@let@token Stellar Oscillations: Pulsations of Stars Throughout the
... We analyze the stability of g-modes in white dwarfs with hydrogen envelopes. All relevant physical processes take place in the outer layer of hydrogen-rich material, which consists of a radiative layer overlaid by a convective envelope. The radiative layer contributes to mode damping, because its op ...
... We analyze the stability of g-modes in white dwarfs with hydrogen envelopes. All relevant physical processes take place in the outer layer of hydrogen-rich material, which consists of a radiative layer overlaid by a convective envelope. The radiative layer contributes to mode damping, because its op ...
5 Report of the Panel on Stars and Stellar Evolution
... the end of every talk and rouses himself to ask, to great approbation for his subliminal understanding, “Yes, all very interesting, but what about rotation and magnetic fields?” Astronomers are now in a position to address this question in a serious way. In the Sun, the effects are visible; in many ...
... the end of every talk and rouses himself to ask, to great approbation for his subliminal understanding, “Yes, all very interesting, but what about rotation and magnetic fields?” Astronomers are now in a position to address this question in a serious way. In the Sun, the effects are visible; in many ...
INTERSTELLAR MedLab
... Dark – high densities of dust and gas that redden or extinct the light from the stars located behind the cloud. These are also where molecules are likely to be found. During the course of this laboratory exercise, you will study the interstellar medium – where stars are formed and into which the ste ...
... Dark – high densities of dust and gas that redden or extinct the light from the stars located behind the cloud. These are also where molecules are likely to be found. During the course of this laboratory exercise, you will study the interstellar medium – where stars are formed and into which the ste ...
Next Generation Sunshine State Standards Chapter 24
... sizes, temperatures, and distances, so their apparent brightnesses vary widely. Apparent Magnitude Stars have been classified according to their apparent brightness since at least the second century BC, when Hipparchus placed about 850 of them into six categories based on his ability to see differen ...
... sizes, temperatures, and distances, so their apparent brightnesses vary widely. Apparent Magnitude Stars have been classified according to their apparent brightness since at least the second century BC, when Hipparchus placed about 850 of them into six categories based on his ability to see differen ...
Lab PDF - NMSU Astronomy
... On a clear, dark night, one might see more than two thousand stars. Unlike our distant ancestors, we recognize that each one is a huge ball of hot gas that radiates energy, like our own (very nearby) star, the Sun. Like the Sun, the stars shine by converting hydrogen into helium via nuclear fusion r ...
... On a clear, dark night, one might see more than two thousand stars. Unlike our distant ancestors, we recognize that each one is a huge ball of hot gas that radiates energy, like our own (very nearby) star, the Sun. Like the Sun, the stars shine by converting hydrogen into helium via nuclear fusion r ...
Doppler imaging of stellar surfaces
... rise to doubts about the reliability of specific types of features. The potential for generating artifacts in DI reconstructions have led some of us to run tests comparing the reconstruction of images from artificial data, where incorrect parameters have been used in the reconstruction, with the ori ...
... rise to doubts about the reliability of specific types of features. The potential for generating artifacts in DI reconstructions have led some of us to run tests comparing the reconstruction of images from artificial data, where incorrect parameters have been used in the reconstruction, with the ori ...
Shortв•`lived radioactivity in the early solar system: The Superв•`AGB
... Soni (2006) pollution of 26Al due to the winds of lowmass AGB stars (initial masses lower than approximately 1.5 Mx) and Wolf-Rayet stars (initial masses higher than approximately 60 Mx) would have left no signature in the O isotopic composition. These two stellar sources do not produce 60Fe and to ...
... Soni (2006) pollution of 26Al due to the winds of lowmass AGB stars (initial masses lower than approximately 1.5 Mx) and Wolf-Rayet stars (initial masses higher than approximately 60 Mx) would have left no signature in the O isotopic composition. These two stellar sources do not produce 60Fe and to ...
1. INTRODUCTION - Institut für Theoretische Astrophysik
... emission in these lines and the observed basal Ñux emission, which had been suspected to be due to nonmagnetic (i.e., acoustic) heating operating in all late-type stars. The height dependence of the acoustic energy Ñux can be explained by the limiting strength property of the acoustic shocks and is ...
... emission in these lines and the observed basal Ñux emission, which had been suspected to be due to nonmagnetic (i.e., acoustic) heating operating in all late-type stars. The height dependence of the acoustic energy Ñux can be explained by the limiting strength property of the acoustic shocks and is ...
2. The Anatomy of Stellar Life and Death
... Observations by Henrik Beuther (University of Heidelberg) and Peter Schilke (University of Cologne) of a star-forming region IRAS 19410–2336 revealed that the process of massive stars formation appeared to mirror that of lower mass star formation with a very similar scaling of the mass of protostars ...
... Observations by Henrik Beuther (University of Heidelberg) and Peter Schilke (University of Cologne) of a star-forming region IRAS 19410–2336 revealed that the process of massive stars formation appeared to mirror that of lower mass star formation with a very similar scaling of the mass of protostars ...
Main-Sequence Stars and the Sun
... relation to the surface temperature of the star is as follows. Hydrogen Balmer lines. Absorption lines caused by hydrogen atoms that are initially in the first excited state (see Chapter 1) are referred to as Balmer lines. At low surface temperatures, most of the hydrogen atoms are in the ground sta ...
... relation to the surface temperature of the star is as follows. Hydrogen Balmer lines. Absorption lines caused by hydrogen atoms that are initially in the first excited state (see Chapter 1) are referred to as Balmer lines. At low surface temperatures, most of the hydrogen atoms are in the ground sta ...
silicon and oxygen abundances in planet-host stars
... no such differences in their sample for alpha- and iron-peak elements. They observe no difference in the overall trends of [X/Fe] between planet hosts and their volume-limited sample of stars without any known planetary-mass companions. Based on their results, stars with planets appear to be indisti ...
... no such differences in their sample for alpha- and iron-peak elements. They observe no difference in the overall trends of [X/Fe] between planet hosts and their volume-limited sample of stars without any known planetary-mass companions. Based on their results, stars with planets appear to be indisti ...
POSTERS SESSION I: Atmospheres of Massive Stars
... be directly measured from the Doppler broadening of their photospheric lines. In Wolf-Rayet (WR) stars, however, such measurements are impossible, since their continuum emission is formed in the dense wind that hides the hydrostatic, stellar surface. Here, we present a technique to derive the rotati ...
... be directly measured from the Doppler broadening of their photospheric lines. In Wolf-Rayet (WR) stars, however, such measurements are impossible, since their continuum emission is formed in the dense wind that hides the hydrostatic, stellar surface. Here, we present a technique to derive the rotati ...
Statistical properties of a sample of periodically variable B-type supergiants ⋆
... Waelkens et al. (1998) positioned the new periodic B supergiants in the HR diagram on the basis of multicolour photometric calibrations (accurate parallaxes are not available) and found them to be situated between the SPBs and previously known α Cyg-type variables (see their Fig. 2). Oscillations we ...
... Waelkens et al. (1998) positioned the new periodic B supergiants in the HR diagram on the basis of multicolour photometric calibrations (accurate parallaxes are not available) and found them to be situated between the SPBs and previously known α Cyg-type variables (see their Fig. 2). Oscillations we ...
VY Canis Majoris: The Astrophysical Basis of Its Luminosity
... Flower 1977) yields Tef f ∼ 3200◦ for an M4-M5 star. However, one should be cautious in the case of VY CMa; we are not observing either its photosphere or its surface directly. It has been known for some time that VY CMa’s absorption spectrum is significantly redshifted with respect to its systemic ...
... Flower 1977) yields Tef f ∼ 3200◦ for an M4-M5 star. However, one should be cautious in the case of VY CMa; we are not observing either its photosphere or its surface directly. It has been known for some time that VY CMa’s absorption spectrum is significantly redshifted with respect to its systemic ...
Lecture Topics 1023
... ASTR 1023 Lecture Topics These are the headings of the paragraphs into which ASTR 1023 lectures are divided. Use them to check your notes for completeness, and to see how the course is organized. It is also a good idea to cross-check these topics with your reading assignments, because some topics ar ...
... ASTR 1023 Lecture Topics These are the headings of the paragraphs into which ASTR 1023 lectures are divided. Use them to check your notes for completeness, and to see how the course is organized. It is also a good idea to cross-check these topics with your reading assignments, because some topics ar ...
Rotation Periods of Wide Binaries in the Kepler Field
... Because most of the stars that satisfy the present criteria are relatively nearby, they should be expected to have low interstellar reddening. In any case, since the two components presumably lie at the same distance, the reddening would be expected to be the same, and so will not affect Figure 1. T ...
... Because most of the stars that satisfy the present criteria are relatively nearby, they should be expected to have low interstellar reddening. In any case, since the two components presumably lie at the same distance, the reddening would be expected to be the same, and so will not affect Figure 1. T ...
Chapter 30: Stars
... as shown in Figure 30-1B, because it emits most strongly in a narrow band of red wavelengths. The top layer of the Sun’s atmosphere, called the corona, extends several million kilometers from the top of the chromosphere and has a temperature range of 1 million to 2 million K. The density of the gas ...
... as shown in Figure 30-1B, because it emits most strongly in a narrow band of red wavelengths. The top layer of the Sun’s atmosphere, called the corona, extends several million kilometers from the top of the chromosphere and has a temperature range of 1 million to 2 million K. The density of the gas ...
Notes on Stars
... this observation. The real starting point of solar (and stellar) spectroscopy were Fraunhofers pioneering studies in 1816-1820 in Benediktbeuren and in the Munich Observatory together with von Soldner. Fraunhofer discovered numerous absorption lines in the solar spectrum and documented them with imp ...
... this observation. The real starting point of solar (and stellar) spectroscopy were Fraunhofers pioneering studies in 1816-1820 in Benediktbeuren and in the Munich Observatory together with von Soldner. Fraunhofer discovered numerous absorption lines in the solar spectrum and documented them with imp ...
Protostellar/PMS Mass Infall Luminosity Problem
... mass, as in the Herschel Orion Protostar Survey (HOPS, Manoj et al. 2013; Fisher et al. 2013; Stutz et al. 2013) ...
... mass, as in the Herschel Orion Protostar Survey (HOPS, Manoj et al. 2013; Fisher et al. 2013; Stutz et al. 2013) ...
Planetary Nebulae: Observational Properties, Mimics, and Diagnostics
... By definition, a PN surrounds a hot, low-mass CS, which may in fact be off-centre in some old examples due to an asymmetric ISM interaction (see Wareing 2010, and Sabin et al. 2010, in this issue). The CS has a temperature of at least 20,000 K (up to ∼250,000 K), and a mass between the empirical lim ...
... By definition, a PN surrounds a hot, low-mass CS, which may in fact be off-centre in some old examples due to an asymmetric ISM interaction (see Wareing 2010, and Sabin et al. 2010, in this issue). The CS has a temperature of at least 20,000 K (up to ∼250,000 K), and a mass between the empirical lim ...
the chandra deep field–north survey. xvii. evolution of
... The X-ray data utilized here are part of the 2 Ms CDF-N survey obtained with the Advanced CCD Imaging Spectrometer (ACIS) detector on board the Chandra X-Ray Observatory. The satellite and detector are described by Weisskopf et al. (2002). Extragalactic results from the CDF-N project are described i ...
... The X-ray data utilized here are part of the 2 Ms CDF-N survey obtained with the Advanced CCD Imaging Spectrometer (ACIS) detector on board the Chandra X-Ray Observatory. The satellite and detector are described by Weisskopf et al. (2002). Extragalactic results from the CDF-N project are described i ...
CHAPTER 1 The Formation and Structure of Stars
... • The thermal energy in clouds of gas causes them to resist collapse. – Temperature is a measure of the motion of the atoms or molecules in a material—in a hot gas, the atoms move more rapidly than do those in a cool gas. – Although the interstellar clouds are very cold, even at a temperature of onl ...
... • The thermal energy in clouds of gas causes them to resist collapse. – Temperature is a measure of the motion of the atoms or molecules in a material—in a hot gas, the atoms move more rapidly than do those in a cool gas. – Although the interstellar clouds are very cold, even at a temperature of onl ...
Curiosities of the Sky
... openings in the sky, for as one continues to gaze it loses its purely metaphysical quality and becomes a kind of entity, like the ocean. The observer is conscious that he can actually see the beginning of its ebon depths, in which the visible universe appears to float like an enchanted island, respl ...
... openings in the sky, for as one continues to gaze it loses its purely metaphysical quality and becomes a kind of entity, like the ocean. The observer is conscious that he can actually see the beginning of its ebon depths, in which the visible universe appears to float like an enchanted island, respl ...
with answers
... ● not all of the energy from the Sun comes from the proton-proton chain, meaning that some of the luminosity from the Sun comes from other nuclear reactions within the Sun. ● the reaction and consumption of hydrogen in a star is not linear or constant, but may fluctuate over time, especially as a st ...
... ● not all of the energy from the Sun comes from the proton-proton chain, meaning that some of the luminosity from the Sun comes from other nuclear reactions within the Sun. ● the reaction and consumption of hydrogen in a star is not linear or constant, but may fluctuate over time, especially as a st ...
Red supergiants and the past of Cygnus OB2
... have already evolved away from the main sequence and that the main star-forming sites have been shifting with time. The study of this older component is made difficult by the effects of stellar evolution, and in particular by the fact that its most massive components have already disappeared as supe ...
... have already evolved away from the main sequence and that the main star-forming sites have been shifting with time. The study of this older component is made difficult by the effects of stellar evolution, and in particular by the fact that its most massive components have already disappeared as supe ...
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.