A1689-zD1 is a

galaxy A galaxy is a Physical system, system of stars, stellar remnants, interstellar medium, interstellar gas, cosmic dust, dust, and dark matter bound together by gravity. The word is derived from the Ancient Greek, Greek ' (), literally 'milky', ...

in the Virgo constellation. It was a candidate for the most distant and therefore earliest-observed galaxy discovered , based on a

photometric redshift A photometric redshift is an estimate for the recession velocity of an astronomical object such as a galaxy or quasar, made without measuring its spectrum. The technique uses photometry (that is, the brightness of the object viewed through various ...

. If the

redshift In physics, a redshift is an increase in the wavelength, and corresponding decrease in the frequency and photon energy, of electromagnetic radiation (such as light). The opposite change, a decrease in wavelength and increase in frequency and e ...

, z~7.6, is correct, it would explain why the galaxy's faint

light Light, visible light, or visible radiation is electromagnetic radiation that can be visual perception, perceived by the human eye. Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400– ...

reaches us at

infrared Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...

wavelengths. It could only be observed with

Hubble Space Telescope The Hubble Space Telescope (HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the Orbiting Solar Observatory, first space telescope, but it is one of the largest and most ...

Near Infrared Camera and Multi-Object Spectrometer The Near Infrared Camera and Multi-Object Spectrometer (NICMOS) is a Measuring instrument, scientific instrument for infrared astronomy, installed on the Hubble Space Telescope (HST), operating from 1997 to 1999, and from 2002 to 2008. Images produ ...

(NICMOS) and the

Spitzer Space Telescope The Spitzer Space Telescope, formerly the Space Infrared Telescope Facility (SIRTF), was an infrared space telescope launched in 2003, that was deactivated when operations ended on 30 January 2020. Spitzer was the third space telescope dedicate ...

's Infrared Array Camera exploiting the natural phenomenon of

gravitational lens A gravitational lens is matter, such as a galaxy cluster, cluster of galaxies or a point particle, that bends light from a distant source as it travels toward an observer. The amount of gravitational lensing is described by Albert Einstein's Ge ...

ing: the

galaxy cluster A galaxy cluster, or a cluster of galaxies, is a structure that consists of anywhere from hundreds to thousands of galaxies that are bound together by gravity, with typical masses ranging from 1014 to 1015 solar masses. Clusters consist of galax ...

Abell 1689 Abell 1689 is a galaxy cluster in the constellation Virgo (constellation), Virgo over 2.3 billion light-years away. Details Abell 1689 is one of the biggest and most massive galaxy clusters known and acts as a gravitational lens, distorting the i ...

, which lies between

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

and A1689-zD1, at a distance of 2.2 billion

light-year A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astr ...

s from us, functions as a natural "magnifying glass" for the light from the far more distant galaxy which lies directly behind it, at 700 million years after the

Big Bang The Big Bang is a physical theory that describes how the universe expanded from an initial state of high density and temperature. Various cosmological models based on the Big Bang concept explain a broad range of phenomena, including th ...

, as seen from Earth.

References

{{DEFAULTSORT:A1689-zD1 Virgo (constellation) Dwarf galaxies Gravitational lensing Astronomical objects discovered in 2008

See also

References