The farther an object is from the observer,
the smaller its parallax is.
Vega would have a greater parallax due to its closer distance to Earth compared to Arcturus. Parallax is the apparent shift in position of an object when viewed from different perspectives, and the nearer an object is to the observer, the larger its parallax.
Parallax is the apparent change in postion of an object when looked at from two different places. Astronomers use parallax to find how far away nearby stars are.
At larger distance, the parallax becomes smaller, and therefore harder to measure. Even the closest star (Toliman) has a parallax of less than one arc-second (1/3600 of a degree), which is difficult to measure. Stars that are farther away have a much smaller parallax.
smaller
The reciprocal of the parallax is taken. For example, if the stellar parallax is 1 second, the distance is 1/1 = 1 parsec; if the parallax is 0.1 second, the distance is 1/0.1 = 10 parsecs, etc.
The parallax angle of such distant objects is way too small to be measured. In general, the farther away an object, the smaller is its parallax angle.
The farther the object, the smaller its parallax. In this case, the parallax is about 1/300,000 of an arc-second (and an arc-second is 1/3600 of a degree) - way too small to measure. Perhaps you will eventually find a way to measure smaller parallax angles.
Vega would have a greater parallax due to its closer distance to Earth compared to Arcturus. Parallax is the apparent shift in position of an object when viewed from different perspectives, and the nearer an object is to the observer, the larger its parallax.
farther away
Parallax is the apparent change in postion of an object when looked at from two different places. Astronomers use parallax to find how far away nearby stars are.
At larger distance, the parallax becomes smaller, and therefore harder to measure. Even the closest star (Toliman) has a parallax of less than one arc-second (1/3600 of a degree), which is difficult to measure. Stars that are farther away have a much smaller parallax.
Yes, the size of an object can appear to change as the observer moves closer to or farther away from the object due to perspective. When an observer moves closer to an object, it may appear larger, and when moving farther away, it may appear smaller.
A parallax is hard to measure if it is very small - and this happens when the corresponding object is very far away.
This can't be measured directly (as in, applying a measuring stick), so the distances are calculated in other ways. Several methods are used; for a start, for nearby stars, the star's parallax is measured. The smaller the parallax, the farther away the star is. Parallax is the apparent change in position, of a star, compared to the far-away background, as Earth moves from one side of its orbit, to the other.This can't be measured directly (as in, applying a measuring stick), so the distances are calculated in other ways. Several methods are used; for a start, for nearby stars, the star's parallax is measured. The smaller the parallax, the farther away the star is. Parallax is the apparent change in position, of a star, compared to the far-away background, as Earth moves from one side of its orbit, to the other.This can't be measured directly (as in, applying a measuring stick), so the distances are calculated in other ways. Several methods are used; for a start, for nearby stars, the star's parallax is measured. The smaller the parallax, the farther away the star is. Parallax is the apparent change in position, of a star, compared to the far-away background, as Earth moves from one side of its orbit, to the other.This can't be measured directly (as in, applying a measuring stick), so the distances are calculated in other ways. Several methods are used; for a start, for nearby stars, the star's parallax is measured. The smaller the parallax, the farther away the star is. Parallax is the apparent change in position, of a star, compared to the far-away background, as Earth moves from one side of its orbit, to the other.
If a star's parallax is too small to measure, it means that the star is far from Earth. Parallax measurements are used to determine the distance of nearby stars by observing their apparent shift in position as Earth orbits the Sun. Stars with large parallaxes are closer to Earth, while stars with small or undetectable parallaxes are further away.
smaller
I'm not sure what a "parsac" is, but "parsec" is the shortcut name for "PARallax SECond of arc", the distance away from the Sun where another object would appear to have an angular parallax shift of one arc-second as compared to the distant background stars. It is approximately equal to 3.26 light-years.