Why do many galaxies appear as spirals [
http://antwrp.gsfc.…]? A striking example is M101, shown above [
http://www.astr.ua.…], whose relatively close distance of about 22 million light years allow it to be studied in some detail. Recent evidence [
http://adsabs.harva…] indicates that a close gravitational interaction with a neighboring galaxy created waves of high mass [
http://lsnt7.lights…] and condensed gas which continue to circle the galaxy [
ftp://crux.astr.ua.…]. These waves compress existing gas and cause star formation [
http://antwrp.gsfc.…]. One result is that M101 [
http://antwrp.gsfc.…], also called the Pinwheel Galaxy, has several extremely bright star-forming regions (called HII regions) spread across its spiral arms. M101 [
http://www.seds.org…] is so large that its immense gravity distorts smaller nearby galaxies.
Explanation
Why do many galaxies appear as spirals [
http://antwrp.gsfc.…]? A striking example is M101, shown above [
http://www.astr.ua.…], whose relatively close distance of about 22 million light years allow it to be studied in some detail. Recent evidence [
http://adsabs.harva…] indicates that a close gravitational interaction with a neighboring galaxy created waves of high mass [
http://lsnt7.lights…] and condensed gas which continue to circle the galaxy [
ftp://crux.astr.ua.…]. These waves compress existing gas and cause star formation [
http://antwrp.gsfc.…]. One result is that M101 [
http://antwrp.gsfc.…], also called the Pinwheel Galaxy, has several extremely bright star-forming regions (called HII regions) spread across its spiral arms. M101 [
http://www.seds.org…] is so large that its immense gravity distorts smaller nearby galaxies.
Explanation
