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Paper: Evidence of Asymmetries in the Aldebaran Photosphere from Multi-Wavelength Lunar Occultations
Volume: 510, Stars: From Collapse to Collapse
Page: 211
Authors: Dyachenko, V.; Richichi, A.; Pandey, A.; Sharma, S.; Tasuya, O.; Balega, Yu.; Beskakotov, A.; Rastegaev, D.
Abstract: We present the results of three lunar occultations of the K5 giant Aldebaran, observed in late 2015 and early 2016. The 6-m SAO, 1.3-m Devasthal, and 2.4-m TNT telescopes were used to obtain light curves with few ms sampling and at wavelengths ranging from the ultraviolet to the red. These were fitted using uniform-disk (UD) models and then converted to limb-darkened (LD) models using Kurucz's atmospheric models. The resulting diameter values are in good agreement with previous determinations, with an average LD diameter of 20.3 milliseconds of arc. We have also been able to use model-independent methods to reconstruct the star's brightness profile and have found indications that the photospheric brightness profile of Aldebaran may not have been symmetric, a finding already reported by other authors for this and for similar late-type stars. The presence of surface spots on a scale of a few milliarcseconds is a likely explanation of the observed asymmetries.
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