The spectroscopic Hertzsprung
... the g − T eff diagrams. In contrast to the last two, the sHR diagram has an impenetrable upper limit, i.e., the Eddington limit. For example, since for large mass the mass-luminosity exponent α in the mass luminosity relation L ∼ M α tends asymptotically to α = 1 (Kippenhahn & Weigert 1990), even st ...
... the g − T eff diagrams. In contrast to the last two, the sHR diagram has an impenetrable upper limit, i.e., the Eddington limit. For example, since for large mass the mass-luminosity exponent α in the mass luminosity relation L ∼ M α tends asymptotically to α = 1 (Kippenhahn & Weigert 1990), even st ...
Ages of Young Stars
... These results show that LDB age uncertainties have yet to attain the floor set by levels of theoretical understanding. There is scope for improvement, particularly in defining the position of the LDB, photometric calibration of cool stars and better estimates of cluster distances. The LDB technique ...
... These results show that LDB age uncertainties have yet to attain the floor set by levels of theoretical understanding. There is scope for improvement, particularly in defining the position of the LDB, photometric calibration of cool stars and better estimates of cluster distances. The LDB technique ...
Earth_Science_Notebook_January_2011
... Warm ups are done individually and quietly in your desk. Warm up time is usually 5-7 minutes and is a time for you to get prepared and focused for class. Write your name, today’s date, and Earth Science on the paper that you have received. -Answer the following prompt: Write a 5 sentence paragraph a ...
... Warm ups are done individually and quietly in your desk. Warm up time is usually 5-7 minutes and is a time for you to get prepared and focused for class. Write your name, today’s date, and Earth Science on the paper that you have received. -Answer the following prompt: Write a 5 sentence paragraph a ...
The white dwarf population within 40 pc of the Sun
... smaller than ∼ 10 M⊙ will end their lives as white dwarfs (Garcı́a-Berro et al. 1997; Poelarends et al. 2008). Hence, given the shape of the initial mass function, the local population of white dwarfs carries crucial information about the physical processes governing the evolution of the vast majori ...
... smaller than ∼ 10 M⊙ will end their lives as white dwarfs (Garcı́a-Berro et al. 1997; Poelarends et al. 2008). Hence, given the shape of the initial mass function, the local population of white dwarfs carries crucial information about the physical processes governing the evolution of the vast majori ...
new horizons pluto approach navigation
... and semi-major axis of the orbit. The period can be measured to high precision from Earth based telescope observations and the orbit diameter can be measured to a precision of perhaps 100 km enabling the system mass to be determined within 1 percent. The maximum separation of Pluto and Charon on a s ...
... and semi-major axis of the orbit. The period can be measured to high precision from Earth based telescope observations and the orbit diameter can be measured to a precision of perhaps 100 km enabling the system mass to be determined within 1 percent. The maximum separation of Pluto and Charon on a s ...
Astronomy Astrophysics Gaia-ESO Survey: The analysis of high-resolution The
... Obtaining the spectroscopic data to achieve this goal is demanding. To determine accurate, detailed elemental abundances, we need high-resolution, high signal-to-noise (S/N) spectra with broad wavelength coverage. For robust statistics and to cover all Galactic populations, the observation of large ...
... Obtaining the spectroscopic data to achieve this goal is demanding. To determine accurate, detailed elemental abundances, we need high-resolution, high signal-to-noise (S/N) spectra with broad wavelength coverage. For robust statistics and to cover all Galactic populations, the observation of large ...
Properties of White Dwarfs, Teacher Guide
... relative to our Sun. There are two motions that can be measured: radial velocity (in the line of sight) measured through spectroscopy and tangential velocity (perpendicular to the line of sight). Tangential velocity is obtained from knowing the star's distance and “proper motion” (motion across the ...
... relative to our Sun. There are two motions that can be measured: radial velocity (in the line of sight) measured through spectroscopy and tangential velocity (perpendicular to the line of sight). Tangential velocity is obtained from knowing the star's distance and “proper motion” (motion across the ...
Star formation rates and efficiencies in the Galactic Centre
... when applied to the CMZ compared to other environments. Star formation rates within local clouds are primarily determined by counting the embedded young-stellar population (YSO counting; refer to section 3.2.1). However, it is not possible to use this technique in external galaxies, as the individua ...
... when applied to the CMZ compared to other environments. Star formation rates within local clouds are primarily determined by counting the embedded young-stellar population (YSO counting; refer to section 3.2.1). However, it is not possible to use this technique in external galaxies, as the individua ...
Comprehensive Wide-Band Magnitudes and Albedos for the Planets
... (1961), de Vaucouleurs (1964) and Irvine et al. (1968) are especially notable. Furthermore, Lockwood, ...
... (1961), de Vaucouleurs (1964) and Irvine et al. (1968) are especially notable. Furthermore, Lockwood, ...
Gaia 1 and 2. A pair of new satellites of the Galaxy
... The cut at faint magnitudes G < 21 is less straightforward. Usually, when dealing with large optical ground-based surveys, it is advisable to restrict the data to be limited by the apparent magnitude which gives the most uniform density map. However, in our case, due to the relatively shallow Gaia D ...
... The cut at faint magnitudes G < 21 is less straightforward. Usually, when dealing with large optical ground-based surveys, it is advisable to restrict the data to be limited by the apparent magnitude which gives the most uniform density map. However, in our case, due to the relatively shallow Gaia D ...
Annual Report 2011 - Max Planck Institute for Astrophysics
... development of a distributed processing system to be used as the backbone both for simulation of the mission and later for the data analysis itself. The mission simulation package was mainly developed at MPA and is still maintained here. MPA directly supports the operation of the Trieste data centre ...
... development of a distributed processing system to be used as the backbone both for simulation of the mission and later for the data analysis itself. The mission simulation package was mainly developed at MPA and is still maintained here. MPA directly supports the operation of the Trieste data centre ...
Neutron Stars
... with Prof. Antony Hewish at Cambridge. Pulsars derive their name from ”pulsating radio sources” because they were first observed at radio wave frequencies. Hewish won the 1974 Nobel Prize in Physics along with Sir Martin Ryle for their ”pioneering discoveries in radio astrophysics.” Hewish was cited ...
... with Prof. Antony Hewish at Cambridge. Pulsars derive their name from ”pulsating radio sources” because they were first observed at radio wave frequencies. Hewish won the 1974 Nobel Prize in Physics along with Sir Martin Ryle for their ”pioneering discoveries in radio astrophysics.” Hewish was cited ...
On the Spiral Structure of the Milky Way Galaxy
... latter objects can currently be determined very precisely but only for those of them that are within 3—4 kpc from the Sun. During the most recent years, direct data have begun to accumulate on larger distances for sources of maser emission (related to young stars); they were obtained by means of ver ...
... latter objects can currently be determined very precisely but only for those of them that are within 3—4 kpc from the Sun. During the most recent years, direct data have begun to accumulate on larger distances for sources of maser emission (related to young stars); they were obtained by means of ver ...
UvA-DARE (Digital Academic Repository)
... This raises intriguing questions: if the Sun is not special, then how special is the Earth that we live on, and how special are we? Do all stars we see have planets, and what do these look like? Are any of these planets able to support life, and is there intelligent life out there? We are now starti ...
... This raises intriguing questions: if the Sun is not special, then how special is the Earth that we live on, and how special are we? Do all stars we see have planets, and what do these look like? Are any of these planets able to support life, and is there intelligent life out there? We are now starti ...
An X-Ray, Optical and Infra-red study of High-Mass X
... is continually growing and is now a similar size to that of the Milky Way, despite a significant mass difference between the two galaxies. In this thesis, I present multi-wavelength observations of Be/X-ray binaries that have undergone an outburst during the past three years, including the discovery ...
... is continually growing and is now a similar size to that of the Milky Way, despite a significant mass difference between the two galaxies. In this thesis, I present multi-wavelength observations of Be/X-ray binaries that have undergone an outburst during the past three years, including the discovery ...
ROSAT Ian R. Stevens* and David K. Strickland*
... difficult even with high signal-to-noise ratio (S/N) data. This does mean that our sample of WR galaxies will tend to be rather heterogenous. Future studies will have to focus on broader samples of starburst galaxies and starburst regions such as 30 Dor. Of the additional 40 WR galaxies in the enlar ...
... difficult even with high signal-to-noise ratio (S/N) data. This does mean that our sample of WR galaxies will tend to be rather heterogenous. Future studies will have to focus on broader samples of starburst galaxies and starburst regions such as 30 Dor. Of the additional 40 WR galaxies in the enlar ...
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).