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

Yasui, Chikako; Hamano, Satoshi; Fukue, Kei; Kondo, Sohei; Sameshima, Hiroaki; Takenaka, Keiichi; Matsunaga, Noriyuki; Ikeda, Yuji; Kawakita, Hideyo; Otsubo, Shogo; Watase, Ayaka; Taniguchi, Daisuke; Mizumoto, Misaki; Izumi, Natsuko; Kobayashi, Naoto

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


Authors

Chikako Yasui

Satoshi Hamano

Kei Fukue

Sohei Kondo

Hiroaki Sameshima

Keiichi Takenaka

Noriyuki Matsunaga

Yuji Ikeda

Hideyo Kawakita

Shogo Otsubo

Ayaka Watase

Daisuke Taniguchi

Natsuko Izumi

Naoto Kobayashi



Abstract

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.

Citation

Yasui, C., Hamano, S., Fukue, K., Kondo, S., Sameshima, H., Takenaka, K., …Kobayashi, N. (2019). Possible Progression of Mass-flow Processes around Young Intermediate-mass Stars Based on High-resolution Near-infrared Spectroscopy. I. Taurus. Astrophysical Journal, 886(2), Article 115. https://doi.org/10.3847/1538-4357/ab45ee

Journal Article Type Article
Acceptance Date Sep 17, 2019
Online Publication Date Nov 27, 2019
Publication Date Dec 1, 2019
Deposit Date Dec 11, 2019
Publicly Available Date Dec 11, 2019
Journal Astrophysical Journal
Print ISSN 0004-637X
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 886
Issue 2
Article Number 115
DOI https://doi.org/10.3847/1538-4357/ab45ee

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