GLASS-z12 | |
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![]() Close-up view of GLASS-z12 from the James Webb Space Telescope | |
Observation data (J2000 epoch) | |
Constellation | Sculptor |
Right ascension | 00h 13m 59.76s [1] |
Declination | −30° 19′ 29.1″ [1] |
Redshift | 12.117±0.012 (spectroscopic) [2] 12.4+0.1 −0.3 [1] 12.42+0.27 −0.14 [3] 12.28+0.08 −0.07 [4] |
Distance |
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Apparent magnitude (V) | 27.0 AB (F200W) [1] |
Characteristics | |
Mass | ≈1.0×109 M☉ |
Size | ~3000 ly (1 kpc) |
Half-light radius (physical) | 500 pc |
Other designations | |
GHZ2 [6] [7] ·GLASS-17487 [3] | |
References: [1] |
GLASS-z12, also named GHZ2 (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. [8] [9]
It has a spectroscopic redshift of 12.34, making it one of the most distant galaxies and astronomical objects ever discovered. According to current theory, this redshift corresponds to a time about 13.44 billion years ago, approximately 355 million years after the Big Bang, or about 2,57% of its current age. [10]
GLASS-z12/GHZ2, was initially discovered as a robust z ≈ 12.0–12.5 candidate by Castellano et al. and Naidu et al. in the GLASS-JWST Early Release Science NIRCam field. The two discovery papers appeared on arXiv the same day. Hence these two names for this galaxy of GLASS-z12 (Naidu et al. 2022) and GHZ2 (Castellano et al. 2022a) [11] .
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. [1] GLASS-z12 was initially announced as GLASS-z13 because it was thought to have a higher redshift of z = 13.1. [7] [2] This redshift value was later revised down to z = 12.4 in October 2022, resulting in the renaming of this galaxy. [1]
It was discovered alongside another galaxy, GLASS-z10, comparable to GN-z11, also one of the oldest galaxies discovered. [12]
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 360 million years after the Big Bang, 13.44 billion years ago. [12] [5] 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. [2] Also based on oxygen-related measurements, the age of the galaxy is confirmed. [13] [14]
GLASS-z12 has a light-travel distance (lookback time) of 13.4 billion years. [5] However, due to the expansion of the universe, its present proper distance is 32.718 billion light-years. [5]
This galaxy was observed again in October 2023 by the James Webb Space Telescope with the NIRSpec and MIRI spectrographs, making it the most distant redshift galaxy of z = 12.34 with full spectroscopic coverage from ultraviolet (UV) to optical [11] [15] .
According to current ΛCDM parameters (H0 = 67.4, Ωm = 0.315, ΩΛ = 0.685), this redshift of 12.34 corresponds to a light-travel distance (lookback time) of 13.44 billion years. However, due to the expansion of the universe, its comoving distance is 32.837 Gly [16] .