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Questions about annual aberration and annual parallax of stars



 
 
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  #1  
Old August 6th 06, 06:06 PM posted to sci.astro
subhash
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Posts: 9
Default Questions about annual aberration and annual parallax of stars

Dear members,
Please help me to answer the following querries about the above
subject.
1. It is known that the major axis of parallatic ellipse and of
aberrational ellipse are parallel to the ecliptic and their minor
axis of both the ellipse are perpendicular to the ecliptic. I want
to know that do the both axis of the both ellipses are coincide in
such a way that the centre of the both ellipses is same i.e. do the
both ellipses are concentric if not then what are their relative
posistions?
2. Do the ratio of major axis and minor axis of both the individual
ellipses are same or differ?
3. In nautical astronomy bu B.Krasavtsev, B.Khlyustin published by
Mir publisher 1970 edition, on page no. 102-
"Due to aberration the image of a star will describe on the
celestial sphere an ellipse with dimensions tens of times greater
than the ellipse due to parallax and the directions of its axis will
be different."
How it is possible when the parallax varies for star to star and the
major axis of the parallatic ellipse also changes and the major axis
of the aberrational ellipse being 20.47 having a constant value then
how is it possible that the ratio of the both of the major axis will
be always of value 10.
I will be oblidged for the answers.

Yours'
Subhash chand Jain


  #2  
Old August 7th 06, 01:30 PM posted to sci.astro
[email protected]
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Posts: 118
Default Questions about annual aberration and annual parallax of stars


subhash wrote:
Dear members,
Please help me to answer the following querries about the above
subject.
1. It is known that the major axis of parallatic ellipse and of
aberrational ellipse are parallel to the ecliptic and their minor
axis of both the ellipse are perpendicular to the ecliptic. I want
to know that do the both axis of the both ellipses are coincide in
such a way that the centre of the both ellipses is same i.e. do the
both ellipses are concentric if not then what are their relative
posistions?
2. Do the ratio of major axis and minor axis of both the individual
ellipses are same or differ?
3. In nautical astronomy bu B.Krasavtsev, B.Khlyustin published by
Mir publisher 1970 edition, on page no. 102-
"Due to aberration the image of a star will describe on the
celestial sphere an ellipse with dimensions tens of times greater
than the ellipse due to parallax and the directions of its axis will
be different."
How it is possible when the parallax varies for star to star and the
major axis of the parallatic ellipse also changes and the major axis
of the aberrational ellipse being 20.47 having a constant value then
how is it possible that the ratio of the both of the major axis will
be always of value 10.
I will be oblidged for the answers.

For a start the Earth's orbit is nearly circular, only very recently
has it been possible to observe non circularity directly on stars.

Basically aberration is at right angles to parallax. Parallax is the
distance the Earth has moved, aberration is the speed of the Earth.
With a more or less circular orbit this is at right angle. Check it out
by drawing it.

*^ Parallax
* *
* *
* 0 *^ Aberration


In the case of an ellipse there is no absolutely straightforward exact
answer. The algebra is a little messy although these broad principles
apply.

  #3  
Old August 8th 06, 06:06 AM posted to sci.astro
subhash
external usenet poster
 
Posts: 9
Default Questions about annual aberration and annual parallax of stars

Dear Sir,
Received your valuable explaination of my querries but still I want the
further clearification of the following -
The measurement of the major axis of the ellipses formed by stellar
aberration and parallax by taking the positional photographs in the
observatories of the star under consideration time to time in the
duration one year then the major axis are majored of both the ellipses
given the value of stellar aberration and parallax respectively. The
value of the major axis of aberrational ellipse is 20.47 as a constant
for all the stars while the value of the parallax ellipse changes star
to star. The maximum value being .772 arc-second for the nearest star
Proxima Cen while this value is different for other distant stars. The
distances of the stars is calculated as 1/parallax arc-second.
Now my problem is the value of major axis for the aberrational ellipse
is perfectly constant 20.47 for each star or it varies by slight values
if it varies then what is the lower and upper limit of variation.
I will be much oblidged for the reply or the suggestion that where can
I get the proper detailed answer.
With deep regards,

S.C. Jain
e-mail

 




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