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Q0957 plus 561)
The Twin Quasar or Old Faithful is also known as Q0957+561, or QSO 0957+561. It was the first identified gravitationally lensed object.
Q0957+561 A (QSO 0957+561 A) and Q-057+561 B (QSO 0957+561 B) is a double-imaged quasar, meaning than an intervening mass concentration between Earth and the quasar bends light so that two images of the quasar appears in the sky. This is known as gravitational lensing, and is a consequence of Einsteinian warped space-time. The quasar lies at redshift z=1.41, while the lensing galaxy lies at redshift z=0.355 (7.8 billin ly). The lensing galaxy lines almost in line with the B image, lying 1" off. The quasar lies 10" north of NGC3079, in the constellation Ursa Major.
The Twin Quasar's two images are separated by 6". Both images have an apparent magnitude of 17, with the A component having 16.7 and the B component having 16.5 . There is a 1.4 year time lag between the two images.
The lensing galaxy, G1, is a giant elliptical, of type cD, lies within a cluster of galaxies, that also contribute to the lensing.
- A microlensing event in 1996 observed by R. E. Schild in the A lobe has led to a controversial, and unconfirmable speculation that a 3 Earth mass planet is possibly in the lensing galaxy. This would be the most distant planet, if it could be confirmed, where the lensing galaxy is.
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