Barium and europium abundances in cool dwarf stars and
... Galactic interstellar gas. Overabundances of α-elements relative to iron observed in old stars argue in favour of this model (see the review of McWilliam 1997). Another argument can be obtained from observations of the heavy elements beyond the iron group. Abundances of these elements in the solar s ...
... Galactic interstellar gas. Overabundances of α-elements relative to iron observed in old stars argue in favour of this model (see the review of McWilliam 1997). Another argument can be obtained from observations of the heavy elements beyond the iron group. Abundances of these elements in the solar s ...
Chemical composition of 90 F and G disk dwarfs
... α elements; [Mg/Fe] and [Ti/Fe] show a larger scatter at a given metallicity than [Si/Fe] and [Ca/Fe]. It suggests that individual α elements may have different origins. (6) A new stellar group, rich in Na, Mg, Al, was found among the metal-rich disk stars, suggesting additional synthesis sources fo ...
... α elements; [Mg/Fe] and [Ti/Fe] show a larger scatter at a given metallicity than [Si/Fe] and [Ca/Fe]. It suggests that individual α elements may have different origins. (6) A new stellar group, rich in Na, Mg, Al, was found among the metal-rich disk stars, suggesting additional synthesis sources fo ...
The physics and modes of star cluster formation: observations
... infrared wavelengths (e.g. Green & Lada 1996; White et al. 2007). Infrared spectroscopic surveys, especially those done with multi-object spectrographs, can be used to identify accreting objects in a cluster field. However, such observations can be time-consuming and even prohibitive for faint member ...
... infrared wavelengths (e.g. Green & Lada 1996; White et al. 2007). Infrared spectroscopic surveys, especially those done with multi-object spectrographs, can be used to identify accreting objects in a cluster field. However, such observations can be time-consuming and even prohibitive for faint member ...
Chapter 17--Star Stuff
... potassium ions moderate communications of the nervous system. What does all this biology have to do with astronomy? The profound answer, recognized only in the second half of the twentieth century, is that life is based on elements created by stars. We’ve already discussed in general terms how the e ...
... potassium ions moderate communications of the nervous system. What does all this biology have to do with astronomy? The profound answer, recognized only in the second half of the twentieth century, is that life is based on elements created by stars. We’ve already discussed in general terms how the e ...
Hunting for Substructure in the Milky Way
... of the star. Astronomers can gain information about a star from its absorption spectrum. Light from the star passes through the star’s atmosphere and absorption lines in the spectrum indicate which elements are present in the atmosphere. These are therefore the elements which were present in the gal ...
... of the star. Astronomers can gain information about a star from its absorption spectrum. Light from the star passes through the star’s atmosphere and absorption lines in the spectrum indicate which elements are present in the atmosphere. These are therefore the elements which were present in the gal ...
Worlds Beyond: A Strategy for the Detection and Characterization of
... technology development across different wavelengths and techniques. Once Earth-mass planets are known to orbit nearby sun-like stars, the Task Force recommends launching a direct imaging space mission for habitability characterization. The hierarchy of pressing questions in the search for Earth anal ...
... technology development across different wavelengths and techniques. Once Earth-mass planets are known to orbit nearby sun-like stars, the Task Force recommends launching a direct imaging space mission for habitability characterization. The hierarchy of pressing questions in the search for Earth anal ...
The Sun as a star: observations of white-light flares - HAL-Insu
... flare. Furthermore, many flares were observed with no associated white-light emission and with no means to determine if this was because of instrumental limitations or because of the actual absence of WL emission. Recent studies (Jess et al. 2008; Wang 2009) identified WL emission in relatively smal ...
... flare. Furthermore, many flares were observed with no associated white-light emission and with no means to determine if this was because of instrumental limitations or because of the actual absence of WL emission. Recent studies (Jess et al. 2008; Wang 2009) identified WL emission in relatively smal ...
thick disk - asteroSTEP
... Look at the HR1614 group (age ~ 2 Gyr, [Fe/H] = +0.2) which appears to be a relic of a dispersed star forming event. Its stars are scattered all around us. This group has not lost its dynamical identity despite its age. De Silva et al (2007) measured accurate differential abundances for many elemen ...
... Look at the HR1614 group (age ~ 2 Gyr, [Fe/H] = +0.2) which appears to be a relic of a dispersed star forming event. Its stars are scattered all around us. This group has not lost its dynamical identity despite its age. De Silva et al (2007) measured accurate differential abundances for many elemen ...
bode elert johann
... to be double22). He had an appropriate reflector about this time, for on 15 May 1778 he notes: “I tried the speculum last night on Saturn and found it to act very well with 3 and 4 inches of aperture.”23 17 August 1779 marks Herschel’s actual turn to stellar astronomy, inspired by the question of pa ...
... to be double22). He had an appropriate reflector about this time, for on 15 May 1778 he notes: “I tried the speculum last night on Saturn and found it to act very well with 3 and 4 inches of aperture.”23 17 August 1779 marks Herschel’s actual turn to stellar astronomy, inspired by the question of pa ...
A S T R O N O M Y 1 1 0 - the Home Page for Voyager2.DVC.edu.
... Solutions in algebra are not very intuitive. Don’t expect to know the answer automatically, no matter how brilliant you are. It is rather like fixing a car or cooking. No matter how smart you are, it still takes all the steps and a bunch of time. It doesn’t mean that you are dumb or bad at math. It ...
... Solutions in algebra are not very intuitive. Don’t expect to know the answer automatically, no matter how brilliant you are. It is rather like fixing a car or cooking. No matter how smart you are, it still takes all the steps and a bunch of time. It doesn’t mean that you are dumb or bad at math. It ...
Carl Sagan - Cosmos (1980) [Full Color Illustrated
... people, or 3 percent of the human population of the planet Earth. It is dedicated to the proposition that the public is far more intelligent than it has generally been given credit for; that the deepest scientific questions on the nature and origin of the world excite the interests and passions of e ...
... people, or 3 percent of the human population of the planet Earth. It is dedicated to the proposition that the public is far more intelligent than it has generally been given credit for; that the deepest scientific questions on the nature and origin of the world excite the interests and passions of e ...
Angular Momentum Evolution of Young Low
... at multiple ages and in different star-forming environments that are essential for testing theory. In parallel, substantial theoretical developments have been carried out in the last few years, including the physics of the star-disk interaction, numerical simulations of stellar winds, and the invest ...
... at multiple ages and in different star-forming environments that are essential for testing theory. In parallel, substantial theoretical developments have been carried out in the last few years, including the physics of the star-disk interaction, numerical simulations of stellar winds, and the invest ...
Astronomy Assignment #1
... The points where the celestial equator intersect the horizon are 90° azimuth (due East) and 270° azimuth (due West) for all observers independent of their latitude. An observer in the northern hemisphere will see the celestial equator cross the local meridian looking south, while an observer in the ...
... The points where the celestial equator intersect the horizon are 90° azimuth (due East) and 270° azimuth (due West) for all observers independent of their latitude. An observer in the northern hemisphere will see the celestial equator cross the local meridian looking south, while an observer in the ...
Luminosities and mass-loss rates of SMC and LMC AGB stars and
... interstellar medium, AGB stars are key players in the life cycle of dust and gas in the universe. However, a quantitative understanding of the mass-loss process is still largely lacking, particularly its dependence on metallicity. Aims. To investigate the relation between mass loss, luminosity and p ...
... interstellar medium, AGB stars are key players in the life cycle of dust and gas in the universe. However, a quantitative understanding of the mass-loss process is still largely lacking, particularly its dependence on metallicity. Aims. To investigate the relation between mass loss, luminosity and p ...
High-mass star-forming cloud G0.38+0.04 in the Galactic center dust
... the observations is typically 0.400 but no worse than 1.000 , based on previous ATCA observations (Caswell 2009). ...
... the observations is typically 0.400 but no worse than 1.000 , based on previous ATCA observations (Caswell 2009). ...
Astronomy Astrophysics - Niels Bohr Institutet
... attention has been given to a realistic treatment of statistical biases and error estimates, as standard techniques tend to underestimate these effects and introduce spurious features in the age distributions. Our ages agree well with those by Edvardsson et al. (1993), despite several astrophysical a ...
... attention has been given to a realistic treatment of statistical biases and error estimates, as standard techniques tend to underestimate these effects and introduce spurious features in the age distributions. Our ages agree well with those by Edvardsson et al. (1993), despite several astrophysical a ...
Stellarium User Guide
... scipting facility is Stellarium’s version of a “Presentation”, a feature that may be used to run an astronomical or other presentation for instruction or entertainment from within the Stellarium program. The original Stratoscript was quite limited in what it could do so a new Stellarium Scripting Sy ...
... scipting facility is Stellarium’s version of a “Presentation”, a feature that may be used to run an astronomical or other presentation for instruction or entertainment from within the Stellarium program. The original Stratoscript was quite limited in what it could do so a new Stellarium Scripting Sy ...
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).