Why do stars typically form in clusters rather than in isolation?

Stars copy each other — once one star forms, nearby gas automatically forms more stars Giant molecular clouds are much more massive than a single star, so when they collapse they fragment and form many stars at once Stars need other stars nearby for gravitational support when they first form Magnetic fields in space force gas particles to clump together in large groups

What is an open star cluster?

An old, dense sphere of millions of stars found in the galaxy's halo A cloud of gas that has not yet finished forming stars A young, loosely gravitationally bound group of hundreds to thousands of stars that formed from the same molecular cloud A cluster that is moving away from the galaxy at high speed

What are the Pleiades?

An ancient globular cluster containing millions of old stars A famous open star cluster about 440 light-years away, roughly 100 million years old, also called the Seven Sisters The nearest star-forming region to Earth, only 10 light-years away A group of seven stars that orbit each other as a tight gravitational system

Why do open clusters eventually disperse over time?

They all explode as supernovae once their stars run out of fuel The stars in open clusters stop moving and spread out on their own Gravitational interactions with passing molecular clouds and other stars gradually pull the cluster's stars apart Open clusters are absorbed whole by black holes at the galaxy's center

What is a globular cluster?

A young cluster of hundreds of stars in the spiral arms of a galaxy A tightly packed, spherical cluster of 100,000 to millions of very old stars found in the halo of a galaxy A cluster of stars that orbit each other in perfect circles A cluster of galaxies held together by gravity

Why do stars in globular clusters contain very few heavy elements?

Heavy elements sink to the center of globular clusters and are hidden from view Globular clusters formed 10-13 billion years ago when the universe had very little heavy elements — they had not yet been forged and spread by enough supernovae Heavy elements evaporate from stars in globular clusters because they are so densely packed Globular clusters form from pure hydrogen gas clouds that never mixed with supernova material

What is Omega Centauri?

A supernova remnant in the constellation Centaurus A planetary nebula discovered by the Hubble Space Telescope The largest globular cluster in the Milky Way, containing about 10 million stars The nearest open star cluster to our solar system

Why are globular clusters considered important fossils of galaxy formation?

They contain the oldest known black holes in the universe They orbit outside the Milky Way, making them easier to study Their very old stars formed in the early universe, preserving a record of the chemical composition and conditions of that time They have not changed at all since the Big Bang, unlike open clusters

How does the age of a typical open cluster compare to that of a typical globular cluster?

Both types are typically about 5 billion years old, the same as our Sun Open clusters are older because they have had more time to spread out Open clusters are typically less than 1 billion years old; globular clusters are typically 10-13 billion years old Globular clusters are younger because they are more tightly packed and protected

Where are globular clusters located relative to the Milky Way's disk?

Inside the galactic disk, mixed in with open clusters Only in the very center of the galaxy, near the black hole In the galaxy's halo — a large spherical region extending above and below the disk In the spiral arms, where star formation is most active