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Astronomy 7th Grade Chapter 2.2 The Beginning and End of Stars A star enters the first stage of its life cycle as a ball of gas and dust. As this ball of gas becomes denser, it gets hotter and changes to helium – __________________. As stars age, they lose some of their material. When a star dies, they could explode in the form of a ____________________. DIFFERENT TYPES OF STARS Stars can be classified by their: Size Mass Brightness Color Temperature Spectrum Age PROTOSTAR: A Star is Born Born in a Nebula: an _____________and other _______________. A Baby Star ________ in Color Forms over _______ of years MAIN SEQUENCE Second and ____________ stage of a star’s life cycle Energy is generated in the core of the star. Hydrogen atoms fuse into Helium atoms. This process releases an ENORMOUS amount of Energy. GIANTS and SUPERGIANTS Third Stage of Life Cycle RED GIANT: a star that _________ and ___________once it uses all of its hydrogen. The loss of hydrogen causes the center of the star to _________________. The atmosphere of the star grows very _______ and _______________ to form this RED GIANT! Red Giants: 10x bigger than the Sun. Super Giants: 100 x bigger than the Sun WHITE DWARFS FINAL stage of a star’s life cycle. Has same mass as the sun or smaller White Dwarf: small, hot star that is the leftover center of an older star NO _______________ LEFT! NO LONGER CAN GENERATE __________ by fusing hydrogen atoms into _____ atoms. Can shine for _____________of years even after they die. SUPERNOVAS Supernova: A gigantic ____________ in which a massive star collapses and throws its outer layers into space. This explosion powerful that it could be brighter than an entire galaxy for days! NEUTRON STARS After a Supernova, the center of the collapsed star contracts to form a new star. The mass of the new star is about 2x the mass of the Sun – WOW! A star has collapsed under gravity to the point where all the star particles are NEUTRONS. PULSARS If a neutron star is ____________, it is called a PULSAR. A PULSAR sends out a beam of __________. The beam is detected on Earth by telescopes as rapid clicks, or pulses (hence – PULSAR). BLACK HOLES If the center of a collapsed star has a mass more than 3x the mass of the sun, the star may contract. The 3x star contracts because of the strength of its gravity. The force of the contraction CRUSHES the dense center of the star. It leaves a BLACK HOLE. BLACK HOLE: An object that is so massive that light cannot escape its gravity. WOOH!