(ORDO NEWS) — An international team of astronomers announces the discovery of a new super-dim dwarf galaxy as part of the DECam Local Volume Exploration (DELVE) survey. This newly discovered galaxy, designated Pegasus IV, has an absolute magnitude of -4.25.
The so-called ultra-dim dwarf galaxies are the dimmest galaxies known to science, dominated by dark matter and chemical evolution in its infancy.
Therefore, they are considered by astronomers as the best examples of galaxies that have been preserved unchanged from the early eras of the existence of the Universe.
Now, in new work, a team of astronomers led by William Cerny of the University of Chicago in Illinois, USA, has found a new, super-dim dwarf galaxy that turns out to be a satellite of the Milky Way.
The discovery was made using data collected by the Dark Energy Camera (DECam) as part of the DELVE Sky Survey, a multi-component observing campaign that aims to provide deep, consistent observations of areas of the southern sky at high galactic latitudes.
This newly discovered ultra-dim dwarf galaxy Pegasus IV is a compact, ancient super-dim star system. Observation results show that this super-dim dwarf galaxy is at least 12.5 billion years old and has an effective radius of 133.7 light-years.
The galaxy has an absolute magnitude of -4.25, and the mass of all the stars in the system is estimated at about 4,400 solar masses.
According to the paper, the Pegasus IV dwarf galaxy has a velocity dispersion of 3.3 kilometers per second with a heliocentric velocity of -273.6 kilometers per second.
These results, together with measurements of the proper motion of stars in the Pegasus IV dwarf galaxy, show that this object is in an elliptical retrograde orbit and is currently close to the apocenter of the orbit.
In addition, the researchers were able to estimate the distance to the Pegasus IV galaxy, which was about 293,000 light-years from Earth, the paper indicates.
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