A certain bright star has a temperature of 10,600 K, and is believed to have a radius of order 70 times the radius of the Sun. At what orbital radius would a planet have a flux of radiation comparable to that on our Earth – ie – habitable like the Earth? At this stellar temperature, what colour does the star have?
a) For this problem, we can consider the star as a perfect black body.
So, the energy emitted by it per unit area is
If the planet has a radius r, the total power emitted by the planet is
If the planet is at a distance R from the star, the flux received by the planet per unit area is
We know that T = 10,600 K
r = 70*rsun = 70*696*10^6 = 4.872*10^10 m
For earth, F = 1388 W/m^2
So,
b) The wavelength of radiation is given by
This light will be in the UV region.
So, the color of the star as it appears to human eye will be blue.
A certain bright star has a temperature of 10,600 K, and is believed to have a...
6. The bright star Arcturus in the constellation Boötes has a surface temperature about 0.74 times that of the Sun. Its luminosity is about 170 times that of the Sun. (a) What is Arcturus’ radius compared to the radius of the Sun (in units of solar radii, ?⊙)? (b) What type of star is Arcturus (a dwarf, a giant, or a supergiant)? Explain your reasoning.
Imagine we find a star that has the same radius as the Sun, but its temperature is 9.6 times greater. That star should be _____ times as luminous as the Sun. Suppose we find a planet with an orbital period of 200 days around a star with the same mass as the Sun, but only 75 percent as luminous. What is the planet’s semi-major axis, in AU?
Questions 9 & 10 Tasks to complete: Fill out Table 2, using the Habitable Planet Classification Chart once Table 2 is completely filled in, answer the questions 9 and 10. To fill in the table: For Star Type, you will need to reference the star temperatures addressed in the write-up above. If the star temperature of the planet is within the range of an F, G, or K type star, it gets a “Yes” in that column. For Planet Habitable...
Planet X has 20 times the mass of the earth and 3 times the earth's radius. It orbits star Y at a distance of 8 AU, where 1 AU is the earth-sun distance. Star Y has twice the mass of our sun. (a) What is the orbital period of Planet X in years? (b) An astronaut has an earth weight of 120 lbs. What is her weight on the surface of planet X?
Betelgeuse, a bright red star in the constellation Orion, has a luminosity that is 100,000 times that of the Sun However, the surface temperature of Betelgeuse is only 3000 K. Assuming that the emissivity of stars is 1, find the radius of Betelgeuse.
8. A certain star has a mass four times that of our Sun. A planet in orbit around that star has a semimajor axis of 0.45 AU and an eccentricity of 0.32. What is the rate of precession of this planet's "perihelion"?
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The brightest star in the northern celestial hemisphere has a surface temperature of about 4300 K and it is 170 times more luminous than the Sun. Calculate the radius of the star in units of the radius of the solar radius (round the result to the nearest integer) In the calculation, you may assume that the Sun has a radius of 7E8 meters and a luminosity of 3.8E26 watts.
Satellite A has twice the mass of satellite B, and circles in the same orbit. Compare the two satellite's speeds. The speed of B is twice the speed of A. The speed of Bis half the speed of A. A. The speed of Bis one-fourth the speed of A. The speed of B is equal to the speed of A. The speed of Halley's Comet, while traveling in its elliptical orbit around the Sun, O is constant increases as it...
The hottest ordinary star in our galaxy has a surface temperature of 53,000 K. What is the peak wavelength of its thermal radiation?