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The long period intermediate polar 1RXS J154814.5-452845

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De Martino, Domitilla, Bonnet-Bidaud, Jean-Marc, Mouchet, M., Gaensicke, B. T. (Boris T.), Haberl, F. and Motch, C.. (2006) The long period intermediate polar 1RXS J154814.5-452845. Astronomy & Astrophysics, Vol.449 (No.3). pp. 1151-1160. ISSN 0004-6361

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Official URL: http://dx.doi.org/10.1051/0004-6361:20053877

Abstract

We present the first time resolved medium resolution optical spectroscopy of the recently identified peculiar Intermediate Polar (IP)1RXS J154814.5-452845, which allows us to precisely determine the binary orbital period (P Ω = 9.87 ± 0.03 h) and the white dwarf spin period (P ω = 693.01
± 0.06 s). This system is then the third just outside the purported ∼6–10 h IP orbital period gap and the fifth of the small group of long period IPs, which has a relatively high degree of asynchronism. From the presence of weak red absorption features, we identify the secondary star with a spectral type K2 ± 2 V, which appears to have evolved on the nuclear timescale. From the orbital radial velocities of
emission and the red absorption lines a mass ratio q = 0.65
± 0.12 is found. The masses of the components are estimated to be M WD ≥ 0.5 M and M sec = 0.4−0.79 M and the binary inclination 25 ◦ < i ≤ 58 ◦ . A distance between 540–840 pc is estimated. At this distance, the presence of peculiar absorption features surrounding Balmer emissions cannot be due to the contribution of the white dwarf photosphere and their spin modulation suggests an origin in the magnetically confined accretion flow. The white dwarf is also not accreting at a particularly high rate(. M < 5 × 10
16 g s −1 ), for its orbital period. The spin-to-orbit period ratio P ω /P Ω = 0.02 and the low mass accretion rate suggest that this system is far from spin equilibrium. The magnetic moment of the accreting white dwarf is found to be µ < 4.1 × 10 32 G cm 3, indicating a low magnetic
field system.

Item Type:

Journal Article

Subjects:

Q Science > QB Astronomy

Divisions:

Faculty of Science > Physics

Library of Congress Subject Headings (LCSH):

Cataclysmic variable stars, X-ray sources, Galactic, Accretion (Astrophysics), Stars -- Magnetic fields

Journal or Publication Title:

Astronomy & Astrophysics

Publisher:

EDP Sciences

ISSN:

0004-6361

Official Date:

April 2006

Dates:

Date	Event
April 2006	Published

Volume:

Vol.449

Number:

No.3

Page Range:

pp. 1151-1160

Identification Number:

10.1051/0004-6361:20053877

Status:

Peer Reviewed

Access rights to Published version:

Open Access

Funder:

Italy. Ministero dell'istruzione, dell'università e della ricerca (MIUR), Particle Physics and Astronomy Research Council (Great Britain) (PPARC)

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