Altitude and Azimuth 4 page
... Astronomers require a coordinate system for the sky to find objects in the same way that a navigator or geographer needs a coordinate system to find objects on the Earth. Navigators and geographers use latitude and longitude to find their way around on the surface of the Earth. Astronomers, though, ...
... Astronomers require a coordinate system for the sky to find objects in the same way that a navigator or geographer needs a coordinate system to find objects on the Earth. Navigators and geographers use latitude and longitude to find their way around on the surface of the Earth. Astronomers, though, ...
Publisher: Emily Barrosse Acquisitions Editor: Kelley Tyner
... a result, the rate at which hydrogen is fusing into helium in a shell around the core increases again. The star grows still larger. The outer layers, this time, continue to drift outward until they leave the star. Perhaps the outer layers escape as a shell of gas. Or perhaps they drift off gradually ...
... a result, the rate at which hydrogen is fusing into helium in a shell around the core increases again. The star grows still larger. The outer layers, this time, continue to drift outward until they leave the star. Perhaps the outer layers escape as a shell of gas. Or perhaps they drift off gradually ...
The most important questions to study for the exam
... 20. In the spectra of stars, absorption lines of hydrogen are produced when atoms are excited from /n/ = 2 to higher levels. If hydrogen absorption lines are very strong in the spectrum of a particular star, what does this tell us about the temperature of the gas at this star's surface? • Intermedi ...
... 20. In the spectra of stars, absorption lines of hydrogen are produced when atoms are excited from /n/ = 2 to higher levels. If hydrogen absorption lines are very strong in the spectrum of a particular star, what does this tell us about the temperature of the gas at this star's surface? • Intermedi ...
Lecture 12
... • Practically this is a very hard thing to measure, since it requires measuring the entire EM spectrum of a source, which is impossible with a single type detector. • Bolometric fluxes have to be inferred by knowledge of the physics producing the luminous source for which you have partial informatio ...
... • Practically this is a very hard thing to measure, since it requires measuring the entire EM spectrum of a source, which is impossible with a single type detector. • Bolometric fluxes have to be inferred by knowledge of the physics producing the luminous source for which you have partial informatio ...
Luminosity and brightness
... Luminosity and brightness Luminosity Luminosity is a measure of the total energy given output by a star at all wavelengths form gamma radiation to radio waves. For example the Sun gives out about 500 million million million MJ of energy every second so its luminosity is 500 million million million M ...
... Luminosity and brightness Luminosity Luminosity is a measure of the total energy given output by a star at all wavelengths form gamma radiation to radio waves. For example the Sun gives out about 500 million million million MJ of energy every second so its luminosity is 500 million million million M ...
MAGNITUDE AND COLOR SYSTEMS
... Calibration is more difficult the broader is the band. This is because of changes in the source SED and the weighting function within the band. Cf. equation (2) of Lecture 12. o For Vega, or any other A0 V type star, mi = mj = V for all i, j o The zero point of the system is defined by the SED of an ...
... Calibration is more difficult the broader is the band. This is because of changes in the source SED and the weighting function within the band. Cf. equation (2) of Lecture 12. o For Vega, or any other A0 V type star, mi = mj = V for all i, j o The zero point of the system is defined by the SED of an ...
11 Stellar Remnants - Journigan-wiki
... The Type I Supernova The nova process can repeat itself over and over again given that the dwarf does not accumulate too much material. If enough gas gathers to push the dwarf over the Chandrasekhar Limit, the star will collapse unto a Type I supernova. This rapid collapse will eventually cause the ...
... The Type I Supernova The nova process can repeat itself over and over again given that the dwarf does not accumulate too much material. If enough gas gathers to push the dwarf over the Chandrasekhar Limit, the star will collapse unto a Type I supernova. This rapid collapse will eventually cause the ...
OK, here is my thinking on the subject:
... The accuracy is very dependent on the granularity of our measurement. In equation (3) we will find that AV is about 1/8 the size of AVA , AVB , or AVC . That said, the parallax angular difference from start to finish of any measurement needs to be in the order of 800 pixels to result in a granularit ...
... The accuracy is very dependent on the granularity of our measurement. In equation (3) we will find that AV is about 1/8 the size of AVA , AVB , or AVC . That said, the parallax angular difference from start to finish of any measurement needs to be in the order of 800 pixels to result in a granularit ...
ASTRONOMY 130
... It is easier to locate a celestial object if some prominent constellation or asterism can be found and used as a reference point. Ursa Major (the Big Dipper) serves as a good reference point for the north circumpolar constellations. Locate the Big Dipper. Begin with the star at the tip of the handle ...
... It is easier to locate a celestial object if some prominent constellation or asterism can be found and used as a reference point. Ursa Major (the Big Dipper) serves as a good reference point for the north circumpolar constellations. Locate the Big Dipper. Begin with the star at the tip of the handle ...
relativistic time correction on movement of distant galaxies
... stars. Suppose there is a Sun like star of about 5 billion years old, then that star was formed at about 13.4+5=18.4 billion years ago. (In fact, present age of this star is to be multiplied by 1+z =1.98. So it is 5x1.98= 9.9 billion light years. But we have just received light from that galaxy and ...
... stars. Suppose there is a Sun like star of about 5 billion years old, then that star was formed at about 13.4+5=18.4 billion years ago. (In fact, present age of this star is to be multiplied by 1+z =1.98. So it is 5x1.98= 9.9 billion light years. But we have just received light from that galaxy and ...
Microlensing
... 1 system with ~0.7 Jup (2.3 AU), and ~0.3 Jup (4.6 AU) Several planets in “stock”… modeling underway. Indication : systems with multiple planets more common ? ~Earth mass planets on ~AU orbits to be discovered soon… ...
... 1 system with ~0.7 Jup (2.3 AU), and ~0.3 Jup (4.6 AU) Several planets in “stock”… modeling underway. Indication : systems with multiple planets more common ? ~Earth mass planets on ~AU orbits to be discovered soon… ...
AST 105 HW #1 Solution Week of August 24 , 2015
... east or west of the Prime Meridian, the meridian in Greenwich, England. The night sky changes with latitude, because it changes the portion of the celestial sphere that can be above your horizon at any time. ...
... east or west of the Prime Meridian, the meridian in Greenwich, England. The night sky changes with latitude, because it changes the portion of the celestial sphere that can be above your horizon at any time. ...
Finding Constellations From Orion
... Following the stars of Orion’s Belt backwards (from 3 to 1) points us to Sirius (SEER-e-us), the Dog Star. This is the brightest star in the sky, and is part of the constellation Canis Major, the Great Dog. Drawing a line from Bellatrix (bell-LAY-triks) through Betelgeuse points us to Procyon (PRO- ...
... Following the stars of Orion’s Belt backwards (from 3 to 1) points us to Sirius (SEER-e-us), the Dog Star. This is the brightest star in the sky, and is part of the constellation Canis Major, the Great Dog. Drawing a line from Bellatrix (bell-LAY-triks) through Betelgeuse points us to Procyon (PRO- ...
Theoretical Problem 3
... 5. The mass and radius of the smallest star. The result found in (4a) suggests that there could be stars of any mass as long as such a relationship is fulfilled; however, this is not true. The gas inside normal stars fusing hydrogen is known to behave approximately as an ideal gas. This means that d ...
... 5. The mass and radius of the smallest star. The result found in (4a) suggests that there could be stars of any mass as long as such a relationship is fulfilled; however, this is not true. The gas inside normal stars fusing hydrogen is known to behave approximately as an ideal gas. This means that d ...
2. Velocity dispersions of galaxies
... X-ray measurements of hot intracluster gas correspond closely to Zwicky's observations of mass-to-light ratios for large clusters of nearly 10 to 1. Many of the experiments of the Chandra X-ray Observatory use this technique to independently determine the mass of clusters. ...
... X-ray measurements of hot intracluster gas correspond closely to Zwicky's observations of mass-to-light ratios for large clusters of nearly 10 to 1. Many of the experiments of the Chandra X-ray Observatory use this technique to independently determine the mass of clusters. ...
Lecture 14
... sort of force stops contraction before the core temperature rises above 107 K. • Thermal pressure cannot stop contraction because the star is constantly losing thermal energy from its ...
... sort of force stops contraction before the core temperature rises above 107 K. • Thermal pressure cannot stop contraction because the star is constantly losing thermal energy from its ...
Grade Nine Planetarium script
... h) Cygnus is on the opposite side of Cepheus from Cassiopeia. If you start from the top of Cepheus’ pointy head and draw a line straight down through the middle of his neck (if he had one) and go along this line for another 1.5 fist widths, you come to Deneb, the bright star in Cygnus. 12) The previ ...
... h) Cygnus is on the opposite side of Cepheus from Cassiopeia. If you start from the top of Cepheus’ pointy head and draw a line straight down through the middle of his neck (if he had one) and go along this line for another 1.5 fist widths, you come to Deneb, the bright star in Cygnus. 12) The previ ...
Observational astronomy
Observational astronomy is a division of the astronomical science that is concerned with recording data, in contrast with theoretical astrophysics, which is mainly concerned with finding out the measurable implications of physical models. It is the practice of observing celestial objects by using telescopes and other astronomical apparatus.As a science, the study of astronomy is somewhat hindered in that direct experiments with the properties of the distant universe are not possible. However, this is partly compensated by the fact that astronomers have a vast number of visible examples of stellar phenomena that can be examined. This allows for observational data to be plotted on graphs, and general trends recorded. Nearby examples of specific phenomena, such as variable stars, can then be used to infer the behavior of more distant representatives. Those distant yardsticks can then be employed to measure other phenomena in that neighborhood, including the distance to a galaxy.Galileo Galilei turned a telescope to the heavens and recorded what he saw. Since that time, observational astronomy has made steady advances with each improvement in telescope technology.A traditional division of observational astronomy is given by the region of the electromagnetic spectrum observed: Optical astronomy is the part of astronomy that uses optical components (mirrors, lenses and solid-state detectors) to observe light from near infrared to near ultraviolet wavelengths. Visible-light astronomy (using wavelengths that can be detected with the eyes, about 400 - 700 nm) falls in the middle of this range. Infrared astronomy deals with the detection and analysis of infrared radiation (this typically refers to wavelengths longer than the detection limit of silicon solid-state detectors, about 1 μm wavelength). The most common tool is the reflecting telescope but with a detector sensitive to infrared wavelengths. Space telescopes are used at certain wavelengths where the atmosphere is opaque, or to eliminate noise (thermal radiation from the atmosphere). Radio astronomy detects radiation of millimetre to dekametre wavelength. The receivers are similar to those used in radio broadcast transmission but much more sensitive. See also Radio telescopes. High-energy astronomy includes X-ray astronomy, gamma-ray astronomy, and extreme UV astronomy, as well as studies of neutrinos and cosmic rays.Optical and radio astronomy can be performed with ground-based observatories, because the atmosphere is relatively transparent at the wavelengths being detected. Observatories are usually located at high altitudes so as to minimise the absorption and distortion caused by the Earth's atmosphere. Some wavelengths of infrared light are heavily absorbed by water vapor, so many infrared observatories are located in dry places at high altitude, or in space.The atmosphere is opaque at the wavelengths used by X-ray astronomy, gamma-ray astronomy, UV astronomy and (except for a few wavelength ""windows"") far infrared astronomy, so observations must be carried out mostly from balloons or space observatories. Powerful gamma rays can, however be detected by the large air showers they produce, and the study of cosmic rays is a rapidly expanding branch of astronomy.For much of the history of observational astronomy, almost all observation was performed in the visual spectrum with optical telescopes. While the Earth's atmosphere is relatively transparent in this portion of the electromagnetic spectrum, most telescope work is still dependent on seeing conditions and air transparency, and is generally restricted to the night time. The seeing conditions depend on the turbulence and thermal variations in the air. Locations that are frequently cloudy or suffer from atmospheric turbulence limit the resolution of observations. Likewise the presence of the full Moon can brighten up the sky with scattered light, hindering observation of faint objects.For observation purposes, the optimal location for an optical telescope is undoubtedly in outer space. There the telescope can make observations without being affected by the atmosphere. However, at present it remains costly to lift telescopes into orbit. Thus the next best locations are certain mountain peaks that have a high number of cloudless days and generally possess good atmospheric conditions (with good seeing conditions). The peaks of the islands of Mauna Kea, Hawaii and La Palma possess these properties, as to a lesser extent do inland sites such as Llano de Chajnantor, Paranal, Cerro Tololo and La Silla in Chile. These observatory locations have attracted an assemblage of powerful telescopes, totalling many billion US dollars of investment.The darkness of the night sky is an important factor in optical astronomy. With the size of cities and human populated areas ever expanding, the amount of artificial light at night has also increased. These artificial lights produce a diffuse background illumination that makes observation of faint astronomical features very difficult without special filters. In a few locations such as the state of Arizona and in the United Kingdom, this has led to campaigns for the reduction of light pollution. The use of hoods around street lights not only improves the amount of light directed toward the ground, but also helps reduce the light directed toward the sky.Atmospheric effects (astronomical seeing) can severely hinder the resolution of a telescope. Without some means of correcting for the blurring effect of the shifting atmosphere, telescopes larger than about 15–20 cm in aperture can not achieve their theoretical resolution at visible wavelengths. As a result, the primary benefit of using very large telescopes has been the improved light-gathering capability, allowing very faint magnitudes to be observed. However the resolution handicap has begun to be overcome by adaptive optics, speckle imaging and interferometric imaging, as well as the use of space telescopes.Astronomers have a number of observational tools that they can use to make measurements of the heavens. For objects that are relatively close to the Sun and Earth, direct and very precise position measurements can be made against a more distant (and thereby nearly stationary) background. Early observations of this nature were used to develop very precise orbital models of the various planets, and to determine their respective masses and gravitational perturbations. Such measurements led to the discovery of the planets Uranus, Neptune, and (indirectly) Pluto. They also resulted in an erroneous assumption of a fictional planet Vulcan within the orbit of Mercury (but the explanation of the precession of Mercury's orbit by Einstein is considered one of the triumphs of his general relativity theory).