# What factors determine the luminosity of a star?

As the size of a star increases, luminosity increases. If you think about it, a larger star has more surface area. That increased surface area allows more light and energy to be given off. Temperature also affects a star’s luminosity.

Besides, how is the luminosity of a star measured?

To do so, astronomers calculate the brightness of stars as they would appear if it were 32.6 light-years, or 10 parsecs from Earth. Another measure of brightness is luminosity, which is the power of a star — the amount of energy (light) that a star emits from its surface.

What are the factors that determine the brightness of a star?

Two factors determine the brightness of a star:

• luminosity – how much energy it puts out in a given time.
• distance – how far it is from us.
• What does the luminosity of a star depends on?

The Luminosity of a star depends on BOTH its temperature and its radius (surface area): L is proportional to R2 T4. A hotter star is more luminous than a cooler one of the same radius. A bigger star is more luminous than a smaller one of the same temperature.

## What determines the temperature luminosity and diameter of a star?

This leaves a small, hot core about the size of the Earth—a white dwarf. MASS governs a star’s temperature, luminosity and diameter. At the core of a main sequence star, hydrogen atoms are fused into helium atoms (nuclear fusion), releasing incredible energy (E=mc^2).

## Why is measuring the luminosity of a star difficult?

The distance of stars relative to earth makes it difficult to measure brightness since a bright star that is more distant might appear to be as bright as a more dim star closer to earth. Sketch and label the HR Diagram. The class of star that corresponds to the color we observe from earth.

## Why do supergiants have a high luminosity?

Stars more massive than the Sun not only burn out more quickly, but they burn much hotter and brighter. Less massive stars burn cooler and dimmer. Temperature translates to color, and this relationship between color and brightness (luminosity) for hydrogen-burning stars is called the main sequence.

## Is luminosity the same as brightness?

The luminosity of a star, on the other hand, is the amount of light it emits from its surface. The difference between luminosity and apparent brightness depends on distance. So, everyone will measure a different apparent brightness for the same star if they are all different distances away from that star.

## What determines the temperature of a star?

The temperature of a star’s photosphere can also be deduced from its color. Cool stars (such as Betelgeuse, which has a surface temperature of T = 3500 Kelvin) emit more red and orange light than blue and violet light.

## Is there a relationship between the mass and luminosity for stars on the main sequence?

Observations of thousands of main sequence stars show that there is definite relationship between their mass and their luminosity. The more massive main sequence stars are hotter and more luminous than the low-mass main sequence stars.

## What are the factors that affects the color of the stars?

The color of a star is mainly decided by the surface temperature of the star but other factors also affect color of the star. Human eye is more sensitive to blue light than red in the night which gives bluish appearance to the stars.

## What is the main sequence phase of a star?

Definition of a Main Sequence Star. A main sequence star is any star that is fusing hydrogen in its core and has a stable balance of outward pressure from core nuclear fusion and gravitational forces pushing inward.

## What outward force balances against gravity in a star like our sun?

Energy is generated in the star’s hot core, then carried outward to the cooler surface. Inside a star, the inward force of gravity is balanced by the outward force of pressure. The star is stabilized (i.e., nuclear reactions are kept under control) by a pressure-temperature thermostat.

## What determines the color of the stars?

The upshot is this: the color of a star depends on its surface temperature. But a blue star doesn’t emit only blue light, nor does a red star emit only red light. They emit visible light of all colors to some degree. It’s just that their spectrum peaks at a particular color.

## What is the coolest color of a star?

Since the temperature of a star can determine its visual color, this category scheme is known as spectral type. The main categories of spectral type are M, K, G, F, A, B, and O. The coolest stars (red dwarfs) being M, and the hottest stars being O. Our own Sun is a G star.

## What can you tell from the color of a star?

A star’s color is critical in identifying the star, because it tells us the star’s surface temperature in the black body radiation scale. The sun has a surface temperature of 5,500 K, typical for a yellow star.

## What gives a star its power?

The nuclear reactions inside convert hydrogen into helium by means of a process known as fusion. It is this nuclear reaction that gives a star its energy. Fusion takes place when the nuclei of hydrogen atoms with one proton each fuse together to form helium atoms with two protons.

## How do we know what the stars are made of?

How do astronomers know what stars are made of when those stars are light years away from Earth? File under astronomical spectroscopy: Newton used a prism to split white light into a spectrum of color, and Fraunhofer’s high-quality prisms allowed scientists to see dark lines of an unknown origin.

## Are bright stars hotter?

That is why it is red — red stars are cooler than the sun, blue-white stars are hotter. Betelgeuse is, however, much bigger and brighter. It is about 500 times bigger than our sun. Also it is about 10,000 times brighter than our sun (because a larger star is brighter).

## What is the difference between an asterism and a constellation give an example of each?

A star pattern that is not officially recognized by the international scientific community (International Astronomical Union) as a constellation is called an asterism. The stars that form asterisms can be part of one or more constellations. For example, the Big Dipper is an asterism within the Ursa Major constellation.

## How does the sun compared to other stars in the universe?

How Does Our Sun Compare With Other Stars? Our sun is a bright, hot ball of hydrogen and helium at the center of our solar system. It is 864,000 miles (1,392,000 km) in diameter, which makes it 109 times wider than Earth. There are billions more stars in the Milky Way galaxy – the galaxy we call home.

## Is the surface temperature of white dwarf?

Such stars eventually blow off the material of their outer layers, which creates an expanding shell of gas called a planetary nebula. Within this nebula, the hot core of the star remains—crushed to high density by gravity—as a white dwarf with temperatures over 180,000 degrees Fahrenheit (100,000 degrees Celsius).

## What are the characteristics of giants and supergiants?

Subclasses of giants are supergiants, with even larger radii and brightness for their masses and temperatures (see supergiant star); red giants, which have low temperatures but are of great brightness; and subgiants, which have slightly reduced radii and brightness.

Categories FAQ