Merging Y

NASA, ESA, the Hub­ble Her­itage (STScI/AURA)-ESA/Hubble Col­lab­o­ra­tion, and A. Evans (Uni­ver­sity of Vir­ginia, Charlottesville/NRAO/Stony Brook University)

Galaxy inter­ac­tions are always impres­sive. ESO 593–8 looks like the let­ter “Y,” swoop­ing eagle or a feather. Explore the NASA Hub­ble Space Tele­scope image of these merg­ing galax­ies. Do you see any pat­terns? What sto­ries can you tell?

The two spi­ral galax­ies will prob­a­bly merge to form a sin­gle galaxy in the future. Look for dark lanes of dust and bright blue star clus­ters at the outer fringes of the galax­ies. When galax­ies inter­act, gas and dust are pushed together. The gas and dust can col­lapse under its own grav­ity and new stars are formed. How­ever, exist­ing stars them­selves are not really dis­rupted by the merger. After sev­eral mil­lion years, the black holes at the cen­ter of these galax­ies will merge and the stars will set­tle into new orbits around a new galac­tic cenÂter.

A num­ber of faint back­ground galax­ies can be found through­out the image. The bright stars are fore­ground stars in our own Milky Way Galaxy.

ESO 593–8 lies about 650 mil­lion light-years from Earth toward the con­stel­la­tion Sagit­tar­ius, the Archer. A light-year is the dis­tance light trav­els in a year; about 6 tril­lion miles. When light left this galaxy pair, many geol­o­gists believe Earth’s sur­face was almost entirely cov­ered by ice in what’s known as Snow­ball Earth or Mari­noan Glacia­tion. But the planet was on the verge of a sud­den explo­sion in the diver­sity in life. Dur­ing the later Pro­tero­zoic, bac­te­ria and green algae were com­mon in the seas of Earth. Soft-bodied worms swam in these seas. Ani­mals had not yet ven­tured onto land.