Unveil the secrets of NGC 4921, an enigmatic spiral-barred galaxy situated 320 million light-years away in the Coma Berenices constellation. This celestial body, also known as UGC 08134 and PGC 044899, was first spotted by William Herschel on April 11, 1785.
A Closer Look at NGC 4921's Structure
Upon closer inspection, NGC 4921 reveals a robust bar structure at its core, encircled by a dusty ring brimming with hot blue stars. Faint yet majestic, the spiral structure of NGC 4921 unveils itself in the galaxy's outer periphery.
NGC 4921: An Anaemic Galaxy
This galaxy is known for its low star formation rate which earns it the label of an 'anaemic galaxy'. This results in a remarkably low surface brightness, setting NGC 4921 apart from its cosmic counterparts.
Velocity and Location within the Cluster
Positioned near its cluster's centre, NGC 4921 moves at a high relative speed of 7,560 km/s. Radio observation data indicates a small amount of neutral hydrogen, which appears to be disturbed towards the southeast spiral arm. This disturbance may be due to interaction with the intergalactic medium, possibly leading to gas removal.
The Novel Boomerang Effect
Recently, NGC 4921 has piqued the interest of the scientific community with the discovery of a new phenomenon called the boomerang effect. This involves streams of molecular gas being stripped from the galaxy, only to circle back and return later.
The Image: A Sight to Behold
The composite optical image of NGC 4921, captured by the Hubble Space Telescope, is a sight to behold. It was developed using broadband filters centred at 450 nm (B-band, blue) and 850 nm (I-band, red), with the green channel created by merging data from both filters.
Image Credit: NASA, ESA and K. Cook (Lawrence Livermore National Laboratory, USA)
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