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A FUSE Survey of Coronal Forbidden Lines in Late
... We searched for evidence of coronal forbidden lines in the 900–1200 Å region in our sample of stellar spectra. Because of our relatively poor knowledge of the rest wavelengths of these lines, the relatively weak signal of the coronal lines, and the moderate likelihood of coincidental blends with lo ...
... We searched for evidence of coronal forbidden lines in the 900–1200 Å region in our sample of stellar spectra. Because of our relatively poor knowledge of the rest wavelengths of these lines, the relatively weak signal of the coronal lines, and the moderate likelihood of coincidental blends with lo ...
Detecting Stars at the Galactic Centre via Synchrotron Emission
... detectable via thermal emission, we have shown that stars such as S2 may be detectable via synchrotron emission. Figure 1 shows that the contrast of synchrotron flux relative to Sgr A* is maximized around the 1.4 GHz band. However, due to scattering we will need to use a higher frequency, around 10 ...
... detectable via thermal emission, we have shown that stars such as S2 may be detectable via synchrotron emission. Figure 1 shows that the contrast of synchrotron flux relative to Sgr A* is maximized around the 1.4 GHz band. However, due to scattering we will need to use a higher frequency, around 10 ...
the mass-loss return from evolved stars to the large
... We model multi-wavelength broadband UBVIJHKs and Spitzer IRAC and MIPS photometry and Infrared Spectrograph spectra from the SAGE and SAGE-Spectroscopy observing programs of two oxygen-rich asymptotic giant branch (O-rich AGB) stars in the Large Magellanic Cloud (LMC) using radiative transfer (RT) m ...
... We model multi-wavelength broadband UBVIJHKs and Spitzer IRAC and MIPS photometry and Infrared Spectrograph spectra from the SAGE and SAGE-Spectroscopy observing programs of two oxygen-rich asymptotic giant branch (O-rich AGB) stars in the Large Magellanic Cloud (LMC) using radiative transfer (RT) m ...
Gamma-Ray Bursts
... star explodes in a supernova explosion. The core collapses into a neutron star, and the rest of the star explodes in a supernova explosion. The core collapses into a white dwarf, and the rest of the star explodes to form a planetary nebula. The core collapses into a neutron star, and the rest of the ...
... star explodes in a supernova explosion. The core collapses into a neutron star, and the rest of the star explodes in a supernova explosion. The core collapses into a white dwarf, and the rest of the star explodes to form a planetary nebula. The core collapses into a neutron star, and the rest of the ...
Chapter 1
... As was mentioned earlier, the main source of ionization for producing strong emission lines in star-forming galaxies is very massive stars. However, our knowledge about these massive stars is limited because direct observations of them often cannot be carried out as these stars are often heavily ens ...
... As was mentioned earlier, the main source of ionization for producing strong emission lines in star-forming galaxies is very massive stars. However, our knowledge about these massive stars is limited because direct observations of them often cannot be carried out as these stars are often heavily ens ...
Article (Published version) - Archive ouverte UNIGE
... Measurements were obtained with the cross-dispersed echelle ELODIE spectrograph mounted on the 1.93-m telescope at the Observatoire de Haute-Provence observatory (OHP, France) between late 1993 and mid 2006 (Baranne et al. 1996). The stars were subsequently monitored by the SOPHIE spectrograph that ...
... Measurements were obtained with the cross-dispersed echelle ELODIE spectrograph mounted on the 1.93-m telescope at the Observatoire de Haute-Provence observatory (OHP, France) between late 1993 and mid 2006 (Baranne et al. 1996). The stars were subsequently monitored by the SOPHIE spectrograph that ...
ongoing massive star formation in the bulge of m511 hjglm lamers,2
... best model is found for a relative orbit that is almost in the plane of M51, for a mass ratio of NGC 5194/5195 ^ 2, a pericenter distance of 17È20 kpc, and a time since pericenter of 2.5 ] 108 yr \ t \ 4 ] 108 yr (Barnes 1998). The NGC 5194/5195 system is ideally suited for the study of triggered st ...
... best model is found for a relative orbit that is almost in the plane of M51, for a mass ratio of NGC 5194/5195 ^ 2, a pericenter distance of 17È20 kpc, and a time since pericenter of 2.5 ] 108 yr \ t \ 4 ] 108 yr (Barnes 1998). The NGC 5194/5195 system is ideally suited for the study of triggered st ...
and galaxies
... •Density in such clouds ~ 102-7 atoms /cm3 (c.f. sea level earth atmosphere ~3x1019 /cm3). •Gas is mostly molecular hydrogen, H2…(ISM gas is mostly H-II, i.e., ionised H2 mols). •Note that the H2 molecule does NOT emit the 21cm line. Thus hard to identify in visible region (use rotational decays)…al ...
... •Density in such clouds ~ 102-7 atoms /cm3 (c.f. sea level earth atmosphere ~3x1019 /cm3). •Gas is mostly molecular hydrogen, H2…(ISM gas is mostly H-II, i.e., ionised H2 mols). •Note that the H2 molecule does NOT emit the 21cm line. Thus hard to identify in visible region (use rotational decays)…al ...
An asymmetry detected in the disk of κ CMa⋆ with the AMBER/VLTI
... by frame multiplied by the flux) and the estimated fluxes from each telescope. The principles of the general AMBER data reduction are described in more detail by Millour et al. (2004) and Tatulli et al. (2006). The complex coherent flux allows one to compute differential phase, i.e. the averaged ins ...
... by frame multiplied by the flux) and the estimated fluxes from each telescope. The principles of the general AMBER data reduction are described in more detail by Millour et al. (2004) and Tatulli et al. (2006). The complex coherent flux allows one to compute differential phase, i.e. the averaged ins ...
How plausible are the proposed formation scenarios of CEMP
... stars raises with decreasing metallicity, from three percent at [Fe/H] < −1 up to about 80% at [Fe/H] < −4 (e.g. Cohen et al. 2005; Marsteller et al. 2005; Frebel et al. 2006; Lucatello et al. 2006; Lee et al. 2013; Yong et al. 2013; Placco et al. 2014). Aoki et al. (2007) show that at least 80% of ...
... stars raises with decreasing metallicity, from three percent at [Fe/H] < −1 up to about 80% at [Fe/H] < −4 (e.g. Cohen et al. 2005; Marsteller et al. 2005; Frebel et al. 2006; Lucatello et al. 2006; Lee et al. 2013; Yong et al. 2013; Placco et al. 2014). Aoki et al. (2007) show that at least 80% of ...
REVIEW Numerical Star-Formation Studies— A Status Report
... system reflect the light from our Sun, while virtually every other source of visible light further away is a star or collection of stars. Throughout the millenia, these objects have been the observational targets of traditional astronomy, and define the celestial landscape, the constellations. The mos ...
... system reflect the light from our Sun, while virtually every other source of visible light further away is a star or collection of stars. Throughout the millenia, these objects have been the observational targets of traditional astronomy, and define the celestial landscape, the constellations. The mos ...
Planetary detection limits taking into account stellar noise
... In this paper, we study different observational strategies to average out as much as possible the effect of stellar noise on RV measurements. The main goal is to find a strategy capable of detecting very small mass planets in habitable regions. To be able to search for such long-period planets, observ ...
... In this paper, we study different observational strategies to average out as much as possible the effect of stellar noise on RV measurements. The main goal is to find a strategy capable of detecting very small mass planets in habitable regions. To be able to search for such long-period planets, observ ...
Bright 22 μm excess candidates from the wise all-sky
... better than 0.08, 0.11, 1, and 6 mJy in the four bands in unconfused regions on the ecliptic plane (Wright et al. 2010). The all-sky data were released on 2012 March 14 and they include all the data taken during the WISE full cryogenic mission phase, from 2010 January 7 to 2010 August 6, which were ...
... better than 0.08, 0.11, 1, and 6 mJy in the four bands in unconfused regions on the ecliptic plane (Wright et al. 2010). The all-sky data were released on 2012 March 14 and they include all the data taken during the WISE full cryogenic mission phase, from 2010 January 7 to 2010 August 6, which were ...
Anisotropy of the Hectometer Cosmic Radio Background
... After such a correction for the effect of interfering emissions along the Earth–Sun line, the sought-for quantities m and Lmax at 260 kHz showed a satisfactory stability from session to session, which, in particular, justifies our assumptions. The decrease of the observed modulation index in the Dec ...
... After such a correction for the effect of interfering emissions along the Earth–Sun line, the sought-for quantities m and Lmax at 260 kHz showed a satisfactory stability from session to session, which, in particular, justifies our assumptions. The decrease of the observed modulation index in the Dec ...
chemical abundances for a-and f-type supergiant stars
... and return their chemical elements to the interstellar medium by stellar winds and supernova events. The existence of massive young objects in the galactic plane is not surprising, since it is an area of star formation. These objects are visually luminous in galaxies and thus are suitable candidates ...
... and return their chemical elements to the interstellar medium by stellar winds and supernova events. The existence of massive young objects in the galactic plane is not surprising, since it is an area of star formation. These objects are visually luminous in galaxies and thus are suitable candidates ...
Blue horizontal branch stars in the Sloan Digital Sky Survey:
... 0.8 < u − g < 1.35, −0.4 < g − r < 0.0. The boundaries of this selection box are similar to those used by Yanny & Newberg et al. (2000), and figure 8 (see §5) shows that our final sample of bright BHB stars is well contained within the boundaries. Stars that lie in this region of color-color space p ...
... 0.8 < u − g < 1.35, −0.4 < g − r < 0.0. The boundaries of this selection box are similar to those used by Yanny & Newberg et al. (2000), and figure 8 (see §5) shows that our final sample of bright BHB stars is well contained within the boundaries. Stars that lie in this region of color-color space p ...
Two families of exocomets in the Beta Pictoris system
... The young planetary system surrounding the star β Pictoris harbors active minor bodies 1–6 . These asteroids and comets produce a large amount of dust and gas through collisions and evaporation, as in the early ages of the Solar System 7 . Spectroscopic observations of β Pictoris reveal a high rate ...
... The young planetary system surrounding the star β Pictoris harbors active minor bodies 1–6 . These asteroids and comets produce a large amount of dust and gas through collisions and evaporation, as in the early ages of the Solar System 7 . Spectroscopic observations of β Pictoris reveal a high rate ...
Theory of cooling neutron stars versus observations
... (p), electrons (e) and possibly muons. All these particles are strongly degenerate. The inner core extends to the stellar center [to ∼ (10 − 20)ρ0 in most massive stars]. Its composition is very uncertain. It may be the same as in the outer core or essentially different. In particular, hyperons may ...
... (p), electrons (e) and possibly muons. All these particles are strongly degenerate. The inner core extends to the stellar center [to ∼ (10 − 20)ρ0 in most massive stars]. Its composition is very uncertain. It may be the same as in the outer core or essentially different. In particular, hyperons may ...
The Primeval Populations of the Ultra
... [Fe/H]= −2.3; blue curve) and the low extreme of the metallicity distribution in these UFDs ([Fe/H]= −3.2; green curve). It is clear from the comparison that the luminosity of the MS turnoff and SGB in each galaxy is consistent with ancient metal-poor stars. The few stars immediately brighter and bl ...
... [Fe/H]= −2.3; blue curve) and the low extreme of the metallicity distribution in these UFDs ([Fe/H]= −3.2; green curve). It is clear from the comparison that the luminosity of the MS turnoff and SGB in each galaxy is consistent with ancient metal-poor stars. The few stars immediately brighter and bl ...
Extragalactic Globular Cluster Systems
... The globular clusters that were once within the merging protogalaxies are so dense that they survive intact and will orbit freely within the Galaxy. The surviving protogalaxies may be the precursors of the old satellite galaxies, some of which host old globular clusters such as Fornax, whose morphol ...
... The globular clusters that were once within the merging protogalaxies are so dense that they survive intact and will orbit freely within the Galaxy. The surviving protogalaxies may be the precursors of the old satellite galaxies, some of which host old globular clusters such as Fornax, whose morphol ...
Galaxies on Sub-Galactic Scales
... satellite galaxies over the past seven years. It was instrumental in finding examples of the least luminous galaxies we know in the Universe, uncovering apparent inconsistencies between cold dark matter theory and dwarf galaxy properties, providing first evidence for a possible lower mass limit for ...
... satellite galaxies over the past seven years. It was instrumental in finding examples of the least luminous galaxies we know in the Universe, uncovering apparent inconsistencies between cold dark matter theory and dwarf galaxy properties, providing first evidence for a possible lower mass limit for ...
Stellar interactions in dense and sparse star clusters
... do affect the evolution of the protoplanetary discs. With higher cluster density low-mass stars become more heavily involved in this process. These results can also be applied to extreme stellar systems: in the case of the Arches cluster one would expect stellar encounters to destroy the discs of mos ...
... do affect the evolution of the protoplanetary discs. With higher cluster density low-mass stars become more heavily involved in this process. These results can also be applied to extreme stellar systems: in the case of the Arches cluster one would expect stellar encounters to destroy the discs of mos ...
Large-eddy simulations of isolated disc galaxies with thermal and
... our simulations, such as an average star formation efficiency ∼1 per cent, a typical velocity dispersion around ∼ 10 km s−1 in star-forming regions, and an almost linear relationship between the column densities of star formation and dense molecular gas. Key words: methods: numerical - galaxies: ISM ...
... our simulations, such as an average star formation efficiency ∼1 per cent, a typical velocity dispersion around ∼ 10 km s−1 in star-forming regions, and an almost linear relationship between the column densities of star formation and dense molecular gas. Key words: methods: numerical - galaxies: ISM ...
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.