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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Astronomy and Space Sciences
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Journal DOI :
The Korean Space Science Society
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Volume & Issues
Volume 29, Issue 4 - Dec 2012
Volume 29, Issue 3 - Sep 2012
Volume 29, Issue 2 - Jun 2012
Volume 29, Issue 1 - Mar 2012
Selecting the target year
Comparison of the Characteristics of Precipitable Water Vapor Measured by Global Positioning System and Microwave Radiometer
Sohn, Dong-Hyo ; Park, Kwan-Dong ; Won, Ji-Hye ; Cho, Jung-Ho ; Roh, Kyoung-Min ;
Journal of Astronomy and Space Sciences, volume 29, issue 1, 2012, Pages 1~10
DOI : 10.5140/JASS.2012.29.1.001
In this study, global positioning system (GPS)-derived precipitable water vapor (PWV) and microwave radiometer (MWR)-measured integrated water vapor (IWV) were compared and their characteristics were analyzed. Comparing those two quantities for two years from August 2009, we found that GPS PWV estimates were larger than MWR IWV. The average difference over the entire test period was 1.1 mm and the standard deviation was 1.2 mm. When the discrepancies between GPS PWV and MWR IWV were analyzed depending on season, the average difference was 0.7 mm and 1.9 mm in the winter and summer months, respectively. Thus, the average difference was about 2.5 times larger in summer than that in winter. However, MWR IWV measurements in the winter months were over-estimated than those in the summer months as the water vapor content got larger. The results of the diurnal analysis showed that MWR IWV was underestimated in the daytime, showing a difference of 0.8 mm. In the early morning hours, MWR IWV has a tendency to be over-estimated, with a difference of 1.3 mm with respect to GPS PWV.
A Study on the Collision Avoidance Maneuver Optimization with Multiple Space Debris
Kim, Eun-Hyouek ; Kim, Hae-Dong ; Kim, Hak-Jung ;
Journal of Astronomy and Space Sciences, volume 29, issue 1, 2012, Pages 11~21
DOI : 10.5140/JASS.2012.29.1.011
In this paper, the authors introduced a new approach to find the optimal collision avoidance maneuver considering multi threatening objects within short period, while satisfying constraints on the fuel limit and the acceptable collision probability. A preliminary effort in applying a genetic algorithm (GA) to those kinds of problems has also been demonstrated through a simulation study with a simple case problem and various fitness functions. And then, GA is applied to the complex case problem including multi-threatening objects. Two distinct collision avoidance maneuvers are dealt with: the first is in-track direction of collision avoidance maneuver. The second considers radial, in-track, cross-track direction maneuver. The results show that the first case violates the collision probability threshold, while the second case does not violate the threshold with satisfaction of all conditions. Various factors for analyzing and planning the optimal collision avoidance maneuver are also presented.
Thermal Analysis of TRIO-CINEMA Mission
Yoo, Jae-Gun ; Jin, Ho ; Seon, Jong-Ho ; Jeong, Yun-Hwang ; Glaser, David ; Lee, Dong-Hun ; Lin, Robert P. ;
Journal of Astronomy and Space Sciences, volume 29, issue 1, 2012, Pages 23~31
DOI : 10.5140/JASS.2012.29.1.023
Thermal analysis and control design are prerequisite essential to design the satellite. In the space environment, it makes satellite survive from extreme hot and cold conditions. In recent years CubeSat mission is developed for many kinds of purpose. Triplet Ionospheric Observatory (TRIO)-CubeSat for Ion, Neutral, Electron, MAgnetic fields (CINEMA) is required to weigh less than 3 kg and operate on minimal 3 W power. In this paper we describe the thermal analysis and control design for TRIO-CINEMA mission. For this thermal analysis, we made a thermal model of the CubeSat with finite element method and NX6.0 TMG software is used to simulate this analysis model. Based on this result, passive thermal control method has been applied to thermal design of CINEMA. In order to get the better conduction between solar panel and chassis, we choose aluminum 6061-T6 for the material property of standoff. We can increase the average temperature of top and bottom solar panels from
and decrease the average temperature of the magnetometer from
using black paint on the surface of the chassis, inside of top & bottom solar panels, and magnetometer.
Development of CINEMA Mission Uplink Communication System
Yoon, Na-Young ; Yoon, Se-Young ; Kim, Yong-Ho ; Yoon, Ji-Won ; Jin, Ho ; Seon, Jong-Ho ; Chae, Kyu-Sung ; Lee, Dong-Hun ; Lin, Robert P. ;
Journal of Astronomy and Space Sciences, volume 29, issue 1, 2012, Pages 33~40
DOI : 10.5140/JASS.2012.29.1.033
Triplet Ionospheric Observatory (TRIO) CubeSatforIon, Neutral, Electron MAgneticfields (CINEMA) is a CubeSat with the weight 3 kg that will be operated in the orbit conditions of about 800 km altitude and
inclination angle, using the S-band and ultra-high frequency (UHF)-band communication frequencies. Regarding the communication antenna loaded on the satellite, the two patch antennas has the downlink function in the S-band, whereas the two whip antennas has the function to receive the command sent by the ground station to the satellite in the UHF-band. The uplink ground station that communicates through the UHF-band with the CINEMA satellite was established at Kyung Hee University. The system is mainly composed of a terminal node controller, a transceiver, and a helical antenna. The gain of the helical antenna established at the Kyung Hee University ground station was 9.8 dBi. The output of the transceiver was set to be 5 W (6.9 dB) for the communication test. Through the far-field test of the established system, it was verified that the Roman characters, figures and symbols were converted into packets and transmitted to the satellite receiver in the communication speed of 9,600 bps.
A Search for Exoplanets in Short-Period Binary Star Systems
Kaitchuck, Ronald ; Turner, Garrison ; Childers, Joseph ;
Journal of Astronomy and Space Sciences, volume 29, issue 1, 2012, Pages 41~45
DOI : 10.5140/JASS.2012.29.1.041
This paper reports the progress of a search for exoplanets with S-type orbits in short-period binary star systems. The selected targets have stellar orbital periods of just a few days. These systems are eclipsing binaries so that exoplanet transits, if planets exist, will be highly likely. We report the results for seven binary star systems.
Constraining the Mass Loss Geometry of Beta Lyrae
Lomax, Jamie R. ;
Journal of Astronomy and Space Sciences, volume 29, issue 1, 2012, Pages 47~49
DOI : 10.5140/JASS.2012.29.1.047
Massive binary stars lose mass by two mechanisms: jet-driven mass loss during periods of active mass transfer and by wind-driven mass loss. Beta Lyrae is an eclipsing, semi-detached binary whose state of active mass transfer provides a unique opportunity to study how the evolution of binary systems is affected by jet-driven mass loss. Roche lobe overflow from the primary star feeds the thick accretion disk which almost completely obscures the mass-gaining star. A hot spot predicted to be on the edge of the accretion disk may be the source of beta Lyrae's bipolar outflows. I present results from spectropolarimetric data taken with the University of Wisconsin's Half-Wave Spectropolarimeter and the Flower and Cook Observatory's photoelastic modulating polarimeter instrument which have implications for our current understanding of the system's disk geometry. Using broadband polarimetric analysis, I derive new information about the structure of the disk and the presence and location of a hot spot. These results place constraints on the geometrical distribution of material in beta Lyrae and can help quantify the amount of mass lost from massive interacting binary systems during phases of mass transfer and jet-driven mass loss.
Modeling Gamma-Ray Emission From the High-Mass X-Ray Binary LS 5039
Owocki, Stan ; Okazaki, Atsuo ; Romero, Gustavo ;
Journal of Astronomy and Space Sciences, volume 29, issue 1, 2012, Pages 51~55
DOI : 10.5140/JASS.2012.29.1.051
A few high-mass X-ray binaries-consisting of an OB star plus compact companion-have been observed by Fermi and ground-based Cerenkov telescopes like High Energy Stereoscopic System (HESS) to be sources of very high energy (VHE; up to 30 TeV)
-rays. This paper focuses on the prominent
-ray source, LS 5039, which consists of a massive O6.5V star in a 3.9-day-period, mildly elliptical (
) orbit with its companion, assumed here to be an unmagnetized compact object (e.g., black hole). Using three dimensional smoothed particle hydrodynamics simulations of the Bondi-Hoyle accretion of the O-star wind onto the companion, we find that the orbital phase variation of the accretion follows very closely the simple Bondi-Hoyle-Lyttleton (BHL) rate for the local radius and wind speed. Moreover, a simple model, wherein intrinsic emission of
-rays is assumed to track this accretion rate, reproduces quite well Fermi observations of the phase variation of
-rays in the energy range 0.1-10 GeV. However for the VHE (0.1-30 TeV) radiation observed by the HESS Cerenkov telescope, it is important to account also for photon-photon interactions between the
-rays and the stellar optical/UV radiation, which effectively attenuates much of the strong emission near periastron. When this is included, we find that this simple BHL accretion model also quite naturally fits the HESS light curve, thus making it a strong alternative to the pulsar-wind-shock models commonly invoked to explain such VHE
-ray emission in massive-star binaries.
The Search for Binaries in Post-Asymptotic Giant Branch Stars: Do Binary Companions Shape the Nebulae?
Hrivnak, Bruce J. ;
Journal of Astronomy and Space Sciences, volume 29, issue 1, 2012, Pages 57~61
DOI : 10.5140/JASS.2012.29.1.057
Binary companions are often invoked to explain the axial and point symmetry seen in the majority of planetary nebulae and proto-planetary nebulae (PPNs). To explore this hypothesis, we have undertaken a long-term (20 year) study of light and velocity variations in PPNs. From the photometric study of 24 PPNs, we find that all vary in brightness, and from a subset of 12 carbon-rich PPNs of F-G spectral type we find periods of 35-155 days, with the cooler having the longer periods. The variations are seen to be due to pulsation; no photometric evidence for binarity is seen. A radial velocity study of a sub-sample of seven of the brightest of these shows that they all vary with the pulsation periods. Only one shows evidence of a longer-term variation that we tentatively identify as being due to a binary companion. We conclude that the present evidence for the binary nature of these PPNs is meager and that any undetected companions of these PPNs must be of low mass (< 0.25
) or long period (> 30 years).
Optical Observations with Milliarcsecond Resolution of Stars, Their Environments and Companions
Sanborn, Jason J. ; Zavala, Robert T. ;
Journal of Astronomy and Space Sciences, volume 29, issue 1, 2012, Pages 63~67
DOI : 10.5140/JASS.2012.29.1.063
Observations with milliarsecond resolution using the Navy Optical Interferometer have been obtained for a number of stellar systems which include high-mass binaries, eclipsing binaries, and radio stars. These observations also reveal the previously unseen companions in single-lined spectroscopic binaries via directly measured flux ratios. We will present examples of published and ongoing research efforts of these systems to illustrate how an optical interferometer contributes to our knowledge of stars, their environment, and companions. These studies include a conclusive revealing of the previously unseen companion in the single-lined binary
Herculis, the direct determination of orbital parameters in the wide and close orbits of Algol, and revealing the orbit of
Lyrae with spatially resolved images of the
The Penn Polarimeters
Koch, Robert H. ; Wolf, George W. ; Hull, Anthony B. ; Elias, Nicholas M. II ; Holenstein, Bruce D. ; Mitchell, Richard J. ;
Journal of Astronomy and Space Sciences, volume 29, issue 1, 2012, Pages 69~77
DOI : 10.5140/JASS.2012.29.1.069
This report describes the inception, development and extensive use over 30 years of elliptical polarimeters at the University of Pennsylvania. The initial Mark I polarimeter design utilized oriented retarder plates and a calcite Foster-Clarke prism as the analyzer. The Mark I polarimeter was used on the Kitt Peak 0.9 m in 1969-70 to accomplish a survey of approximately 70 objects before the device was relocated to the 0.72 m reflector at the Flower and Cook Observatory. Successive generations of automation and improvements included the early-80's optical redesign to utilize a photoelastic modulated wave plate and an Ithaco lock-in amplifier-the photoelastic modulating polarimeter. The final design in 2000 concluded with a fully remote operable device. The legacy of the polarimetric programs includes studies of close binaries, pulsating hot stars, and luminous late-type variables.
Robert H. Koch's Work on Lightweight Medium-Aperture Mirrors
Holenstein, Bruce D. ; Mitchell, Richard J. ;
Journal of Astronomy and Space Sciences, volume 29, issue 1, 2012, Pages 79~84
DOI : 10.5140/JASS.2012.29.1.079
After a visit by Peter Waddell from the University of Strathclyde, Glasgow, UK in 1991, Robert H. Koch launched a program at the University of Pennsylvania to build lightweight pneumatic membrane mirrors, initially for balloon flight observations where weight is at a premium. Mirror cells were fabricated from sizes 0.18 m to 1.77 m, and experiments conducted to characterize the mirror figure and stability. Most of the work stopped after Prof. Koch's retirement in 1996 until 2006 when the authors expressed an interest in building an array of medium-aperture portable telescopes. The program restarted in earnest at Gravic, Inc. in Malvern, PA in 2008 with Koch using his extensive observational astronomy experience to guide the fabrication of a fully operational 1.07 m membrane mirror telescope with an optical tube assembly weighing under 45 Kg. Residual wavefront aberrations remediation resulted in Koch and the authors investigating membrane tensioning techniques with different cell designs, active secondary wavefront correction, photometric algorithms for aberrated images, and the use of additional lightweight mirror substrates from the Alt-Az Initiative Group, such as foamed glass. The best result for the lightweight mirrors was a point spread function spot size of several arc seconds. A lightweight 1.6 m cast aluminum cell alt-az telescope was subsequently designed by Koch and the authors for prime focus use.
Imaging Stars by Performing Full-Stokes Optical Interferometric Polarimetry
Elias, Nicholas M. II ; Edel, Stanislav S. ; Jones, Carol E. ; Mackay, Frances E. ; Mozurkewich, David ; Jorgensen, Anders M. ; Schmitt, Henrique R. ;
Journal of Astronomy and Space Sciences, volume 29, issue 1, 2012, Pages 85~91
DOI : 10.5140/JASS.2012.29.1.085
Optical interferometry and polarimetry have separately provided new insights into stellar astronomy, especially in the fields of fundamental parameters and atmospheric models. We present: scientific justifications for "full-Stokes" optical interferometric polarimetry (OIP); updated instrument requirements; preliminary beam combiner designs; polarimeter design; end-to-end OIP data reduction; and realistic reimaged full-Stokes models of Be stars with a suitable number of telescopes plus noise sources. All of this work represents preliminary research to construct an OIP beam combiner.
Interactions in Massive Colliding Wind Binaries
Corcoran, Michael F. ;
Journal of Astronomy and Space Sciences, volume 29, issue 1, 2012, Pages 93~96
DOI : 10.5140/JASS.2012.29.1.093
There are observational difficulties determining dynamical masses of binary star components in the upper HR diagram both due to the scarcity of massive binary systems and spectral and photometric contamination produced by the strong wind outflows in these systems. We discuss how variable X-ray emission in these systems produced by wind-wind collisions in massive binaries can be used to constrain the system parameters, with application to two important massive binaries, Eta Carinae and WR 140.