The brightness of a star - or apparent magnitude [See related question] is how bright a star is as viewed from Earth.
Therefore, if we have two stars of similar luminosity but one is twice as far away, then the further star would appear dimmer than the closer star.
There are more luminous stars than our Sun but because the Sun is a lot closer, it is brighter.
So the brightness of a star depends on it's luminosity and it's distance from the observer.
A stars luminosity is a factor of how hot it is, and how big it is.
The star's apparent brightness depends on its real (absolute) brightness, and its distance.
The star's real brightness depends on its surface area and temperature - but ultimately, on the amount of energy produced within the star.
A star's apparent magnitude may depend on:
If this question was grammatically correct, it would have read: "What does a star's brightness depend on?" Nevertheless, I will answer it =P A stars brightness depends on who is viewing the star and where they are viewing the star from. Brightness depends on three main aspects: 1. How far the star actually is from the viewer (usually measured in light years, since noone currently inhabits space-that we know of) 2. How old the star is and 3. How bright the star actually is. For example, If a person is in Antarctica, and looking at the north star, the star will be very very bright. Versus : If a person is in Brazil, looking at a star that is further away, for example, a star on the constellation Orion, it will be less bright to the viewer because it is potentially billions of light years away. This same star on Orion could actually be brighter than the North Star because it may be a younger star. Younger stars are naturally brighter than older stars that have been burning for millions of years that may be close to becoming a black hole. I hope this helped!
The apparent brightness of a star depends on its absolute brightness and on its distance, mainly. Sometimes, matter (gas and dust) between us and the star can also affect its apparent brightness.
A star's absolute brightness depends on its diameter and temperature. Ultimately, though, in a stable star it depends on how fast energy is produced in the interior. This is affected by several interrelated factors, including the star's core temperature and pressure, the star's mass, and what percentages of each element make up the star.
1) If you mean the apparent brightness, as seen from Earth, that depends on the star's real luminosity and its distance from Earth.
2) If you mean the star's real luminosity, that depends on its surface temperature and its surface area.
A star's apparent brightness depends on (a) its real brightness, (b) its distance from us, (c) any intervening matter that might affect the light reaching us, such as dust and gas (which will dim the light), or gravitational lenses (which may actually make it seem brighter in some cases).
Two of the things brightness depends on are size and temperature I am not sure of the third, but based on the Presents Hall, "Earth Science" text book page 754 there are only two things that brightness depends on.
-- its real brightness
-- its distance from us
-- any material in the line from the star to us that might partially absorb
and thereby dim the star's light on its way to us
A star's brightness, or "magnitude", depends on its size. The bigger, the brighter.
We divide "magnitude" into two categories; "absolute magnitude" and "apparent magnitude". "Absolute" magnitude is a measure of how bright, how large, the star actually is. "Apparent" magnitude modifies this by accounting for distance; of two stars with the same absolute magnitude, the closer one will have a lower (brighter) apparent magnitude.
The brightest stars were originally called "first magnitude", with dimmer stars being categorized as "second magnitude" and still dimmer stars being third, fourth or fifth magnitude. The dimmest stars visible in a DARK sky in a CLEAR night are seventh magnitude, if your eyes are perfect.
When the mathematicians and engineers got hold of the concept, they added a category of "zero magnitude" stars which are the very brightest, and even negative magnitude stars which are even brighter.
distance from the sun and the age of the star
First let's assume the question is about a star's actual brightness not apparent brightness as seen from Earth. There are in fact several possibilities. The Hertzprung-Russell diagram is helpful here. One possibility is red dwarfs and white dwarfs. Of course there's large variation within these groups, but a red dwarf can certainly have a luminosity that's similar to a white dwarf. If the question is about apparent brightness, then a distant luminous star can appear similar in brightness to a nearby faint star.
Two characteristics that distinguish the star Polaris from the star Aldebaran are their brightness and their positions in the night sky. Brightness: Polaris, also known as the North Star or Pole Star, is relatively bright and is the brightest star in the constellation Ursa Minor. It serves as a reliable navigational reference point due to its brightness and its position near the North Celestial Pole. On the other hand, Aldebaran, which is located in the constellation Taurus, is also a bright star but not as bright as Polaris. Position in the night sky: Polaris is located very close to the North Celestial Pole, which means it appears almost stationary in the night sky as the Earth rotates. This makes it useful for navigation and finding the direction of true north. Aldebaran, on the other hand, is not located near any celestial pole and appears to move across the sky like other stars as the Earth rotates. These two characteristics make Polaris and Aldebaran distinct from each other in terms of brightness and their positions in the night sky.
The Hertzsprung-Russell diagram shows absolute magnitute or brightness against it's colour (which is an indication of temperature) . This shows the main sequence, which describes the typical life of a star.
The surface temperature and the absolute magnitude, which is the brightness of the star when viewed from a standard distance of 10 parsecs.
Two factors that affect a star's apparent brightness are: 1.) The distance between the Earth and the star 2.) The absolute magnitude (the actual brightness) of the star Hope that helps :P
distance from the sun and the age of the star
It's distance from Earth and the star's actual brightness
the watts in the lamp and the volts behind the light
Scientists actually use two measurements to identify a star's brightness. One is luminosity, or the energy that star puts out. Another is magnitude, or the amount of light a star puts out.
brightness and temperature are both related because brightness is actually tempature. However the system has become more refined. Instead of just looking at the star and determining magnitude one or magnitude two, an astronomer measures the brightness of the star using a device called a photometer. The photometer counts the number of photons coming from the star. This photon count is then compared to the photon count from a star whose magnitude is known. An accurate magnitude can then be calculated.
First let's assume the question is about a star's actual brightness not apparent brightness as seen from Earth. There are in fact several possibilities. The Hertzprung-Russell diagram is helpful here. One possibility is red dwarfs and white dwarfs. Of course there's large variation within these groups, but a red dwarf can certainly have a luminosity that's similar to a white dwarf. If the question is about apparent brightness, then a distant luminous star can appear similar in brightness to a nearby faint star.
The H-R diagram graphs total brightness versus surface temperature (related to color); by itself, it doesn't tell you where those two things come from.The brightness of a star depends on its mass, and on where it is in its development history.
For the same real brightness, at a larger distance it would look less bright. On the other hand, you may have two stars that look like they are the same brightness, but one might be million times brighter (in real brightness) than the other - which would be compensated by the fact that the brighter star is a thousand times farther away.
Two stars revolving around one another (around their center of mass, to be precise) are called a "binary star". There is no special name for the case that the brightness is unequal; this is actually the usual case.
there are two separate ways that astronomers measure the brightness of a start, there is actuall and aparent brightness. In apparent brightness, the measure how bright it looks to all the humans on Earth. However, the actual brightness of a star is different. Say a star is really, really bright, but really far away. That star would look preety dim. Or if a star is not so bright, but really close, like the Sun. The actuall brightness of a star is harder to measure, but is possible by use of waves and stuff like that, I don't know too much about actuall brightness
One dimmer star can be closer than a brighter star that is far away. Light flux decreases as the square of the distance. A star that is three times as far away will have to shine nine times brighter than the closer star (absolute magnitude) to appear to have the same magnitude (apparent magnitude). Because apparent magnitude is the brightness of a star, as seen from Earth, whereas absolute magnitude is the brightness of a star as seen from the same distance - about 32.6 light years away.