2006ApJ...640..491S

HD 110432 (B1e) has gained considerable recent attention because it is a hard, variable X-ray source with local absorption and also because its optical spectrum is affected by an extensive Be disk. From time-serial echelle data obtained over 2 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 γ Cas and AB Dor, two stars for which it is believed magnetic fields force circumstellar clouds to corotate over the star's surface. The star's optical spectrum also exhibits a number of mainly Fe II and He I 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 9800 K and roughly 3x10²²/cm2, respectively. Its projected disk size covers remarkably large 100 stellar areas, and the emitting volume resides at a surprisingly large distance of 1 AU from the star. 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, even though the rotational velocity is 300-400 km/s. We are unable to find a satisfactory explanation for these extreme line broadenings. Otherwise, HD 110432 and γ Cas share similarly peculiar X-ray and optical characteristics. These include a 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 ``γ Cas analogs.''