13 Exploring Starlight Flashcards
What is magnitude?
Magnitude is the measure of a brightness of a star
What is the scale of magnitude?
The magnitude difference of 1 corresponds to the fifth root of 100≈2.5
What is apparent magnitude?
Apparent magnitude is how bright a star seems from Earth
What factors affect apparent magnitude?
- The total energy by the star in the visible region
- The distance to the star
- The amount of interstellar gas and dust that reflects and absorbs light
- The amount of light absorbed and scattered by the Earth’s atmosphere
What is absolute magnitude?
Absolute magnitude is how bright a star would be if all stars are 10 parsecs away
How do you calculate absolute magnitude?
M=m+5- 5log(d)
M=absolute magnitude
m=apparent magnitude
How do astronomers find the chemical makeup of a star?
Spectroscopy
What is spectroscopy?
Spectroscopy is when you collect light with the aid of a telescope and then diffract it to create a spectrum.
How do you know what chemicals are in a star?
When you do a spectroscope, there are a set of darker lines. The spectral lines correspond to exact wavelengths at which atoms in the outer layers of stars absorb light; each element has its own unique set of wavelengths
What do astronomers classify stars in?
Spectral types
How do astronomers classify spectral types?
Astronomers examine the ratios of
hydrogen: helium: other elements
What are the different Spectral Types?
O B A F G K M
What is the H-R Diagram?
The H-R diagram is a scatter graph the classify’s stars in accordance to their luminosity, spectral type, colour, temperature and evolutionary stage
What is plotted against each other on a H-R Diagram?
A star’s luminosity or absolute magnitude is plotted against either spectral type or temperature
Where are the main sequence stars found on the H-R Diagram?
The main sequence stars lie in a band running from top left to bottom right
Where are Giants and Supergiants found on the H-R Diagram?
Giants and Supergiants stars lie above the main sequence band
Giant are what colour?
Red or Blue
Where are White dwarf stars found on the H-R diagram?
White dwarfs lie below the main sequence band towards the left
How long is one light year?
1 l.y = 9.5 × 10 ¹²
How long is one parsec?
1 pc = 3.1 × 10 ¹³
How long is one parsec in accordance to light years?
1 pc = 3.26 l.y
What are minutes of arc?
Minutes of Arc is one degree split into 60 minutes of arc. 1 arc minute is further split into arc seconds where one degree is 3600 arc seconds
What technique can we use to figure out the distance to a near star?
Heliocentric Parallax
What is Parallax?
Parallax is when the position of a near object differs greater in comparison to distant objects when viewed from different places