T3-Cosmic Star Formation History
... pace. Multiwavelength imaging surveys with the Hubble (HST) and Spitzer space telescopes and ground-based facilities, together with spectroscopic follow-up with 8-m-class telescopes, have led to the discovery of galaxies with confirmed redshifts as large as z = 7.5 (Finkelstein et al. 2013) as well a ...
... pace. Multiwavelength imaging surveys with the Hubble (HST) and Spitzer space telescopes and ground-based facilities, together with spectroscopic follow-up with 8-m-class telescopes, have led to the discovery of galaxies with confirmed redshifts as large as z = 7.5 (Finkelstein et al. 2013) as well a ...
Using color photometry to separate transiting exoplanets from false
... limitations of the radial velocity technique. Of the 59 candidates that were identified during the 2001 campaign of OGLEIII, 7 were considered too faint for follow-up observation and only 6 of the remaining candidates had radial velocity variations less than a few km s−1 and no sign of secondary tra ...
... limitations of the radial velocity technique. Of the 59 candidates that were identified during the 2001 campaign of OGLEIII, 7 were considered too faint for follow-up observation and only 6 of the remaining candidates had radial velocity variations less than a few km s−1 and no sign of secondary tra ...
Wolf-Rayet Stars
... Figure 2: Illustration of how the ‘radius’ of the star varies with wavelength for the WC5 star HD 165763. The solid line shows the ‘radius’ at which the ‘continuum’ optical depth, τ , is 1/3, which occurs in the wind at all wavelengths. The broken line is identical except the electron scattering op ...
... Figure 2: Illustration of how the ‘radius’ of the star varies with wavelength for the WC5 star HD 165763. The solid line shows the ‘radius’ at which the ‘continuum’ optical depth, τ , is 1/3, which occurs in the wind at all wavelengths. The broken line is identical except the electron scattering op ...
Aries The Ram - Maverick`s E-portfolio
... The constellation of Aries has been home to many legends. Sumerians in Mesopotamia were enthralled by a bright star residing in the constellation of Aries known as Hamal. Sumerians believed that Hamal, which means the lamb, was one of the stars in the Scimitar. They believed that the Scimitar was a ...
... The constellation of Aries has been home to many legends. Sumerians in Mesopotamia were enthralled by a bright star residing in the constellation of Aries known as Hamal. Sumerians believed that Hamal, which means the lamb, was one of the stars in the Scimitar. They believed that the Scimitar was a ...
The formation of disc galaxies in high-resolution moving
... Many feedback implementations in current use are not robust to resolution changes and require ‘retuning’ of the free parameters of the model to obtain the same or a similar result when the resolution is changed – if at all possible. The differences can be as extreme as those reported in Okamoto et a ...
... Many feedback implementations in current use are not robust to resolution changes and require ‘retuning’ of the free parameters of the model to obtain the same or a similar result when the resolution is changed – if at all possible. The differences can be as extreme as those reported in Okamoto et a ...
Observationes Cometarvm Anni 1618
... Arago, the French mathematician and astronomer, mentioned that the head of the comet split into several parts during December, a phenomenon observed by Cysatus (Hind, 1852: 10; Lynn, 1889: 408) and also by Wendelin and Christoph Scheiner. It then appeared as a cluster of bright stars, each with its ...
... Arago, the French mathematician and astronomer, mentioned that the head of the comet split into several parts during December, a phenomenon observed by Cysatus (Hind, 1852: 10; Lynn, 1889: 408) and also by Wendelin and Christoph Scheiner. It then appeared as a cluster of bright stars, each with its ...
The Marine Sextant
... • A sextant is used to determine the sextant altitude (hs) of a celestial body. • First, we have to decide which stars to observe; this is done using a Rude Starfinder or other methods. • When making an observation, the star should look as shown in the next slide... ...
... • A sextant is used to determine the sextant altitude (hs) of a celestial body. • First, we have to decide which stars to observe; this is done using a Rude Starfinder or other methods. • When making an observation, the star should look as shown in the next slide... ...
SS_L1
... thermal (Kelvin) time the time required for a body to radiate its total heat energy Ekin tK ~ Ekin / L Ekin is related to Egrav by the Virial theorem Ekin = –(1/2) Egrav. But Egrav = –q GM2 / R, where q ~ unity, so that tK = q/2 GM2 / LR ~ 3 107 qM2/LR y where M, L and R are in solar units. The “Ke ...
... thermal (Kelvin) time the time required for a body to radiate its total heat energy Ekin tK ~ Ekin / L Ekin is related to Egrav by the Virial theorem Ekin = –(1/2) Egrav. But Egrav = –q GM2 / R, where q ~ unity, so that tK = q/2 GM2 / LR ~ 3 107 qM2/LR y where M, L and R are in solar units. The “Ke ...
infoBIT - Gift Lake School
... that arise from human needs. As you will discover in working through this unit, there are often many possible solutions to the same technological problem. To guide your reading as you study how science and technology interact and support each other, keep the following questions in mind: 1. How much ...
... that arise from human needs. As you will discover in working through this unit, there are often many possible solutions to the same technological problem. To guide your reading as you study how science and technology interact and support each other, keep the following questions in mind: 1. How much ...
Collisions and Encounters of Stellar Systems
... post-collision remnant might lose much of its orbital angular momentum, and then fall towards the bottom of the potential well of the whole system, thereby enhancing the cloud-collision and star-formation rates still further. We do not yet have a good understanding of this complex chain of events, b ...
... post-collision remnant might lose much of its orbital angular momentum, and then fall towards the bottom of the potential well of the whole system, thereby enhancing the cloud-collision and star-formation rates still further. We do not yet have a good understanding of this complex chain of events, b ...
WIMPs and MACHOs - Caltech Astronomy
... These detectors, then, are located deep underground, where the rock shields many of the background muons, and they also focus on ‘upward’ traveling muons, that are much more likely to have been created by neutrinos that have traveled through Earth and interacted in the rock just below the detector. ...
... These detectors, then, are located deep underground, where the rock shields many of the background muons, and they also focus on ‘upward’ traveling muons, that are much more likely to have been created by neutrinos that have traveled through Earth and interacted in the rock just below the detector. ...
Launch Tool - Science NetLinks
... express his description of the natural world. Even the mathematical language of calculus that Newton created to describe gravity could not do Einstein’s ideas justice. Luckily, there was a form of mathematics called non-Euclidean geometry that had been developed by G. F. B. Riemann, which helped Ein ...
... express his description of the natural world. Even the mathematical language of calculus that Newton created to describe gravity could not do Einstein’s ideas justice. Luckily, there was a form of mathematics called non-Euclidean geometry that had been developed by G. F. B. Riemann, which helped Ein ...
Article PDF - IOPscience
... irregular galaxy (SagDIG), which now places this object very close to the edge of the Local Group zerovelocity surface ; (3) more information on the evolutionary histories of some individual Local Group members ; and (4) improved distance determinations to, and luminosities for, a number of Local Gr ...
... irregular galaxy (SagDIG), which now places this object very close to the edge of the Local Group zerovelocity surface ; (3) more information on the evolutionary histories of some individual Local Group members ; and (4) improved distance determinations to, and luminosities for, a number of Local Gr ...
sections 19-22 instructor notes
... radial motions will be the vector sum of their orbital motion about the galactic centre and their random space motions, which typically average 15–20 km/s. If Θ0 is known, one can construct a relationship for Θ(R0 sin l) = vR(max) + Θ0 sin l for 270° < l < 90°. The relationship can be extrapolated t ...
... radial motions will be the vector sum of their orbital motion about the galactic centre and their random space motions, which typically average 15–20 km/s. If Θ0 is known, one can construct a relationship for Θ(R0 sin l) = vR(max) + Θ0 sin l for 270° < l < 90°. The relationship can be extrapolated t ...
March 2016 BRAS Addendum Newsletter
... Sirius (Alpha CMa), “scorching”, “the Dog Star”, mag. -1.46, 06 45 09.25 -16 42 47.3, is a blue-white binary star, and is also the brightest star in the night sky. The companion star, Sirius B (the Pup),is a white dwarf star with a magnitude of 8.4, and has an orbital period of 50 years and a separa ...
... Sirius (Alpha CMa), “scorching”, “the Dog Star”, mag. -1.46, 06 45 09.25 -16 42 47.3, is a blue-white binary star, and is also the brightest star in the night sky. The companion star, Sirius B (the Pup),is a white dwarf star with a magnitude of 8.4, and has an orbital period of 50 years and a separa ...
UNIT 2—THE BIG BANG
... of this, his ideas were accepted by Byzantine, Islamic and Europe scholars for more than 1,400 years. Ptolemy accepted Aristotle’s idea that the Sun and the planets revolve around a spherical Earth, a geocentric view. Ptolemy developed this idea through observation and in mathematical detail. In doi ...
... of this, his ideas were accepted by Byzantine, Islamic and Europe scholars for more than 1,400 years. Ptolemy accepted Aristotle’s idea that the Sun and the planets revolve around a spherical Earth, a geocentric view. Ptolemy developed this idea through observation and in mathematical detail. In doi ...
GammaRay Bursts, the Strongest Explosions in the Universe.
... Gamma‐ray bursts, GRBS, short and intense burst of low energy γ‐rays that arrive from random directions in the sky are possibly the most fascinating astronomical objects known today. GRBs are fascinating because they are the brightest objects in the sky corresponding t ...
... Gamma‐ray bursts, GRBS, short and intense burst of low energy γ‐rays that arrive from random directions in the sky are possibly the most fascinating astronomical objects known today. GRBs are fascinating because they are the brightest objects in the sky corresponding t ...
Big History`s approach to knowledge
... of this, his ideas were accepted by Byzantine, Islamic and Europe scholars for more than 1,400 years. Ptolemy accepted Aristotle’s idea that the Sun and the planets revolve around a spherical Earth, a geocentric view. Ptolemy developed this idea through observation and in mathematical detail. In doi ...
... of this, his ideas were accepted by Byzantine, Islamic and Europe scholars for more than 1,400 years. Ptolemy accepted Aristotle’s idea that the Sun and the planets revolve around a spherical Earth, a geocentric view. Ptolemy developed this idea through observation and in mathematical detail. In doi ...
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).