Quiz 3 Flashcards
Collects first star catalogue, considered the greatest astronomical observer using Babylonian star records and accurate models of the motion of the sun and moon. Developed trigonometry
Hipparchus
Assigned magnitude of 1-2 brightest stars (metal plate), and divided visible stars into six magnitude classes
Hipparchus making the first determinations of stellar magnitude
System expanded and improved, still the basis of techniques used today
Parsons ratio
Observed from earth, negative is brightest
Apparent brightness
NGC 224, spiral 2.5m ly away from earth, trillion stars, Milky Way mass. Black hole nuclear 3-5 x 10^7. Moving to MW at 301 km/s. Will collide in 3.75 b years
M31 in andromeda
Three parts: disk, nuclear bulge, globular clouds
Spiral galaxy
20%, m31, Milky Way, m 33. type of galaxy. Subdivide to barred and regular
Spiral galaxy
Type of galaxy, 55%
Elliptical
Type of galaxy, 25% Small Magellanic Cloud
Irregular
Demonstrated universe was expanding
Hubble and humason
Observed the effects of dark matter in galaxy clusters
Zwicky
Supply verification of dark tater with galactic rotation curve
Vera Rubin and Kent ford
Should decrease as a function of radius but doesn’t
Galactic rotation
Additional source of gravity around galaxies that don’t make light. has to be taken into account when determining mass
Dark matter
Expanding and accelerating. Led to noble peace prize and the rehabilitation of Einstein’s cosmological constant
Universe
Method of categorizing galaxies, elliptical/irregular to spirals. Not evolutionary. Discovered by Hubble
Tuning fork
Stars and gas orbit in an overall gravitational field, while stars in Ellipticals orbit to maintain shape.
Orbiting
Orbit to maintain shape, center has a supermassive black hole. Hot gas
Elliptical
Cold gas, supermassive black hole
Spiral
Can help find distances in our galaxy to other galaxies. Bound collections of up to a million stars. Luminous and can be seen at great distances. Medium black hole centers. Very old stars.
Globular cluster
Uses up hydrogen, shows age
Main sequence turn off
Used globular clusters to find the size of our galaxy and observed our sun isn’t near the center.
Shapley
Specifies each point on a plane by two coordinates
Cartesian coordinate system
Distance from the y axis is scaled with the x axis
Abscissa
The y coordinate
Ordinate
System of gas, dust, stars with their solar systems
Galaxy
All points of a moving body moving in the same direction
Translational motion
All points of an object circle around an axis
Rotational motion
The squares of the orbital periods of the planets are directly proportional to the cubes of the semi major axes of their orbits
Keplers third law
Astronomical objects that make up the rungs of the cosmic distance ladder: tool for measuring distances. Made of cepheids
Standard candle
Astronomical method for measuring distances to stars. Applied to any main sequence star a spectrum can be recorded for, doesn’t rely on parallax
Spectroscopic parallax
First to realize the Milky Way galaxy was larger than believed, took photographs and observed globular clusters, compact spheres composed of many thousands of stars
Harlow Shapley
Studied solar eclipses, argued there were galaxies outside the Milky Way. Debated with Shapley over the size of the universe
Heber Curtis
