According

Which of the following is least reasonable regarding the magnitude scale: Group of answer choices The numerical difference between a star's absolute and apparent magnitudes is a measure of the distance to the star.   If the Sun were moved to a distance of 10 parsecs, its apparent magnitude would be about 4.8 and it would therefore not be visible to the naked eye.   The fact that Sun's absolute magnitude of 4.8 is greater than the Sun's apparent magnitude of -27 implies that the Sun is a lot closer than 10 parsecs.   Apparent magnitude measures a star's apparent brightness when viewed at the star's actual distance from the observer.   A star's absolute magnitude is its apparent magnitude when viewed from a distance of 10 parsecs.

You measure a star to have a parallax angle of 0.04 arc-seconds. What fraction of a degree is this?

A star is observed to have a parallax of 0.0015".  What is the distance to the star in  units of AU?

How far away is the star Spica, whose parallax is 0.0130?

Calculate by how many times Betelgeuse is brighter than the Sun, if its parallax is 0.006 arcsec, and its apparent magnitude is m = +.5. Can you first use the parallax to calculate the distance and then use the magnitude-distance formula to find the absolute magnitude of Betelgeuse and finally, compare it to the absolute magnitude of the Sun which is -26,74 because other experts used other methods and the answer was not correct.

If we view a star now, and then view it again 6 months later, our position will have changed by the diameter of the Earth's orbit around the sun. For nearby stars (within 100 light-years or so), the change in viewing location is sufficient to make the star appear to be in a slightly different location in the sky. Half of the angle from one location to the next is known as the parallax angle (see figure). Parallax can be used to measure the distance to the star. An approximate relationship is given by d =  3.26 p , where d is the distance in light-years, and p is the parallax measured in seconds of arc. Vega is a star that has a parallax angle of 0.13 second. How far is Vega from the sun? Note: Parallax is used not only to measure stellar distances. Our binocular vision actually provides the brain with a parallax angle that it uses to estimate distances to objects we see. (Round your answer to two decimal places.)  light-years

A nearby star has a parallax of 0.317 arcseconds. How long does it take the light from this star to reach us?

17 Which of the following statements about parallax is not true? A You can demonstrate parallax simply by holding up a finger and looking at it alternately from your left and right eyes. B C D The existence of stellar parallax is direct proof that Earth orbits the Sun. Measurement of stellar parallax allows us to determine distances to nearby stars. The technique of stellar parallax was used by Hubble to determine that the Andromeda Galaxy (M 31) is about 2 million light-years away. Ancient astronomers were unable to measure parallax and used the absence of observed parallax as an argument in favor of an Earth-centered universe.

You measure a star to have a parallax angle of 0.12 arc-seconds What is the distance to this star in parsecs? 8.33 Hint: d = 1/p What is the parallax angle of a different star that is twice as far away as the star from the previous problems? [answer in arc-seconds without including the unit]