Analysis of coronal streamers photographed by white light coronagraphs flown on Aerobee 150 vehicl

Koomen, M. J.

Sandlin, G. D.

Tousey, R.

English

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*Supported by the National Aeronautics and Space 
Administration 
PHOTOGRAPHS OF CORONAL STREAMERS 
FROM A ROCKET ON 9 MAY 1967* 
R. Tousey, G. D. Sandlin, and M e  J. Koomen 
E. 0. Hulburt Center for  Space Research 
U. S.  Naval Research Laboratory 
Washington, Do C. 20390 USA 
8 0 - 0 2 . 0  - 8 4 6 
Presented at the 
International Astronomical Union Meeting 
Symposium No. 35: THE STRUCTURE AND DEVELOPMENT 
OF SOLAR ACTIVE REGIONS 
Budapest, Hungary 
https://ntrs.nasa.gov/search.jsp?R=19680023981 2020-03-12T06:31:35+00:00Z
PHOTCXX.APHS OF CORONAL STREAMERS 
FROM A ROCKET OM 9 MAP 1967* 
R. Tousey, G. D. Sandlin, and M .  J. Koomen 
E. 0. Hulburt Center for  Space Research 
U. S .  Naval Research Laboratory 
Washington, D. C. 20390 
The most recent flight of the U. S .  Naval Research Labo- 
ratory's white light coronagraphs took place on 9 May 1967. 
Two externally-occulted, small Lyot coronagraphs were built 
into the instrument compartment of the biaxial pointing- 
control section of an Aerobee-150 rocket. The instrument 
and some earlier results have been described by Tousey (1965), 
Purcell, Tousey, and Koomen (1967), and Koomen, Tousey, and 
Seal (1967). In the present noteattention is directed to the 
straight character of the streamers and to the possible 
origins of the three which appear to come from regions not 
far from the North Pole. 
Simultaneous photographs from the two instruments are 
reproduced in Figure 1, as unretouched, positive prints. The 
dark central region is the shadow cast by the external oc- 
culter; the dark sectors, in the NI of one and in the SE of 
-- 
*Supported by the National Aeronautics and Space 
Administration 
the other? are the shadows of the arms supporting each occulter. 
At the very center of one a white disc has been introduced to 
show the location and size of the sun. The other instrument 
became slightly misaligned during launch, which accounts for 
the bright crescent at the edge of the occulter's shadow. The 
decrease in brightness of the corona and streamers with 
increasing R was compensated by the vignetting action of the 
external occulter. The useful field covered the range 
3 to 9 R@ in the plane perpendicular to the line of sight. 
A few artifacts are present, caused by specks on a lens, 
and the short, bright streak in the NW of the one photograph 
is the trail of a sunlit particle just beyond the occulter. 
Mercury is seen almost out of the field in the west, and 
drawn into a short arc by the precession-caused rotation of 
the instrument around the ss-1ar vector. 
The small, black disc east of the sun is the moon. The 
rocket was launched intentionally on 9 May at 1618 UT in order 
to have the moon in the field of view. This aspect of the 
program has been described by Koomen, Tousey, and Seal (1967). 
The black character of the shadow of the occulting disk and 
of the moon shows that the instrumental stray light level 
was negligible. The mo0n9s features are clearly visible in 
earthshine on the original film. 
2 
There are many conspicuous coronal streamers, especially 
at low solar latitudes, All of the streamers are straight; 
therefore, the range beyond 3 is largely outside the 
region where the corona is controlled by complex magnetic 
fields. It will be difficult to locate the origins of the 
low-latitude streamers because of the great amount of activity 
and because of the overlapping and merging of the streamers. 
The streamers at high north latitudes can be studied in 
more detail, The NE streamer is single and appears to form 
a 21' angle with the solar axis; the NW streamer is double 
with angles of 20' and 270 to the axis, It appears unlikely 
that they really originated at high latitudes because there 
were no large prominences in suitable positions and because 
sunspots and intense active centers were not found at those 
latitudes. They could very well have come from low latitude 
centers of activity on the front or back side and thus be 
seen in projection. On the front side, however, there were 
no features from which the streamers conceivably could have 
arisen. 
An investigation was made to determine whether or not 
intense active regions on the back side might have served 
as origins for these streamers6 Examination of the Ca-K 
spectroheliograms for 25 April and 23 May, fourteen days 
3 
earlier and later t h a n  9 May, showed p l a g e s  i n  f a v o r a b l e  
l o c a t i o n s ,  a t  la t i tudes where t h e  so la r  r o t a t i o n  p e r i o d  is 
about 28 days.  These r e g i o n s  were ve ry  large and i n t e n s e ,  
c o n t a i n i n g  large s p o t s  a t  c o o r d i n a t e s  31°E, 260N under  
plage #8785, a t  19'E, 35'N under  p l a g e  #8793 which first 
appeared on 28 A p r i l ,  and a t  22'W, 23'N under  p l age  #8778. 
On 24 l a y  t h e  same r e g i o n s  persisted on t h e  s u n ,  remaining 
very  i n t e n s e  and a t  roughly t h e  same p o s i t i o n s  bu t  having  
grown markedly i n  area; the  e a s t e r n  r e g i o n ,  designated #8818 
i n  t h i s  ro t a t ion ,  covered  about 8500 m i l l i o n t h s  of the  
hemisphere,  and t h e  wes te rn  r e g i o n  covered  about  2500 
m i l l i o n t h s  of the  hemisphere.  The eastern r e g i o n  a t  2470 
l o n g i t u d e  was the  most a c t i v e  r e g i o n  on the sun  i n  May, and 
was t h e  s i t e  of t h e  pro ton  f l a r e  e v e n t s  i n  t h e  l as t  week of 
May. Average p o s i t i o n s  f o r  these r e g i o n s  were taken  and 
t r a n s f e r r e d  t o  the back of t h e  sun .  T h e i r  l o c a t i o n s  and 
approximate forms are i n d i c a t e d  011 t h e  w h i t e  disc  i n  F i g u r e  1 
as a view s e e n  through the  sun .  
A c a l c u l a t i o n  was made of t h e  a p p a r e n t  a n g l e  between 
each streamer and t h e  solar  ax is ,  u s i n g  t h e  assumed p o s i t i o n s  
of the  a c t i v e  c e n t e r s ,  making t h e  assumption t h a t  the  
streamers w e r e  r ad i a l ,  and t a k i n g  i n t o  account  t h e  t ilt  a n g l e  
4 
of t h e  s u n  and t h e  p e r s p e c t i v e .  The f o l l o w i n g  table g i v e s  
t h e  resul ts .  
TABLE I 
APPARENT ANGLE BETWEEN STREAMER AND SOLAR NORTH 
P l a g e  #/Streamer 8778 /NE 8785/NW 8793/NW 
Observed 2 1" 27g 20" 
C a l c u l a t e d  20" 2 9" 170 
These values are  i n  ve ry  good agreement ,  i n  c o n s i d e r a t i o n  of 
t h e  errors of measurement and of t h e  u n c e r t a i n t i e s  i nvo lved  
i n  e s t i m a t i n g  t h e  c e n t e r s  of t h e  p l a g e s .  
The c o n c l u s i o n  is t h a t  t h e s e  streamers came f r o m  a c t i v e  
c e n t e r s  t h a t  were 50' t o  53" h e l i o c e n t r i c  a n g l e  behind the 
l i m b ,  and t h a t  t h e y  were r a d i a l .  Because of p e r s p e c t i v e ,  
t h e y  were r e a l l y  r eco rded  t o  about 15 %. Although t h e y  
were f a v o r a b l y  l o c a t e d  t o  show any t w i s t i n g ,  t h e r e  is no 
i n d i c a t i o n  of a "garden hose" effect because t h e y  are s t r a i g h t ,  
and p r o j e c t  inward a l o n g  r a d i i  p a s s i n g  through t h e  large 
c e n t e r s  of a c t i v i t y  p r e s e n t  on t h e  rear s i d e .  
We are g r e a t l y  i n d e b t e d  t o  Dr. Helen Dodson-Prince, 
and M i s s  E. Ruth Hedeman of t h e  McMath-Hulbert Observa tory  
for making avai lable  t h e i r  solar  d a t a  and  for t h e i r  d i s c u s -  
s i o n s  of t h e  histories of t h e  active m g i o n s .  
5 
REFERENCES 
Koomen, M .  J . ,  Tousey, R . ,  and S e a l ,  R .  T.  J r . :  1967, to be 
publtshed i n  SPACE RESEARCH VIII. 
Purce l l ,  J .  D e ?  Tousey, R . ,  and Koomen, M. J . :  1967, to be 
published i n  SPACE RESEARCH VIII. 
Touseyp R e :  1965, Ann. d'Astrophys. 28, _I 600. 
6 
FIGURE CAPTION 
Simultaneous photographs of the white light corona, made 
with a pair of externally occulted Lyot coronagraphs, flown 
from the White Sands Missile Range on 9 May I967 at 1618 UT. 
Introduced into the central shadow cast by the occulter of 
one instrument is a disk showing the size and location of 
the sunp and the approximate locations and shapes of the 
plages, believed to be on the back side of the sun. 
The sharp black disc is the moon, and the bright, short arc 
at the edge of the field is Mercury. The bright arc in the 
left image is evidence of slight misalignment; the swak in 
the right image is a particle trail, out of focus because 
it was not far beyond the occulter. 
7 



Photographs of coronal streamers from a rocket on 9 May 1967

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