GLASS-z12

GLASS-z12 (formerly known as GLASS-z13) is a Lyman-break galaxy discovered by the Grism Lens-Amplified Survey from Space (GLASS) observing program using the James Webb Space Telescope's NIRCam in July 2022. Spectroscopic observations of GLASS-z12 by the Atacama Large Millimeter Array (ALMA) in August 2022 confirmed that the galaxy has a spectroscopic redshift of 12.117±0.012, making it one of the earliest and most distant galaxies ever discovered, dating back to just 350 million years after the Big Bang, 13.6 billion years ago. ALMA observations detected an emission line associated with doubly ionized oxygen (O III) at 258.7 GHz with a significance of 5σ, suggesting that there is very low dust content in GLASS-z12, if not the early universe as well. Also based on oxygen-related measurements, the age of the galaxy is confirmed.

GLASS-z12
Close-up view of GLASS-z12 from the James Webb Space Telescope
Observation data (J2000 epoch)
ConstellationSculptor
Right ascension00h 13m 59.76s
Declination−30° 19 29.1
Redshift12.117±0.012 (spectroscopic)
12.4+0.1
−0.3

12.42+0.27
−0.14

12.28+0.08
−0.07
Distance
Apparent magnitude (V)27.0 AB (F200W)
Characteristics
Mass1.0×109 M
Size~3000 ly (1 kpc)
Half-light radius (physical)500 pc
Other designations
GHZ2 · GLASS-17487
References:

GLASS-z12 derives its name from the GLASS survey that discovered it and its estimated photometric redshift of approximately z = 12.4+0.1
−0.3
. GLASS-z12 was initially announced as GLASS-z13 because it was thought to have a higher redshift of z = 13.1. This redshift value was later revised down to z = 12.4 in October 2022, resulting in the renaming of this galaxy.

GLASS-z12 has a light-travel distance (lookback time) of 13.6 billion years. However, due to the expansion of the universe, its present proper distance is 33.2 billion light-years. It was discovered alongside another galaxy, GLASS-z10, comparable to GN-z11, also one of the oldest galaxies discovered.

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