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Gaillard_Scaillet_volcanic_deg
... already oxidized mantle (Trail et al., 2011), that magma degassing began to significantly impact the atmosphere (Gaillard et al., 2013; Fig.1). We consider that this degassing results from basalts formed by partial melting of a mantle that has already ingested the late veneer. This is the starting p ...
... already oxidized mantle (Trail et al., 2011), that magma degassing began to significantly impact the atmosphere (Gaillard et al., 2013; Fig.1). We consider that this degassing results from basalts formed by partial melting of a mantle that has already ingested the late veneer. This is the starting p ...
An Estimate of the Age Distribution of Terrestrial Planets in the
... Planets such as the Earth cannot form unless elements heavier than helium are available. These heavy elements, or “metals,” were not produced in the Big Bang. They result from fusion inside stars and have been gradually building up over the lifetime of the Universe. Recent observations indicate that ...
... Planets such as the Earth cannot form unless elements heavier than helium are available. These heavy elements, or “metals,” were not produced in the Big Bang. They result from fusion inside stars and have been gradually building up over the lifetime of the Universe. Recent observations indicate that ...
Star formation and the interstellar medium in galaxy
... to have temperatures between 10 and 106 K, although these high temperatures are never reached (we do not yet include supernovae that could produce them). We use a Jeans instability condition to localize star forming regions, and scale the collapse time for an unstable region directly to the free-fal ...
... to have temperatures between 10 and 106 K, although these high temperatures are never reached (we do not yet include supernovae that could produce them). We use a Jeans instability condition to localize star forming regions, and scale the collapse time for an unstable region directly to the free-fal ...
L53 He I 1.083 mm EMISSION AND ABSORPTION IN DG TAURI
... and [N ii] l6583, whose excitation energies are typically 2 eV from the ground. On the other hand, the He i 1.083 mm emission has an excitation energy of 20 eV, about ∼10 times larger. This line has been observed in some high-velocity Herbig-Haro objects (e.g., Brugel, Böhm, & Mannery 1981) and in ...
... and [N ii] l6583, whose excitation energies are typically 2 eV from the ground. On the other hand, the He i 1.083 mm emission has an excitation energy of 20 eV, about ∼10 times larger. This line has been observed in some high-velocity Herbig-Haro objects (e.g., Brugel, Böhm, & Mannery 1981) and in ...
The Milky Way and Andromeda galaxies in a constrained
... with L(t) being the UV-luminosity of the stellar population and τIR an infrared optical depth that depends on the density, metallicity, and velocity dispersion of the gas around the star. This last dependency makes the effects of radiation pressure larger in systems with higher velocity dispersions, ...
... with L(t) being the UV-luminosity of the stellar population and τIR an infrared optical depth that depends on the density, metallicity, and velocity dispersion of the gas around the star. This last dependency makes the effects of radiation pressure larger in systems with higher velocity dispersions, ...
Cosmological dynamics with non-minimally coupled scalar field and
... example from the quantum field theory in curved spacetime. f ( R) theories are also widely used as an alternative explanation of the dark energy phenomena which places them amongst the most popular and widely explored alternative theories of gravity. Most of the studies on f ( R) theories though are ...
... example from the quantum field theory in curved spacetime. f ( R) theories are also widely used as an alternative explanation of the dark energy phenomena which places them amongst the most popular and widely explored alternative theories of gravity. Most of the studies on f ( R) theories though are ...
Chapter 9 Early stages of evolution and the main sequence phase
... The process of star formation constitutes one of the main problems of modern astrophysics. Compared to our understanding of what happens after stars have formed out of the interstellar medium – that is, stellar evolution – star formation is a very ill-understood problem. No predictive theory of star ...
... The process of star formation constitutes one of the main problems of modern astrophysics. Compared to our understanding of what happens after stars have formed out of the interstellar medium – that is, stellar evolution – star formation is a very ill-understood problem. No predictive theory of star ...
Detection and characterization of extrasolar planets: the
... The three equations describing a planetary transit (depth, total duration and ingress duration), can be used to constrain four unknown parameters of the system: r, R, M, b. The star’s mass and radius may be independently constrained by other observations, specifically highresolution spectroscopy, as ...
... The three equations describing a planetary transit (depth, total duration and ingress duration), can be used to constrain four unknown parameters of the system: r, R, M, b. The star’s mass and radius may be independently constrained by other observations, specifically highresolution spectroscopy, as ...
Galaxy Notes
... from the central bulge. The Milky Way is a spiral galaxy. Like pinwheels, all spiral galaxies rotate -- but slowly. The Milky Way, for example, makes a complete revolution once every 250 million years or so. New stars are constantly forming out of gas and dust in spiral galaxies. Smaller groups of s ...
... from the central bulge. The Milky Way is a spiral galaxy. Like pinwheels, all spiral galaxies rotate -- but slowly. The Milky Way, for example, makes a complete revolution once every 250 million years or so. New stars are constantly forming out of gas and dust in spiral galaxies. Smaller groups of s ...
Boron Abundances Across the" Li
... Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program #HST-G0-12294. ...
... Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program #HST-G0-12294. ...
Potential for Life on the Terrestrial Planets
... tens to hundreds of bars of atmospheric pressure, or even their whole atmospheres due to the CME-induced O+ ion pick up at orbital distances ≤ 0.2 AU. We have found that atmospheres with CO2/N2 mixing ratios lower then 96% and exposed to intense XUV fluxes result in higher exospheric temperatures an ...
... tens to hundreds of bars of atmospheric pressure, or even their whole atmospheres due to the CME-induced O+ ion pick up at orbital distances ≤ 0.2 AU. We have found that atmospheres with CO2/N2 mixing ratios lower then 96% and exposed to intense XUV fluxes result in higher exospheric temperatures an ...
arXiv:1210.2471v1 [astro-ph.EP] 9 Oct 2012 Exoplanet Detection
... of the parent star. Although the emission of exoplanets is indeed quite faint, it is generally the problem of detecting this emission in the proximity of the much brighter stellar source that presents the most severe practical obstacle to direct detection. The disentangling of stellar and planetary ...
... of the parent star. Although the emission of exoplanets is indeed quite faint, it is generally the problem of detecting this emission in the proximity of the much brighter stellar source that presents the most severe practical obstacle to direct detection. The disentangling of stellar and planetary ...
Variable stars in the globular cluster M 92
... Abstract. Results of a search for variable stars in the central region of the Oosterhoff II type globular cluster M 92 are presented. Out of the 28 variable and suspected variable stars listed in the Catalogue of Variable Stars in Globular Clusters (Clement 1997) only two were not observed. Surprisi ...
... Abstract. Results of a search for variable stars in the central region of the Oosterhoff II type globular cluster M 92 are presented. Out of the 28 variable and suspected variable stars listed in the Catalogue of Variable Stars in Globular Clusters (Clement 1997) only two were not observed. Surprisi ...
Identifying Young far from Giant Stars Molecular Clouds
... features to the stellar spectra. When this boundary material heats up as it accretes onto the star, it radiates, contributing its own continuum to the stellar spectrum. When the material is heated, the electrons in the layer's hydrogen atoms are excited to higher energy levels. However, the electron ...
... features to the stellar spectra. When this boundary material heats up as it accretes onto the star, it radiates, contributing its own continuum to the stellar spectrum. When the material is heated, the electrons in the layer's hydrogen atoms are excited to higher energy levels. However, the electron ...
Forming Jupiter, Saturn, Uranus and Neptune in few million years by
... the planetesimal mass lies in kilometer-sized bodies, the formation time of the ice giants results much longer than the estimated lifetime of the protoplanetary disk. In order to evaluate the effects of the above mentioned inhibition on the solids accretion rate, we also computed the growth of the f ...
... the planetesimal mass lies in kilometer-sized bodies, the formation time of the ice giants results much longer than the estimated lifetime of the protoplanetary disk. In order to evaluate the effects of the above mentioned inhibition on the solids accretion rate, we also computed the growth of the f ...
Massive Star Formation in the Galactic Center
... mass, M≈104 M , and relatively young age, τ = 2 M yr (Figer et al. 2002). Being so young and massive, it contains the richest collection of O-stars and WNL stars in any cluster in the Galaxy (Cotera et al. 1996; Serabyn, Shupe, & Figer 1998; Figer et al. 1999b; Blum et al. 2001; Figer et al. 2002). ...
... mass, M≈104 M , and relatively young age, τ = 2 M yr (Figer et al. 2002). Being so young and massive, it contains the richest collection of O-stars and WNL stars in any cluster in the Galaxy (Cotera et al. 1996; Serabyn, Shupe, & Figer 1998; Figer et al. 1999b; Blum et al. 2001; Figer et al. 2002). ...
THE DEARTH OF UV-BRIGHT STARS IN M32
... useful testing ground for stellar evolution theory. With solarblind ultraviolet (UV) observations that suppress the dominant cool population, hot stars in late evolutionary phases can be resolved into the center of the galaxy. From such observations one can construct a UV color-magnitude diagram (CM ...
... useful testing ground for stellar evolution theory. With solarblind ultraviolet (UV) observations that suppress the dominant cool population, hot stars in late evolutionary phases can be resolved into the center of the galaxy. From such observations one can construct a UV color-magnitude diagram (CM ...
Magnetic Fields in Stars
... small wavelength difference between the two sets of σ components. The presence of a field can be detected by this shift in the position of spectral lines between spectra observed in right- and left-circularly polarized light, or equivalently in the spectrum formed by the difference of the two spectr ...
... small wavelength difference between the two sets of σ components. The presence of a field can be detected by this shift in the position of spectral lines between spectra observed in right- and left-circularly polarized light, or equivalently in the spectrum formed by the difference of the two spectr ...
Radial velocity planet detection biases at the stellar rotational period
... orbits with RV semi-amplitudes half the typical amplitude of the stellar activity signal and with randomly distributed orbital phases. After generating the simulated RV time series, we began analysis to attempt to mitigate the stellar RV signal and recover the planets. We fit a line to the measured ...
... orbits with RV semi-amplitudes half the typical amplitude of the stellar activity signal and with randomly distributed orbital phases. After generating the simulated RV time series, we began analysis to attempt to mitigate the stellar RV signal and recover the planets. We fit a line to the measured ...
The deep OB star population in Carina from the VST Photometric Hα
... The number of objects in this initial selection was 37 971. All candidates are then cross-matched against the Two Micron All-Sky Survey (2MASS), the only available near-infrared (NIR) survey covering the whole region. The maximum cross-match distance was set to 1 arcsec in forming optical near-infra ...
... The number of objects in this initial selection was 37 971. All candidates are then cross-matched against the Two Micron All-Sky Survey (2MASS), the only available near-infrared (NIR) survey covering the whole region. The maximum cross-match distance was set to 1 arcsec in forming optical near-infra ...
Chemical composition of halo and disk stars with
... groups were defined according to the criteria: i) Vrot < 50 km s−1 ; the halo stars. ii) Vrot > 150 km s−1 ; the disk stars. We aimed at observing about the same number of halo and disk stars, and furthermore to have as far as possible the same distribution in [Fe/H] for the two groups. Obviously, o ...
... groups were defined according to the criteria: i) Vrot < 50 km s−1 ; the halo stars. ii) Vrot > 150 km s−1 ; the disk stars. We aimed at observing about the same number of halo and disk stars, and furthermore to have as far as possible the same distribution in [Fe/H] for the two groups. Obviously, o ...
PDF only
... to the nature of the companion star in the system (from Ref. [3-b]). (b) Measured surface temperatures of isolated neutron stars; the ages reported in abscissa are obtained from the rotating dipole model, and the solid line represents a standard cooling simulation (from Ref. [6-b]). We thus see how ...
... to the nature of the companion star in the system (from Ref. [3-b]). (b) Measured surface temperatures of isolated neutron stars; the ages reported in abscissa are obtained from the rotating dipole model, and the solid line represents a standard cooling simulation (from Ref. [6-b]). We thus see how ...
Reprocessing the Hipparcos data of evolved stars
... Hipparcos mission. The parallaxes are in most cases re-computed from the Hipparcos Intermediate Astrometric Data using improved astrometric fits and chromaticity corrections. The K band magnitudes are taken from the literature and from measurements by COBE, and are corrected for interstellar and cir ...
... Hipparcos mission. The parallaxes are in most cases re-computed from the Hipparcos Intermediate Astrometric Data using improved astrometric fits and chromaticity corrections. The K band magnitudes are taken from the literature and from measurements by COBE, and are corrected for interstellar and cir ...
Symbiotic Stars as Laboratories for the Study of
... from the nebula that require the presence of a hot source of ionizing radiation. These combination spectra are the reason symbiotic stars were originally called “symbiotic”. Spectral features indicating the presence of two very different types of environments in the same object made these objects se ...
... from the nebula that require the presence of a hot source of ionizing radiation. These combination spectra are the reason symbiotic stars were originally called “symbiotic”. Spectral features indicating the presence of two very different types of environments in the same object made these objects se ...
Comets review.fm - Journals at the University of Arizona
... processes that occurred in the outer part of the protoplanetary nebula because they are a mixture of interstellar and processed solar material (see the chapter by Ehrenfreund et al.). For example, the fifth part of the book shows that the composition of cometary volatiles provides direct information ...
... processes that occurred in the outer part of the protoplanetary nebula because they are a mixture of interstellar and processed solar material (see the chapter by Ehrenfreund et al.). For example, the fifth part of the book shows that the composition of cometary volatiles provides direct information ...
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.