* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download 2.64 3.26156 8.61 pc ly × =
Tropical year wikipedia , lookup
Cassiopeia (constellation) wikipedia , lookup
Dyson sphere wikipedia , lookup
International Ultraviolet Explorer wikipedia , lookup
History of astronomy wikipedia , lookup
Orion (constellation) wikipedia , lookup
Perseus (constellation) wikipedia , lookup
Geocentric model wikipedia , lookup
Theoretical astronomy wikipedia , lookup
Aquarius (constellation) wikipedia , lookup
Extraterrestrial skies wikipedia , lookup
Alpha Centauri wikipedia , lookup
Corvus (constellation) wikipedia , lookup
Dialogue Concerning the Two Chief World Systems wikipedia , lookup
Canis Major wikipedia , lookup
Observational astronomy wikipedia , lookup
Malmquist bias wikipedia , lookup
Timeline of astronomy wikipedia , lookup
Proxima Centauri wikipedia , lookup
Astr 2020 Problems in Stellar Astronomy Homework Set 5 Solutions Chapter 13 # 45, 48, 49 & 50 13.45. Sirius, the brightest star in the sky, has a parallax of 0.379 arcseconds. What is the distance in parsecs? In lightyears? d (parsec) 1 (arcsec) 1 2.64 pc 0.379arcsec 2.64 pc 3.26156 ly pc 8.61ly 13.48. Sirius is 22 times more luminous than the Sun, and Polaris (the “North Pole Star”) is 2350 times more luminous than the Sun. Sirius appears 23 times brighter than Polaris. How much farther away from us is Polaris than Sirius? What is the distance of Polaris in lightyears? Set the problem up as a ratio of brightness’s: LS BS BS LS rP2 4 rS2 BP LP BP LP rS2 4 rP2 22 LSun rP2 rP 23 2350 23 rS 1 2350 LSun rS2 22 1 rP 49.6 rS Thus Polaris is about 49.6 times farther from us than Sirius. From Appendix 5 of the textbook, Sirius is 8.58 ly from Earth so Polaris is 8.58 ly X 49.6 = 425 ly away. 13.49. Proxima Centauri, the star nearest the Earth other than the Sun, has a parallax of 0.772 arcseconds. How long does it take light to reach us from Proxima Centauri? d (parsec) 1 (arcsec) 1 1.295 pc 0.772arcsec 1.295 pc 3.26156 ly pc 4.225ly Since it is 4.225 lightyears away from us it will take light 4.23 years to reach us. 13.50. Betelgeuse (in Orion) has a parallax of 0.00763 ± 0.00164arcsec, as measured by the Hipparcos satellite. What is the distance to Betelgeuse, and the uncertainty in that measurement? d (parsec) 1 (arcsec) 1 131 pc 0.00763arcsec Find the uncertainty as a fraction of the parallax angle and then multiply the calculated distance by that fraction to get the uncertainty in pc. 0.00164arcsec 0.215 0.00763arcsec 0.215 131 pc 28.2 pc so Distance to Betelgeuse = 131 28.2pc