On the Interpretation of Velocity Residuals in Protoplanetary Disks

Fuente: arXiv
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Main Authors: Aizawa, Masataka, Orihara, Ryuta
Format: Preprint
Published: 2025
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author Aizawa, Masataka
Orihara, Ryuta
author_facet Aizawa, Masataka
Orihara, Ryuta
contents We present a first-order analytical model for line-of-sight velocity residuals, defined as the difference between observed velocities and those predicted by a fiducial model, assuming a flared, nearly axisymmetric disk with the perturbations in disk surface height $δh(r)$, inclination $δi(r)$, and position angle $δ\mathrm{PA}(r)$. Introducing projection-deprojection mapping between sky-plane and disk-frame coordinates, we demonstrate that the normalized velocity residuals exhibit Fourier components up to the third harmonic ($\sin3ϕ$ and $\cos3ϕ$). Moreover, we show that the radial profiles of $δh(r)$, $δi(r)$, and $δ\mathrm{PA}(r)$ can be uniquely recovered from the data by solving a linear inverse problem. For comparison, we highlight factors that are not considered in previous models. We also outline how our framework can be extended beyond the first-order residuals and applied to additional observables, such as line intensities and widths.
format Preprint
id arxiv_https___arxiv_org_abs_2507_23287
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On the Interpretation of Velocity Residuals in Protoplanetary Disks
Aizawa, Masataka
Orihara, Ryuta
Earth and Planetary Astrophysics
Solar and Stellar Astrophysics
We present a first-order analytical model for line-of-sight velocity residuals, defined as the difference between observed velocities and those predicted by a fiducial model, assuming a flared, nearly axisymmetric disk with the perturbations in disk surface height $δh(r)$, inclination $δi(r)$, and position angle $δ\mathrm{PA}(r)$. Introducing projection-deprojection mapping between sky-plane and disk-frame coordinates, we demonstrate that the normalized velocity residuals exhibit Fourier components up to the third harmonic ($\sin3ϕ$ and $\cos3ϕ$). Moreover, we show that the radial profiles of $δh(r)$, $δi(r)$, and $δ\mathrm{PA}(r)$ can be uniquely recovered from the data by solving a linear inverse problem. For comparison, we highlight factors that are not considered in previous models. We also outline how our framework can be extended beyond the first-order residuals and applied to additional observables, such as line intensities and widths.
title On the Interpretation of Velocity Residuals in Protoplanetary Disks
topic Earth and Planetary Astrophysics
Solar and Stellar Astrophysics
url https://arxiv.org/abs/2507.23287