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PH607lec08
PH607lec08

... A large fraction of disk galaxies have bars: narrow linear structures crossing the face of the galaxy. In barred S0 galaxies the bar is often the only structure visible in the disk. In types SBa and later the bar often connects to a spiral pattern extending to larger radii (e.g. NGC 1300). Viewed fa ...
Finding KBO Flyby Targets for New Horizons
Finding KBO Flyby Targets for New Horizons

... the densest sections of the Milky Way until shortly before the Pluto encounter. Because candidate targets must be observed for 2-3 years to determine a good orbit, targets for the 2015 Pluto flyby trajectory must be identified by about 2012, while the search area is still deep in the Milky Way, thou ...
Unit 11: Dark Energy
Unit 11: Dark Energy

... to study the fuzzy "nebulae" mixed in among the point-like images of stars. They found it difficult to determine what these pinwheel-like objects were because they did not know whether they were nearby small systems where one star was forming or distant large objects as big as the whole Milky Way. D ...
Abstract - UChicago High Energy Physics
Abstract - UChicago High Energy Physics

... We consider massive black hole binary systems and information that can be derived about their population and formation history solely from current and possible future pulsar timing array (PTA) results. We use models of the stochastic gravitational-wave background from circular massive black hole bin ...
Astronomy 250 - University of Victoria
Astronomy 250 - University of Victoria

... Every measured quantity will always have an associated uncertainy. Errors can occur, for example, because of the limitations of the measuring device, because of systematic offsets (see below), because of legitimate dispersions in the data, etc. Example: Suppose you are trying to measure the brightne ...
Chapter 13 Measuring the properties of stars
Chapter 13 Measuring the properties of stars

... The amount of energy emitted by a star each second is the ____ and is measured in ____. A. Apparent brightness; degrees K B. Temperature; degrees K C. Apparent brightness; Watts D. Luminosity; Watts ...
Automated Detection and Analysis of Meteor Events Using Nightly
Automated Detection and Analysis of Meteor Events Using Nightly

... calibration of 17.7. In Figure 9 I compared it to the peak meteor magnitudes obtained using a calibration of 16.2, to see if the shape was similar. The shape is similar however not exactly the same because of rounding and the bin size. The difference is a magnitude shift by +1.5 from the old standar ...
Rich Clusters of Galaxies
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... structure and formation of galaxies. The rich clusters provide an extreme environment for galaxies and allow us to investigate the influence of the environment on galaxy evolution. We can compare galaxy evolution in rich clusters with that in lowdensity environments. They provide constraints on the ...
Lecture20
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... Newer stars have 1% - 4% heavier elements  Old stars have 1/10 to 1/100 as many heavier elements as the Sun ...
Our Expanding Universe
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... The quest for more evidence of the Big Bang theory continued. Physicists John Mather and George Smoot tried to determine what happened during the first trillionth of a second after the Big Bang. They researched the initial expansion of the Universe and the time when the first stars began to shine. I ...
PDF only - at www.arxiv.org.
PDF only - at www.arxiv.org.

... distribution  and  photon  energy  density  fall  off  rapidly  at  the  short  wavelength  end,   the  480  A  shift  from  phototopic  to  scotopic  vision  makes  a  significant  difference  in   the  results.    To  answer  the   ...
M BH
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Here - Astrophysics Research Institute
Here - Astrophysics Research Institute

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Microlensing - Caltech Astronomy
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... To understand the basics of microlensing, consider a small massive object (the lens) situated exactly on the line of sight from Earth to a background star and consider a number of light rays radiating from the star passing the lens at different distances and being bent towards the lens. Since the be ...
Starburst Galaxies - Beck-Shop
Starburst Galaxies - Beck-Shop

... Thirdly, the rate of star formation greatly exceeds the rate sustainable over the galaxy’s lifetime, so that the starburst event must be a relatively transient episode. A classical galaxy like our own has a star-formation rate within the disk of a few solar masses per year, equivalent to perhaps 100 ...
Observational Lower mass limit on stars
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... bright stars that can have their mass determined have been, with the many surveys that are devoted to them. One reason for rarity of accurate M dwarf mass determinations is that small stars seldom eclipse, which means visual binaries must be used (Henry et al. 1999). Also, we need orbits that are ve ...
Starburst Galaxies Encyclopedia of Astronomy & Astrophysics eaa.iop.org T Heckman
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... in the visible and near infrared, and rapid advances in submillimeter astronomy, it is now possible to detect and study such high-redshift galaxies. The ultraviolet-selected galaxies at high redshift strongly resemble similarly selected local starbursts: they have similar values for  SFR , similar ...
Using Python to Study Rotational Velocity Distributions of Hot Stars
Using Python to Study Rotational Velocity Distributions of Hot Stars

... mass can go from 2.5 up to 120 times the Solar mass, their temperatures ranging from 11,000 K up to 60,000 K, and rotation up to 400 km/s. By definition, a star is born when it starts synthesizing Hydrogen into Helium through nuclear fusion. The star performs this nucleosynthesis during some 90% of ...
The star Epsilon UMa, or more commonly known as Alioth
The star Epsilon UMa, or more commonly known as Alioth

... way to remember these classes in order is by remembering that “Only Bored Astronomers Find Gratification Knowing Mnemonics”. Alioth’s spectral type is A in which for these stars the color of the light emitted ranges from a very light blue to white and the approximate surface temperature ranges from ...
Document
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... The “Steady State” theory This theory states that the universe has always existed as it does now and hasn’t changed. The trouble is that the night sky would be completely lit up because of the billions of stars, but it’s not, so… The “Big Bang” theory This theory states that the universe started off ...
The Strikingly Uniform, Highly Turbulent Interstellar Medium of the
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... very broad, 500–600 km s−1 wide, extending throughout the entire galaxy over about 2.5 kpc, with modest shear. Such a large, homogeneous velocity dispersion indicates a highly turbulent medium. W2246-0526 is unstable in terms of the energy and momentum that are being injected into the ISM, strongly ...
The Norma cluster (ACO3627) – II. The near-infrared Ks
The Norma cluster (ACO3627) – II. The near-infrared Ks

... In Section 4, the results of the survey are presented. The K s -band catalogue is described and cross-referenced with the optical catalogue of Woudt & Kraan-Korteweg (2001), and the distribution of the objects and their properties are examined. The LF is derived in Section 5 and compared to those of ...
Lecture 2 Our Place in the Universe (Cont`d)
Lecture 2 Our Place in the Universe (Cont`d)

... This photo shows the Andromeda Galaxy as it looked about 1/2 million years ago. Question: When will we be able to see what it looks like now? ...
OGLE 2008–BLG–290: an accurate measurement of the limb
OGLE 2008–BLG–290: an accurate measurement of the limb

... (l = 1.00◦, b = −3.88◦). As shown by Paczyński & Stanek (1998), it is safe to assume that the mean distance of stars seen in Baade’s Window is similar to the galactic centre distance. Our target’s position lies outside of any OGLE-II fields, but close to field BUL_SC20, and this field is at about t ...
Cosmology with objects from the Hamburg Quasar Surveys
Cosmology with objects from the Hamburg Quasar Surveys

... 1700+6416, the first exceptionally UV bright QSO from the HS (Reimers et al. 1989, 1992), observed with HUT for z < 2.7 (Davidsen et al., 1996). The patches of low HeII opacity below z = 2.9 can be interpreted on the first bubbles of HeIII which finally overlap for z < 2.8 leading to a ‘normal’ HeI ...
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Cosmic distance ladder



The cosmic distance ladder (also known as the extragalactic distance scale) is the succession of methods by which astronomers determine the distances to celestial objects. A real direct distance measurement of an astronomical object is possible only for those objects that are ""close enough"" (within about a thousand parsecs) to Earth. The techniques for determining distances to more distant objects are all based on various measured correlations between methods that work at close distances and methods that work at larger distances. Several methods rely on a standard candle, which is an astronomical object that has a known luminosity.The ladder analogy arises because no one technique can measure distances at all ranges encountered in astronomy. Instead, one method can be used to measure nearby distances, a second can be used to measure nearby to intermediate distances, and so on. Each rung of the ladder provides information that can be used to determine the distances at the next higher rung.
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