[معهد كامياما لعلوم الفضاء]Current status of WINERED near-infrared high dispersion spectroscopy: new research results are published one by one |

The WINERED High Dispersion Near-Infrared Spectrometer, which the Kamiyama Observatory of Kyoto Sangyo University is continuing to develop in collaboration with the University of Tokyo Graduate School and related companies, is currently mounted on the 6.5-meter Magellan Telescope at the Las Campanas Observatory in the Republic. Chile is still used as one of the highest infrared monitors in the world. Observations are usually performed twice a year, usually in the spring and fall, over a period of two weeks. Two monitoring periods were scheduled for fiscal year 2020, and the monitoring operations were conducted this spring from April 15 to 30, and were successfully completed. Although we were experiencing bad weather this time, we were able to get good enough data on a clear night.

The WINERED High Dispersion Near-Infrared Spectrometer is an astronomical observation spectrometer that exhibits high wavelength resolution at wavelengths of about 1 micron, where the absorption and emission lines of various atoms and molecules are concentrated. It has the highest sensitivity in the world, and is used on a variety of astronomical topics in conjunction with the 6.5-meter Magellan telescope. This time, we will highlight some of these topics and present recent findings.

1. Illustrating chemical evolution in the Milky Way using Cepheid variable stars
2. Clarifying the relationship between the metal content in the atmosphere and the dissipation of exoplanets in the atmosphere
3. Explaining the process of gas dissipation in protoplanetary disks

In addition to these research results, there are also observational results of globular clusters near the center of the Milky Way using the Magellan Telescope (Minetti et al. 2024) and observation results from the 3.6 m diameter NTT telescope (La Silla Observatory, Republic of Chile), which was in operation before WINERED was transferred to the Magellan Telescope (Mizumoto et al. 2024), a development paper on the WARP program to organize complex observational data obtained using WINERED and convert them into spectral data that is easier for researchers to use (Hamano et al. 2024), research results related to WINERED are published one after another as research papers. Observations with the Magellan Telescope require preparations for observations in extremely harsh environments due to its high location, but astronomers alone cannot make such preparations and maintain and manage the equipment. During each spring and fall observing season, Kamiyama Observatory technical staff from Japan travel abroad for approximately one to two months to provide observing support and equipment upgrades. Academic results such as those presented here can only be achieved through the collaboration of professionals from different positions.

Noriyuki Matsunaga (an assistant professor at the Graduate School of the University of Tokyo and a visiting researcher at our university) plays a central role in exploring the metallicity of Cepheid variable stars in our Milky Way Galaxy. Cepheid variable stars are a type of variable star whose brightness fluctuates. They play an important role in astronomy, as their true brightness can be determined by their period of change. Furthermore, since it is possible to determine to some extent the age at which light fluctuation phenomena occur (the number of years since a star was born), it can provide clues to our Milky Way's past. The preliminary results have already been published in the US Astrophysical Journal, and the history of nucleosynthesis near the center of the Milky Way has become clear. Cepheid variable stars are also one of the research subjects of astrophysicist Dr. Shunma Araki, founder of Kyoto Sangyo University, and observational research on Cepheid variable stars is carried out by WINERED, which was developed at the Kamiyama Observatory, proving that this kind of astronomical research is a tradition at our university.

Magazine link (in English)
Matsunaga et al. “Classical Cepheid Minerals in the Inner Galactic Disk”

Many exoplanets continue to be discovered to this day. Among these planets, several gaseous planets were found orbiting close to the central star, and observations were made that the planet's atmosphere overheated due to ultraviolet radiation and X-rays from the central star, and the flow of the atmosphere into space was. Dr. Visapragada and his colleagues at the Harvard-Smithsonian Center for Astrophysics used the WINERED program to observe an exoplanet called LTT 9779b, which has a mass similar to that of Neptune in our solar system. The planet is thought to be very hot because it orbits close to its central star, but observations with WINERED have not confirmed any gas flow as expected theoretically. Dr. Visapragada and his colleagues believe this is because LTT 9779b's atmosphere is relatively rich in heavy elements other than gaseous components such as hydrogen and helium, which are the main components. These observational results are an example of the synergistic effect of combining the highly sensitive WINERED telescope and the Large Diameter Magellan Telescope.

Magazine link (in English)
Visapragada et al. “No high-resolution detection of escaping helium in superheated Neptune LTT 9779b: evidence for weak evaporation”

The research was led by Mr. Haruki Kato (who was then a graduate student in the doctoral course at the Graduate School of Science at our university) and Ms. Chikako Yasui (an assistant professor at the National Astronomical Observatory of Japan and a visiting researcher at our university). In the field of protoplanetary systems, where planets form around stars, we have created a new way to study the disk. A protoplanetary disk is a disk of gas and dust that forms around a nascent star. It is believed that planets like Earth are born when small particles of dust repeatedly collide and collect within this disk, but at some point the gas explodes and disappears. Using WINERED, we observed the special light (the forbidden line) emitted by nitrogen atoms and found that it was emitted by winds blowing from the disk (disk winds). The results were published in the American Astrophysical Journal, the Astrophysical Journal. This research result is based on data obtained when WINERED was installed on the 1.3-meter Araki telescope at the Kamiyama Observatory of our university. The Araki telescope is a small telescope compared to the world's most advanced telescopes such as the Magellan Telescope, but by developing unique observing instruments like WINERED on our own, we have been able to achieve such world-leading results.

Magazine link (in English)
Katoh et al. “[N i] 10400/10410 Å lines as potential tools for tracking disc winds in a young, intermediate-mass star”