PHYS3380_110215_bw - The University of Texas at Dallas
... •In stars of less than about 10 solar masses, the outer envelope of the star contains a region where partial ionization of hydrogen and helium raises the heat capacity. The relatively low temperature in this region simultaneously causes the opacity due to heavier elements to be high enough to produc ...
... •In stars of less than about 10 solar masses, the outer envelope of the star contains a region where partial ionization of hydrogen and helium raises the heat capacity. The relatively low temperature in this region simultaneously causes the opacity due to heavier elements to be high enough to produc ...
Leverhulme lectures on stellar magnetism. 1. Overview
... field along line of sight, right is for field transverse to sight line Top row: splitting of some typical line in lab 2nd row: effects on unpolarised absorption line – little change in shape 3rd row: spectral line as seen in left & right or parallel & perpendicular polarisation ...
... field along line of sight, right is for field transverse to sight line Top row: splitting of some typical line in lab 2nd row: effects on unpolarised absorption line – little change in shape 3rd row: spectral line as seen in left & right or parallel & perpendicular polarisation ...
Astronomy 112: The Physics of Stars Class 19 Notes: The Stellar
... is important for very old clusters: the luminosity of red giants. Although there aren’t many such stars present in any given cluster at a given time due to the short times that stars spend as red giants, they are so bright that they can dominate the total luminosity once the massive stars have faded ...
... is important for very old clusters: the luminosity of red giants. Although there aren’t many such stars present in any given cluster at a given time due to the short times that stars spend as red giants, they are so bright that they can dominate the total luminosity once the massive stars have faded ...
Modified True/False - Indicate whether the statement is true or false
... ____ 16. HS-ESS1-1 The process in which smaller atomic nuclei combine into larger atomic nuclei is known as a. Gravitational attraction. c. The Doppler effect. b. Parallax. d. Nuclear fusion. ____ 17. HS-ESS1-2 The apparent shift in a star’s position caused by the motion of the observer is called __ ...
... ____ 16. HS-ESS1-1 The process in which smaller atomic nuclei combine into larger atomic nuclei is known as a. Gravitational attraction. c. The Doppler effect. b. Parallax. d. Nuclear fusion. ____ 17. HS-ESS1-2 The apparent shift in a star’s position caused by the motion of the observer is called __ ...
Searching for the oldest, most metal-poor stars in the SkyMapper Survey
... the strength of the calcium absorption line. Measuring the difference between the stellar flux in the different filters (e.g. g − r) yields colors for each star. Detailed combination of colors involving the v filter and other colors enables the selection of low-metallicity candidates. The candidate ...
... the strength of the calcium absorption line. Measuring the difference between the stellar flux in the different filters (e.g. g − r) yields colors for each star. Detailed combination of colors involving the v filter and other colors enables the selection of low-metallicity candidates. The candidate ...
X-ray Emission from Massive Stars
... X-rays from shock-heating in linedriven winds The Doppler desaturation that’s so helpful in driving a flow via momentum transfer in spectral lines is inherently unstable The line-driven instability (LDI) arises when a parcel of wind material is accelerated above the local flow speed, which moves it ...
... X-rays from shock-heating in linedriven winds The Doppler desaturation that’s so helpful in driving a flow via momentum transfer in spectral lines is inherently unstable The line-driven instability (LDI) arises when a parcel of wind material is accelerated above the local flow speed, which moves it ...
Journey to the Stars Educator`s Guide
... 5. Our Solar Neighborhood • The stellar life cycle continues today. Stars still form, live, and die. The young Orion Nebula contains one of many clusters of newborn stars in the Milky Way. Some of them are just forming planets. The Pleiades, a mature star cluster, is ejecting stars. The Helix Nebula ...
... 5. Our Solar Neighborhood • The stellar life cycle continues today. Stars still form, live, and die. The young Orion Nebula contains one of many clusters of newborn stars in the Milky Way. Some of them are just forming planets. The Pleiades, a mature star cluster, is ejecting stars. The Helix Nebula ...
ASTRONOMY AND ASTROPHYSICS Barium abundances in cool
... (1990) who compiled the results of 6 analyses. In both compilations the systematic differences from author-to-author are evident. For example, [Ba/Fe] of Leep & Wallerstein (1981) or Gilroy et al. (1988) is lower on average by 0.5 dex than the results of Magain (1989) or Peterson et al. (1990). Such ...
... (1990) who compiled the results of 6 analyses. In both compilations the systematic differences from author-to-author are evident. For example, [Ba/Fe] of Leep & Wallerstein (1981) or Gilroy et al. (1988) is lower on average by 0.5 dex than the results of Magain (1989) or Peterson et al. (1990). Such ...
Chromospherically young, kinematically old stars
... interpreted as a sign of its youth. Young dwarfs show high rotation rates, and the interaction between rotation and outer envelope convection is expected to drive the chromospheric activity. Nevertheless, not only young single stars present high rotation rates. Close and contact binaries can keep hi ...
... interpreted as a sign of its youth. Young dwarfs show high rotation rates, and the interaction between rotation and outer envelope convection is expected to drive the chromospheric activity. Nevertheless, not only young single stars present high rotation rates. Close and contact binaries can keep hi ...
A billion pixels, a billion stars
... a planet passes between us and its parent star) or kinematically (by measuring the change in the parent star’s velocity along our line of sight due to the reflex motion induced by the planet). Because Gaia makes highly accurate measurements of stars’ reflex motion in 2D, it is a very sensitive kinem ...
... a planet passes between us and its parent star) or kinematically (by measuring the change in the parent star’s velocity along our line of sight due to the reflex motion induced by the planet). Because Gaia makes highly accurate measurements of stars’ reflex motion in 2D, it is a very sensitive kinem ...
Stellar Evolution – Cosmic Cycles of Formation and Destruction
... All main sequence stars with a mass less than ~8 solar masses are sometimes referred to as dwarf stars, with the coolest, least massive stars in the lower right corner called red dwarfs. The more massive the star, the faster the rate of fusion, and the less time it remains on the main sequence. The ...
... All main sequence stars with a mass less than ~8 solar masses are sometimes referred to as dwarf stars, with the coolest, least massive stars in the lower right corner called red dwarfs. The more massive the star, the faster the rate of fusion, and the less time it remains on the main sequence. The ...
PSF - ESO
... DAOPHOT fits multiple stars with partially overlapping profiles (distances smaller than 1 PSF radius+1fitting radius). An improvement of the original program is in ALLSTAR, which performs the simultaneous determination of position and brightness estimate for every star in a digital image. In other w ...
... DAOPHOT fits multiple stars with partially overlapping profiles (distances smaller than 1 PSF radius+1fitting radius). An improvement of the original program is in ALLSTAR, which performs the simultaneous determination of position and brightness estimate for every star in a digital image. In other w ...
Article “What Astronomers Do” (appendix C) one per student
... Italian astronomer and Catholic priest, Father Pietro Angelo Secchi, developed a classification scheme for stellar spectra which used the Roman numerals I to V to describe the relative strength of the various absorption lines which were visible. His sequence went from the blue end of the spectrum to ...
... Italian astronomer and Catholic priest, Father Pietro Angelo Secchi, developed a classification scheme for stellar spectra which used the Roman numerals I to V to describe the relative strength of the various absorption lines which were visible. His sequence went from the blue end of the spectrum to ...
Stellar Physics
... For electromagnetic radiation, flux is defined as the rate of flow of energy passing through unit area. (Or average power per unit area.) For visible light this is called brightness and is in effect the apparent brightness at the surface of the star. From the Stefan-Boltzmann law for a black-body: F ...
... For electromagnetic radiation, flux is defined as the rate of flow of energy passing through unit area. (Or average power per unit area.) For visible light this is called brightness and is in effect the apparent brightness at the surface of the star. From the Stefan-Boltzmann law for a black-body: F ...
the solar neighborhood. xi. the trigonometric parallax of scr
... These reference stars were used to fit linear models for each of the plates with respect to the array of mean reference star positions. The residual errors from the reference stars after these models are applied give an indication of the astrometric quality of each plate; as a result of this test, o ...
... These reference stars were used to fit linear models for each of the plates with respect to the array of mean reference star positions. The residual errors from the reference stars after these models are applied give an indication of the astrometric quality of each plate; as a result of this test, o ...
PDF format
... They are located only near the center of the galaxy. Their stars are among the oldest in the universe. They are located only in the disk of the galaxy. Their stars are among the youngest in the universe. B and C ...
... They are located only near the center of the galaxy. Their stars are among the oldest in the universe. They are located only in the disk of the galaxy. Their stars are among the youngest in the universe. B and C ...
s-process
... Significant production of r-process elements began when the metallicity of the Galaxy reached [Fe/H] = -3. The heavy n-capture elements were formed predominantly by the r-process at metallicities below [Fe/H] = -2.1. Elements from the s-process appear at a metallicity of [Fe/H] = -2.1, when low-mass ...
... Significant production of r-process elements began when the metallicity of the Galaxy reached [Fe/H] = -3. The heavy n-capture elements were formed predominantly by the r-process at metallicities below [Fe/H] = -2.1. Elements from the s-process appear at a metallicity of [Fe/H] = -2.1, when low-mass ...
Publications 2003 - Département d`Astrophysique, Géophysique et
... eccentric orbit (e=0.81) and similar component masses with a mass ratio M1/M2=1.02. Cen forms a challenge for current evolution scenarios in close binaries and it is also a puzzle how a massive binary with such a large eccentricity could have formed in the first place. Both the primary and the seco ...
... eccentric orbit (e=0.81) and similar component masses with a mass ratio M1/M2=1.02. Cen forms a challenge for current evolution scenarios in close binaries and it is also a puzzle how a massive binary with such a large eccentricity could have formed in the first place. Both the primary and the seco ...
color magnitude diagrams - AST 114, Astronomy Lab II for Spring
... the application of the inverse-square law for nearby stars. If a star is close enough to us we see it move relative to distant stars as we orbit the Sun through Parallax. By measuring how much it appears to move we can estimate the distance to the star. If we know the distance to the star, and we ca ...
... the application of the inverse-square law for nearby stars. If a star is close enough to us we see it move relative to distant stars as we orbit the Sun through Parallax. By measuring how much it appears to move we can estimate the distance to the star. If we know the distance to the star, and we ca ...
ASTRO-114--Lecture 40-
... very low mass, not too much material, it’s gonna be a small red star. If it had a lot of material that fell in, it’s gonna be a big, bright, hot star. And so that’s where you get that main sequence of the H-R diagram. All the stars become stars and the only difference from one star to another is how ...
... very low mass, not too much material, it’s gonna be a small red star. If it had a lot of material that fell in, it’s gonna be a big, bright, hot star. And so that’s where you get that main sequence of the H-R diagram. All the stars become stars and the only difference from one star to another is how ...
Today in Astronomy 142
... and an equation of state that includes the strong interaction. The maximum mass is about 2.2 M⊙; it could not possibly be > 3 M⊙. ! Neutron stars generally have very large magnetic fields (conservation of flux) and rotate rapidly (conservation of angular momentum), and are observed as pulsars: appar ...
... and an equation of state that includes the strong interaction. The maximum mass is about 2.2 M⊙; it could not possibly be > 3 M⊙. ! Neutron stars generally have very large magnetic fields (conservation of flux) and rotate rapidly (conservation of angular momentum), and are observed as pulsars: appar ...
PPS
... colours as O, B, A, F, G and M in decreasing order of the temperature. O stars, at one extreme of the classification, are blue-white and show features due to ionized helium in their spectra; G stars, which are much cooler and orange-yellow in colour, show strong lines associated with ionized calcium ...
... colours as O, B, A, F, G and M in decreasing order of the temperature. O stars, at one extreme of the classification, are blue-white and show features due to ionized helium in their spectra; G stars, which are much cooler and orange-yellow in colour, show strong lines associated with ionized calcium ...
File
... Note that there are physical reasons why longlived stars have these properties: They are less luminous because they burn their fuel at a much lower rate than shortlived stars; they burn it at this lower rate because they are less massive (which means less compression and hence a lower fusion rate ...
... Note that there are physical reasons why longlived stars have these properties: They are less luminous because they burn their fuel at a much lower rate than shortlived stars; they burn it at this lower rate because they are less massive (which means less compression and hence a lower fusion rate ...
Stellar classification
In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Light from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with absorption lines. Each line indicates an ion of a certain chemical element, with the line strength indicating the abundance of that ion. The relative abundance of the different ions varies with the temperature of the photosphere. The spectral class of a star is a short code summarizing the ionization state, giving an objective measure of the photosphere's temperature and density.Most stars are currently classified under the Morgan–Keenan (MK) system using the letters O, B, A, F, G, K, and M, a sequence from the hottest (O type) to the coolest (M type). Each letter class is then subdivided using a numeric digit with 0 being hottest and 9 being coolest (e.g. A8, A9, F0, F1 form a sequence from hotter to cooler). The sequence has been expanded with classes for other stars and star-like objects that do not fit in the classical system, such class D for white dwarfs and class C for carbon stars.In the MK system a luminosity class is added to the spectral class using Roman numerals. This is based on the width of certain absorption lines in the star's spectrum which vary with the density of the atmosphere and so distinguish giant stars from dwarfs. Luminosity class 0 or Ia+ stars for hypergiants, class I stars for supergiants, class II for bright giants, class III for regular giants, class IV for sub-giants, class V for main-sequence stars, class sd for sub-dwarfs, and class D for white dwarfs. The full spectral class for the Sun is then G2V, indicating a main-sequence star with a temperature around 5,800K.