`
Hertzsprung-Russell Diagram, a 2D diagram designed to plot temperature against luminosity and colour against absolute magnitude. Find out how this magnificent figure was invented during the early 20th century. – Ryota Kusumoto
The Hertzsprung-Russell Diagram (also known as the HR Diagram) is one of the most important tools in the study of stellar evolution. It was developed individually by 2 scientists, Ejnar Hertzsprung and Henry Norris Russel. The diagram made in the 1900’s, it plots the temperature of stars against luminosity or the colour of stars against absolute magnitude. To read the HR diagram there are several parts that need to be understood. In the middle stretching from the upper left to the bottom right is the Main Sequence stars where most normal stars including our sun occur. They range from hot and luminous (Upper left) to cool and faint (Lower right). These stars spend 90% of their lives burning hydrogen and helium in their cores. At the top right are the brightest stars called Supergiants and going down are the Red Giant. These stars have
…show more content…
low surface temperature but are very bright. Finally there are the white dwarfs which are located in the bottom left. These stars are the final evolutionary stage of low to intermediate stars and are very hot but low luminosities due to their small size. The 2 Stages The creation of this marvellous diagram began with 2 stages.
The first design originated in 1911 with Danish astronomer, Ejnar Hertzsprung plotted the absolute magnitude of stars against their colour. The second design originated in 1913 when American Astronomer Henry Norris Russel plotted spectral class against absolute magnitude. Their results showed a relationship between the temperature and luminosity and showed that they were not random but in fact fell in distinct groups. Depending on its starting mass, every star goes through the evolutionary stages dictated by its internal structure and how it produces energy. Each of the stages correspond to a change in temperature or luminosity which then changes the position of the star located on the HR diagram. Therefore astronomers can now know a star’s internal structure and which stage it’s at by locating the position of where the star lies on the
diagram. Temperature of a Star Finding the temperature of a star through a telescope determines on the colour of the star. Astronomy has loads of references to colour such as the red giants and the white dwarfs. Stellar colours range from the deepest blues (the hottest about 28000 – 50000 K) to the brightest reds (the coolest 2000 – 3500K). The primary function of the colours on stars is to determine the effective temperature. The effective temperature refers to when the temperature of an object is calculated by the radiation it emits assuming the object is a black-body behaviour. A star works similarly to the black-body behaviour where the body when heated first off flows to a dull red, then orange, then yellow, white and eventually blue. If it was to become so hot then it would pass the blue and into the ultra violet region. These colours we observe are combinations of emissions from each wavelength. The reasons why blue appear to be the hottest stars is because most of the energy is emitted towards the blue side of the spectrum. Whereas when a star is cool, there is little to no emission on the blue parts and therefore appears to be red. Although our sun feels hot, compared to some other stars it is only ranked amongst the G-class (4900-6000 K). Mass-Luminosity Relation Not all main sequence stars are the same to the sun, some can be smaller and cooler while some can be bigger and hotter. Higher mass stars have shorter lifespans because they burn through their nuclear fuel faster and therefore have less hydrogen fuel to burn. An example could be given that if a star is 10 times the solar mass (the sun’s mass) it would be expected to live around 10 million years compared to the suns 10 billion. Through thousands of observations with the main sequence stars, a relationship was shown through the form of “L oc M3.5” or Luminosity of star B/Luminosity of star A = [Mass of star B/Mass of star A]3.5 where luminosity is measured in W and mass in kg. Because the mass is raised to a power greater then 1, the slightest difference can cause a star’s luminosity to differ greatly. For a star to be stable, it requires the star to be in hydrostatic equilibrium where the pressure of gravitational attraction to inner shells is equalled to the thermal and radiation pressure acting outwards. High mass stable stars have greater gravitational compression so the core temperature becomes higher. Higher core temperatures make the fusion between nuclei in the core which gives a greater rate of nuclear reaction and emission. This is why we have most high mass stars have corresponding high luminosities but die out far quicker then smaller stars. Stellar Evolution – Main Sequence Stars & White Dwarfs Stellar evolution is when stars change over time. To the human eye, the stars barely change over time but if a star is observed for billions of years, we would see the transformation of the star from day 1 to until it dies. Stars are born out of gravitational attraction of hydrogen nuclei called protostars. When the protostar has sufficient mass, the temperature becomes high enough for nuclear fusion to occur. All stars collapse when most of the hydrogen nuclei have fused into helium. Gravity now weighs heavier than the radiation pressure which makes the star shrink in size and heats up. The hydrogen in the layer surrounding the core is able to fuse therefore raises the temperature of the outer layer and makes them expand, forming a giant star. The fusion between the hydrogen adds more helium to the core which continually shrink and heat up. This in return creates heavier elements such as oxygen and carbon. Huge, massive stars will continue to fuse until nickel and iron are formed. From here depends on the mass of the star. Stars like the sun with small to moderate mass (Max of 4 solar mases) the core temperature will not suffice the fusion for carbon. This means that when the helium is used up, the core will shrink whilst emitting radiation. This takes away the outer layer of the star and forms a planetary nebula. When the core has shrunk to roughly the size of earth, it consists of oxygen and carbon ions surrounded by electrons. It then stops shrinking because of a principle called Pauli’s exclusion principle which prevents two electrons from being in the same quantum state. The electrons then provide a repulsive force that stops the star from collapsing in on itself by gravity. The star is then left to cool over billions of years which is then known as a white dwarf. Stellar Evolution – Super Nova’s & Black Holes The other path a star can take is when it is heavy and big. When a star’s mass and core is so large (Stars that belong in the red giants), it leads to high temperatures which cause the fusion of nuclei to create heavier elements than carbon. Once the giant phase ends, the dense core causes gravitational contraction. The Chandrasekhar limit tells us that it is impossible for a white dwarf to have a mass of more than 1.4 times the mass of the sun. With massive stars, the pressure cannot be stabilized so as the mass of the core reaches this value, the electrons combine with protons to form neutrons, emitting neutrinos in the process. The star eventually collapses with the neutrons come close to each other in the nucleus. The outer layers head towards the core but instead are bounced off causing a massive explosion – a supernova. This blows everything and leaves the core known as a neutron star. The neutrons provide a neutron degeneracy pressure that resists further gravitational collapse. But when the Oppenhimer-Volkoff Limit (Also known as the TOV limit, is an upper bound to the mass of stars composed of neutron-degenerate matter) allows the neutron star to further collapse, it ends up as a black hole. The values is estimates around 1.5 to 3 solar masses. It is impossible to form a neutron star by having a mass greater than the TOV limit but instead the remains of a supernova forms a black hole. Black holes are known for their ability to not let anything escape from a black hole, including the fastest known particles such as photons. For this reason it’s not possible to observe black holes directly but through the uses of x-rays, giant jets of matter and strong gravity fields the existence can be proven. Stellar Spectras
In document C, Ptolemy had a theory where the Earth was the center of the Solar System. Other scientists also had this theory when they were examining the stars and Earth's rotation. But other scientists figured out that the Sun was the center of the Solar System instead of Earth. Document D shows the zodiacs and how the stars lining up. These documents show how advance the people in the Renaissance were. Ptolemy and Copernicus were very advanced as well when they had their theories on the Solar System. Also when they would use the stars and constellations for the zodiac symbolizations (Doc
Many of the heavenly bodies were considered to be the representations of deities. The master of reason, Aristotle, stated once long ago that everything was made of only five elements the final being what makes up the heavenly bodies, after all they lacked the proper technologies to know differently. It was Galileo in 1610, using his telescope, that found dark spots on the sun. So as technological innovations occur our understanding of physics and astronomy grow. Newton in 1687 discovered the laws of gravity, suggested that all the solar and stellar bodies operated the same.
The two astronomers found many patterns after developing their graph. They found that 90% of stars graphed fell within a band that ran through the middle of the graph. These stars range from cool, dim, red stars at the lower right of the H-R Diagram to hot, bright, blue stars at the upper left corner of the H-R Diagram. The stars that fall into to this band are known as main-sequence stars. Stars such as the sun, and almost every start visible in the night sky fall within this band of main sequence stars. There is another group of stars which are cool and bright that appear near the upper right corner of the H-R Diagram.
It’s a white giant and has a temperature of 7700 Kelvin. It’s a type A star that is 8.5 times brighter than the sun. It is most likely to be in the last stage of ordinary star-type life. Scientists are saying the sun’s older twin is found in the middle of Capricorn. Studying this star will help them see how the Earth’s sun will develop.
In 1951, Solomon Asch carried out several experiments on conformity. The aim of these studies was to investigate conformity in a group environment situation. The purpose of these experiments was to see if an individual would be swayed by public pressure to go along with the incorrect answer. Asch believed that conformity reflects on relatively rational process in which people are pressured to change their behaviour. Asch designed experiments to measure the pressure of a group situation upon an individual judgment. Asch wanted to prove that conformity can really play a big role in disbelieving our own senses.
The first star, Mintaka, is a white-blue Supergiant. Its distance is said to be eight hundred light years from Earth. It is the farthest West in Orion’s Belt when looking from Earth. This star is ten thousand times brighter than our sun. Its surface temperature is a soaring sixty thousand degrees Celsius. Its mass is twenty times greater than our sun’s.
In 1594, Kepler left Tuebingen for the University of Graz to become a professor of astronomy. It was here that Kepler realized that figures of the type shown here determine a definite fixed ratio between the sizes of the two circles, provided the triangle has all sides equal, and a different ratio of sizes will occur for a square between the two circles, another for a regular pen...
If the nebula is dense enough, certain regions of it will begin to gravitationally collapse after being disturbed. As it collapses the particles begin to move more rapidly, which on a molecular level is actually heat, and photons are emitted that drive off the remaining dust and gas. Once the cloud has collapsed enough to cause the core temperature to reach ten-million degrees Celsius, nuclear fusion starts in its core and this ball of gas and dust is now a star. It begins its life as a main sequence star and little does it know its entire life has already been predetermined.
“New technology is not good or evil in and of itself. It’s all about how people choose to use it.” David Wong’s quote is saying we need.It could helps us but it also could harm us. The science fictional short story, “The Veldt written by Ray Bradbury relates to this quote extremely well. George lives in a Happylife Home with his wife Lydia and their two kids Wendy and Peter. After living in the Happylife for a while George and Lydia start to notice that their house is affecting their children. Wendy and Peter have a special room called the nursery. The kids go into to the room to experience things in 4D. You could choose settings and everything to make your experience the best for you. It was suppose to help them learn more efficiently but
Did you know that the sun’s core can reach about 15 million degrees Celsius? This bright star has many significant happenings. These interesting occurrences include sunspots, solar winds, coronal mass ejections, and solar flares. Sunspots are cool, dark-colored regions of the photosphere related to a shifting magnetic field inside the sun. However, sunspots are only dark in our perspective. A sunspot removed from the bright background of the Sun would glow brightly. Solar wind is the radiation of heat and a steady stream of charged particles. The wind blows about 450 kilometers a second throughout the solar system. Also, the Aurora Borealis occurs when highly charged particles from the sun's atmosphere move into the Earth's atmosphere via solar wind. Occasionally, particles will burst from the sun in a solar flare, which can disrupt satellite communications and knock out power on Earth. The flares are as powerful as millions of 100-megaton hydrogen bombs exploding at the same time! Coronal mass ejections are huge bubbles of gas braided with magnetic field lines that are ejected from the Sun over the course of several hours. Coronal mass ejections are known to be formed by explosive reconfigurations of solar magnetic fields through the process of magnetic reconnection, however its exact formation mechanism is not yet understood.
This star is a blue supergiant like Rigel, but even hotter. This high temperature means that more of its energy is radiated as ultraviolet and so it appears fainter than Rigel to our eyes. The fourth of the stars forming Orion’s rectangle is Bellatrix. This is again a hot blue star that at a distance of 240 light year is closer to us than most of the other stars in Orion.
A third explanation is that the distribution of stars is such that some hind behind others and so the lig...
However, this is where the questions start to enter. How were the ancient Egyptians able to know the exact area or position of these stars in order to align each of the three pyramids to them?
Where did astronomy originate? According to the Department of Astronomy, the earliest people to keep astronomical records where the Akkadians (they lived in what is later known as the northern part of Babylon). The earliest date is from around 2,500 B.C. The ancient Akkadian priests were the first to record these astronomical records. They recorded these records because it helped them predict some of the Sun’s motions, and the Earth’s moons, and the stars. These records included observations of the daily, monthly, and yearly positions of the stars and planets. These records explained the geographical locations of the planets. The records also helped with them being able to judge when to plant and harvest crops and with religious ceremonies.