Of Stars, Superstars and Barbra Streisand

A Star is Born

On a cloudless night, with the naked eye, we should be able to see about two thousand stars illuminating our dark sky like twinkling lights fixed in position on a hemi-spherical canvas that stretches all around, and overhead, from horizon to horizon. How ironic that we are able to gaze at so many stars that preside over other planetary systems and yet, to see the star and ruler of our Solar System, the Sun, we have to wait until the daylight hours and even then, we are mainly aware of its presence through the light and radiated warmth that we receive. We are also unable to look directly at it when it’s at its brightest or highest lest we hurt our eyes. So, our visual appreciation of the “star” of our System is limited. Perhaps the stamps that I present  below provides some idea of its magnificence.

A series of stamps from Sierra Leone - a country in the continent of Africa showing
our magnificent Sun, ruler of the Solar System

In my last post, I wrote at length about the Big Bang model. I had in my mind an idea that a logical follow on to that post would be an article about stars – specifically how a star is born. The formation of the early stars, called primordial stars, was an important development in the evolution of our Universe.

When I started framing my thoughts about how “a star is born”, I found myself switching from the astronomical channel that was initially playing in my mind and instead, comfortably focusing my thoughts on the movie, “A Star Is Born” that was first filmed in 1937 and remade three times in the English language. Bollywood also played a role in enhancing its popularity and it was remade (unofficially) in Hindi, Tamil, Telugu and Nepali between 1973 and 2020. The image of Barbra Streisand and the sound of her voice, singing some of the many hits I have repeatedly listened to, returned quickly to mind and it was then difficult to retune my intellectual faculties to the astronomical dimension until a few words had been committed to paper on the cinematographic version of “A Star Is Born”. 

Indeed, the four versions of this movie filmed in the English language received a total of, no less than, twenty-five nominations for various Academy Awards (but winning only in three categories) with Barbra Streisand (1977) and Lady Gaga (2018) amongst those honoured with Oscars. 

Wikipedia reports that Barbra Streisand was named “Barbara Joan Streisand” at birth but she seems to be more widely known as “Barbra Streisand”. In fact, her albums name her as such. In the case of Lady Gaga, things are a little different. She was born “Stefani Joanne Angelina Germanotta”. There are several anecdotes as to how “Lady Gaga” was fashioned as her stage name but let’s just say she must feel that things have turned out very well. 

Returning to the various remakes of the movie, I did not watch the recent 2018 version of the film which featured Lady Gaga and Bradley Cooper, but I did (very much) enjoy the music and story-line of the 1976 remake, which starred Streisand and Kris Kristofferson. I do not generally keep myself updated with the activities of the stars of the silver screen, but I do recall Barbra Streisand securing some of my musical attention sometime in 2016 with her song, “Don’t lie to me”. I remember thinking straight away that this was a brave piece of music. If you have not heard the song, perhaps this link could be helpful (press Ctrl and click to follow the link):

https://www.youtube.com/watch?v=kNrj87Q-4Yk

Let me now switch back to the astronomical segment of my brain and try to write about the stars that do not reside in Hollywood or Bollywood but instead orbit the centers of their respective galaxies located in deep space. I do not promise to be able to keep entirely on the track of writing about the solar giants and dwarfs as catchy songs from the various movies do keep returning to mind and a quick wander to Youtube is always only a couple of clicks away. But I shall try to remain focused.

Before the Birth of the First Star

I would like to address the subject of how stars came into being mostly because life as we know it would not be possible without the heat and light that emanates from a star. To make it a little more interesting and instructive, I will try to tackle this subject from the angle of how the very first stars came into being and analyse the critical role played by these early stars in the subsequent evolution of our Universe.

Our story starts during the Planck Epoch (or Planck Era). This is the earliest period of time in the history of the Universe, from time is equal to zero seconds until time is approximately 1 X 10 to the power of −43 seconds (Planck time). It is believed that due to the extraordinarily small scale of the Universe at the time, quantum theory (proposed by Max Planck in 1900), explains the nature and behaviour of matter and energy at the atomic and subatomic level, and thus it is this approach that has been accepted, and prevails. It should be noted that the Planck Epoch is the closest that current physics can get to the absolute beginning of time. At this earliest of times after the Big Bang, the Universe is thought to be incredibly hot, dense and turbulent. Everywhere in the infant Universe it’s mostly the same with some very minor density fluctuations also present.

A stamp from Germany,  honouring Max Planck. He developed quantum theory in 1900. 

A great deal continues to happen in the subsequent tiny fractions of the first second, a key phenomenon being cosmic inflation, which sets the foundation for the shape and structure of the Universe that we observe today. During this period of cosmic inflation, which lasted only a tiny fraction of a second, the Universe swelled from a size smaller than that of an electron, to nearly its current size. The inflation model was first proposed by physicist, Alan Guth, in 1980, as one way to explain two problems in cosmology which could not be properly answered by the Big Bang model – the so called “horizon” problem and the “flatness” problem but I shall not delve into these areas in this post (which I was hoping would focus more on the movies and music of Barbra Streisand !). Suffice to say at this stage that the cause of cosmic inflation remains an open question. 

Initially, the Universe is only permeated by energy, but by about one hundredth of a second after the beginning of time, it is estimated that the temperature of the Universe is approximately a hundred thousand million (1 X10 to the power 11) degrees Centigrade. At these unimaginably high temperatures, only elementary particles (currently thought to be the fundamental fermions as well as the fundamental bosons) can survive and these are believed to have been present together with the “energy” of the Universe. These elementary particles and energy all existed in an ionised, white - hot “cosmic soup” or plasma. Electrons and photons which are part of the families of the fundamental fermions and fundamental bosons respectively were also present in this hot plasma. 

Using the Large Hadron Collider ("LHC"), physicists at CERN attempt to identify the elementary particles that were present at the beginning of the Universe. This stamp from Grenada, an island country in the Caribbean shows a picture of the LHC.

During this phase, in simple language, the Universe was virtually “clogged” with high energy particles (with the scattering of photons (of all wavelengths) off the large number of free electrons that were present). Light was present but it was unable to get through the plasma, making the “very early Universe” an opaque, dark place. This (literally) dark phase of the Universe would initially prevail for about 370,000 years. 

During these 370,000 years, the Universe continued along its path of expansion and cooling and the elementary particles gradually evolved into junior members of the sub-atomic family. The minor density variations that were present in the infant Universe now play an important role in a process called “clumping” which was also concurrently taking place. Driven by gravity, matter started accumulating or “clumping” in the parts of the Universe that were initially dense, with less matter remaining in the other less dense areas. As more and more matter clumped in an area, gravity increased, attracting even more and more material. 

It is clumping that eventually results in the existence of  galaxies and the vast voids that we observe today.

The Handwriting of God 

We know that “clumping”, such a critical phenomenon in the formation of stars, occurred at an early period in the evolution of the Universe primarily as a result of the endeavours of an American cosmologist, George Smoot. 

Recall, the reference in my previous post relating to the discovery of the “cosmic microwave background radiation” (“CMBR”) by Penzias and Wilson in the 1960s which won a Nobel Prize in the mid-eighties. The CMBR is the oldest relic that astronomers had of the early Universe. Whilst the discovery by Penzias and Wilson was adequate to irrefutably support the Big Bang model, it was not able to answer the question of why galaxies exist in some parts of the Universe and vast voids prevail elsewhere.

Was there a method to rely on the CMBR for further information that would show clumping as an early Universe phenomenon? George Smoot of the University of California was convinced that there might be further clues in the CMBR but he quickly concluded that moisture found in the atmosphere of Earth would mask the very small variations in the CMBR data that he was trying to measure, if it was gathered terrestrially. To overcome the moisture problem, he initially secured microwave detectors to helium balloons and released them but these experiments mostly ended disastrously. 

In 1976, he again tried to secure precise readings using an aircraft flying at a very high altitude but the design of this experiment was fundamentally flawed. The movement of the aeroplane relative to the rotation of Earth impacted the quality of his results, rendering this approach unreliable. It was soon becoming clear to Smoot that only measurements obtained from space would potentially provide any data of utility.  Demonstrating a great deal of perseverance and tenacity, he became part of an initiative that successfully secured funding from the National Aeronautics and Space Administration (“NASA”) and in 1982, the Cosmic Background Explorer Satellite (“COBE”) project got underway. In simple language, the mission was to thoroughly map the skies and seek out minor differences in CMBR levels thus showing density variations in our early Universe. This satellite was scheduled for launch from one of the Space Shuttle missions but on that fateful cold morning of 28 January 1986, the Space Shuttle Challenger exploded shortly after lift-off with fatal consequences for the entire crew. All Shuttle missions were halted until investigations into this national disaster were conducted and concluded. 

Not to be thwarted, the team working on COBE persevered, looking for other solutions. European and Russian launch vehicles were available but NASA was adamant that such a significant mission would only be flown onboard an American rocket so solutions were very limited. As an almost last ditch attempt, the COBE team approached McDonnell – Douglas. They had some Delta rockets that were planned to be used as targets for President Reegan’s “Star Wars” initiative but to use these Delta rockets, the satellite would require a redesign. The COBE team raced to execute this work as a launch window was fast approaching in 1989. Failure to launch at this time would have resulted in severe delays. 

Stamp from the United States honouring its long and successful history
in launching satellites into space.

As a testimony to the dedication and determination of the COBE team, the satellite was successfully redesigned and launched (with a spare Delta rocket) on schedule. About fifteen minutes after launch, COBE was already in a polar orbit with all systems functioning near flawlessly. Initial coarse sweeps of the sky showed no variation in the CMBR measurements but slowly and surely, over a two-year survey period, which entailed thorough mapping using more than 70 million data points, some of the most important scientific measurements ever recorded started delivering a picture of our early Universe. 

On the 23rd of April, 1992, in a standard twelve minute presentation at a conference of the American Physical Society, the results of the survey were announced. The results were a closely guarded secret and even the organizers of the conference were unaware of the significance of what would be disclosed but in the end, the message was simple: George Smoot and his COBE team had secured evidence that roughly 300,000 years after the Big Bang, there were tiny density variations across the Universe, as it was then. In time, these density variations grew, and ultimately manifest themselves as the galaxies that we observe today. 

In the words of the Newsweek magazine that appeared the following week, the “Handwriting of God” showing the future plan of the Almighty for our Universe, had been discovered.

Recombination 

As previously mentioned, immediately after the Big Bang, the Universe was hot and dense with matter distributed as a highly ionised plasma (the cosmic soup). As the Universe expanded, its density saw a decrease and its temperature also correspondingly reduced. When the Universe was about 370,000 years old, conditions were such that ions and electrons could “recombine” in a process referred to as “recombination”. This period is referred to as the “epoch of recombination”. 

This was the epoch during which elementary particles joined up to form atoms and specifically, charged electrons and protons bonded to form the more complex molecular structure of hydrogen. With protons and electrons now bound together, photons were free to travel unimpeded, causing the Universe to lose its opacity and became transparent. But there was only one light present in those days: the crackle of energy from the Big Bang, the CMBR, which was already ancient but only then allowed to travel for the first time. It is recombination that resulted in the CMBR breaking free of the hot, dense cosmic soup that previously prevailed. 

Many billions of years later, it would be the CMBR that would allow humankind to better understand the creation and evolution of the Universe in which we occupy the small blue dot called Earth. 

At recombination, the Universe had only just managed to evolve such that atoms and then molecules were being formed. Shining stars were still eons away. Apart from the presence of radiation, there was no light and the heavens were still a dark place.

Birth of the First Stars 

The key to stars being born is having an environment that is initially well supplied with cold gas. At recombination, the Universe was still hot with a temperature of approximately 3000 degrees Kelvin but over the subsequent period of time, estimated to be between 150 and 500 million years, atoms present in our young, expanding Universe cooled down further. At this stage, our Universe became more orderly and comprised molecular gas clouds primarily consisting of neutral hydrogen (75% by mass) and helium (25 % by mass) floating in an omnipresent sea of background radiation, the CMBR, a fossil of the Big Bang. There were also traces of lithium and beryllium. Most importantly, clumping, previously discussed, is taking place in a Universe that is slowing thus demonstrating increasing levels of heterogeneity. (A note to the Chemists amongst my readers: At this stage of the evolution of the Universe, only elements one through to four of the Periodic Table existed.) 

The stamp from the United States shows the Eagle Nebula and one of the stellar
nurseries within it called the "Pillars of Creation"

Over time, gravity gradually acts on the densest regions of this pristine gas and gathers it into compact clouds. More and more gas accumulates, being drawn into these compact clouds by an ever-increasing gravitational force. Eventually, this gaseous matter entirely collapses in on itself and the material at the very center of the cloud compresses by the in-falling material on the outside, pushing down to get to the core. At this stage, our soon-to-be-star is called a protostar. The continuous compression heats up the core of the collapsing cloud. The forces are extremely strong and the temperatures, inordinately high, in the region of about 15 million degrees Kelvin.

The countdown has begun and there is no turning back. A nuclear explosion triggers, and a hot, bright star is born! 

This is the moment of creation of the first star in our infant Universe.  This was the moment when the long night of the Universe came an end. From this moment, stars could start delivering heat and light to their surrounding interstellar partners. 

When fusion kicked in, the star began to blast a stellar wind. This wind helped clear out some of the gas and dust clouds around the star. Some dust remained and it is this dust that eventually accumulated to become the planets which orbits a star. For planets that would form in the "Goldilocks zone" or the habitable zone around stars, these were the moments that promised the potential of life. 

All over the Universe around this time, other stars are being born through the same nuclear, stellar ignition process around areas where earlier, higher densities of matter prevailed and accumulated. One by one these primordial stars light up our Universe. The first stars existed before the formation of the first galaxies. These primordial objects – known as population III stars – were made up almost entirely of hydrogen and helium. The life of each of these stars was dependent on its initial mass (very large, massive stars burn their fuel much faster than smaller stars and may only last a few hundred thousand years whilst smaller stars, will last for several billion years, because they burn their fuel at a much slower rate). 

Scientists believe that the first stars were large with conservative estimates placing them at about thirty times the mass of our Sun. It is more likely, that they were about 300 times the mass of our Sun with the most extreme estimates rising up to about 1,000 solar masses. Thus, our Universe was home to enormous stars, which burned through their near - pure hydrogen fuel quickly, perhaps even in only a few million years. 

Evolution of the Second Generation of Stars in the Universe

As mentioned in the preceding paragraphs, when Population III stars run out of fuel (I use the present tense because there appear to still be some out there), their ultimate fate is determined by their size. During their death throes and at their eventual death (when these large primordial stars exploded), they unleashed a slew of heavy elements into the cosmos, polluting it and changing the composition of our Universe forever. These massive stars and the black holes they created on their demise, attracted more stars around them, and the first galaxies began to emerge. Within the galaxies, ejected metals, in the form of dust found their way into the dense concentrations of interstellar gas and dust known as molecular clouds, the largest of which are called “giant molecular clouds”. Within these molecular clouds, a second generation of star formation took place (Population II and Population I stars) in the cold nebulae of stellar nurseries. Stars of all sizes were born and the Universe as we know it now finally began to appear. 

In the diagram below, the Stellar Nebula (on the extreme left of the page) is part of a Molecular Cloud.

Credit: NASA

As an aside to our story on evolution, the concept of categorizing stars into Populations” was first proposed by Walter Baade, a German astronomer, in 1944. Stars observed in galaxies were originally divided into two populations. Population I stars are metal-rich and Population II stars are metal – poor in composition. In the Steady-state model of the Universe, this type of categorization for stars was viable but as the Big Bang model describing the creation of the Universe became accepted, this binary system of categorization was found to be coarse and inadequate as even the most metal-poor Population II stars have metallicities far above that of the gas left over from the Big Bang. 

For this reason, astronomers introduced a third class of star; population III stars which are composed entirely of primordial gas – hydrogen, helium and very small amounts of lithium and beryllium. This means that the gas from which Population III stars formed had not been ‘recycled’ (incorporated into, and then expelled) from previous generations of stars, but was pristine material left over from the Big Bang. Despite intense searches only one report of a Population III star has been published (in 2015). Several plausible reasons have been forwarded to explain why these “pop III” stars have been reclusive and why such a difficulty prevails to discover such stars, but until at least a few more are credibly observed, Population III stars will remain hypothetical in the minds of most astronomers. 

If Population III stars have not been discovered, why do they remain important? The analogy would be to think of the problem faced by of John Chapman (more popularly known as Johnny Appleseed) who is credited with introducing apple trees to many of the states of the United States in the eighteenth century. Johnny Appleseed required seeds (or cores of apples) to grow these new apple trees (that he wished to plant) in the relevant states. As more and more trees were grown and the efforts of Johnny Appleseed literally bore fruit (!), we can conclude that at least some apple trees must have already existed in the United States before the later efforts of Johnny Appleseed. 

This is a series of stamps from the United Kingdom. It shows some large structures found in our Universe like galaxies and nebulae. Note the text on the left of the stamps: "All matter, all energy, is nature and all nature begins with stars. We are star stuff ..."

In the same way, to have the Population II and Population I stars that we can readily observe today, we need also to have or had Population III stars that we (as of now) cannot readily find. It is likely that if Population III stars, did not or do not exist, then the seeds of all the stars in the heavens at all today would not have been sown.

Our Sun 

Before ending this post on stars, I thought I would provide some information on the star of our Solar System, our Sun. 

Our Sun is a yellow dwarf star, a hot spherical ball of glowing gases at the heart of our solar system. It came into being about 4.5 billion years ago. Like all stars, it originated from a massive concentration of interstellar gas and dust which created a molecular cloud that would form the Sun's birthplace in the Milky Way Galaxy. It is estimated that there are between 100 billion and 400 billion stars in the Milky Way Galaxy. Our Sun is not particularly large, having a diameter of about 1.3 million kilometres. Its nearest stellar neighbour is the Alpha Centauri triple star system: Proxima Centauri is 4.24 light years away, and Alpha Centauri A and B—two stars orbiting each other—are 4.37 light years away. 

Part of a First Day Cover from the United States showing one of the many probes that
have been launched into space to understand the Sun.

Astronomers estimate that our Sun has burnt up about half of the hydrogen in its core. This leaves the Sun's life expectancy at about 5 billion more years, at which time, the Sun's elements will "swell" up, swallow the rocky planets, including Earth, and eventually die-off into a small white dwarf. 

An Eclipse of Black Rights 

Today is the 21st of June. In Malaysia, from where I write this post, it is “Father’s Day”. There is also a Solar Eclipse about to occur in the next few hours. I have received several messages from friends in India and other places that this is not an auspicious time to be leaving my home for any outdoor activities. So, I thought I would write my concluding thoughts at this time. 

Part of a First day Cover from the United States celebrating a Total Eclipse of the Sun. Today, on the 21st of June, 2020 there was another such event.

George Floyd was not famous. He was both a dad and a husband, killed on a street corner of Minneapolis in the United States by police officer in a ten-minute act of cruelty, caught on a video that was made viral through the infrastructure of social media. The nature and circumstances of the crime have awoken the emotions of the world against racism and discrimination. They have also inspired protests internationally. Even professional sportsman, resuming their football craft in the English Premier League after a long layoff due to a global medical pandemic, discarded their names from being displayed on the back of their club jerseys and instead carried the words “Black Lives Matter”. 

A stamp honouring America's Black Heritage - Black Lives Matter 

Before the start of every match played this past weekend, each player knelt on one knee, in a gesture of powerful solidarity, in memory of a moment when a man needlessly lost his life, only because of the colour of his skin. Whilst the catalyst of the many demonstrations which have taken place was driven by what happened in America, in each country, varied problems with roots associated to unjust discrimination and deprivation, have added to the motivation that have brought people to the streets. As a result of what happened to George Floyd, his six-year old daughter, Gianna Floyd, will not have a dad with whom to share Father’s Day. 

But why do I bring this matter up? 

Barbra Streisand: A Superstar

It is now time, in this post, to report about another type of star. This is about a star who achieves superstar status. 

Barbra Streisand shares one thing with Gianna Floyd. Both lost their fathers at a very young age in tragic circumstances.  Her father was a high school teacher. Wikipedia reports that in August 1943, after Streisand’s first birthday, her father passed away at the age of 34 from complications from an epileptic seizure, possibly from a head injury, suffered many years earlier. Her family fell into near poverty. 

Wikipedia also reports that as an adult, Streisand recalled those early days “as always feeling like an outcast” explaining, “everybody’s else’s father came home from work at the end of the day. Mine didn’t.” 

Stamps from the island of St. Vincent and the Grenadines located in the Caribbean.
This stamp honours Barbra Streisand - a Superstar 

Thus, it was no surprise for me to read in the paper last week that Gianna Floyd, the daughter of the slain George Floyd, had received a rather unique gift from one Barbra Streisand. Here is an excerpt of the report that I read:

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June 15, 2020, 9:22 PM +08 / Source: TODAY

By Lindsay Lowe

Barbra Streisand gave a special gift to George Floyd’s 6-year-old daughter, Gianna Floyd.

Streisand helped Gianna become a shareholder in Disney, sending her an envelope of what appears to be a Disney stock certificate and a signed letter from the legendary singer herself.

The package also included two of Streisand’s albums, “Color Me Barbra” and “My Name Is Barbra.”

Gianna revealed the gift in a series of photos on her Instagram page, which her family started in the wake of her father’s death.

“Thank You @barbrastreisand for my package,” the caption reads. “I am now a Disney Stockholder thanks to you 🥰🥰🥰.”

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On that note, I would like to sign-off for this week. I hope you have enjoyed this post about the story of the stars and a superstar of our Universe.

Barbra Streisand has a star with her name on a pavement on the North Side of 6900 Block of Hollywood Boulevard. George Floyd has a tombstone (without a star) that bears his name. Our world may turn out to be a better place thanks to this man’s legacy.  In many ways, he too was a superstar! 

Perhaps, just perhaps, someone from the International Astronomical Union who might be reading this post, would consider naming a star, currently shining brightly up there in our night sky, after this man! 

I hope so anyway.

End of Post 

Additional Technical Notes on Stars:

There are many different types of stars, ranging from tiny brown dwarfs to red and blue supergiants. There are even more bizarre kinds of stars, like neutron stars and Wolf-Rayet stars. For those who wish to know more: 

Protostar:

A protostar is what exists before a star forms. A protostar is an accumulation of gas that has collapsed down from a giant molecular cloud. The protostar phase of stellar evolution lasts about 100,000 years. Over time, gravity and pressure increase, forcing the protostar to collapse down. All of the energy released by the protostar comes only from the heating caused by the gravitational energy – nuclear fusion reactions has not commenced at this stage.

T Tauri Star:

A T Tauri star is stage in a star’s formation and evolution right before it becomes a main sequence star. This phase occurs at the end of the protostar phase, when the gravitational pressure holding the star together is the source of all its energy. T Tauri stars do not have enough pressure and temperature at their cores to generate nuclear fusion, but they do resemble main sequence stars; they are about the same temperature but brighter because they are larger. T Tauri stars can have large areas of sunspot coverage, and have intense X-ray flares and extremely powerful stellar winds. Stars will remain in the T Tauri stage for about 100 million years.

Main Sequence Star:

The majority of all stars in our galaxy, and even the Universe, are main sequence stars. Our Sun is a main sequence star, and so are our nearest neighbors, Sirius and Alpha Centauri A. Main sequence stars can vary in size, mass and brightness, but they all perform the same activity i.e convert hydrogen into helium in their cores, releasing a tremendous amount of energy. A star in the main sequence is in a state of hydrostatic equilibrium. Gravity is pulling the star inward, and the light pressure from all the fusion reactions in the star are pushing outward. The inward and outward forces balance one another out, and the star maintains a spherical shape. Stars in the main sequence will have a size that depends on their mass, which defines the amount of gravity pulling them inward

Red Giant Star:

When a star has consumed its stock of hydrogen in its core, fusion stops and the star no longer generates an outward pressure to counteract the inward pressure pulling it together. A shell of hydrogen around the core ignites continuing the life of the star, but causes it to increase in size dramatically. The aging star has become a red giant star, and can be 100 times larger than it was in its main sequence phase. When this hydrogen fuel is used up, further shells of helium and even heavier elements can be consumed in fusion reactions. The red giant phase of a star’s life will only last a few hundred million years before it runs out of fuel completely and becomes a white dwarf.

White Dwarf Star:

When a star has completely run out of hydrogen fuel in its core and it lacks the mass to force higher elements into fusion reaction, it becomes a white dwarf star. The outward light pressure from the fusion reaction stops and the star collapses inward under its own gravity. A white dwarf shines because it was a hot star once, but there’s no fusion reactions happening any more. A white dwarf will just cool down until it becomes the background temperature of the Universe. This process will take hundreds of billions of years, so no white dwarfs have actually cooled down that far yet.

Red Dwarf Star:

Red dwarf stars are the most common kind of stars in the Universe. These are main sequence stars but they have such low mass that they’re much cooler than stars like our Sun. They have another advantage. Red dwarf stars are able to keep the hydrogen fuel mixing into their core, and so they can conserve their fuel for much longer than other stars. Astronomers estimate that some red dwarf stars will burn for up to 10 trillion years. The smallest red dwarfs are 0.075 times the mass of the Sun, and they can have a mass of up to half of the Sun.

Neutron Stars:

If a star has between 1.35 and 2.1 times the mass of the Sun, it does not form a white dwarf when it dies. Instead, the star dies in a catastrophic supernova explosion, and the remaining core becomes a neutron star. As its name implies, a neutron star is an exotic type of star that is composed entirely of neutrons. This is because the intense gravity of the neutron star crushes protons and electrons together to form neutrons. If stars are even more massive, they will become black holes instead of neutron stars after the supernova goes off.

Supergiant Stars:

The largest stars in the Universe are supergiant stars. These are monsters with dozens of times the mass of the Sun. Unlike a relatively stable star like the Sun, supergiants are consuming hydrogen fuel at an enormous rate and will consume all the fuel in their cores within just a few million years. Supergiant stars live fast and die young, detonating as supernovae; completely disintegrating themselves in the process.

Twinkling Stars:

Light from a star is generally constant. It is turbulence of the air in the atmosphere of Earth that sometimes provides a viewer on Earth with the perception that the star is "twinkling".

Note: All stamps  and first day covers displayed in the above post are from my personal collection.