ASTRON 2B03 Lecture Notes - Lecture 5: Elliptical Galaxy, Spiral Galaxy, Galactic Center

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goldbeaver755

12 Oct 2018

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A (cid:498)spiral galaxy(cid:499) similar to the milky way: our own sun is located on the outskirts of the milky way about 25,000 light years from the galactic center. Spirals: flat, rotating disk of stars, gas and dust, have visible spiral arms, lots of new stars are forming in the spiral arms, order to star rotations. Elliptical: 3-dimensional (not flat, no visible spiral arms, not much rotation at all, not forming new stars, stars on (cid:494)random orbits(cid:495), picture a swarm of bees. Ellipticals: galaxies are usually found in groups, these groups are gravitationally bound to each other. Clusters: sometimes galaxies are in very big groups called clusters of galaxies (biggest may have thousands of member galaxies, the supergiant ellipticals in this cluster have perhaps a trillion stars each. Galaxy clusters: collection of many galaxies (hundreds to a thousand, millions of light years across in size, weighs the same as trillions of suns.

Related Questions

Which of the following statements does not use the term light-year in an appropriate way?
A) A light-year is about 10 trillion kilometers.
B) It's about 4 light-years from here to Alpha Centauri.
C) It will take the Voyager spacecraft about 20,000 years to travel just 1 light-year.
D) The Milky Way Galaxy is about 100,000 light-years in diameter.
E) It will take me light-years to complete this homework assignment.

pucebuffalo889

Astronomy Parallax Lab

SCENARIO: Your lab group is planning an expedition to measure the distance to Mars by carefully measuring its position in the sky from two locations simultaneously when it is next at “opposition” (that is, when it is exactly opposite from the sun in the sky) on October 13, 2020. For the best, and most straightforward distance determination with the parallax method, Mars should be high in the sky (as near to your zenith as possible). This can be done by observing Mars: (a) from locations whose LATITUDES are similar to the DECLINATION of Mars at the date of measurement and (b) at the time of night when Mars is highest in the sky.

1a). Determine the Sky Coordinates of Mars on the date of opposition. The relevant coordinate is the Declination (RA/DE J2000 coordinates should be used) – this is the sky coordinate analogous to Latitude on the Earth’s surface. (Note, it is ok to determine these coordinates for Mars from anywhere on Earth for this initial measurement)

Mars DECLINATION on October 13, 2020: ___________________________

Your lab team needs to send observers to two cities that:

(a) have latitudes that are similar to the declination of Mars on that date (within 20 degrees); and

(b) have nearly the same longitude (that is, are nearly due North-South from each other (hint, you will need to go close to the equator!).

1b). Choose two of the cities below and use google maps, google earth or another online resource to record their names and Latitudes.

Melbourne, Australia	Kampala, Uganda	Tokyo, Japan
Omaha, NE, USA	Mumbai, Italy	Khartoum, Soudan

1c). At what time should you measure the sky coordinates (right ascension and declination) to get the most accurate possible parallax distance?

plumantelope954

ASTRON 2B03 Lecture Notes - Lecture 5: Elliptical Galaxy, Spiral Galaxy, Galactic Center

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