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文部科学省が推進するGIGAスクール構想の中で教育現場における「講義のオンライン化」は重要な目標課題の一つであったが，新型コロナウイルス感染症（COVID-19）をきっかけに全国の教育機関における講義のオンライン化が急速に進んだ．オンライン化が感染対策として有効である事は疑問の余地はないと思われるが，オンライン配信による遠隔講義が，対面講義と同等の学習効果を生み出しているかどうかについては，これまで十分な客観的検証がされているとはいえない．我々は，無線LAN接続による位置情報とZoom®ログを用いて学生が遠隔講義と対面講義のいずれに出席していたかを推定し，講義形式が学業成績GPAに与える影響を検討した．粗解析では対面講義参加割合が正に学業成績GPAと相関していた．学業成績には前年度の学業成績と入試成績が関与している事が分かったため，これらの因子を調整したところ，低学年では対面講義を志向する群が遠隔講義を志向する群に比して学業成績が良かったが，高学年では両群に統計学的な差は無かった．本分析は，ポストコロナ期の高等教育機関における教育の在り方について議論する貴重な材料になり得ると考えられる．

A line-depth ratio (LDR) of two spectral lines with different excitation potentials is expected to be correlated with the effective temperature ($T_\mathrm{eff}$). It is possible to determine $T_\mathrm{eff}$ of a star with a precision of tens of Kelvin if dozens or hundreds of tight LDR-$T_\mathrm{eff}$ relations can be used. Most of the previous studies on the LDR method were limited to optical wavelengths, but Taniguchi and collaborators reported 81 LDR relations in the $YJ$ band, 0.97-1.32 $��\mathrm{m}$, in 2018. However, with their sample of only 10 giants, it was impossible to account for the effects of surface gravity and metallicity on the LDRs well. Here we investigate the gravity effect based on $YJ$-band spectra of 63 stars including dwarfs, giants, and supergiants observed with the WINERED spectrograph. We found that some LDR-$T_\mathrm{eff}$ relations show clear offsets between the sequence of dwarfs and those of giants/supergiants. The difference between the ionization potentials of the elements considered in each line pair and the corresponding difference in the depths can, at least partly, explain the dependency of the LDR on the surface gravity. In order to expand the stellar parameter ranges that the LDR method can cover with high precision, we obtained new sets of LDR-$T_\mathrm{eff}$ relations for solar-metal G0-K4 dwarfs and F7-K5 supergiants, respectively. The typical precision that can be achieved with our relations is 10-30 K for both dwarfs and supergiants., 12 pages, 7 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society

We propose a study of interstellar molecules with near-infrared (NIR) high-resolution spectroscopy as a science case for the 3.6-m Devasthal Optical Telescope (DOT). In particular, we present the results obtained on-going survey of diffuse interstellar bands (DIBs) in NIR with the newly developed NIR high-resolution spectrograph WINERED, which offers a high sensitivity in the wavelength range of 0.91-1.36 µm. Using the WINERED spectrograph attached to the 1.3-m Araki telescope in Japan, we obtained high-quality spectra of a number of early-type stars in various environments, such as diffuse interstellar clouds, dark clouds and star-forming regions, to investigate the properties of NIR DIBs and constrain their carriers. As a result, we successfully identified about 50 new NIR DIBs, where only five fairly strong DIBs had been identified previously. Also, some properties of DIBs in the NIR are discussed to constrain the carriers of DIBs.

著者人数: 18名, Accepted: 2018-04-30, 資料番号: SA1180044000

The effective temperature, one of the most fundamental atmospheric parameters of a star, can be estimated using various methods, and here we focus on the method using line-depth ratios (LDRs). This method combines low- and high-excitation lines and makes use of relations between LDRs of these line pairs and the effective temperature. It has an advantage, for example, of being minimally affected by interstellar reddening, which changes stellar colours. We report 81 relations between LDRs and the effective temperature established with high-resolution, $��/����\sim 28,000$, spectra of nine G- to M-type giants in Y and J bands. Our analysis gives the first comprehensive set of LDR relations for this wavelength range. The combination of all these relations can be used to determine the effective temperatures of stars that have 3700, 9 pages, 5 figures, 6 tables, accepted for publication in MNRAS

著者人数: 19名, Accepted: 2016-02-23, 資料番号: SA1160007000

WINERED is a newly built high-efficiency (throughput$ > 25-30\%$) and high-resolution spectrograph customized for short NIR bands at 0.9-1.35 ${\rm ��}$m. WINERED is equipped with ambient temperature optics and a cryogenic camera using a 1.7 ${\rm ��}$m cut-off HgCdTe HAWAII-2RG array detector. WINERED has two grating modes: one with a conventional reflective echelle grating (R$\sim$28,300), which covers 0.9-1.35 $��$m simultaneously, the other with ZnSe or ZnS immersion grating (R$\sim$100,000). We have completed the development of WINERED except for the immersion grating, and started engineering and science observations at the Nasmyth platform of the 1.3 m Araki Telescope at Koyama Astronomical Observatory of Kyoto-Sangyo University in Japan. We confirmed that the spectral resolution ($R\sim$ 28,300) and the throughput ($>$ 40\% w/o telescope/atmosphere/array QE) meet our specifications. We measured ambient thermal backgrounds (e.g., 0.06 ${\rm [e^{-}/sec/pixel]}$ at 287 K), which are roughly consistent with that we expected. WINERED is a portable instrument that can be installed at any telescope with Nasmyth focus as a PI-type instrument. If WINERED is installed on a 10 meter telescope, the limiting magnitude is expected to be J=18-19, which can provide high-resolution spectra with high quality even for faint distant objects., 9 pages, 7 figures

著者人数: 20名, Accepted: 2010-10-18, 資料番号: SA1002774000