Measurement of interstellar extinction for classical T Tauri stars using far-UV H2 line fluxes

Fuente: arXiv
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Main Authors: Fuhrmeister, B., Schneider, P. C., Sperling, Th., France, K., Campbell-White, J., Eislöffel, J.
Format: Preprint
Published: 2024
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author Fuhrmeister, B.
Schneider, P. C.
Sperling, Th.
France, K.
Campbell-White, J.
Eislöffel, J.
author_facet Fuhrmeister, B.
Schneider, P. C.
Sperling, Th.
France, K.
Campbell-White, J.
Eislöffel, J.
contents Understanding the interstellar and potentially circumstellar extinction in the sight lines of classical T Tauri stars is an important ingredient for constructing reliable spectral energy distributions, which catalyze protoplanetary disk chemistry, for example. Therefore, some attempts of measuring $A_{V}$ toward individual stars have been made using partly different wavelength regimes and different underlying assumptions. We used strong lines of Lyα fluorescent H2 and derived the extinction based on the assumption of optically thin transitions. We investigated a sample of 72 classical T Tauri stars observed with the Hubble Space Telescope in the framework of the ULLYSES program. We computed $A_{V}$ and $R_{V}$ values for the 34 objects with sufficient data quality and an additionally $A_{V}$ value for the canonical $R_{V}$ = 3.1 value. Our results agree largely with values obtained from optical data. Moreover, we confirm the degeneracy between $A_{V}$ and $R_{V}$ and present possibilities to break this. Finally, we discuss whether the assumption of optical thin lines is valid.
format Preprint
id arxiv_https___arxiv_org_abs_2411_13247
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Measurement of interstellar extinction for classical T Tauri stars using far-UV H2 line fluxes
Fuhrmeister, B.
Schneider, P. C.
Sperling, Th.
France, K.
Campbell-White, J.
Eislöffel, J.
Solar and Stellar Astrophysics
Astrophysics of Galaxies
Understanding the interstellar and potentially circumstellar extinction in the sight lines of classical T Tauri stars is an important ingredient for constructing reliable spectral energy distributions, which catalyze protoplanetary disk chemistry, for example. Therefore, some attempts of measuring $A_{V}$ toward individual stars have been made using partly different wavelength regimes and different underlying assumptions. We used strong lines of Lyα fluorescent H2 and derived the extinction based on the assumption of optically thin transitions. We investigated a sample of 72 classical T Tauri stars observed with the Hubble Space Telescope in the framework of the ULLYSES program. We computed $A_{V}$ and $R_{V}$ values for the 34 objects with sufficient data quality and an additionally $A_{V}$ value for the canonical $R_{V}$ = 3.1 value. Our results agree largely with values obtained from optical data. Moreover, we confirm the degeneracy between $A_{V}$ and $R_{V}$ and present possibilities to break this. Finally, we discuss whether the assumption of optical thin lines is valid.
title Measurement of interstellar extinction for classical T Tauri stars using far-UV H2 line fluxes
topic Solar and Stellar Astrophysics
Astrophysics of Galaxies
url https://arxiv.org/abs/2411.13247