Youthful Exuberance of FU Ori Accretion Disks

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Abstract/Contents

Abstract: FU Ori objects are a class of young stellar object (YSO) currently seen in an outburst state. It is generally accepted that the outbursts are caused by the onset of rapid accretion at rates three to four orders of magnitude larger than those of quiescent-state young T Tauri stars. During the ensuing decades- to century-long outbursts, the accretion disks outshine their central stars by factors of 100-1000, leading to models of the outburst radiation as being purely due to a rotating disk. About half of the known FU Ori objects were detected during this sudden transition from quiescence to outburst via optical/infrared brightness increases on the order of four to five magnitudes. We present new optical and near-infrared observations of the newest confirmed FU Ori objects, HBC 722 and Gaia 17bpi, and discuss the successes and limitations of the conventional model. This model is a thin Keplerian disk featuring a modified Shakura-Sunyaev temperature profile, with each annulus radiating as an area-weighted spectrum given by a NextGen atmosphere at the appropriate temperature. We consider the overall spectral energy distribution (SED) as well as medium-resolution spectra in evaluating best-fit models to the data. Both sources have lower luminosity than previously studied FU Ori-type outbursts, and correspondingly are fit by lower accretion rate disks.

Author	Rodriguez, Antonio C.
Degree granting institution	Stanford University, Department of Physics
Thesis advisor	Hillenbrand, Lynne A.
Thesis advisor	Romani, Roger W.
Thesis advisor	Macintosh, Bruce

Location	https://purl.stanford.edu/ch079dv9501

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License: This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).

Preferred citation: Rodriguez, Antonio C. (2020). Youthful Exuberance of FU Ori Accretion Disks. Stanford Digital Repository. Available at: https://purl.stanford.edu/ch079dv9501

Undergraduate Theses, Department of Physics

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