Astronomical Distsnces & Brightness Flashcards
What is a Parallax angle?
A parallax angle is half the angle moved against distant background stars over 6 months.
What are parallax angles used for?
A parallax is used to measure the distance to nearby stars.
What are parallax angles often measured in?
Arcseconds
How many arcseconds are the in 1°?
3600 arcseconds
If the parallax angle is smaller what does this tell us about the distance of a star?
The smaller the parallax angle the more distant the star
What is a parsec?
Parsec is a unit of distance.
Is the distance to a star with with a parallex angle of 1 arcsecond.
1 parsec = about 3 light years.
What is the formula for the calculating the distance to a star (in parsecs) ?
Distance (pc) = 1 divided by angle (arcsec)
What does a star’s intrinsic brightness depend on?
Size
Temperature
The bigger and hotter a star is the more engery it gives out, so the brighter it is.
What would you see if you looked at two stars with the same intrinsic brightness but one was further away?
The further away star would be dimmer because the energy reaching you gets less.
If a star has a longer pulse period what can we tell about it’s luminosity?
The longer the pulse period, the higher the luminosity.
What factors of a Cepheid variable can an astronomer look at to work out the distance to a Cepheid variable.
Comparing the luminosity worked out by the pulse period & the observed brightness
