Astronomy: Stellar Evolution

Black Holes ______________ are compressed balls of _______ that cannot be compressed further. If the initial mass was _______ , then there would be _______ of a squeeze on these neutrons. If these neutrons collapse into even a smaller space smaller than a _______, they can form a _______! Scientists know of no force that can counteract _______ beyond the point of ______________ Once beyond a critical point of ______________ and _______ a ball of _______ would become a _______ . The _______ of a black hole is so strong, no _______ is capable of escaping from it not even _______ . Black Holes can be thought of as having infinite _______ in an infinitely small _______. In reality, black holes simply have an escape speed larger than the ______________ (300,000 km/s). This is caused tremendous gravity compressing mass into an incredibly small size. Because no radiation escapes from a black hole we can't detect any _______or _______with _______.We can only hope to detect the______________ of black holes. We can tell if something gets sucked in and disappears, or if light is bent or distorted near them.

Black Holes *Neutron stars* are compressed balls of *neutrons* that cannot be compressed further. If the initial mass was *greater*, then there would be *more* of a squeeze on these neutrons. If these neutrons collapse into even a smaller space smaller than a *pinhead*, they can form a *black hole*! Scientists know of no force that can counteract *gravity* beyond the point of *neutron degeneracy*. Once beyond a critical point of *compression* and *gravity* a ball of *neutrons* would become a *black hole*.The *gravity* of a black hole is so strong, no radiation is capable of escaping from it not even *light*. Black Holes can be thought of as having infinite *gravity* in an infinitely small *space*. In reality, black holes simply have an escape speed larger than the *speed of light* (300,000 km/s). This is caused tremendous gravity compressing mass into an incredibly small size. Because no radiation escapes from a black hole we can't detect any *waves* or *light* with *telescopes.* We can only hope to detect the *gravitational fields* of black holes. We can tell if something gets sucked in and disappears, or if light is bent or distorted near them.

Huge Super Giant becomes a ___________

Huge Super Giant becomes a *Black Hole*

The 7 Stages of Solar-Type Star Formation

Stage 1: An Interstellar Cloud Stage 2: A Collapsing Cloud Fragment Stage 3: Fragmentation Ceases Stage 4: A Protostar Stage 5: Protostellar Evolution Stage 6: A Newborn Star! Stage 7: The Main Sequence

Neutron Stars Neutron Stars are stars that originally had more ____ than _______ stars and therefore collapse more. Neutron stars are VERY _______. Neutron stars are very _______ and spin very _______ ! Neutron stars are what is left after _______ explosions occur.

Neutron Stars Neutron Stars are stars that originally had more *mass* than *white dwarf* stars and therefore collapse more. Neutron stars are VERY *SMALL*. Neutron stars are very *dense* and *spin* very fast! Neutron stars are what is left after *supernova* explosions occur.

Pulsars The first neutron star was detected in _______ by _______, a graduate student at Cambridge University. It was detected with a ______________ and was found to be giving off rapid pulses. This "pulsar" was a __________________ that was aligned just right to be "heard" on the Earth.

Pulsars The first neutron star was detected in *1967* by *Jocelyn Bell*, a graduate student at Cambridge University. It was detected with a *radio telescope* and was found to be giving off rapid pulses. This "pulsar" was a *spinning neutron star* that was aligned just right to be "heard" on the Earth.

Regular/Average Star Evolution

Regular/Average Star > Red Giant > White Dwarf

Regular/Average Star Evolution happens to ________

Regular/Average Star Evolution happens to *Type G Stars like our Sun*

Stage 1: An Interstellar Cloud These are large, cold __ K clouds that span ___ of ____ across. Once _______(+) over takes _______(-), the cloud loses _______. To regain _______, the cloud breaks into _______, more manageable portions.

Stage 1: An Interstellar Cloud These are large, cold *10* K clouds that span tens of parsecs across. Once *gravity* (+) over takes *heat* (-), the cloud loses *equilibrium*. To regain *equilibrium*, the cloud breaks into *smaller*, more manageable portions.

Stage 2: A Collapsing Cloud Fragment We will now focus on just one of the smaller _______of the original. The cloud at this stage is still _______ the size of our solar system. Remember, particles give off _______. The _______given off from the particles in the _______ cause the middle of the cloud to _______ up

Stage 2: A Collapsing Cloud Fragment We will now focus on just one of the smaller *fragments* of the original. The cloud at this stage is still *100X* the size of our solar system. Remember, particles give off *radiation*. The *radiation* given off from the particles in the *center* cause the middle of the cloud to *heat* up

Stage 3: Fragmentation Ceases After tens of thousands of years, the _______ (of the cloud) is now the size of ______________ . This is still 10,000 X the size of our _______.The central temperature is now getting _______

Stage 3: Fragmentation Ceases After tens of thousands of years, the *fragment* (of the cloud) is now the size of *our solar system*. This is still 10,000 X the size of our *Sun*. The central temperature is now getting *very hot*.

Stage 4: A Protostar Protostar - A stage in stellar evolution when the _______ of a _______ fragment of _______ is sufficiently _______ and _______ that it becomes _______ to its own radiation. At this stage the star starts to "_______ ". The protostar is the _______ region at the _______ of a fragment. _______ never made it this far it did undergo stages 1-3.

Stage 4: A Protostar Protostar - A stage in stellar evolution when the *interior* of a collapsing *fragment* of *gas* is sufficiently *hot* and *dense* that it becomes opaque to its own radiation. At this stage the star starts to "*shine*". The protostar is the dense region at the *center* of a fragment. *Jupiter* never made it this far, it did undergo stages 1-3.

Stage 5: Protostellar Evolution The protostar is now only about ___ the size of our Sun. Surface Temperature = _______ K Internal Temperature = _______ K The core is still too _______ for_______ n to occur. As material continues to _______, internal (core) temperatures ___

Stage 5: Protostellar Evolution The protostar is now only about *10X* the size of our Sun. Surface Temperature = *4000* K Internal Temperature = *5,000,000* K The core is still too *cool* for *nuclear fusion* to occur. As material continues to *contract*, internal (core) temperatures *rise*

Stage 6: A Newborn Star! After _______ years, the protostar is _______ and _______ enough to initiate ______________ and a star is _______ ! At first, the star is _______ , but not as _______ as our Sun. Over time, the star _______ and temperatures _______ .

Stage 6: A Newborn Star! After *10 million* years, the protostar is *dense* and *hot* enough to initiate *nuclear fusion* and a star is born! At first, the star is *larger*, but not as *hot* as our Sun. Over time, the star *contracts* and temperatures *increase*.

Stage 7: The Main Sequence Over the next _______ years, the star travels along the _______ sequence until _______ is reached. Stage 1 - 7 takes about _______ years. Then it remains _______ (in balance) for the next _______ years. What happens to a star when it "dies" depends on its original _______

Stage 7: The Main Sequence Over the next *30 million* years, the star travels along the *main* sequence until *equilibrium* is reached. Stage 1 - 7 takes about *40 - 50 million *years. Then it remains *unchanged* (in balance) for the next *10 billion* years. What happens to a star when it "dies" depends on its original *mass*

Stars Forming: Our universe is constantly _______ itself by _______ and _______ stars. Billions of stars have been born, lived out their lives, and died since our Galaxy formed. _______ gas and _______ clouds left over from old stars condense to form new stars. _______and _______ are vital factors that will determine if an interstellar gas will become a _______. Atoms are attracted to one another and will _______. (+). _______makes atoms and molecules move_______ faster and so they _______. (-) Conditions must be just right for stars to form. (+/-)

Stars Forming: Our universe is constantly *renewing* itself by *creating* and *destroying* stars. Billions of stars have been born, lived out their lives, and died since our Galaxy formed. *Interstellar* gas and *dust* clouds left over from old stars condense to form new stars. *Gravity* and *heat* are vital factors that will determine if an interstellar gas will become a *star*. Atoms are attracted to one another and will condense. (+). Heat makes atoms and molecules move faster and so they spread out. (-) Conditions must be just right for stars to form. (+/-)

Super Giant becomes a ___________

Super Giant becomes a *Neutron Star*

White Dwarf A white dwarf is a star that has a very ___ temperature that glows ____. _______ is a white dwarf. These are very ____ stars though _____ stars are smaller.

White Dwarf A white dwarf is a star that has a very *hot* temperature that glows *white*. *Sirius B* is a white dwarf. These are very *small* stars though *neutron* stars are smaller.