Fiery Orbs Of The Celestial Domain

Luminous Sphere of plasma is a massive body beholding astonishing mass, the diamonds that adorn the skies, the stars never cease to amaze everyone.

Pleiades, Credits, Wikimedia Commons

The primordial elements: Hydrogen, Helium, and Lithium are from the first Nucleosynthesis. This is a process by which a new element is formed by the result of the combination of Pre-existing nucleons. These elements are then recombined in various processes to make heavier elements, which then clump into structures called globules. These globules then huddle up together along with dust and gas to form Protostar. These primeval stars are composed of about 70% hydrogen and 28% helium and the rest contains heavier elements in its core and the outer surface.

The traces of the elements in the star can be measured by a process called Astro-Spectroscopy which is the analysis of the interaction between matter and any portion of the electromagnetic spectrum. It involves any interaction between light and matter, including absorption, emission, reflection etc. These newly formed stars are called Pre-Main sequence which would then turn into Main sequence stars because for next few billion years it is going to undergo Thermonuclear fusion to sustain its life converting hydrogen into helium. When this period of time ends, there are different ways that the stars end their life.

The Life cycle of stars

Credits, R.N. Bailey

Credits, Wikimedia Commons

Stars are born out of a massive cloud of dust and gases called Nebulae. Then their life is fueled by series of Nuclear fusion reactions. Different types of stars end their lives in different ways.

If the star's mass lesser than 2.5 times the Solar mass, after their period of existence as Main sequence stars, they terminate their fusion and an outer layer of the star collapses and the core turns into a white dwarf. Stars with a mass more than 2.5 M☉ but less than 5 M☉, the helium content in their bodies rises, expand in size to become a red giant, their Helium is then converted to carbon, white slowly emitting out rest of the element out as gases and high energy particles. When the core cannot sustain any more fusion, the tar sheds its outer shell and converts into planetary nebula while the core is converted into a white dwarf. Stars with masses more than 5M☉ but less than 10 M☉ swell up to massive supergiant's and fuse the heavy element to elements with mass higher than Iron. When the core can not sustain any more fusion, these stars collapse into an eminent finale of explosion called the supernova.

Stellar Nucleosynthesis and Core Burning

Onion Peel Model, Credits, Wikimedia Commons

The binding of lighter elements into an element of higher atomic mass in stars results in formation of elements like Lithium, Neon, Silicon, Oxygen, Sulfur, Chlorine, Argon, Manganese, Potassium, Carbon, Calcium, Titanium, Chromium, Nickel, Cobalt, Iron, Magnesium, such elements retain distinctive spectral lines appearing in spectroscopic analysis.

Helium Nucleosynthesis:

The Proton-Proton cycle is a process where two atoms of hydrogen get converted to its Isotope Deuterium, positron, and a neutrino. This binds with another proton to mold into Helium-3 with the release of gamma radiation. Two atoms of He-3 then bond together to form Helium-4 and two protons. This process continues where He-3 and He-4 combine to generate Beryllium and it merges with an electron to create lithium.

Lithium which is mostly present in Brown Dwarfs, whose core and surface temperatures are not high enough for it to carry out hydrogen fusion. These stars rapidly reduced their lithium content by bombarding it with hydrogen to create two atoms of He-4. When Carbon, oxygen, and Nitrogen are generated by Heavy element fusion, they catalyze a 4 proton reaction resulting in the production of Helium-4. In the C-N-O cycle, utilizing carbon, nitrogen and oxygen isotopes as catalysts, 4 protons produce one helium nucleus, two Positrons, and two electron neutrinos. In massive stars whose merging reactions are much faster, and to keep the core intact and to intercept it from collapsing, the Carbon in it takes place in the reactions to produce fusion energy. After this burning of Carbon comes similar acknowledgments of Neon followed by Oxygen and Silicon. Each reaction raises the surface temperature of the host star to favor the next condition, which reaches to astonishing 3.5 Billion Kelvin. Then stars when having triggered the production of elements with a mass greater than iron, the neutron-rich stable isotopes f the element is achieved by capturing of the nucleus by nucleons (S&P-Processes).

Stellar Classification

The Luminosity of the Stars can be measured by,

Apparent magnitude : Luminosity measure of a celestial object as it appears in the night sky of Earth.

Absolute magnitude: The luminosity of object if viewed from a distance of exactly 10 parsecs i.e. 32.6 light years

High numbers represent dim objects and low numbers represent bright ones.

The basic formula relating the apparent (m) , absolute (M) magnitudes and distance to the object (D)

M = m + 5 –( 5 log D)

Atoms and molecules absorb and emits radiation at distinct wavelengths, causing the appearance of spectral lines.

When acquiring a spectrum of an astronomical object spectral lines determine properties like composition, temperature, velocity, Doppler shift etc. There are characteristic lines from many-electron atoms like practically every element.

An opaque hot object, emit continuous unbroken bands of wavelength called Continuous spectrum. If a continuous spectrum is passed through a cool transparent gas, certain wavelengths are absorbed and dark lines appear in spectrum, this is called Absorption spectrum. If this gas is surrounded by opaque background which also emits radiation, its called emission spectrum, which are colored lines in dark background.

Credits, Wikimedia Commons

Harvard Classification ( Hertzsprung–Russell diagram)

Credits, Wikimedia Commons

The stars' absolute magnitudes and its effective temperatures share a relationship, which is given by a scatter plot called the HDR diagram.

The star's brightness against its temperature, is plotted on a graph. Determined by the width of certain absorption lines in the star’s spectrum, which vary with the density of the star’s atmosphere.

0 -- hyper giants or extremely luminous super giants.

Ia – luminous super giants

Iab – intermediate luminous super giants

Ib – less luminous super giants

II – bright giants

III – normal giant stars

IV – sub giants

V -- main-sequence stars

sd prefix – sub dwarf prefix

D prefix – white dwarf prefix

Morgan–Keenan (MK) system

Morgan-Keenan system has letters in which the stars are classified into, O, B, A ,F G, K and M, where M is the coolest and O being hottest. These letters are further divided into numbers that range from 0 to 9, where 0 is hottest and 9 is the coolest.

O star: Strongest line is C III, N III, O III, S IV, He I

B star: Strongest line is He I, H I , Ca II, O II, Si II, Mg II

A star: Strongest line is H I

F star: Strongest line is Ca II, Fe I, Fe II, Cr II, Ti II

G star: Strongest line is Ca II, CN

K star: Strongest line is Ca II

M star: Strongest line is Ca I, TiO

Yellow dwarf- Sun

Wasp 8b, Credits, Wikimedia Commons

These are main sequence stars mistaken to be Yellow in color, in reality are blend of VIBGYOR, that is white. Its surface temperatures ranges between 5000 to 7500 K. These stars at the end of their life will swell up to Red dwarf while producing excessive Helium due to fusion.

Red dwarf- TRAPPIST-1

Credits, NASA.com

These are small and cool stars, very faint magnitude of luminosity and have surface temperatures below 3700 Kelvin. They conserve fuel while burning with less luminosity.

Giants- Red(Mira-A), Blue(Alcyone)

Alcyone, Credits, Wikimedia Commons

A red and blue giant is a stars that are at end of their lives. Most main sequence star with mass lesser than 5 times the Solar mass expands into a Giant. Red Giant has relatively cooler surface temperatures under 6000 Kelvin compared to Blue Giants astonishing 33,000 Kelvin. Asymptotic giant branch (AGB) are evolved cool luminous giants.

Super giant- RV Tauri

Betelgeuse, Credits, Wikimedia Commons

When the stars are of greater Solar mass towards their younger age, they grow into super giant. These have onion like structure core, with each layer rich in an element synthesized by Stellar fusion.

White dwarf- Sirius B

Picture Credits, pixabay.com

Dense and small cores of once Red giants whose outer shell collapsed into Planetary Nebulae.

A white dwarf will cool down until it reaches the background temperature of the Universe to be converted to Iron rich black dwarf. Mass of a white dwarf star cannot exceed 1.4 solar mass according to Chandrasekhar limit.

Brown dwarf- Gliese 229B

Picture Credits, Wikimedia Commons

Lithium rich stars whose surface temperate are not favorable for Thermonuclear fusion. They have very low mass and luminosity.

Neutron Star- PSR B1509-58

Picture Credits, Flickr

When massive star explodes into Supernova, its heavy core is left behind in supernova remnant, spinning at high velocity coupled with the additional momentum from supernova blast emitting high magnitude Magnetic fields giving raise to a Neutron star. If stars posses more mass, they will end up as black holes after the supernova. Rapidly spinning neutron star with high magnitude magnetic field is called Pulsar.

Hyper giant- NML Cygni

Picture Credits, Wikimedia Commons

Class 0 in luminosity, rapidly loosing mass these are stars are the biggest of all types. They are at the end of their time and highly unstable.

Sun is a G type main sequence star. Placing your cameras in Star track mode for 15 minutes to 8 hours would enable you to take Star Trail pictures. The surface temperature of the Sun is about 5800 K. The largest star ever recorder is UY Scuti. HE 1523-0901 and BD +17° 3248 are oldest known stars of about 13.2 billion years of age. Group of stars forming recognizable patterns in the sky are called constellations and there are 88 constellations.

Picture Credits, Wikimedia Commons

Picture Credits, Wikimedia Commons

Andromeda- Princess of Ethiopia

Antlia- Air pump

Apus- Bird of Paradise

Aquarius- Water bearer

Aquila- Eagle

Ara- Altar

Aries- Ram

Auriga- Charioteer

Bootes- Herdsman

Caelum- Graving tool

Camelopardus- Giraffe

Cancer- Crab

Canes Venatici- Hunting dogs

Canis Major- Big dog

Canis Minor- Little dog

Capricornus- Sea goat

Carina- Keel of Argonauts' ship

Cassiopeia- Queen of Ethiopia

Centaurus-Centaur

Cephus- King of Ethiopia

Cetus- Sea monster (whale)

Chamaeleon- Chameleon

Circinus- Compasses

Columba- Dove

Coma Berenices- Berenice's hair

Corona Australis- Southern crown

Corona Borealis - Northern crown

Corvus- Crow

Crater- Cup

Crux- Cross

Cygnus- Swan

Delphinus- Porpoise

Dorado- Swordfish

Draco- Dragon

Equuleus- Little horse

Eridanus-River

Fornax- Furnace

Gemini- Twins

Grus- Crane

Hercules- son of Zeus

Horologium- Clock

Hydra- Sea serpent

Hydrus- Water snake

Indus- Indian

Lacerta- Lizard

Leo- Lion

Leo Minor- Little lion

Lepus- Hare

Libra- Balance

Lupus- Wolf

Lynx- Lynx

Lyra- Lyre

Mensa-Table mountain

Microscopium- Microscope

Monoceros- Unicorn

Musca- Fly

Norma-Carpenter's Level

Octans- Octant

Ophiuchus- Holder of serpent

Orion-Orion- the hunter

Pavo- Peacock

Pegasus- Pegasus, the winged horse

Perseus- Perseus, hero who saved Andromeda

Phoenix- Phoenix

Pictor- Easel

Pisces- Fishes

Piscis Austrinis- Southern fish

Puppis- Stern of the Argonauts' ship

Pyxis - Compass on the Argonauts' ship

Reticulum- Net

Sagitta- Arrow

Sagittarius- Archer

Scorpius- Scorpion

Sculptor- Sculptor's tools

Scutum- Shield

Serpens- Serpent

Sextans- Sextant

Taurus- Bull

Telescopium- Telescope

Triangulum- Triangle

Triangulum Australe- Southern triangle

Tucana- Toucan

Ursa Major-Big bear

Ursa Minor- Little bear

Vela- Sail of the Argonauts' ship

Virgo- Virgin

Volans- Flying fish

Vulpecula- Fox

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