Hertzsprung-Russell Diagram

File:Milky Way Galaxy.jpg

Matt William’s article, “Thanks to a Massive Release from Gaia, We Now Know Where 1.7 Billion Stars are in the Milky Way,” talks about the mission which would “create the largest and most precise 3D catalog of the Milky Way.” The mission includes taking a look at “positions, distance indicators, and motions of more than a billion stars,” asteroids, and “even some stars beyond” our galaxy. Hertzsprung-Russell Diagrams will help astronomers determine the population, age, location, and formation of stars in our galaxy. The Gaia mission will give astronomers more accurate measurements if the mission extension takes place.

As mentioned in the article with the Gaia mission, astronomers will be using the Hertzsprung-Russell Diagram (more advanced than the one below) to get more information regarding the stars in our galaxy.


The article relates to our lecture tutorial (image above) because using the diagram one can identify the types of stars, luminosity, absolute magnitude, and temperature.

The article was interesting and showed me that astronomers do use the diagram to make new discoveries. I won’t be an astronomer, so I will never use the diagram, but at least I will be able to read one.


Star Formation. . . and more!

Stars come into being in dense molecular clouds within galaxies. These clouds of dust and gas obscure the early stages of stellar formation from optical telescopes. Luckily, recent developments in radio and infrared astronomy now permit astronomers to examine inside these clouds and acquire a better perception of the processes concerned with star birth. Computationally exhaustive computer replications also grant them to sculpt the processes and asses the results counter to observations.

Gravity is the force in authority for stellar formation and the mass of material that forms at star principally governs its life and fate.

Next is Interstellar medium. According to the lecture, this is where the atoms are widely spaced, about 1 molecule per cm3, a nearly perfect vacuum (3×1019 molecules/cm3 for air). The temperature is cold, less than 100K. As for interstellar clouds, they are primarily composed of H and He. These can be very hot and are not photogenic. Molecular clouds start off cool and are made of complex molecules. Then, the cloud collapses where parcels of gas within a molecular cloud feel the gravitational attraction of all other parts of the molecular cloud leading to a net gravitational force toward the cloud center.

Besides, I feel the lecture tutorial on “Star Formation and Lifetimes” explains this in simpler terminology. Stars begin life as a cloud of gas and dust. The birth of a star begins when a disturbance, such as the shock wave from a supernova, triggers the cloud of gas and dust to collapse inward. For instance, imagine that you are observing the region of space where a cloud of gas and dust is beginning to collapse inward to form a star, the object that initially forms in this process is called a protostar. In this case, the atoms will move closer one another. But, the physical interaction that causes the atoms to move closer is gravitational forces.

Additionally, how can we study star formation? Through Nebula or HII diagram. Nebulae are merely clouds of interstellar gas and dust which give the impression either as dark regions tarnishing out background stars – the so-called dark or absorption nebulae or as brighter clouds of gas that emanate or reflect light. They are the most perceptible mechanisms of the interstellar medium.

But, what does this all mean? What is its effect on research? In the article “New Planets May Be Forming Around Young Nearby Stars, Dusty Disks Suggest” Samantha Mathewson states, “Diverse disks of dusty material have been spotted around nearby young stars, suggesting new planets are sprouting up around the alien stars. . . specifically, the disks are seen around nearby young stars and contain gas, dust, and planetesimals which combine to form developing planets. Researchers have observed a remarkable variety of these disks, differing in size, shape and structure, according to a statement from ESO. . . Despite this proximity, it can be difficult to study the protoplanetary disks surrounding these stars because the bright light from the parent star itself often outshines the faint reflected light from the disks. However, the researchers were able to get a detailed view of the dusty disks using the SPHERE [Spectro-Polarimetric High-contrast Exoplanet Research] instrument, which blocks the bright light of nearby stars to reveal the regions surrounding them.” In essence, star formation and study of stars provides astronomers avenues through which they expand their research in different fields of science.

This subject matter was rather difficult to comprehend. I assumed since it had something to do with star formation which seems to be a prime target in contemporary research, I would perceive the content better. Although, there is nothing specific that I feel iffy about, something is still unclear. I guess that testifies to the intricacies of this topic. I hope to grasp a better understanding of this as our discussion on stars continues.


Grave-robbing stars

Over the past couple of weeks, my astronomy class as been going over the life cycle of stars. We’ve roughly touched up on how they’re formed, what determines what “type” of star they are and how that affects their life span, and we’ve recently discussed what happens when they die. And their deaths can be an interesting spectacle depending on the circumstances. For example, when a Red Giant dies (if its size is lower than a certain point), it will produce something called a Planetary Nebula and end up leaving its core behind as a White Dwarf star. Or if it is larger than said certain point it will explode as a supernova and become either a Neutron Star or a Black hole. Whatever the results, it sounds like something very interesting to see, so long as no astronauts somehow just happen to be too close when it happens.

The thing is that stars die when they run out of fuel (namely Helium and Hydrogen) to keep burning. And it turns out that this particular process can be hurried along as stars are actually capable of robbing each other of said fuel. That is the case of the article “Stellar thief is the surviving companion to a supernova”, posted to Phys.org by Ann Jenkins on April 26, 2018. The article states that when two stars (typically binary stars that are somewhat “close” to each other already) are brought close enough to each other by their orbits, they will interact and transfer gasses from one to the other. And that is exactly what happened. Before one star went supernova, its binary companion had actually siphoned off almost all of the former’s hydrogen from its “stellar envelope”. This envelope, according to the article, is the region that transfers energy from a star’s core to its atmosphere. And the hydrogen theft created an instability in the envelope that did not exactly help the primary star’s life span. I honestly never would have guess that stars were technically capable of stealing from each other. To think that this could possibly happen to the Earth’s sun if it actually had a binary companion. That’s something of a scary thought.

Stellar thief is the surviving companion to a supernova

Objective 13

In the article “Main sequence stars” by Nola Taylor Redd, Redd starts off by saying “stars start their lives as clouds of dust and gas.” Gravity draws these clouds together and a small protostar forms, powered by the collapsing material. Smaller bodies with less than 0.08 of the suns mass cannot reach the stage of nuclear fusion at their core. Instead they become brown dwarfs, stars that never ignite. Stars with sufficient mass, the collapsing gas and dust burns hotter, eventually turning the star into a main sequence star powered by hydrogen fusion. While the sun will spend 10 billion years on the main sequence, a star with 10 times as massive will stick around for only 20 million years. A main sequence star burns through the hydrogen in its core reaching the end of its cycle.

In class we learned that stars produces its energy by nuclear fusion. We also did pages 119-120 that discusses how mass affects the rate of nuclear fusion within a star. I learned how smaller stars will have a longer life span. Also I learned that what affects a star is its temperature and size are affected by the mass. We did lecture tutorial, PowerPoints, and clicker questions to help us understand objective 13 more.

The article was extremely easy to read and understand. If i wasn’t to not take the class, the article was able to give me a back ground on how a star develops and when the star goes to an end. This taught me that nothing lasts forever. Just how in life and even in space, live and die. It’s a life cycle. This article also related to an astro journal I wrote awhile ago talking about how a star cheated death, it had me questioning does stars in space ever come to an end? Now that I’m looking back at it, I am able to explain why it cheated death, and also yes, stars do come to an end.


What’s Going On With The Rarest Stars In The Universe?

This article explains the regular formation of stars, but how many stars do not follow the same pattern of star formation. Stars typically arise from the collapse of a molecular cloud of gas. The cloud fragments form a variety of stars, but they all fuse hydrogen into helium, creating the nuclear energy that powers them. These stars follow the same stellar evolution. However, as scientists discover more and more stars, they are finding that many of them break the rules. Some supermassive stars collapse directly into black holes without a supernova, some binary stars steal mass off of one of their members, some show extremely rare flaring behavior. Some stars are made completely from clouds of gas, composed only of hydrogen and helium. While scientists have been able to explain the basic formation and life of stars, many of them break the rules.

In class, we are learning about the lives of stars. Objective 13 focuses on their formation. The above article talks about what we learned in class about their formation. Our powerpoint taught us about molecular clouds and how they collapse to bring about nuclear fusion. In the lecture tutorial on page 120, we also learned how smaller stars have longer lifetimes. The article mentions an interview with an astronomist who discusses these topics about the lives of stars. She also mentions that although this is the general system for the formation of stars, there are also rare stars that break the rules. However, that is nothing to worry about, because space does not always follow the same equations. It is interesting to see how scientists are still able to explain principles of astronomy like star formation when there are so many exceptions to the rules.


Star By Star

In the article, “Star Facts: The Basics of Star Names and Stellar Evolution.” by Charles Q. Choi he talks about many facts about stars in our Galaxy. He describes stars as “giant, luminous spheres of plasma.” There are billions of stars including out own sun and Milky Way. Not only that but there are billions of Galaxies in out universe. Many of them have planets orbiting them. He then goes on to talk about the history of observing stars, and naming stars. He also talks about star formation, “star develops from a giant, slowly rotating cloud that is made up entirely or almost entirely of hydrogen and helium.” Then talks a lot about characteristics of stars. The brightness of stars is measured by magnitude and luminosity. the brightness affects how many stars that we can see from Earth. The color of the stars can be reddish to yellowish to blue depending the surface temperature. The Surface Temperature is measure in kelvin and the temperature of zero kelvin, equaling minus 273.15 degrees Celsius, or minus 459.67 degrees Fahrenheit. The size of the start affects the brightness of the star. The mass of the star affects the surface temperature of the star. The magnetic field is created by stars being spinning balls of roiling, electrically charged gas fields.

This article relates to objective 13 because this article talks all about stars. In class we talked about stars and how their size and temperature are affected by the mass of the star. It also covers how stars are formed like we talked about in class.

I honestly like this article a lot, I found all the content very interesting. It expanded on what we talked about in class. I learned how they name all the stars in the galaxy, which is a very cool information to know and tell people.

Source: https://www.space.com/57-stars-formation-classification-and-constellations.html

Conceptual Objective 11

In conceptual obj. 11 I learned how astronomers study the process of stars, including: distance, mass and size. I learned that stars orbit center of mass. Stars move in elliptical orbits. Equal areas in equal times. Not all binary stars can be resolved into two stars. Also, I learned that spectroscopic binaries use doppler shift to determine size of stars. I also learned that the apparent magnitude scale was developed by Hipparchus in 120 BC. The catalog of 120,000 stars up to 500 ly. The apparent magnitude chart ranks stars from brightest(1) to faintest (6). The absolute magnitude is used to measure the brightness of object =s that are 10 light years away.

In class we completed two lecture tutorials. The first tutorial was over the Apparent and Absolute magnitude of Stars on pages (33-35). In this lecture tutorial I learned how to determine a stars brightness and I learned how to determine the magnitude of stars and how certain stars are bigger or smaller based on their magnitude.The second lecture tutorial was over The Parsec on pages (37-39). In this tutorial I learned how to determine the position of stars in the sky, what a parsec is, and I learned about the distances between stars.

A recent news article that relates to the apparent or absolute magnitude of stars can be found at,  https://phys.org/news/2018-04-powerful-flare-m-dwarf-star.html . This article describes how astronomers found a powerful solar flare on a M-dwarf star. They also found the absolute magnitude of the star and how many light years the star is away from Earth. This article was very interesting, I never knew about the M-dwarf star until I looked over this article.

This objective was very interesting to learn, I learned a lot about the parsec and the apparent and absolute magnitude.