![Observations of Interstellar Carbon Compounds](http://s1.studyres.com/store/data/020749837_1-750719ceae1427147b76e18c5ae039ee-300x300.png)
Observations of Interstellar Carbon Compounds
... The relative profile variations of the mid-IR emission among various astrophysical sources has been underlined since a long time from ground-based observations (Joblin et al. 1996; Geballe et al. 1997) and a classification in various classes was performed when space missions provided a full wavelength ...
... The relative profile variations of the mid-IR emission among various astrophysical sources has been underlined since a long time from ground-based observations (Joblin et al. 1996; Geballe et al. 1997) and a classification in various classes was performed when space missions provided a full wavelength ...
L101 DETECTION OF A LARGE ARC OF IONIZED HYDROGEN
... side (l p 132⬚–134⬚, b p ⫹14⬚– ⫹ 20⬚), where the Ha velocity is about ⫺62 km s⫺1, there is a corresponding H i “filament” offset approximately 2⬚ to lower longitude (i.e., to the outside of the loop) on the ⫺62.5 to ⫺55 km s⫺1 velocity interval maps of the Dwingeloo 21 cm survey (Hartmann 1994). Thi ...
... side (l p 132⬚–134⬚, b p ⫹14⬚– ⫹ 20⬚), where the Ha velocity is about ⫺62 km s⫺1, there is a corresponding H i “filament” offset approximately 2⬚ to lower longitude (i.e., to the outside of the loop) on the ⫺62.5 to ⫺55 km s⫺1 velocity interval maps of the Dwingeloo 21 cm survey (Hartmann 1994). Thi ...
masses of star clusters in the nuclei of bulgeless spiral galaxies
... In the last decade star clusters have been found in the centers of spiral galaxies across all Hubble types. We here present a spectroscopic study of the exceptionally bright (106 –108 L ) but compact (re 5 pc) nuclear star clusters in very late type spirals with the Ultraviolet and Visual Echelle ...
... In the last decade star clusters have been found in the centers of spiral galaxies across all Hubble types. We here present a spectroscopic study of the exceptionally bright (106 –108 L ) but compact (re 5 pc) nuclear star clusters in very late type spirals with the Ultraviolet and Visual Echelle ...
Lecture 2
... age (time t) and chemical composition (X, Y, Z). Composition parameterized with the notation: X = mass fraction of hydrogen H Y = mass fraction of helium He Z = mass fraction of all other elements e.g., for the Sun: X¤ = 0.747 ; Y¤ = 0.236 ; Z¤ = 0.017 Note: Z is often referred to as metallicity We ...
... age (time t) and chemical composition (X, Y, Z). Composition parameterized with the notation: X = mass fraction of hydrogen H Y = mass fraction of helium He Z = mass fraction of all other elements e.g., for the Sun: X¤ = 0.747 ; Y¤ = 0.236 ; Z¤ = 0.017 Note: Z is often referred to as metallicity We ...
Star counts in the Galaxy-Simulating from very deep to very shallow
... stars of different absolute magnitude present different scale heights (and hence ρd (r)): Bahcall & Soneira (1980, 1984; and many authors later on) assigned the scale height of 325 pc for MV > 5.1, of 90 pc for MV < 2.3 dwarfs, and linearly interpolated in between. This separation was interpreted as a ...
... stars of different absolute magnitude present different scale heights (and hence ρd (r)): Bahcall & Soneira (1980, 1984; and many authors later on) assigned the scale height of 325 pc for MV > 5.1, of 90 pc for MV < 2.3 dwarfs, and linearly interpolated in between. This separation was interpreted as a ...
Kathy Geise `08 - DU Portfolio
... The stellar atmosphere contains the outermost layers of the star and includes the region from which photons escape the star and become visible. Particles in the stellar atmosphere are not completely ionized and the temperature, pressure and density are much lower than in the interior. Stars are so l ...
... The stellar atmosphere contains the outermost layers of the star and includes the region from which photons escape the star and become visible. Particles in the stellar atmosphere are not completely ionized and the temperature, pressure and density are much lower than in the interior. Stars are so l ...
Star Formation and Young Clusters in Cygnus
... Figure 1 shows the extinction from the main molecular cloud complexes in Cygnus based on the star count data by Dobashi et al. (2005). The figure shows the Galactic plane between longitudes 67◦ and 100◦ . The Great Cygnus Rift is most prominent to the right, and the 10 degree large Cygnus X region p ...
... Figure 1 shows the extinction from the main molecular cloud complexes in Cygnus based on the star count data by Dobashi et al. (2005). The figure shows the Galactic plane between longitudes 67◦ and 100◦ . The Great Cygnus Rift is most prominent to the right, and the 10 degree large Cygnus X region p ...
The chemical case for no winds in dwarf irregular galaxies
... the metals synthesized by Type II SNe (e.g. oxygen) can be quite high, since they can be easily channelled out of the galaxy, but the ejection efficiency of pre-existing gas would generally be very low. Elements produced in low- and intermediate-mass stars, such as nitrogen and carbon, could still b ...
... the metals synthesized by Type II SNe (e.g. oxygen) can be quite high, since they can be easily channelled out of the galaxy, but the ejection efficiency of pre-existing gas would generally be very low. Elements produced in low- and intermediate-mass stars, such as nitrogen and carbon, could still b ...
The Pluto “Smackdown” and The “New” Solar System
... (X-ray/UV fluences from central star & neighboring stars? Cosmic rays?) ...
... (X-ray/UV fluences from central star & neighboring stars? Cosmic rays?) ...
Full Text - Harvard University
... and ‘mini-Neptune’ planets around M-stars have advanced significantly over the past few years (Bean et al. 2010; Croll et al. 2011; Demory et al. 2012; Kreidberg et al. 2013; Fraine et al. 2014). Hot, close-in planets around M-stars are likely to be the first rocky planets for which transit spectros ...
... and ‘mini-Neptune’ planets around M-stars have advanced significantly over the past few years (Bean et al. 2010; Croll et al. 2011; Demory et al. 2012; Kreidberg et al. 2013; Fraine et al. 2014). Hot, close-in planets around M-stars are likely to be the first rocky planets for which transit spectros ...
A variation of the fraction of stars that form in
... constrained our sample as follows. Ages between 10 and ∼300 Myr (7.0 ≤ Log(τ/yr) ≤ 8.5), masses above 5 × 103 M , magnitudes brighter than MV ≤ 22.5 and clusters with galactocentric radii equal or larger than 370 pc. The limits were chosen to avoid classification confusion for young sources (i.e. y ...
... constrained our sample as follows. Ages between 10 and ∼300 Myr (7.0 ≤ Log(τ/yr) ≤ 8.5), masses above 5 × 103 M , magnitudes brighter than MV ≤ 22.5 and clusters with galactocentric radii equal or larger than 370 pc. The limits were chosen to avoid classification confusion for young sources (i.e. y ...
A Dozen Colliding-Wind X-Ray Binaries in the Star - UvA-DARE
... We analyzed archival Chandra X-ray observations of the central portion of the 30 Doradus region in the Large Magellanic Cloud. The image contains 20 X-ray point sources with luminosities between 5 1032 and 2 1035 ergs s1 (0.2–3.5 keV). A dozen sources have bright WN Wolf-Rayet or spectral type ...
... We analyzed archival Chandra X-ray observations of the central portion of the 30 Doradus region in the Large Magellanic Cloud. The image contains 20 X-ray point sources with luminosities between 5 1032 and 2 1035 ergs s1 (0.2–3.5 keV). A dozen sources have bright WN Wolf-Rayet or spectral type ...
HS0702+ 6043: A star showing both short-period p
... 3.2. A rotating star spot? Another possible cause to be considered as the origin of the variation in HS 0702+6043 is a rotating star spot. Although single sdBs do not generally rotate very rapidly, with only one possible exception (PG 1605+072, but see Kuassivi et al. 2005), the following scenario c ...
... 3.2. A rotating star spot? Another possible cause to be considered as the origin of the variation in HS 0702+6043 is a rotating star spot. Although single sdBs do not generally rotate very rapidly, with only one possible exception (PG 1605+072, but see Kuassivi et al. 2005), the following scenario c ...
Lithium abundances for 185 main-sequence stars
... resolution spectra of 130 stars and a reanalysis of data for 55 stars from Lambert et al. (1991). The survey takes advantage of improved photometric and spectroscopic determinations of effective temperature and metallicity as well as mass and age derived from Hipparcos absolute magnitudes, offering ...
... resolution spectra of 130 stars and a reanalysis of data for 55 stars from Lambert et al. (1991). The survey takes advantage of improved photometric and spectroscopic determinations of effective temperature and metallicity as well as mass and age derived from Hipparcos absolute magnitudes, offering ...
New Scientist - Quark Nova Project
... have lower net energy and hence be more stable than nuclear matter made of protons and neutrons. ...
... have lower net energy and hence be more stable than nuclear matter made of protons and neutrons. ...
Barium Stars: Theoretical Interpretation
... Our models are based on franec (Frascati RaphsonNewton Evolutionary Code, Chieffi & Straniero 1989), coupled with a post-process code that includes a full network up to bismuth. According to franec, TDU starts after a limited number of TPs. TDU ceases when the mass of the envelope decreases by mass l ...
... Our models are based on franec (Frascati RaphsonNewton Evolutionary Code, Chieffi & Straniero 1989), coupled with a post-process code that includes a full network up to bismuth. According to franec, TDU starts after a limited number of TPs. TDU ceases when the mass of the envelope decreases by mass l ...
Core Formation in Giant Gaseous Protoplanets
... to be too high to allow the grains to sediment and form a core. We find that silicate grains evaporate immediately in objects of 5 MJ or larger, and instead of contributing to core formation, the grains evaporate in the planetary envelope enriching it with refractory material. Protoplanets with smal ...
... to be too high to allow the grains to sediment and form a core. We find that silicate grains evaporate immediately in objects of 5 MJ or larger, and instead of contributing to core formation, the grains evaporate in the planetary envelope enriching it with refractory material. Protoplanets with smal ...
Transport of angular momentum in massive stars
... larger the acceleration out of the star. Due to a non zero velocity of the absorbing atoms in the envelope the absorption lines get broadened by the Doppler effect. This increases the efficiency of the line driving mechanism, because even more photons can be absorbed. Once the mass is ejected, the s ...
... larger the acceleration out of the star. Due to a non zero velocity of the absorbing atoms in the envelope the absorption lines get broadened by the Doppler effect. This increases the efficiency of the line driving mechanism, because even more photons can be absorbed. Once the mass is ejected, the s ...
the discovery of a massive cluster of red supergiants with glimpse
... and energetic photons from young massive stars. Infrared dark clouds (IRDCs) and dark filaments appear superimposed on the bright diffuse background at many locations across this field, indicating the presence of opaque, cold clouds in the foreground. A handful of very red and bright sources, often ...
... and energetic photons from young massive stars. Infrared dark clouds (IRDCs) and dark filaments appear superimposed on the bright diffuse background at many locations across this field, indicating the presence of opaque, cold clouds in the foreground. A handful of very red and bright sources, often ...
Max Planck Institute for Gravitational Physics
... After first core collapse there may be a series of contractions/re-expansions of the core These are consequences of the fact that HEAT CAPACITY can be still negative ...
... After first core collapse there may be a series of contractions/re-expansions of the core These are consequences of the fact that HEAT CAPACITY can be still negative ...
From meteorites to evolution and habitability of planets
... The identification and preservation of life tracers is a very complicated subject that will be partly addressed in this paper. Life leaves traces by modifying microscopically or macroscopically the physical-chemical characteristics of its environment. The extent to which these modifications occur and ...
... The identification and preservation of life tracers is a very complicated subject that will be partly addressed in this paper. Life leaves traces by modifying microscopically or macroscopically the physical-chemical characteristics of its environment. The extent to which these modifications occur and ...
possible disintegrating short-period super
... transits of a single planet with a fixed size. We discuss but dismiss a scenario involving a binary giant planet whose mutual orbit plane precesses, bringing one of the planets into and out of a grazing transit. This scenario seems ruled out by the dynamical instability that would result from such a ...
... transits of a single planet with a fixed size. We discuss but dismiss a scenario involving a binary giant planet whose mutual orbit plane precesses, bringing one of the planets into and out of a grazing transit. This scenario seems ruled out by the dynamical instability that would result from such a ...
Session 1: Stellar winds, diagnostics across the electromagnetic
... Detectable radio emission occurs during all phases of massive star evolution.I will concentrate on the thermal and non-thermal continuum emission from early-type stars. The thermal radio emission is due to free-free interactions in the ionized stellar wind material. Early ideas that this would lead ...
... Detectable radio emission occurs during all phases of massive star evolution.I will concentrate on the thermal and non-thermal continuum emission from early-type stars. The thermal radio emission is due to free-free interactions in the ionized stellar wind material. Early ideas that this would lead ...
Infrared Photometry of Red Supergiants in Young Clusters in the
... could RSGs be produced at low metallicities. They used the luminosity difference between the blue and RSGs to rule out significant amounts of convective core overshoot (d/Hp<0.2). In the study of NGC 330 by Chiosi et al (1995) it was shown that with new opacities and input physics it was possible to ...
... could RSGs be produced at low metallicities. They used the luminosity difference between the blue and RSGs to rule out significant amounts of convective core overshoot (d/Hp<0.2). In the study of NGC 330 by Chiosi et al (1995) it was shown that with new opacities and input physics it was possible to ...
FINAL STAGES OF MASSIVE STARS. SN EXPLOSION AND
... Explosion Mechanism Still Uncertain The explosive nucleosynthesis calculations for core collapse supernovae are still based on explosions induced by injecting an arbitrary amount of energy in a (also arbitrary) mass location of the presupernova model and then following the development of the blast w ...
... Explosion Mechanism Still Uncertain The explosive nucleosynthesis calculations for core collapse supernovae are still based on explosions induced by injecting an arbitrary amount of energy in a (also arbitrary) mass location of the presupernova model and then following the development of the blast w ...
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.