Stars 

Stars are one of the most mesmerising celestial objects in the universe. A star may seem like a little ball of light twinkling in the sky, but they are some of the most massive and heavy objects in the universe. Like our Sun, the closest star to the Earth.

1.0Introduction to Stars 

A star is a shining celestial body primarily composed of hydrogen and helium gas. It undergoes nuclear fusion in its core, releasing energy in the form of light and heat, which makes stars shine in the night sky. Like the Nearest Star to Earth, the Sun. Another example of one such star is Proxima Centauri, The nearest Star to Earth after the Sun. 

Life Cycle of Stars 

It is quite interesting, but stars, too, have their own lifecycle, and they, too, are born and die like everything else in the universe. 

• Nebulae: This is the beginning stage of the stars. Nebulae are the huge mass of clouds of gas and dust. 
• Gravitational Collapse: Under the influence of high gravity, the nebula collapses and forms large clumps that, after some time, heat up and begin nuclear fusion. 
• Protostar: A protostar is the early form of the actual star before the main function of stars begins. 
• Main Sequence Star: Once the nuclear fusion starts in the core of the star, it becomes the fully grown main sequence star. 
• Death of the Star: Every star, when completely used up its fuel, which is hydrogen converted into helium through nuclear fusion, dies, and every star, according to its mass, forms another heavenly body like a black hole or a White Dwarf.

Types of Stars 

Star Types	Figure
Main Sequence Stars These stars are in their stable life cycle, fusing hydrogen into helium in their cores to produce energy. The Sun is a classic example of a main sequence star.
Red Giants When the fuel of hydrogen gets exhausted from the star's core, it starts contracting the inner core and expanding the outer layers. Red giants become cooler and redder, symbolizing a later phase in the evolution of stars.
White Dwarfs Dense, small remnants of low- to medium-mass stars that have exhausted their nuclear fuel. They no longer undergo fusion and gradually cool over time.
Neutron Stars It is formed by the extremely dense remnants of a massive star(s) that has/have undergone a supernova explosion. They are mainly composed of neutrons and possess intense gravitational and magnetic fields.
Red Dwarfs  Small cool stars that burn hydrogen in a slow manner and thus take a long to live. The most common type of stars in the Milky Way Galaxy.
Brown Dwarfs Sub-stellar objects are neither too small to support the fusion of hydrogen-like stars nor large enough to be classified as planets. They emit faintly with residual heat.

2.0Special Stars and Constellations

Procyon Star

Procyon is a binary star system with an apparent distance of 11.46 light-years in the Canis Minor constellation. Procyon A, its primary component, is a main-sequence star with a slightly larger and hotter mass compared to the Sun, reaching near the end of the hydrogen-fusion phase. The secondary star, Procyon B, is a white dwarf, which is a remnant of a low-mass star in an extremely dense form.

Morning Star

The term "Morning Star" is the name for the planet Venus when it shines bright in the early morning sky right before sunrise. It is not a star but often appears as such because of its brightness.

UY Scuti

The largest Star in the Milky Way Galaxy, UY Scuti is a red supergiant in the Milky Way galaxy, and it is the largest star. It has a radius about 1,700 times bigger than that of the Sun, and it is around 9,500 light-years away from Earth.

Regulus Star

Regulus is the brightest star of the Leo constellation and is a blue giant. It is estimated to be 79 lightyears away and is part of a multiple-star system. It is also known to complete one full rotation in merely 16 hours.

Ursa Major

The Most famous constellation of the night sky for direction navigation is Ursa Major also known as the Great Bear or the Big Dipper. It is a prominent constellation both in the Northern and the summer months. It consists of seven stars including the Polaris star (Dhruv Tara) gaining its name of Saptrishi. It makes a plough-like formation. 

Orion Constellation

Orion is another striking and famous constellation in the night sky visible in both the Northern and Southern hemispheres in the late evenings of winter months (summer in the southern hemisphere). Orion is also used for navigation purposes although not as the prime navigator, for locating other important stars like Sirius. In ancient Greek mythology, Orion was known to be a great hunter who was placed among stars after his death. 

Ursa Minor

Ursa Minor, or the Little Bear, is an important constellation in the Northern Hemisphere for playing a central role in navigation. It forms the same formation as of Ursa Major but bit dimmer than that of Ursa Major. The presence of Polaris, the North Star, or the Dhruv Tara, has made it an important reference for travelers.

Sirius Star

Sirius, also known as the Dog Star, is the brightest star in the night sky and one of the most famous stars all over the world. It is part of Constellation Canis Major (the Greater Dog), gaining its nickname of Dog Star. 

3.0Physics Behind Twinkling of Stars 

Stars twinkle due to the light passing through the layers of the Earth's atmosphere. During the passage, it encounters the difference in temperatures, pressures, and densities, whereupon the light bends through or refracts in varied directions. This constant bending in all directions makes the brightness appear different and creates twinkling. For that reason, stars twinkle since they are thousands of light-years away, thereby showing up as point sources of light. In contrast, planets do not twinkle much as they appear closer and resemble discs.

4.0Also Read