arXiv subjects

Jun Matsumoto

Publications and source records attributed to Jun Matsumoto.

5 recordsLinked to original sources

arXiv2026

Science operation, data handling, and ground support system of the SOLAR-C mission

SOLAR-C is an international solar-observing satellite mission led by Japan Aerospace Exploration Agency (JAXA). It aims to elucidate mass and energy transport in solar atmospheres through extreme ultraviolet (EUV) spectroscopy. The mission carries the EUV High-throughput Spectroscopic Telescope (EUVST) and the Solar Spectral Irradiance Monitor (SoSpIM), enabling comprehensive observations across a wide temperature range (10^4 K to 10^7 K) with minimum temperature gaps and high spatial and temporal resolution. To achieve its science objectives regarding atmospheric heating and solar flare eruptions, SOLAR-C implements a flexible and responsive operational procedure and a data processing system, while building on the heritage of the Hinode and IRIS satellites. The Chief Observer creates observation timelines that include core observation plans and approved proposed plans while taking into account the solar activity levels. A SpaceWire communication architecture is employed onboard the spacecraft, and a method is implemented in which the mission instrument temporarily acts as the network master during data transfer to support the high data rate requirements. Telemetry is downlinked at ground stations worldwide and gathered at the Institute of Space and Astronautical Science, JAXA. The EUVST data are calibrated at the SOLAR-C Science Center at Nagoya University, while the SoSpIM data are calibrated at the Processing and Archiving Facility before being integrated into the science data products. The data will be made publicly available immediately. The integrated operational scheme for this mission is expected to advance our understanding of solar atmospheric heating and flare processes.

astro-ph.SR↗

arXiv2026

Criteria and Curvatures for Singularities of Finite Multiplicities of Curves in $\boldsymbol{R}^N$

First, this paper presents a systematic procedure for constructing criteria for singularities of curves of finite multiplicities in $\boldsymbol{R}^N$. Based on this method, we provide explicit criteria for singularities of multiplicities two, three, and four, including specific cusps appearing only in dimensions three or higher. Furthermore, we generalize the normalized curvature functions and the cuspidal curvature to singular curves in $\boldsymbol{R}^N$. Using these generalized curvatures, we reinterpret the existence and uniqueness theorem given by Fukui for curves in $\boldsymbol{R}^N$ of finite multiplicities.

math.DG↗

arXiv2026

Complete minimal surfaces of finite total curvature on punctured spheres with totally ramified value number greater than $2$

Motivated by Osserman's problem on the number $D_g$ of omitted values of the Gauss map of a complete minimal surface with finite total curvature in $\boldsymbol{R}^3$, its totally ramified value number $ν_g$ (referred to in this paper as the \emph{total weight of totally ramified values}) has attracted significant interest. The value of $ν_g$ provides more detailed information than the number of omitted values alone. In 2006, Kawakami first found that a minimal surface defined on the three-punctured Riemann sphere, originally constructed by Miyaoka and Sato, satisfies $D_g = 2$ and $ν_g = 2.5 > 2$. Subsequently, in 2024, Kawakami and Watanabe gave another minimal surface defined on the four-punctured Riemann sphere that also satisfies $D_g = 2$ and $ν_g = 2.5$. To date, these remain the only two known examples of such surfaces satisfying $ν_g > 2$. In this paper, we provide a systematic construction of meromorphic functions on punctured Riemann spheres that satisfy $ν_g > 2$. As a consequence, we obtain the following results for complete minimal surfaces of finite total curvature with $ν_g = 2.5$ within the topological types of the known examples: (1) For the three-punctured sphere, we prove the uniqueness of Miyaoka--Sato's example. (2) For the four-punctured sphere, we completely determine the surfaces with $D_g=2$ and $ν_g = 2.5$, which include examples other than Kawakami--Watanabe's one. (3) Furthermore, we construct a new example on the four-punctured sphere satisfying $D_g=1$ and $ν_g = 2.5$.

math.DG↗

arXiv2025

A class of affine maximal surfaces with singularities and its relationship with minimal surface theory

We study a global theory of affine maximal surfaces with singularities, which are called affine maximal maps and defined by Aledo--Mart\' inez--Mil\' an. In this paper, we define a special subclass of such surfaces other than improper affine fronts, called \emph{affine maxfaces}, and investigate their global properties with respect to certain notions of completeness. In particular, by applying Euclidean minimal surface theory, we show that ``complete'' affine maxfaces satisfy an Osserman-type inequality. Moreover, one can also observe that affine maxfaces are in a class that does not contain non-trivial improper affine fronts. We also provide examples of such surfaces which are related to Euclidean minimal surfaces.

math.DG↗

arXiv2025

The classification of complete improper affine spheres with singularities of low total curvature and new examples

We provide a classification of complete improper affine spheres with singularities (say \emph{improper affine fronts}) in unimodular affine three-space $\boldsymbol{R}^3$ whose total curvature is greater than or equal to $-6π$, and a partial classification in the case of total curvature $-8π$. For the case of total curvature $-8π$, we give a complete classification for genus $0$ case and show the existence of an example and a one parameter family with genus $1$. We also study the asymptotic behavior of embedded ends of complete improper affine fronts. Moreover, we give new examples for this class of surfaces, including one which satisfies the equality condition of an Osserman-type inequality and is of positive genus.

math.DG↗