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RXJ0806.3+1527: a double degenerate binary with the shortest known orbital period (321s)

G. L. Israel·W. Hummel·S. Covino·S. Campana·I. Appenzeller·W. Gassler·K. -H. Mantel·G. Marconi·C. W. Mauche·U. Munari·I. Negueruela·H. Nicklas·G. Rupprecht·R. L. Smart·O. Stahl·L. Stella
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Abstract

We carried out optical observations of the field of the X-ray pulsator RXJ0806.3+1527. A blue V=21.1 star was found to be the only object consistent with the X-ray position. VLT FORS spectra revealed a blue continuum with no intrinsic absorption lines. Broad (v~1500 km/s), low equivalent width (about -1/-6A) emission lines from the HeII Pickering series were clearly detected. B, V and R time-resolved photometry revealed the presence of about 15% pulsations at the 321s X-ray period, confirming the identification. These findings, together with the period stability and absence of any additional modulation in the 1min-5hr period range, argue in favour of the orbital interpretation of the 321s pulsations. The most likely scenario is thus that RXJ0806.3+1527 is a double degenerate system of the AM CVn class. This would make RXJ0806.3+1527 the shortest orbital period binary currently known and one of the best candidates for gravitational wave detection.

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G. L. Israel, W. Hummel, S. Covino, S. Campana, I. Appenzeller, W. Gassler, K. -H. Mantel, G. Marconi, C. W. Mauche, U. Munari, I. Negueruela, H. Nicklas, G. Rupprecht, R. L. Smart, O. Stahl, L. Stella. 2002-03-04. RXJ0806.3+1527: a double degenerate binary with the shortest known orbital period (321s). https://doi.org/10.1051/0004-6361%3A20020314

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