":"E. H. Khattab, F. A. Abd El-Salam, W. A. Rahoma","doi":"10.5140/JASS.2021.38.2.93","DOIUrl":"https://doi.org/10.5140/JASS.2021.38.2.93","url":null,"abstract":"In this work, the problem of resonance caused by some gravitational potentials\u0000 due to Mercury and a third body, namely the Sun, together with some non-gravitational\u0000 perturbations, specifically coronal mass ejections and solar wind in addition to\u0000 radiation pressure, are investigated. Some simplifying assumptions without loss of\u0000 accuracy are employed. The considered force model is constructed. Then the Delaunay\u0000 canonical set is introduced. The Hamiltonian of the problem is obtained then it is\u0000 expressed in terms of the Deluanay canonical set. The Hamiltonian is re-ordered to adopt\u0000 it to the perturbation technique used to solve the problem. The Lie transform method is\u0000 surveyed. The Hamiltonian is doubly averaged. The resonance capture is investigated.\u0000 Finally, some numerical simulations are illustrated and are analyzed. Many resonant\u0000 inclinations are revealed.","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":"61 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83998433","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}
Pub Date : 2021-06-01DOI: 10.5140/JASS.2021.38.2.83
J. Chae
The ionization degree of hydrogen is crucial in the physics of the plasma in the solar chromosphere. It specifically limits the range of plasma temperatures that can be determined from the Hα line. Given that the chromosphere greatly deviates from the local thermodynamic equilibrium (LTE) condition, precise determinations of hydrogen ionization require the solving of the full set of non-LTE radiative transfer equations throughout the atmosphere, which is usually a formidable task. In many cases, it is still necessary to obtain a quick estimate of hydrogen ionization without having to solve for the non-LTE radiative transfer. Here, we present a simple method to meet this need. We adopt the assumption that the photoionizing radiation field changes little over time, even if physical conditions change locally. With this assumption, the photoionization rate can be obtained from a published atmosphere model and can be used to determine the degree of hydrogen ionization when the temperature and electron density are specified. The application of our method indicates that in the chromospheric environment, plasma features contain more than 10% neutral hydrogen at temperatures lower than 17,000 K but less than 1% neutral hydrogen at temperatures higher than 23,000 K, implying that the hydrogen temperature determined from the Hα line is physically plausible if it is lower than 20,000 K, but may not be real, if it is higher than 25,000 K. We conclude that our method can be readily exploited to obtain a quick estimate of hydrogen ionization in plasma features in the solar chromosphere.
{"title":"Ionization of Hydrogen in the Solar Atmosphere","authors":"J. Chae","doi":"10.5140/JASS.2021.38.2.83","DOIUrl":"https://doi.org/10.5140/JASS.2021.38.2.83","url":null,"abstract":"The ionization degree of hydrogen is crucial in the physics of the plasma in the\u0000 solar chromosphere. It specifically limits the range of plasma temperatures that can be\u0000 determined from the Hα line. Given that the chromosphere greatly deviates from the local\u0000 thermodynamic equilibrium (LTE) condition, precise determinations of hydrogen ionization\u0000 require the solving of the full set of non-LTE radiative transfer equations throughout\u0000 the atmosphere, which is usually a formidable task. In many cases, it is still necessary\u0000 to obtain a quick estimate of hydrogen ionization without having to solve for the\u0000 non-LTE radiative transfer. Here, we present a simple method to meet this need. We adopt\u0000 the assumption that the photoionizing radiation field changes little over time, even if\u0000 physical conditions change locally. With this assumption, the photoionization rate can\u0000 be obtained from a published atmosphere model and can be used to determine the degree of\u0000 hydrogen ionization when the temperature and electron density are specified. The\u0000 application of our method indicates that in the chromospheric environment, plasma\u0000 features contain more than 10% neutral hydrogen at temperatures lower than 17,000 K but\u0000 less than 1% neutral hydrogen at temperatures higher than 23,000 K, implying that the\u0000 hydrogen temperature determined from the Hα line is physically plausible if it is lower\u0000 than 20,000 K, but may not be real, if it is higher than 25,000 K. We conclude that our\u0000 method can be readily exploited to obtain a quick estimate of hydrogen ionization in\u0000 plasma features in the solar chromosphere.","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":"27 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78272510","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}
Pub Date : 2021-06-01DOI: 10.5140/JASS.2021.38.2.145
Young-Joo Song, Donghun Lee
In this work, preliminary launch opportunities from NARO Space Center to the Sun-Earth Lagrange point are analyzed. Among five different Sun-Earth Lagrange points, L1 and L2 points are selected as suitable candidates for, respectively, solar and astrophysics missions. With high fidelity dynamics models, the L1 and L2 point targeting problem is formulated regarding the location of NARO Space Center and relevant Target Interface Point (TIP) for each different launch date is derived including launch injection energy per unit mass (C3), Right ascension of the injection orbit Apoapsis Vector (RAV) and Declination of the injection orbit Apoapsis Vector (DAV). Potential launch periods to achieve L1 and L2 transfer trajectory are also investigated regarding coasting characteristics from NARO Space Center. The magnitude of the Lagrange Orbit Insertion (LOI) burn, as well as the Orbit Maintenance (OM) maneuver to maintain more than one year of mission orbit around the Lagrange points, is also derived as an example. Even the current work has been made under many assumptions as there are no specific mission goals currently defined yet, so results from the current work could be a good starting point to extend diversities of future Korean deep-space missions.
{"title":"Preliminary Analysis on Launch Opportunities for Sun-Earth Lagrange Points Mission\u0000 from NARO Space Center","authors":"Young-Joo Song, Donghun Lee","doi":"10.5140/JASS.2021.38.2.145","DOIUrl":"https://doi.org/10.5140/JASS.2021.38.2.145","url":null,"abstract":"In this work, preliminary launch opportunities from NARO Space Center to the\u0000 Sun-Earth Lagrange point are analyzed. Among five different Sun-Earth Lagrange points,\u0000 L1 and L2 points are selected as suitable candidates for, respectively, solar and\u0000 astrophysics missions. With high fidelity dynamics models, the L1 and L2 point targeting\u0000 problem is formulated regarding the location of NARO Space Center and relevant Target\u0000 Interface Point (TIP) for each different launch date is derived including launch\u0000 injection energy per unit mass (C3), Right ascension of the injection orbit Apoapsis\u0000 Vector (RAV) and Declination of the injection orbit Apoapsis Vector (DAV). Potential\u0000 launch periods to achieve L1 and L2 transfer trajectory are also investigated regarding\u0000 coasting characteristics from NARO Space Center. The magnitude of the Lagrange Orbit\u0000 Insertion (LOI) burn, as well as the Orbit Maintenance (OM) maneuver to maintain more\u0000 than one year of mission orbit around the Lagrange points, is also derived as an\u0000 example. Even the current work has been made under many assumptions as there are no\u0000 specific mission goals currently defined yet, so results from the current work could be\u0000 a good starting point to extend diversities of future Korean deep-space missions.\u0000","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":"504 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77457000","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}
Pub Date : 2021-06-01DOI: 10.5140/JASS.2021.38.2.105
Pureum Kim, S. Park, Sungki Cho, J. Jo
In this study, a preliminary trajectory design is conducted for a conceptual spacecraft mission to a near-Earth asteroid (NEA) (99942) Apophis, which is expected to pass by Earth merely 32,000 km from the Earth’s surface in 2029. This close approach event will provide us with a unique opportunity to study changes induced in asteroids during close approaches to massive bodies, as well as the general properties of NEAs. The conceptual mission is set to arrive at and rendezvous with Apophis in 2028 for an advanced study of the asteroid, and some near-optimal (in terms of fuel consumption) trajectories under this mission architecture are to be investigated using a global optimization algorithm called monotonic basin hopping. It is shown that trajectories with a single swing-by from Venus or Earth, or even simpler ones without gravity assist, are the most feasible. In addition, launch opportunities in 2029 yield another possible strategy of leaving Earth around the 2029 close approach event and simply following the asteroid thereafter, which may be an alternative fuel-efficient option that can be adopted if advanced studies of Apophis are not required.
{"title":"A Preliminary Impulsive Trajectory Design for (99942) Apophis Rendezvous\u0000 Mission","authors":"Pureum Kim, S. Park, Sungki Cho, J. Jo","doi":"10.5140/JASS.2021.38.2.105","DOIUrl":"https://doi.org/10.5140/JASS.2021.38.2.105","url":null,"abstract":"In this study, a preliminary trajectory design is conducted for a conceptual\u0000 spacecraft mission to a near-Earth asteroid (NEA) (99942) Apophis, which is expected to\u0000 pass by Earth merely 32,000 km from the Earth’s surface in 2029. This close approach\u0000 event will provide us with a unique opportunity to study changes induced in asteroids\u0000 during close approaches to massive bodies, as well as the general properties of NEAs.\u0000 The conceptual mission is set to arrive at and rendezvous with Apophis in 2028 for an\u0000 advanced study of the asteroid, and some near-optimal (in terms of fuel consumption)\u0000 trajectories under this mission architecture are to be investigated using a global\u0000 optimization algorithm called monotonic basin hopping. It is shown that trajectories\u0000 with a single swing-by from Venus or Earth, or even simpler ones without gravity assist,\u0000 are the most feasible. In addition, launch opportunities in 2029 yield another possible\u0000 strategy of leaving Earth around the 2029 close approach event and simply following the\u0000 asteroid thereafter, which may be an alternative fuel-efficient option that can be\u0000 adopted if advanced studies of Apophis are not required.","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":"19 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79119973","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}
Pub Date : 2021-06-01DOI: 10.5140/JASS.2021.38.2.119
Daniela Espitia, E. Quintero, M. A. Parra
The data set collected during the night of the discovery of a minor body constitutes a too-short arc (TSA), resulting in failure of the differential correction procedure. This makes it necessary to recover the object during subsequent nights to gather more observations that will allow a preliminary orbit to be calculated. In this work, we present a recovery technique based on sampling the admissible region (AdRe) by the constrained Delaunay triangulation. We construct the AdRe in its topocentric and geocentric variants, using logarithmic and exponential metrics, for the following near-Earth-asteroids: (3122) Florence, (3200) Phaethon, 2003 GW, (1864) Daedalus, 2003 BH84 and 1977 QQ5; and the main-belt asteroids: (1738) Oosterhoff, (4690) Strasbourg, (555) Norma, 2006 SO375, 2003 GE55 and (32811) Apisaon. Using our sampling technique, we established the ephemeris region for these objects, using intervals of observation from 25 minutes up to 2 hours, with propagation times from 1 up to 47 days. All these objects were recoverable in a field of vision of 95’ × 72’, except for (3122) Florence and (3200) Phaethon, since they were observed during their closest approach to the Earth. In the case of 2006 SO375, we performed an additional test with only two observations separated by 2 minutes, achieving a recovery of up to 28 days after its discovery, which demonstrates the potential of our technique.
{"title":"Recovery of Asteroids from Observations of Too-Short Arcs by Triangulating Their\u0000 Admissible Regions","authors":"Daniela Espitia, E. Quintero, M. A. Parra","doi":"10.5140/JASS.2021.38.2.119","DOIUrl":"https://doi.org/10.5140/JASS.2021.38.2.119","url":null,"abstract":"The data set collected during the night of the discovery of a minor body\u0000 constitutes a too-short arc (TSA), resulting in failure of the differential correction\u0000 procedure. This makes it necessary to recover the object during subsequent nights to\u0000 gather more observations that will allow a preliminary orbit to be calculated. In this\u0000 work, we present a recovery technique based on sampling the admissible region (AdRe) by\u0000 the constrained Delaunay triangulation. We construct the AdRe in its topocentric and\u0000 geocentric variants, using logarithmic and exponential metrics, for the following\u0000 near-Earth-asteroids: (3122) Florence, (3200) Phaethon, 2003 GW, (1864) Daedalus, 2003\u0000 BH84 and 1977 QQ5; and the main-belt asteroids: (1738) Oosterhoff, (4690) Strasbourg,\u0000 (555) Norma, 2006 SO375, 2003 GE55 and (32811) Apisaon. Using our sampling technique, we\u0000 established the ephemeris region for these objects, using intervals of observation from\u0000 25 minutes up to 2 hours, with propagation times from 1 up to 47 days. All these objects\u0000 were recoverable in a field of vision of 95’ × 72’, except for (3122) Florence and\u0000 (3200) Phaethon, since they were observed during their closest approach to the Earth. In\u0000 the case of 2006 SO375, we performed an additional test with only two observations\u0000 separated by 2 minutes, achieving a recovery of up to 28 days after its discovery, which\u0000 demonstrates the potential of our technique.","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":"1 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84412393","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}
Pub Date : 2021-03-01DOI: 10.5140/JASS.2021.38.1.23
Heon-Young Chang
Utilizing a new version of the sunspot number and group sunspot number dataset available since 2015, we have statistically studied the relationship between solar activity parameters describing solar cycles and the slope of the linear relationship between the monthly sunspot numbers and the monthly number of active days in percentage (AD). As an effort of evaluating possibilities in use of the number of active days to predict solar activity, it is worthwhile to revisit and extend the analysis performed earlier. In calculating the Pearson’s linear correlation coefficient r, the Spearman’s rank-order correlation coefficient rs, and the Kendall’s τ coefficient with the rejection probability, we have calculated the slope for a given solar cycle in three different ways, namely, by counting the spotless day that occurred during the ascending phase and the descending phase of the solar cycle separately, and during the period corresponding to solar minimum ± 2 years as well. We have found that the maximum solar sunspot number of a given solar cycle and the duration of the ascending phase are hardly correlated with the slope of a linear function of the monthly sunspot numbers and AD. On the other hand, the duration of a solar cycle is found to be marginally correlated with the slope with the rejection probabilities less than a couple of percent. We have also attempted to compare the relation of the monthly sunspot numbers with AD for the even and odd solar cycles. It is inconclusive, however, that the slopes of the linear relationship between the monthly group numbers and AD are subject to the even and odd solar cycles.
{"title":"Active Days around Solar Minimum and Solar Cycle Parameter","authors":"Heon-Young Chang","doi":"10.5140/JASS.2021.38.1.23","DOIUrl":"https://doi.org/10.5140/JASS.2021.38.1.23","url":null,"abstract":"Utilizing a new version of the sunspot number and group sunspot number dataset\u0000 available since 2015, we have statistically studied the relationship between solar\u0000 activity parameters describing solar cycles and the slope of the linear relationship\u0000 between the monthly sunspot numbers and the monthly number of active days in percentage\u0000 (AD). As an effort of evaluating possibilities in use of the number of active days to\u0000 predict solar activity, it is worthwhile to revisit and extend the analysis performed\u0000 earlier. In calculating the Pearson’s linear correlation coefficient r, the Spearman’s\u0000 rank-order correlation coefficient rs, and the Kendall’s τ coefficient with the\u0000 rejection probability, we have calculated the slope for a given solar cycle in three\u0000 different ways, namely, by counting the spotless day that occurred during the ascending\u0000 phase and the descending phase of the solar cycle separately, and during the period\u0000 corresponding to solar minimum ± 2 years as well. We have found that the maximum solar\u0000 sunspot number of a given solar cycle and the duration of the ascending phase are hardly\u0000 correlated with the slope of a linear function of the monthly sunspot numbers and AD. On\u0000 the other hand, the duration of a solar cycle is found to be marginally correlated with\u0000 the slope with the rejection probabilities less than a couple of percent. We have also\u0000 attempted to compare the relation of the monthly sunspot numbers with AD for the even\u0000 and odd solar cycles. It is inconclusive, however, that the slopes of the linear\u0000 relationship between the monthly group numbers and AD are subject to the even and odd\u0000 solar cycles.","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":"33 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82784422","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}
Pub Date : 2021-03-01DOI: 10.5140/JASS.2021.38.1.1
Luis E. Salazar-Manzano, E. Quintero
The observation of stellar occultations constitutes one of the most important techniques for determining the dimensions and establishing the physical parameters of small Solar System bodies. The most substantial calculations are obtained from multiple observations of the same event, which turns the observation of stellar occultations into highly collaborative work and groups teams of observers through international networks. The above situation also requires the participation of both professional and amateur observers in these collaborative networks. With the aim of promoting the participation of professional and amateur groups in the collaborative observation of stellar occultations, we present the methodology developed by the Astronomical Observatory of the Technological University of Pereira (OAUTP) for the observations of occultations due small Solar System bodies. We expose the three fundamental phases of the process: the plan to make observations, the capture of the events, and the treatment of the data. We apply our methodology using a fixed station and a mobile station to observe stellar occultations due to MBAs (354) Eleonora (61) Danae (15112) Arlenewolfe (3915) Fukushima (61788) 2000 QP181 (425) Cornelia (257) Silesia (386) Siegena and (41) Daphne, and due to TNOs 1998BU48 and (529823) 2010 PP81. The positive detections for the objects (257) Silesia (386) Siegena and (41) Daphne allow us to derive lower limits in the diameter of the MBAs of 63.1 km, 166.2 km and 158.7 km and offsets in the astrometric position (Δαc cosδc, Δδc) of 622.30 ± 0.83, 15.23 ± 9.88 mas, 586.06 ± 1.68, 43.03 ± 13.88 mas and –413.44 ± 9.42, 234.05 ± 19.12 mas, respectively.
{"title":"Methodology for the Observations of Stellar Occultations by Small Bodies of the\u0000 Solar System","authors":"Luis E. Salazar-Manzano, E. Quintero","doi":"10.5140/JASS.2021.38.1.1","DOIUrl":"https://doi.org/10.5140/JASS.2021.38.1.1","url":null,"abstract":"The observation of stellar occultations constitutes one of the most important\u0000 techniques for determining the dimensions and establishing the physical parameters of\u0000 small Solar System bodies. The most substantial calculations are obtained from multiple\u0000 observations of the same event, which turns the observation of stellar occultations into\u0000 highly collaborative work and groups teams of observers through international networks.\u0000 The above situation also requires the participation of both professional and amateur\u0000 observers in these collaborative networks. With the aim of promoting the participation\u0000 of professional and amateur groups in the collaborative observation of stellar\u0000 occultations, we present the methodology developed by the Astronomical Observatory of\u0000 the Technological University of Pereira (OAUTP) for the observations of occultations due\u0000 small Solar System bodies. We expose the three fundamental phases of the process: the\u0000 plan to make observations, the capture of the events, and the treatment of the data. We\u0000 apply our methodology using a fixed station and a mobile station to observe stellar\u0000 occultations due to MBAs (354) Eleonora (61) Danae (15112) Arlenewolfe (3915) Fukushima\u0000 (61788) 2000 QP181 (425) Cornelia (257) Silesia (386) Siegena and (41) Daphne, and due\u0000 to TNOs 1998BU48 and (529823) 2010 PP81. The positive detections for the objects (257)\u0000 Silesia (386) Siegena and (41) Daphne allow us to derive lower limits in the diameter of\u0000 the MBAs of 63.1 km, 166.2 km and 158.7 km and offsets in the astrometric position (Δαc\u0000 cosδc, Δδc) of 622.30 ± 0.83, 15.23 ± 9.88 mas, 586.06 ± 1.68, 43.03 ± 13.88 mas and\u0000 –413.44 ± 9.42, 234.05 ± 19.12 mas, respectively.","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":"6 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79278267","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：