Professor Questions Essay

1. Discourse how uranologists compare the stars.

There may be several footings astronomists use to compare stars. including brightness. flux. energy flux. evident magnitude and absolute magnitude.

Luminosity is the entire sum of energy given from a organic structure every 2nd. measured in Watts

Energy flux is the flow of energy out from a peculiar surface country and is measured in Watts per metre square.

Observed flux – As the radius of the circle placed around the radiating object additions. the flow of energy per metre square would diminish. The ascertained flux would be higher if the radius of the circle is less ( reverse square jurisprudence )

Apparent Magnitude is the sum of visible radiation that is received from a peculiar star. It is determined utilizing the brightness of the star and the distance from us. The evident magnitude would be low for a brighter object.

Absolute magnitude is the sum of visible radiation that is received from a peculiar object when the object is placed at a distance of 10 par secs ( A & A ; B’s Astronomy Lab. University of Columbia. 2002 ) .

2. From nebulae. stars are formed. Discourse the factors that affect the gestation clip for the birth of protostars.

The nebulae from which clouds signifier are nil but clouds of dust and gas. They easy begin to contract to get down the procedure of star formation. The mass is known as the ‘protostars’ and it would go on to distill and easy heat up. Once it reaches a critical mass stage. the atomic merger reaction takes topographic point H atoms fuse together to organize He. two protons and enormous sums of energy. Once this stage begins. the star is born.

Factors that affect gestation clip for the birth of protostars

• Gravity of the passing star ( external energy to assist star formation )
• Shockwave from a nearby supernova ( external energy to assist star formation )
• Heating by contraction ( Giant molecular clouds need to contract to heat up and get down the thermonuclear procedures )
• Magnetic Fieldss available ( helps in contraction )
• Rotation or angular impulse of the protostars
• Size of the star ( smaller stars live longer than larger stars as they take longer to fire their fuel ) ( Sea & A ; Sky. 2008. & A ; UNT. 2008 )




3. Discuss how a stars life affected by its `fuel` ?

Once the protostar gets heated up. atomic merger reaction begins ( thermonuclear procedures ) . and the star now enters its stable stage. The star would be battling gravitative prostration by blending atoms together and organizing energy. The star’s life span depends on how much of affair it really contains. The procedure of atomic merger in the stars would affect transition of H to He. He to C. until Fe is formed. Once Fe is formed. the energy required to blend Fe is much higher and therefore the reaction stops. Larger stars tend to utilize up larger sums of fuel compared to smaller stars. and therefore would populate much shorter.

Several big stars in the universe live for about a few 100s of 1000s of old ages. As smaller stars would be passing their fuel much more easy. they would populate for one million millions of old ages. Once a star’s fuel gets exhausted. it would transform into a ruddy supergiant ( spread outing in size ) . and would be present for sometime. The star would so fall in. as the force of the atomic reactions is non effectual to battle the force of gravitation. Some of the stars blow off. to organize planetal nebulae. The nucleus of the star would incorporate some sum of fuel which would fire as white midget. Once they completely burn off. they would stay as a dark ball known as a ‘black dwarf’ . Some monolithic stars may trip a violent detonation. known as ‘supernova’ ( Airty Nothing. 2008 & A ; Sea & A ; Sky. 2008 ) .

4. Discuss basic thoughts of the chief sequence chart ( Hertzsprung-Russell ( HR ) Diagram ) .

The HR diagram is fundamentally a graph in which the brightness of the stars ( absolute magnitude ) is charted against the surface temperature ( colour ) . This chart was discovered individually by Ejnar Hertzsprung and Henry Norris Russell in the 1910’s. This was following several scientists query whether the temperature of the object could be determined from the colour of radiation it emitted.

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