Question

The following questions use the mass and radius of a white dwarf (M=1.0 solar mass, R=6000 km) and neutron star (M=1.5 solar mass, R=12 km). 7. Consider an object with a temperature of T=107 K, and an X-ray luminosity of 1030 Watts. What radius would this object have? Is this object more likely a white dwarf or a neutron star?

Answer #1

Here we have been given the Mass and Radii for white dwarf and a neutron star thus we just need to find these values for the object we are considering and then compare these values to find the desired result.

The relationship between luminosity (in watts), Radius (in m) and Temperature of a body (in K) is given by following relationship:

where S is the stefan boltzman constant. Now putting the values we get:

Comparing the values we can see that this object is more likely to be a neutron star.

A white dwarf star (R = 0.0073 R⦿, M= 1.4
M⦿) goes over the Chandrasekhar limit and collapses to a
neutron star (R=10 km). At that point the collapse stops. The
collapse time is 0.1 seconds.
A) Calculate the total amount of energy liberated from the star
in the collapse.
B) Estimate the luminosity (energy liberated/collapse time).
C) If the white dwarf was originally spinning with a 1.3 day
period, what would the period of the neutron star rotation be?

a) Calculate Eddington luminosity for a neutron star (M = 1.4M),
a white dwarf (M = 0.7M), supermassive black hole (M = 4.1 × 106M)
in the center of our Galaxy. M is the typical notation for the
solar mass (look up the M value on the web). Express your answer in
ergs/s.
b) Assuming distances of 2 kpc (typical distance to an accreting
neutron star), 80 pc for a white dwarf , and 8 kpc for the
supermassive black...

If both a neutron star and a white dwarf have a total mass of
1M®. If the radius of the white dwarf is 6 x
106 m and the neutron star has a radius of 8 km.
What is the density of the neutron star?
Compare the surface gravity of both stars?
Assuming the neutron star is entirely made up of neutrons and
the interparticle separation of a gas of density n is l
͌ n -1/3. How far apart are...

In an X-ray burster, the surface of a neutron star 10 km in
radius is heated to a temperature of 3 ×
107 K. (a) Determine the wavelength of maximum
emission of the heated surface, assuming it radiates as a
blackbody. In what part of the electromagnetic spectrum does this
lie? (b) Find the luminosity of the heated neutron star. Give your
answer in watts and in terms of the luminosity of the Sun. How does
this compare with the...

Assume the earth is a uniform sphere of mass M and
radius R. As strange as it may sound, if one can dig a
long tunnel from one side of the Earth straight through the center
and exit the other end, any object falling into the tunnel will
appear at the other end (i.e. the opposite side of the Earth) in
just 2530 s (42.2 min). Call that time t. Let t
be a function of G, M, and R,...

3/ which of the following stellar properties is the most
fundamental to a star’s main-sequence and post-main sequence
life?
A/ temperature
B/ mass
C/ luminosity
D/ radius
4/ Stars Moppit and Boppit orbit each other as members of a
binary star system. Their period of rotation about their combined
centre of mass is 10 years. The semi-major axis of Boppit’s orbit
around the centre of mass is 15.25 AU. What is the combined mass of
Moppit and Boppit?
A/ Mmoppit...

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