(ORDO NEWS) — Scientists from Argentina, Brazil and Venezuela have revealed the nature of a giant extragalactic structure, which is located in the zone of avoidance – a region of the sky in the southern hemisphere of the Earth, obscured by dust and stars of the Milky Way disk and inaccessible to optical observations. It turned out that it is a previously unknown galactic cluster.
Previous observations from the Milky Way Central Infrared Survey (VVV) have shown that there is a 1.636 square degree region in the zone of avoidance with an unusually high concentration of potential galaxies.
In this region, labeled b204, a 15-arc-minute radius area with an unusually high density of extended infrared sources stands out. It contains 118 visually confirmed galaxies, which is three times the density in the rest of the region.
Astronomers have made new observations to better characterize the nature of this superdense region by determining the redshift of several sources.
Redshift is the shift of spectral lines to the long wavelength (red) region of the spectrum due to the Doppler effect, when the source moves away from the observer and the wavelength of its radiation increases.
The spectra of five candidate galaxies were obtained using the Flamingos 2 spectrograph on the Gemini South telescope of the Gemini Observatory.
Scientists have found that all spectra contain absorption lines that correspond to the expected characteristics of galaxies, given their morphology and stellar composition.
The spectroscopic redshift was calculated for each individual galaxy, taking into account all the lines identified in each spectrum, and the resulting average redshift was found to be 0.225 ± 0.014, which corresponds to a light travel time of 2.5 billion years.
The size of the superdense region reaches about two million light years, which is typical for a typical galactic cluster. According to researchers, it can include up to 58 galaxies.
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