The evolution of close binaries with white dwarf components
... and thermal equilibrium. The orbit is affected by the re-arrangement (and possible loss) of mass and angular momentum, and it widens in general. When mass transfer becomes unstable, the donor star will overflow its Roche lobe further upon mass loss. Subsequently the mass transfer rate increases even m ...
... and thermal equilibrium. The orbit is affected by the re-arrangement (and possible loss) of mass and angular momentum, and it widens in general. When mass transfer becomes unstable, the donor star will overflow its Roche lobe further upon mass loss. Subsequently the mass transfer rate increases even m ...
A spectroscopic study of detached binary systems using precise radial velocities
... Double-lined solutions were obtained for HD 206804 (K7V+K7V), which previously had two competing astrometric solutions but no spectroscopic solution, and a newly discovered seventhmagnitude system, HD 181958 (F6V+F7V). This latter system has the distinction of having components and orbital character ...
... Double-lined solutions were obtained for HD 206804 (K7V+K7V), which previously had two competing astrometric solutions but no spectroscopic solution, and a newly discovered seventhmagnitude system, HD 181958 (F6V+F7V). This latter system has the distinction of having components and orbital character ...
Small glitches: the role of strange nuggets?
... that if they pass Earth, some seismic signals would be detected (Anderson 2003; Herrin et al. 2006). More detailed ...
... that if they pass Earth, some seismic signals would be detected (Anderson 2003; Herrin et al. 2006). More detailed ...
Models for circumstellar nebulae around red and blue supergiants
... capable of ionizing the H II regions. The hot ionized gas of the H II region, or diffuse nebula, can expand into the cold surrounding neutral gas, decreasing the density of the nebula and increasing the volume of ionized gas. During their lives, stars interact with the surrounding interstellar mediu ...
... capable of ionizing the H II regions. The hot ionized gas of the H II region, or diffuse nebula, can expand into the cold surrounding neutral gas, decreasing the density of the nebula and increasing the volume of ionized gas. During their lives, stars interact with the surrounding interstellar mediu ...
The effect of dark matter capture on binary stars
... This work has led to a number of interesting conclusions: (1) Binary stars, due to their orbital motion, can produce more collisions that result in initially bound orbits. However, the gravitational interaction with two masses quickly scatters nearly all WIMPs out of the system. The few that survive ...
... This work has led to a number of interesting conclusions: (1) Binary stars, due to their orbital motion, can produce more collisions that result in initially bound orbits. However, the gravitational interaction with two masses quickly scatters nearly all WIMPs out of the system. The few that survive ...
Abstract The Star Formation History of Low Surface Brightness Galaxies
... The star formation histories of low surface brightness galaxies are interesting but poorly constrained. These objects tend to be rather blue, contradicting the initial impression that they may simply be faded remnants of higher surface brightness galaxies whose star formation has finished. Other sce ...
... The star formation histories of low surface brightness galaxies are interesting but poorly constrained. These objects tend to be rather blue, contradicting the initial impression that they may simply be faded remnants of higher surface brightness galaxies whose star formation has finished. Other sce ...
The Emission Line Spectrum of Active Galactic
... The broad emission lines observed in AGNs have a FWHM which is typically in the range 5 000-10 000 km s−1 and show different kinds of profiles that usually are not Gaussian or even symmetrical (Stirpe 1991; Corbin 1995). The half-width at zero intensity of Hβ can be extremely large, reaching 35 000 ...
... The broad emission lines observed in AGNs have a FWHM which is typically in the range 5 000-10 000 km s−1 and show different kinds of profiles that usually are not Gaussian or even symmetrical (Stirpe 1991; Corbin 1995). The half-width at zero intensity of Hβ can be extremely large, reaching 35 000 ...
CENTRAL STARS OF PLANETARY NEBULAE IN THE LARGE
... With respect to the study of planetary nebulae ( PNe) systems, those in the Large Magellanic Cloud ( LMC) are important for two primary reasons. Attempts to describe the evolution of Galactic PNe are hindered by large relative uncertainties in their distances, which carry over into physical paramete ...
... With respect to the study of planetary nebulae ( PNe) systems, those in the Large Magellanic Cloud ( LMC) are important for two primary reasons. Attempts to describe the evolution of Galactic PNe are hindered by large relative uncertainties in their distances, which carry over into physical paramete ...
as a PDF - Living Reviews in Solar Physics
... Solar magnetic fields control essentially the entire outer solar atmosphere, they heat coronal gas to millions of degrees, they produce flares whose by-products such as shock waves and high-energy particles travel through interplanetary space to eventually interact with planetary atmospheres; the so ...
... Solar magnetic fields control essentially the entire outer solar atmosphere, they heat coronal gas to millions of degrees, they produce flares whose by-products such as shock waves and high-energy particles travel through interplanetary space to eventually interact with planetary atmospheres; the so ...
Galaxy Disks Further
... disk mass distribution can be obtained from hydrostatic considerations, comparing the thickness and velocity dispersion of the stars, as was pioneered for the Galaxy by Kapteyn (1922) and Oort (1932), or the HI gas (van der Kruit 1981). Sanders & McGaugh (2002) have reviewed modified Newtonian dynam ...
... disk mass distribution can be obtained from hydrostatic considerations, comparing the thickness and velocity dispersion of the stars, as was pioneered for the Galaxy by Kapteyn (1922) and Oort (1932), or the HI gas (van der Kruit 1981). Sanders & McGaugh (2002) have reviewed modified Newtonian dynam ...
THE LUMINOSITY FUNCTION OF X
... Over more than two decades, X-ray surveys have been improving and extending the known AGN luminosity function by including sources at low luminosity, with or without optical emission lines, and hidden by a dense obscuring medium. The Extended Medium Sensitivity Survey (Gioia et al. 1990) was one of ...
... Over more than two decades, X-ray surveys have been improving and extending the known AGN luminosity function by including sources at low luminosity, with or without optical emission lines, and hidden by a dense obscuring medium. The Extended Medium Sensitivity Survey (Gioia et al. 1990) was one of ...
An Optical Study of Young Stellar Clusters
... rapidly, on dynamical time-scales, or is a quasi-static process in which protostellar cores take many free-fall time-scales to contract (e.g., Tan et al., 2006; Elmegreen, 2007). The observational study of young stars in a star forming region is fundamental to improve our understanding of such probl ...
... rapidly, on dynamical time-scales, or is a quasi-static process in which protostellar cores take many free-fall time-scales to contract (e.g., Tan et al., 2006; Elmegreen, 2007). The observational study of young stars in a star forming region is fundamental to improve our understanding of such probl ...
High-mass star-forming cloud G0.38+0.04 in the Galactic center dust
... Sgr B2 (M): there is only one SiO maser spot in Sgr B2, located near Mehringer et al. (1994) H2 CO Source C (not to be confused with Cloud C, the topic of this paper). The Sgr B2 H2 CO maser C is peculiar even among the Sgr B2 masers in that the emission appears to be spatially and spectrally resolv ...
... Sgr B2 (M): there is only one SiO maser spot in Sgr B2, located near Mehringer et al. (1994) H2 CO Source C (not to be confused with Cloud C, the topic of this paper). The Sgr B2 H2 CO maser C is peculiar even among the Sgr B2 masers in that the emission appears to be spatially and spectrally resolv ...
The Relation between Interstellar Turbulence and Star Formation
... Understanding the formation of stars in galaxies is central to much of modern astrophysics. For several decades it has been thought that the star formation process is primarily controlled by the interplay between gravity and magnetostatic support, modulated by neutral-ion drift. Recently, however, b ...
... Understanding the formation of stars in galaxies is central to much of modern astrophysics. For several decades it has been thought that the star formation process is primarily controlled by the interplay between gravity and magnetostatic support, modulated by neutral-ion drift. Recently, however, b ...
$doc.title
... Swift observations each. In addition, to measure the diffuse emission from the region, we used data from an RXTE observation campaign in 1996/1997 that were collected while the source was off. Table 1 lists a log of the observations. The binary orbital phases of the 2005, 2007, and 2011 April observ ...
... Swift observations each. In addition, to measure the diffuse emission from the region, we used data from an RXTE observation campaign in 1996/1997 that were collected while the source was off. Table 1 lists a log of the observations. The binary orbital phases of the 2005, 2007, and 2011 April observ ...
Systematic Study of Mass Loss in the Evolution of Massive Stars
... sub-fields of astrophysics. For example, because of their high luminosity, they are the only stars that can be observed in outer galaxies. They are paramount for the early universe re-ionization [2] and they create HII regions due to their ionizing radiation; the nuclear processes in their interiors ...
... sub-fields of astrophysics. For example, because of their high luminosity, they are the only stars that can be observed in outer galaxies. They are paramount for the early universe re-ionization [2] and they create HII regions due to their ionizing radiation; the nuclear processes in their interiors ...
The evolution of massive stars and their spectra
... observables of massive stars can be strongly influenced by a radiatively driven stellar wind that is characteristic of these stars. The effects of mass loss on the observables depend on the initial mass and metallicity, since they are in general more noticeable in MS stars with large initial masses, ...
... observables of massive stars can be strongly influenced by a radiatively driven stellar wind that is characteristic of these stars. The effects of mass loss on the observables depend on the initial mass and metallicity, since they are in general more noticeable in MS stars with large initial masses, ...
JCMT HARP CO 3-2 Observations of Molecular Outflows in W5
... in Figure 2 to provide an overview of where star formation is most active. The figures in Section 4.2 show outflow locations overlaid on small-scale images. Because our detection method involved searching for high-velocity outflows directly by eye, there should be no false detections. However, it is ...
... in Figure 2 to provide an overview of where star formation is most active. The figures in Section 4.2 show outflow locations overlaid on small-scale images. Because our detection method involved searching for high-velocity outflows directly by eye, there should be no false detections. However, it is ...
Evolution of Stars and Stellar Populations
... those properties that are needed to understand and apply the methods discussed in the rest of the book, that is, the evolution with time of the photometric and chemical properties (i.e. evolution of effective temperatures, luminosities, surface chemical abundances) of stars, as a function of their i ...
... those properties that are needed to understand and apply the methods discussed in the rest of the book, that is, the evolution with time of the photometric and chemical properties (i.e. evolution of effective temperatures, luminosities, surface chemical abundances) of stars, as a function of their i ...
Galactic Winds Sylvain Veilleux
... manifestation of the generation of vast fluxes of energy by processes which are not yet properly understood.’ This comment echoed the discovery of the first quasar in 1962, and the slow realization that many extragalactic radio sources must be enormously energetic, powered by processes that could on ...
... manifestation of the generation of vast fluxes of energy by processes which are not yet properly understood.’ This comment echoed the discovery of the first quasar in 1962, and the slow realization that many extragalactic radio sources must be enormously energetic, powered by processes that could on ...
Cygnus X-1
Cygnus X-1 (abbreviated Cyg X-1) is a well-known galactic X-ray source, thought to be a black hole, in the constellation Cygnus. It was discovered in 1964 during a rocket flight and is one of the strongest X-ray sources seen from Earth, producing a peak X-ray flux density of 6977229999999999999♠2.3×10−23 Wm−2 Hz−1 (7003230000000000000♠2.3×103 Jansky). Cygnus X-1 was the first X-ray source widely accepted to be a black hole and it remains among the most studied astronomical objects in its class. The compact object is now estimated to have a mass about 14.8 times the mass of the Sun and has been shown to be too small to be any known kind of normal star, or other likely object besides a black hole. If so, the radius of its event horizon is about 7004440000000000000♠44 km.Cygnus X-1 belongs to a high-mass X-ray binary system about 7019574266339685654♠6070 ly from the Sun that includes a blue supergiant variable star designated HDE 226868 which it orbits at about 0.2 AU, or 20% of the distance from the Earth to the Sun. A stellar wind from the star provides material for an accretion disk around the X-ray source. Matter in the inner disk is heated to millions of degrees, generating the observed X-rays. A pair of jets, arranged perpendicular to the disk, are carrying part of the energy of the infalling material away into interstellar space.This system may belong to a stellar association called Cygnus OB3, which would mean that Cygnus X-1 is about five million years old and formed from a progenitor star that had more than 7001400000000000000♠40 solar masses. The majority of the star's mass was shed, most likely as a stellar wind. If this star had then exploded as a supernova, the resulting force would most likely have ejected the remnant from the system. Hence the star may have instead collapsed directly into a black hole.Cygnus X-1 was the subject of a friendly scientific wager between physicists Stephen Hawking and Kip Thorne in 1975, with Hawking betting that it was not a black hole. He conceded the bet in 1990 after observational data had strengthened the case that there was indeed a black hole in the system. This hypothesis has not been confirmed due to a lack of direct observation but has generally been accepted from indirect evidence.