# a bright source doubles its luminosity over the course of a week. how large is the sourse?

by Susan Rohan 10 min read

## How is the brightness of a StAR related to its distance?

Oct 18, 2016 · The flare then died away over the course of a half hour or so back to its baseline level. The X-ray luminosity of the source during the peak approached 1 x 10 e41 ergs/s, or about 30 times the X-ray luminosity of the entire Milky Way Galaxy. The host of the flare is a red, rather faint globular cluster within NGC 4636.

## What is the intensity of a lightbulb at 2m away?

Sep 30, 2019 · Precalculus questions and answers. 7. The apparent brightness B of a light source (measured in W/m2) is directly proportional to the luminosity L (measured in W) of the light source and inversely proportional to the square of the distance d from the light source (measured in meters). (a) Write an equation that expresses this variation.

## How does the luminosity of a galaxy change?

The main source of energy for a star as it grows to become a red giant is. ... The extremely bright center of a distant galaxy thought to be powered by a massive black hole. If an object doubles its luminosity in 10 hours how large can the emitting source of light be.

## Do All Stars of the same luminosity have the same brightness?

A: Every object that emits light has some intrinsic brightness (luminosity) but its apparent brightness changes with distance B: An object emits light in all directions around it and the light is diluted through spheres around the light source C: The intensity of the light drops off with the square of the distance

## How do you measure the luminosity of a star?

If they know the star's brightness and the distance to the star, they can calculate the star's luminosity: [luminosity = brightness x 12.57 x (distance)2]. Luminosity is also related to a star's size. The larger a star is, the more energy it puts out and the more luminous it is.

## How is the apparent brightness of a star related to its luminosity?

Luminosity is the rate at which a star radiates energy into space. Apparent brightness is the rate at which a star's radiated energy reaches an observer on Earth. Apparent brightness depends on both luminosity and distance.Jan 14, 2020

## Does luminosity change with distance?

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.

## How large is a quasar?

Quasars also have the accretion disc of matter falling into the supermassive black whole which generate the energy. So, a quasar would typically be the size of the solar system. The Sun has a diameter of 696,000km , so a quasar would be in the order of 4,000 times the diameter of the Sun.Jan 15, 2016

## Which of the following correctly describes the luminosity of a star?

Brandon learns that a star's luminosity is a measure of the star's absolute brightness, and is determined by a combination of the star's physical properties.

## What is the luminosity of our sun?

The luminosity of the Sun is 3.846 × 1026 watts (or 3.846 × 1033 ergs per second). Luminosity is an absolute measure of radiant power; that is, its value is independent of an observer's distance from an object.

## How does luminosity calculate distance?

Using brightness and luminosity to get distanceThe luminosity of the lightbulb is L = 100 W.The brightness is b = 0.1 W/m2.So the distance is given by d2 = (100 W)/(4 Pi x 0.1 W/m2).Since 4 Pi is approximately 10, this is d2 = (100 / 1) m2.Thus d2 = 100 m2.We now know what d2 is. ... So d = 10 m.

## What is the luminosity distance formula?

More generally, the luminosity, apparent flux, and distance are related by the equation f = L/4`pi'd2. If we measure a star's parallax and its apparent brightness, we can determine its luminosity, which is an important intrinsic property.Jan 11, 1997

## How would its luminosity change if the distance between Earth and the star were to double?

If, for example, we have two stars of the same luminosity and one is twice as far away as the other, it will look four times dimmer than the closer one. If it is three times farther away, it will look nine (three squared) times dimmer, and so forth. Alas, the stars do not all have the same luminosity.

## What is the luminosity of the most powerful quasars?

At 430 trillion solar luminosity, this new quasar is 7 times brighter than the most distant quasar known (which is 13 billion years away). It harbors a black hole with mass of 12 billion solar masses, proving it to be the most luminous quasar with the most massive black hole among all the known high-redshift quasars.Feb 25, 2015

## What is a quasar quizlet?

What is a Quasar? the extremely bright center of a distant galaxy, thought to be powered by a massive black hole.

## How is a quasar formed?

A quasar is formed when a super massive black hole at the centre of a galaxy has enough material around it to fall into the accretion disc to generate the energy to power it. The only galaxies with enough material to create a quasar are young galaxies and colliding galaxies.Dec 27, 2015

## What is the luminosity of a quasar?

The brighter quasars have a luminosity of 10 15 L Sun ~ 100,000 x more luminous than the Milky Way.

## What is the bright radio source called?

The innermost 1,500 light years of the Galactic Centre (at radio wavelengths)#N#The bright radio source called SGR A (Sagitarius A) is the centre of the galaxy.#N#The bright region of SGR A seen in this image is about 100 light-years across.

## What is the spectrum of a galaxy?

The spectrum of a galaxy is mainly the sum of the spectra of all the stars (absorption spectrum) as well as the dust and Hydrogen gas. The luminosity of a normal galaxy does not change much over short periods of time.

## How many masses does a black hole have?

a gigantic black hole (or Supermassive black hole) with a mass in the range of one million to one billion solar masses can also have an accretion disk which emits radiation.

## Which galaxy has a black hole?

Observations of nearby galactic centres (such as the Milky Way and Andromeda) have shown evidence that most galaxies have a supermassive black hole at their centre. The Milky Way's central black hole is only one million times the mass of the Sun, so it may not have been as bright as a quasar when it was young.

## What are the different types of galaxies?

Some different types of active galaxies are: Radio Galaxies, Seyfert Galaxies, BL Lac Object s (also known as Blazars), and Quasars.

## Where do radio waves come from?

The contour lines show where radio waves are emitted. The radio emission originates from giant jets which point in directions perpendicular to the dusty disk. The radio emission extends out much further than the visible part of the elliptical galaxy. The length of the radio jets are about 10 kpc.

## How far away would a star have to be to have a parallax of 1 arcsecond?

With a baseline of one AU, how far away would a star have to be to have a parallax of 1 arcsecond? The answer turns out to be 206,265 AU, or 3.26 light-years. This is equal to 3.1 × 10 13 kilometers (in other words, 31 trillion kilometers). We give this unit a special name, the parsec (pc)—derived from “the distance at which we have a par allax of one sec ond.” The distance ( D) of a star in parsecs is just the reciprocal of its parallax ( p) in arcseconds; that is,

## What is the total energy emitted per second by a star called?

The total energy emitted per second by a star is called its luminosity . How bright a star looks from the perspective of Earth is its apparent brightness. The apparent brightness of a source of electromagnetic energy decreases with increasing distance from that source in proportion to the square of the distance—a relationship known as the inverse square law. Thus, the determination of apparent brightness and measurement of the distance to a star provide enough information to calculate its luminosity.

## What are the characteristics of a star?

Perhaps the most important characteristic of a star is its luminosity —the total amount of energy at all wavelengths that it emits per second. Earlier, we saw that the Sun puts out a tremendous amount of energy every second. (And there are stars far more luminous than the Sun out there.) To make the comparison among stars easy, astronomers express the luminosity of other stars in terms of the Sun’s luminosity. For example, the luminosity of Sirius is about 25 times that of the Sun. We use the symbol LSun to denote the Sun’s luminosity; hence, that of Sirius can be written as 25 LSun. In a later chapter, we will see that if we can measure how much energy a star emits and we also know its mass, then we can calculate how long it can continue to shine before it exhausts its nuclear energy and begins to die.

## How does light travel through space?

As waves expand, they travel away from the bulb, not just toward your eyes but in all directions. They must therefore cover an ever-widening space. Yet the total amount of light available can’t change once the light has left the bulb. This means that, as the same expanding shell of light covers a larger and larger area, there must be less and less of it in any given place. Light (and all other electromagnetic radiation) gets weaker and weaker as it gets farther from its source.

## Which star is closer to the Sun?

One of the nearest stars, Alpha Centauri A , emits about the same total energy as the Sun. But it is about 270,000 times farther away, and so it appears about 73 billion times fainter. No wonder the stars, which close-up would look more or less like the Sun, look like faint pinpoints of light from far away.

## How accurate is stellar parallax?

The measurements of stellar parallax were revolutionized by the launch of the spacecraft Hipparcos in 1989, which measured distances for thousands of stars out to about 300 light-years with an accuracy of 10 to 20%. However, even 300 light-years are less than 1% the size of our Galaxy’s main disk.

## How big is the Earth's diameter?

What happens if we put it in terms that might be a little more understandable, like the diameter of Earth? Earth’s diameter is about 12,700 km.