The Andromeda Constellation

The Andromeda Constellation.

Andromeda (And) is one of the 48 constellations listed by the 2nd-century Greco-Roman astronomer Ptolemy, and remains one of the 88 modern constellations. The Constellation is most prominent during autumn evenings in the Northern Hemisphere, along with several other constellations named for characters in the Perseus myth. Because of its northern declination, Andromeda is visible only north of 40° south latitude; for observers farther south it lies below the horizon. It is the 19th largest constellation, with an area of 722 square degrees, which equates to 1.75% of the night sky. This is over 1,400 times the size of the full moon, 55% of the size of the largest constellation, Hydra, and over 10 times the size of the smallest constellation, Crux. The neighbouring constellations are Cassiopeia, Lacerta, Pegasus, Perseus, and Triangulum. Our Galaxy, the Milky Way is reckoned to be 100,000 light years across, but the Andromeda Galaxy is twice the size. It is expected to collide with our galaxy 5 billion years later. When it does, no one on Earth will be around to see it, as our Sun would have incinerated all life on Earth.

Andromeda has three stars brighter than magnitude 3.00. Its brightest star, Alpha Andromedae (Alpheratz), is a binary star that has also been counted as a part of Pegasus, with an overall apparent visual magnitude of 2.1 and a luminosity of 96 L. It is 97 light-years from Earth, and it represents the mythological Andromeda’s head. The star’s traditional Arabic names – Alpheratz and Sirrah.

Only marginally dimmer than Alpha is Beta Andromedae (Mirach), a red giant star of type M0, located in an asterism known as the “girdle.” It is 198 light-years away, and has a magnitude of 2.06, and a luminosity of 115 L.

Gamma Andromedae (Almach) is an orange-hued bright giant star of type K3 found at the southern tip of the constellation with an overall magnitude of 2.14. Almach is a multiple star with a yellow primary of magnitude 2.3 and a blue-green secondary of magnitude 5.0, separated by 9.7 arcseconds.

Andromeda constellation has a number of stars with confirmed exoplanets. Titawin, Upsilon Andromedae (spectral class F8V), has four planets in its orbit. The triple star Kappa Andromedae (B9IVn) has one confirmed planet about 13 times the mass of Jupiter, first discovered in November 2012. The suspected variable star 14 Andromedae, also called Veritate (K0III), has a known extrasolar planet, discovered in 2008.

The Andromeda Constellation
M 31

Andromeda belongs to the Perseus family of constellations, along with Auriga, Cassiopeia, Cepheus, Cetus, Lacerta, Pegasus, Perseus, and Triangulum. It contains three Messier objects. The constellation’s most obvious deep-sky object is the spiral Andromeda Galaxy (M31 or NGC 224, also called the Great Galaxy of Andromeda). At 2.2 million light-years from Earth, it is the closest spiral galaxy to the Milky Way and one of the brightest Messier objects, and in absolute terms, it is approximately 200,000 light-years in diameter, twice the size of the Milky Way. Several fainter galaxies, including M31’s companions M110 (NGC 205) and M32 (NGC 221), as well as the more distant NGC 891 (Caldwell 23), lie within Andromeda.

NGC 7662

Another prominent planetary nebula is NGC 7662 (Caldwell 22), lying approximately three degrees southwest of Iota Andromedae at a distance of about 4,000 light-years from Earth, also called the Blue Snowball Nebula, because it appears as a faint, round, blue-green object, with an overall magnitude of 9.2. Andromeda’s most celebrated open cluster is NGC 752 (Caldwell 28) at an overall magnitude of 5.7. It is a loosely scattered cluster in the Milky Way that measures 49 arcminutes across and features approximately twelve bright stars, although more than 60 stars of approximately 9th magnitude become visible at low magnifications in a telescope. It is considered to be one of the more inconspicuous open clusters. The Andromeda Galaxy has a total of 15 satellite galaxies, with nine of these lie in a plane, which has caused astronomers to infer that they have a common origin. These satellite galaxies, like the satellites of the

NGC 752

Milky Way, tend to be older, gas-poor dwarf elliptical and dwarf spheroidal galaxies.

Each November, the Andromedids meteor shower appears to radiate from Andromeda. The shower peaks in mid-to-late November every year, but has a low peak rate of fewer than two meteors per hour. Andromedid meteors sometimes appear as red fireballs. The Andromedids had another outburst on December 3–5, 2011, the most active shower since 1885, with a maximum zenithal hourly rate of 50 meteors per hour. The 2011 outburst was linked to ejecta from Comet Biela, which passed close to the Sun in 1649. None of the meteoroids observed were associated with material from the comet’s 1846 disintegration. The observers of the 2011 outburst predicted outbursts in 2018, 2023, and 2036.

The best views of the Andromeda Constellation is in November; right ascension 0h 34m, declination 39degrees 15minutes. Visible between latitudes 90 and -40 degrees. Credits: Constellation Guide, Universe Guide, Wikipedia.

List of Notable Stars in the Andromeda Constellation: