SDSS J080449.49+161624.8 : a peculiar AM CVn star from a colour-selected sample of candidates
Roelofs, Gijs H. A., Groot, P. J., Steeghs, D., Rau, Arne, de Groot, E., Marsh, T. R., Nelemans, G., Liebert, James W. and Woudt, P. A.. (2009) SDSS J080449.49+161624.8 : a peculiar AM CVn star from a colour-selected sample of candidates. Monthly Notices of the Royal Astronomical Society, Vol.394 (No.1). pp. 367-374. ISSN 0035-8711
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Official URL: http://dx.doi.org/10.1111/j.1365-2966.2008.14288.x
We describe a spectroscopic survey designed to uncover an estimated similar to 40 AM Canum Venaticorum (AM CVn) stars hiding in the photometric data base of the Sloan Digital Sky Survey. We have constructed a relatively small sample of about 1500 candidates based on a colour selection, which should contain the majority of all AM CVn binaries while remaining small enough that spectroscopic identification of the full sample is feasible.
We present the first new AM CVn star discovered using this strategy, SDSS J080449.49+161624.8, the ultracompact binary nature of which is demonstrated using high-time-resolution spectroscopy obtained with the Magellan telescopes at Las Campanas Observatory, Chile. A kinematic 'S-wave' feature is observed on a period P-orb = 44.5 +/- 0.1 min, which we propose is the orbital period, although the present data cannot yet exclude its nearest daily aliases.
The new AM CVn star shows a peculiar spectrum of broad, single-peaked helium emission lines with unusually strong series of ionized helium, reminiscent of the (intermediate) polars among the hydrogen-rich cataclysmic variables. We speculate that SDSS J0804+1616 may be the first magnetic AM CVn star. The accreted material appears to be enriched in nitrogen, to N/O greater than or similar to 10 and N/C > 10 by number, indicating CNO cycle hydrogen burning, but no helium burning, in the prior evolution of the donor star.
|Item Type:||Journal Article|
|Subjects:||Q Science > QB Astronomy|
|Divisions:||Faculty of Science > Physics|
|Library of Congress Subject Headings (LCSH):||Stars -- Catalogs, Double stars|
|Journal or Publication Title:||Monthly Notices of the Royal Astronomical Society|
|Official Date:||21 March 2009|
|Number of Pages:||8|
|Page Range:||pp. 367-374|
|Access rights to Published version:||Restricted or Subscription Access|
|Funder:||Nederlandse Organisatie voor Wetenschappelijk Onderzoek [Netherlands Organisation for Scientific Research] (NWO), Science and Technology Facilities Council (Great Britain) (STFC)|
|Grant number:||680.50.0610 (NWO)|
Adelman-McCarthy J., et al., 2008, ApJS, 175, 297
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