Members of the STELLAR fam....

Night sky observation was one of the most fascinating events for a space lover...we see plenty of stellars in our night sky while observing from our naked eye...But if use a telescope for our observation we can see more enchanting events...

      

Modern astronomy and astrophysics history goes around 400-500 years and during that time scientist have been discovered over millions of stars through telescopes....but unfortunately we can only visible around 4000 stars from our naked eye due to light pollution...

So because of this vast discoveries of stars scientist wanted to categories them into groups by using its characteristics....So as a result of that "hertzsprung - russel diagram" was created by the scientists named  Ejnar hertzsprung and henry russel in the 20th century....

 The H-R diagram ( hertzsprung - russel diagram ) provides valuable info about stellar evolution....By studying the position of a star in the diagram scientist were able to determine its evolution and characteristics....

( HR diagram )

The X axis represent the surface temperature of the star...and the Y axis represent the luminosity or absolutely magnitude.... By placing on the diagram scientist were able to categorize based on their evolutionary stage , size , temperature and other properties....

The diagram consists of a main diagonal patter named as the main sequence which consists majority of the stars...And the main sequence extends from the upper left which consist of massive and hot stars ( Blue), to the lower right which contains smaller and cold stars....

Other prominent features such as giants , super giants and  white drafs will be clarified later in this article....

Main sequence.....

Main sequence stars can be sub categories to seven types....Named as 

" O class , B class , A class , F class , G class , K class and M class.....

                      ( classes of stars )

Main sequence stars have been divided to seven classes according to its temperature and magnitude...lets find out about each class now.....

Class - O

Class O contains biggest stars in the main sequence...Due to its vast magnitude the life time of a O class type star was about 10-100 million years... These types of stars contain a mass around 16 solar masses.....And have a temperature around 30000k......Due its extreme temperature these types of stars can visible in blue colour....The abundance of these type of stars in the universe goes around 0.00003%......

            ( S - Monocerotis...O class star)

Class - B

Class B stars contain mass around 2.00-16.00 solar masses...And these types of stars have a temperature around 10000k - 30000k.....due to its temperature these types of star can be visible in white blue...And abundance of these types of stars are around 0.13%.....

                ( Rigel - Class  B star )

Class - A

A class type stars have a mass around 1.4-2.1 solar masses...and contains a temperature around 7500k - 10000k.....

These types of stars can be vision in white colour....Abundance of Class -A stars was about 0.65%.....

 (Sirius- Brightest star in the night sky)

Class - F

F class stars have a temperature around 6000k - 7500 k.. And contain a mass around  1.03-1.4 solar mass...These types of stars can be visible in yellow white....3% of the stars were part  of class F......

            ( Procyon - Class F star )

Class - G

G type stars were so special to us because our sun belongs to this class....usually these types of stars lives around 10 billion years and ends their life as a  white dwarf....G class stars have a temperature around 5200k - 6000k.....Around 8% stars in the main sequence were class G....

              ( Alpha centauri A - Class G )

Class - K

K type stars have a mass around 0.45- 0.8 solar mass...And contain a temperature around 3700k - 5000k.....Due its low temperature class k stars can visible in orange colour...These type of stars live around 40-100 billion years.....12% of the stars belongs to class K......Alpha centauri B was a great example for class K stars....

Class - M

M type stars named as red dwarf stars....Majority of the stars in the main sequence were red dwarfs ( 77%)... These stars lives more than trillion years due to its low magnitude ... M class stars contains a temperature around 2400k -3700k.....And have a mass around 0.08- 0.45 solar mass....These types of stars often inflict solar flares....I will write a separate article about red  dwarfs in near future..  

       ( proxima centauri - red dwarf )

 A star consist a nuclear reaction to produce heat....For that , A star must contain a minimum mass around 0.08 solar masses...But some stars doesn't contain that mass and these types of stars named as brown dwarfs....It also named as " Failed stars "......

Now lets talk about supergiants and giants....

In my previous articles I've given vast clarification about these two types of stars..  Usually supergiants ends their life with a supernova and becomes a blackhole or a neutron star.....And red giant stars will become white dwarfs....

If you were interest in astronomy , astrophysics... I request you to stay in touch with space exploration......

                                               Thank you

                                            🖊️ shehan

                     ( undergraduate in physics)