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    A galaxy is a large, gravitationally bound system made up of stars, stellar remnants, an interstellar medium of gas and dust and dark matter. Galaxies can range from ten million stars to hundred trillion stars.

    Within galaxies there can also be varying number of star systems, star clusters and types of interstellar clouds. In between celestial objects in galaxies are interstellar medium of gas, dust and cosmic rays. In the middle of all galaxies are supermassive black holes which are thought to be the primary driver of active galactic nuclei.

    Galaxies are categorized according to their shape (visual morphology). Some common shapes are elliptical galaxies, spiral galaxies and irregular galaxies. Galaxies can also combine with nearby galaxies which increases incidents of star formations leading to starburst galaxies.

    There are 170 billion galaxies observable in the universe. Intergalactic space is the space between galaxies which is filled with tenuous gas of average density, less than one atom per cubic meter. Galaxies are organized into hierarchy of associations. These are known as groups or clusters. These groups or clusters usually form larger superclusters. These superclusters will around into sheets and filaments which surround with immense voids.

    Earth resides in the Milky Way galaxy. It is a spiral galaxy. There are approximately 100 – 40 billion stars with a mass of 1.0 – 1.5x1012 solar mass. It has a diameter of 100,000-120,000 light years. Most of the Milky Way is made up of dark matter. Which means it does no emit or absorb electromagnetic radiation. The Milky Way is part of the Local Group of galaxies which forms a subcomponent of the Virgo Supercluster.

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    Active Galaxies, Quasars, Collisions

    1. What is the significance of studying active versus normal galaxies? Explain. 2. Do you think that our galaxy has ever been an active galaxy? Could it have hosted a quasar when it was young? 3. How can collisions affect the shape of galaxies? What evidence can you cite that galactic cannibalism really happens?

    Galaxy distance questions

    The Andromeda galaxy, also known as M31, is the nearest spiral galaxy to the Milky Way and the most distant object visible to the naked eye in the night sky. Andromeda is at a distance of 660 kpc from the Milky Way and it is moving towards the Milky Way at about 120 km s-1, with a collision and merger likely in about 4.5 billion

    Samsung Galaxy S3 vs. iPhone 5

    I need help creating a comparison between S3 and the new iPhone 5. Marketing Strategy! Which one is for you, the Samsung Galaxy S3 or new iPhone 5? Now that Apple's new iPhone has been announced, you may be dithering about whether to upgrade your current iPhone 4S or switch to another platform altogether--Android perhaps.

    Need a Physics genius to help me out with this .

    Suppose an airplane flew east along the equator from the Prime Meridian to the International Dateline; that is, exactly half way around the world. What is its final displacement? Is it the distance covered by its route of flight (12,450 miles) or the distance measured straight through the center of the earth (7,920 miles)? Suppo

    Galaxy redshifts and distances away

    See the attached file for clarity. Q1a) An astronomer observes two galaxies A and B which have redshifts of: Galaxy A = 0.08 and Galaxy B = 0.01 Which galaxy is closest to us and what is its distance away from us? You may assume that the hubble constant is H_0 = 75 km S^(-1) Mpc^(-1) and the speed of light is c= 3.0

    Critical Thinking

    Decide the type of claim that is made in the following statements, whether factual, verbal, interpretive, or evaluative: 1. One reading of people is that they always act out of self-interest and for their own advantage, although they sometimes try to disguise their actions as unselfish and altruistic. 2. Constantinople was


    Suppose a blazar at z=1.00 goes through a fluctuation in brightness that lasts one week (168 hours) as seen from Earth. (a) At what speed does the blazar appear to be moving away from us? (b) Using the idea of time dilation, determine how long this fluctuation lasted as measured by the astronomer within the blazar?s hos

    Distance to a Galaxy using the Hubble Law

    In the spectrum of the galaxy NGC4839, the K line of a singly ionized calcium has a wavelength 403.2 nm. (a) What is the redshift of this galaxy? (b) Determine the distance to this galaxy using the Hubble law with H0 = 73km/s/Mpc.

    Physics: Determine the tangential speed of the sun, magnitude of the net force

    The sun has a mass of 1.99x 10^30 kg and is moving in a circular orbit about the center of our galaxy, the milky way. The radius of the orbit is 2.3x10^4 light years (1 light year = 9.5 x 10^15m) and the angular speed of the sun is 1.1x 10^-15 rad/s A) Determine the tangential speed of the sun B) What is the magnitude of

    Basic Astronomical Questions

    Given the table in the file determine: Which star appears the dimmest which star is the hottest. define absolute magnitude Which star has the highest absolute magnitude? Define Parsec calculate the distance to the stars in the table in parsecs. Calculate the absolute magnitude of Alkaid. See attached file.

    Light Emission: Explaining Discrepancy using Doppler Effect

    The problem below is similar to the problems in chapters 25 & 26 in the Cutnell and Johnson College Physics book so it should be solved in a similar fashion. This is physics-II without calculus: An astronomer is making an observation of a new discovered galactic object. Part of this observation is the analyisis of the light

    Distances to stars are determined.

    How do we calculate or determine the distances to stars? What units do we use and what are the limitations (if any) of the method used for such calculations?

    Resolving Power of Telescope

    The Hubble Space Telescope has a mirror diameter of 2.4m. Suppose the telescope is used to photograph stars near the center of our galaxy, 30,000 light years away, using red light with a wavelength of 650nm. a) What's the distance (in km) between two stars that are marginally resolved? The resolution of a reflecting telescope

    Red-Shift, Metrics, Light-Rays and Galaxies

    Please answer the following (you will need to refer to the attachment for some of the questions): a) Describe what is meant by redshift and how spectroscopic observations of extragalactic objects may be used to deduce their redshifts. b) What is meant by the term metric? The Friedmann-Robertson-Walker metric for a homogeneou

    Speed of Recession of a Galaxy

    Estimate the speed of a galaxy that is 10 billion light-years away. The correct answer is .5c. Can someone show me how it was calculated?

    Cosmology - Luminosity, Brightness, Speed of Recession

    If a galaxy has a luminosity of 6.6x10^39 W and a brightness measured as 1.25x10^-11 W m^-2, How far away is the galaxy in mega parsecs? An absorption line of the element beryllium is observed in the spectrum of the galaxy above as lying 509.4 nm. What is the speed of the recession of the galaxy in km s^1 assuming that the sp

    Eccentricity of a Galaxy

    What is the eccentricity e associated with the elliptical outline of the E6 galaxy? See the attached file.

    Moving from the Geocentric Model to the Heliocentric Model

    Moving from the geocentric model to the heliocentric model required more than one major change in outlook. Among those changes, people needed to accept that the Earth is not the center of the Universe. Discuss how great a change this made in our understanding of our place in the universe.

    Galaxies in the Early Universe

    1) How do we explain that galaxies in the "early Universe" were smaller and relatively more abundant than their modern counterparts?

    size of object located at a distance 10 km angular size

    What is the size of an object located at a distance10 km if it has an angular size A of 2 degrees. and Use hubbles law to determine the distance to a galaxy cluster in megaparsecs with a rescession velocity of 14,200 km/sec.

    Angular Variables and Tangential Variables

    Our sun rotates in a circular orbit about the center of the Milky Way galaxy. The radius of the orbit is 2.2 1020 m, and the angular speed of the sun is 1.2 10-15 rad/s. (a) What is the tangential speed of the sun? (b) How long (in years) does it take for the sun to make one revolution around the center?

    Black Hole

    7. The Sun Rotates around the Milky Way Galaxy at a speed of a. 250 Km / sec and it makes an orbit in 20 Million years b. 20 Km / sec and it completes an orbit in 220 Million years c. 250 Km / sec and completes an orbit in 220 Million years d. 250 Km / sec but the time to complete an orbit can vary subs

    Physics Problems: Black-Body

    Question 2 Clearly show your working in any calculation and express your answers to an appropriate number of significant figures. (a) A proton of mass mp = 1.673 × 10−27 kg and electric charge e = 1.602 × 10-19 C, and an electron of mass me = 9.109 × 10-31 kg and electric charge −e = −1.602 × 10-19 C,

    number of objects encountered as moving from the sun

    As you move from the sun, how many of each object is encountered Ly=light-year Distance from sun Number of stars Number of dwarf galaxies Number of large galaxies Number of galaxy group Number of superclusters 1 ly 1 5 ly 3 12.5 ly 33 20 ly 83 50 ly 133 250 ly 260000 5,000 ly 600million

    Several questions on relativistic mechanics

    5-Three galaxies are aligned along an axis in order A, B, C. An observer in galaxy B is in the middle and observes that galaxies A and C are moving in opposite directions away from him, both with speeds 0.59c. What are the speeds of galaxies B and C as observed by someone in galaxy A? c (galaxy B) c (galaxy C) 6-A spacecr

    Traveling Near the Speed of Light

    There are a pair of identical twins. One remains on earth while the other goes on an extended trip through the galaxy. During this trip, the traveler averages a speed of 0.95 times the speed of light. If this trip lasts for a period of one year, as measured by the traveler, what is the age difference between the twins when th

    Gravitation and Black Holes

    At the Galaxy's Core. Astronomers have observed a small, massive object at the center of the Milky Way galaxy. A ring of material orbits this massive object; the ring has a diameter of about 17.0 light years and an orbital speed of about 130 km/s. (See attached file for full problem description) A) Determine the mass of the