仙(xian)后(hou)座(zuo)PZ是(shi)一(yi)顆(ke)(ke)紅超巨星(xing)(xing),其(qi)(qi)恒(heng)星(xing)(xing)光(guang)(guang)譜分類(lei)為(wei)M3Iab,位(wei)于赫羅圖(tu)的(de)(de)(de)(de)右上(shang)方。這(zhe)代表這(zhe)顆(ke)(ke)恒(heng)星(xing)(xing)的(de)(de)(de)(de)亮度(du)極(ji)高(gao),但有效溫(wen)度(du)卻相對(dui)較低(di)。天文(wen)學家估算這(zhe)顆(ke)(ke)恒(heng)星(xing)(xing)的(de)(de)(de)(de)半(ban)徑為(wei)太(tai)(tai)陽(yang)(yang)半(ban)徑的(de)(de)(de)(de)1,190–1,940倍(bei)。雖然這(zhe)顆(ke)(ke)恒(heng)星(xing)(xing)的(de)(de)(de)(de)體積(ji)比太(tai)(tai)陽(yang)(yang)大十(shi)億倍(bei),但其(qi)(qi)質(zhi)量(liang)僅(jin)僅(jin)約為(wei)太(tai)(tai)陽(yang)(yang)質(zhi)量(liang)的(de)(de)(de)(de)數(shu)十(shi)倍(bei)。這(zhe)顆(ke)(ke)恒(heng)星(xing)(xing)不單是(shi)其(qi)(qi)中(zhong)一(yi)個體積(ji)最(zui)大的(de)(de)(de)(de)恒(heng)星(xing)(xing),亦是(shi)紅超巨星(xing)(xing)中(zhong)最(zui)明(ming)亮的(de)(de)(de)(de)恒(heng)星(xing)(xing)之(zhi)一(yi)。其(qi)(qi)亮度(du)約為(wei)太(tai)(tai)陽(yang)(yang)的(de)(de)(de)(de)數(shu)十(shi)萬倍(bei),是(shi)其(qi)(qi)中(zhong)一(yi)個最(zui)明(ming)亮的(de)(de)(de)(de)恒(heng)星(xing)(xing)。仙(xian)后(hou)座(zuo)PZ也(ye)是(shi)一(yi)顆(ke)(ke)半(ban)規則變星(xing)(xing),其(qi)(qi)變光(guang)(guang)周(zhou)期約為(wei)925日(ri)。
盡管這(zhe)顆(ke)(ke)恒(heng)星非常(chang)明亮,但它距離地球約17800光年(5460秒差(cha)距),因此在夜空中較為暗淡。這(zhe)顆(ke)(ke)恒(heng)星的(de)視星等為8.75等,代表(biao)人類肉眼無法(fa)看到(dao)這(zhe)顆(ke)(ke)恒(heng)星,需(xu)要依靠望遠鏡才能看到(dao)。
仙(xian)后座(zuo)PZ是其(qi)中(zhong)一顆人(ren)類已知(zhi)體積最(zui)大的恒星。天(tian)(tian)(tian)文學家估計,其(qi)半(ban)徑為太(tai)(tai)陽半(ban)徑的1,190–1,940倍(bei)(5.53到9.02天(tian)(tian)(tian)文單(dan)位),即827,645,000至1,349,270,000公(gong)(gong)里。若把仙(xian)后座(zuo)PZ置于(yu)太(tai)(tai)陽系中(zhong)心,那(nei)么其(qi)表面將超(chao)過木星的軌(gui)(gui)道(dao)(dao)(5.204267天(tian)(tian)(tian)文單(dan)位,778,547,200公(gong)(gong)里),直迫土星軌(gui)(gui)道(dao)(dao)(9.5820172天(tian)(tian)(tian)文單(dan)位,1,433,449,370公(gong)(gong)里)。光繞(rao)(rao)這顆恒星一周需時4.82至7.85小時,而(er)光環繞(rao)(rao)太(tai)(tai)陽赤道(dao)(dao)一周僅需時14.5秒。
仙后座PZ的(de)大小(xiao)可(ke)能被(bei)高(gao)估,因(yin)為(wei)其不尋常的(de)K頻和(he)人(ren)為(wei)的(de)發紅校正(zheng)錯(cuo)誤。而它(ta)亦可(ke)能被(bei)低估,因(yin)為(wei)科學家是以同類恒星作比較得出(chu)其大小(xiao)的(de)。