Spectroscopic Variability of Supergiant Star HD14134, B3Ia
... Fig. 4 and Fig. 5. It has been revealed that the variability of radial velocity, equivalent widths, depths and half-widths of Hβ line, as well as HeIλ5875.72Å and averaged CII (λ6578.05Å, λ6582.88Å) lines indicate repeating features. The changes of the radial velocities and spectral parameters of ...
... Fig. 4 and Fig. 5. It has been revealed that the variability of radial velocity, equivalent widths, depths and half-widths of Hβ line, as well as HeIλ5875.72Å and averaged CII (λ6578.05Å, λ6582.88Å) lines indicate repeating features. The changes of the radial velocities and spectral parameters of ...
Radiation transfer
... The basis of this assumption is that randomising collisions occur on a fast enough timescale (or, equivalently, in a small enough region) that the state variables can be considered constant. Such is clearly true in the depths of a star, but at some point this must break down as the surface is approa ...
... The basis of this assumption is that randomising collisions occur on a fast enough timescale (or, equivalently, in a small enough region) that the state variables can be considered constant. Such is clearly true in the depths of a star, but at some point this must break down as the surface is approa ...
Lecture 6
... Sources of radiation Most important type of radiation is blackbody radiation. This is radiation that is in thermal equilibrium with matter at some temperature T. Lab source of blackbody radiation: hot oven with a small hole which does not disturb thermal equilibrium inside: ...
... Sources of radiation Most important type of radiation is blackbody radiation. This is radiation that is in thermal equilibrium with matter at some temperature T. Lab source of blackbody radiation: hot oven with a small hole which does not disturb thermal equilibrium inside: ...
Stellar Evolution
... What happens when a star, fusing hydrogen into helium on the main sequence, exhausts the hydrogen in the core? • hydrogen burning stops, star loses energy • core contracts, and gets hotter • higher temperature allows new nuclear reactions to start that are very slow at the ~15 million K temperature ...
... What happens when a star, fusing hydrogen into helium on the main sequence, exhausts the hydrogen in the core? • hydrogen burning stops, star loses energy • core contracts, and gets hotter • higher temperature allows new nuclear reactions to start that are very slow at the ~15 million K temperature ...
Astronomy 328 Midterm Exam - Department of Physics and Astronomy
... The Hlines (=656.3 nm) from two stars in a binary system are observed to have Doppler shifts of 0.022 and 0.044 nm, respectively. The period of the system is 20yr. The eclipse minima are flat bottomed and 200 days long. It takes 10 hours from first contact to reach the eclipse minimum. a) What ar ...
... The Hlines (=656.3 nm) from two stars in a binary system are observed to have Doppler shifts of 0.022 and 0.044 nm, respectively. The period of the system is 20yr. The eclipse minima are flat bottomed and 200 days long. It takes 10 hours from first contact to reach the eclipse minimum. a) What ar ...
Chapter21
... 22. As matter accumulates rapidly on a white dwarf, the star becomes smaller and its core becomes hotter. When the core temperature reaches 10 billion K, carbon fusion begins. The energy released by carbon fusion triggers a series of nuclear reactions that blow the star apart. 23. X-ray bursts occur ...
... 22. As matter accumulates rapidly on a white dwarf, the star becomes smaller and its core becomes hotter. When the core temperature reaches 10 billion K, carbon fusion begins. The energy released by carbon fusion triggers a series of nuclear reactions that blow the star apart. 23. X-ray bursts occur ...
P10263v1.2 Lab 6 Text
... points, use a ruler and draw the best fit straight line that passes as close as possible (but not necessarily through) all six points. Label this line “M(Baade)”. (2) On the same graph, plot the six points from the table log P vs M (Kraft). Again, use the lower half of the graph since you’re plottin ...
... points, use a ruler and draw the best fit straight line that passes as close as possible (but not necessarily through) all six points. Label this line “M(Baade)”. (2) On the same graph, plot the six points from the table log P vs M (Kraft). Again, use the lower half of the graph since you’re plottin ...
FREE Sample Here
... A) It contains between 100 billion and 1 trillion stars. B) Our solar system is located very close to the center of the Milky Way Galaxy. C) The galaxy is about 100,000 light-years in diameter. D) One rotation of the galaxy takes about 200 million years. Answer: B 25) Which of the following correctl ...
... A) It contains between 100 billion and 1 trillion stars. B) Our solar system is located very close to the center of the Milky Way Galaxy. C) The galaxy is about 100,000 light-years in diameter. D) One rotation of the galaxy takes about 200 million years. Answer: B 25) Which of the following correctl ...
Search For Trans-Neptunian Objects Using COROT
... and can provide astronomers much valuable knowledge about their formation and dynamical evolution. The current understanding of their properties, however, such as the total mass, orbital parameters and the size distribution, is still far from complete. Here we will present a study of re-examination ...
... and can provide astronomers much valuable knowledge about their formation and dynamical evolution. The current understanding of their properties, however, such as the total mass, orbital parameters and the size distribution, is still far from complete. Here we will present a study of re-examination ...
The Starry Messenger
... large as when viewed with the naked eye. In this way one may learn with all the certainty of sense evidence that the moon is not robed in a smooth and polished surface but is in fact rough and uneven, covered everywhere, just like the earth’s surface, with huge prominences, deep valleys, and chasms. ...
... large as when viewed with the naked eye. In this way one may learn with all the certainty of sense evidence that the moon is not robed in a smooth and polished surface but is in fact rough and uneven, covered everywhere, just like the earth’s surface, with huge prominences, deep valleys, and chasms. ...
NexStar GT - Celestron
... of over 4,000 objects, including customized lists of all the best deep-sky objects, bright double stars and variable stars. No matter at what level you are starting out, the NexStar will unfold for you and your friends all the wonders of the Universe. ...
... of over 4,000 objects, including customized lists of all the best deep-sky objects, bright double stars and variable stars. No matter at what level you are starting out, the NexStar will unfold for you and your friends all the wonders of the Universe. ...
9/28/16 Wednesday Parallax Lab
... The parallax of the pencil depends on the distance the pencil is from you -- the closer the object, the larger the parallax. Thus, although it may have been hard to tell precisely, when the pencil was half the original distance from you, it had twice the parallax; when it was double the original dis ...
... The parallax of the pencil depends on the distance the pencil is from you -- the closer the object, the larger the parallax. Thus, although it may have been hard to tell precisely, when the pencil was half the original distance from you, it had twice the parallax; when it was double the original dis ...
October 30, 2006
... space instruments in regard to the extent and composition of the solar system and universe. Explain the “red-shift.” Compare absolute versus apparent star magnitude and their relation to stellar distance. Describe the structure and life-cycle of stars. Describe sun as a star type. Identify gravity a ...
... space instruments in regard to the extent and composition of the solar system and universe. Explain the “red-shift.” Compare absolute versus apparent star magnitude and their relation to stellar distance. Describe the structure and life-cycle of stars. Describe sun as a star type. Identify gravity a ...
VLT identifications in the Chandra/XMM
... obscuration fraction (ratio of type2/type-1 AGN) from 4:1 in the local universe to much larger covering fractions (10:1) at high redshifts (see also Fabian et al., 1998). The gas to dust ratio in high-redshift, high-luminosity AGN could be completely different from the usually assumed galactic value ...
... obscuration fraction (ratio of type2/type-1 AGN) from 4:1 in the local universe to much larger covering fractions (10:1) at high redshifts (see also Fabian et al., 1998). The gas to dust ratio in high-redshift, high-luminosity AGN could be completely different from the usually assumed galactic value ...
FROM MOLECULAR CLOUDS TO STARS 1 Star formation and the
... clouds. CO is the best tracer of the diffuse medium because it is very abundant ([CO]/[ H2], ~ 10-4), it has a relatively high dissociation energy (11.09 eV) and it can be excited from millimetre wavelengths (few Kelvin) to the near infrared (~ 3000 K) in a variety of different physical environments ...
... clouds. CO is the best tracer of the diffuse medium because it is very abundant ([CO]/[ H2], ~ 10-4), it has a relatively high dissociation energy (11.09 eV) and it can be excited from millimetre wavelengths (few Kelvin) to the near infrared (~ 3000 K) in a variety of different physical environments ...
The Kuiper Belt Explored by Serendipitous Stellar Occultations
... decay δF = [r/(αD)]2, where D is the object-to-Earth distance (for an impact parameter smaller than αD – r). αD = R* is the radius of the star projected at the distance of the occulting object. Note that if the star’s apparent size is known, the occultation profile provides some information on the o ...
... decay δF = [r/(αD)]2, where D is the object-to-Earth distance (for an impact parameter smaller than αD – r). αD = R* is the radius of the star projected at the distance of the occulting object. Note that if the star’s apparent size is known, the occultation profile provides some information on the o ...
Stars
... The distance of a star when it appears to shift one second of a degree due to parallax. 1 pc = 3.26 ly. ...
... The distance of a star when it appears to shift one second of a degree due to parallax. 1 pc = 3.26 ly. ...
Atmospheric biomarkers on terrestrial exoplanets Abstract Introduction
... ozone destruction, directly by photolysis, but mostly indirectly due to the increased photochemical production of highly reactive radicals. For atmospheric compositions similar to the Earth’s, numerical simulations show a quantity of O increasing with the UV flux (Selsis, 2000). This property could ...
... ozone destruction, directly by photolysis, but mostly indirectly due to the increased photochemical production of highly reactive radicals. For atmospheric compositions similar to the Earth’s, numerical simulations show a quantity of O increasing with the UV flux (Selsis, 2000). This property could ...
HR Diagram of Messier 80 using Hubble Space Telescope Data
... (4) Is the F450W a “red”, “green” or “blue” filter, meaning what color would things be if you looked through the filter at something? (5) Is the F814W a “red”, “green” or “blue” filter? (6) Is there any overlap to the filters? (7) How many other filters does the Hubble Space Telescope use? (8) Name ...
... (4) Is the F450W a “red”, “green” or “blue” filter, meaning what color would things be if you looked through the filter at something? (5) Is the F814W a “red”, “green” or “blue” filter? (6) Is there any overlap to the filters? (7) How many other filters does the Hubble Space Telescope use? (8) Name ...
astro-ph/0504597 PDF
... their occurance and schedule the observing time at the world’s largest telescopes in advance. More over they are fleeting and must be observed carefully multiple times within the first few weeks, if they are discovered after passing the peak brightness, that will be of little use as the peak brightn ...
... their occurance and schedule the observing time at the world’s largest telescopes in advance. More over they are fleeting and must be observed carefully multiple times within the first few weeks, if they are discovered after passing the peak brightness, that will be of little use as the peak brightn ...
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).