Possible Progression of Mass-flow Processes around Young Intermediate-mass Stars Based on High-resolution Near-infrared Spectroscopy. I. Taurus

We used the WINERED spectrograph to perform near-infrared high-resolution spectroscopy (resolving power R = 28,000) of 13 young intermediate-mass stars in the Taurus star-forming region. Based on the presence of near- and mid-infrared continuum emission, young intermediate-mass stars can be classified into three different evolutionary stages: Phases I, II, and III in the order of evolution. Our obtained spectra (λ = 0.91–1.35 μm) depict He i λ10830 and Pβ lines that are sensitive to magnetospheric accretion and winds. We also investigate five sources each for Pβ and He i lines that were obtained from previous studies along with our targets. We observe that the Pβ profile morphologies in Phases I and II corresponded to an extensive variety of emission features; however, these features are not detected in Phase III. We also observe that the He i profile morphologies are mostly broad subcontinuum absorption lines in Phase I, narrow subcontinuum absorption lines in Phase II, and centered subcontinuum absorption features in Phase III. Our results indicate that the profile morphologies exhibit a progression of the dominant mass-flow processes: stellar wind and probably magnetospheric accretion in the very early stage, magnetospheric accretion and disk wind in the subsequent stage, and no activities in the final stage. These interpretations further suggest that opacity in protoplanetary disks plays an important role in mass-flow processes. Results also indicate that He i absorption features in Phase III sources, associated with chromospheric activities even in such young phases, are characteristics of intermediate-mass stars

First Detection of A–X (0,0) Bands of Interstellar C2 and CN

We report the first detection of C2 P - S +A Xu g 11 (0,0) and CN P - S +A Xu 22 (0,0) absorption bands in the interstellar medium. The detection was made using the near-infrared (0.91–1.35μm) high-resolution (R=20,000 and 68,000) spectra of Cygnus OB2 No. 12 collected with the WINERED spectrograph mounted on the 1.3m Araki telescope. The A–X (1,0) bands of C2 and CN were detected simultaneously. These near-infrared bands have larger oscillator strengths, compared with the A–X (2,0) bands of C2 and CN in the optical. In the spectrum of the C2 (0,0) band with R=68,000, three velocity components in the line of sight could be resolved and the lines were detected up to high rotational levels (J″∼20). By analyzing the rotational distribution of C2, we could estimate the kinetic temperature and gas density of the clouds with high accuracy. Furthermore, we marginally detected weak lines of 12C13C for the first time in the interstellar medium. Assuming that the rotational distribution and the oscillator strengths of the relevant transitions of 12C2 and 12C13C are the same, the carbon isotope ratio was estimated to be 12C/13C=50–100, which is consistent with the ratio in the local interstellar medium. We also constrained the oscillator strength ratio of the C2 (0,0) and (1,0) bands, for which there exists a discrepancy between theoretical calculations and experimental results. This unique constraint obtained from astronomical observation will contribute to improving the accuracy of the oscillator strength measurement, which will lead to further advancements of the C2 excitation model and allow the physical conditions of clouds to be derived

WINERED High-resolution Near-infrared Line Catalog: A-type Star

We present a catalog of absorption lines in the z', Y, and J bands that we identified in 21 Lyn, a slowly rotating A0.5 V star. We detected 155 absorption features in the high-resolution (0.90–1.35 μm, R = 28,000) spectrum obtained with the WINERED spectrograph after the telluric absorption was carefully removed using a spectrum of a B-type star as a telluric standard. With a visual comparison with synthetic spectra, we compiled a catalog of 219 atomic lines for the 155 features, some of which are composed of multiple fine structure lines. The high-quality WINERED spectrum enabled us to detect a large number of weak lines down to ~1% in depth, which are identified for an A-type star for the first time. The catalog includes the lines of H, C, N, O, Mg, Al, Si, S, Ca, Fe, and Sr. These new lines are expected to be useful for spectral classification and chemical abundance analyses, while the line catalog is useful for observers who plan to use A-type stars as telluric standards because it is necessary to distinguish between stellar lines and telluric absorption lines in high-resolution spectra. ASCII versions of the spectra are available in the online version of the journal

Fe i Lines in 0.91–1.33 μm Spectra of Red Giants for Measuring the Microturbulence and Metallicities

For a detailed analysis of stellar chemical abundances, high-resolution spectra in the optical have mainly been used, while the development of near-infrared (NIR) spectrograph has opened new wavelength windows. Red giants have a large number of resolved absorption lines in both the optical and NIR wavelengths, but the characteristics of the lines in different wave passbands are not necessarily the same. We present a selection of Fe I lines in the z′, Y, and J bands (0.91–1.33 μm). On the basis of two different lists of lines in this range, the Vienna Atomic Line Database (VALD) and the catalog published by Meléndez & Barbuy in 1999 (MB99), we selected sufficiently strong lines that are not severely blended and compiled lists with 107 Fe I lines in total (97 and 75 lines from VALD and MB99, respectively). Combining our lists with high-resolution (λ/Δλ=28,000) and high signal-tonoise (>500) spectra taken with an NIR spectrograph, WINERED, we present measurements of the iron abundances of two prototype red giants: Arcturus and μLeo. A bootstrap method for determining the microturbulence and abundance together with their errors is demonstrated. The standard deviations of log Fe values from individual Fe I lines are significantly smaller when we use the lines from MB99 instead of those from VALD. With the MB99 list, we obtained x = 1.20 0.11 km s-1 and log Fe = 7.01 0.05 dex for Arcturus, and x = 1.54 0.17 km s-1 and log Fe = 7.73 0.07 dex for μLeo. These final values show better agreements with previous values in the literature than the corresponding values we obtained with VALD

Longitudinal long COVID symptoms in Japanese patients after COVID-19 vaccinations

We conducted a subgroup analysis of a study on the long-term effects of COVID-19 (long COVID) in Japan to assess the effect of vaccination on long COVID symptoms. We assessed the clinical course of 111 patients with long COVID at the time of vaccination. The follow-up period was one year from the onset of COVID-19 or until the administration of the third vaccine dose. Of the 111 patients, 15 (13.5%) reported improvement, four (3.6%) reported deterioration, and 92 (82.9%) reported no change in their long COVID symptoms after vaccination. The most common long COVID symptoms before vaccination were alopecia, dyspnea, muscle weakness, fatigue, and headache among participants whose symptoms improved. Reduced dyspnea and alopecia were the most frequently reported improvements in symptoms after vaccination. Some symptoms persisted, including sleep disturbance, myalgia, and hypersensitivity. Vaccination did not appear to have a clinically important effect on patients with long COVID symptoms