Chapter 9 Quiz Flashcards
What is Parallax?
The effect whereby the position of an object appears to differ when viewed from different positions. This is what is used to determine the distances to stars.
How many light years is one parsec?
3.26LY = 1 Parsec
What were the historical attempts to measure the distance to the stars?
- Celestial Sphere
- Tycho could not measure
- Bessel (1838) made telescopic observations of 61 Cyg ~ 1” over 2 AU’s
What were some modern methods to measure the distance to the stars?
- Large telescopes
- Photographic images
- CCD images
- Hipparcus Satellite
a. Operated from 1989 to 1993 which ahs given
estimates accurate to 5% for 7000 stars.
We now have reliable estimates for stars within
200 PC of the Sun.
5.
The motion relative to background stars that most stars exhibit is called ___.
Proper motion.
Why do stars differ in apparent brightness?
Because stars have various intrinsic brightnesses and distances.
What is apparent magnitude?
the defined visual scale for catalog going from numbers 1(brightest) to 9(dimest). In other words, the brightness of a star seen from the Earth.
What is Absolute Magnitude?
The intrinsic measure of a star if it were 10 parsecs away
What is apparent luminosity?
The apparent luminosity that is visible to the human eye
what is Absolute Luminosity?
The intrinsic measure of energy given off by a star.
what are the rough star distance estimates based on formulas that are good to know?
If m-M > 0, the star is more than 10 Parsecs away,
If m-M < 0, the star is more than 10 Parsecs away, and if m-m = 0, the star is 10 parsecs away.
What were Father Secchi’s astronomical contributions?
He collected Spectra from various stars.
What were Bohr’s Astronomical contributions?
- He developed a model for atoms
2. He developed a model to explain how light is produced by atoms.
What were Cannon’s astronomical contributions?
She surveyed many spectra from stars and categorized them.
Must stars have an absorption Spectra, what are the broad classes of these?
O B A F G K M with subclasses of 0-9
What spectra classification is the sun?
G2
Why do stars have different spectra?
Main Reason:
1. The physical condition of the atoms
Minor Reasons:
1. Different chemical abundances
2. Steller ages.What are balmer lines?
Balmer lines are lines in a spectra that are seen when electrons are past the first orbit in a specific sweet spot orbit. If they pass this sweet spot, the lines will start to fade(This is affected by temperature and the organization of atoms).
What is the Hertzsprung-Russel diagram?
The Hertzsprung-Russel diagram is a series of clusters categorized into specific types of stars, with each star in a specific cluster being the same distance away from the Sun as all the others in its specific cluster.
What types of stars are there in the Hertzsprung-Russel diagram?
- Main Sequence stars: The stars in the main sequence vary, but follow the same pattern. Hot stars are the brightest, while cold stars are the dimmest. Main sequence stars make up 90% of them all.
- Giants: Very bright but cool stars compared to the main sequence stars. (main sequence stars often turn into these as they age.)
- White Dwarfs: Very hot but dim stars when compared to main-sequence stars. (These are very old stars).
- Supergiants: Extremely rare stars that are incredibly luminous compared to the Main sequence stars.
In a Russel graph, stars that are cooler have a ___ number, are associated with ___, and are on the ___ axis.
higher, red, x.
In a Russel graph, stars that are hotter have a ___ number, are associated with ___ and are on the ___ axis.
lower, blue, x.
In a Russel graph, stars that are brighter have a ___ number, and are on the ___ axis.
lower, y.
In a Russel graph, stars that are dimmer have a ___ number, and are on the ___ axis.
higher, y.
