▁from ▁a ▁high ▁exc itation ▁component ▁in ▁the ▁spectrum ▁and ▁from ▁radial ▁velocity ▁variations , ▁but ▁the ▁orbit ▁is ▁unknown . ▁ ▁U ▁Lac ert ae ▁is ▁a ▁variable ▁star ▁class ified ▁as ▁a ▁sem ire g ular ▁variable . ▁The ▁period icity ▁is ▁uncertain ▁but ▁a ▁main ▁period ▁of ▁ 1 5 0 ▁days ▁and ▁a ▁long ▁secondary ▁period ▁of ▁ 5 5 0 ▁– ▁ 6 9 0 ▁days ▁have ▁been ▁suggested . ▁A ▁study ▁of ▁Hi pp ar cos ▁satellite ▁phot ometry ▁found ▁an ▁amplitude ▁of ▁ 0 . 7 7 ▁magn itudes ▁and ▁found ▁no ▁period icity . ▁ ▁The ▁General ▁Catalogue ▁of ▁Variable ▁Stars ▁lists ▁an ▁amplitude ▁of ▁ 2 . 7 ▁magn itudes . ▁ ▁Water ▁mas ers ▁have ▁been ▁detected ▁around ▁U ▁Lac ert ae , ▁common ▁in ▁the ▁extended ▁atmos pher es ▁of ▁very ▁l umin ous ▁cool ▁stars . ▁ ▁See ▁also ▁▁ ▁List ▁of ▁largest ▁stars ▁ ▁References ▁ ▁Notes ▁ ▁Category : M - type ▁super gi ants ▁Category : L ac erta ▁( const ell ation ) ▁Lac ert ae , ▁U ▁ 2 1 5 9 2 4 ▁ 1 1 2 5 4 5 ▁Category : D urch m uster ung ▁objects ▁Category : 2 MA SS ▁objects ▁Category : Sem ire g ular ▁variable ▁stars ▁Category : Em ission - line ▁stars <0x0A> </s> ▁M uge o - d ong ▁is ▁a ▁d ong , ▁or ▁neighborhood , ▁of ▁Nam - gu ▁in ▁U ls an , ▁South