An introduction to the HR diagram File
... large radius and high surface temperatures. This is what makes them highly luminous. • They are using up their hydrogen fuel tremendously quickly. So they are extremely short lived (c10 000 000 years) • These high mass stars finish their lives in massive supernova explosions • At the bottom right th ...
... large radius and high surface temperatures. This is what makes them highly luminous. • They are using up their hydrogen fuel tremendously quickly. So they are extremely short lived (c10 000 000 years) • These high mass stars finish their lives in massive supernova explosions • At the bottom right th ...
00 T Tauri Stars Have Extensive Coronae?
... If there is substantial disagreement between an observational result and its expectation from established theory, astronomers tend to speak of a "problem". One of those problems wh ich bothered optical and UV astronomers during the past years is the discrepancy of the observed ratio of the Lya and H ...
... If there is substantial disagreement between an observational result and its expectation from established theory, astronomers tend to speak of a "problem". One of those problems wh ich bothered optical and UV astronomers during the past years is the discrepancy of the observed ratio of the Lya and H ...
astronomy practice test ch 9
... 4. Binary (double) stars can be detected by a. being seen as two separate stars with a telescope. b. one star traveling a wiggly proper motion path across the sky. c. one star dimming abruptly as another passes in front of it. d. pairs of absorption lines seen in the spectrum of what appears to be o ...
... 4. Binary (double) stars can be detected by a. being seen as two separate stars with a telescope. b. one star traveling a wiggly proper motion path across the sky. c. one star dimming abruptly as another passes in front of it. d. pairs of absorption lines seen in the spectrum of what appears to be o ...
Small Wonders: Cygnus
... Three degrees almost directly east of Deneb, we come across one of the most photographed nebulae in the night sky. The North American Nebula is spectacular in long exposure photographs, and unlike many objects in the sky clearly resembles its namesake. Until recently tho, its been considered a chall ...
... Three degrees almost directly east of Deneb, we come across one of the most photographed nebulae in the night sky. The North American Nebula is spectacular in long exposure photographs, and unlike many objects in the sky clearly resembles its namesake. Until recently tho, its been considered a chall ...
Chapter 1 Telescopes 1.1 Lenses
... the diameter of the objective of a telescope, the greater the number of stars that can be seen. Planets and other astronomical objects in the solar system are magnified using a telescope (unlike stars which are point objects and are seen through telescopes as point images no matter how large the mag ...
... the diameter of the objective of a telescope, the greater the number of stars that can be seen. Planets and other astronomical objects in the solar system are magnified using a telescope (unlike stars which are point objects and are seen through telescopes as point images no matter how large the mag ...
Galaxies and the Universe bb
... Fate of the universe • Final fate depends on the average _______ of the universe • If the density is _____ than the critical density, then the universe would ________ • Current estimates point to _____ then the critical density and predict an _______________, or open, ...
... Fate of the universe • Final fate depends on the average _______ of the universe • If the density is _____ than the critical density, then the universe would ________ • Current estimates point to _____ then the critical density and predict an _______________, or open, ...
Planetarium Key Points
... Using a motionless sphere we can define a great circle, the horizon, and its poles, zenith and nadir 2. The daily motion of the sphere All the sky moves from Est to West around an axis that seems fixed on the sphere (for short periods of time as human life) The motion and the sphere define two ...
... Using a motionless sphere we can define a great circle, the horizon, and its poles, zenith and nadir 2. The daily motion of the sphere All the sky moves from Est to West around an axis that seems fixed on the sphere (for short periods of time as human life) The motion and the sphere define two ...
Lecture (Powerpoint)
... the mass of the Sun, or ~80 Jupiter masses) never ``turn on'' Central temperatures never get hot enough for nuclear burning to begin in earnest Nuclear burning is what powers the star through its life Star sits around as a brown dwarf – too big and hot to be a planet, too small and cold to be a real ...
... the mass of the Sun, or ~80 Jupiter masses) never ``turn on'' Central temperatures never get hot enough for nuclear burning to begin in earnest Nuclear burning is what powers the star through its life Star sits around as a brown dwarf – too big and hot to be a planet, too small and cold to be a real ...
Astronomical Motions I: The Night Sky
... difficult to convince yourself that the altitude of the pole star is equal to the latitude of the observer. Notice that in each diagram the observer’s horizon is shown; it is represented by a tangent plane to Earth’s surface at the point where the observer is standing. Objects below the observer’s h ...
... difficult to convince yourself that the altitude of the pole star is equal to the latitude of the observer. Notice that in each diagram the observer’s horizon is shown; it is represented by a tangent plane to Earth’s surface at the point where the observer is standing. Objects below the observer’s h ...
A report of the SEEDS Direct Imaging Survey
... □ SEEDS has explored the wide-orbit giant planets of the Solar system scale. As a systematic survey, SEEDS has been most successful in direct imaging of planets. □ From SEEDS, 3 direct imaging discovery of planets and boundary-mass-objects (GJ 504 b, κ And b, GJ 758 b) and 3 brown dwarfs detection i ...
... □ SEEDS has explored the wide-orbit giant planets of the Solar system scale. As a systematic survey, SEEDS has been most successful in direct imaging of planets. □ From SEEDS, 3 direct imaging discovery of planets and boundary-mass-objects (GJ 504 b, κ And b, GJ 758 b) and 3 brown dwarfs detection i ...
Winter 2014
... After this process ends, a star cluster is left behind. The Pleiades star cluster is close enough that we can see the brightest several stars by eye. Returning to Orion, we can follow the Belt down and to the left and find ourselves at the brightest star in Earth’s night sky, Sirius. Sirius is one o ...
... After this process ends, a star cluster is left behind. The Pleiades star cluster is close enough that we can see the brightest several stars by eye. Returning to Orion, we can follow the Belt down and to the left and find ourselves at the brightest star in Earth’s night sky, Sirius. Sirius is one o ...
1.2.43The stellar populations of the Milky Way
... Pop. II stars occupy the spheroid – the stellar halo and bulge – and turn out to be the oldest stars known, with ages in the range (12 to 15) × 1091yr. Conspicuous examples are globular-cluster stars. Little or no interstellar gas is still associated with Pop. II stars, which is consistent with star ...
... Pop. II stars occupy the spheroid – the stellar halo and bulge – and turn out to be the oldest stars known, with ages in the range (12 to 15) × 1091yr. Conspicuous examples are globular-cluster stars. Little or no interstellar gas is still associated with Pop. II stars, which is consistent with star ...
Parallax class activity (in MSword)
... on an imaginary line drawn from the center of the tape line, and perpendicular to the tape line. You will measure accurately the distance from the exact center of the tape line to the person standing at point 1 (distance X). You will not reveal this distance to team 2. Team 2: Start planning your st ...
... on an imaginary line drawn from the center of the tape line, and perpendicular to the tape line. You will measure accurately the distance from the exact center of the tape line to the person standing at point 1 (distance X). You will not reveal this distance to team 2. Team 2: Start planning your st ...
Astrometric Reference Frame Science
... tied to the optically astrometric determined positions of the stars in the binary. The system consists of a K1 III giant primary with MV = 4.15 and a companion that is unseen in both photometric and spectroscopic observations. The radio emission as measured with VLBI shows a double-lobed structure w ...
... tied to the optically astrometric determined positions of the stars in the binary. The system consists of a K1 III giant primary with MV = 4.15 and a companion that is unseen in both photometric and spectroscopic observations. The radio emission as measured with VLBI shows a double-lobed structure w ...
Anatomy of a Supernova - hrsbstaff.ednet.ns.ca
... (red, green, and dark blue, respectively) escape and add features to the spectrum. As we observe these deeper layers, dominant elements from the shallower layers are backiit and seen as absorption lines (here filled with colors indicating the layers in which they dominate). The changing pattern of e ...
... (red, green, and dark blue, respectively) escape and add features to the spectrum. As we observe these deeper layers, dominant elements from the shallower layers are backiit and seen as absorption lines (here filled with colors indicating the layers in which they dominate). The changing pattern of e ...
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).