Determining Star Distance, Essay Example

In order to measure star distance, astronomers use a factor called parallax. Using this, they measure distances of nearby stars. Parallax is the visible displacement of an item because of the variation in an observer’s viewpoint. As the observer changes direction between two places, he or she observes the front object, but appears to change position against the background.

The effect can be utilized to determine the distances to closer stars. As the earth rotates the sun, a close star appears to shift against a farther located background star. Therefore, astronomers can determine the distance of a star from the earth after every six months and compare the shift in position. This apparent shift is referred to as stellar parallax (Reid et al 2009).

The formula d=1/p shows the connected between the distance of a star and the parallax angle of the star in relation to another star located on its background and far away (Reid et al 2009). The symbol d represents the distance given in parsecs while p is the angle measured in arcseconds (Reid et al 2009). Astronomers use it to calculate the star distance.

Limitating Measurement of Distance with Stellar Parallax

1. It difficult to measure the parallax angles of less than 0.01 arcsec from the earth as the earth’s atmosphere has negative effects (Reid et al 2009). Therefore, the telescopes are limited to measuring distances of stars about 1/0.1 or 100 parsecs far (Reid et al 2009). Telescopes located in space have an accuracy of 0.001. Therefore, these can be used to measure stars that are more distant.
2. Moreover, even the space-located telescopes cannot be able to measure all the stars as some are located 1,000 parsecs-30,000 parsec (Reid et al 2009). For example, these stars are out of our galaxy and belong to Milky Way (Henry et al 2009).

References

Reid, M. J., Menten, K. M., Zheng, X. W., Brunthaler, A., Moscadelli, L., Xu, Y., … & Bartkiewicz, A. (2009). Trigonometric parallaxes of massive star-forming regions. VI. Galactic structure, fundamental parameters, and noncircular motions. The Astrophysical Journal, 700(1), 137.

Henry, T. J., Jao, W. C., Subasavage, J. P., Beaulieu, T. D., Ianna, P. A., Costa, E., & Méndez, R. A. (2006). The solar neighborhood. XVII. Parallax results from the CTIOPI 0.9 m program: 20 new members of the recons 10 PARSEC sample. The Astronomical Journal, 132(6), 2360.