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Galaxies - Center for Astrostatistics
... There is an intricate relationship between the interstellar medium and stars in the Galactic disk. Star are born in cold molecular clouds., orbit the Galactic Center for billions of years, become red giants, and return heavy elements like CNO into the interstellar medium via planetary nebulae and su ...
... There is an intricate relationship between the interstellar medium and stars in the Galactic disk. Star are born in cold molecular clouds., orbit the Galactic Center for billions of years, become red giants, and return heavy elements like CNO into the interstellar medium via planetary nebulae and su ...
molecular observations of H CO , 13CO, HCN how to determine
... Fig. 14.— Locations of young stars in Taurus superimposed on map of the H2 column density. The stellar positions are from Kenyon (2007). The diamonds indicate diffuse or extended sources (of which there are 44 in the region mapped), the squares indicate Class I or younger stars (18), and the asterisk ...
... Fig. 14.— Locations of young stars in Taurus superimposed on map of the H2 column density. The stellar positions are from Kenyon (2007). The diamonds indicate diffuse or extended sources (of which there are 44 in the region mapped), the squares indicate Class I or younger stars (18), and the asterisk ...
Young Galaxies Grow - Astronomical Society of the Pacific
... extended than seen in visible images of the galaxy. Ultravioletbright, thin structures stretch to almost five times the galaxy’s optical radius. • Another spiral galaxy showed a similar extended Ultraviolet disk. So astronomers began to look at several such galaxies with GALEX; one third appeared l ...
... extended than seen in visible images of the galaxy. Ultravioletbright, thin structures stretch to almost five times the galaxy’s optical radius. • Another spiral galaxy showed a similar extended Ultraviolet disk. So astronomers began to look at several such galaxies with GALEX; one third appeared l ...
Introduction to VLTI and first scientific results
... Differential phases; baseline lengths 43 m, 58 m, 89 m; medium spectral resolution1500 ...
... Differential phases; baseline lengths 43 m, 58 m, 89 m; medium spectral resolution1500 ...
Disk
... outflow detection rate = 40-90% in massive YSOs (luminous IRAS sources, UC HIIs, H2O masers,…) (Osterloh et al., Beuther et al., Zhang et al., …) disks should be widespread! ...
... outflow detection rate = 40-90% in massive YSOs (luminous IRAS sources, UC HIIs, H2O masers,…) (Osterloh et al., Beuther et al., Zhang et al., …) disks should be widespread! ...
Lecture notes 8
... Saha Equation: Need to incorporate the relative number of atoms in different stages of ionization. Let χi be the ionization energy needed to remove an electron from an atom (or ion). For example, to convert neutral hydrogen (H I = H0) to ionized hydrogen (H II =H+) you can have χi = 13.6 eV for hydr ...
... Saha Equation: Need to incorporate the relative number of atoms in different stages of ionization. Let χi be the ionization energy needed to remove an electron from an atom (or ion). For example, to convert neutral hydrogen (H I = H0) to ionized hydrogen (H II =H+) you can have χi = 13.6 eV for hydr ...
CEA - Nuclear astrophysics
... totally or partially separated from the positively electrically charged nuclei. This gas is also known as plasma. With the naked eye or a telescope, we can only see the bright surface of the stars. In astrophysics, many discoveries have been made over recent years using ground-based telescopes or te ...
... totally or partially separated from the positively electrically charged nuclei. This gas is also known as plasma. With the naked eye or a telescope, we can only see the bright surface of the stars. In astrophysics, many discoveries have been made over recent years using ground-based telescopes or te ...
the opportunities and challenges for astrometry in the 21st century
... described, for example, by Vasilevskis, Klemola, & Preston (1958) and Platais et al. (2003). In the past it was necessary to wait 20 to 30 years after the first-epoch plates were taken to repeat them and determine the proper motions. However, with the new technology we can repeat the exposures after ...
... described, for example, by Vasilevskis, Klemola, & Preston (1958) and Platais et al. (2003). In the past it was necessary to wait 20 to 30 years after the first-epoch plates were taken to repeat them and determine the proper motions. However, with the new technology we can repeat the exposures after ...
On the Frequency of Giant Planets in the Metal
... M-dwarfs are very attractive targets for simple reasons: –they are the most numerous –the low primary masses imply that very low-mass secondaries may be detected by Doppler surveys –transits by rocky planets can be detected with relatively modest precision –transiting objects will have short periods ...
... M-dwarfs are very attractive targets for simple reasons: –they are the most numerous –the low primary masses imply that very low-mass secondaries may be detected by Doppler surveys –transits by rocky planets can be detected with relatively modest precision –transiting objects will have short periods ...
IEEE 2 Column Format
... interstellar medium, (viii) age of a star, (ix) the effect of tidal forces of nearby stars, and (x) nucleus activities in interior of star. The variable candidates were identified by inspecting their light curves [1]. The identification of variable stars is a crucial task due to following reasons: ( ...
... interstellar medium, (viii) age of a star, (ix) the effect of tidal forces of nearby stars, and (x) nucleus activities in interior of star. The variable candidates were identified by inspecting their light curves [1]. The identification of variable stars is a crucial task due to following reasons: ( ...
The Milky Way Galaxy 1 Introduction 2 Globular Clusters and
... The Milky Way galaxy is our home in the universe, an island of stars among countless billions of other islands of stars in the vastness of space. Looking at diagrams of its structure, with its graceful spiral arms, one is struck by its beauty. Why does it have spiral arms, and what is their signific ...
... The Milky Way galaxy is our home in the universe, an island of stars among countless billions of other islands of stars in the vastness of space. Looking at diagrams of its structure, with its graceful spiral arms, one is struck by its beauty. Why does it have spiral arms, and what is their signific ...
Chapter 3b powerpoint presentation
... I can now tell you is equivalent to mo = -2.5 log (the flux of the zero magnitude star Vega). So, for a star of magnitude m* we can write m* - mo = 2.5 log {fo/f*} Note: There is no constant ! In this equation mo = 0 of course because it is the magnitude of a zero magnitude star. However, the flux o ...
... I can now tell you is equivalent to mo = -2.5 log (the flux of the zero magnitude star Vega). So, for a star of magnitude m* we can write m* - mo = 2.5 log {fo/f*} Note: There is no constant ! In this equation mo = 0 of course because it is the magnitude of a zero magnitude star. However, the flux o ...
Chapter 7 Stellar models and stellar stability
... as an initial condition. This is the case if one considers pre-main sequence stars. Fortunately, as we shall see later, in this case there is also a simplifying circumstance: pre-main sequence stars start out as fully convective gas spheres. This means that their temperature and pressure stratificat ...
... as an initial condition. This is the case if one considers pre-main sequence stars. Fortunately, as we shall see later, in this case there is also a simplifying circumstance: pre-main sequence stars start out as fully convective gas spheres. This means that their temperature and pressure stratificat ...
A neutron star with a carbon atmosphere in the Cassiopeia A
... component, for example, a second blackbody or atmosphere spectrum, which produced inferred R∞ of ≈ 0.2 and 2 km for blackbody fits or 0.4 and 11 km for H atmosphere fits.4 The high-temperature component has been interpreted as being due to a small hot polar cap, while the low-temperature component i ...
... component, for example, a second blackbody or atmosphere spectrum, which produced inferred R∞ of ≈ 0.2 and 2 km for blackbody fits or 0.4 and 11 km for H atmosphere fits.4 The high-temperature component has been interpreted as being due to a small hot polar cap, while the low-temperature component i ...
What Lies Beyond
... rate at which electromagnetic energy is emitted from a celestial object Proper motion is the term for the angular velocity of a star as measured from the Sun Proper motion is opposed to observed motion that is due to Earth’s movement Chapter 4, Lesson 2 ...
... rate at which electromagnetic energy is emitted from a celestial object Proper motion is the term for the angular velocity of a star as measured from the Sun Proper motion is opposed to observed motion that is due to Earth’s movement Chapter 4, Lesson 2 ...
A substellar component orbiting the F
... in the range of 3−10 MJup hinting that more massive stars tend to have more massive planets. Interestingly, the well known relation between metallicity and planet frequency for solar-like stars is less pronounced in giant stars (Schuler et al. 2005). Pasquini et al. (2007) argued that the planet-met ...
... in the range of 3−10 MJup hinting that more massive stars tend to have more massive planets. Interestingly, the well known relation between metallicity and planet frequency for solar-like stars is less pronounced in giant stars (Schuler et al. 2005). Pasquini et al. (2007) argued that the planet-met ...
3. Solar System Formation and Early Evolution
... general and for the origin of the solar system in particular, because of the short time evolution of the circumstellar disks around young stars (see Section 3.2.1). To simplify, there are two extreme possibilities for the birthplace of the Sun: (i) The Sun was born in a ‘‘rich’’, Orion-like environm ...
... general and for the origin of the solar system in particular, because of the short time evolution of the circumstellar disks around young stars (see Section 3.2.1). To simplify, there are two extreme possibilities for the birthplace of the Sun: (i) The Sun was born in a ‘‘rich’’, Orion-like environm ...
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... Starburst can drive winds of enriched gas (e.g., from supernova ejecta) out to the intergalactic medium. This gas can then be accreted again by galaxies. In a disk galaxy, the winds are generally bipolar outflows ...
... Starburst can drive winds of enriched gas (e.g., from supernova ejecta) out to the intergalactic medium. This gas can then be accreted again by galaxies. In a disk galaxy, the winds are generally bipolar outflows ...
Project 9: Stellar Spectra: Temperature
... low efficiency of absorption, whereas that of ionized calcium is very high. The efficiency depends on the availability of electrons to move to higher energies and on atomic factors, namely the likelihood of absorption in the presence of a passing photon. The efficiencies ...
... low efficiency of absorption, whereas that of ionized calcium is very high. The efficiency depends on the availability of electrons to move to higher energies and on atomic factors, namely the likelihood of absorption in the presence of a passing photon. The efficiencies ...
A Modern Search for Wolf-Rayet Stars in the Magellanic Clouds. III
... rare type of WR in the LMC. This discovery prompted us to begin a multi-year survey of both the SMC and LMC in an effort to obtain a complete census of their Wolf-Rayet population. In part this was motivated in terms of finding a more accurate value for the relative number of WC- and WN-type WRs, as ...
... rare type of WR in the LMC. This discovery prompted us to begin a multi-year survey of both the SMC and LMC in an effort to obtain a complete census of their Wolf-Rayet population. In part this was motivated in terms of finding a more accurate value for the relative number of WC- and WN-type WRs, as ...
Chapter 8
... star formation exists, in other words: given certain initial conditions (e.g. the density and temperature distributions inside an interstellar cloud) it is as yet not possible to predict, for instance, the star formation efficiency (which fraction of the gas is turned into stars) and the resulting i ...
... star formation exists, in other words: given certain initial conditions (e.g. the density and temperature distributions inside an interstellar cloud) it is as yet not possible to predict, for instance, the star formation efficiency (which fraction of the gas is turned into stars) and the resulting i ...
Slide 1
... observations of the accelerating expansion of the universe. Cold Dark Matter is explained as being cold its velocity is non-relativistic (v<
... observations of the accelerating expansion of the universe. Cold Dark Matter is explained as being cold its velocity is non-relativistic (v<
Planetary nebula
![](https://commons.wikimedia.org/wiki/Special:FilePath/NGC6543.jpg?width=300)
A planetary nebula, often abbreviated as PN or plural PNe, is a kind of emission nebula consisting of an expanding glowing shell of ionized gas ejected from old red giant stars late in their lives. The word ""nebula"" is Latin for mist or cloud and the term ""planetary nebula"" is a misnomer that originated in the 1780s with astronomer William Herschel because when viewed through his telescope, these objects appeared to him to resemble the rounded shapes of planets. Herschel's name for these objects was popularly adopted and has not been changed. They are a relatively short-lived phenomenon, lasting a few tens of thousands of years, compared to a typical stellar lifetime of several billion years.A mechanism for formation of most planetary nebulae is thought to be the following: at the end of the star's life, during the red giant phase, the outer layers of the star are expelled by strong stellar winds. Eventually, after most of the red giant's atmosphere is dissipated, the exposed hot, luminous core emits ultraviolet radiation to ionize the ejected outer layers of the star. Absorbed ultraviolet light energises the shell of nebulous gas around the central star, appearing as a bright coloured planetary nebula at several discrete visible wavelengths.Planetary nebulae may play a crucial role in the chemical evolution of the Milky Way, returning material to the interstellar medium from stars where elements, the products of nucleosynthesis (such as carbon, nitrogen, oxygen and neon), have been created. Planetary nebulae are also observed in more distant galaxies, yielding useful information about their chemical abundances.In recent years, Hubble Space Telescope images have revealed many planetary nebulae to have extremely complex and varied morphologies. About one-fifth are roughly spherical, but the majority are not spherically symmetric. The mechanisms which produce such a wide variety of shapes and features are not yet well understood, but binary central stars, stellar winds and magnetic fields may play a role.