Question

How far away is a star that has a parallax of 0.03 seconds of arc? 0.3 parsecs/333.3 parsecs/33.3 parsecs/3.3 parsecs

If you took a measuremnt for a stars position in March, using parallex when is the optimum month for the next measurement? Sept /Oct/ April/ any month

The nearest stars have been catalogued using parallax what is the range of the stars found in this catalogue? 4 to 100 parsecs/ 2 to 1000 parsecs/ 10 to 50 parsecs/ all stars out to 500 parsecs

Compared to close stars, the parallax angle is ________________ for more distant stars. Smaller/ larger/ the same as/ unrelated to distance of stars

Why are astronomers much more interested in the luminosity of a star than its apparent brightness? because the luminosity tells us how bright a star really is, while apparent brightness only tells us how bright it happens to look from Earth/because luminosity can be measured exactly, but apparent brightness can only be roughly estimated/because the luminosity also tells us what elements the star is made of, while apparent brightness cannot tell us a star's chemical make

Answer 1

d = 1/p

d = distance to star, measured in parsecs

p = parallax, measured in arcseconds

Note: 1 parsec is defined as the distance at which a star has a parallax of 1 arcsecond.

1 parsec = 3.26 light years

The star Proxima Centauri has a parallax p = 0.03 arcsecond.

d = 1/0.03 = 33.33 parsec = 108.6 light years

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Look at star, first in April, then in October. Your location changes by 2 AU between these times. Therefore, star's position changes changes relative to background.

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Why are astronomers much more interested in the luminosity of a star than its apparent brightness? because the luminosity tells us how bright a star really is, while apparent brightness only tells us how bright it happens to look from Earth

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When an astronomer rambles on and on about the luminosity of a star she is studying, she is talking about - how much energy the star gives off each second

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Which of the following types of star is the coolest-

Spectral type M - Red giants - Temp < 3,700K

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Astronomers arrange the stars into groups called spectral classes (or types) according to the kinds of lines they find in their spectra. On the HR Diagram these spectral classes are arranged in order of:- ordered by stellar surface temperature

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Which type of binaries only have one visible star but can be determined by looking at motion of that star-

Eclipsing binaries