Einstein Cross

QSO 2237+0305
Observation data (Epoch J2000)
Constellation Pegasus
Right ascension 22h 40m 30.3s
Declination +3° 21′ 31″
Redshift 1.695
Distance 8,000,000,000 ly (2,500,000,000 pc)
Type LeQ
Apparent dimensions (V) less than 2"
Apparent magnitude (V) 16.78
Other designations
LEDA 69457, Z 378-15
See also: Quasar, List of quasars

The Einstein Cross (Q2237+030 or QSO 2237+0305) is a gravitational lensed quasar that sits directly behind ZW 2237+030, Huchra's Lens. Four images of the same distant quasar (plus one in the centre, too dim to see) appear around a foreground galaxy due to strong gravitational lensing.[1][2]

While gravitationally lensed light sources are often shaped into Einstein ring, due to elongated shape of lensing galaxy and quasar being off-centre, images form a peculiar cross-shape instead.[3]

The quasar's redshift indicated that it is located about 8 billion light years from Earth, while the lensing galaxy is at a distance of 400 million light years. The apparent dimensions of the entire foreground galaxy are 0.87x0.34 arcminutes, while the apparent dimension of the cross in its centre accounts for only 1.6x1.6 arcseconds.

The Einstein Cross can be found in Pegasus at 22h 40m 30.3s, +3° 21′ 31″.

Amateur astronomers are able to see some of the cross using telescopes but it requires extremely dark skies and telescope mirrors with diameters of 18 inches (46 cm) or greater.[4]

The individual images are labelled A through D (i.e. QSO 2237+0305 A), the lensing galaxy is sometimes referred to as QSO 2237+0305 G.

Hubble space telescope captures Einstein Cross.

See also

References

  1. ↑ NASA and ESA (September 13, 1990). "The Gravitational Lens G2237 + 0305". HubbleSite. Retrieved July 25, 2006.
  2. ↑ Drakeford, Jason; Corum, Jonathan; Overbye, Dennis (March 5, 2015). "Einstein's Telescope - video (02:32)". New York Times. Retrieved December 27, 2015.
  3. ↑ "How does gravitational lensing account for Einstein's Cross?". physics.stackexchange.com. Retrieved 2016-06-26.
  4. ↑ Crinklaw, Greg. "Focus on Einstein's Cross". Retrieved 2013-06-29.

External links

Coordinates: 22h 40m 31.0s, +03° 21′ 30.3″

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