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The Milky Way - Faculty Web Pages
... Astronomers believe that gigantic spherical clusters of stars, called Globular Clusters, each with hundreds of thousands of stars, formed evenly around the center of the Milky Way many billions of years ago. These globular clusters are so large and bright that they can be seen from very far way – mu ...
... Astronomers believe that gigantic spherical clusters of stars, called Globular Clusters, each with hundreds of thousands of stars, formed evenly around the center of the Milky Way many billions of years ago. These globular clusters are so large and bright that they can be seen from very far way – mu ...
Collisions and close encounters involving massive main
... We study close encounters involving massive main-sequence stars and the evolution of the exotic products of these encounters as common-envelope systems or possible hypernova progenitors. We show that parabolic encounters between low- and high-mass stars and between two high-mass stars with small per ...
... We study close encounters involving massive main-sequence stars and the evolution of the exotic products of these encounters as common-envelope systems or possible hypernova progenitors. We show that parabolic encounters between low- and high-mass stars and between two high-mass stars with small per ...
Document
... product of mass and acceleration in your reference frame. (Nonrelativistic version of this statement is Newton’s second law: force = mass times acceleration.) But the mass approaches infinity as V approaches c, and thus an infinite force is required to accelerate it further. There’s no such thing ...
... product of mass and acceleration in your reference frame. (Nonrelativistic version of this statement is Newton’s second law: force = mass times acceleration.) But the mass approaches infinity as V approaches c, and thus an infinite force is required to accelerate it further. There’s no such thing ...
Determining distances to stars statistically from photometry
... calculations about 100 times faster than the CPUs (Desell et al. 2009). It is not easy to parallelize the computation of the integral on BOINC, because that would require communication between the processors, which is not possible at this time. Instead, we parallelize the calculations by sending a s ...
... calculations about 100 times faster than the CPUs (Desell et al. 2009). It is not easy to parallelize the computation of the integral on BOINC, because that would require communication between the processors, which is not possible at this time. Instead, we parallelize the calculations by sending a s ...
An improved classification of B[e]-type stars
... ionization species, e.g. He ii λ4686, [O iii] λ5007, but this is not a defining characteristic. These spectroscopic criteria were defined for the optical spectrum and should not automatically be extended to other wavelength regions. For instance, the ISO − SW S spectrum of many luminous supergiants ...
... ionization species, e.g. He ii λ4686, [O iii] λ5007, but this is not a defining characteristic. These spectroscopic criteria were defined for the optical spectrum and should not automatically be extended to other wavelength regions. For instance, the ISO − SW S spectrum of many luminous supergiants ...
The spectral energy distribution of protoplanetary
... Grellmann et al. (2011) suggest the discovery of the potential first discs around high-mass stars. Both focus on a single disc–star system, the first in the Carina Nebula and the second just north of the Cone Nebula. Both studies fit the model spectral energy distributions (SEDs) from Robitaille et ...
... Grellmann et al. (2011) suggest the discovery of the potential first discs around high-mass stars. Both focus on a single disc–star system, the first in the Carina Nebula and the second just north of the Cone Nebula. Both studies fit the model spectral energy distributions (SEDs) from Robitaille et ...
Young Galaxies Grow - Astronomical Society of the Pacific
... tenuous spiral arms appeared much more extended than seen in visible images of the galaxy. Ultraviolet-bright, thin structures stretch to almost five times the galaxy’s optical radius. ...
... tenuous spiral arms appeared much more extended than seen in visible images of the galaxy. Ultraviolet-bright, thin structures stretch to almost five times the galaxy’s optical radius. ...
REVIEWS The formation of the first stars and galaxies Volker Bromm
... Some of the feedback processes described above that affect the formation of individual stars also influence primordial star formation on large scales. The enormous fluxes of ionizing radiation and H2dissociating Lyman–Werner radiation emitted by massive population III stars27,41 dramatically influen ...
... Some of the feedback processes described above that affect the formation of individual stars also influence primordial star formation on large scales. The enormous fluxes of ionizing radiation and H2dissociating Lyman–Werner radiation emitted by massive population III stars27,41 dramatically influen ...
Transit of Luyten 726-8 within 1 ly from Epsilon Eridani
... (=BL/UV Ceti) will pass at . 0.93 ly from Epsilon Eridani in ≈ 31.5 kyr. So, it will probably pierce through the outer part of the hypothetical Oort cloud of ε Eri. BL/UV Ceti has only about 20 percent of the solar mass. Nevertheless, it could influence directly some long-period comets of Epsilon Er ...
... (=BL/UV Ceti) will pass at . 0.93 ly from Epsilon Eridani in ≈ 31.5 kyr. So, it will probably pierce through the outer part of the hypothetical Oort cloud of ε Eri. BL/UV Ceti has only about 20 percent of the solar mass. Nevertheless, it could influence directly some long-period comets of Epsilon Er ...
The Lagoon Nebula and its Vicinity
... cluster, so NGC 6530 is now always used to refer to the cluster rather than any surrounding nebulosity. We take NGC 6533 to refer to the H II region only, comprising NGC 6523 and 6526. H II region studies have generally concentrated on the brighter eastern core (i.e. NGC 6523), and so it is this des ...
... cluster, so NGC 6530 is now always used to refer to the cluster rather than any surrounding nebulosity. We take NGC 6533 to refer to the H II region only, comprising NGC 6523 and 6526. H II region studies have generally concentrated on the brighter eastern core (i.e. NGC 6523), and so it is this des ...
contributed talk in splinter session
... observations) is as much of a puzzle as the mass accretion rate that they carry. Mass and angular momentum are not only gained by the star in the process of accretion, but also lost in either jets or winds. Linking all these different features is the magnetic field. Recent observations suggest the p ...
... observations) is as much of a puzzle as the mass accretion rate that they carry. Mass and angular momentum are not only gained by the star in the process of accretion, but also lost in either jets or winds. Linking all these different features is the magnetic field. Recent observations suggest the p ...
Ultra faint dwarfs: probing early cosmic star formation
... Galactic Medium (GM), whose metal enrichment strongly depends on the star formation (SF) history and mechanical feedback along the hierarchical tree. The model successfully reproduces the global properties of the MW and the Metallicity Distribution Function (MDF) of Galactic halo stars, along with t ...
... Galactic Medium (GM), whose metal enrichment strongly depends on the star formation (SF) history and mechanical feedback along the hierarchical tree. The model successfully reproduces the global properties of the MW and the Metallicity Distribution Function (MDF) of Galactic halo stars, along with t ...
HOW TO MAKE A SINGLETON sdB STAR VIA ACCELERATED STELLAR... Drew Clausen and Richard A. Wade
... of the binary must be such that the primary evolves to the giant branch and triggers an episode of unstable mass transfer that completely removes its envelope before the merger. Furthermore, the total mass of the merged star must be in the range 0.53–0.84 M for the merged object to evolve into an s ...
... of the binary must be such that the primary evolves to the giant branch and triggers an episode of unstable mass transfer that completely removes its envelope before the merger. Furthermore, the total mass of the merged star must be in the range 0.53–0.84 M for the merged object to evolve into an s ...
Origin and formation of planetary systems
... showed that cores of typically about 10 MEarth are needed to gravitationally bind a comparable amount of nebula gas. Such envelopes were found to continue mass accretion up to a few tens of MEarth if the contraction of their envelopes was calculated for quasi-hydrostatic models (Bodenheimer and Poll ...
... showed that cores of typically about 10 MEarth are needed to gravitationally bind a comparable amount of nebula gas. Such envelopes were found to continue mass accretion up to a few tens of MEarth if the contraction of their envelopes was calculated for quasi-hydrostatic models (Bodenheimer and Poll ...
Chemical tagging of three distinct populations of red giants in the
... two aspects: what were the first generation polluters (either intermediate-mass AGB stars, Ventura et al. 2001, or fast rotating massive stars, FRMS, Decressin et al. 2007), and whether the bursts of star formation for the different stellar generations in GCs represented a continuum or were discrete ...
... two aspects: what were the first generation polluters (either intermediate-mass AGB stars, Ventura et al. 2001, or fast rotating massive stars, FRMS, Decressin et al. 2007), and whether the bursts of star formation for the different stellar generations in GCs represented a continuum or were discrete ...
Constellations
... In the United States, during the nineteenth century, AfricanAmericans that were being held as slaves in the south made use of the Big Dipper’s consistent northern sky location. The Big Dipper was also known as the Drinking Gourd and slaves trying to make their way to freedom used it as a guidepost t ...
... In the United States, during the nineteenth century, AfricanAmericans that were being held as slaves in the south made use of the Big Dipper’s consistent northern sky location. The Big Dipper was also known as the Drinking Gourd and slaves trying to make their way to freedom used it as a guidepost t ...
Optical studies of an ultraluminous X-ray source: NGC1313 X-2 Jifeng Liu
... Optical studies of an ultraluminous X-ray source: NGC1313 X-2 Jifeng Liu Harvard-Smithsonian Center for Astrophysics in collaboration with Joel Bregman, Jon Miller, Philip Kaaret ...
... Optical studies of an ultraluminous X-ray source: NGC1313 X-2 Jifeng Liu Harvard-Smithsonian Center for Astrophysics in collaboration with Joel Bregman, Jon Miller, Philip Kaaret ...
The Sagittarius dwarf irregular galaxy: Metallicity and stellar
... Hii regions were investigated by Strobel et al. (1991), who detected 3 regions in their 2.0 5 square field. High-resolution, high sensitivity VLA observations of the SagDIG Hi content have been obtained by Young & Lo (1997) (see also Lo et al. 1993). About 1.2 × 107 M of H+He have been estimated (u ...
... Hii regions were investigated by Strobel et al. (1991), who detected 3 regions in their 2.0 5 square field. High-resolution, high sensitivity VLA observations of the SagDIG Hi content have been obtained by Young & Lo (1997) (see also Lo et al. 1993). About 1.2 × 107 M of H+He have been estimated (u ...
The Sagittarius dwarf irregular galaxy: Metallicity and stellar
... Hii regions were investigated by Strobel et al. (1991), who detected 3 regions in their 2.0 5 square field. High-resolution, high sensitivity VLA observations of the SagDIG Hi content have been obtained by Young & Lo (1997) (see also Lo et al. 1993). About 1.2 × 107 M of H+He have been estimated (u ...
... Hii regions were investigated by Strobel et al. (1991), who detected 3 regions in their 2.0 5 square field. High-resolution, high sensitivity VLA observations of the SagDIG Hi content have been obtained by Young & Lo (1997) (see also Lo et al. 1993). About 1.2 × 107 M of H+He have been estimated (u ...
Lecture17
... B - V = +2 corresponds to a cool red star The Sun has B - V = 0.62 corresponding to a temperature of 6000 K ...
... B - V = +2 corresponds to a cool red star The Sun has B - V = 0.62 corresponding to a temperature of 6000 K ...
The Sagittarius dwarf irregular galaxy
... Hii regions were investigated by Strobel et al. (1991), who detected 3 regions in their 2.0 5 square field. High-resolution, high sensitivity VLA observations of the SagDIG Hi content have been obtained by Young & Lo (1997) (see also Lo et al. 1993). About 1.2 × 107 M of H+He have been estimated (u ...
... Hii regions were investigated by Strobel et al. (1991), who detected 3 regions in their 2.0 5 square field. High-resolution, high sensitivity VLA observations of the SagDIG Hi content have been obtained by Young & Lo (1997) (see also Lo et al. 1993). About 1.2 × 107 M of H+He have been estimated (u ...
High Energy Phenomena in Supergiant X-ray Binaries - HAL-Insu
... circumstellar medium, by fitting their spectral energy distribution (SED). The main results of this study are that 15 of these IGRs are identified as HMXBs, and among them 12 HMXBs contain massive and luminous early-type companion stars. By combining optical, NIR and MIR photometry, and fitting thei ...
... circumstellar medium, by fitting their spectral energy distribution (SED). The main results of this study are that 15 of these IGRs are identified as HMXBs, and among them 12 HMXBs contain massive and luminous early-type companion stars. By combining optical, NIR and MIR photometry, and fitting thei ...
The 3-D shaping of NGC 6741: a massive, fast
... semi-axes, respectively), surrounded by a sharp low-excitation skin (the ionization front), and embedded into a spherical (radius≃0.080 pc), almost-neutral, high-density (n(H I) ≃7×103 atoms cm−3 ) halo containing a large fraction of the nebular mass (Mhalo ≥0.20 M⊙ ). The kinematics, physical condi ...
... semi-axes, respectively), surrounded by a sharp low-excitation skin (the ionization front), and embedded into a spherical (radius≃0.080 pc), almost-neutral, high-density (n(H I) ≃7×103 atoms cm−3 ) halo containing a large fraction of the nebular mass (Mhalo ≥0.20 M⊙ ). The kinematics, physical condi ...
Data-mining in astrophysics. A search for new variable stars in
... If you change the order of use of different parameters, the end result may be quite different, and some interesting variable stars may be lost. ...
... If you change the order of use of different parameters, the end result may be quite different, and some interesting variable stars may be lost. ...
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.