If the distance between us and a star is doubled with everything else remaining the same the luminosity?
remains the same, but the apparent brightness is decreased by a factor of four
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In astronomy, Luminosity is the amount of energy a body radiates per unit time.. The luminosity of stars is measured in two forms: apparent (counting visible light only) and bolometric (total radiant energy); a bolometer is an instrument that measures radiant energy over a wide band by absorption a…nd measurement of heating. When not qualified, luminosity means bolometric luminosity, which is measured in the SI units watts, or in terms of solar luminosities, ; that is, how many times as much energy the object radiates than the Sun, whose luminosity is 3.846Ã10 26 W.. Luminosity is an intrinsic constant independent of distance, and is measured as absolute magnitude corresponding to apparent luminosity, or bolometric magnitude corresponding to bolometric luminosity. In contrast, apparent brightness is related to distance by an inverse square law. Visible brightness is usually measured by apparent magnitude, which is on a logarithmic scale.. In measuring star brightnesses, visible luminosity (not total luminosity at all wave lengths), apparent magnitude (visible brightness), and distance are interrelated parameters. If you know two, you can determine the third. Since the sun's luminosity is the standard, comparing these parameters with the sun's apparent magnitude and distance is the easiest way to remember how to convert between them. (MORE)
A thorough answer would take a long time. I'll try to give a simplified answer. There's more than one way these distances are measured or estimated. The distance to most stars is estimated, not measured. As stars are further away, distance is measured using different methods. This use of diffe…rent methods as the distance increases is called the "cosmic distance ladder." Method 1: The distance to close stars is measured using trigonometry -- a method called triangulation. This is difficult to explain without pictures. The angular location of the star in the sky is measured. Then six months later, when the earth is on the opposite side of the sun, it's measured again. The difference in these two angles is used to calculate the distance. This only works for nearby stars. Method 2: For intermediate distances a method based on brightness is used. Certain stars brightness pulsates -- they get brighter and dimmer in a rhythmic manner. The maximum brightness of these stars can be calculated based the rate at which they get brighter and dimmer -- the rate their brightness pulsates. Stars get dimmer the further they are away, so by calculating how bright they really are using the above method and then measuring how bright they appear to us, the distance to them can be estimated. The method cannot be used for distant stars. This method is less accurate than method 1 and more accurate than method 3. Method 3: For very distant stars they use a method called "red shift" to estimate their distance. It's believed the universe is expanding and the further away stars are the faster they're moving away from us. As a star moves away from us the color of the light from it changes -- becomes redder and redder the faster it's moving away. By measuring the color of the light from a star they know how fast it is moving away. Then they make calculations about how distant an object is that's moving away that fast. (MORE)
What is the length of a piece of string? No-one can know for sure, because there are assumed to be a ridiculously big number of stars in the universe. Proxima Centauri, our nearest star other than the sun, is 4.2 LY away. Sirius A and B are 8.6 LY away You could also look at the related q…uestion below. (MORE)
No. There can be huge differences. A brighter star at a bigger distance will look just like a weaker star at a shorter distance.
Distance between stars are usually expressed in terms of light years, the distance that light (a form of electromagnetic radiation) travels in the period of one year. The unit 'parsec' (abbreviated pc) is about 3.26 light years.
It is how bright a star is, but it depends on which star your talking about
No, the distance does change a bit. The Earth's orbit is almost a circle, but it's actually an ellipse.
Laypeople tend to use light years. Astronomers generally use parsecs, which has the advantage of sounding (slightly) less like a time unit than "light years" does (though not a lot less; Han Solo in Star Wars IV claims the Millennium Falcon is "the ship that made the Kessel run in less than 12 pars…ecs", and all the nerd justification attempts aside, it's pretty obvious that someone at the time thought that a "parsec" was a time unit). Both light years and parsecs are based on orbital peculiarities of Earth, so there's no strong reason to prefer one over the other on that basis. Unfortunately, the "natural" unit of length based on universal constants, the Planck length, is inconveniently small for measuring anything at all (it's much, much smaller than an atom ... the radius of a hydrogen atom is over 3 million million million million Planck lengths), let alone the distances between stars. (MORE)
Current contenders are:- LBV 1806-20, The Pistol Star and Cygnus OB2-12. All are over 6 million times more luminous than our own Sun.
The difference between apparent brightness andluminosity is that apparent brightness means that a star may appearto be bright, but only looks bright because of the relativelycloseness a star is to earth. Luminosity is used by astronomers andrefers to the power output of a star. Apparent Brightness …means a star may appear to be very bright butonly look that way because it is relatively close to Earth.Luminosity just refers to the power output of a star. (MORE)
The stellar classification [See link] in order of temperature. Luminosity (L) is based on our Sun. Our Sun is classed as yellow and has a luminosity of 1. . Blue > 30,000 Kelvin. > 30,000 L . Blue to blue white 10,000 -> 30,000 Kelvin. 25 -> 30,000 L . White 7,500 -> 10,000 Kelvin. 5 -> 25 L … . Yellowish White 6,000 -> 7,500 Kelvin. 1.5 -> 5 L . Yellow 5,200 -> 6,000 Kelvin. 0.6 -> 1.5 L . Orange 3,700 -> 5,200 Kelvin. 0.08 -> 0.6 L . Red 1,000 < 3,700 Kelvin. (MORE)
I read on Wikipedia that O-type stars can be a milllion times brighter than our Sun.
Yes, since the distances are so large. You wouldn't be able to easily compare distances or appreciate them if they were in miles or km.
The reference that astronomers use to compare the luminosity ofother stars is the sun's luminosity. The luminosity is denoted inmultiples of the sun's luminosity. For example, the luminosity ofthe star Sirius is 25 times the luminosity of the sun.
A star's luminosity is measured according to the relevance to the sun. Basically for example, if a star is 8,300 degrees Celsius and has a luminosity of 0.001; the luminosity is compared to the sun.
Generally, the larger the star, the more luminous it is. However, luminosity is measured as the visible light of a star as seen at the interstellar distance of 10 parsecs. So a massive star could have a lower luminosity than a bright blue supergiant.
If you refer to the units, both the light-year and the parsec are often used. A light-year is the distance light travels in a year; about 9.5 x 10 12 kilometers (9.5 million million kilometers). A parsec is about 3.26 light-years.
Two different stars with different luminosity may appear to havethe same brightness to an observer because the brighter may be moredistant. This illustrates the need in astronomy to help range distant stars;since apparent magnitude alone will not yield enough information togauge distance. The establ…ishment of a "standard candle" or objectof known brightness can be used for comparison; these can beestablished through various means including statistical models,observation of variable stars, behavior of nearby supernovae, etc.Once the distance of a star is known, the absolute magnitude can bederived from the apparent magnitude using the inverse-square law. (MORE)
Generally, the luminosity of red dwarfs are very low. The largest red dwarf known (Lacaille 8760) has a luminosity 10% of our own Sun, whereas the coolest has a luminosity 1/10,000 th that of our Sun.
Generally speaking, the apparent luminosity would be an inversesquare relationship, which is to say, if the same star was at twicethe distance, a quarter of the light would be reaching theobserver. But absolute luminosity can of course vary without regardto distance from Earth - dim stars can be clo…se, or bright starsdistant, or vice-versa. (MORE)
No, it varies slightly. No, it varies slightly. No, it varies slightly. No, it varies slightly.
There are two in common use; the "light year", which is the distance that light travels in one year, and the "parsec". The parsec is a "parallax-second of arc", the distance that an object would be from Earth if it appears to be separated by one second of arc as viewed from one side of the Earth's o…rbit and from the other side of the Earth's orbit. The "parsec" is approximately equal to 3.26 light years. For intergalactic distances, many astronomers use the "mega-parsec", one million parsecs distance, abbreviated as "Mpc". (MORE)
absolute magnitude is how bright the star actually is andluminosity is how bright it looks.
Typical distances between nearby stars are in the order of a fewlight-years; for example, the closest star to Earth (after our Sun)is at a distance of about 4.2 light-years. Typical distances between nearby galaxies are in the order of ahundred-thousand light-years, to several million light-years. F…orexample, the Andromeda Galaxy is at a distance of about 3 millionlight-years; while that's the closest large galaxy, there areseveral dwarf galaxies that are closer to us. (MORE)
Ceteris Paribus It is the Latin phrase which means: "with all other things remaining the same". Or in economics, "all other factors held constant".
The nearest one is 4.4 light years away ... about 25,866,280,000,000 miles. The other stars range outward from there.
Meters can be used; however, in practice, such distance are usuallymeasured in parsecs, or (in popular astronomical literature) inlight-years.
There are many methods, but the most common one today, for individual stars, is to use the Hertzprung-Russell (H-R) diagram. This diagram is a graph of many stars with luminosity on the y-axis, and temperature on the x-axis. Astronomers have discovered that this graph, coupled with some analysis …of the stars spectrum to determine the strength of spectral lines and gas pressure, allows them to easily identify the class of star. Once the class of a star is known, the luminosity is known. Previous to the HR diagram astronomers had to measure the apparent brightness of the star, and then estimate it's distance from the earth. Using these they could calculate how bright the star really was. Unless you accurately account for the distance to a star, you cannot tell the difference between a dim, close star and a brilliant distant star. (MORE)
These are "variable stars" because their brightness goes up and down with regularity. It was discovered that the frequency depends on the average brightness. So if you see a very dim star behaving as a Cepheid then you can tell how bright it is basically, and then its dimness tells you how far away …it must be. Discovering such stars in distant galaxies was a major factor in figuring out the universe is expanding (Hubble). (MORE)
In the case of a double star, the distance between two stars can be a fraction of an astronomical unit - i.e., a few light-minutes. Otherwise, the distance between the nearest stars in our neighborhood is typically a few light-years, but in some places - near the galactic center, or in globular clus…ters - stars are much closer to each other. (MORE)
There are 2 main factors: the size of the star and its surface temperature. A larger size means a larger surface area to emit light. A higher surface temperature increases the energy emitted. Seen from Earth, the brightness of a star depends on how far away the star is as well as its actual …luminosity. (MORE)
Barnards star is a highly variable star and can have different brightnesses. . Apparent magnitude - 9.54 . Absolute magnitude - 13.22 See related question about the difference between absolute and apparent magnitude
The luminosity depends on what stage of its life cycle the star is in. Also, the apparent luminosity depends on the distance from earth.
At a higher temperature, the star will shine more brightly for each square meter of surface. The total luminosity per square meter is approximately proportional to the fourth power of its absolute temperature. This refers to the energy output, considering all types of electromagnetic waves, not just… visible light. (MORE)
Suppose there are two stars A and B with the same luminosity. If star A is larger then star B then we can conclude that?
A The temperature of star B is lower B The temperature of star A is lower C Star A is more massive D Star B is more massive E Not enough information to conclude anything
A light year is a very long distance, the distance travelled in one year at the speed of light. Astronomical distances are very large though, so light years are used to build a greater appreciation of the distances involved. Km or Miles could be used, but the numbers would be too large to comprehend…. It would be like measuring the distance between Glasgow and Athens using inches or centimetres. (MORE)
How does the gravitational force between 2 bodies changes if mass of one body is doubled but the distance between them remains same?
According to the universal law F=(Gm 1 m 2 )/R 2 If we let m 1
The luminosity for any star is given by the luminosity equation: L=4*pi*sigma*R 2 *(Teff) 4 where sigma is the Stefan-Boltzmann constant (approx. 5.6704x10 -8 W m -2 K -4 ), R is the radius of the star, and Teff is the effective temperature of the star (aka the temperature we observe). …Note: Make sure all of your units match up when calculating this! I.e. if given a radius in km, make sure to convert to m before plugging in, so it matches the Stefan-Boltzmann constant which has units of meters. (MORE)
If the government decreases spending and everything else remainsconstant, there will be a decrease in aggregate demand, leading toa slowdown of economic growth or even leading to a contraction ofthe economy.
scientists use light-years to measure long distances in space. a light year, (abrviated ly) is the distance light can travel.
A star's luminosity is basically how much light it gives out per second. How bright the star appears to us also depends on the star's distance from Earth. So, a particular star can appear dimmer than another star even though it really has a greater luminosity.
Does the distance between the earth and the sun remains the same throughout the earths intire orbit?
Particular places (i.e Antartica) will be either closer or further away depending on the time of year. But if you are counting the whole earth then yes, it remains the same I think.
Visualize this: Cut the earth in half, and look into one half as if you are looking at a circular target. At the center is the center of the earth. Imagine a line from the center straight up to 12 o'clock and another line from center to 3 o'clock, forming a right angle. At three o'clock you have zer…o degrees as measured from the center; this is the equator. The individual degrees upward toward the pole at 90 degrees will define arcs on earth's surface of equal distances. These are degrees of latitude. Lines of longitude are farthest apart at the equator, and they all converge at the poles. So the angular size of any degree will be at its largest at the equator, and will be zero at the poles. (MORE)
It depends on whether the question is about a 2-dimensional object or a 3-d object, and in the latter case whether it concerns the surface area or volume.
There are two principal measurements: the light year and the parsec. The light year, about 9.46 trillion km, is the distance light, at 299,000 kps, travels in a tropical year. The other, which is about 3-and-a-quarter light years, is a figure derived by using the difference in position between two p…oints of the Earth's orbit as the base of a triangle. When the para lex equals one sec ond of arc (1/60th of a minute; 1/3600th of a degree), that a parsec. To avoid having to say "thousand" and "million," really far distances (as between galaxies) are often in terms of "kiloparsecs" and "megaparsecs." (MORE)
Any constellation is a group of stars that appear to form some kindof pattern, but have no connection with each other. They all happen to be inroughly the same direction from us, but they're all at different distances. Sothere's no such thing as a constellation's distance from us.
A good example of a medium size star is the Sun, which is veryaverage. Luminosity is measured by the star's absolute magnitude,which is the magnitude seen from a standard distance of ten parsecs(32.6 light-years), and the Sun's absolute magnitude is +4.7. Afactor of 100 increase in luminosity corres…ponds to 5 magnitudesless (larger magnitudes mean dimmer stars). The brightest starshave absolute magnitudes around -7. (MORE)
Momentum is a simple product of mass time velocity. So if thevelocity doubles the momentum doubles.
Why does the distance between NY and Denver remain the same but the distance from NY to London changes?
New York and Denver are on the same tectonic plate while New Yorkand London are on different plates. In between New York and London,the Mid-Atlantic ridge causes the Atlantic Ocean to grow wider atjust over and inch per year.
Stars all appear to revolve around the sky each day as the Earthrevolves, but relative to each other the stars stay 'fixed'. Thatis because they are so distant it takes years for any of them tomove appreciably.