Doppler imaging of BD+22°4409 (LO Peg) using least-squares deconvolution |
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Authors: | T A Lister A Collier Cameron J Bartus |
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Institution: | School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS; Konkoly Observatory of the Hungarian Academy of Sciences, H‐1525 Budapest, PO Box 67, Hungary |
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Abstract: | We present maximum-entropy reconstructions of the rapidly rotating dwarf single star BD+22°4409 (LO Peg) from observations at the William Herschel Telescope in 1993 August. Since this star is too faint to use the conventional single- or three-line Doppler imaging methods, we make use of the novel method of least-squares deconvolution, which utilizes the large number of photospheric lines in an echelle spectrum to produce a single high signal-to-noise ratio profile. The star-spot distributions from the image reconstructions show cool features at both high and low latitudes, in contradiction to recent theoretical predictions of the dynamo behaviour in rapidly rotating stars. Cross-correlation of the images from consecutive nights shows a good correlation from the small-scale structures, but no evidence of surface differential rotation. From the cross-correlation of the high-latitude spot we are able to reject the period of 9.22 h of Jeffries et al. in favour of their preferred period of 10.17 h, confirming the result of Robb & Cardinal. |
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Keywords: | line: profiles techniques: image processing stars: activity stars: atmospheres stars: individual: BD+22°4409 stars: late-type |
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