¹Catholic University of America, 3700 San Martin Dr., Baltimore MD 21218
²South African Astronomical Observatory, P.O. Box 9, Observatory 7935, South Africa

HD 110432 is a hard, variable X-ray source with local absorption due to an extensive circumstellar disk. From time-serial echelle data obtained over two weeks during 2005 January and February, we have discovered several remarkable characteristics in the star's optical spectrum. The line profiles show rapid variations on some nights which can most likely be attributed to irregularly occurring and short-lived migrating subfeatures. Such features have been found in spectra of  Cas and AB Dor, two stars hosting circumstellar clouds that corotate over their surfaces. The star's optical spectrum also exhibits a number of mainly FeII and HeI emission features with double-lobed profiles typical of an optically thin circumstellar disk viewed nearly edge-on. Using spectral synthesis techniques for the January data, we find that its temperature and column density are close to 9,800 K and roughly 3x10²² cm^-2. Its projected disk size covers a remarkably large 100 stellar areas, and the emitting volume resides at a surprisingly large distance of 1 A.U. Surprisingly, we also find that the absorption wings of the strongest optical and UV lines in the spectrum extend to at least ±1000 km s^-1, even though the rotational velocity is 300 – 400 km s^-1. We are unable to find a satisfactory explanation for these extreme line broadenings. Otherwise, HD 110432 and  Cas share similarly peculiar X-ray and optical characteristics. These include as high X-ray temperature, erratic X-ray variability on timescales of a few hours, optical metallic emission lines, and submigrating features in optical line profiles. Because of these similarities, we suggest that HD 110432 is a member of a select new class of " Cas analogs."

Accepted by ApJ, V640 No. 1 (2006 Mar 20)
Preprints from msmith at stsci.edu
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