How can an astronomer tell the difference between a planetary nebula and a planet?At the end of their lifetime, a planetary nebula is a shell of gas that is ejected from stars similar to our sun. The planetary nebula results from the explosion of a solar-like type star.
What is a white dwarf? Does it produce light in the same way as a star like the SunA white dwarf, also known as a white star, is a small star which is composed of electron-degenerate matter. A white dwarf is very dense and its mass is comparable to that of the Sun. A white dwarf’s volume is comparable to that of the Earth. The white dwarf has a faint luminosity that comes from the stored thermal energy. White dwarfs are comprised of about 6% of all known stars in the solar system.
The white dwarf produces light in the same way as a star like the sun……How can a supernova continue to shine for many years after it explodes
How were pulsars discovered? How do they differ from variable starsWhy do astronomers think that millisecond pulsars are very old?A neutron has a mass of about 1.7 x 10–27 kg and a radius of about 10–15 m. (a) Compare the density of matter in a neutron with the average density of a neutron star. (b) If the neutron star's density is more than that of a neutron, the neutrons within the star are overlapping; if it is less, the neutrons are not overlapping. Which of these seems to be the case for average neutrons within the star? Which do you think is the case at the center of the neutron star, where densities are higher than average?
Imagine that we're somehow able to stand (and survive) at one of the magnetic poles of the Crab pulsar. Describe what you would see. How would the stars appear to move in the sky? What would you see if you looked straight up? What factors make this location a very unhealthy place to visit?
Why is Einstein's general theory of relativity a better description of gravity than Newton's universal law of gravitation? Under what circumstances is Newton's description of gravity adequate?
What is a gamma-ray burster? What is the evidence that gamma-ray bursters are not located in the disk of our Galaxy or in a halo surrounding our Galaxy?
In what way is a black hole blacker than black ink or a black piece of paper?
Why is it unlikely that a black hole has an electric charge?
The orbital period of the binary system containing A0620-00 is 0.32 day, and Doppler shift measurements reveal that the radial velocity of the X-ray source peaks at 457 km/s (about 1 million miles per hour). (a) Assuming that the orbit of the X-ray source is a circle, find the radius of its orbit in kilometers. (This is actually an estimate of the semimajor axis of the orbit.) (b) By using Newton's form of Kepler's third law, prove that the mass of the X-ray source must be at least 3.1 times the mass of the Sun. (Hint: Assume that the mass of the K5V visible star—about 0.5 solar mass from the mass-luminosity relationship—is negligible compared to that of the invisible companion.)
What must happen within a hydrogen atom for it to emit a photon of wavelength 21 cm?
What is the winding dilemma? What does it tell us about the nature of spiral arms?
Do density waves form a stationary pattern in a galaxy? If not, do they move more rapidly, less rapidly, or at the same speed as stars in the disk?
Show that the form of Kepler's third law stated in Box 23-2, , is equivalent to , provided the orbit is a circle. (Hint: The mass of the Sun ( ) is much less than the mass of the Galaxy inside the Sun's orbit (M).)
From what you know about stellar evolution, the interstellar medium, and the density-wave theory, explain the appearance and structure of the spiral arms of grand-design spiral galaxies.