Deep-Sky Objects in Pisces

CGCG 436-030
Credit: Interacting spiral galaxies (CGCG 436 - 030) by NASA, ESA, the Hubble Heritage and A. Evans

Pisces is the 14th biggest constellations in the night sky, and the 4th biggest of the zodiac constellations, taking up an area of 889.417 square degrees of the northern sky, between latitudes +90° and -65°. The brightest star in Pisces is Eta Piscium, a magnitude +3.62 yellow giant located about 294 light years from Earth that also has a faint companion found about one second of arc away from the primary star.

Pisces is best seen during the month of November in an area of the sky known as “Water”, or sometimes “The Sea”, along with other watery themed constellations, such as Capricornus (Sea Goat), Aquarius (Water [or Cup] Bearer, Cetus (Whale), Delphinus (Dolphin), Eridanus (Great River), and Hydra (Water Serpent).

Apart from several prominent asterisms, including the North Fish (Piscis Boreus), the North Cord (Linum Boreum), the South Cord (Linum Austrinum), the South Fish (Piscis Austrinus), The Circlet, and the Turtle, Pisces contains one Messier object called M74, together with several other deep-sky objects, the most notable of which are briefly described in this list.

Messier 74 (M74, NGC 628)

Messier 74M74 is located about 30 million light years away, with its 100 billion stars shining with a combined apparent visual magnitude of +10.0. Even though M74 is regarded as a classic example of a grand-design spiral galaxy, it has a very low surface brightness, which makes it one of the most difficult Messier objects to observe with amateur equipment. Look for M74 about 1.5 degrees to the east-northeast of the star Eta Piscium.

Of the two supernova events (SN 2002ap in 2002 and SN2003gd in 2003) that have been observed in M74, SN2002ap was the more energetic, and is considered to have been a rare Type Ic supernovae, also known as a hypernova, which are thought to be the most energetic explosions since the Big Bang. In 2005, an X-ray source that is more luminous than any observed neutron star was discovered in the galaxy, and while there is some doubt as to the exact nature of this source, which is designated CXOU J013651.1+154547, most investigators believe that it is an intermediate-mass black hole with a mass of about 10 000 Suns.

CGCG 436-030 (PGC 4798)

The interacting galaxies shown at the top of this post are located about 400 million light years away, with the most notable aspect of this pair being the curling tail stretching from the larger galaxy, and the several tails extending from the smaller galaxy below it. The tails are the result of the gravitational effects the galaxies have on each other, while the bright object between the two galaxies is a foreground star within the Milky Way galaxy.

CL 0024+1654

CL 0024+1654

The galaxy cluster CL 0024, which consists mainly of yellow elliptical and spiral galaxies, is located about 3.6 billion light years from our solar system. The designation 1654 refers to a galaxy located about 5.7 billion light years away, and situated behind the cluster, whose light is being focused and distorted by the cluster in a process known as gravitational lensing.

While the blue arcs in this image (including the blue smear near the centre of the cluster) represent several images of the gravitationally focused 1654, a recent study using advanced analytical methods has revealed that at least 33 images of other galaxies located behind the cluster are also present.

NGC 520

NGC 520This pair of disk galaxies started the process of merging about 300 million years ago, and the pair represents the intermediate stages of the merging process, since the two galactic nuclei are still separate. The weird looking “arms” that give the pair of galaxies the appearance of a cross are the disks of the galaxies that still retain some of their original shape.

NGC 520 is one of the brightest galaxy pairs in the entire night sky, and is an easy target for small telescopes under dark skies. The pair is located about 100 million light years away, and strongly resembles the shape of a comet in telescopic views. NCG 520 is also listed as Arp 157 in Arp’s catalogue of peculiar galaxies.

NGC 60

NGC 60This artists’ impression of the spiral galaxy NGC 60 is based on data taken from the 2MASS survey, which failed to solve the mystery of the severely distorted arms of the galaxy. This type of distortion is always caused by gravitational interactions with another galaxy, but in the case of NGC 60, there is no other galaxies close enough to explain the shape of the galaxy’s arms. To date, the mystery remains unresolved. NGC 60 is located about 500 million light years away, and has an apparent visual magnitude of +14.85.


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