Subaru (Japan)

Abstract We conducted a two-band imaging survey observation using the Subaru Telescope and its wide-field camera, Suprime-Cam, to study the visible colors and size distribution of Jupiter’s Trojan asteroids. The survey covered an area around Jupiter’s L4 Lagrange point totaling 9.2 square degrees. We detected 120 Trojan asteroids in this survey. From these Trojan asteroids, we extracted 44 unbiased samples with absolute magnitudes in the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>g</mml:mi> <mml:mo accent="false">′</mml:mo> </mml:math> band ranging from 12.9 to 16.9 mag (corresponding to diameter ranges of approximately ∼3–16 km assuming an albedo of 0.05) and analyzed their <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>g</mml:mi> <mml:mo accent="false">′</mml:mo> <mml:mo>−</mml:mo> <mml:mi>i</mml:mi> <mml:mo accent="false">′</mml:mo> </mml:math> color and size distributions. Large Jupiter Trojan asteroids are known to be classified into two color groups, “red” and “less red.” We found that such bimodality in the color distribution is absent for small Jupiter Trojan asteroids, which is consistent with previous studies. Previous studies have also shown that these two groups have different slopes in the magnitude distributions from each other, which was explained by conversion of red objects to less-red fragments through catastrophic disruptions. In contrast, we found that the size frequency distributions of our two sample groups divided by the color of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>g</mml:mi> <mml:mo accent="false">′</mml:mo> <mml:mo>−</mml:mo> <mml:mi>i</mml:mi> <mml:mo accent="false">′</mml:mo> </mml:math> = 0.7 (in AB magnitude) are quite similar. Our results can provide new insights into collisional evolution of color and size distribution of small Jupiter Trojans.

The role of regional diversification versus the effect of migration in generating local species assemblages remains poorly known. Here, we contribute to the understanding of the role of colonisation and in situ diversification by studying an assemblage of miniaturised microhylid frogs of the genus Stumpffia Boettger, 1881, of which six species have been known to occur on Montagne d’Ambre, a volcanic mountain in the north of Madagascar. These six species are distributed over different, partly overlapping elevational levels. We examined this assemblage based on molecular data (16S mtDNA and Rag1 nDNA), new data on the elevational distribution among local Stumpffia species, and differences in advertisement calls. Our results revealed several genetic lineages constituting distinct species, including another species record for the mountain, S. mamitika Rakotoarison et al., 2017, as well as the new candidate species Stumpffia sp. aff. angeluci . This brings the total number of described species known to occur on the mountain to seven, four of which are micro-endemic. Our data indicate that one clade, consisting of four species, has arisen in situ as a microendemic radiation. We discuss alternative evolutionary scenarios for the biogeographic origin of the observed Stumpffia species.

Abstract In modern industrial societies, animals including humans are frequently exposed to external mechanical oscillations such as whole-body (WB) vibration. To ensure postural stability and effective movement, animals must appropriately regulate their responses to such vibratory disturbances. Therefore, understanding how animals respond to vibration is of growing importance. However, compared with humans, knowledge of mouse responses to WB vibration remains limited, as previous studies have primarily examined anesthetized or euthanized mice. Here, we used high-speed video-based quantitative analyses to characterize body part movements in both awake and anesthetized mice under vertical, longitudinal, and lateral WB vibration. Awake mice exhibited lower resonance frequencies and smaller displacement amplitudes than anesthetized mice during both vertical and lateral WB vibration, whereas longitudinal WB vibration produced minimal differences. These results indicate that the active neuro-musculoskeletal (NMS) system contributes to postural stability in a vibration axis-dependent manner. Axis-specific vibration control may reflect an evolutionarily acquired balance between postural stability and locomotor efficiency. Vibration modeling further suggests that the NMS system acts as a vibration absorber by reducing stiffness and providing feedback-controlled active damping, analogous to active vehicle suspensions. Behavioral preference tests revealed that mice selectively avoid vertical WB vibration at specific frequencies, but not lateral or longitudinal vibration, regardless of resonance frequencies. These findings suggest that resonated body part displacement during WB vibration do not directly determine vibration discomfort, and that vertical WB vibration along the gravitational axis exerts a distinct impact on postural control and behavior in mice. This study provides new insights into the biomechanics and behavior of quadrupeds exposed to WB vibration, with analogies to four-wheeled vehicles offering a useful perspective.

To describe the technique and surgical outcomes of a modified inverted internal limiting membrane (ILM) flap technique, using perfluorocarbon liquid (PFCL) without creating iatrogenic retinal breaks in the management of macular hole-associated retinal detachment. This retrospective study was approved by the Ethics Committee of Akita University Hospital. Eight patients with macular hole-associated retinal detachment underwent pars plana vitrectomy with the novel PFCL-assisted inverted ILM flap technique. Subretinal fluid was drained through the macular hole using a soft-tip needle, and ILM staining was performed after fluid-air exchange. PFCL was applied to stabilize the retina, and ILM peeling was completed under PFCL with improved visibility. The procedure concluded with air-fluid exchange and tamponade using silicone oil or gas. Patients maintained a face-down position postoperatively for 1 day. All eight patients achieved initial retinal reattachment and macular hole closure without intraoperative or postoperative complications. After 12 months of follow-up, macular hole closure and retinal reattachment were maintained in all cases. This novel technique avoids iatrogenic breaks, reducing epiretinal membrane risk and secondary macular hole formation. The PFCL-assisted ILM manipulation ensures stability and minimizes retinal damage. The method is safe, effective, and promising for macular hole-associated retinal detachment treatment in this small series.

Abstract We studied an outburst of the Andromedid meteor shower on 2021 November 28, by detecting meteors from a live-streaming video camera on the Subaru Telescope site at the summit of Mauna Kea, Hawaii Island. We detected 148 Andromedid meteors and 202 non-Andromedid meteors in a 6 h observation from 05:00 to 11:00 UT. From our observations, there was a peak of activity from 06:00 to 07:00 UT. The average magnitude of the Andromedid meteors was +3.9, and many of them were faint. The radiant was concentrated in a compact area. We point out that this outburst may be due to an encounter with a dust trail caused by dust ejected from comet 3D/Biela in 1655.

Electroaerodynamics (EAD) is a phenomenon that generates a gas motion by applying high voltage between electrodes. One method of creating thrust with EAD is the use of the corona discharge, which is a self-sustaining discharge. Since it does not require any moving parts, the corona discharge produces thrust robustly and quietly. Therefore, this thrust system is expected to be utilized as the thrust source for drones. However, since the relationship between thrust and applied voltage is nonlinear, dealing with this problem in control is indispensable. Although some studies have been conducted on control methods with the corona discharge, few have been performed on multi-degrees of freedom (DOF) control based on theoretical modeling, which is essential for achieving attitude control during flight. Thus, this paper proposes a control system based on theoretical modeling to realize 2-DOF height and angle control. This study utilizes the idea of differential mode and voltage range limitations and introduces a disturbance observer (DOB) to construct a control system. Two simulations are conducted to verify the effectiveness of the proposal. The first simulation shows that the proposal can follow the command value with small errors, indicating the possibility of multi-DOF control. The second simulation revealed that the proposal significantly suppressed attitude change under disturbance and contributed to improved responsiveness.

Context. Photonic lanterns (PLs) are waveguide devices enabling high-throughput single-mode spectroscopy and high angular resolution. Aims. We aim to present the first on-sky demonstration of a PL operating in visible light, to measure its throughput and assess its potential for high-resolution spectroscopy of compact objects. Methods. We used the SCExAO instrument (a double-stage extreme adaptive optics system installed at the Subaru Telescope) and FIRST mid-resolution spectrograph (R 3000) to test the visible capabilities of the PL on internal source and on-sky observations. Results. The best averaged coupling efficiency over the PL field of view was measured at 51% ± 10%, with a peak at 80%. We also investigated the relationship between coupling efficiency and the Strehl ratio for a PL, comparing them with those of a single-mode fiber (SMF). Findings show that in the adaptive optics regime a PL offers a better coupling efficiency performance than an SMF, especially in the presence of low-spatial-frequency aberrations. We observed Ikiiki (α Leo – mR = 1.37) and ‘Aua (α Ori – mR = −1.17) at a frame rate of 200 Hz. Under median seeing conditions (about 1 arcsec measured in the H band) and large tip or tilt residuals (over 20 mas), we estimated an average light coupling efficiency of 14.5% ± 7.4%, with a maximum of 42.8% at 680 nm. We were able to reconstruct both star’s spectra, containing various absorption lines. Conclusions. The successful demonstration of this device opens new possibilities in terms of high-throughput single-mode fiber-fed spectroscopy in the visible. The demonstrated on-sky coupling efficiency performance would not have been achievable with a single SMF injection setup under similar conditions, partly because the residual tip or tilt alone exceeded the field of view of a visible SMF (18 mas at 700 nm). This emphasizes the enhanced resilience of PL technology to such atmospheric disturbances. The additional capabilities in high angular resolution are also promising but still have to be demonstrated in a forthcoming investigation.

A method is presented for enhancing the steering maneuvers of human drivers using peripheral visual information generated based on the vehicle’s lateral positions on the road. Human drivers control vehicles mainly using visual feedback information received from the road. However, such feedback may sometimes become degraded due to various reasons. On the other hand, recent advances in sensory technologies make it possible to detect vehicle behavior on the road quite stably. In this paper, we investigate a way to compensate such impaired feedback using artificial visual stimuli. A series of LED devices were installed in the car’s doors to display the stimuli. We designed three types of illumination patterns (flow, position, and width conditions) that react to the current lateral position of the vehicle. Simulated driving studies were conducted to evaluate the effect of each pattern on the driver’s control of the vehicle. As a result, we found that the presenting the artificial visual stimuli without explanation could significantly reduce inappropriate steering maneuvers in the degraded feedback situations.

An inner component misaligned from an outer component in a protoplanetary disk can result in the former casting shadows on the latter. We present a new instance of shadowing on the outer disk around a very-low-mass star, ZZ Tau IRS. Through the analysis of near-infrared (NIR) archival data at λ = 1.6 μm acquired with the Wide Field Camera 3 on the Hubble Space Telescope, we identified brightness asymmetries in the top and bottom halves of the highly inclined outer disk, separated by a dark lane. The brighter sides in the top and bottom halves are on the opposite sides, which we attributed to shadows cast by a misaligned inner disk. Radiative transfer modeling of the system with a misaligned angle of 15 deg between the inner and outer disks well reproduced the observations. Additionally, we found an elevated brightness temperature of 12CO (3–2) at r ∼ 30 au on the brighter side in NIR wavelengths in the top half disk, which can be explained by the shadowing effect too. While the origin of the misaligned inner disk remains unclear, future monitoring observations to search for temporal variations in brightness asymmetries will likely provide useful clues.