Consider a star with more brightness at 280 pc from the Sun. Suppose this star gets exploded as a supernova at a temperature of 18000 K. The absolute bolometric magnitude of this supernova is -12.24. Calculate its diameter by assuming a sphere at maximum light. (Assume the luminosity of Sun as 3.8×1026 W, the mass of the sun as 1.9 ×1030 kg, and surface temperature of Sun as 5778 K). (a) 1.7×108 km (6) 3.5x108 km (c) 5.2x108 km (d) 6.9 x108 km

In a star of 1 solar mass (M☉), the core hydrogen burning phase, also known as the main sequence phase, lasts for approximately 10 billion years. Suppose there's a star of 15 solar masses (M☉). Stars of higher mass burn through their hydrogen at a faster rate, following an approximate relation that the lifetime of a star on the main sequence (T) is proportional to its mass (M) raised to the power of -2.5 (T ∝ M^-2.5). Calculate approximately how long this 15 solar mass star would remain in the main sequence phase, compared to the 1 solar mass star.

The mass-luminosity relation describes the mathematical relationship between luminosity and mass for main sequence stars.  It describes how a star with a mass of 4 M⊙ would have a luminosity of ______ L⊙. If a star has a radius 1/2 that of the Sun and a temperature 4 that of the Sun, how many times higher is the star's luminosity than that of the Sun? (If it is smaller by a factor of 8, you would write 0.125 because 1/8=0.125) If a star has a radius 2 times larger than the Sun's and a luminosity 1/4th that of the Sun, how many times higher is the star's temperature than that of the Sun? (If it is smaller by a factor of 8, you would write 0.125 because 1/8=0.125) If a star has a surface temperature 2 times lower than the Sun's and a luminosity the same as the Sun, how many times larger is the star than the Sun? (If it is smaller by a factor of 8, you would write 0.125 because 1/8=0.125)

We will take a moment to compare how brightly a white dwarf star shines compared to a red giant star. For the sake of this probler, lets assume a white dwarf has a temperature around 10,000 K and a red giant has a temperature around 5,000 K. As for their stellar radii, the white dwarf has a radius about 1/100th that of the Sun and a red giant has a radius around 100 times larger than the Sun. With this in mind, how does the luminosity of a red giant star compare to that of a white dwarf (Hint: do not try to enter all of these numbers into the luminosity equation fit won't go well); instead, remember that you are only interested in the ratio between the two, so all common units and components can be divided out)? Please enter your answer in terms of the luminosity of the red giant divided by the luminosity of the white dwarf and round to two significant figures. Also, please avoid using commas in your answer. A Moving to another question will save this response. Question 1 of 32 >» 31…

If Betelgeuse is a M2 type star, what is the approximate temperature of the star in K?

If a 1.40 MSun neutron star has a radius of 10.0 km, what is the radius (in km) of a 2.15 MSun neutron star? (Use the mass-radius relationship  R ∝ M−1/3)   What is the escape velocity (in km/s) from the surface of a 1.5 M neutron star? From a 3.0 M neutron star? (Hint: Use the formula for escape velocity,  Ve =    2GM r ;  make sure to express quantities in units of meters, kilograms, and seconds. Assume a neutron star has a radius of 11 km and assume the mass of the Sun is 1.99 ✕ 1030 kg.) 1.5 M neutron star km/s3.0 M neutron star km/s

For a 1 solar mass white dwarf with a radius of 6000km, calculate the momentum and kinetic energy (in units of electronvolts) of an electron in the highest occupied electron state. Assume the star consists only of carbon and has a uniform density. Calculate the momentum and kinetic energy of a neutron in the highest occupied neutron state for a 2 solar mass neutron star with a radius of 10km. Assume that the star has a uniform density and consists only of neutrons.

 Q/ b) Vega Star of radius (1.6832) million km emit a) thermal radiation as a black body radiation at temperature of (18500 K). Calculate the Luminosity of this star. [o is Stefan-Boltzmann constant = 5.67 *x 10-5 erg cm-2 K-4 s-1]

During the collapse of a supernova explosion, calculate the change in gravitational potential energy associated with the core size. Assume a typical core mass of 1.4 Msun and an initial radius of 1000 km.

A supernova remnant is now 3.85 pc in radius and is expanding at 3,350 km/s. Approximately how many years ago did the supernova occur? (Note: 1 pc = 3.1 ✕ 1013 km and 1 yr = 3.2 ✕ 107 s.)