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| Paper: |
Spectral Analysis and Constraints on the Nature of the Ultra-Compact Binary RXJ0806.3+1527 |
| Volume: |
372, 15th European Workshop on White Dwarfs |
| Page: |
419 |
| Authors: |
Reinsch, K.; Steiper, J.; Dreizler, S. |
| Abstract: |
RX J0806.3+1527 has been discovered as a luminous soft X-ray source during the ROSAT All-Sky Survey and is suspected to be a double-degenerate white dwarf binary with the shortest known orbital period of 321 s. We have performed the first NLTE analysis of its optical spectrum which consists of a blue continuum with weak emission lines superimposed. Using a grid of hot white dwarf atmospheres including illumination effects we have derived an abundance ratio (He/H) ≈ 0.1 (by number) and a comparably low surface gravity log g = 6 of the irradiated system component. The observed flux implies a distance d ≈ 2.0 kpc to the system. Our findings provide new constrains for the different models proposed for the nature of this peculiar binary. The donor must have about solar composition. If line emission arises from its irradiated side it could be either a low-mass white dwarf or a substellar object. Alternatively, line emission could arise from an accretion column standing several white dwarf radii above the photosphere of the accretor. Such conditions are encountered in systems with comparably low field strengths and high mass-flow rates. |
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