SU Lyn: Diagnosing the Boundary Layer with UV and Hard X-Ray Data

Symbiotic stars in which the symbiotic phenomenon is powered solely by accretion, often at an average rate that is higher than in cataclysmic variable stars, provide an important opportunity to diagnose boundary layers around disk-Accreting white dwarfs. Here, we investigate SU Lyncis (SU Lyn), a re...

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Detalles Bibliográficos
Publicado:	2018
Materias:	binaries: symbiotic stars: individual (SU Lyncis) ultraviolet: stars X-rays: binaries
Acceso en línea:	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0004637X_v864_n1_p_LopesDeOliveira http://hdl.handle.net/20.500.12110/paper_0004637X_v864_n1_p_LopesDeOliveira
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	paper:paper_0004637X_v864_n1_p_LopesDeOliveira
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spelling	paper:paper_0004637X_v864_n1_p_LopesDeOliveira2023-06-08T14:29:21Z SU Lyn: Diagnosing the Boundary Layer with UV and Hard X-Ray Data binaries: symbiotic stars: individual (SU Lyncis) ultraviolet: stars X-rays: binaries Symbiotic stars in which the symbiotic phenomenon is powered solely by accretion, often at an average rate that is higher than in cataclysmic variable stars, provide an important opportunity to diagnose boundary layers around disk-Accreting white dwarfs. Here, we investigate SU Lyncis (SU Lyn), a recently discovered example of a purely accretion-powered symbiotic star, using the first reliable X-ray spectroscopy, obtained with NuSTAR, and ultraviolet (UV) photometry obtained with Swift. SU Lyn has hard, thermal, X-ray emission that is strongly affected by a variable local absorber that has little impact on the UV emission. Its X-ray spectrum is described well using a plasma cooling from kT ≈ 21 keV, with a 3-30 keV luminosity of approximately 4.9 × 1032 erg s-1. The spectrum is also consistent with the presence of reflection with an amplitude of 1.0, although in that case, the best-fit plasma temperature is 20%-25% lower. The UV to X-ray luminosity ratio of SU Lyn changed significantly between 2015 and 2016. We interpret this as a consequence of a drop by almost 90% in the accretion rate. Whereas the UV luminosity of the disk responded linearly, the luminosity of the optically thin (hard X-ray) emission from the boundary layer remained roughly constant because the boundary layer changed from partially optically thick to almost completely optically thin. Under this interpretation, we place a lower limit on the white dwarf mass of 0.7 M o (0.8 M o if we neglect reflection). © 2018. The American Astronomical Society. All rights reserved. 2018 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0004637X_v864_n1_p_LopesDeOliveira http://hdl.handle.net/20.500.12110/paper_0004637X_v864_n1_p_LopesDeOliveira
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	binaries: symbiotic stars: individual (SU Lyncis) ultraviolet: stars X-rays: binaries
spellingShingle	binaries: symbiotic stars: individual (SU Lyncis) ultraviolet: stars X-rays: binaries SU Lyn: Diagnosing the Boundary Layer with UV and Hard X-Ray Data
topic_facet	binaries: symbiotic stars: individual (SU Lyncis) ultraviolet: stars X-rays: binaries
description	Symbiotic stars in which the symbiotic phenomenon is powered solely by accretion, often at an average rate that is higher than in cataclysmic variable stars, provide an important opportunity to diagnose boundary layers around disk-Accreting white dwarfs. Here, we investigate SU Lyncis (SU Lyn), a recently discovered example of a purely accretion-powered symbiotic star, using the first reliable X-ray spectroscopy, obtained with NuSTAR, and ultraviolet (UV) photometry obtained with Swift. SU Lyn has hard, thermal, X-ray emission that is strongly affected by a variable local absorber that has little impact on the UV emission. Its X-ray spectrum is described well using a plasma cooling from kT ≈ 21 keV, with a 3-30 keV luminosity of approximately 4.9 × 1032 erg s-1. The spectrum is also consistent with the presence of reflection with an amplitude of 1.0, although in that case, the best-fit plasma temperature is 20%-25% lower. The UV to X-ray luminosity ratio of SU Lyn changed significantly between 2015 and 2016. We interpret this as a consequence of a drop by almost 90% in the accretion rate. Whereas the UV luminosity of the disk responded linearly, the luminosity of the optically thin (hard X-ray) emission from the boundary layer remained roughly constant because the boundary layer changed from partially optically thick to almost completely optically thin. Under this interpretation, we place a lower limit on the white dwarf mass of 0.7 M o (0.8 M o if we neglect reflection). © 2018. The American Astronomical Society. All rights reserved.
title	SU Lyn: Diagnosing the Boundary Layer with UV and Hard X-Ray Data
title_short	SU Lyn: Diagnosing the Boundary Layer with UV and Hard X-Ray Data
title_full	SU Lyn: Diagnosing the Boundary Layer with UV and Hard X-Ray Data
title_fullStr	SU Lyn: Diagnosing the Boundary Layer with UV and Hard X-Ray Data
title_full_unstemmed	SU Lyn: Diagnosing the Boundary Layer with UV and Hard X-Ray Data
title_sort	su lyn: diagnosing the boundary layer with uv and hard x-ray data
publishDate	2018
url	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0004637X_v864_n1_p_LopesDeOliveira http://hdl.handle.net/20.500.12110/paper_0004637X_v864_n1_p_LopesDeOliveira
_version_	1768542201706446848

SU Lyn: Diagnosing the Boundary Layer with UV and Hard X-Ray Data

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