Suzaku monitoring of the Wolf-Rayet binary WR 140 around periastron passage: An approach for quantifying the wind parameters

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DOIResolve DOI: http://doi.org/10.1093/pasj/psv099
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TypeArticle
Journal titlePublications of the Astronomical Society of Japan
ISSN0004-6264
Volume67
Issue6
Article number121
Subjecteclipsing binaries; Wolf-Rayet
AbstractSuzaku observations of the Wolf-Rayet (W-R) binary WR 140 (WC7pd+O5.5fc) were made at four different times around periastron passage in 2009 January. The spectra changed in shape and flux with the phase. As periastron approached, the column density of the low-energy absorption increased, which indicates that the emission from the wind-wind collision plasma was absorbed by the dense W-R wind. The spectra can be mostly fitted with two different components: a warm component with kBT = 0.3-0.6 keV and a dominant hot component with kBT ∼ 3 keV. The emission measure of the dominant, hot component is not inversely proportional to the distance between the two stars. This can be explained by the O star wind colliding before it has reached its terminal velocity, leading to a reduction in its wind momentum flux. At phases closer to periastron, we discovered a cool plasma component in a recombining phase, which is less absorbed. This component may be a relic of the wind-wind collision plasma, which was cooled down by radiation, and may represent a transitional stage in dust formation.
Publication date
PublisherOxford University Press
LanguageEnglish
AffiliationNational Research Council Canada; National Science Infrastructure
Peer reviewedYes
NPARC number21277380
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Record identifier96c4da02-73fc-44b6-9e69-a67e6916aa69
Record created2016-03-09
Record modified2016-05-09
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