Geography, 29.07.2019 21:00 anne010p4bffk

Suppose a star has the same luminosity as our sun (3.8×1026watts) but is located at a distance of 20 light−years . what is its apparent brightness?

Answers: 1

Show answers

Answers

The apparent brightness is defined by how much light we get pretty much. The formula is:
$AB= \frac{L}{4\pi d^2}$
This takes into account that the light is spreading out to a sphere that has the surface given by 4πd^2.
We have that d=20 ly and 1 ly is 9.46*10^12 km or 9.46*10^15m.
Hence, d=20*9.46*10^15=189.2 *10^15 m
Now, we can substitute the d value and calculate that L=8.45184* $10^{-10}$ W/m^2

Answer from: kita2911

The apparent brightness is $8.667\times{10^{-33}}{\text{ W/}}{{\text{m}}^{\text{2}}}$

Further Explanation:

The apparent brightness of a light source is measured by dividing luminosity with surface area of sphere with radius that is equal to the distance from source of light. The formula for calculating apparent brightness is:

$F{\text{}}={\text{}}\dfrac{L}{{4{\text{}}\pi{\text{}}{d^2}}}{\text{ }}$

Where,

d: the distance from source of light.

L: luminosity.

Calculate the apparent brightness:

$\begin{aligned}F&=\dfrac{L}{{4\pi d^2}}}\\ &=\frac{{3.8\times1026{\text{watts}}}}{{4\pi{{\left( {{\text{189}}{\text{.2}}\times{\text{1}}{{\text{0}}^{15}}{\text{m}}}\right)}^2}}} \\&=\frac{{3898.8}}{{4.498\times{{10}^{35}}}}\\&=8.667\times{10^{-33}}{\text{ W/}}{{\text{m}}^{\text{2}}}\end{aligned}$

The apparent brightness is $8.667\times{10^{-33}}{\text{ W/}}{{\text{m}}^{\text{2}}}$

Working Notes 1:

Conversion of distance in light year to meters:

$\begin{gathered}{\text{d}}=20\times{\text{9}}{\text{.46 }}\times {\text{1}}{{\text{0}}^{15}}\\=189{\text{.2}}\times{\text{1}}{{\text{0}}^{15}}{\text{m}}\end{gathered}$

Learn more:

1. Learn more about Australia

2. Learn more about South America

3. Learn more about North America

Answer details:

Grade: High School

Subject: Astronomy

Chapter: Luminosity

Keywords: Suppose a star has the same luminosity as our sun (3.8×1026watts) but is located at a distance of 20 light−, what is its apparent brightness.

Answer from: Quest

The latin america and caribbean (lac) region encompasses countries with great environmental issues. the southern portion of central america to the caribbean's part, including south america presses the major environmental issues like deforestation and habitat subsistence. the requirement of the whole country and the pressure of export is being done by this region as it possess the soil with highest fertility rate and maximum strength which could us in modifying the various technology for the humankind. because of deforestation, we take animal shelters away from them, so the major issue occurs again which we known as "habitat subsistence". government has to set the target according to the capacity of a certain region which would not affect the environment. then, businesses and organizations have to understand their roles and need to divide the task into several groups (one for each, according to their natural capacity), individuals can the government or statuary body by just following their guidelines and never harm or exploit the environment for our own use.i really hope this you out!

Answer from: Quest

a. narmada me brainlist

Another question on Geography

Geography, 22.06.2019 23:00

The climate in the temperate zone is cold in summers and warm in winters very cold year-round very warm year-round warm in summers and cold in winters

Answers: 1

Answer

Geography, 23.06.2019 05:30

Landmasses on a flat map look distorted because

Answers: 1

Answer

Geography, 23.06.2019 10:00

What are the answers for the following questions?

Answers: 1

Answer

Geography, 23.06.2019 13:00

Which country in the video has the highest population growth rate?