How does size temperature color and mass affect the life-cycle of stars?

Answer 1

The life cycle of a star is simply determined by what element said star is currently fusing. Our sun is currently burning through its vast supply of Hydrogen, and when that runs out it will switch to Helium, and so forth. Every time the mass of the element it's fusing increases, the energy given off by the fusion process also increases. This causes a star to swell, forming its red giant phase. Unfortunately any given star will eventually reach the point where the temperature and pressure within its core are not sufficient to fuse the element it's left with, and the star will die by either going supernova or shedding off it's gaseous outer layers and leaving behind a white dwarf.

Answer 2

No, the star colour is based on the elements which its made up from. They also use the light which comes off the stars to measure to distance of how far away it is and what the star is made up from i.e. Hydrogen = Yellow

Answer 3

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Vista Unit: UT) Earth and Space Science (Earth Materials/Constancy and Change) Grade 6 ... Things are Constantly ChangingLearning Experience:11 - Life Cycle of a StarAuthor(s): Julie Everett-Sahlin

School(s): Aldine ISD

Subject: Science

Grade level: 6

Time Frame: 2 hour(s)

Description:

Students will learn the life cycles of low mass, medium mass, and high mass stars.

Students will use the Hertzsprung-Russell diagram to trace the life cycle of a star.

Educational Objectives:

Vocabulary:

low mass star - small, cool star; has the longest life cycle

medium mass star - medium size star with medium temperature; uses up hydrogen faster than a low mass star

high mass star - hottest and most massive star; uses up hydrogen quickly; it will swell to become a supergiant and then explodes as a supernova

nebula - large, cool gas and dust cloud that is the birthplace of a star

protostar - when gravity acts on a nebula, causing it to come together and form a dense center

fusion - an energy-forming process in which nuclei of atoms are joined together creating heat and light; caused by tremdous heat and pressure

main sequence stars - 90% of stars fall in the main sequence on the Hertzsprung-Russell Diagram; H-R diagram is based on the absolute magnitude and temperature of stars

Red Giant - when a medium mass star begins to use the helium in its center and expands

Nova - a star that briefly flares up 1,000 times more intensely than normal

Supernova - a violent explosion that occurs after a high mass star quickly uses up all the material in the star for fuel; one of the most violent explosions in the universe

Supergiant - When a high mass star quickly uses up all the hydrogen in its core, it swells.

white dwarf - what low and medium mass stars become at the end of their life cycles

neutron star - one of the two things a high mass star can become after being a supernova; a small dense core

black hole - one of the two things a high mass star can become after being a supernova; the core can collapse and become so dense that light cannot escape because of gravity

Concept Strand:

Students will need to know that stars are large balls of gases that burn hydrogen to produce heat and light.

Materials:

sequence cards

glue

paper

scissors

pencils

crayons or map pencils

Hertzsprung-Russell Diagram

transparency of Hertzsprung-Russell Diagram

Analysis Page

Teacher Background:

Stars are large balls of hot, glowing gases. Stars produce this energy from the burning caused by the fusion of hydrogen. Fusion is when the nuclei of two atoms are joined together. The effect of the nuclei joining produces heat at high temperature and light. Large amounts of heat and pressure at the core of the star enables fusion to occur.

Stars can appear to have different colors. The colors can give us clues to the temperature of that star by looking at it. Temperatures of stars range from red being the coolest to blue being the hottest. Our sun is a yellow star, which falls between the red and blue.

Astronomers use a scale called the Hertzsprung-Russell Diagram to classify stars. This diagram looks at the temperature, color, and absolute magnitude of the stars. Ninety percent of all stars fall in the category called Main Sequence stars. In the Main Sequence Band, stars range from the hot, bright, blue stars in the upper left corner to the cool, dim stars in the lower right corner. The stars with the greatest mass are the hottest and the brightest. So a star with Spectral Class D and Absolute magnitude of -5 would be a star with great mass and high temperature; therefore, its life span would be short. At the other end, a star in Spectral Class M and Absolute Magnitude of +10 would be a low mass, cool star; therefore, it would have a long lifetime. Red Giants and Supergiants have a high Absolute magnitude and fall in the G-K spectral class, which causes them to not fall in the main sequence. Also, White Dwarfs have Absolute Magnitude of +15 to +5 and a spectral class of A-G, causing them not to be part of the Main Sequence.

The life cycle of a star begins as a cloud of gas and dust called a nebula. Compression waves traveling through this nebula create dense gas knots. Gravity then pulls more gas particles together. When these large gas centers form, a nebula becomes a protostar. When gravitational forces continue to raise the pressure and temperature (15 million degrees C) in the protostar, then fusion begins. In a main sequence star, hydrogen is burned. The death of a star begins after it runs out of hydrogen to burn. It will take a star millions to billions of years to reach this stage. All stars go through 3 main stages: nebula, protostar, and main sequence star.

Life Cycle of a Low Mass Star

A small, cool star uses up its hydrogen more slowly than the larger stars. It begins its life like all stars, as a nebula. Then it becomes a protostar and once fusion begins, it becomes a main sequence star. It can stay at this stage for billions of years. When it has used up all its hydrogen, it will shrink and become a white dwarf.

Life Cycle of a Medium Mass Star

A medium mass star, like our sun, burns its hydrogen more quickly than a low mass star. It, like the low mass star, starts life out as a nebula, then becomes a protostar. After fusion begins, it enters its time on the main sequence. A medium mass star will spend around 10 billion years as a main sequence star. When a medium mass star runs out of hydrogen, it will use the hydrogen in its outer layers for fuel. This causes the star to swell into a Red Giant. The burning of hydrogen in the outside layers causes the expansion while the core is actually shrinking. When it becomes a red giant, it will swell its diameter from 10 to 1,000 times its original size. Once all the hydrogen is used up in the star, the pressure in the shrinking core will cause the nuclear reactions between the helium nuclei in the star. At this point, the inner core stops contracting, and the outer layers begin to contract, eventually shrinking into a white dwarf. Sometimes when a larger medium mass star collapses, it will flare up brightly for a few weeks as it blows its outer layer of gas and dust into space. This is called a planetary nebula.

Life Cycle of a High Mass Star

A high mass star begins its life like the low and medium mass stars. Its starts as a nebula, then becomes a protostar, and then a main sequence star. Because a high mass star burns hydrogen quickly, its life span is millions of years instead of billions. After quickly exhausting its hydrogen supply, a high mass star quickly expands to become a Super Giant. A super giant can be 500 times the size of our sun. Because it is so large, the core continues to heat up and use other elements as its fuel. After heating to such a high temperature, the star then explodes into a supernova. A supernova is one of the most violent things to happen in the universe. Afterwards, the star will collapse into a neutron star or black hole. A black hole will occur when an extremely massive star collapes into a matter that is so dense that light cannot even escape. Astronomers believe that the elements released during the collapse of a supernova are the source of the elements for planets and life.

Advanced Preparation:

Make sure you have a diagram for each child.

Procedures:

1. Discuss with students the types of stars. Discuss the characteristics of each type.

2. Introduce the Hertzsprung-Russell Diagram to the students. Go over the terms Absolute Magnitude and Spectral Class. Show students how to read the diagram. Discuss the main sequence and why the white dwarfs, red giants and supergiants do not fit on the main sequence.

3. Discuss the life cycle of the three types of stars. Show diagrams of the 3 life cycles. Discuss each stage of the life cycles.

4. Have students assemble their own life cycle charts for each type of star.

5. Give students the page with the Spectral Class and Absolute Magnitude recorded. Have students individually locate these stars on the main sequence and write the life cycle of the star. Example: Spectral Class M Absolute magnitude +10 would be a low mass star; therefore, they should draw the life cycle of a low mass star.

Formative assessment:

Life Cycle Chart for all three star types

diagram analysis

Answer 4

There's an old saying; "The bigger they are, the harder they fall." It was originally meant to apply to bullies, but it works equally well with stars.

Small stars, only a little more massive than the minimum mass required to support fusion, may continue essentially forever; hundreds of billions or perhaps even trillions of years.

"Medium sized" stars, near the mass of our Sun, can continue for perhaps 10 billion years, with the smaller stars lasting longer and the bigger ones dying sooner. We expect that our Sun, already about 4.5 billion years old, probably has another 4 billion years of "life".

But the more massive the star is, the more quickly it ends. Supergiants like Betelgeuse are already approaching their deaths after only about 10 million years or so. Betelgeuse almost certainly has less than 1 million years remaining, and could explode as a supernova in the near future. Of course, "the near future" means "less than 100,000 years" to an astronomer, so don't go out this evening looking for the bright flash!

Answer 5

Poet Edna St. Vincent Millay wrote a poem in 1920 about this very subject. It reads:

My candle burns at both ends;

It will not last the night;

But ah, my foes, and oh, my friends-

It gives a lovely light!

OK, her poem wasn't really about the relationship between stellar mass and its lifespan. But it still works. The greater a star's initial mass, the faster and the hotter it will fuse, and the sooner it will run out of hydrogen fuel.

A star like our Sun has a total "life expectancy" of about 10 billion years. A really large star like the red giant Betelgeuse (in the shoulder of Orion) is already "old" at 100 million years or so.

Answer 6

It's mass.

See related question for more information.

Answer 7

Its mass and Size.

Answer 8

Mass