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Publication Date

2015

Document Type

Honors Project

Department

Astronomy

Keywords

Stars-Formation, Circumstellar matter, T Tauri stars, Star formation, Circumstellar disks, T Tauri

Abstract

Low excitation forbidden lines of [O I] and [S II] in the spectra of accreting young stars have long been recognized as mass outflow tracers due to their primarily blueshifted emission. The line profiles often possess two kinematic components: a high velocity component (centroids from −30 to −200 km s‾¹) arising in an extended collimated jet, and a low velocity component (centroids from 0 to −10 km s‾¹ ) possibly arising in some form of disk wind. Moreover, a recent paper by Rigliaco et al. (2013) explores the possibility that the low velocity component may itself be comprised of distinct broad and narrow kinematic contributions. Using high-resolution spectra acquired with the Keck I HIRES spectrograph, at a velocity resolution of 6 km s‾¹ , this thesis aims to separate the various kinematic components in T Tauri forbidden lines. Observed profiles from lines of [O I] λ 6300 Å, [O I] λ 5577 Å, and [S II] λλ 6717, 6731 Å are decomposed with Gaussian fits into components that share kinematic features across the multiple lines. For the high velocity components, the relation between mass ejection in the jets and mass accretion rates onto the star, originally found by Hartigan et al. (1995), is re-evaluated. For the low velocity components, we confirm that a combination of broad and narrow components is commonly observed, and that the properties of the narrow components are comparable to those expected from models of X-ray driven photoevaporative flows from the disk.

Language

English

Comments

xii, 141 pages : color illustrations. Honors project-Smith College, 2015. Includes bibliographical references (pages 94-97)

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