Astronomers using a 2.0-m-diameter telescope observe a distant supernova? an exploding star. the telescope's detector records 9.1 × 10? 11 j of light energy during the first t s. it's known that this type of supernova has a visible-light power output of 6.0 × 1037 w for the first 10 s of the explosion.
how distant is the supernova? give your answer in light years, where one light year is the distance light travels in one year. the speed of light is 3.0 × 108 m/s.

The “death throes” of stars are amongst the most complex phenomena in all of astronomy, and the “corpses” of stars amongst the most energetic and exotic objects in existence. beginning at the end of the core helium fusion stage in a star’s life, describe in detail the post-main sequence development of both (a) a 1.0 solar mass star, and (b) a 25.0 solar mass star. in what significant ways do they differ? what role does each of these types of stars play in the "star-gas-star" cycle and the evolution of chemical elements in our galaxy?

The electronic structure or chlorine is 2.8.7 what is the electronic structure of fluorine?

Suppose a diode consists of a cylindrical cathode with a radius of 6.200×10^−2 cm , mounted coaxially within a cylindrical anode with a radius of 0.5580 cm . the potential difference between the anode and cathode is 260 v . an electron leaves the surface of the cathode with zero initial speed (v initial=0). find its speed vfinal when it strikes the anode.