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The biography of Edwin Hubble
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The biography of Edwin Hubble, the legendary astronomer who discovered the extragalactic space
Edwin Powell Hubble known as Edwin Hubble was a famous American astronomer who played an important role in formulating the basic principles of extragalactic and observational astronomy. Historians and astronomy experts consider him one of the most important astronomers in history. Hubble placed the space clouds, which before her time were known as gas and dust particles and were in the category of nebula or nebula, in the category of galaxies.. Historians consider Hubble’s discovery of other galaxies equal to Copernicus’ theory in terms of scientific value. Copernicus proved that the Earth is not at the center of the solar system, and Hubble proved that the Milky Way is not the center of the universe.
One of the important scientific relics of this astronomer is Hubble’s law in space. In short, this law states that the universe is expanding at a constant rate. In addition, in this law, the distance of each galaxy from the edge of the universe is directly proportional to its speed. Of course, this law was discovered two years before Hubble’s presentation by Georges Lemaitre, but its fame came to Hubble. The Hubble telescope is one of the most famous monuments built in the name of this legendary astronomer. An example of this telescope is installed in his hometown of Marshfield, Missouri. This telescope was sent into Earth orbit in 1990 to capture more detailed images of space outside the Milky Way.
Edwin Hubble has another great achievement in the field of cosmology and that is the classification of galaxies. This classification has been used by astronomers for many years. Hubble played a significant role in adding the astronomy category to the Nobel Prize. Of course, the sudden death of this scientist in 1953 prevented him from receiving this award.
Birth and education
Edwin Hubbell was born on November 20, 1889, in Marshfield, Missouri. His mother was Virginia Lee James and his father was John Powell Hubble. His father was a lawyer and insurance businessman. Edwin was the third child out of 8 children in this family. Of course, like many children of those years, some of Edwin’s siblings died in childhood.
Hubbell lived in a rich family that had to migrate many times because of his father’s work style. During these trips, which were generally in cities around Chicago and Illinois, they lived in luxurious houses with many servants. The children of the Hubble family were all brought up with work and responsibility; Because their parents believed that this style of upbringing would increase their sense of responsibility.
Edwin Hubble was very interested in sports as a child and teenager
As a child, Edwin struggled to keep up with his older siblings and students, so he learned to read before school. He was very fond of adventure books by Jules Verne and H. Rider Haggard. Edwin’s grandfather was an amateur but enthusiastic astronomer. At the age of 7, he got acquainted with one of his grandfather’s telescopes and had his first experience of space exploration. The interesting thing is that instead of participating in the celebration, he observed the space with this telescope on his 8th birthday.
Hubble completed his high school education at Wheaton High School near Chicago. He finished high school easily and with excellent grades in English, mathematics, biology, chemistry, physics, Latin, and German languages. Of course, in high school, Edwin was more into sports than studying, and he owed his high grades to his innate intelligence. On his father’s advice, he was busy delivering goods on holidays. Finally, Edwin Hubbell graduated from high school in 1906 at the age of 16 and received a scholarship to the University of Chicago. He worked at this university as a laboratory assistant of the famous physicist Robert Millikan (Nobel Prize winner).
Edwin Hubble (left), with friends after returning from Oxford
After entering the university, sports still occupied a large part of Hubble’s time. He was fond of sports such as basketball and boxing. He was a tall and strong person and he left several records during his university days. Edwin Hubble graduated from the university in 1910 with a bachelor’s degree in general science and honors in physics and astronomy.
After graduating from the University of Chicago, Hubbell entered Oxford University with a Rhodes scholarship and studied there for three years. Hubble was quickly influenced by English culture and changed many of his past behaviors and habits and adopted an English appearance. Contrary to his strong interest in experimental sciences and especially astronomy, he chose the field of law theory out of respect for his father and graduated from Oxford in 1912. He stayed at this university for another year and studied Spanish. While studying at Oxford, Hubble had another achievement including traveling around Europe. In these trips, in addition to having fun, he paid special attention to planning and thinking about his future. In those years, Edwin wrote in a letter to his mother:
Work is pleasant when it is for a great purpose and end. A goal so great that the thought of it and the anticipation of its achievements, will remove all the fatigue of the difficult task. When I find the purpose and principles I want, I leave everything for it and dedicate my life to it.
Edwin’s father died in the fall of 1912. He asked his father for permission to leave Oxford to visit him but was refused. Young Edwin remained in Oxford and his father died in January 1913.
Hubble exploring the cave
His Career
Hubble’s first job was teaching high school Spanish and physics.
Edwin Hubble returned to America in the summer of 1913. He was employed as a Spanish and Physics teacher at New Albany High School in Indiana. In addition, he coached the school’s basketball team and had a part-time job as a German translator. Although Hubble was a popular teacher, he did not enjoy his job. For this reason, he corresponded with Forrest Ray Moulton, professor of astronomy at the University of Chicago, and asked him for advice on collaborating on astronomy projects and higher education in this field. Moulton also introduced Hubble to Edwin Frost, director of the Yerkes Observatory in Wisconsin. In his letter, he introduced Hubble as a hardworking person, enthusiastic about science, and useful to Frost.
Finally, at the age of 24, Edwin entered the field of science, which he had become interested in nearly two decades ago by observing space through the lens of his grandfather’s telescope. Upon entering the observatory, he began his doctoral course in astronomy and received his degree in 1917 with a thesis entitled Photographic Investigations of Faint Nebulae. With the outbreak of World War I, Hubble served in the army for a year and rose to the rank of colonel despite not being actively involved in combat. He then went to Cambridge University to study astronomy.
Edwin Hubble started working at the Mount Wilson Observatory in California in 1919 at the age of 30. This observatory is famous for its excellent weather and excellent observation conditions. These factors made Hubble research in this place until the end of his life.
Hubble membership card in the army
Scientific achievements
As mentioned, Hubble wrote his doctoral dissertation on nebulae. He continued his research at Mount Wilson using the world’s largest telescope, the Hooker telescope. Hubble’s great discoveries, including galaxies beyond the Milky Way and the phenomenon of redshift, were the results of this astronomer’s research using the Hooker telescope.
In 1912, the American astronomer Henrietta Leavitt published an important discovery related to stars called the Cepheid variable. Beginning in the 1930s, Hubble was able to discover similar stars in nebulae using the Hooker telescope. While studying the Andromeda Nebula, he realized that these stars are very far from Earth and much farther than the stars of the Milky Way.
The discovery of other galaxies and the greatness of the universe was the greatest achievement of this scientist
Eventually, Hubble discovered that the Andromeda Nebula is actually a galaxy. Until then, most astronomers believed that the Milky Way and the Universe were a single entity. Hubble discovered that the universe is much larger than the Milky Way and consists of “island universes”. His findings in this historical discovery are summarized as follows:
- His high-quality images of Andromeda and the Triangulum Nebula showed a massive cluster of stars.
- Many of the stars were of the Cephasian type.
- The studied nebula is one million light years away from Earth. 4 times more than all the objects that had been discovered until that time. (Of course, this distance is proven to be equal to 2.5 million light-years today.)
- The diameter of the Andromeda Nebula is 30 thousand light years. (Today, these dimensions have been proven to be 220,000 light years.)
- Andromeda galaxy emits light equal to one billion suns of our system.
Hubble published his findings three days after his 35th birthday. Of course, his discoveries were not published in a scientific journal, but in the New York Times. The results of his research were debated among astronomers for some time, and finally, his paper was reviewed at the meeting of the American Astronomical Society on January 1, 1925. Hubble changed everyone’s view of the universe with his discoveries. He proved that our vast galaxy, host to the Sun and hundreds of billions of similar stars, is only one of the billions of galaxies in the universe.
Andromeda Galaxy
In addition to this discovery, Hubble provided a standard for classifying galaxies that was used by astronomers for years.
Redshift phenomenon
Prominent astronomer Veslu Slifer has also researched nebulae. He stated in his report in 1913 that the light of the nebula tends towards the red color of the color spectrum. He explained his discovery as a form of the Doppler effect. According to the same explanation, the light tends to the red side of the color spectrum as the emission source moves away, similar to the Doppler effect. To test his discovery, Slifer studied many nebulae. He came to the conclusion that the light of many of these nebulae has a fast transition towards red color and as a result, they are moving away from Earth at a high speed.
Hubble stated that galaxies are moving away from each other at high speed
In 1929, using Slifer’s findings and combining them with his own discoveries and his assistant Milton Humson’s, Hubble was able to find an explicable relationship between galaxy distance and redshift state. He recorded his findings in a formula known today as Hubble’s law. This formula is displayed as v = Hr, where v is the velocity, r is the distance, and H is Hubble’s constant. This constant was first named as 530 by Hubble, but today, using advanced research and tools, the exact number is 70.
The world is expanding
One of the main interpretations of Hubble’s law is that we live in an expanding universe. Of course, Hubble himself believed that there is not enough credible evidence to prove this interpretation of the redshift effect. The remarkable point is that although Hubble drew the attention of the scientific community to this law, the law was discovered two years earlier by Georges Lemaitre. In fact, Lemaitre’s interpretation of this law is more accepted by new cosmologists; Because he used Einstein’s law of relativity for his interpretation.
However, Hubble’s point of view was quite logical. He believed that the theory of red shift can only be accepted as a proof of the expansion of the universe when the density of matter in the universe is much higher than the amount discovered up to that time. These statements have been the basic foundations for the proof of dark matter in the universe. Hubble said about the density of materials needed to prove the effect of redshift:
The required density of matter is several times higher than the estimated maximum density of matter concentrated in the nebula. Furthermore, we have no evidence of significant interstellar matter increasing the density.
Classification of galaxies by Hubble
However, although Hubble had a lot of resistance to accept the effect of redshift, in his research he found that the speed of this expansion is slowing down. However, these findings and research on the speed of galaxy expansion are still ongoing and astronomers discover new issues every day.
One of the historical events regarding the theory of the expanding universe is Albert Einstein’s meeting with Edward Hubble in 1931. The two met at Mount Wilson Observatory. In 1917, in his theory of relativity, Einstein considered the universe to be constant and without change in size. He did not see any end or end to the universe. Although his research showed signs of the expansion of the universe, this scientist tried to deny it by determining a constant called the cosmic constant.
However, the January 1931 meeting earned Hubble the nickname of the man who forced the world’s smartest man to change his mind. This meeting caused Einstein to call his previous calculations the biggest mistake of his scientific life, and as a result, Hubble’s findings became the center of attention in scientific circles.
The Big Bang theory is influenced by the findings of this scientist about the expansion of the universe
In 1935, Hubble discovered the 1373 asteroid named Cincinnati. A year later he published the book ” The Realm of the Nebulae “. This book is a historical interpretation of his experiences and research on intergalactic astronomy. With the outbreak of World War II, Hubble once again served in the US Army at the Aberdeen Proving Ground. He was in charge of the ballistics research department in this area. His extensive research resulted in several improvements in the power of ballistic bombs and projectiles. One of his major practical achievements in this research was the improvement of ballistic projectile components, which resulted in a high-speed camera to study the characteristics of the bomb after launch. After the war, Hubble returned to Mount Wilson and spent some time at the Palomar Observatory in California.
Edwin Hubble in old age
In addition to scientific research, Edwin Hubble worked hard to convince the Nobel Prize Society to add astronomy to the award’s branches. He intended to add this science to this event as an independent subsection of physics. He believed that the efforts of astronomers in stellar physics should be appreciated. Unfortunately, after Hubble’s death, this society decided to appreciate this science as a branch of physics.
Personal life and death
Edwin Hubbell married Grace Burke Leib in 1924 at the age of 34 . They had no children. One of Hubble’s pastimes was collecting books. He was generally interested in books related to the history of science. In addition to scientific research, Hubble was also a member of the Board of Trustees of the Huntington Library in San Marino. The discovery of distant galaxies made him so famous that in 1948 his picture appeared on Time magazine. He and his wife had a close relationship with Hollywood stars and artists such as Aldous Huxley.
In 1949, at the age of 59, Edwin Hubbell suffered a heart attack while on vacation in Colorado and was nursed back to health by his wife. Of course, after this incident, the intensity of his research activities decreased until he died on September 28, 1953, due to a blood clot in the brain. He had willed that his burial place should not be known and personal notes were also destroyed by his wife. Grace also died in 1980 and was buried in a secret place next to her husband.
Awards and honors
The Cleveland Newcomb Prize was awarded to Edwin Hubble in 1924. In 1938, he was awarded the Bruce Medal, and a year later, he was awarded the Franklin Medal Science and Engineering Award by the Franklin Institute in Philadelphia. The Gold Medal of the British Royal Astronomical Society was awarded to this legendary astronomer in 1940. The Legion of Honor, which is a military award from the US Armed Forces, was awarded to him in 1946 for his research in the field of ballistics.
Hubble Space Telescope
After the death of Edwin Hubble, in addition to the aforementioned awards, other honors were also registered to pay tribute to this American scientist. The Missouri City Hall of Fame inducted Edwin Hubbell in 2003. In 2008, a commemorative stamp was printed in the name of this scientist, and in 2017, the Indiana Basketball Hall of Fame registered Hubble’s name.
Asteroid number 2069 and a hole in the moon are among the celestial objects that are registered in the name of this scientist. A planetarium at Edward R. Morrow High School in Brooklyn was also named after this scientist, and a street in Missouri was named after Edwin Hubble.
Certainly, the most famous monument of Edwin Hubble is the Hubble Space Telescope, which was launched in 1990. The main purpose of launching this telescope was to accurately calculate Hubble’s constant in his famous formula. Anyway, astronomers with this telescope first considered the number 72 as a constant in 2001, and then in 2006, by studying the microwave background of the galaxy, they reached the exact number 70. In addition, the Hubble telescope made it possible to observe not only the expansion of the universe but also the acceleration of this expansion. Today, the force that caused this expansion is called dark energy in scientific documents.
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Space
Dark matter and ordinary matter can interact without gravity!
Published
7 days agoon
01/10/2024Preposition: For each; per.
Noun: A topology name.
Noun: which has mass but which does not readily interact with normal matter except through gravitational effects.
Adverb: Beyond all others.
Preposition: For each; per.
Noun: A topology name.
Dark matter and ordinary matter can interact without gravity!
Why is dark matter associated with the adjective “dark”? Is it because it harbors some evil forces of the universe or hidden secrets that scientists don’t want us to know? No, it is not. Such fanciful assumptions may sound appealing to a conspiracy theorist, but they are far from the truth.
Dark matter is called dark because it does not interact with light. So when dark matter and light collide, they pass each other. This is also why scientists have not been able to detect dark matter until now; it does not react to light.
Although it has mass and mass creates gravity, this means that dark matter can interact with normal matter and vice versa. Such interactions are rare, and gravity is the only known force that causes these two forms of matter to interact.
However, a new study suggests that dark matter and ordinary matter interact in ways other than gravity.
If this theory is correct, it shows that our existing models of dark matter are somewhat wrong. In addition, it can lead to the development of new and better tools for the detection of dark matter.
Read more: There is more than one way for planets to be born
A new missing link between dark and ordinary matter
Dark matter is believed to have about five times the mass of normal matter in our universe, which helps hold galaxies together and explains some of the motions of stars that don’t make sense based on the presence of visible matter alone.
For example, one of the strongest lines of evidence for the existence of dark matter is the observation of rotation curves in galaxies, which show that stars at the outer edges of spiral galaxies rotate at rates similar to those near the center. These observations indicate the presence of an invisible mass.
Also, for their study, the researchers studied six ultra-dim dwarf (UFD) galaxies located near the Milky Way. However, in terms of their mass, these galaxies have fewer stars than they should. This means they are mostly made up of dark matter.
According to the researchers, if dark matter and normal matter interact only through gravity, the stars in these UFDs should be denser in the centers and more spread out toward the edges of the galaxies. However, if they interact in other ways, the star distribution looks different.
The authors of the study ran computer simulations to investigate both possibilities. When they tested this for all six ultra-dim dwarf (UFD) galaxies, they found that the distribution of stars was uniform, meaning that the stars were spread evenly across the galaxies.
This was in contrast to what is generally observed for gravitational interactions between dark matter and normal matter.
What causes this interaction?
The results of the simulations showed that gravity is not the only force that can make dark matter and normal matter interact. Such an interaction has never been observed before, and it could change our understanding of dark matter and dark energy.
However, this study has a major limitation. What caused the interaction between the two forms of matter is still a mystery. While the current study provides tantalizing hints of a novel interaction, its exact nature and underlying causes remain unknown. Hopefully, further research will clarify the details of such interactions.
This study was published in The Astrophysical Journal Letters.
Space
James Webb Space Telescope deepens cosmology’s biggest controversy
Published
2 weeks agoon
26/09/2024How the James Webb Space Telescope deepens cosmology’s biggest controversy
Summary of the article:
- Almost a century ago, Edwin Hubble discovered the expansion of the universe and calculated the expansion rate or the cosmic constant.
- Since Hubble, many groups have tried to measure the expansion rate of the universe. However, the values they obtained differed from the theoretical predictions. This difference is called Hubble tension.
- Scientists today use three methods to measure the expansion rate of the universe: Cephasian variable stars, TRGB red giant stars, and JAGB asymptotic giants.
- However, the Hubble tension still exists, indicating that the methods for calculating the Hubble constant suffer from a systematic flaw.
- Researchers hope to be able to use the James Webb telescope in the coming years to achieve more accurate measurements of the universe’s expansion rate and thus resolve the Hubble tension.
Almost a century ago, Edwin Hubble discovered that the universe was getting bigger. However, today’s measurements of how fast the universe is expanding are contradictory. These discrepancies show that our understanding of the laws of physics may be incomplete. On the other hand, everyone expected the sharp eyes of the James Webb telescope to bring us closer to the answer to the riddle; But a new analysis of the telescope’s long-awaited observations once again reflects inconsistent expansion rates from different types of data, while pointing to possible sources of error.
Two competing groups have led efforts to measure the rate of expansion of the universe, known as Hubble’s constant, or H0. A group led by Adam Reiss of Johns Hopkins University, relying on the known constituents of the universe and the governing equations, has consistently calculated the Hubble constant to be approximately 8 percent higher than the theory predicts the universe’s expansion rate. This discrepancy, known as the Hubble tension, indicates that the model of the cosmological theory may have missed some elements such as raw materials or effects that speed up the expansion of the universe. Such an element can be a clue to a more complete understanding of the world.
This spring, Reiss and his team published new measurements of the Hubble constant based on data from the James Webb Telescope and found a value consistent with their previous estimates. However, a rival group led by Wendy Friedman of the University of Chicago warns that more precise measurements are needed. The team’s measurements of the Hubble constant are closer to the theoretical estimate than Riess’ calculations, suggesting that the Hubble stress may not be real.
Since the commissioning of the James Webb Telescope in 2022, the astrophysical community has been waiting for Friedman’s multidimensional analysis based on telescope observations of three types of stars. The results are now as follows: the two-star types provide estimates of the Hubble constant that are in line with the theoretical prediction; While the results of the third star, which is the same type used by Reiss, are consistent with his team’s higher estimates of Hubble’s constant. According to Friedman, the fact that the results of the three methods are contradictory does not mean that there are unknown physical foundations, but that there are some systematic errors in the calculation methods.
Contradictory world
The difficult part of measuring cosmic expansion is measuring the distance of space objects. In 1912, American astronomer Henrietta Levitt first used pulsating stars known as Cephasian variables to calculate distances. These stars flicker at a rate proportional to their intrinsic luminosity. By understanding the luminosity or radiant power of a Cephasian variable, we can compare it with its apparent brightness or dimming to estimate its galaxy’s distance from us.
Edwin Hubble used Levitt’s method to measure the distances to a set of galaxies hosting the Cephasian variable, and in 1929 he noticed that the galaxies that are farther away from us are moving away faster. This finding meant the expansion of the universe. Hubble calculated the expansion rate to be a constant value of 500 km/s per megaparsec. In other words, two galaxies that are 1 megaparsec or approximately 3.2 million light years apart are moving away from each other at a speed of 500 km/s.
As progress was made in calibrating the relationship between the pulsation frequency of Cepheids and their luminosity, measurements of the Hubble constant improved. However, since the Cephasian variables are very bright, the whole approach used has limitations. Scientists need a new way to measure the distance of galaxies from each other in the infinite space.
In the 1970s, researchers used Cephasian variables to measure the distance to bright supernovae, and in this way they achieved more accurate measurements of the Hubble constant. At that time, as now, two research groups undertook the measurements, and using supernovae and Cephasian variable stars, they achieved contradictory values of 50 km/s per megaparsec and 100 km/s per megaparsec. However, no agreement was reached and everything became completely bipolar.
Edwin Hubble, the American astronomer who discovered the expansion of the universe, stands next to the Schmidt telescope at the Palomar Observatory in this photo from 1949.
The launch of the Hubble Space Telescope in 1990 gave astronomers a new and multi-layered view of the universe. Friedman led a multi-year observing campaign with Hubble, and in 2001 he and his colleagues estimated the expansion rate to be 72 km/s/Mpa with an uncertainty of at most 10%.
A Nobel laureate for the discovery of dark energy, Reiss got into the expansion game a few years later. In 2011, his group found the Hubble constant to be 73 with a three percent uncertainty. Soon after this, cosmologists excelled in another way. In 2013, they used Planck’s observations of light left over from the early universe to determine the exact shape and composition of the early universe.
In the next step, the researchers connected their findings to Einstein’s theory of general relativity and developed a theoretical model to predict the current state of the universe, up to approximately 14 billion years into the future. Based on these calculations, the universe should be expanding at an approximate rate of 67.4 km/s per megaparsec with an uncertainty of less than one percent.
Reese’s team measurement remained at 73, even with the improved accuracy. This higher value indicates that the galaxies today are moving away from each other at a faster rate than theoretically expected. This is how the Hubble tension was born. According to Reiss, today’s Hubble tension shows us that something is missing in the cosmological model.
The missing factor could be the first new element in the universe to be discovered since dark energy. Theorists still have doubts about the identity of this agent. Perhaps this force is some kind of repulsive energy that lasted for a short time in the early universe, or perhaps it is the primordial magnetic fields created during the Big Bang, or perhaps what is being missed is more about ourselves than the universe.
Ways of seeing
Some cosmologists, including Friedman, suspected that unknown errors were to blame for Hubble’s tension. For example, Cephasian variable stars are located in the disks of younger galaxies in regions full of stars, dust, and gas. Even with Hubble’s fine resolution, you don’t see a single Cephasian variable, according to George Afstatio, an astrophysicist at the University of Cambridge. Rather, you see it overlapping with other stars. This density of stars makes measurements of brightness difficult.
When the James Webb Telescope launches in 2021, Reiss and his colleagues will use its powerful infrared camera to peer into the crowded regions that host the Cephasian variables. They wanted to know whether the claims of Friedman and other researchers about the effect of the area’s crowding on the observations were correct.
The 6.5-meter multi-section mirror of the James Webb Space Telescope at NASA’s Goddard Space Flight Center in Maryland. This mirror passed various test stages in 2017.
When the researchers compared the new numbers to distances calculated from Hubble data, they saw a surprising match. The latest results from the James Webb telescope confirmed the Hubble constant measured by the Hubble telescope a few years ago: 73 km/s/Mpa with a difference of one kilometer or so.
Concerned about crowding, Friedman turned to alternative stars that could serve as distance indicators. These stars are found in the outer reaches of galaxies and away from the crowd. One of those stars belongs to the group ” Red Giant Branch ” or TRGB for short. A red giant is an old star with a puffy atmosphere that shines brightly in the red light spectrum. As a red giant ages, it eventually burns helium in its core, and at this point, the star’s temperature and brightness suddenly decrease.
A typical galaxy has many red giants. If you plot the brightness of these stars against their temperature, you reach a point where the brightness drops off. The star population before this brightness drop is a good distance indicator; Because in each galaxy, such a population has a similar distribution of luminosity. By comparing the brightness of these star populations, astronomers can estimate their relative distances.
The Hubble tension shows that the standard model of the cosmos is missing something
Regardless of the method used, physicists must calculate the absolute distance of at least one galaxy as a reference point in order to calibrate the entire scale. Using TRGB as a distance index is more complicated than using Kyphousian variables. MacKinnon and colleagues used nine wavelength filters from the James Webb telescope to understand how brightness relates to their color.
Astronomers are also looking for a new indicator: carbon-rich stars that belong to a group known as the “Jay region asymptotic giant” (JAGB). These stars are far from the bright disk of the galaxy and emit a lot of infrared light. However, it was not possible to observe them at long distances until James Webb’s launch.
Friedman and his team have applied for observation time with the James Webb Space Telescope in order to observe TRGBs and JAGBs, along with more fixed spacing indices and Cephasian variables, in 11 galaxies.
The vanishing solution
On March 13, 2024, Friedman, Lee, and the rest of the team meet in Chicago to find out what they’ve been hiding from each other. Over the past months, they were divided into three groups, each tasked with measuring distances to 11 galaxies using one of three methods: Cephasian variable stars, TRGBs, and JAGBs.
These galaxies also host related types of supernovae, so their distances can calibrate the distances of supernovae in many more distant galaxies. The rate at which galaxies move away from us divided by their distance gives the value of the Hubble constant.
Wendy Friedman at the University of Chicago is trying to fit the James Webb Telescope observations into the Standard Cosmological Model.
Three groups of researchers calculated distance measures with a unique, random counterbalancing value added to the data. During the face-to-face session, they removed those values and compared the results.
All three methods obtained similar distances with three percent uncertainty. Finally, the group calculated three values of Hubble’s constant for each distance index. All values were within the theoretical prediction range of 67.4. Therefore, Hubble’s tension seemed to be resolved. However, they ran into problems with further analysis to write the results.
The JAGB analysis was good, But the other two were wrong. The team found that there were large error bars in the TRGB measurements. They tried to minimize the errors by including more TRGBs; But when they started doing this, they found that the distance to the galaxies was less than they first thought. This change caused the value of Hubble’s constant to increase.
Friedman’s team also discovered an error in Cephaus’s analysis: in almost half of the pulsating stars, the term crowd was applied twice. Correcting this error increased the value of Hubble’s constant significantly. Hubble’s tension was revived.
Finally, after efforts to fix the errors, the researchers’ paper presents three distinct values of Hubble’s constant. The JAGB measurement yielded a result of 67.96 km/s/megaparsec. The TRGB result was equal to 69.85 with similar error margins. Hubble’s constant was obtained at a higher value of 72.05 in the Kyphousian variable method. In this way, different hypotheses about the characteristics of these stars caused Hubble’s stress value to vary from 69 to 73.
By combining the aforementioned methods and uncertainties, the average Hubble stress value equal to 69.96 was obtained with an uncertainty of four percent. This margin of error overlaps with the theoretical prediction of the expansion rate of the universe, as well as the higher value of Tim Reiss.
Tensions and resolutions
The James Webb Space Telescope has provided methods for measuring the Hubble constant. The idea is simple: closer galaxies look more massive; Because you can make out some of their stars, while more distant galaxies have a more uniform appearance.
A method called gravitational convergence is more promising. A massive galaxy cluster acts like a magnifying glass, bending and magnifying the image of a background object, creating multiple images of the background object when its light takes different paths.
Brenda Fry, an astronomer at the University of Arizona, is leading a program to observe seven clusters with the James Webb Space Telescope. Looking at the first images they captured last year of the G165 cluster, Fry and his colleagues noticed three spots that were not previously seen in the images. These three points were actually separate images of a supernova that was located in the background of the aforementioned cluster.
After repeating the observation several times, the researchers calculated the difference between the arrival times of the three gravitational lensing images of the supernova. This time delay is proportional to Hubble’s constant and can be used to calculate this value. The group obtained an expansion velocity of 75.4 km/s/Mpa with a large uncertainty of 8.1%. Fry expects the error bars to correct after several years of similar measurements.
Both Friedman’s and Reiss’ teams predict that they will be able to get a better answer with James Webb’s observations in the coming years. “With improved data, the Hubble tension will eventually be resolved, and I think we’ll get to the bottom of it very quickly,” Friedman says.
James Webb vs. Hubble; Comparing the images of two space telescopes
The James Webb Space Telescope is now the flagship of the world of space telescopes. James Webb uses the largest mirror of any telescope launched into space and orbits the Sun at a distance from Earth (approximately 1.5 million kilometers). This telescope is supposed to make a big change in astronomy and astrophysics by looking at the farthest parts of the world and unveiling new secrets.
However, in the past three decades, the Hubble Space Telescope has been the main player in the field of space telescopes. Launched in 1990, this telescope has recorded many epic images of planets, stars, galaxies, nebulae and many other astronomical wonders.
Since Hubble was in near-Earth orbit, it could take accurate pictures of the universe without the Earth’s atmosphere interfering with its operation. The telescope captured amazing images during its prolific career and continues to serve its mission. According to NASA, over the past 32 years, Hubble has made 1.5 million observations and contributed to more than 19,000 scientific papers.
Now James Webb is going to take the flag from Hubble and further enhance our understanding of the universe. In a blog post comparing the two space telescopes, NASA called James Webb the “scientific successor” to Hubble. Without Hubble’s observations of the cosmos, researchers would not have prioritized building a telescope that could go beyond Hubble’s field of view. Continue with Zoomit to have a closer look at the images of celestial targets in both telescopes.
Deep field
The top right photo is the deep Hubble wallpaper taken in 1995 and released in 1996. At the time of recording, this photo was considered the deepest image taken of the universe. In order to make it, the researchers took 342 photos during 10 days with a total of 100 hours of exposure. The final result revealed more than three thousand scattered galaxies in a very small part of the sky. Over the next few decades, Hubble operators took better pictures of this type and looked much deeper into space.
The Hubble Ultra Deep Image or XDF was released in 2012.
The photo above is the Hubble Ultra Deep Wallpaper released in 2012. More than 5500 galaxies are visible in this photo. Over the course of a decade, the researchers collected 50 days of observations from a concentrated area, resulting in two million seconds of exposure (over 23 days).
Then along came James Webb. The first full-color scientific photo by James Webb was released on Tuesday morning Iran time by US President Joe Biden as a preview for the first set of telescope images. While capturing Hubble’s deep fields required days, if not weeks, of exposure, James Webb managed to capture this image after just 12.5 hours of exposure.
The recorded area of the sky in the image above is incredibly small; So small that it is about the size of a grain of sand on a person’s hand on the ground. In that part of the sky, a galaxy cluster called SMACS 0732 is located 4.6 billion light-years away. This cluster is so large that it bends space-time around it and, like a cosmic microscope, reveals faint galaxies far behind it. Some of these galaxies are considered to be the faintest infrared objects ever observed, and scientists are eagerly waiting to learn more about them.
Shahabhi Nebula (Karina)
The image above shows one of Hubble’s most popular targets, the Carina Nebula, at a distance of 7,200 light years from us. The image on the right, released by the Hubble Heritage Project in 2008, shows part of the star-forming region in the corner of the nebula.
The picture looks like an impressionist landscape with hills, valleys, and columns of gas and dust scattered around, with only a few bright stars behind the nebula. Now James Webb’s updated image shows the same stunning landscape in much greater detail and clarity. In the photo, there are stars that were previously hidden behind gas and dust.
Read more: Why is Jupiter one of the first targets of the James Webb Space Telescope?
Stephan’s quintuplets
This group of five galaxies is stunning in a Hubble image taken in 2009 after the telescope’s camera was upgraded earlier that year. That year, the space shuttle made its fifth and final visit to Hubble and applied a major upgrade. In addition to the new camera that took this photo, the telescope was also upgraded and repaired. The ability of astronauts to rendezvous with Hubble in near-Earth orbit kept the space telescope operational for a very long time.
However since James Webb is so far from Earth, he will not have the advantage of meeting astronauts. However, the spacecraft has enough fuel for at least 20 years; This means that in the future we will see many more images like the one above.
The photo above shows a group of galaxies that were first observed in 1877. The upper left galaxy is considered the alien mass of the group and is much closer to Earth than the other four members. However, the other four galaxies are so close that James Webb can see the shock waves from the interaction between them as they kill each other.
Stephen’s quintuplet is the largest image taken by the James Webb Telescope and is actually a mosaic made up of more than a thousand separate images captured by the telescope’s two instruments: the Near Infrared Camera (NIRCam) and the Mid-Infrared Instrument (MIRI). Both cameras collect infrared wavelengths of light and help James Webb see through gas and dust; But as their names suggest, both collect different wavelengths of infrared light.
Southern Ring Nebula
The last image is the Southern Ring Nebula, which was imaged by Hubble in 1998. The “ring” is the dying star particles (the faintest of the two bright spots in the center of the image). The little white dwarf causing all this chaos was a star the size of our Sun. At some point, the star ran out of fuel and ejected its outer layers, creating the ring seen in the image. The diameter of the ring is about half a light year and the gases are moving outward at a speed of nearly 14.5 km/s.
On the left, the Southern Ring Nebula is seen through the eyes of James Webb’s two instruments, Nirkem and Miri. The image we have chosen for comparison was captured by Nirkam’s near-infrared camera. Another version of the image is also recorded in mid-infrared.
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