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These were the most remote objects discovered at the time. The pair of galaxies were found lensed by galaxy cluster CL1358+62 (z = 0.33). This was the first time since 1964 that something other than a quasar held the record for being the most distant object in the universe. [135] [138] [139] [136] [133] [140] PC 1247–3406: Quasar 1991 − ...
The use of the parsec as a unit of distance follows naturally from Bessel's method, because the distance in parsecs can be computed simply as the reciprocal of the parallax angle in arcseconds (i.e.: if the parallax angle is 1 arcsecond, the object is 1 pc from the Sun; if the parallax angle is 0.5 arcseconds, the object is 2 pc away; etc.).
The astronomical system of units, formerly called the IAU (1976) System of Astronomical Constants, is a system of measurement developed for use in astronomy. It was adopted by the International Astronomical Union (IAU) in 1976 via Resolution No. 1, [ 1 ] and has been significantly updated in 1994 and 2009 (see Astronomical constant ).
One particularly distant body is 90377 Sedna, which was discovered in November 2003.It has an extremely eccentric orbit that takes it to an aphelion of 937 AU. [2] It takes over 10,000 years to orbit, and during the next 50 years it will slowly move closer to the Sun as it comes to perihelion at a distance of 76 AU from the Sun. [3] Sedna is the largest known sednoid, a class of objects that ...
In nearby objects (within our Milky Way galaxy) observed redshifts are almost always related to the line-of-sight velocities associated with the objects being observed. Observations of such redshifts and blueshifts have enabled astronomers to measure velocities and parametrize the masses of the orbiting stars in spectroscopic binaries , a ...
The Hubble constant is most frequently quoted in km/s/Mpc, which gives the speed of a galaxy 1 megaparsec (3.09 × 10 19 km) away as 70 km/s. Simplifying the units of the generalized form reveals that H 0 specifies a frequency (SI unit: s −1), leading the reciprocal of H 0 to be known as the Hubble time (14.4 billion years). The Hubble ...
List of NGC objects (2001–3000) List of NGC objects (3001–4000) List of NGC objects (4001–5000) List of NGC objects (5001–6000) List of NGC objects (6001–7000) List of NGC objects (7001–7840) List of IC objects; List of Messier objects; List of Caldwell objects; List of Herschel 400 objects; List of Melotte objects; List of ...
The branch of astronomy that studies objects and phenomena outside of the Milky Way galaxy, i.e. all objects not covered by galactic astronomy. extrasolar object Any astronomical object that exists outside the Solar System. The term is generally not applied to stars or any objects larger than a star or the Solar System itself, such as galaxies.