Star Formation in the Rosette Complex
... The pioneering observations by Gosachinskii & Khersonskii (1982) of the HI emission at 21 cm made with the RATAN-600 telescope revealed that the Rosette Complex and the Monoceros Loop were enclosed in a thin HI envelope 130 pc in diameter, possibly expanding at 20 km·s−1 , suggesting that the supern ...
... The pioneering observations by Gosachinskii & Khersonskii (1982) of the HI emission at 21 cm made with the RATAN-600 telescope revealed that the Rosette Complex and the Monoceros Loop were enclosed in a thin HI envelope 130 pc in diameter, possibly expanding at 20 km·s−1 , suggesting that the supern ...
Recent star formation in local, morphologically disturbed
... Survey (SDSS; optical, see Adelman-McCarthy et al. 2006) properties of early-type galaxies on the optical red sequence, originally studied by van Dokkum (2005, hereafter vD05). The novelty of the vD05 study was the unprecedented depth of the optical imaging employed to study the red galaxy populatio ...
... Survey (SDSS; optical, see Adelman-McCarthy et al. 2006) properties of early-type galaxies on the optical red sequence, originally studied by van Dokkum (2005, hereafter vD05). The novelty of the vD05 study was the unprecedented depth of the optical imaging employed to study the red galaxy populatio ...
talk at lensing and dark matter conference Ohio state 2004
... • Main conclusion: Macho’s as main component of Dark Matter are ruled out • But found significant extra microlensing ...
... • Main conclusion: Macho’s as main component of Dark Matter are ruled out • But found significant extra microlensing ...
Testing the Initial-Final Mass Relationship of White Dwarfs Silvia Catal´ an Ruiz
... total age or metallicity, are available. Most of the works carried out up to now have focused in studying white dwarfs in open clusters (Ferrario et al. 2005, Dobbie et al. 2006), whose ages can be determined from model fits to the turn-off location in a color-magnitude diagram. One of the aims of t ...
... total age or metallicity, are available. Most of the works carried out up to now have focused in studying white dwarfs in open clusters (Ferrario et al. 2005, Dobbie et al. 2006), whose ages can be determined from model fits to the turn-off location in a color-magnitude diagram. One of the aims of t ...
Properties of rapidly rotating PNS with antikaon condensates at
... as a millisecond, or a frequency that is greater than 500 Hz. The fastest known pulsar, PSR J1748-2446ad, that has been observed to date was discovered [13] in 2004. It has a rotation period of 1.397 ms and frequency of 716 Hz. PNS may rotate with higher frequency than this or the NS may gain rotati ...
... as a millisecond, or a frequency that is greater than 500 Hz. The fastest known pulsar, PSR J1748-2446ad, that has been observed to date was discovered [13] in 2004. It has a rotation period of 1.397 ms and frequency of 716 Hz. PNS may rotate with higher frequency than this or the NS may gain rotati ...
Binary evolution using the theory of osculating orbits
... classical scheme, owing to the gravitational force applied onto the stars by the mass transfer stream. Additionally, during the rapid phase of mass exchange, the donor star is spun down on a timescale shorter than the tidal synchronization timescale, leading to sub-synchronous rotation. Consequently ...
... classical scheme, owing to the gravitational force applied onto the stars by the mass transfer stream. Additionally, during the rapid phase of mass exchange, the donor star is spun down on a timescale shorter than the tidal synchronization timescale, leading to sub-synchronous rotation. Consequently ...
Astronomy Astrophysics Kuiper belts around nearby stars &
... and submillimetre emission compared to that expected from stellar photospheres, suggests that leftover planetesimal belts analogous to the asteroid- and comet reservoirs of the solar system are common. Aims. Sensitive submillimetre observations are essential to detect and characterise cold extended ...
... and submillimetre emission compared to that expected from stellar photospheres, suggests that leftover planetesimal belts analogous to the asteroid- and comet reservoirs of the solar system are common. Aims. Sensitive submillimetre observations are essential to detect and characterise cold extended ...
Observed Properties of Exoplanets
... Gas giants accrete most of the gas within their tidal reach filling the Hill sphere around them with the heated, gaseous envelope. Further gas accretion is slowed both by the diminishing amounts of remaining local gas and by the extended envelope, leading to predicted growth times of 5–10 Myr. This g ...
... Gas giants accrete most of the gas within their tidal reach filling the Hill sphere around them with the heated, gaseous envelope. Further gas accretion is slowed both by the diminishing amounts of remaining local gas and by the extended envelope, leading to predicted growth times of 5–10 Myr. This g ...
2 The Concept of “Spectral Classes”
... Representation of spectral types and luminosity classes Pairs of digits for TT, tt, and LL may range from 00 through 99. These 100 numbers are cells denoting spectral types, subtypes, and luminosity classes respectively, as in the Morgan-Keenan (MK) system, - and beyond. For all four major classific ...
... Representation of spectral types and luminosity classes Pairs of digits for TT, tt, and LL may range from 00 through 99. These 100 numbers are cells denoting spectral types, subtypes, and luminosity classes respectively, as in the Morgan-Keenan (MK) system, - and beyond. For all four major classific ...
The Current Status of Galaxy Formation
... the luminous dwarfs accrete gas at later epochs. Most gas is ejected by the first generations of SNe for < 50 km/s, leaving dim stellar remnants behind. systems with escape velocity ∼ In very low-mass halos gas cannot even fall in, because its specific entropy is too high (Rees, 1986). This entropy ...
... the luminous dwarfs accrete gas at later epochs. Most gas is ejected by the first generations of SNe for < 50 km/s, leaving dim stellar remnants behind. systems with escape velocity ∼ In very low-mass halos gas cannot even fall in, because its specific entropy is too high (Rees, 1986). This entropy ...
Applications of Photospheric Spot Temperature Models ... Stellar Angular Momentum Evolution
... conservation of angular momentum tells us that highly condensed clouds should be rotating faster than clouds that have just begun their gravitational collapse. Furthermore, we would also expect that not all the material from the natal cloud will immediately end up at the center of mass of the cloud ...
... conservation of angular momentum tells us that highly condensed clouds should be rotating faster than clouds that have just begun their gravitational collapse. Furthermore, we would also expect that not all the material from the natal cloud will immediately end up at the center of mass of the cloud ...
Chemical Evolution of Galactic Systems
... is whether pollution from intermediate-mass stellar winds is responsible for anomalous abundances in globular cluster stars. We test this scenario by modelling the formation and chemical evolution of a globular cluster. Recently, the most detailed abundance pattern ever measured beyond the local uni ...
... is whether pollution from intermediate-mass stellar winds is responsible for anomalous abundances in globular cluster stars. We test this scenario by modelling the formation and chemical evolution of a globular cluster. Recently, the most detailed abundance pattern ever measured beyond the local uni ...
STELLAR SPECTRA A. Basic Line Formation
... star. The early-type stars display the hydrogen Balmer lines prominently, but these become weak in solar-type spectra in which the Ca+ H and K resonance lines are strongest. The M dwarfs on the bottom display strong molecular bands. From Novotny (1973). ...
... star. The early-type stars display the hydrogen Balmer lines prominently, but these become weak in solar-type spectra in which the Ca+ H and K resonance lines are strongest. The M dwarfs on the bottom display strong molecular bands. From Novotny (1973). ...
Catalogs of Hot White Dwarfs in the Milky Way from GALEX`s
... in galaxies. Most of the stellar mass is shed in the AGB and PN phases, but the evolution through these phases is still subject to considerable uncertainties, in particular regarding mass loss and the efficiency of the third dredge-up. Stars within an intial mass range of ∼0.8 to 8M⊙ end as WDs with ...
... in galaxies. Most of the stellar mass is shed in the AGB and PN phases, but the evolution through these phases is still subject to considerable uncertainties, in particular regarding mass loss and the efficiency of the third dredge-up. Stars within an intial mass range of ∼0.8 to 8M⊙ end as WDs with ...
Cosmological Implications of Trace
... to have been previous discussion of scenarios in which trace-charge imbalances play a key role in resisting gravitational attraction (Weyl [1917], Majumder [1947], Bonnor [1980]), but its cosmological implications – with the important exception of gravitational red-shifts (Bonnor and Wickramasuriya ...
... to have been previous discussion of scenarios in which trace-charge imbalances play a key role in resisting gravitational attraction (Weyl [1917], Majumder [1947], Bonnor [1980]), but its cosmological implications – with the important exception of gravitational red-shifts (Bonnor and Wickramasuriya ...
galaxy formation with cold gas accretion and evolving stellar initial
... and assumed star formation history, among which the stellar IMF contributes the dominant systematic error between different data sets. It is simple to correct the stellar mass between the often used Salpeter, Kroupa (2001), and C03 IMFs, which are assumed to be independent of galaxy mass and redshif ...
... and assumed star formation history, among which the stellar IMF contributes the dominant systematic error between different data sets. It is simple to correct the stellar mass between the often used Salpeter, Kroupa (2001), and C03 IMFs, which are assumed to be independent of galaxy mass and redshif ...
Dark-matter halo mergers as a fertile environment for low
... H− formation is boosted in the shocked regions, while the H2 fraction is regulated both via H− as well as the underlying density field. The increase of the H− fraction is a consequence of its temperaturedependent formation rate (see reaction 7 in Table 1). Although no strong differences are observed ...
... H− formation is boosted in the shocked regions, while the H2 fraction is regulated both via H− as well as the underlying density field. The increase of the H− fraction is a consequence of its temperaturedependent formation rate (see reaction 7 in Table 1). Although no strong differences are observed ...
ppt - chris.engelbrecht.nithep.ac.za
... • Individual knots rich in ejecta • Spectrum of central bar and outer ring show ISM-like abundances - relic structure from equatoriallyenhanced stellar wind? • Oxygen and Neon abundances seen in ejecta are enhanced above levels expected; very little iron observed - reverse shock appears to still be ...
... • Individual knots rich in ejecta • Spectrum of central bar and outer ring show ISM-like abundances - relic structure from equatoriallyenhanced stellar wind? • Oxygen and Neon abundances seen in ejecta are enhanced above levels expected; very little iron observed - reverse shock appears to still be ...
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.