The NASA/ESA Hubble Space Telescope has produced this beautiful image of the cometary dwarf galaxy NGC 4861.
This Hubble image shows the cometary dwarf galaxy NGC 4861, which lies in the constellation of Canes Venatici, about 22.8 million light-years away. Image credit: NASA / ESA / Hubble.
NGC 4861 lies in the constellation of Canes Venatici at a distance of about 22.8 million light-years from Earth.
Also known as LEDA 44536 and SDSS J125901.91+345121.4, NGC 4861 was discovered on May 1, 1785, by the English astronomer William Herschel.
Astronomers are still debating on how to classify NGC 4861.
While its physical properties indicate it to be a spiral galaxy, its appearance looks more like a comet with its dense, luminous ‘head’ and dimmer ‘tail’ trailing behind — features more fitting with an irregular dwarf galaxy.
Although small and messy, galaxies like NGC 4861 provide scientists with interesting opportunities for study.
Dwarf galaxies have lower gravitational potentials, which means that it takes less energy to move stuff about inside them than it does in other galaxies.
As a result, moving in, around, and through such a small galaxy is quite easy to do, making them far more likely to be suffused with streams and outflows of speedy charged particles known as galactic winds, which can flood such galaxies with little effort.
These galactic winds can be powered by the ongoing process of star formation, which involves huge amounts of energy.
New stars are springing into life within the bright, colorful ‘head’ of NGC 4861 and ejecting streams of high-speed particles as they do so, which flood outwards to join the wider galactic wind.
While NGC 4861 would be a perfect candidate to study such winds, recent studies did not find any galactic winds in it.
This image of NGC 4861 is a composite of separate exposures acquired by Hubble’s Advanced Camera for Surveys (ACS) and Wide Field Camera 3 (WFC3).
Four filters — the broad V-band filter F606W, the near-infrared filter F814W, red filters F658N and F673N — were used to sample various wavelengths.
The color results from assigning different hues to each monochromatic image associated with an individual filter.
