Andromeda Galaxy



The Andromeda Galaxy, also known as Messier 31, M31, or NGC 224; often referred to as the Great Andromeda Nebula in older texts, is often referred to as the Great Andromeda Nebula in older texts.

Andromeda is the nearest spiral galaxy to the Milky Way, but not the closest galaxy overall. It gets its name from the area of the sky in which it appears, the Andromeda constellation, which was named after the mythological princess Andromeda. Andromeda is the largest galaxy of the Local Group, which consists of the Andromeda Galaxy, the Milky Way Galaxy, the Triangulum Galaxy, and about 30 other smaller galaxies. Although the largest, Andromeda may not be the most massive, as recent findings suggest that the Milky Way contains more dark matter and may be the most massive in the grouping.

The 2006 observations by the Spitzer Space Telescope revealed that M31 contains one trillion (1012) stars, more than the number of stars in our own galaxy, which is estimated to be c. 200-400 billion. While the 2006 estimates put the mass of the Milky Way to be 80% of the mass of Andromeda, which is estimated to be 7.1 X 1011 solar masses, a 2009 study concluded that Andromeda and the Milky Way are about equal in mass. The Andromeda Galaxy and the Milky Way are expected to collide in perhaps 4.5 billion years.

At an apparent magnitude of 3.4, the Andromeda Galaxy is notable for being one of the brightest Messier objects, making it visible to the naked eye on moonless nights even when viewed from areas with moderate light pollution. Although it appears more than six times as wide as the full Moon when photographed through a larger telescope, only the brighter central region is visible to the naked eye or when viewed using a binoculars or a small telescope.




Observation History

The earliest recorded observation of the Andromeda Galaxy was in 964 CE by the Persian astronomer, Abd al-Rahman al-Sufi (Azophi), who described it as a "small cloud" in his Book of Fixed Stars. Other star charts of that period have it labeled as the Little Cloud.

The first description of the object based on telescopic observation was given by Simon Marius in 1612.

Charles Messier catalogued it as object M31 in 1764 and incorrectly credited Marius as the discoverer, unaware of Al Sufi's earlier work.

In 1785, the astronomer William Herschel noted a faint reddish hue in the core region of the M31. He believed it to be the nearest of all the "great nebulae" and, based on the color and magnitude of the nebula, he incorrectly guessed that it was no more than 2,000 times the distance of Sirius.

William Huggins in 1864 observed the spectrum of M31 and noted that it differed from a gaseous nebula. The spectra of M31 displayed a continuum of frequencies, superimposed with dark absorption lines that help identify the chemical composition of an object. The Andromeda nebula was very similar to the spectra of individual stars, and from this it was deduced that M31 had a stellar nature.

In 1885, a supernova (known as "S Andromedae") was seen in M31, the first and so far only one observed in that galaxy. At the time M31 was considered to be a nearby object, so the cause was thought to be a much less luminous and unrelated event called a nova, and was named accordingly "Nova 1885".

The first photographs of M31 were taken in 1887 by Isaac Roberts from his private observatory in Sussex, England. The long-duration exposure allowed the spiral structure of the galaxy to be seen for the first time. However, at the time this object was commonly believed to be a nebula within our galaxy, and Roberts mistakenly believed that M31 and similar spiral nebulae were actually solar systems being formed, with the satellites nascent planets.

The radial velocity of this object with respect to our solar system was measured in 1912 by Vesto Slipher at the Lowell Observatory, using spectroscopy. The result was the largest velocity recorded at that time, at 300 kilometres per second (190 mi/s), moving in the direction of the Sun.




Island Universe

In 1917, Heber Curtis observed a nova within M31. Searching the photographic record, 11 more novae were discovered. Curtis noticed that these novae were, on average, 10 magnitudes fainter than those that occurred within our Galaxy. As a result he was able to come up with a distance estimate of 500,000 light-years (3.2X1010 AU). He became a proponent of the so-called "island universes" hypothesis, which held that spiral nebulae were actually independent galaxies.

In 1920 the Great Debate between Harlow Shapley and Heber Curtis took place, concerning the nature of the Milky Way, spiral nebulae, and the dimensions of the universe. To support his claim that Great Andromeda Nebula (M31) was an external galaxy, Curtis also noted the appearance of dark lanes resembling the dust clouds in our own Galaxy, as well as the significant Doppler shift.

In 1922 Ernst Opik presented a very elegant and simple astrophysical method to estimate the distance of M31, his result (450 kpc (1,500 kly)) put Andromeda Nebula far outside our Galaxy.

Edwin Hubble settled the debate in 1925 when he identified extragalactic Cepheid variable stars for the first time on astronomical photos of M31. These were made using the 2.5 metres (98 in) Hooker telescope, and they enabled the distance of Great Andromeda Nebula to be determined. His measurement demonstrated conclusively that this feature was not a cluster of stars and gas within our Galaxy, but an entirely separate galaxy located a significant distance from our own.

Andromeda plays an important role in galactic studies, since it is the nearest spiral galaxy (although not the nearest galaxy).

In 1943, Walter Baade was the first person to resolve stars in the central region of the Andromeda Galaxy. Based on his observations of this galaxy, he was able to discern two distinct populations of stars based on their metallicity, naming the young, high velocity stars in the disk Type I and the older, red stars in the bulge Type II. This nomenclature was subsequently adopted for stars within the Milky Way, and elsewhere. (The existence of two distinct populations had been noted earlier by Jan Oort.) Dr. Baade also discovered that there were two types of Cepheid variables, which resulted in a doubling of the distance estimate to M31, as well as the remainder of the Universe.

Radio emission from the Andromeda Galaxy was first detected by Grote Reber in 1940. The first radio maps of the galaxy were made in the 1950s by John Baldwin and collaborators at the Cambridge Radio Astronomy Group. The core of the Andromeda Galaxy is called 2C 56 in the 2C radio astronomy catalogue.

In 2009, the first planet may have been discovered in the Andromeda Galaxy. This candidate was detected using a technique called microlensing, which is caused by the deflection of light by a massive object.




Structure

Based on its appearance in visible light, the Andromeda galaxy is classified as an SA(s)b galaxy in the de Vaucouleurs-Sandage extended classification system of spiral galaxies. However, data from the 2MASS survey showed that the bulge of M31 has a box-like appearance, which implies that the galaxy is actually a barred galaxy with the bar viewed almost directly along its long axis.

In 2005, astronomers used the Keck telescopes to show that the tenuous sprinkle of stars extending outward from the galaxy is actually part of the main disk itself. This means that the spiral disk of stars in Andromeda is three times larger in diameter than previously estimated. This constitutes evidence that there is a vast, extended stellar disk that makes the galaxy more than 220,000 light-years (67,000 pc) in diameter. Previously, estimates of Andromeda's size ranged from 70,000 to 120,000 light-years (21,000 to 37,000 pc) across.

The galaxy is inclined an estimated 77° relative to the Earth (where an angle of 90° would be viewed directly from the side). Analysis of the cross-sectional shape of the galaxy appears to demonstrate a pronounced, S-shaped warp, rather than just a flat disk. A possible cause of such a warp could be gravitational interaction with the satellite galaxies near M31. The galaxy M33 could be responsible for some warp in M31's arms, though more precise distances and radial velocities are required.

Spectroscopic studies have provided detailed measurements of the rotational velocity of M31 at various radii from the core. In the vicinity of the core, the rotational velocity climbs to a peak of 225 kilometres per second (140 mi/s) at a radius of 1,300 light-years (82,000,000 AU) light-years, then descends to a minimum at 7,000 light-years (440,000,000 AU) where the rotation velocity may be as low as 50 kilometres per second (31 mi/s).

Thereafter the velocity steadily climbs again out to a radius of 33,000 light-years (2.1x109 AU), where it reaches a peak of 250 kilometres per second (160 mi/s). The velocities slowly decline beyond that distance, dropping to around 200 kilometres per second (120 mi/s) at 80,000 light-years (5.1x109 AU). These velocity measurements imply a concentrated mass of about 6 x 109 M in the nucleus. The total mass of the galaxy increases linearly out to 45,000 light-years (2.8 x109 AU), then more slowly beyond that radius.

The spiral arms of Andromeda are outlined by a series of H II regions that Baade described as resembling "beads on a string". They appear to be tightly wound, although they are more widely spaced than in our galaxy.

Rectified images of the galaxy show a fairly normal spiral galaxy with the arms wound up in a clockwise direction. There are two continuous trailing arms that are separated from each other by a minimum of about 13,000 light-years (8.2E+8 AU). These can be followed outward from a distance of roughly 1,600 light-years (100,000,000 AU) from the core. The most likely cause of the spiral pattern is thought to be interaction with M32. This can be seen by the displacement of the neutral hydrogen clouds from the stars.

In 1998, images from the European Space Agency's Infrared Space Observatory demonstrated that the overall form of the Andromeda galaxy may be transitioning into a ring galaxy. The gas and dust within Andromeda is generally formed into several overlapping rings, with a particularly prominent ring formed at a radius of 32,000 light-years (2.0x109 AU) from the core. This ring is hidden from visible light images of the galaxy because it is composed primarily of cold dust.

Close examination of the inner region of Andromeda showed a smaller dust ring that is believed to have been caused by the interaction with M32 more than 200 million years ago. Simulations show that the smaller galaxy passed through the disk of Andromeda along the latter's polar axis. This collision stripped more than half the mass from the smaller M32 and created the ring structures in Andromeda.

Studies of the extended halo of M31 show that it is roughly comparable to that of the Milky Way, with stars in the halo being generally "metal-poor", and increasingly so with greater distance. This evidence indicates that the two galaxies have followed similar evolutionary paths. They are likely to have accreted and assimilated about 1-200 low-mass galaxies during the past 12 billion years. The stars in the extended halos of M31 and the Milky Way may extend nearly one third the distance separating the two galaxies.




Nucleus

M31 is known to harbor a dense and compact star cluster at its very center. In a large telescope it creates a visual impression of a star embedded in the more diffuse surrounding bulge. The luminosity of the nucleus is in excess of the most luminous globular clusters.

In 1991 Tod R. Lauer used WFPC, then on board the Hubble Space Telescope, to image Andromeda's inner nucleus. The nucleus consists of two concentrations separated by 1.5 parsecs (4.9 ly). The brighter concentration, designated as P1, is offset from the center of the galaxy. The dimmer concentration, P2, falls at the true center of the galaxy and contains a 3-5x107 M black hole.

Scott Tremaine has proposed that the observed double nucleus could be explained if P1 is the projection of a disk of stars in an eccentric orbit around the central black hole. The eccentricity is such that stars linger at the orbital apocenter, creating a concentration of stars. P2 also contains a compact disk of hot, spectral class A stars. The A stars are not evident in redder filters, but in blue and ultraviolet light they dominate the nucleus, causing P2 to appear more prominent than P1.

While at the initial time of its discovery it was hypothesized that the brighter portion of the double nucleus was the remnant of a small galaxy "cannibalized" by Andromeda, this is no longer considered to be a viable explanation. The primary reason is that such a nucleus would have an exceedingly short lifetime due to tidal disruption by the central black hole. While this could be partially resolved if P1 had its own black hole to stabilize it, the distribution of stars in P1 does not suggest that there is a black hole at its center.

Artist's concept of Andromeda galaxy core showing a view across a

mysterious disk of young, blue stars encircling a supermassive black hole.




Discrete Sources

Multiple X-ray sources have been detected in the Andromeda Galaxy, using observations from the ESA's XMM-Newton orbiting observatory. Robin Barnard et al. hypothesized that these are candidate black holes or neutron stars, which are heating incoming gas to millions of kelvins and emitting X-rays. The spectrum of the neutron stars is the same as the hypothesized black holes, but can be distinguished by their masses.

There are approximately 460 globular clusters associated with the Andromeda galaxy. The most massive of these clusters, identified as Mayall II, nicknamed Globular One, has a greater luminosity than any other known globular cluster in the local group of galaxies.

It contains several million stars, and is about twice as luminous as Omega Centauri, the brightest known globular cluster in the Milky Way. Globular One (or G1) has several stellar populations and a structure too massive for an ordinary globular. As a result, some consider G1 to be the remnant core of a dwarf galaxy that was consumed by M31 in the distant past. The globular with the greatest apparent brightness is G76 which is located in the south-west arm's eastern half.

In 2005, astronomers discovered a completely new type of star cluster in M31. The new-found clusters contain hundreds of thousands of stars, a similar number of stars that can be found in globular clusters. What distinguishes them from the globular clusters is that they are much larger - several hundred light-years across - and hundreds of times less dense. The distances between the stars are, therefore, much greater within the newly discovered extended clusters.




Future Collision of the Milky Way with Andromeda

The Andromeda Galaxy is approaching the Sun at about 100 to 140 kilometres per second (62 to 87 mi/s), so it is one of the few blue shifted galaxies. The Andromeda Galaxy and the Milky Way are thus expected to collide in perhaps 2.5 billion years, although the details are uncertain since Andromeda's tangential velocity with respect to the Milky Way is only known to within about a factor of two.

A likely outcome of the collision is that the galaxies will merge to form a giant elliptical galaxy. Such events are frequent among the galaxies in galaxy groups. The fate of the Earth and the Solar System in the event of a collision are presently unknown. If the galaxies do not merge, there is a small chance that the Solar System could be ejected from the Milky Way or join Andromeda.




Andromeda's Satellite Galaxies  Wikipedia
Like the Milky Way, Andromeda Galaxy has satellite galaxies, consisting of 14 known dwarf galaxies.




In the News ...


Andromeda Heavier Than Milky Way   National Geographic - July 30, 2014
Looks like our home galaxy, the Milky Way, has gone on the ultimate weight-loss program, according to astronomers. According to a new supercomputer simulation, it turns out that the entire mass of our Milky Way galaxy is about half that of the great Andromeda galaxy, our nearest neighboring spiral galaxy some 2.6 million light-years away from us. Astronomers had long thought the galaxies were twins.




  The life cycle of Andromeda's stars   MSNBC - April 28, 2011

No doubt, naked-eye views of the universe are spectacular, but there's much more going on out there than appears in visible light. That's why astronomers routinely observe with a variety of telescopes equipped to capture multiple wavelengths of light across the electromagnetic spectrum.




Andromeda's Jewel in 'Invisible' Light   Discovery - April 28, 2011

It was only in the 20th century that astronomers made a concerted effort to look at the "invisible universe," or study the universe with light that our eyes cannot detect. This new animation from the European Space Agency celebrates this quest for the invisible as we look at our nearest big galaxy, Andromeda, or Messier 31, in microwave, infrared, optical, ultraviolet, and x-ray light. Slowly, the infrared observations come into view. Since we do not see infrared, we have to choose a color with which to represent it. The galaxy looks flat now, with sharper spiral arms and not much activity in the center.

The infrared light is not from stars, but is the glow of dust particles within the busy traffic-jams that are the star-forming spiral structures of such a galaxy. In particular, we are looking at cool dust, which tends not to be in the even busier central bulge of the galaxy. Then, we swing on over to the x-ray light, where it no longer looks like a spiral galaxy, but a cluster of points of various sizes. Many of these represent the endpoints of the lives of massive stars that have long since exploded and left behind cold-dead remnants. Well, almost dead, as interactions with their environment can cause these remnants, such as neutron stars and black holes, to give off lots of energy in the form of these x-rays. X-ray sources in Andromeda have even been seen to vary in brightness over the span of several years.




Astronomers identify thick disc of older stars in nearby Andromeda galaxy   PhysOrg - February 15, 2011

An international team of astronomers has identified for the first time a thick stellar disc in the Andromeda galaxy, the nearest large spiral galaxy to our own Milky Way.




  Andromeda 'born in a collision'   BBC - November 25, 2010
The nearest spiral galaxy to the Milky Way - Andromeda - was born when two smaller galaxies collided, say astronomers. An international team conducted a computer simulation of how Andromeda evolved over time. The results suggest that two galaxies collided some nine billion years ago and permanently fused about 5.5 billion years ago.




New tidal streams found in Andromeda reveal history of galactic mergers   PhysOrg - January 7, 2010
An international team of astronomers has identified two new tidal streams in the Andromeda galaxy, the remnants of dwarf galaxies consumed by our large galactic neighbor. Analysis of the stars in Andromeda's tidal streams and other components of its extended halo is yielding new insights into the processes involved in the formation and evolution of massive galaxies.




Andromeda galaxy appears to have expanded by digesting stars from other galaxies   BBC - September 3, 2009

The vast Andromeda galaxy appears to have expanded by digesting stars from other galaxies, research has shown. When an international team of scientists mapped Andromeda, they discovered stars that they said were "remnants of dwarf galaxies". This consumption of stars has been suggested previously, but the team's ultra-deep survey has provided detailed images to show that it took place. This shows the "hierarchical model" of galaxy formation in action. The model predicts that large galaxies should be surrounded by relics of smaller galaxies they have consumed.




Andromeda Island Universe NASA - January 24, 2008

The most distant object easily visible to the unaided eye is M31, the great Andromeda Galaxy some two and a half million light-years away. But without a telescope, even this immense spiral galaxy - spanning over 200,000 light years - appears as a faint, nebulous cloud in the constellation Andromeda. In contrast, a bright yellow nucleus, dark winding dust lanes, gorgeous blue spiral arms and star clusters are recorded in this stunning telescopic digital mosaic. While even casual skygazers are now inspired by the knowledge that there are many distant galaxies like M31, astronomers seriously debated this fundamental concept less than 90 years ago. Were these "spiral nebulae" simply outlying components of our own Milky Way Galaxy or were they instead "island universes" -- distant systems of stars comparable to the Milky Way itself? This question was central to the famous Shapley-Curtis debate of 1920, which was later resolved by observations of M31 in favor of Andromeda, island universe.




Astronomers discover an enormous halo of red giant stars around Andromeda BBC - January 8, 2007

Astronomers have found an enormous halo of stars around the Andromeda galaxy. The discovery suggests the nearby spiral galaxy, also known as M31, is as much as five times bigger than astronomers had previously thought. In fact, Andromeda's "suburbs" are so vast that they nearly overlap with those of our own Milky Way galaxy. Andromeda is a spiral galaxy similar to the Milky Way. About 2.5 million light-years away from Earth, it is the largest galaxy in the "local group", which also includes the Milky Way and about 30 smaller galaxies.




Collision Created Rings Around Andromeda Space.com - October 18, 2006

Infrared photographs taken with NASA’s Spitzer Space Telescope revealed a never-before-seen dust ring deep within the Andromeda galaxy. When combined with a previously observed outer ring, the presence of both dust rings suggests that M32 plunged through the disk of Andromeda along Andromeda’s polar axis approximately 210 million years ago.




Lady in Red: Andromeda Galaxy Shines in Spitzer's Eyes PhysOrg - October 14, 2005

Andromeda is the most-studied galaxy outside our own Milky Way, yet Spitzer's sensitive infrared eyes have detected captivating new features, including bright, aging stars and a spiral arc in the center of the galaxy. The infrared image also reveals an off-centered ring of star formation and a hole in the galaxy's spiral disk of arms. These asymmetrical features may have been caused by interactions with the several satellite galaxies that surround Andromeda. Occasionally small satellite galaxies run straight through bigger galaxies. It appears a little galaxy punched a hole through Andromeda's disk, much like a pebble breaks the surface of a pond.

Approximately 2.5 million light-years away, Andromeda is the closest spiral galaxy and is the only one visible to the naked eye. Unlike our Milky Way galaxy, which we view from the inside, Andromeda is studied from the outside. Astronomers believe that Andromeda and the Milky Way will eventually merge together.

Spitzer detects dust heated by stars in the galaxy. Its multiband imaging photometer's 24-micron detector recorded approximately 11,000 separate infrared snapshots over 18 hours to create the new comprehensive mosaic. This instrument's resolution and sensitivity is a vast improvement over previous infrared technologies, enabling scientists to trace the spiral structures within Andromeda to an unprecedented level of detail.




Mysterious Stars Surround Andromeda's Black Hole Space.com - September 21, 2005

Stars race around a black hole at the center of the Andromeda galaxy so fast that they could go the distance from Earth to the Moon in six minutes. The finding, announced today, solves a mystery over the source of strange blue light coming from Andromeda's center. But it generates a new puzzle: The stars' phenomenal orbital velocity suggests they should never have formed in the first place. Astronomers first spotted the blue light near Andromeda's core in 1995. Three years later, another group determined that the light emanated from a cluster of hot, young stars. Nobody knew how many were involved.




Mysterious ring of stars guards Andromeda's heart New Scientist - September 21, 2005

The Milky Way's near-twin galaxy, Andromeda, harbors a supermassive black hole at its core that is surrounded by an unexpected and unexplained disc of young stars. These new observations by the Hubble Space Telescope answer one longstanding mystery: the source of bright blue light very close to the spiral galaxy's central black hole, first spotted using Hubble a decade ago. Yet solving this mystery has immediately created another in its place. The newly discovered disc is composed of over 400 very hot, young blue stars, orbiting like a planetary system very close to the black hole. That puzzles astronomers because the black hole's intense gravitational field should have torn apart any clouds of matter long before they could coalesce to form new stars. The stars form a very flat disc that is only one light year across. An elliptical disc of older red stars surrounds it, spanning about five light years. Since the two discs appear to be in the same plane, they are probably related, but no one yet understands how either disc came into being. View an animation of how the two discs of stars might look, in Quicktime, or Mpeg format.




Andromeda in Mythology



Andromeda is a princess from Greek mythology who, as divine punishment for her mother's bragging, (the Boast of Cassiopeia) was chained to a rock as a sacrifice to a sea monster. She was saved from death by Perseus, her future husband. Her name is the Latinized form of the Greek. The subject has been popular in art since classical times. In the Christian period the subject was converted into the legend of St George and the Dragon, but from the Renaissance interest revived in the original story, typically as derived from Ovid's account.

In Greek mythology, Andromeda was the daughter of Cepheus and Cassiopeia, king and queen of the kingdom Ethiopia.

Her mother Cassiopeia boasted that she was more beautiful than the Nereids, the nymph-daughters of the sea god Nereus and often seen accompanying Poseidon. To punish the Queen for her arrogance, Poseidon, brother to Zeus and god of the sea, sent a sea monster (Cetus) to ravage the coast of Ethiopia including the kingdom of the vain Queen. The desperate King consulted the Oracle of Apollo, who announced that no respite would be found until the king sacrificed his virgin daughter Andromeda to the monster. She was chained naked to a rock on the coast.

Perseus was returning from having slain the Gorgon Medusa, he found Andromeda and slew Cetus by approaching invisible with Hades's helm and slaying him. He set her free, and married her in spite of Andromeda having been previously promised to her uncle Phineus. At the wedding a quarrel took place between the rivals, and Phineus was turned to stone by the sight of the Gorgon's head (Ovid, Metamorphoses v. 1).

Andromeda followed her husband to Tiryns in Argos, and together they became the ancestors of the family of the Perseidae through the line of their son Perses. Perseus and Andromeda had seven sons: Perseides, Perses, Alcaeus, Heleus, Mestor, Sthenelus, and Electryon, and one daughter, Gorgophone. Their descendants ruled Mycenae from Electryon down to Eurystheus, after whom Atreus attained the kingdom, and would also include the great hero Heracles. According to this mythology, Perseus is the ancestor of the Persians.

After her death, Andromeda was placed by Athena amongst the constellations in the northern sky, near Perseus and Cassiopeia. The constellation had been named after her.




Andromeda Constellation


Andromeda is a constellation in the northern sky.

It is named after Andromeda, the princess in the Greek legend of Perseus who was chained to a rock to be eaten by sea monster Cetus. It is sometimes called "the Chained Lady" or "the Chained Woman" in English. It has also been called Persea (Perseus's wife) or Cepheis (Cepheus's daughter).


Stars and Other Objects

The binary gamma And gives splendid view even in smaller telescopes for the two components can easily be separated. The brighter component has mag 2.2 whereas the fainter shows a brightness of mag 5.0 . As they are of different color they certainly make a showpiece of a double in the sky.

The 56 And. is a fainter pair, both being of 6th magnitude.

The planetary nebula NGC 7662 is one of the easiest to view with smaller amateur instruments. Using a high magnification it reveals a fuzzy blue-green elliptical disk.

The stars of the open star cluster NGC 752 are scattered over a large area. Therefore it is best viewed with binoculars. The member stars (about 100) show magnitudes between 9 and 10. NGC 752 is located near 56 And.

This constellation is best known for the Andromeda Galaxy, M31, one of the most famous objects in the sky, which can most easily be found (it can be seen even with the naked eye once you get a bit out of a lightpolluted city) and gives a brilliant view in each optical instrument. As it is the nearest spiral galaxy to us, it allows therefore an intensive study of the properties of spiral galaxies. Because we sit within our galaxy we cannot so easily observe the properties of ours but the Andromeda galaxy helps to understand our galaxy as well.

The Andromeda Galaxy has two satellites: M110 (NGC 205) and M32. M110 is located one degree northwest of M31 and M32 can be found half a degree south of M31. Both are elliptical galaxies. Detailed information to all three galaxies can be found in the Messier database about M 31, M 32 and M110.

The most famous deep sky object in Andromeda is a spiral galaxy Messier 31, the Andromeda Galaxy, one of the most distant objects visible to the naked eye (Messier 33, the Triangulum Galaxy, is slightly farther). It is an enormous spiral galaxy much like the Milky Way.

In November, the Andromedids meteor shower appears to radiate from Andromeda.

List of Stars in the Constellation Andromeda  Wikipedia





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