Stars and Galaxies, Vol. 07 （2024年）

論文リスト：

Long-term evolution of the Hα emission line of Pleione between Jan 2009 and Mar 2023 in the BeSS database II. Detailed profile variation during the periastron phenomenon
Author：Junichi Katahira
著者の電子メールアドレス: atak@db3.so-net.ne.jp
Received 2024 September 28; Accepted 2024 November 13

Abstract：
Using the Hα double peak emission lines of Pleione in the BeSS database from January 2009 to March 2023, the following points are discussed: 1) A comparison of the emission line profile variations observed at each periastron passage of the companion star reveals a striking similarity in the patterns of variation over the period 2015–2021. 2) As the periastron passage of the companion is repeated, the blue emission wing becomes stronger than the red emission wing towards the end of the Be-shell phase. 3) The mechanistic regularity whereby the red emission peak becomes earlier and stronger than the blue emission peak for a short time at each periastron passage of the companion star is interpreted qualitatively in terms of both the periastron position of the companion and the position of the disk in the celestial plane, as well as the tidal action of the companion star.

　Key words：stars: Be star— stars: Pleione— stars: Be disk
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Deriving Metallicity and Atmospheric Parameters for the Fast-Rotating SB2 Binary HIP 103833: Addressing Challenges in Close Binary Spectroscopy
Author：Noriyuki KATOH
Affiliation : Graduate School of Human Development and Environment, Kobe University
著者の電子メールアドレス: noriyuki.k@panda.kobe-u.ac.jp
Received 2024 October 31; Accepted 2024 November 21

Abstract：
The spectrum of a close binary star is a composite of the spectra of both the primary and secondary stars. Furthermore, high stellar rotational velocities lead to the blending of absorption lines, which complicates the accurate measurement of equivalent widths. In this study, we focused on the SB2 spectroscopic binary HIP 103833, for which the atmospheric parameters (effective temperature, surface gravity) and stellar parameters (mass, radius, luminosity) are already established. Utilizing spectral data obtained from the Nayuta Telescope at Nishi-Harima Observatory and MALLS, we derived atmospheric parameters and metallicities based on the equivalent widths of iron absorption lines. The parameters obtained in this research closely align with those from previous studies, thereby supporting the reliability of our equivalent width measurements. Additionally, the stellar parameters derived from our atmospheric analysis are not expected to differ significantly from those obtained from orbital motions in previous studies.

　Key words：stars: abundances — binaries: close — techniques: spectroscopic
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三波長同時偏光撮像装置 MuSaSHI のぐんま天文台 150cm 望遠鏡搭載と観測
Installation of Multi-wavelength SimultaneouS High throughput Imager and polarimeter (MuSaSHI) for Multi-color Imaging Observations on the Gunma Astronomical Observatory 150cm Telescope
著者：金井 昂大1, 大朝 由美子1,2, 高橋 英則3, 橋本 修4, 田口 光5
所属： 1) 埼玉大学大学院 理工学研究科
2) 埼玉大学 教育学部
3) 東京大学大学院理学系研究科 附属天文学教育研究センター 木曽観測所
4) 日本スペースガード協会
5) 群馬県立ぐんま天文台
Authors：Takahiro KANAI1, Yumiko OASA1,2, Hidenori TAKAHASHI3, Osamu HASHIMOTO4, Hikaru TAGUCHI5
Affiliation： 1) Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura, Saitama, Saitama, 338-8570, Japan
2) Faculty of Education, Saitama University, 255 Shimo-Okubo, Sakura, Saitama, Saitama, 338-8570, Japan
3) Kiso Observatory, Institute of Astronomy, School of Science, the University of Tokyo, 10762-30 Mitake, Kiso-machi, Kiso-gun, Nagano, 397-0101, Japan
4) Bisei Spaceguard Center, 1716-3 Okura, Bisei, Ibara, Okayama 714-1411, Japan
5) Gunma Astronomical Observatory, 6860-86 Nakayama, Takayama, Agatsuma, Gunma 377-0702, Japan
著者の電子メールアドレス: s15pp223@gmail.com
Received 2024 October 31; Accepted 2024 December 5

概要：
高精度な多波長同時撮像観測を目的として、埼玉大学 SaCRA 望遠鏡カセグレン焦点 (F6.5) 用に開発され た可視 r, i, z バンド三波長同時偏光撮像装置 MuSaSHI(Multi-wavelength SimultaneouS High throughput Imager and polarimeter; Oasa et al. 2020) をぐんま天文台 150cm 望遠鏡 (Hashimoto et al. 2002) に搭載して観測を実施し た。第一段階として 150cm 望遠鏡ベントカセグレン焦点 (F12.2) に MuSaSHI を直接搭載するマウントを製作 し、 150cm 望遠鏡として初めての r, i, z バンドの多色同時撮像観測に成功した。しかし、視野が 2 ′ .6 × 2 ′ .5 と狭く、ピクセルスケールが 0 ′′ .147 pixel −1 と典型的なシーイングに比べて過度なオーバーサンプリング で、限界等級や測光精度に問題があり、装置を搭載する際の位置の再現性や運用効率、望遠鏡制御系との 連携などにも課題があることが判明した。そこで、観測視野を拡大し測光精度の向上を図るべく、 SaCRA 望遠鏡 (F6.5) 用に開発された MuSaSHI の光学設計に可能な限り近づけるためのレデューサーの開発を行な い、観測環境の改善を図った。 レデューサー光学系は 2 枚の市販レンズを用いて F12.2 から F6.7 へ変換する設計とし、筐体は軽量かつ 撓みの影響が少ないものとし、位置決めピンを採用することで取り付け / 取り外しの再現性を確保する工 夫を行なった。加えて、望遠鏡制御系との通信環境の充実やコマンドの整備などを実施した。 それらを踏まえて、 150cm 望遠鏡に開発したレデューサーと MuSaSHI を搭載した観測を実施したとこ ろ、光学設計の期待値と同等の 4 ′ .7 × 4 ′ .6, 0 ′′ .27 pixel −1 の観測視野とピクセルスケールが達成され、 SaCRA 望遠鏡 /MuSaSHI での観測結果との比較から、限界等級が r バンドで約 1.5 等深い観測が達成されていること が確認された。その後、ぐんま天文台 150cm 望遠鏡に MuSaSHI を持ち込んだ観測を 2024 年 10 月までに合計 39 夜実施し、継続的な運用を実現している。今後、光学系が最適化されたレデューサーを開発することが できれば、観測精度のさらなる向上が見込まれる。

Abstract：
We have developed a reducer and observation system for the MuSaSHI (Multi-wavelength SimultaneouS High throughput Imager and polarimeter; Oasa et al. 2020) which was originally designed for the SaCRA (Saitama university Common-use telescope for Research of Astronomy) 55 cm telescope, in order to carry out simultaneous multi-wavelength (r-, i-, and z-bands) imaging observations using the Gunma Astronomical Observatory 150 cm telescope. At the beginning of this project, we installed the MuSaSHI directly at the focal point of the 150 cm telescope (F12.2). It was successful to take the r-, i-, and z-bands simultaneously using the 150 cm telescope. There were some difficulties however in the photometric accuracy due to the small field of view (2 ′ .6 × 2 ′ .5) and the oversampling (0 ′′ .147 pixel −1 ) against a typical seeing size. We have thus developed a new focal reducer to obtain relatively wide FoV images and the control system to handle the MuSaSHI efficiently. The new reducer is designed to reduce the focal ratio from F12.2 to F6.7 by two lenses of commercial products and to be light to reduce distortions. Some additional modifications were also introduced as the MuSaSHI and its control system to improve the operational efficiency. We have conducted 39 night multi-color simultaneous observations by the MuSaSHI on the 150 cm telescope with the new focal reducer until Oct 2024. The field of view and pixel scale were measured to be as 4 ′ .7 × 4 ′ .6, 0 ′′ .27 pixel −1 , respectively, as expected by the optical design. The higher photometric precisions and sensitivities (∼ 1.5 mag deeper on r-band) were achieved with 150 cm/MuSaSHI than SaCRA/MuSaSHI. Future improvement could be expected by optimizing the optical designing of the reducer.

　Key words：instrumentation — optical — multi-color photometry
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太陽系外惑星 TrES-3 b の可視光近赤外線トランジット観測
Optical and Near-Infrared Transit Observations of the Exoplanet TrES-3 b
著者：平野 佑弥, 伊藤 洋一
所属： 兵庫県立大学 天文科学センター 西はりま天文台
Authors：Yuya HIRANO, Yoichi ITOH
Affiliation： Nishi-Harima Astronomical Observatory, Center for Astronomy, University of Hyogo, 407–2 Nishigaichi, Sayo-cho, Hyogo 679–5313, Japan
著者の電子メールアドレス: hirano@nhao.jp, yitoh@nhao.jp
Received 2024 October 31; Accepted 2024 December 6

概要：
2023 年 3 月 19 日から 2024 年 8 月 7 日にかけて、太陽系外惑星 TrES-3 b のトランジット観測を可視光および 近赤外線の複数波長で同時に実施した。観測には、西はりま天文台の 2m なゆた望遠鏡に搭載された西は りま赤外線カメラ( NIC )および 60cm 望遠鏡を使用した。観測された主星と惑星の半径比は、 V バンドで 0.152 から 0.161 、 J バンドで 0.151 から 0.162 、 H バンドで 0.155 から 0.159 、 K s バンドで 0.134 から 0.157 までの 範囲であった。観測期間中、トランジットに顕著な波長依存性の変化は見られず、全波長で均一の半径比 が示唆された。 TrES-3 b の大気は膨張しておらず、晴れた大気または雲の存在によるモデルで説明できる。 また TrES-3 b の大気に顕著なレイリー散乱が見られなかったことが確認され、 Mackebrandt et al. (2017) の 観測結果を支持するものとなった。

Abstract：
We conducted simultaneous transit observations of the exoplanet TrES-3 b in multiple optical and near-infrared wavelengths from March 19, 2023 to August 7, 2024. Observations were carried out using the 2 m Nayuta telescope equipped with the Nishiharima Infrared Camera (NIC) and a 60 cm telescope at the Nishi-Harima Astronomical Observatory. The observed planet-to-star radius ratios ranged from 0.152 to 0.161 in the V band, 0.151 to 0.162 in the J band, 0.155 to 0.159 in the H band, and 0.134 to 0.157 in the K s band. Throughout the observation period, no significant wavelength-dependent variations were detected in the radius ratio, suggesting uniformity in the radius ratio across all wavelengths. This indicates that the atmosphere of TrES-3 b is not significantly expanded and can be explained by both clear and cloudy atmospheric models. Additionally, no prominent Rayleigh scattering feature was detected, supporting the findings of Mackebrandt et al. (2017).

　Key words：planets and satellites: atmospheres — techniques: photometric — astrochemistry
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MALLS のエシェルモード導入と初期性能
Installation and initial performance of MALLS echelle mode
著者：本田 敏志1, 古塚 来未1,2, 伊藤 洋一1
所属： 1) 兵庫県立大学 天文科学センター 西はりま天文台
2) 兵庫県立大学 理学研究科
Authors：Satoshi HONDA1, Kurumi FURUTSUKA1,2 Yoichi ITOH1
Affiliation： 1) Nishi-Harima Astronomical Observatory, Center for Astronomy, University of Hyogo, 407–2 Nishigaichi, Sayo-cho, Hyogo 679–5313, Japan
2) Graduate School of Science, University of Hyogo 著者の電子メールアドレス: honda@nhao.jp
Received 2024 November 6; Accepted 2024 December 6

概要：
MALLS (Medium And Low-dispersion Long-slit Spectrograph) は兵庫県立大学西はりま天文台の 2m なゆた 望遠鏡に搭載されているロングスリット分光器で、 3 つの回折格子を切り替えることで低分散 (R (= λ/∆λ) ∼ 600 )から中分散 (R ∼ 10,000) までのモードで分光観測できる装置である。 2018 年にエシェルとクロス ディスパーザをインストールし、エシェルモードでの観測を可能にした。初期のエシェルモードでの性能 ̊ のスペクトルが得られ、効率は中分散 を調査した結果、波長分解能 (R) は約 35,000 、波長域は 4960–6800 A モード (1800 本グレーティング ) の 3 分の 1 程度であることがわかった。これは V < 8 等級の比較的明るい星 の化学組成などの調査に十分な性能である。

Abstract：
MALLS is a spectrograph on the 2m Nayuta telescope at Nishi-Harima Astronomical Observatory in the University of Hyogo. The instrument can perform spectroscopy in the low to medium dispersion mode by switching between three gratings, but in 2018 an echelle and a cross-disperser were installed. Investigations of the performance ̊ in the initial echelle mode showed a wavelength resolution (R) of about 35,000, spectral coverage of 4960-6800 A, and an efficiency of about one-third of that in the medium dispersion mode (1800 mm −1 grating). The performance is sufficient for studying the chemical composition and other properties of relatively bright stars (V < 8).

　Key words：Instrumentation:spectrograph — Nayuta — MALLS Echelle
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Astrometric Search for Open Clusters and Associations around Binaries with Early Type Primaries
Author： Yoichi ITOH
Affiliation：Nishi-Harima Astronomical Observatory, Center for Astronomy, University of Hyogo,407–2 Nishigaichi, Sayo-cho, Hyogo 679–5313, Japan
著者の電子メールアドレス: yitoh@nhao.jp Received 2024 October 31; Accepted 2024 December 10

Abstract：
In this study, we present result of astrometric search for open clusters and associations around an early-type primary star in a binary or multiple star system. Based on the position, parallax, and proper motion measured by Gaia satellite, 98 open clusters and 110 associations were identified. Among them, 109 clusters and associations are newly discovered. The number of the membership ranged from 8 to 1526. The ages of the open clusters and associations were estimated to be between 10 6.3 yr and 10 8.9 yr. It is indicated that most of early-type stars are born in a stellar cluster with a number of low-mass stars. The low-mass stars in the open clusters and associations are candidates of post T Tauri stars.

Key words：open clusters and associations: general — parallaxes — proper motions
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Study of spectral variability by spectroscopic observation of recurrent nova / symbiotic stars T CrB
Author: Kazuko Ando1, Toshimitsu Toda1, Shuichi Nakagawa1 , Syoki Muraoka1, Tomohito Oshima2, Kenta Taguchi3,4, Naoya Fukuda1
Affiliation：
1) Okayama University of Science, 1–1 Ridaicho, Kita-ku, Okayama-shi 700–0005, Japan
2) Nishi-Harima Astronomical Observatory, Center for Astronomy, University of Hyogo, 407–2 Nishigaichi, Sayo-cho, Hyogo 679–5313, Japan
3) Okayama Observatory, Kyoto University, 3037-5 Honjo, Kamogata-cho, Asakuchi, Okayama 719-0232, Japan
4) Department of Astronomy,KyotoUniversity, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606–8502, Japan
著者の電子メールアドレス: Kazuko.ando02@gmail.jp
　Received 2024 October 31; Accepted 2024 December 11

Abstract：
T CrB is a recurrent nova that has attracted attention because of several nova explosions in the past. This object is a binary of a white dwarf and a red giant (M3III), and it is also known that semi-regular variability is observed because the apparent size of the photosphere changes due to the orbital motion (P = 227.55 d) of the binary star. This object was reported to have been in active-state from 2015 to 2023, and began to fade from March 2023. Since T CrB showed the temporary dimming just before previous nova eruption, it might be a sign of the nova eruption, but the nature of this phenomenon is still under discussion. We have performed 14 nights low- resolution spectroscopic observations from April 2016 to May 2019, when it was just in the active-state, and 4 nights spectroscopic observations (including 1 night medium-resolution spectroscopic observations) from February 2023 to July 2024, when it was in the temporary-dimming phase. In this paper, we compare our previous observations with the photometric results of the Kamogata Kiso Kyoto Wide-field survey (KWS) and summarize the spectral variations by different phase.

Key words：nova — symbiotic stars — cataclysmic stars
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