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What are the types of galaxies

Galaxies are certainly among the most popular telescope targets for amateur astronomers. They show an incredibly

wide range of size, shape, and internal structure has undoubtedly lead to their fascination among both amateurs and

professional astronomers alike. they are vast groups of stars, dust, and gas ranging from a few thousand to nearly a

million light-years in diameter. Their respective masses show a similarly broad range from less than a million to

well over trillion solar masses. This variety of shape and form is far greater than in any other class of deep sky

objects.

Elliptical GalaxiesElliptical galaxy is a galaxy that is elliptical in "observed shape". they are generally composed of only old stars, with

little dense gas available for additional star formation. Dynamical measurements show that many are tri-axial,

geometric figures with different radii along each axis, and thus their shapes reflect the distribution of stellar orbits

rather than being produced by a net rotation. In the "Hubble Classification", ellipticals are described according to

apparent shape, from E0 for circular images to E7 for the most flattenedellipticals.Elliptical galaxies span a vast

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range in size and luminosity, from 100 million stars in a dwarf elliptical to10 million million in the largest

giant ellipticals.

Famous Examples:

M32 (NGC 221) about 2.65 million light-years away in the constellation Andromeda.

M49 (NGC 4472) about 49 million light-years away in the constellation Virgo.

M59 (NGC 4621) about 60 million light-years away in the constellation Virgo.

M60 (NGC 4649) approximately 55 million light-years away in the constellation Virgo.

M87 (Virgo A or NGC 4486) a super giant elliptical galaxy located 55 million light-years away in the constellation

Virgo.

M89 (NGC 4552) located about 50 million light-years away in the constellation Virgo.

M105 (NGC 3379) located about 32 million light-years away in the constellation Leo.

Maffei 1(the closest giant elliptical galaxy) the closest giant elliptical galaxy to the Milky Way about 9.8 light-years

away in the constellation Cassiopeia.

Spiral GalaxiesThey are galaxies that has a thin disk of stars, gas and dust, in which a more or less continuous spiral pattern

appears. Most spiral galaxies also contain a central spherical bulge of old stars. The spiral pattern may be maintained

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as a "DENSITY WAVE" moving through the disk, or by differential rotation shearing star-forming regions into

locally tilted segments. Thus spirals range from grand design patterns, with between two and four arms traceable

through complete turns around the galaxy, to flocculent galaxies, in which only small,discontinuous pieces of the

spiral pattern exist. Most spiral galaxies have at least a weak bar, an elongation of the nuclear bulge, in the plane of 

the disk. Spirals are classified into various subtypes in the "Hubble Classification". Most maintain active star

formation and have a significant reservoir of interstellar gas to fuel additional generations of stars.

Famous Examples:

Triangulum Galaxy (M33 or NGC 598) about 3 million light years away in the constellation Triangulum.

Andromeda Galaxy (M31 or NGC 224) about 2.5 million light-years away in the constellation Andromeda.

Sunflower Galaxy (M63 or NGC 5055) about 37 light years away in the constellation Canes Venatici.

Whirlpool Galaxy (M51a or NGC 5194) an interacting spiral galaxy located at a distance of approximately 23

million light years in the constellation Canes Venatici.

Pinwheel Galaxy (M101 or NGC 5457) a face-on spiral galaxy distanced 25 million light years away in the

constellation Ursa Major.

This image shows the evolution of spiral galaxies, from fully formed structures to disheveled

collections of stars just beginning to form. These galaxies were captured in the GreatObservatories Origins Deep Survey and are presented in the IMAX short film "Hubble: GalaxiesAcross Space and Time." It takes billions of years for the light of a distant galaxy to reach Earth.

Consequently, we see such galaxies as they were in the past, and can thus assemble a rough

pictorial history of galaxy evolution. Credit: NASA, ESA, F. Summers and Z. Levay (STScI).  

Hubble Space Telescope and NASA's Spitzer Space Telescope joined forces to create this

striking composite image of one of the most popular sights in the universe. Messier 104 iscommonly known as the Sombrero galaxy. 

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Barred spiral galaxiesIt is a spiral galaxy in which the distribution of stars near the nucleus is elongated in the disk plane.

Strong bars are reflected in the Hubble Classification. Weaker bars are common among spirals,

with thede Vaucouleurstypes indicating that about 60% of spiral shave distinct bars. Infrared

observations, less sensitive to dust absorption and the confusing influence of young stars, may indicate

an even greater fraction of spirals with small or weak bars, among them our Galaxy. Stellar dynamics in a

disk can produce a bar because of instabilities,and a bar in turn may dissolve into a ring structure over

cosmic time. Indeed, many bars are accompanied by stellar rings. Bars can alter the chemical content of

a galaxy’s gas, since flow along the bar mixes gas originally located at a wide range of radii, which thus

started with different chemical compositions.

Famous Examples:

NGC 4314, a barred spiral galaxy approximately 40 million light years away in the constellation

Coma Berenices.

NGC 4921, a barred spiral galaxy in the Coma Cluster, located in the constellation Coma Berenices about

320 million light years away.

M95 (NGC 3351), a barred spiral galaxy about 33 million light years away in the constellation Leo.

NGC 3953, a barred spiral galaxy located in the constellation Ursa Major at a distance of 46 million light

years away.

NGC 2903, a barred spiral galaxy about 30 million light-years away in the constellation Leo.

M108 (NGC 3556), a barred spiral galaxy in the constellation Ursa Major.

M58 (NGC 4579), a barred spiral galaxy in the constellation Virgo, approximately 68 million light-years

away.

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The barred spiral galaxy, NGC 3953

The barred spiral galaxy, NGC 2903