NGC 1427A is an

irregular galaxy An irregular galaxy is a galaxy that does not have a distinct regular shape, unlike a spiral or an elliptical galaxy. Irregular galaxies do not fall into any of the regular classes of the Hubble sequence, and they are often chaotic in appearanc ...

in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Fornax Fornax () is a constellation in the southern celestial hemisphere, partly ringed by the celestial river Eridanus. Its name is Latin for furnace. It was named by French astronomer Nicolas Louis de Lacaille in 1756. Fornax is one of the 88 modern ...

. Its

distance modulus The distance modulus is a way of expressing distances that is often used in astronomy. It describes distances on a logarithmic scale based on the astronomical magnitude system. Definition The distance modulus \mu=m-M is the difference between the ...

has been estimated using the

globular cluster luminosity function A globular cluster is a spheroidal conglomeration of stars. Globular clusters are bound together by gravity, with a higher concentration of stars towards their centers. They can contain anywhere from tens of thousands to many millions of memb ...

to be 31.01 ± 0.21 which is about 52 Mly. It is the brightest dwarf irregular member of the

Fornax cluster The Fornax Cluster is a cluster of galaxies lying at a distance of 19 megaparsecs (62 million light-years). It has an estimated mass of solar masses, making it the second richest galaxy cluster within 100 million light-years, after the consider ...

and is in the foreground of the cluster's central galaxy

NGC 1399 NGC 1399 is a large elliptical galaxy in the Southern constellation Fornax (constellation), Fornax, the central galaxy in the Fornax Cluster. The galaxy is 66 million light-years away from Earth. With a diameter of 130 000 light-years, it is ...

Characteristics and fate

NGC 1427A is over 20,000 light-years long and similar to the

Large Magellanic Cloud The Large Magellanic Cloud (LMC), or Nubecula Major, is a satellite galaxy of the Milky Way. At a distance of around 50 kiloparsecs (≈160,000 light-years), the LMC is the second- or third-closest galaxy to the Milky Way, after the ...

. The resulting pressure is giving the galaxy its arrowhead outline and triggering the beautiful but violent episodes of star formation. Under the influence of

galactic tide A galactic tide is a tidal force experienced by objects subject to the gravitational field of a galaxy such as the Milky Way. Particular areas of interest concerning galactic tides include galactic collisions, the disruption of dwarf or satellit ...

s, NGC 1427A is travelling into the center of the Fornax cluster with a velocity of approximately 600 km per second. Its distinctive arrowhead shape has been formed by this rapid, upwards movement. The interaction of NGC 1427A with Fornax gasses and galaxies during its journey will cause the disruption of the galaxy within the next billion years, an event which was common during the evolution of the Universe but has become increasingly rare.

Image

The Hubble Space Telescope's Advanced Camera for Surveys was used to obtain images of NGC 1427A in visible (green), red, and infrared filters in January 2003. These images were then combined by the Hubble Heritage team to create the color image shown in box. Astronomers are using the data to investigate the star-formation patterns throughout the object, to verify a prediction that there should be a relation between the ages of stars and their positions within the galaxy. This will help them understand how the gravitational influence of the cluster has affected the internal workings of this galaxy, and how this galaxy has responded to passing through the cluster environment. This image was image of the day on March 4, 2005.

Background spiral galaxy

To the upper left of NGC 1427A is a background galaxy that happens to lie near Hubble's line of sight but is some 25 times further away, about 1.3 billion light-years away. In contrast to the irregularly shaped NGC 1427A, the background galaxy is a magnificent spiral, somewhat similar to our own

Milky Way The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye ...

. Stars are forming in its symmetric pinwheel-shaped spiral arms, which can be traced into the galaxy's bright nucleus. This galaxy is, however, less dominated by very young stars than NGC 1427A, giving it an overall yellower color. At even greater distances background galaxies of various shapes and colors are scattered across the Hubble image.

References

External links

* {{DEFAULTSORT:NGC 1427A Barred irregular galaxies Fornax 1427A 13500