Midterm Solutions

# Is vega a dwarf main sequence or giant star mbol

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Unformatted text preview: What is the tangential speed of Vega in km/s? Vtan (km/s) = 4.74 µ (“/yr) d(pc) = 4.74 x 0.35 x 7.7 = 13 km/s (d) [5 pts] What is the radial velocity of Vega in km/s? Be sure to indicate whether it is moving toward us or away from us. Vrad = c (Δλ/λ0) = (3 x 105 km/s) x (656.2 nm – 656.3 nm)/(656.3 nm) =  ­46 km/s The line is at a shorter wavelength (toward the blue), so it is blueshifted and therefore moving toward us. Page 5 of 16 Physics 160 Fall 2013 Midterm Exam (e) [10 pts] A0 stars have a bolometric correction Mbol – MV = 0.15. Using the Sun’s absolute bolometric magnitude as a guide, calculate the luminosity of Vega in units of solar luminosities, and its radius in units of Solar radii. Is Vega a dwarf (Main Sequence) or giant star? Mbol = 0.57+0.15 = 0.72 Mbol for the Sun...
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