The hr diagram is an important astronomical tool for understanding how stars evolve over time. The most luminous stars would be those that are large and hot. Interpreting the hr diagram of stellar clusters stars are created deep within giant molecular clouds. It turns out that the difference is the age of the stars. The hr diagram was created by ejnar hertzsprung and henry norris russell. Each student gets 36 stars, depending on class size, collects some data about their stars and then adds their data points to the graph on the board. Jul 23, 2015 the hr diagram plots stars luminosity versus temperature, and most stars fall along the main sequence, where they live most of their lives. It doesnt have any very massive stars on the upper left end of the main sequence. From this diagram you can determine star properties as well as its life stage. From the location of a star on the diagram, its luminosity, spectral type, color, temperature, mass, age, chemical composition and evolutionary history are known. By comparing the radii of different stars you will then find out. The secondmost concentration of stars is along a horizontal branch. Pass out the client letter 1, data set 1, and hr diagram sheets to each group.
Click the picture for interactive version with questions. There are some questions to answer about the stars. The hr diagram is a graphical tool that astronomers use to classify stars according to their luminosity, spectral type, colour, temperature and evolutionary stage. Then you are going to use a relationship called stephans law to calculate the stars radii. Students need to be wellprepared to tackle this project. Hot stars inhabit the left hand side of the diagram, cool stars the right hand side. If youre behind a web filter, please make sure that the domains. This works best for a cluster, where you know the stars are all at the same distance. One important technique in science is to try and sort or classify things into groups and seek out trends or patterns. In this activity, we are going to be making a human hr diagram. The most famous diagram in astronomy is the hertzsprungrussell diagram.
Students may research different facts about each star phase and write what they find on the provided blank lines. Pulsating variable stars and the hertzsprungrussell diagram. Ask students to say which stars among the sample stars theyve been. Project 3hr diagram activity project 3hr diagram activity. An interactive and engaging solution to the hertzsprung. The graph is a hertzsprungrussell diagram, where a star s luminosity is plotted against its temperature. The hertzsprungrussell diagram of stellar types was named in part for him.
Plotting variable stars on the hr diagram activity. But in terms of the hr diagram, main sequence also refers to a roughly diagonal, slightly scurved line stretching between the upperleft and lowerright corners on which main sequence stars chart. Determining the sizes of stars using the hr diagram. This family portrait is an hr diagram with five stars on it and a background of the color each star would look through the filter of a spectrophotometer. In this project, you will make your own hertzsprungrussell diagrams. These stars are fusing helium into carbon or heavier elements in the core and hydrogen into helium in a shell surrounding the core. Astronomers use computer models to create a theoretical hr diagram for a population of stars with a specific age, say 500 million years. Luminosity is a measure of how much energy leaves a star in a certain period of time. The emphasis of this activity is the plotting of four types of intrinsic pulsating variable stars cepheids, rr lyraes, miras and semiregulars. By studying hr diagrams, later astronomers figured out the life cycles of stars.
Hr diagram student activity is an example of how evidence is used to construct a model to explain complex concepts in this case the evolution of stars which is fundamental to understanding the origin and evolution of the universe. The main sequence phase of a stars life cycle is that time during which hydrogen fusion takes place in its core. Background information and hr diagram explorer can be found at. Stellar evolution can not be studied by observing individual stars. List the color of the stars from hottest to coldest.
Explore the lifecycle of stars with star in a box activity. Students can come away thinking that an hr diagram is like a map, and what the track plots is the star s motion through space, not its. Whether it was a massive star some 5 or more times the mass of our sun or whether it was a low or. Included in the discussion are the sizes, energetics, temperatures, masses, and chemical compositions of stars. Since brighter stars have lower magnitudes, if you choose to plot magnitude on the yaxis, the values will decrease as you go up. Star sizes for this smaller hr diagram are found at the bottom of page 5. Thankfully, i downloaded their wonderful hr diagram lesson 5 years ago.
You will have a labeled chart and a series of points to plot. Pulsating variable star and hr diagram activity summary. May 07, 2015 the main sequence along the hr diagram is not a singular evolutionary path, as many had thought, but a portrait of the sky at one moment in time of stars with varying masses. Students plot and label the stars on a blank hr diagram and answer analysis questions using their hr diagram. From these points, you can deduce a lot of information about stars. With the application of theory, the hr diagram tells us how stars age and how one kind transforms itself into another. On this diagram, 95 percent of stars including the sun fall into a band that slopes diagonally from hot, bright, blue stars like regulus, to cool, dim, red stars. A diagram that used only the stars in a given volume of space such as the nearest stars would show most of the stars at lower right, because small, dim red stars are the most common. In the hertzsprungrussell hr diagram, each star is represented by a dot. List all the types color and size of stars that are found in the main sequence. Almost all stars fall along this line, and its known as. The hr diagram changes also so the hr diagram can also be thought. Jul 28, 2015 students create their own hertzsprungrussell diagram using a chart of 20 stars.
On the diagram, the xaxis represents temperature and the yaxis represents the brightness. This article describes the properties and evolution of individual stars. The diagram became known as the hertzsprungrussell or hr diagram. The hertzsprungrussell diagram can also be used to measure the distance of star clusters from the earth. In this model eliciting activity mea, students will categorize a list of stars based on. What happens next in the life of a star depends on its initial mass. Start studying astro exam 3 nearest stars, brightest stars, and hr diagram. The graph is a hertzsprungrussell diagram, where a stars luminosity is plotted against its temperature. The animation to the right lets you control the luminosity of the sample star. In the diagram, the main sequence is where all of the stars including the sun, are ordered from cold to hot and from dim to bright. Based on the position of a star on the hr diagram, we can find out its luminosity, color, and spectral class. The star expands to larger than it ever was during its lifetime a few to about a hundred times bigger.
The information panels allow you to compare the sun with your star. Plot the luminosity on the yaxis with brighter stars going toward the top. The smallest stars are red and dont give off much of a glow. Study 1,896 terms space science flashcards quizlet.
The main sequence phase of a star s life cycle is that time during which hydrogen fusion takes place in its core. Ejnar hertzsprung, danish astronomer who classified types of stars by relating their colour to their absolute brightnessan accomplishment of fundamental importance to modern astronomy. An explanation of the hertzsprungrussell diagram in. How is it possible for white dwarf stars to have lower luminosity than the sun even though the sun is cooler than white dwarfs.
The hr diagram project is complex and involves many different skills. I project and take notes on my page by rewriting student thinking. The most luminous stars are affected not only by temperature but also by size. Using the graph below, plot the stars from group 1. Comparison diagram of human lifetime and star lifetime stars and humans share a similar phases in.
The hr diagram is going to help us learn something about how stars change as they get older. Developed independently in the early 1900s by ejnar hertzsprung and henry norris russell, it plots the temperature of stars against their luminosity the theoretical hr diagram, or the colour of stars or spectral type against their absolute magnitude the observational hr diagram, also known. Since we cant go to stars, all we can know about them is what we can see from earth. The upper left corner of an hr diagram includes the hot, bright, blue stars. In fact, it seems that stars are usually born in big groups, as members of a cluster of stars. The first presents a modern classical hr diagram and its description. On the other hand, a diagram that showed only the brightest stars would fill out mainly the upper part of the chart. The color of a star is determined by its surface temperature, which is illustrated on the hertzsprungrussell diagram. Star, any massive selfluminous celestial body of gas that shines by radiation derived from its internal energy sources.
The traditional hertzsprungrussell hr diagram activity is a plot of the nearest and brightest stars. An hr diagram for the nearest stars sdss skyserver dr14. At the end, you can pass out the student sheets to the students or have them work in. Stellar evolutionary tracks in the hr diagram astronomy 801. The majority of stars belong to the main sequence group. The hertzsprungrussell diagram is a graph that plots the temperature of a star against its absolute magnitude or luminosity. Stellar evolution can not be studied by observing individual stars as most changes occur over millions and billions of years.
Star, hr diagram, stellar, luminosity, brightness, properties. Human hr diagram activity teacher guide ut astronomy. The life of a star if youre seeing this message, it means were having trouble loading external resources on our website. Objects that fall below the main sequence are generally very compact objects that do not do fusion in their core, such as white dwarfs not to be confused with small main sequence stars, also called dwarfs. Most stars are classified by surface temperature spectral. The hertzsprungrussell diagram hertzsprungrussell diagram. In a true hr diagram, you would plot the effective temperature of a star on the xaxis and the luminosity of a star on the yaxis. For stars, this is the hertzsprung russell diagram. If you look at an image of a hertzsprungrussell diagram, you can see theres a diagonal line from the upper left to the lower right. Thus the location of a star on the hr diagram can tell you something about what is going on inside, and where the star is in its lifetime. The natures of nearly all the myriad kinds of stars are beautifully expressed within its confines.
However, it is very dim and therefore off the main sequence. You are about to create your own hr diagram, a chart that revolutionized the study of stars. Learn vocabulary, terms, and more with flashcards, games, and other study tools. The classical hr diagram, first constructed in 1914 by henry norris russell to which was added the work of ejnar hertzsprung, is a plot of absolute visual magnitude against spectral class. They classified the stars by their temperature against their luminosity. Project 3 hr diagram activity after plotting both the brightest stars and the nearest stars within the same hr diagram, we can determine which of these groups the brightest stars or the nearest stars represents each of the star groups super giants, giants, main sequence stars, and white dwarfs. Any highmass stars born in the globular cluster have already left the main sequence. Once you have plotted the stars from group 2, answer group 2 questions. It compares the relative radius, surface temperature, brightness luminosity and mass of the star to the sun. Many scientific discoveries are made first theoretically and then proven to be correct, or nearly so, in the laboratory. There is a peeling off from the main sequence of stars moving to populate the upper right region of the hr diagram, where the red giants live. Buck lodge middle school adelphi, md this booklet, along with its matching poster, is meant.
Next, we move on to analyzing the hr diagram further. Students discuss where the stars belonged on the diagram and how the. This process occurs in older stars and causes them to swell up, making them brighter, but also cooler and redder at the surface. They use this information to diagram the different colors of stars according to their brightness, temperatures, and color using the hertzsprungrussell diagram and a series of questions to summarize their understanding. Some of the stars from this activity are already labeled on the hr diagram and some are not. A description of how the hr diagram describes the properties of stars. From the list of 90 stars, choose at least 40, divided as follows. Draw arrows on the hr diagram showing the various stages the sun will go through until the end of its life cycle.
Those that are the least luminous would be small and cool. Then complete the following questions related to the background information. The blue and the white stars are the hottest, and the red, orange, and yellow stars are the coolest. Astrophysicists observe numerous stars at various stages in their evolutionary history to determine their changing properties and probable evolutionary tracks across the hr diagram. These variable stars can be thought of as representing transition stages for some stars as they evolve from the main sequence and move to other branches of the hr diagram. In this model eliciting activity mea, students will categorize a list of stars based. This diagram is a plot of luminosity absolute magnitude against the colour of the stars ranging from the hightemperature bluewhite stars on the left side of the diagram to the low temperature red stars on the right side. Studies have shown that this is a topic that can introduce and reinforce a misconception about stars. An interactive and engaging solution to the hertzsprungrussell. The results are plotted on a luminositytemperature hr diagram in time steps with representations of star size. Bright stars at the top, faint stars at the bottom. Apr 24, 2012 a description of how the hr diagram describes the properties of stars. The coolest stars are much fainter than the hot stars, and they lie at the lower right. Recall that a mainsequence star is what we usually think of as a normal star, meaning one that generates energy through hydrogen fusion in its core.
The hertzsprungrussell diagram hertzsprung and russell had the idea of plotting the luminosity of a star against its spectral type. Students will plot, label and interpret the hertzsprung russell diagram. Objective students will plot, label and interpret the. So you can already see that this is a very powerful diagram indeed. A star s life is long compared to that of a human, but we can see the stages of stellar birth, aging, and death in the heavens. This interactive applet might help you visualize some of the properties of the hr diagram.
The most difficult part of making an hr diagram is finding the luminosities of stars. The position of each dot on the diagram tells us two things about each star. When the absolute magnitude mv intrinsic brightness of stars is plotted against their surface temperature. A completed life cycle of stars booklet with answers. For the hr diagram project, students need to know that spectral types tell you the temperatures of. These have been constructed from stellar data bases and made into a format that can be read by ms excel. The spectral class gives the stars relative temperature, hence its horizontal location in the hr diagram. Hertzsprungrussell diagram students britannica kids. A significant tool to aid in the understanding of stellar evolution, the hr diagram was discovered independently by two astronomers. Once the students understand the instructions for the assignment step 6, allow.
Most of the stars on the hr diagram are classified as which type of star. Our sun is a fairly average star and sits near the middle. The diagram was created independently in around 1910 by ejnar hertzsprung and henry norris russell, and represented a major step towards an understanding of stellar. Describe the pattern made by the stars on your graph. The hr diagram plots stellar luminosity against surface. The hertzsprungrussell diagram is one of the most important tools in the study of stellar evolution. There are a few hundred billion stars in our galaxy, the milky way and billions of galaxies in the universe. This booklet is a fun hands on activity for students to use in their interactive notebooks. This hr diagram plots a sampling of the nearest stars and the brightest stars. Instead of plotting the individual points, they plot a line that goes through the points of all of the stars in the hr diagram. The graph they make is so large that they have to be up and moving around to put all of their stars on the hr diagram. Determining the sizes of stars using the hr diagram exercise in this exercise, you are going to use an hertzsprungrussell diagram to determine the luminosity and temperature of stars. A plot of the nearest stars on the hr diagram is shown below. When we look at such regions, we often see not just one, but a whole bunch of stars forming together.
Once you know the luminosity and temperature or color of a star, you can plot the star as a point on the hr diagram. This activity is an extension of the traditional plotting activity, and begins. What is the approximate surface temperature of the sun. Construct the graph as a class using the magnetized set of stars. Bright star list 314 stars brighter than apparent magnitude 3. It was created by astronomers ejnar hertzsprung and henry norris russell about 1910, and can be used to chart the life cycle or evolution of a star most stars, including the sun, can be found in the main sequence of stars a prominent band running from the topleft. The hertzsprungrussell diagram, abbreviated as hr diagram, hr diagram or hrd, is a scatter plot of stars showing the relationship between the stars absolute magnitudes or luminosities versus their stellar classifications or effective temperatures. That was not the case however, for the hertzsprungrussell diagram.
Pulsating variable stars and the hertzsprung russell diagram. When studying the evolutionary tracks of stars, we often talk about how stars move in the hr diagram. The band connecting the hot, bright stars at the upper left to the cool, faint stars at the lower right is called the main sequence. The hr diagram spans a rather large range in luminosity, from 104 l on the low end to as much as 10 6 l on the high end. Below is a version of the hertzsprungrussell diagram, which shows how the size, color, luminosity, spectral class, and absolute magnitude of stars relate. Stars that are in their main sequence normal stars are categorized by their color. Since this line indicates the positions of stars with a specific age, it is called an isochrone. The full spectral classification of a star tells us the approximate location of the star on the hr diagram. Stars and the hertzsprungrussell diagram teacher sheet. The more bright a star is, the higher temperature and the dimmer a star is, the colder temperature. A lot of background on star colors and spectral types can be found in skyservers color and spectral types projects. The hr diagram, as its known for short, plots a star s luminosity its true brightness against its surface temperature.
Of the 12 brightest stars in our sky, most are giants and supergiants. Supergiants are the same as giant stars, but they are much bigger and much brighter. Read and learn for free about the following article. Aug 22, 2015 the hertzsprungrussell diagram lessons. Once you have plotted the stars from group 1, answer the group 1 questions.
The next concentration of stars on the hr diagram is the horizontal giant branch. The luminosity class gives the stars relative luminosity at a given temperature, hence its vertical location in the hr diagram. There are lots of stars out there, so there are lots of dots. The star circles and the lesson i created from the materials kept students active and engaged for an entire block. How does the hr diagram explain the life cycle of a star.
535 598 566 1196 835 835 154 1340 1124 1275 1454 832 89 71 368 1115 1308 1318 1487 975 756 472 1348 363 467 279 766 1428 934 622 1023 921 1081 925 1406 984 112 809 1455