Astronomy | Astrophysics Answers

Using parallax, you establish that a particular star cluster is 30 parsecs from the Earth. You measure the colours and fluxes of all the main sequence stars in this cluster.

You next want to work out the distance to a dwarf galaxy orbiting our own Milky Way. You measure the colours and fluxes of the stars in this galaxy, and find that they have fluxes that are typically one million times fainter than comparable colour stars in the nearby star cluster.

What is the distance to the dwarf galaxy (in parsecs)

Our solar system is about 8.3 kpc from the centre of our galaxy. Using Newtons universal gravitation law and kepler's third law, calculate the approximate mass of our milky way if we know that the orbital velocity of the sun around the centre of the galaxy is 225 km/s

The star of a distant solar system explodes as a supernova. At the moment of the explosion, an resting exploration spaceship is 15 AU away from the shock wave. The shock wave of the explosion travels with 25000 km/s towards the spaceship. To save the crew, the spacecra makes use of a special booster that uniformly accelerates at 150 m/s2 in the opposite direction. Determine if the crew manages to escape from the shock wave. (Neglect relativistic eects.)

Acceleration due to gravity at the earth s surface is 9.8ms-2At what height above the earth is the g equal to 9.8/4ms-2

(i)           The resultant gravitational force exerted upon the body at this point is zero. Calculate the distance R of the body from the centre of the Earth given that

r = 3.9 × 107 m and M_E = 81 M_M

4d) Explain the need to postulate the existence of dark matter in the universe.

4c) Describe the nature of the central engine in an AGN.

4b) Calculate the half-width of a spectral line of wavelength  = 550 nm when the

temperature of the gas is 6  105 K. Assume H atoms to be emitters.

4. a) Explain Hubble’s scheme of galaxy classification with the help of a diagram.

Describe the prominent features of spiral galaxies.

3e) Discuss the rotation curve of our Galaxy. What inferences can be drawn from it

about the structure of our Galaxy?