![]() ![]() Einstein’s theory of general relativity predicts that the wavelength of electromagnetic radiation will lengthen as it climbs out of a gravitational well. Spectral lines can also be redshifted due to the influence of strong gravitational fields – this is not surprisingly known as gravitational redshift. The cosmological redshift of an object provides an estimate of its distance, through Hubble’s law. Where λ obs is the observed wavelength of the spectral line, and λ rest is the rest wavelength of the spectral line. For nearby objects, the cosmological redshift, Z is given by: The most common reason for this redshift effect is denoted cosmological redshift, and is caused by the expansion of the Universe. There are several explanations for this redshift phenomenon. In most cases the wavelength of the spectral lines are longer and thus are shifted towards the red end of the spectrum – they are redshifted. However, when astronomers observe spectral lines in extragalactic objects (such as galaxies and quasars), they find that the wavelength of the observed spectral lines differs from the laboratory experiments. These photons are manifest as either emission or absorption lines in the spectrum of an astronomical object, and by measuring the position of these spectral lines, we can determine which elements are present in the object itself or along the line of sight. ![]() Laboratory experiments here on Earth have determined that each element in the periodic table emits photons only at certain wavelengths (determined by the excitation state of the atoms). ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |