To understand the effects of the initial rotation on the evolution of the tidally limited clusters with mass spectrum, we have performed N-body simulations of the clusters with different initial ...rotations and compared the results with those of the Fokker-Planck (FP) simulations. We confirmed that the cluster evolution is accelerated by not only the initial rotation but also the mass spectrum. For the slowly rotating models, the time evolutions of mass, energy and angular momentum show good agreements between N-body and FP simulations. On the other hand, for the rapidly rotating models, there are significant differences between these two approaches at the early stage of the evolutions because of the development of bar instability in N-body simulations. The shape of the cluster for N-body simulations becomes tri-axial or even prolate, which cannot be produced by the two-dimensional FP simulations. The total angular momentum and the total mass of the cluster decrease rapidly while bar-like structure persists. After the rotational energy becomes smaller than the critical value for the bar instability, the shape of the cluster becomes nearly axisymmetric again, and follows the evolutionary track predicted by the FP equation. We have confirmed again that the energy equipartition is not completely achieved when M
2/M
1(m
2/m
1)3/2 > 0.16. By examining the angular momentum at each mass component, we found that the exchange of angular momentum between different mass components occurs, similar to the energy exchange leading to the equipartition.
The Korean Pathfinder Lunar Orbiter (KPLO)-MAGnetometer (KMAG) consists of three triaxial fluxgate sensors (MAG1, MAG2, and MAG3) that measure the magnetic field around the Moon. The three sensors ...are mounted in the order MAG3, MAG2, and MAG1 inside a 1.2 m long boom, away from the satellite body. Before it arrived on the Moon, we compared the magnetic field measurements taken by DSCOVR and KPLO in solar wind to verify the measurement performance of the KMAG instrument. We found that there were artificial disturbances in the KMAG measurement data, such as step-like and spike-like disturbances, which were produced by the spacecraft body. To remove spacecraft-generated disturbances, we applied a multi-sensor method, employing the gradiometer technique and principal component analysis, using KMAG magnetic field data, and confirmed the successful elimination of spacecraft-generated disturbances. In the future, the proposed multi-sensor method is expected to clean the magnetic field data measured onboard the KPLO from the lunar orbit.
Korea Pathfinder Lunar Orbiter (KPLO) is South Korea’s first space exploration mission, developed by the Korea Aerospace Research Institute. It aims to develop technologies for lunar exploration, ...explore lunar science, and test new technologies. KPLO was launched on August 5, 2022, by a Falcon-9 launch vehicle from cape canaveral space force station (CCSFS) in the United States and placed on a ballistic lunar transfer (BLT) trajectory. A total of four trajectory correction maneuvers were performed during the approximately 4.5-month trans-lunar cruise phase to reach the Moon. Starting with the first lunar orbit insertion (LOI) maneuver on December 16, the spacecraft performed a total of three maneuvers before arriving at the lunar mission orbit, at an altitude of 100 kilometers, on December 27, 2022. After entering lunar orbit, the commissioning phase validated the operation of the mission mode, in which the payload is oriented toward the center of the Moon. After completing about one month of commissioning, normal mission operations began, and each payload successfully performed its planned mission. All of the spacecraft operations that KPLO performs from launch to normal operations were designed through the system operations design process. This includes operations that are automatically initiated post-separation from the launch vehicle, as well as those in lunar transfer orbit and lunar mission orbit. Key operational procedures such as the spacecraft’s initial checkout, trajectory correction maneuvers, LOI, and commissioning were developed during the early operation preparation phase. These procedures were executed effectively during both the early and normal operation phases. The successful execution of these operations confirms the robust verification of the system operation.
We have completed a spectroscopic survey of X-ray point sources in eight low-redshift clusters of galaxies (0.05 < z < 0.31) and have identified 40 cluster members with broadband (0.3-8 keV) X-ray ...luminosities between L sub(X) = 8 x 10 super(40) and 4 x 10 super(43) ergs s super(-1). There are between two and 10 X-ray sources per cluster. We use visible-wavelength emission lines, X-ray spectral shapes, and multiwavelength flux ratios to determine that at least 35 of these galaxies are active galactic nuclei (AGNs). From our spectroscopic survey of other candidate cluster members we estimate that the AGN fraction f sub(A) is 65% for cluster galaxies more luminous than M sub(R) = -20 mag hosting AGNs with broadband X-ray luminosities above L sub(X) = 10 super(41) ergs s super(-1), or f sub(A)(M sub(R) < -20; L sub(X) > 10 super(41)) 6 5%. We stress that additional, lower luminosity AGNs are expected to be present in the M sub(R) < -20 mag cluster members. Our data unambiguously demonstrate that cluster galaxies host AGNs more frequently than previously expected. Only four of these galaxies have obvious visible-wavelength AGN signatures, even though their X-ray luminosities are too high for their X-ray emission to be due to populations of low-mass X-ray binaries or hot, gaseous halos. We attribute the significant difference in visible and X-ray AGN identification to dilution of low-luminosity AGN spectral signatures by host galaxy starlight and/or obscuration of accretion onto the central, supermassive black hole.
We present a systematic study of the low-mass X-ray binary (LMXB) populations of six elliptical galaxies, aimed at investigating the detected LMXB-globular cluster (GC) connection. We utilize Chandra ...archival data to identify X-ray point sources and HST archival data supplemented by ground observations to identify 6173 GCs. After screening and cross-matching, we associate 209 LMXBs with red GC (RGCs) and 76 LMXBs with blue GCs (BGCs), while we find no optical GC counterpart for 258 LMXBs. This is the largest GC-LMXB sample studied so far. We confirm previous reports suggesting that the fraction of GCs associated with LMXBs is 63 times larger in RGCs than in BGCs, indicating that metallicity is a primary factor in the GC LMXB formation. We find that GCs located near the galaxy center have a higher probability of harboring LMXBs than those in the outskirts, suggesting that there must be another parameter (in addition to metallicity) governing LMXB formation in GCs. This second parameter, dependent on the galactocentric distance, may be a distance dependent encounter rate. We find no significant differences in the shape of X-ray luminosity function, L sub(X)/L sub(V) distribution, X-ray spectra among RGC, BGC, and field LMXBs. The similarity of the X-ray spectra is inconsistent with the irradiation-induced stellar wind model prediction. The similarity of the X-ray luminosity functions (XLFs) of GC LMXBs and field LMXBs indicates that there is no significant difference in the fraction of black hole binaries present. We cannot either prove or reject the hypothesis that all LMXBs were formed in GCs.
We present a photometric study of the GCs in the giant elliptical galaxy M60 in the Virgo Cluster, based on deep, relatively wide field Washington image CCD images. The CMD reveals a significant ...population of GCs in M60 and a large number of young luminous clusters in NGC 4647, a small companion spiral northwest of M60. The color distribution of the GCs in M60 is clearly bimodal, with a blue peak at image and a red peak at image. We derive two new transformation relations between the image color and Fe/H using the data for the GCs in our Galaxy and M49. Using these relations, we derive the metallicity distribution of the GCs in M60, which is also bimodal: a dominant metal-poor component with center at image, and a weaker metal-rich component with center at image. The radial number density profile of the GCs is more extended than that of the stellar halo, and the radial number density profile of the blue GCs is more extended than that of the red GCs. The number density maps of the GCs show that the spatial distribution of the blue GCs is roughly circular, while that of the red GCs is elongated similarly to that of the stellar halo. We estimate the total number of the GCs in M60 to be image and the specific frequency to be image. The mean color of the bright blue GCs gets redder as they get brighter in both the inner and outer region of M60. This blue tilt is seen also in the outer region of M49, the brightest Virgo galaxy. Implications of these results are discussed.
Korea Pathfinder Lunar Orbiter (KPLO) is South Korea's first space exploration mission, developed by the Korea Aerospace Research Institute. It aims to develop technologies for lunar exploration, ...explore lunar science, and test new technologies. KPLO was launched on August 5, 2022, by a Falcon-9 launch vehicle from cape canaveral space force station (CCSFS) in the United States and placed on a ballistic lunar transfer (BLT) trajectory. A total of four trajectory correction maneuvers were performed during the approximately 4.5-month trans-lunar cruise phase to reach the Moon. Starting with the first lunar orbit insertion (LOI) maneuver on December 16, the spacecraft performed a total of three maneuvers before arriving at the lunar mission orbit, at an altitude of 100 kilometers, on December 27, 2022. After entering lunar orbit, the commissioning phase validated the operation of the mission mode, in which the payload is oriented toward the center of the Moon. After completing about one month of commissioning, normal mission operations began, and each payload successfully performed its planned mission. All of the spacecraft operations that KPLO performs from launch to normal operations were designed through the system operations design process. This includes operations that are automatically initiated post-separation from the launch vehicle, as well as those in lunar transfer orbit and lunar mission orbit. Key operational procedures such as the spacecraft's initial checkout, trajectory correction maneuvers, LOI, and commissioning were developed during the early operation preparation phase. These procedures were executed effectively during both the early and normal operation phases. The successful execution of these operations confirms the robust verification of the system operation.
We present wide-field multiband photometry of globular cluster (GC) systems in NGC 1399, NGC 1404, and NGC 1387 located in the central region of the Lornax galaxy cluster. Observation was carried out ...through U, B, V, and I bands, which marks one of the widest and deepest U-band studies on extragalactic GC systems. The present E-band photometry enables us to significantly reduce the contamination by a factor of two for faint sources (V sub(0) ~ 23.5). The main results based on some 2000 GC candidates around NGC 1399, NGC 1404, and NGC 1387 are as follows: (1) the GC system in each galaxy exhibits bimodal color distributions in all colors examined, but the shape of color histograms varies systematically depending on colors; (2) NGC 1399 shows that the mean colors of both blue and red GCs become bluer with increasing galactocentric radius; (3) NGC 1399 shows overabundance of GCs in the directions of NGC 1404 and NGC 1387, indicating their ongoing interactions; and (4) NGC 1399 also exhibits a ~0'.5 offset between the center of the inner GC distribution and the galaxy's optical center, suggesting that NGC 1399 is not yet dynamically relaxed and may be undergoing merger events.
The Korea Pathfinder Lunar Orbiter (KPLO), the first South Korea lunar exploration probe, successfully arrived at the Moon on December, 2022 (UTC), following a 4.5-month ballistic lunar transfer ...(BLT) trajectory. Since the launch (4 August, 2022), the KPLO magnetometer (KMAG) has carried out various observations during the trans-lunar cruise phase and a 100 km altitude lunar polar orbit. KMAG consists of three fluxgate magnetometers capable of measuring magnetic fields within a ± 1,000 nT range with a resolution of 0.2 nT. The sampling rate is 10 Hz. During the originally planned lifetime of one year, KMAG has been operating successfully while performing observations of lunar crustal magnetic fields, magnetic fields induced in the lunar interior, and various solar wind events. The calibration and offset processes were performed during the TLC phase. In addition, reliabilities of the KMAG lunar magnetic field observations have been verified by comparing them with the surface vector mapping (SVM) data. If the KPLO's mission orbit during the extended mission phase is close enough to the lunar surface, KMAG will contribute to updating the lunar surface magnetic field map and will provide insights into the lunar interior structure and lunar space environment.
The Korea Pathfinder Lunar Orbiter (KPLO), the first South Korea lunar
exploration probe, successfully arrived at the Moon on December, 2022 (UTC),
following a 4.5-month ballistic lunar transfer ...(BLT) trajectory. Since the
launch (4 August, 2022), the KPLO magnetometer (KMAG) has carried out various
observations during the trans-lunar cruise phase and a 100 km altitude lunar
polar orbit. KMAG consists of three fluxgate magnetometers capable of measuring
magnetic fields within a ± 1,000 nT range with a resolution of 0.2 nT.
The sampling rate is 10 Hz. During the originally planned lifetime of one year,
KMAG has been operating successfully while performing observations of lunar
crustal magnetic fields, magnetic fields induced in the lunar interior, and
various solar wind events. The calibration and offset processes were performed
during the TLC phase. In addition, reliabilities of the KMAG lunar magnetic
field observations have been verified by comparing them with the surface vector
mapping (SVM) data. If the KPLO’s mission orbit during the extended
mission phase is close enough to the lunar surface, KMAG will contribute to
updating the lunar surface magnetic field map and will provide insights into the
lunar interior structure and lunar space environment.
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