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en.wikipedia.org/wiki/Galaxy

A galaxy is a gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter. The word galaxy is derived from the Greek galaxias ( γαλαξίας), literally "milky", a reference to the Milky Way. Galaxies range in size from dwarfs with just a few hundred million (108) stars ... The Milky Way's central black hole, known as Sagittarius A*, has a mass four ...

space-facts.com/galaxy-types

Most ellipticals contain older, low-mass stars, and because they lack a great deal of star-making gas and dust clouds, there is little new star formation occurring ...

www.flashcardmachine.com/stellar-astronomy-test4.html

Apr 17, 2012 ... Most of the new star formation in the Milky Way Galaxy is found in the ... The greatest variation in size and mass occurs in which type of galaxy?

www.britannica.com/science/galaxy/Types-of-galaxies

galaxy - Types of galaxies: Almost all current systems of galaxy classification are ... Each of these classes is subclassified into three types according to the size of the .... This is the most familiar type of Sb galaxy and is best exemplified by the giant ... type Sd. It also has been found that some of the variations noted here for Sc ...

www.aanda.org/articles/aa/full_html/2016/09/aa28442-16/aa28442-16.html

Aug 29, 2016 ... Using spectroscopic ages of Coma early-type galaxies we also find that recently ... Remarkably, about 40% of the expansion occurs within the redshift interval z ... Although major mergers involving near-equal mass galaxies are ...... 2014), but that the variation in size between these redshifts is different.

staff.on.br/jlkm/astron2e/AT_MEDIA/CH24/CHAP24AT.HTM

Even among "normal" galaxies, there is a great range of individual variation. ... The size of the bulge and the tightness of the spiral pattern are quite well correlated. .... However, most of the mass that exists in the form of elliptical galaxies is ... Dwarf ellipticals and dwarf irregulars occur in approximately equal numbers and ...

arxiv.org/pdf/1502.04709

Feb 16, 2015 ... from maximal to sub-maximal baryons occurs within or near R2.2 for low-mass disk galaxies (with ... mean mass fractions of late- and early-type galaxies are shown to be ... friction, size, and IMF variations are key ingredients for understanding these ... to-light ratios carry an uncertainty of a factor 2 at best.

arxiv.org/pdf/astro-ph/9311064

and mass to the prominent spirals which de ne the Hubble sequence. ... Rather, they are normal size disk galaxies ... A de facto selection e ect in a study of this kind is the presence of HII regions. ... Indeed, the greatest uncertainty here is in ..... the extreme variations that can occur in the iron to oxygen ratio depending on the ...

ned.ipac.caltech.edu/level5/Young/Young6_2.html

In particular, Roberts (1969) showed that the HI mass-to blue luminosity ratio, ... In particular, the late type spiral galaxies have a lower global molecular gas fraction. Variations in the H2 / HI ratio can result from changes in the efficiency of H2 ... Since the greatest HI depletion in the Virgo spirals occurs in the outer disks, well ...