X-ray determination of the variable rate of mass accretion onto TW hydrae

Diagnostics of electron temperature (Te), electron density (ne), and hydrogen column density (N H) from the Chandra High Energy Transmission Grating spectrum of He-like Ne IX in TW Hydrae (TW Hya), in conjunction with a classical accretion model, allow us to infer the accretion rate onto the star di...

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Detalles Bibliográficos
Publicado: 2012
Materias:
accretion, accretion disks
stars: formation
stars: individual (TW Hydrae)
techniques: spectroscopic
X-rays: stars
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_20418205_v760_n2_p_Brickhouse
http://hdl.handle.net/20.500.12110/paper_20418205_v760_n2_p_Brickhouse
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_20418205_v760_n2_p_Brickhouse
record_format dspace
spelling paper:paper_20418205_v760_n2_p_Brickhouse2023-06-08T16:33:16Z X-ray determination of the variable rate of mass accretion onto TW hydrae accretion, accretion disks stars: formation stars: individual (TW Hydrae) techniques: spectroscopic X-rays: stars Diagnostics of electron temperature (Te), electron density (ne), and hydrogen column density (N H) from the Chandra High Energy Transmission Grating spectrum of He-like Ne IX in TW Hydrae (TW Hya), in conjunction with a classical accretion model, allow us to infer the accretion rate onto the star directly from measurements of the accreting material. The new method introduces the use of the absorption of Ne IX lines as a measure of the column density of the intervening, accreting material. On average, the derived mass accretion rate for TW Hya is 1.5 × 10 -9 M ⊙yr-1, for a stellar magnetic field strength of 600G and a filling factor of 3.5%. Three individual Chandra exposures show statistically significant differences in the Ne IX line ratios, indicating changes in N H, Te , and ne by factors of 0.28, 1.6, and 1.3, respectively. In exposures separated by 2.7days, the observations reported here suggest a five-fold reduction in the accretion rate. This powerful new technique promises to substantially improve our understanding of the accretion process in young stars. © 2012. The American Astronomical Society. All rights reserved. 2012 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_20418205_v760_n2_p_Brickhouse http://hdl.handle.net/20.500.12110/paper_20418205_v760_n2_p_Brickhouse
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic accretion, accretion disks
stars: formation
stars: individual (TW Hydrae)
techniques: spectroscopic
X-rays: stars
spellingShingle accretion, accretion disks
stars: formation
stars: individual (TW Hydrae)
techniques: spectroscopic
X-rays: stars
X-ray determination of the variable rate of mass accretion onto TW hydrae
topic_facet accretion, accretion disks
stars: formation
stars: individual (TW Hydrae)
techniques: spectroscopic
X-rays: stars
description Diagnostics of electron temperature (Te), electron density (ne), and hydrogen column density (N H) from the Chandra High Energy Transmission Grating spectrum of He-like Ne IX in TW Hydrae (TW Hya), in conjunction with a classical accretion model, allow us to infer the accretion rate onto the star directly from measurements of the accreting material. The new method introduces the use of the absorption of Ne IX lines as a measure of the column density of the intervening, accreting material. On average, the derived mass accretion rate for TW Hya is 1.5 × 10 -9 M ⊙yr-1, for a stellar magnetic field strength of 600G and a filling factor of 3.5%. Three individual Chandra exposures show statistically significant differences in the Ne IX line ratios, indicating changes in N H, Te , and ne by factors of 0.28, 1.6, and 1.3, respectively. In exposures separated by 2.7days, the observations reported here suggest a five-fold reduction in the accretion rate. This powerful new technique promises to substantially improve our understanding of the accretion process in young stars. © 2012. The American Astronomical Society. All rights reserved.
title X-ray determination of the variable rate of mass accretion onto TW hydrae
title_short X-ray determination of the variable rate of mass accretion onto TW hydrae
title_full X-ray determination of the variable rate of mass accretion onto TW hydrae
title_fullStr X-ray determination of the variable rate of mass accretion onto TW hydrae
title_full_unstemmed X-ray determination of the variable rate of mass accretion onto TW hydrae
title_sort x-ray determination of the variable rate of mass accretion onto tw hydrae
publishDate 2012
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_20418205_v760_n2_p_Brickhouse
http://hdl.handle.net/20.500.12110/paper_20418205_v760_n2_p_Brickhouse
_version_ 1768545623536041984

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