# What factors affect the luminosity of a star?

There are some specific factors that affect luminosity. 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.

In this manner, what is the relationship between temperature and luminosity of the main sequence stars?

Volume must be taken into consideration as well. But the relationship between mass and a main sequence star’s luminosity is far more straightforward. A main-sequence star is a star lying on the main-sequence band of the H-R diagram, and an H-R diagram is a diagram that plots a star’s luminosity vs. surface temperature.

What is the difference between a star’s brightness and luminosity?

When I say apparent brightness, I mean how bright the star appears to a detector here on Earth. 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.

## 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.

## How is luminosity 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 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 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.

## 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 is the color of the stars from hottest to coldest?

In general, a star’s temperature determines its color, from red to blue-white. Spectral types are named with a letter: M, K, G, F, A, B and O. M stars are the coldest stars and O stars are the hottest. The closest star to the Earth, the sun, is a class G star.

## 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 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.

## What are the units of luminosity?

Luminosity. In astronomy, luminosity is the total amount of energy emitted per unit time by a star, galaxy, or other astronomical object. As a term for energy emitted per unit time, luminosity is synonymous with power. In SI units luminosity is measured in joules per second or watts.

## 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.

## 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.

## How does the star’s color change as its temperature increases?

Stars emit colors of many different wavelengths, but the wavelength of light where a star’s emission is concentrated is related to the star’s temperature – the hotter the star, the more blue it is; the cooler the star, the more red it is.

## 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.

## 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.

## 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).

## Why do some stars shine brighter than others?

A star’s brightness also depends on its proximity to us. The more distant an object is, the dimmer it appears. Therefore, if two stars have the same level of brightness, but one is farther away, the closer star will appear brighter than the more distant star – even though they are equally bright!

## Why are stars different colors?

As the light from the stars comes through the earth’s atmosphere, they appear to be twinkling. This makes the cooler stars appear red and the stars with the higher temperatures appear blue or white. From cool to hot, the colors can appear red, orange, yellow, green and blue.

## 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.

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