PH607 – Galaxies
... Star Formation: Since spiral arms contain giant molecular clouds (the material from which stars are made), and also contain O and B stars (newly made, short-lived stars), it is apparent that spiral arms are where star formation takes place. Because O and B stars are very luminous, spiral arms are ve ...
... Star Formation: Since spiral arms contain giant molecular clouds (the material from which stars are made), and also contain O and B stars (newly made, short-lived stars), it is apparent that spiral arms are where star formation takes place. Because O and B stars are very luminous, spiral arms are ve ...
Precision age indicators that exploit chemically peculiar stars
... Finally, coolest of all, C stars arise late in the lives of 1.5−4 M stars on the asymptotic giant branch where a third dredge-up convects sufficient C to the surface to tip the number ratio C/O > 1 (Marigo et al. 2008). The mass range translates to population ages between 0.5 and 5 Gyr for heavy elem ...
... Finally, coolest of all, C stars arise late in the lives of 1.5−4 M stars on the asymptotic giant branch where a third dredge-up convects sufficient C to the surface to tip the number ratio C/O > 1 (Marigo et al. 2008). The mass range translates to population ages between 0.5 and 5 Gyr for heavy elem ...
Neutron stars and quark stars - Goethe
... similar masses and radii, cooling, surface (crust), . . . but look for • extremely small mass, small radius stars (includes strangelets!) • strange dwarfs: small and light white dwarfs with a strange star core (Glendenning, Kettner, Weber, 1995) • super-Eddington luminosity from bare, hot strange st ...
... similar masses and radii, cooling, surface (crust), . . . but look for • extremely small mass, small radius stars (includes strangelets!) • strange dwarfs: small and light white dwarfs with a strange star core (Glendenning, Kettner, Weber, 1995) • super-Eddington luminosity from bare, hot strange st ...
Mark Rubin
... • The gas is easily enriched above zcrit. For this reason , the average contribution from pristine, metal-free stars to the total cosmic star formation density is dominant only in the very early phases of structure formation, while it drops below ~10-3 quite rapidly, after the explosion of the firs ...
... • The gas is easily enriched above zcrit. For this reason , the average contribution from pristine, metal-free stars to the total cosmic star formation density is dominant only in the very early phases of structure formation, while it drops below ~10-3 quite rapidly, after the explosion of the firs ...
Astrophysics notes
... Describe the key features of stellar spectra and describe how these are used to classify stars (6 marks) Different atoms and molecules produce spectral lines of very different strengths at different temperatures. At lower temps, molecular absorption lines are observed. At hotter temperatures, neutra ...
... Describe the key features of stellar spectra and describe how these are used to classify stars (6 marks) Different atoms and molecules produce spectral lines of very different strengths at different temperatures. At lower temps, molecular absorption lines are observed. At hotter temperatures, neutra ...
Star Birth
... • Without CO molecules to provide cooling, the clouds that formed the first stars had to be considerably warmer than today’s molecular clouds • The first stars must therefore have been more massive than most of today’s stars, for gravity to overcome pressure ...
... • Without CO molecules to provide cooling, the clouds that formed the first stars had to be considerably warmer than today’s molecular clouds • The first stars must therefore have been more massive than most of today’s stars, for gravity to overcome pressure ...
Continuous, Emission, and Absorption Line Spectra
... Go back to your lab and look at the spectra of the gas tubes. Draw which lines you see, and then identify the gases by comparing the spectra to the spectra in the appendix. Read off the wavelengths of the major emission lines and write those numbers in the space below your drawings. [Note you will o ...
... Go back to your lab and look at the spectra of the gas tubes. Draw which lines you see, and then identify the gases by comparing the spectra to the spectra in the appendix. Read off the wavelengths of the major emission lines and write those numbers in the space below your drawings. [Note you will o ...
Foreword - Peter Zamarovský
... If we look around us in the forest, what do we see? Trees upon trees. In whichever direction we look in, we see a tree. Trees fill the entire field of view around us (at ground level, at least). And the same should apply to the forest of stars in cosmic space: there should be one shining in every di ...
... If we look around us in the forest, what do we see? Trees upon trees. In whichever direction we look in, we see a tree. Trees fill the entire field of view around us (at ground level, at least). And the same should apply to the forest of stars in cosmic space: there should be one shining in every di ...
Stellar Evolution - University of California, Santa Cruz
... • Upper mass limit is around 100 solar masses set by inability for a star to hang on to its outer layers because high radiation pressure (high luminosity). ...
... • Upper mass limit is around 100 solar masses set by inability for a star to hang on to its outer layers because high radiation pressure (high luminosity). ...
Good Vibrations and Stellar Pulsations - Physics
... Some Results for the Sun • base of convection zone at 0.714 Rsun, where T = 2.18 x 106 K • mass fraction of helium at surface is Y = 0.2437 • helioseismologically measured sound speed and calculated sound speed for standard solar model agree to within 0.1% ...
... Some Results for the Sun • base of convection zone at 0.714 Rsun, where T = 2.18 x 106 K • mass fraction of helium at surface is Y = 0.2437 • helioseismologically measured sound speed and calculated sound speed for standard solar model agree to within 0.1% ...
Chapter 13 The Life of a Star The Life of a Star Mass Is the Key The
... • Stars smaller than 0.1 M rarely seen since their mass is too small for their cores to initiate fusion reactions • Objects with masses between planets and are called brown dwarfs, “failed stars” extremely dim and difficult to observe • Upper mass limit of stars (about 30 M) due to extreme tempera ...
... • Stars smaller than 0.1 M rarely seen since their mass is too small for their cores to initiate fusion reactions • Objects with masses between planets and are called brown dwarfs, “failed stars” extremely dim and difficult to observe • Upper mass limit of stars (about 30 M) due to extreme tempera ...
Chapter 13
... • Intense outward gas flows from surfaces • Occupy H-R diagram just above main-sequence ...
... • Intense outward gas flows from surfaces • Occupy H-R diagram just above main-sequence ...
Stellar Evolution – Life of a Star
... which the forces of pressure (gravity) alter the star. Stellar evolution is inevitable; stars deplete their own fuel source. Stellar evolution is very important. It is responsible for the production of most of the elements (all natural elements after H and He). As well, it aids in the formation of g ...
... which the forces of pressure (gravity) alter the star. Stellar evolution is inevitable; stars deplete their own fuel source. Stellar evolution is very important. It is responsible for the production of most of the elements (all natural elements after H and He). As well, it aids in the formation of g ...
Chapter 13 section 3
... its helium and the outer layers escape into space. This leaves only the hot, dense core. At this stage in a star’s life cycle, it is about the size of Earth. It is called a white dwarf. In time, the white dwarf will cool and stop giving off light. The length time it takes for a star to go through it ...
... its helium and the outer layers escape into space. This leaves only the hot, dense core. At this stage in a star’s life cycle, it is about the size of Earth. It is called a white dwarf. In time, the white dwarf will cool and stop giving off light. The length time it takes for a star to go through it ...
ASTRONOMY 120
... How do astronomers test the theory of stellar evolution? (3 points) Stars change so slowly over time, that we have no hope of observing the changes they go through directly in a human lifetime or even in all of human history. However, we have a galaxy full of many stars at different stages of develo ...
... How do astronomers test the theory of stellar evolution? (3 points) Stars change so slowly over time, that we have no hope of observing the changes they go through directly in a human lifetime or even in all of human history. However, we have a galaxy full of many stars at different stages of develo ...
14 The Interstellar Medium and Star Formation
... Dust grains are known to be elongated, rather than spherical, because they polarize light passing through them. They also may be slightly conductive because they polarize and rotate radio waves. ...
... Dust grains are known to be elongated, rather than spherical, because they polarize light passing through them. They also may be slightly conductive because they polarize and rotate radio waves. ...
Direct Detection of Galactic Halo Dark Matter
... Way galaxy has been inferred because the gravitational field due to the known distribution of luminous matter, primarily stars, cannot explain the observed rotational characteristics of the galaxy’s spiral disk. A substantial portion of this unseen matter may be old, very cool white dwarfs (1–4). A ...
... Way galaxy has been inferred because the gravitational field due to the known distribution of luminous matter, primarily stars, cannot explain the observed rotational characteristics of the galaxy’s spiral disk. A substantial portion of this unseen matter may be old, very cool white dwarfs (1–4). A ...
A Spectroscopic Study of the RV Tauri Stars TT Oph... Guillermo Hernandez , Donald K. Walter , Jennifer Cash
... spectral type using Gray & Corbally (2009) standards. Photometric data were taken from the AAVSO dataset to determine the apparent magnitude (m) on each date. Stellar distance (d) was derived from the Hipparcos-Tyco parallax database for TT Oph. The absolute magnitude (M) for TT Oph was calcul ...
... spectral type using Gray & Corbally (2009) standards. Photometric data were taken from the AAVSO dataset to determine the apparent magnitude (m) on each date. Stellar distance (d) was derived from the Hipparcos-Tyco parallax database for TT Oph. The absolute magnitude (M) for TT Oph was calcul ...
Part I Light, Telescopes, Atoms and Stars
... ionized), Medium stars = strong lines (correct amount of energy for these lines in the collisions caused by the temperature) ...
... ionized), Medium stars = strong lines (correct amount of energy for these lines in the collisions caused by the temperature) ...
Powerpoint
... H I Gas and 21-cm radiation Gas in which H is atomic. Fills much (most?) of interstellar space. Density ~1 atom / cm3. Too cold (~100 K) to give optical emission lines. Primarily observed through radiation of H at wavelength of 21 cm. H I accounts for almost half the mass in the ISM: ~2 x 109 MSun ...
... H I Gas and 21-cm radiation Gas in which H is atomic. Fills much (most?) of interstellar space. Density ~1 atom / cm3. Too cold (~100 K) to give optical emission lines. Primarily observed through radiation of H at wavelength of 21 cm. H I accounts for almost half the mass in the ISM: ~2 x 109 MSun ...
Astronomy (C) - North Carolina Science Olympiad
... Nothing – even light – can escape after getting too close (“event horizon”) Can’t be directly observed – must be inferred from presence of accretion disk and/or jet ...
... Nothing – even light – can escape after getting too close (“event horizon”) Can’t be directly observed – must be inferred from presence of accretion disk and/or jet ...
Low mass stars
... the Sun. The diagonal lines correspond to constant stellar radius, so that stellar size can be represented on the same diagram as luminosity and temperature. The first H-R diagrams considered stars in the solar neighbourhood and plotted absolute visual magnitude, M, versus spectral type, which is eq ...
... the Sun. The diagonal lines correspond to constant stellar radius, so that stellar size can be represented on the same diagram as luminosity and temperature. The first H-R diagrams considered stars in the solar neighbourhood and plotted absolute visual magnitude, M, versus spectral type, which is eq ...
Determination of kinetic energies of stars using Hipparcos data *
... has resulted in kind of a U-turn of the astronomical community towards stellar kinematics. This is not surprising, in view of the fact that the previous peak of the amount of works devoted to stellar kinematics was in 1930s when the General Catalogue by B. Boss became available (Boss, B. 1937). The ...
... has resulted in kind of a U-turn of the astronomical community towards stellar kinematics. This is not surprising, in view of the fact that the previous peak of the amount of works devoted to stellar kinematics was in 1930s when the General Catalogue by B. Boss became available (Boss, B. 1937). The ...
Unit 4: Astronomy
... 1) Describe how astronomers were first able to measure the distances to stars. 2) Describe the unit of the length developed by astronomers to measure and describe distances to stars other than our own sun. 3) Explain the statement “looking deep into space is essentially looking back in time”. 4) Des ...
... 1) Describe how astronomers were first able to measure the distances to stars. 2) Describe the unit of the length developed by astronomers to measure and describe distances to stars other than our own sun. 3) Explain the statement “looking deep into space is essentially looking back in time”. 4) Des ...
Beers_First_Stars_NIC_School
... times the solar mass. No clear evidence of supernovae from such supermassive stars has, however, yet been found in the chemical compositions of Milky Way stars. Here we report on an analysis of a very metal-poor star, SDSS J001820.5−093939.2, which possesses elemental-abundance ratios that differ si ...
... times the solar mass. No clear evidence of supernovae from such supermassive stars has, however, yet been found in the chemical compositions of Milky Way stars. Here we report on an analysis of a very metal-poor star, SDSS J001820.5−093939.2, which possesses elemental-abundance ratios that differ si ...
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.