TY - JOUR
T1 - X-rays from the mira AB binary system
AU - Kastner, Joel H.
AU - Soker, Noam
N1 - Copyright:
Copyright 2015 Elsevier B.V., All rights reserved.
PY - 2004/12/1
Y1 - 2004/12/1
N2 - We present the results of XMM-Newton X-ray observations of the Mira AB binary system, which consists of a pulsating, asymptotic giant branch primary and nearby (∼0.′6 separation) secondary of uncertain nature. The European Photon Imaging Camera (EPIC) CCD (MOS and pn) X-ray spectra of Mira AB are relatively soft, peaking at ∼1 keV, with only very weak emission at energies >3 keV; lines of Ne IX, Ne X, and O VIII are apparent. Spectral modeling indicates a characteristic temperature TX ∼107 K and intrinsic luminosity LX ∼5 × 1029 ergs s -1 and suggests enhanced abundances of O and, possibly, Ne and Si in the X-ray-emitting plasma. Overall, the X-ray spectrum and luminosity of the Mira AB system more closely resemble those of late-type, pre-main-sequence stars or late-type, magnetically active main-sequence stars than those of accreting white dwarfs. We conclude that Mira B is most likely a late-type, magnetically active, main-sequence dwarf, and X-rays from the Mira AB system arise either from magnetospheric accretion of wind material from Mira A onto Mira B or from coronal activity associated with Mira B itself as a consequence of accretion-driven spin-up. In addition, one (or both) of these mechanisms could be responsible for the recently discovered, pointlike X-ray sources within planetary nebulae.
AB - We present the results of XMM-Newton X-ray observations of the Mira AB binary system, which consists of a pulsating, asymptotic giant branch primary and nearby (∼0.′6 separation) secondary of uncertain nature. The European Photon Imaging Camera (EPIC) CCD (MOS and pn) X-ray spectra of Mira AB are relatively soft, peaking at ∼1 keV, with only very weak emission at energies >3 keV; lines of Ne IX, Ne X, and O VIII are apparent. Spectral modeling indicates a characteristic temperature TX ∼107 K and intrinsic luminosity LX ∼5 × 1029 ergs s -1 and suggests enhanced abundances of O and, possibly, Ne and Si in the X-ray-emitting plasma. Overall, the X-ray spectrum and luminosity of the Mira AB system more closely resemble those of late-type, pre-main-sequence stars or late-type, magnetically active main-sequence stars than those of accreting white dwarfs. We conclude that Mira B is most likely a late-type, magnetically active, main-sequence dwarf, and X-rays from the Mira AB system arise either from magnetospheric accretion of wind material from Mira A onto Mira B or from coronal activity associated with Mira B itself as a consequence of accretion-driven spin-up. In addition, one (or both) of these mechanisms could be responsible for the recently discovered, pointlike X-ray sources within planetary nebulae.
KW - Stars: AGB and post-AGB
KW - Stars: magnetic fields
KW - Stars: mass loss
KW - Stars: winds, outflows
KW - X-rays: ISM
UR - http://www.scopus.com/inward/record.url?scp=11144255073&partnerID=8YFLogxK
U2 - 10.1086/424921
DO - 10.1086/424921
M3 - 文章
AN - SCOPUS:11144255073
VL - 616
SP - 1188
EP - 1192
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 2 I
ER -