Problem 1: The core of the Sun has a
temperature of 1.5 × 107 K, while...
Problem 1: The core of the Sun has a
temperature of 1.5 × 107 K, while the surface of the Sun
has a temperature of 4910 K (which varies over the
surface, with the sunspots being cooler). Treat the core of the Sun
and the surface of the Sun as two large reservoirs connected by the
solar interior. Nuclear fusion processes in the core produce 3.8 ×
1026 J every second. Assume that 100% of this energy is
transferred from...
Giant planets form beyond the frost line, where the equilibrium
temperature is 150 K. The most...
Giant planets form beyond the frost line, where the equilibrium
temperature is 150 K. The most common type of star that produces
energy by nuclear fusion is a red dwarf star. A typical red dwarf
star has a radius that is 0.5 times the solar radius, and a surface
temperature that is 3600 K.
What is the distance to the frost line for a red dwarf star, in
AU?
Assume the albedo is 0 for the planetesimals.
Recall from your homework last week that the lowest-mass stars
are called "M-dwarfs", which have masses...
Recall from your homework last week that the lowest-mass stars
are called "M-dwarfs", which have masses and diameters that are
typically 1/5th that of the Sun. These stars are also
much cooler than the Sun. The temperature of a typical
M-dwarf star is approximately 3,000 K.
(i) Calculate the wavelength of maximum intensity for the
emission from an M-dwarf and compare it to that of the Sun
(TSun = 5,800 K).
(ii) Sketch the thermal spectrum of each star together on the...
Stars emit radiation whose spectrum is very similar to that of a
blackbody. Imagine two stars...
Stars emit radiation whose spectrum is very similar to that of a
blackbody. Imagine two stars identical in size, each of which is at
the same distance from us. One of the stars appears reddish in
color, while the other one looks distinctly bluish. Based on this
information, what can you say about the relative temperatures of
the two stars? Which is the hotter?
The relative temperature of a star that is red in color is
higher than that of...
Q:
(i) Neutron wavelength: Calculate the wavelength of thermal
neutrons at (a) room temperature and (b)...
Q:
(i) Neutron wavelength: Calculate the wavelength of thermal
neutrons at (a) room temperature and (b) cooled to 4 K (liquid He
temperature). How do these compare with 400 keV electrons and to
typical Brehmmstrahlung radiation from an x-ray tube
(ii) Thermal velocities, de Broglie wavelength: A thermal
neutron has a kinetic energy of 3/2 kT, where T is room
temperature, 300 K. i.e. these neutrons are in thermal equilibrium
with their surroundings. (a) Calculate the thermal velocity of such...
9/ The star Betelgeuse has a wavelength of maximum
emission of 923.5 nm, whereas the star...
9/ The star Betelgeuse has a wavelength of maximum
emission of 923.5 nm, whereas the star Bellatrix has a wavelength
of maximum emission of 131.8 nm. Which star is colder
A/ more info
B/ Bellatrix
C/ Betelgeuse
D/ same temperature
10/ Which of the following correctly lists the spectral
sequence of stars in order of decreasing surface
temperature?
A/ O,B,A,F,G,K,M
B/ M,K,G,F,A,B,O
C/ O,M,K,G,F,B,A
D/ A,B,F,G,K,M,O
11/ How is a star assigned its spectral
type?
A/ The star’s spectrum is...