Krypton in presolar mainstream SiC grains from AGB stars
... and the light noble gases (Lewis et al. 1990, 1994) and also with analysis of the xenon implantation energy in the grains (Verchovsky et al. 2004). In this paper we want to analyse the Kr−G component in mainstream SiC grains. For a detailed description of the s−process in AGB stars see Gallino et al ...
... and the light noble gases (Lewis et al. 1990, 1994) and also with analysis of the xenon implantation energy in the grains (Verchovsky et al. 2004). In this paper we want to analyse the Kr−G component in mainstream SiC grains. For a detailed description of the s−process in AGB stars see Gallino et al ...
Puzzling X-rays from the new colliding wind binary Wolf–Rayet 65
... image. Except for WR 65, there are no other known objects at this position. WR 65 is a probable member of the cluster Pismis 20, which contains one more WR star, WR 67, and has a distance of d = 3272 ± 303 pc (Turner 1996). We fit the optical spectrum of WR 65 and its available photometry using the ...
... image. Except for WR 65, there are no other known objects at this position. WR 65 is a probable member of the cluster Pismis 20, which contains one more WR star, WR 67, and has a distance of d = 3272 ± 303 pc (Turner 1996). We fit the optical spectrum of WR 65 and its available photometry using the ...
Non-thermal hard X-ray emission from stellar coronae
... Ilgner & Nelson (2006) What the role of hard X-rays during flares, ...
... Ilgner & Nelson (2006) What the role of hard X-rays during flares, ...
The density of very massive evolved galaxies to z≃ 1.7
... The density of massive early types to z 1.7 break of galaxies at z < 1.2. We find that, at the average redshift z max 1.55, the seven massive early types account for a co-moving density ρ = (5.5 ± 2) × 10−5 Mpc−3 over a volume of about 1.5 × 105 Mpc3 . Given the stellar masses of the seven e ...
... The density of massive early types to z 1.7 break of galaxies at z < 1.2. We find that, at the average redshift z max 1.55, the seven massive early types account for a co-moving density ρ = (5.5 ± 2) × 10−5 Mpc−3 over a volume of about 1.5 × 105 Mpc3 . Given the stellar masses of the seven e ...
the origin of binary stars - Institut d`Astronomie et d`Astrophysique
... core “passes the brink of instability” (Shu et al. 1987) and collapses dynamically toward stellar densities. This leads to the formation of a central protostar embedded within an infalling envelope of dust and gas. A disk almost always surrounds the embedded protostar, reflecting the fact that molec ...
... core “passes the brink of instability” (Shu et al. 1987) and collapses dynamically toward stellar densities. This leads to the formation of a central protostar embedded within an infalling envelope of dust and gas. A disk almost always surrounds the embedded protostar, reflecting the fact that molec ...
Star Clusters - Caltech Astronomy
... Open clusters Some 1200 open clusters have been catalogued, but as many as 250 of these appear to be simply slight enhancements in the stellar density along a line of sight or small asterisms of unrelated stars. Such asterisms should not be considered as clusters by either of the definitions of clus ...
... Open clusters Some 1200 open clusters have been catalogued, but as many as 250 of these appear to be simply slight enhancements in the stellar density along a line of sight or small asterisms of unrelated stars. Such asterisms should not be considered as clusters by either of the definitions of clus ...
astro-ph/9505110 PDF
... in our Galaxy is decoupled from that of carbon and oxygen. One possible interpretation of the trend in C/O is that the most metal-poor galaxies are young and dominated by the products of early enrichment by massive stars, while more metal-rich galaxies show increasing, delayed contributions of carbo ...
... in our Galaxy is decoupled from that of carbon and oxygen. One possible interpretation of the trend in C/O is that the most metal-poor galaxies are young and dominated by the products of early enrichment by massive stars, while more metal-rich galaxies show increasing, delayed contributions of carbo ...
Research paper
... −100 to +120 km s−1 ; Figure 3 shows a moment 0 image over the same radial velocity range. Figure 4 shows a color version of the maximum temperature from VLSR = −100 to 0 km s−1 in blue and from VLSR = 20 to 120 km s−1 in red. The maximum brightness temperature better illustrates the relatively cons ...
... −100 to +120 km s−1 ; Figure 3 shows a moment 0 image over the same radial velocity range. Figure 4 shows a color version of the maximum temperature from VLSR = −100 to 0 km s−1 in blue and from VLSR = 20 to 120 km s−1 in red. The maximum brightness temperature better illustrates the relatively cons ...
- StealthSkater
... End of the Universe (whatever that might be). With all these facts at hand, we're now ready to tackle the first part of the detective story. Let's suppose we wanted to make out own map of a trip to the stars. We will limit ourselves to the 55 light-year radius covered by the detailed star catalogs. ...
... End of the Universe (whatever that might be). With all these facts at hand, we're now ready to tackle the first part of the detective story. Let's suppose we wanted to make out own map of a trip to the stars. We will limit ourselves to the 55 light-year radius covered by the detailed star catalogs. ...
transparencies - Rencontres du Vietnam
... MACHO-A-LMC#5 : galactic red dwarf lens MACHO-A-LMC#6 MACHO-A-LMC#7 MACHO-A-LMC#8 MACHO-A-LMC#13 MACHO-A-LMC#14 : self-lensing MACHO-A-LMC#15 MACHO-A-LMC#18 MACHO-A-LMC#21 MACHO-A-LMC#23 : Variable star MACHO-A-LMC#25 ...
... MACHO-A-LMC#5 : galactic red dwarf lens MACHO-A-LMC#6 MACHO-A-LMC#7 MACHO-A-LMC#8 MACHO-A-LMC#13 MACHO-A-LMC#14 : self-lensing MACHO-A-LMC#15 MACHO-A-LMC#18 MACHO-A-LMC#21 MACHO-A-LMC#23 : Variable star MACHO-A-LMC#25 ...
ph709-15
... 2) Stellar metallicity associted with jupiter-sized planets correlates strongly with the presence of planets. Sample exhibits a planet-metallicity correlation at all stellar masses; this argues that the high metallicities of stars with planets is not likely due to convective envelope "pollution." BU ...
... 2) Stellar metallicity associted with jupiter-sized planets correlates strongly with the presence of planets. Sample exhibits a planet-metallicity correlation at all stellar masses; this argues that the high metallicities of stars with planets is not likely due to convective envelope "pollution." BU ...
Open clusters in the Third Galactic Quadrant III. Alleged binary
... members, some sequences are not satisfactorily reproduced by one single isochrone, as said above, and a range of them has been indicated in each cluster of Table 4. Known reasons to fail the fitting include the effect of un-resolved binaries, stellar rotation and variable reddening due to remaining m ...
... members, some sequences are not satisfactorily reproduced by one single isochrone, as said above, and a range of them has been indicated in each cluster of Table 4. Known reasons to fail the fitting include the effect of un-resolved binaries, stellar rotation and variable reddening due to remaining m ...
An Estimate of the Age Distribution of Terrestrial Planets in the
... We cannot yet verify if our Solar System is a typical planetary system or how generic the pattern described above is. The Doppler technique responsible for almost all extrasolar planet detections (Mayor and Queloz 1995, Butler et al. 2000 and references therein) is most sensitive to massive close-or ...
... We cannot yet verify if our Solar System is a typical planetary system or how generic the pattern described above is. The Doppler technique responsible for almost all extrasolar planet detections (Mayor and Queloz 1995, Butler et al. 2000 and references therein) is most sensitive to massive close-or ...
Chapter 7 in the LSST Science Book
... interpretation of local data within a larger context: the stars that make galaxies are expected to form within dark matter halos that are themselves growing through gravitational collapse and mergers. In fact, we are very fortunate to live in a hierarchical Universe where the LV galaxies contain the ...
... interpretation of local data within a larger context: the stars that make galaxies are expected to form within dark matter halos that are themselves growing through gravitational collapse and mergers. In fact, we are very fortunate to live in a hierarchical Universe where the LV galaxies contain the ...
The MGC - St Andrews Astronomy Group
... The Hubble Tuning Fork Breakdown • Numerous new galaxy types have been found which do not fit on the original Hubble tuning fork diagram ...
... The Hubble Tuning Fork Breakdown • Numerous new galaxy types have been found which do not fit on the original Hubble tuning fork diagram ...
Stellar evolution
Stellar evolution is the process by which a star changes during its lifetime. Depending on the mass of the star, this lifetime ranges from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the age of the universe. The table shows the lifetimes of stars as a function of their masses. All stars are born from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main-sequence star.Nuclear fusion powers a star for most of its life. Initially the energy is generated by the fusion of hydrogen atoms at the core of the main-sequence star. Later, as the preponderance of atoms at the core becomes helium, stars like the Sun begin to fuse hydrogen along a spherical shell surrounding the core. This process causes the star to gradually grow in size, passing through the subgiant stage until it reaches the red giant phase. Stars with at least half the mass of the Sun can also begin to generate energy through the fusion of helium at their core, whereas more-massive stars can fuse heavier elements along a series of concentric shells. Once a star like the Sun has exhausted its nuclear fuel, its core collapses into a dense white dwarf and the outer layers are expelled as a planetary nebula. Stars with around ten or more times the mass of the Sun can explode in a supernova as their inert iron cores collapse into an extremely dense neutron star or black hole. Although the universe is not old enough for any of the smallest red dwarfs to have reached the end of their lives, stellar models suggest they will slowly become brighter and hotter before running out of hydrogen fuel and becoming low-mass white dwarfs.Stellar evolution is not studied by observing the life of a single star, as most stellar changes occur too slowly to be detected, even over many centuries. Instead, astrophysicists come to understand how stars evolve by observing numerous stars at various points in their lifetime, and by simulating stellar structure using computer models.In June 2015, astronomers reported evidence for Population III stars in the Cosmos Redshift 7 galaxy at z = 6.60. Such stars are likely to have existed in the very early universe (i.e., at high redshift), and may have started the production of chemical elements heavier than hydrogen that are needed for the later formation of planets and life as we know it.