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Long-perio d magneti c variabilit y o f H D 999 6
V.D . Bychkov , E . Gerth , R . Kroll , V.G . Shtol'
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Specia l Astrophysica l Observator y o f th e Russia n AS , Nizhni j Arkhy z 357147 , Russi a Centra l Institut e o f Astrophysics , Telegrafenber g D -- 01561 , German y Institut o d e Astrofisic a d e Canarias , L a Laguna , Tenerife , Spai n

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Abstract . A stud y o f magneti c behaviou r o f th e long-tim e perio d o f th e sta r H D 999 6 i s bein g continued . Th e obtaine d magneti c measurement s allowe d u s t o refin e th e perio d o f "secula r variability " -- 21. 5 yrs . Th e sta r H D 999 6 (H R 465 , G Y And ) i s know n a s on e o f th e long-perio d A p stars . Compilatio n o f photometri c measurement s for th e sta r mad e i t possibl e t o establis h tha t it s perio d range s fro m 7750 t o 8550 days , i.e. abou t 2 0 years . Magneti c field measurement s o f H D 999 6 wer e initiate d b y Babcoc k (1958 ) the n continue d b y Presto n & Wolff (1970) , Scholz (1978 ; 1983) . 4 9 photographi c estimate s hav e bee n mad e for nearl y 3 4 years . Wit h th e ai m o f specifyin g th e magneti c behaviou r o f thi s object , i n th e frame s o f investigatio n o f th e magneti c behaviou r o f A p star s i n th e Specia l Astrophysica l Observatory , Nizhni j Arkhyz , magneti c measurement s a t th e 6 m telescop e usin g th e hydrogen-lin e magnetomete r (Shtol' , 1991 ; 1993) hav e bee n started . W e presen t th e obtaine d dat a for H D 9996 i n Tabl e 1 . Thank s t o ou r dat a th e tim e o f magneti c monitorin g ha s increase d t o 4 8 years . I n Fig. l w e sho w all magneti c field measurement s a s accordin g t o time . I t i s seen from th e figure ho w widel y varie s th e tim e betwee n measurements , whic h make s i t difficult t o analyz e th e variability . Usin g th e magneti c field estimate s available , a n attemp t ha s bee n mad e t o refine th e period . A perio d o f 784 2 6 0 day s (21. 5 years ) turne d ou t th e mos t likely. Th e phas e magneti c curv e wit h thi s perio d i s displaye d i n Fig.2 . A s i s seen from Fig.2 , th e curv e ha s rathe r a non-unifor m filling over th e phases , an d a t phas e 0 i t ha s quit e a larg e scatte r o f points . Th e magneti c variabil it y i s mainl y o f harmoni c character , bu t apparently , ther e ar e deviation s fro m harmoni c behaviou r an d th e magneti c curv e ma y b e mor e complicated . Therefor e i t i s extremel y importan t t o continu e magneti c monitoring , whic h will mak e i t possibl e t o finally establis h th e characte r o f th e magneti c behaviour . Unde r th e assumptio n tha t th e relatio n i s sinusoida l th e parameter s ar e expresse d b y th e following formula :

204


LONG-PERIOD

MAGNETIC

VARIABILITY

OF

HD

9996


206

B Y C H K O V , G E R T H , R O L L , S H T O L '

w h e r e B 0 -- - 8 6 ± 3 6 G -- c o n s t a n t c o m p o n e n t , B 1 = 9 1 6 ± 4 5 G -- h a l f - a m p l i t u d e o f v a r i a b i l i t y , T 0 = 2 4 3 3 7 8 3 . 0 -- i n i t i a l e p o c h ,
p = 7 8 4 2 . d a y -- p e r i o d .

T h e r o o t - m e a n - s q u a r e m a g n e t i c f i e l d e s t i m a t e < B e > d e r i v e d f r o m 5 7 e s t i m a t e s b y t h e p r o c e d u r e p r o p o s e d b y B o r r a e t a l . ( 1 9 8 3 ) i s < B e > = 8 3 3 ± 2 0 4 G .

References
B a b c o c k H . W . : 1 9 4 7 , A s t r o p h y s . J . , 1 0 5 , 1 0 5 . B a b c o c k H . W . : 1 9 5 8 , A s t r o p h y s . J . S u p p l . S e r . , 3 0 , 1 4 1 . B o r r a F . E . , L a n d s t r e e t J . D . , T h o m p s o n I . : 1 9 8 3 , A s t r o p h y s . J . S u p p l . S e r . , 5 3 , 1 5 1 . P r e s t o n G . W . , W o l f f S . C . : 1 9 7 0 , A s t r o p h y s . J . , 1 6 0 , 1 0 7 1 . P y p e r D . M . , A d e l m a n S . : 1 9 8 6 , I . A . P . P . P . C o m m u n . , 2 5 , 7 6 . S c h o l z G . : 1 9 7 8 , A s t r o n . N a c h r . , 2 9 9 , 8 1 . S c h o l z G . : 1 9 8 3 , A s t r o p h y s . S p a c e S c i . , 9 4 , 1 5 9 . S h t o l ' V . G . : 1 9 9 1 , A s t r o f i z . I s s l e d . ( I z v . S A O ) , 3 3 , 1 7 6 . S h t o l ' V . G . : 1 9 9 3 , B u l l . S p e c . A s t r o p h y s . O b s . , 3 5 , 1 1 4 . W o l f f S . C . : 1 9 6 9 , A s t r o p h y s . J . , 1 5 8 , N o . 3 , P a r t 1 , 1 2 3 1 . W o l f f S . C . , B o n s a c k W . K . : 1 9 7 2 , A s t r o p h y s . J . , 1 7 6 , N o . l , P a r t 1 , 4 2 5 .