The nucleus of the Seyfert galaxy NGC 1275 was observed in the B system on 1 December 1989 with seeing 0, 7 seconds using the Zeiss-1000 telescope on Mount Majdanak in Central Asia. Special methods of processing reveal low-contrast details. The nucleus and circumnucleus are stretched in NW-SE direction. There are two narrow filaments near the nucleus in position angles roughly 340 degrees and 320 degrees. The first is directed near the radio jet of the nucleus, the second has broken details curved to the NW or toward the high-velocity system of NGC 1275

Dudinov, V. N.

Novikov, S. B.

Pronik, I. I.

Tsvetkova, V. S.

English

NASA Technical Reports Server

N - 1  1 
SIGNS OF INTERACTION OF THE NGC 1275 NUCLEUS WITH THE 
HIGH-VELOCITY SYSTEM ACCORDING TO OY7 SEEING OBSERVATIONS 
V. N. Dudinov and V. S .  Tsve tkova  
As t ronomica l  O b s e r v a t o r y  of Kharkov U n i v e r s i t y ,  USSR 
S. B. Novikov 
S t e r n b e r g  S t a t e  As t ronomica l  I n s t i t u t e ,  USSR 
I. I. P r o n i k  
Crimean A s t r o p h y s i c a l  O b s e r v a t o r y ,  USSR 
”- 
ABSTRACT. The n u c l e u s  of the S e y f e r t  g a l a x y  NGC 1275 w a s  
obse rved  i n  t h e  B sys t em on 12-1-1989 w i t h  s e e i n g  0 , 7  u s i n g  t h e  
II 
Zeiss-1000 t e l e s c o p e  on Mount Majdanak i n  C e n t r a l  A s i a .  S p e c i a l  
methods of p r o c e s s i n g  r e v e a l  l o w - c o n t r a s t  d e t a i l s .  The n u c l e u s  
and c i r c u m n u c l e u s  are s t r e t c h e d  i n  NW-SE d i r e c t i o n .  The re  are 
two nar row f i l a m e n t s  n e a r  t h e  n u c l e u s  i n  p o s i t i o n  a n g l e s  r o u g h l y  
340’ and 320O. The f i r s t  is d i r e c t e d  n e a r  t h e  r a d i o  je t  of t h e  
n u c l e u s ,  t h e  second h a s  broken  d e t a i l s  cu rved  t o  t h e  NW or toward 
t h e  h i g h - v e l o c i t y  sys t em of NGC 1275. 
The NGC 1275 system c o n s i s t s  of a main g E  g a l a x y ,  hav ing  a 
r a d i a l  v e l o c i t y  5200 km/s (Burb idge ,  Burbidge  1965)  and of an  
i r r e g u l a r  g a l a x y  (L-galaxy - l a t e  t y p e  sp i r a l )  w i t h  r a d i a l  
v e l o c i t y  8200 km/s,  l o c a t e d  t o  t h e  NW of t h e  main one  (Minkowski,  
1 9 5 7 ) .  Both g a l a x i e s  are r i c h  i n  gas. The gas of t h e  main 
42 I 
https://ntrs.nasa.gov/search.jsp?R=19910007605 2020-03-19T19:50:06+00:00Z
g a l a x y  looks l i k e  a g i a n t  Crab ,  or b u r s t ,  of d imens ions  e q u a l  t o  
t h o s e  of t h e  gE g a l a x y  (Burb idge ,  Burbidge  1965; Lynds 1970) .  
The n a t u r e  of  t h e  L-galaxy is w i d e l y  d i s c u s s e d .  The f irst  
d i s c o v e r e r  of t h i s  g a l a x y ,  Minkowski, supposed  t h a t  it is 
c o l l i d i n g  w i t h  t h e  g E  one. The Burb idges  (1965)  d i s c u s s e d  t h e  
e j e c t i o n  of L from gE g a l a x y ,  S h i e l d s  and Oke (1975)  and van den  
Bergh (1977)  supposed  t h a t  L-galaxy is p r o j e c t e d  to  t h e  gE 
g a l a x y .  The c o l l i d i n g  h y p o t h e s i s  is f a v o r e d  from H I  o b s e r v a t i o n s  
of L-galaxy i n  t h e  2 1  c m  H 1  l i n e  found i n  a b s o r p t i o n  a g a i n s t  t h e  
radio cont inuum e m i s s i o n  of t h e  NGC 1275 b r i g h t  n u c l e u s  (de Young 
e t  a l . ,  1 9 7 3 ) .  I n  a l l  h y p o t h e s e s  t h e r e  are i n t r i n s i c  
d i f f i c u l t i e s .  The i m p o r t a n t  problem up t o  now is how t h e  t w o  
g a l a x i e s  i n t e r a c t  and whether  t h e  i n t e r a c t i o n  e x i s t s  or no t .  One 
s u p p o s i t i o n  a b o u t  t h e  s i te  of i n t e r a c t i o n  w a s  made by M e t i k  and 
P r o n i k  (1979)  : n e a r  t h e  s t a r l i k e  o b j e c t  l o c a t e d  7" NE from t h e  
NGC 1275 n u c l e u s  ( l a t e r  o b j e c t  " b " ) .  Meaburn e t  a l .  (1989)  
supposed  t h a t  i n t e r a c t i o n  p roduces  a f i n e  f i l a m e n t  of o p t i c a l  
cont inuum e m i s s i o n  w i t h  i o n i z e d  k n o t s  a l o n g  its l e n g t h  p r e s e n t e d  
i n  PA = 295'. For f u r t h e r  d i s c u s s i o n  of t h i s  problem it is 
i m p o r t a n t  to  r e v e a l  the  d e t a i l s  of t h e  n u c l e u s  and c i r c u m n u c l e u s  
of NGC 1275. 
The Burb idges  were t h e  f i r s t  t o  d i s c o v e r  i r r e g u l a r i t y  i n  t h e  
s t r u c t u r e  of t h e  NGC 1275 n u c l e u s  ( 1 9 6 5 ) :  t h e y  p o i n t e d  o u t  a k n o t  
3'' t o  t h e  NW of it ( l a t e r  d e t a i l  "c") .  M e t i k  and P ron ik  (1979,  
1984,  1987,  1988, a b , b )  showed t h a t  t h e  c i r c u m n u c l u e s  is 
s t r e t c h e d  i n  t h e  d i r e c t i o n  of t h i s  arched d e t a i l  "c" i n  W 
cont inuum and i n  1 4  e m i s s i o n  l i n e s .  T h i s  s t r e t c h e d  s t r u c t u r e  
422 
c o n s i s t s  of  b l u e  stars and gas .  Its d i r e c t i o n  is v e r y  n e a r  to  
t h e  r a d i o  je t  one ( P e d l a r  e t  a l . ,  19831, I t  was supposed  t h a t  
active n u c l e u s  o f  NGC 1275 i n t e r a c t s  w i t h  t h e  c i r c u m n u c l e u s  
t h r o u g h  t h i s  s t r e t c h e d  s t r u c t u r e .  N o w  new d e t a i l s  of 
c i r c u m n u c l e a r  r e g i o n  of  NGC 1275 are o b t a i n e d  u s i n g  
p h o t o n e g a t i v e s  w i t h  r e s o l u t i o n  0,7.  
I1 
O b s e r v a t i o n s  
C e n t r a l  A s i a  w i t h  
n e g a t i v e s  w i t h  15 
system. F i g u r e  1 
were made 12-1-89 on mounta in  Majdanak i n  
0 ,7  s e e i n g  u s i n g  the Zeiss-1000 t e l e s c o p e .  S i x  
min e x p o s u r e  were o b t a i n e d  i n  t h e  B p h o t o m e t r i c  
shows a p r i n t  of one of t h e  n e g a t i v e s .  One c a n  
I1 
see t h e  n u c l e u s  "a", s t a r l i k e  o b j e c t  "b" and stars - p h o t o m e t r i c  
s t a n d a r d s :  C ,  C 1 ,  C2, C3, 1, 2 - from L y u t y i ' s  l ist (19721,  D ,  
D 1 ,  D 2 ,  D3, D4 - s e c o n d a r y  s t a n d a r d s ,  o b t a i n e d  by e x t r a p o l a t i o n .  
A l l  measurements  were made w i t h  an iris pho tomete r .  The r e s u l t s  
are  shown i n  T a b l e  1. 
T a b l e  1. B magn i tudes  of  n u c l e u s  "a" and o b j e c t  "b" and 
s e c o n d a r y  s t a n d a r d s  near t h e  n u c l e u s  of NGC 1275 
d e t a i l ,  
s t a r  B s t a r  B 
a 1 5 , 7 5 t 0 , 0 8  
b 16,33*0,01 
D 14,05*0,05 
D I  15,83*0,08 
D2 15,56&0,05 
D3 16,16&0,10 
D4 16,41&0,10 
The magni tude  of o b j e c t  "b" is i n  a c c o r d a n c e  w i t h  S e l o v e ' s  
estimate €3 = 16y3 (1969) .  
f rom its p h o t o m e t r i c  prof i le  i n  a circle of 2" d i a m e t e r  is 
15y63 v e r y  n e a r  to  T a b l e  l ' s  v a l u e .  
The magni tude  of n u c l e u s  "a" o b t a i n e d  
Accord ing  to  L y u t y i  (1991)  
42 3 
. . 
0 .  * c  .( . j  
0 
0 
0 . 
' E .  
. 
. 
i .  
. 
a 
0 
4 
b . .  l-loo" I . 
F i g u r e  1. P h o t o  of t h e  NGC 1275 r e g i o n  i n  t h e  B p h o t o m e t r i c  
sys t em,  o b t a i n e d  w i t h  t h e  Zeiss-1000 telescope on Mount Majdanak 
12-1-89. The p h o t o m e t r i c  s t a n d a r d s  are p o i n t e d .  a - 
c i r c u m n u c l e u s ,  b - s t a r l i k e  object (see t e x t ) .  
the  a c t i v e  n u c l e u s  of NGC 1275 g a l a x y  h a s  been i n  a deep minimum 
f r o m  1980 up t o  now. O b s e r v a t i o n s  made by Zasov and L y u t y i  
(1973) i n  1967-1970 g i v e  B(5") = 14:61. Now on Februa ry  1988 and 
October 1989 L y u t y i ' s  data g i v e  B(5") = 15y74: - ly13 w e a k e r  t h a n  
i n  y e a r s  of t h e  n u c l e u s '  high a c t i v i t y .  The d imens ion  of t h e  
n u c l e u s  also decreases. Ob ta ined  i n  1977 it was -1,s ( M e t i k ,  
I( 
P r o n i k ,  1984). Nowadays t h e  d imens ion  of t h e  n u c l e u s  w a s  
424 
II 
c a l c u l a t e d  u s i n g  0 , 7  r e s o l u t i o n  o b s e r v a t i o n  on 12-1-89. Taking  
i n t o  a c c o u n t  t h a t  t h e  b r i g h t n e s s  d i s t r i b u t i o n s  i n  t h e  images of 
o b j e c t s  "a" and "b" are n e a r  t o  G a u s s i a n  t h e  d imens ions  of t h e  
o b j e c t s  can  be c a l c u l a t e d  u s i n g  t h e  r e l a t i o n :  
here "0, a t 8  u2 are d i s p e r s i o n s  of o b s e r v e d ,  t r u e  and s t e l l a r  
p h o t o m e t r i c  p r o f i l e s  r e s p e c t i v e l y .  O b j e c t  "b",  to  t h e  l i m i t s  of 
t h e  errors, is n o t  d i s t i n c t  from t h e  s t a r .  The t r u e  FWHM of t h e  
II 
n u c l e u s  is 0,s. Thus w i t h  t h e  d e c r e a s e d  l e v e l  of n u c l e a r  
a c t i v i t y  i ts dimens ion  d e c r e a s e d  too. 
11 
The b e s t  n e g a t i v e s  a v a i l a b l e  ( f o r  s t e l l a r  FWHM = 0 ,7 )  were 
t a k e n  for special  p r o c e s s i n g .  A l l  n e g a t i v e s  s e l e c t e d  were added 
c w i t h  t h e  h e l p  of o p t i c a l  combining equipment .  The combined 
p o s i t i v e  w a s  p u t  f o r  l i n e a r  f i l t r a t i o n  u s i n g  t h e  o p t i c a l  
c o h e r e n c e  a r r angemen t  of Kharkov U n i v e r s i t y  (Dudinov e t  a l . ,  
1979,  1989; Tsve tkova  e t  a l . ,  1984) .  
F i g u r e  2 shows t h e  p h o t o  of t h e  c i r c u m n u c l e u s  of NGC 1275 
o b t a i n e d  a f t e r  summed image f i l t r a t i o n .  Weakening of t h e  
n u c l e u s ,  h i g h  s p a t i a l  r e s o l u t i o n  and s p e c i a l  p r o c e s s i n g  methods 
permit u s  t o  r e v e a l  new d e t a i l s  i n  t h e  c i r cumnuc leus  of NGC 
1275.  I n  a d d i t i o n  t o  a r c h  "c" t h e r e  are s t r u c t u r e s  c o n n e c t i n g  it 
w i t h  t h e  n u c l e u s  and s t r u c t u r e s  i n  o p p o s i t e  SE s i d e .  F i g u r e  3 
0 
shows i s o p h o t e s  of t h i s  r e g i o n  o b t a i n e d  w i t h  s c a n n i n g  s t e p  0,25.  
F i g u r e s  2 and 3 show t h a t  n u c l e u s  of NGC 1275 is s t r e t c h e d  
i n  t h e  NW-SW d i r e c t i o n  a t  a l l  i n t e n s i t y  l e v e l s  from 0.9 t o  0.2. 
42 5 
F i g u r e  2, Photo of t h e  c i r c u m n u c l e u s  of NGC 1275 and object "b" 
a f te r  s p a t i a l  p r o c e s s i n g .  I ,  I1 - f i l a m e n t s  of l o w  i n t e n s i t y  
e m i s s i o n .  
and t h i s  s t r e t c h i n g  is obse rved  t o  t h e  d i s t a n c e s  f 5 "  or Imax 
k1800 pc from t h e  n u c l e u s .  The s t r e t c h e d  c i r c u m n u c l e u s  
measu r ing  3.5 or 1200 pc is d i v i d e d  i n t o  t w o  streams i n  its NW 
I t  
p a r t :  I - i n  PA -3400; I1 - i n  PA -3200. The f i r s t  h a s  an  
e x t e n s i o n  t o  t h e  SE s i d e  of t h e  n u c l e u s ,  Its PA is v e r y  n e a r  t h e  
PA of t h e  n u c l e a r  radio je t  o b s e r v e d  a t  73 c m  (Ped la r  e t  ala 
19831, The second f i l a m e n t  (11) has  no c o n t i n u a t i o n  on t h e  SE 
s ide  of  t h e  n u c l e u s ,  I t  e n v e l o p s  t h e  n u c l e u s  from t h e  W side by 
many l i t t l e  cu rved  streams, t h e  l o n g e s t  of them n e a r  t h e  PA 300 
o f  g a s  k n o t s  obse rved  by Meaburn e t  a l .  (1989) and t h e  d i r e c t i o n  
of t h e  L-galaxy. Arch "c" c o n n e c t s  f i l a m e n t s  I and I1 i n  t h e  NW 
p a r t .  Its b r i g h t n e s s  is no t  homogeneous. The ex tended  w e a k e s t  
\ 
42 6 
Figure 3 .  IsQphotes of circumnucleus of NGC 1275. Step of 
scanning is 0.25. Intensities are in units of I,, of the 
nucleus. 
emission of the level < 0.2 I,, (of the nucleus) on SE side has 
a curved jut directed to object "b" which, at low intensity 
levels, has emission directed to this feature. 
What may be the nature of filaments I and I1 of Figure 2 and 
3 1  In the B photometric system the lines E0111 and [OIIII of the 
low and high velocity gas are passed. So it is not necessary to 
suppose, that filaments I and I1 consist but of stars, but they 
may contain gas of low and high velocity. Spectral investigation 
(Metik, Pronik, 1979) shows that arch "c" is a superassociation 
of early-type stars of dimension -1000 pc. It is rich in gas and 
42 7 
belongs to the low-velocity system. The spectra of the SE 
stretched part of the NGC 1275 circumnucleus also show gas of low 
and partly high velocity. For the interpretation of filaments I 
and I1 it is important to observe their spectra with high 
. 
spectral and position resolutions. 
In conclusion one can say that photo of NGC 1275 
*I 
circumnucleus obtained with spatial resolution 0.7 in B shows 
signs of interaction with: I - the radio jet, 2 - knots of gas 
observed by Meaburn et al. (1989) on the NW side of the nucleus 
and 3 - object "b". The most prominent interaction is with the 
radio jet. Interactions 2 and 3 are at lower levels. 
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Signs of interaction of the NGC 1275 nucleus with the high-velocity system according to 0.7 sec seeing observations

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