Constraining the X-ray luminosities of asymptotic giant branch stars: TX camelopardalis and T cassiopeia

Joel H. Kastner; Noam Soker

doi:10.1086/420877

Constraining the X-ray luminosities of asymptotic giant branch stars: TX camelopardalis and T cassiopeia

Joel H. Kastner^*, Noam Soker

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

13 Scopus citations

Abstract

To probe the magnetic activity levels of asymptotic giant branch (AGB) stars, we used XMM-Newton to search for X-ray emission from two well-studied objects, TX Cam and T Cas. The former star displays polarized maser emission, indicating magnetic field strengths of B ∼ 5 G, and the latter is one of the nearest known AGB stars. Neither star was detected by XMM-Newton. We use the upper limits on EPIC (CCD detector) count rates to constrain the X-ray luminosities of these stars and derive L_X < 10³¹ ergs s^-1 (<10³⁰ ergs s^-1) for an assumed X-ray emission temperature T_X = 3 × 10⁶ K (10⁷ K). These limits represent ≲10% (≲1%) of the X-ray luminosity expected under models in which AGB magnetic fields are global and potentially play an important role in collimating and/or launching AGB winds. We suggest, instead, that the B field strengths inferred from maser observations are representative of localized magnetic clouds.

Original language	English
Pages (from-to)	978-982
Number of pages	5
Journal	Astrophysical Journal
Volume	608
Issue number	2 I
DOIs	https://doi.org/10.1086/420877
State	Published - 20 Jun 2004
Externally published	Yes

Keywords

Stars: AGB and post-AGB
Stars: magnetic fields
Stars: mass loss
Stars: winds, outflows
X-rays: ISM

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@article{8253cc36424f48298fd22620dc6fd466,

title = "Constraining the X-ray luminosities of asymptotic giant branch stars: TX camelopardalis and T cassiopeia",

abstract = "To probe the magnetic activity levels of asymptotic giant branch (AGB) stars, we used XMM-Newton to search for X-ray emission from two well-studied objects, TX Cam and T Cas. The former star displays polarized maser emission, indicating magnetic field strengths of B ∼ 5 G, and the latter is one of the nearest known AGB stars. Neither star was detected by XMM-Newton. We use the upper limits on EPIC (CCD detector) count rates to constrain the X-ray luminosities of these stars and derive LX < 1031 ergs s-1 (<1030 ergs s-1) for an assumed X-ray emission temperature TX = 3 × 106 K (107 K). These limits represent ≲10% (≲1%) of the X-ray luminosity expected under models in which AGB magnetic fields are global and potentially play an important role in collimating and/or launching AGB winds. We suggest, instead, that the B field strengths inferred from maser observations are representative of localized magnetic clouds.",

keywords = "Stars: AGB and post-AGB, Stars: magnetic fields, Stars: mass loss, Stars: winds, outflows, X-rays: ISM",

author = "Kastner, {Joel H.} and Noam Soker",

year = "2004",

month = jun,

day = "20",

doi = "10.1086/420877",

language = "英语",

volume = "608",

pages = "978--982",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "IOP Publishing Ltd.",

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TY - JOUR

T1 - Constraining the X-ray luminosities of asymptotic giant branch stars

T2 - TX camelopardalis and T cassiopeia

AU - Kastner, Joel H.

AU - Soker, Noam

PY - 2004/6/20

Y1 - 2004/6/20

N2 - To probe the magnetic activity levels of asymptotic giant branch (AGB) stars, we used XMM-Newton to search for X-ray emission from two well-studied objects, TX Cam and T Cas. The former star displays polarized maser emission, indicating magnetic field strengths of B ∼ 5 G, and the latter is one of the nearest known AGB stars. Neither star was detected by XMM-Newton. We use the upper limits on EPIC (CCD detector) count rates to constrain the X-ray luminosities of these stars and derive LX < 1031 ergs s-1 (<1030 ergs s-1) for an assumed X-ray emission temperature TX = 3 × 106 K (107 K). These limits represent ≲10% (≲1%) of the X-ray luminosity expected under models in which AGB magnetic fields are global and potentially play an important role in collimating and/or launching AGB winds. We suggest, instead, that the B field strengths inferred from maser observations are representative of localized magnetic clouds.

AB - To probe the magnetic activity levels of asymptotic giant branch (AGB) stars, we used XMM-Newton to search for X-ray emission from two well-studied objects, TX Cam and T Cas. The former star displays polarized maser emission, indicating magnetic field strengths of B ∼ 5 G, and the latter is one of the nearest known AGB stars. Neither star was detected by XMM-Newton. We use the upper limits on EPIC (CCD detector) count rates to constrain the X-ray luminosities of these stars and derive LX < 1031 ergs s-1 (<1030 ergs s-1) for an assumed X-ray emission temperature TX = 3 × 106 K (107 K). These limits represent ≲10% (≲1%) of the X-ray luminosity expected under models in which AGB magnetic fields are global and potentially play an important role in collimating and/or launching AGB winds. We suggest, instead, that the B field strengths inferred from maser observations are representative of localized magnetic clouds.

KW - Stars: AGB and post-AGB

KW - Stars: magnetic fields

KW - Stars: mass loss

KW - Stars: winds, outflows

KW - X-rays: ISM

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U2 - 10.1086/420877

DO - 10.1086/420877

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JO - Astrophysical Journal

JF - Astrophysical Journal

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