First detection of helium emissions in RR Lyrae⋆
... Just after the first apparition of the Hα emission shoulder (at ϕ = 0.887), a sudden onset of the He I λ5875.66 (D3) emission appears at ϕ = 0.902. It is weakly blueshifted (−6 km s−1 ), while the Hα emission component is more blueshifted (−43 km s−1 ). Figures 3 and 4 present the variation in the H ...
... Just after the first apparition of the Hα emission shoulder (at ϕ = 0.887), a sudden onset of the He I λ5875.66 (D3) emission appears at ϕ = 0.902. It is weakly blueshifted (−6 km s−1 ), while the Hα emission component is more blueshifted (−43 km s−1 ). Figures 3 and 4 present the variation in the H ...
The Layout of the Night Sky - Peterborough Astronomical Society
... its orbit around the Sun, the celestial equator and ecliptic would be the same circle. Because of Earth’s tilt, the Sun appears highest in the sky relative to the celestial equator when the Earth is at one position in its orbit. This happens on or about June 21, and we call this the summer solstice ...
... its orbit around the Sun, the celestial equator and ecliptic would be the same circle. Because of Earth’s tilt, the Sun appears highest in the sky relative to the celestial equator when the Earth is at one position in its orbit. This happens on or about June 21, and we call this the summer solstice ...
ON THE ORIGIN OF THE SALPETER SLOPE FOR THE INITIAL
... limiting masses that are on the order of the largest clump masses, this should cause an analogous steepening of the cluster mass function under these circumstances. As described above, the ICMF generally has a slope β = 2, but it would be interesting to evaluate any trends. We also note that our mod ...
... limiting masses that are on the order of the largest clump masses, this should cause an analogous steepening of the cluster mass function under these circumstances. As described above, the ICMF generally has a slope β = 2, but it would be interesting to evaluate any trends. We also note that our mod ...
properties and evolution of disks around pre-main
... Several teams of authors found that all the SEDs of HAeBe stars can instead be interpreted as the emission of spherical envelopes of various optical depths and density profiles (Berrilli et al. 1992; Miroshnichenko et al. 1997; Pezzuto et al. 1997). Far-infrared, high-spatial-resolution observations ...
... Several teams of authors found that all the SEDs of HAeBe stars can instead be interpreted as the emission of spherical envelopes of various optical depths and density profiles (Berrilli et al. 1992; Miroshnichenko et al. 1997; Pezzuto et al. 1997). Far-infrared, high-spatial-resolution observations ...
Merger of binary neutron stars with realistic equations of state in full
... sound speed of nuclear matter (e.g., [12]). This implies that the pressure and the internal energy associated with the finite thermal energy (temperature) are not still as large as those of the cold part. From this reason, we adopt a hybrid equation of state in which the finite-temperature part gene ...
... sound speed of nuclear matter (e.g., [12]). This implies that the pressure and the internal energy associated with the finite thermal energy (temperature) are not still as large as those of the cold part. From this reason, we adopt a hybrid equation of state in which the finite-temperature part gene ...
Chemical Composition of Selected Metal Poor Stars
... evolutionary state: Main Sequence (core hydrogen burning), Subgiant (shell hydrogen burning), Giant (phase after the exhaustion of hydrogen burning, where expansion provides gravitational stability, till the state of He-flash), Horizontal Branch (core helium burning and shell hydrogen burning), Asym ...
... evolutionary state: Main Sequence (core hydrogen burning), Subgiant (shell hydrogen burning), Giant (phase after the exhaustion of hydrogen burning, where expansion provides gravitational stability, till the state of He-flash), Horizontal Branch (core helium burning and shell hydrogen burning), Asym ...
Testing
... • Dying stars expel gas and new elements, producing hot bubbles (~106 K). • Hot gas cools, allowing atomic hydrogen clouds to form (~100–10,000 K). • Further cooling permits molecules to form, making molecular clouds (~30 K). • Gravity forms new stars (and planets) in molecular clouds. ...
... • Dying stars expel gas and new elements, producing hot bubbles (~106 K). • Hot gas cools, allowing atomic hydrogen clouds to form (~100–10,000 K). • Further cooling permits molecules to form, making molecular clouds (~30 K). • Gravity forms new stars (and planets) in molecular clouds. ...
driving galaxy evolution since z=1
... decreases steadily with time. • In addition to this, star formation is shut off in group galaxies, accelerating their evolution. ...
... decreases steadily with time. • In addition to this, star formation is shut off in group galaxies, accelerating their evolution. ...
Hot Horizontal Branch Stars in the Galactic Bulge. I
... that has left the giant branch to become a core-helium-burning star on the horizontal branch (HB) depends primarily on its age and metallicity. At lower metallicities, a wide range in color is both found and predicted among BHB stars if modest mass loss is assumed. Among populations of solar metalli ...
... that has left the giant branch to become a core-helium-burning star on the horizontal branch (HB) depends primarily on its age and metallicity. At lower metallicities, a wide range in color is both found and predicted among BHB stars if modest mass loss is assumed. Among populations of solar metalli ...
QAT Trial Answers 2015
... BCS theory proposes that the electrons in superconductors at temperatures below their critical temperatures form pairs in special electron-lattice-electron interactions to form what is known as ‘Cooper-pairs’. There is experimental evidence that supports this proposition. The theory also proposes th ...
... BCS theory proposes that the electrons in superconductors at temperatures below their critical temperatures form pairs in special electron-lattice-electron interactions to form what is known as ‘Cooper-pairs’. There is experimental evidence that supports this proposition. The theory also proposes th ...
Astronomy Astrophysics Circumstellar emission in Be/X-ray binaries of the Magellanic
... Aims. We study the optical and near-infrared colour excesses produced by circumstellar emission in a sample of Be/X-ray binaries. Our main goals are exploring whether previously published relations, valid for isolated Be stars, are applicable to Be/X-ray binaries and computing the distance to these ...
... Aims. We study the optical and near-infrared colour excesses produced by circumstellar emission in a sample of Be/X-ray binaries. Our main goals are exploring whether previously published relations, valid for isolated Be stars, are applicable to Be/X-ray binaries and computing the distance to these ...
The cosmological significance of high
... 1999), placing a firm lower limit of 21 kpc on the distance between the HVC and the Sun if the cloud lies just beyond the edge of the disk. At distances of more than 100 kpc, Complex H would be the fourth most massive object in the Local Group, which seems unlikely since no counterpart at other wave ...
... 1999), placing a firm lower limit of 21 kpc on the distance between the HVC and the Sun if the cloud lies just beyond the edge of the disk. At distances of more than 100 kpc, Complex H would be the fourth most massive object in the Local Group, which seems unlikely since no counterpart at other wave ...
Program and Abstract Book - European Southern Observatory
... Mike Dunham (SUNY Fredonia, NY, USA) Stars form from the gravitational collapse of dense molecular cloud cores. In the protostellar phase, mass both accretes from the core onto a protostar, likely through an accretion disk, and is ejected in the form of jets and outflows. It is during this protostel ...
... Mike Dunham (SUNY Fredonia, NY, USA) Stars form from the gravitational collapse of dense molecular cloud cores. In the protostellar phase, mass both accretes from the core onto a protostar, likely through an accretion disk, and is ejected in the form of jets and outflows. It is during this protostel ...
WORD - Astrophysics
... essential questions remain for which the collecting area and angular resolution of an extremely large optical/infrared telescope will prove decisive. Many of these questions deal with the earliest and the latest stages of stellar evolution, plagued by significant unknowns. Determining the entire ste ...
... essential questions remain for which the collecting area and angular resolution of an extremely large optical/infrared telescope will prove decisive. Many of these questions deal with the earliest and the latest stages of stellar evolution, plagued by significant unknowns. Determining the entire ste ...
Oxygen and Neon Abundances of B-Type Stars in Comparison with
... Above all, the discrepancy of oxygen is important, which is (as one of the so-called ˛-elements) considered to be synthesized and distributed essentially by massive stars via type II supernovae. Unlike C and N, which are known to suffer changes due to evolution-induced dredge-up of CN-cycled process ...
... Above all, the discrepancy of oxygen is important, which is (as one of the so-called ˛-elements) considered to be synthesized and distributed essentially by massive stars via type II supernovae. Unlike C and N, which are known to suffer changes due to evolution-induced dredge-up of CN-cycled process ...
pg. 271 - Cornell University
... optical spectra, to derive the electron temperature of the ionized gas for several ions. A correlation between the electron temperature and the ionization potential is found. Ionic abundances for the observed infrared ions have been derived, and the total neon and sulfur abundances have been determi ...
... optical spectra, to derive the electron temperature of the ionized gas for several ions. A correlation between the electron temperature and the ionization potential is found. Ionic abundances for the observed infrared ions have been derived, and the total neon and sulfur abundances have been determi ...
Astronomy Astrophysics Detailed abundances of a large sample of giant stars in... and in the Sagittarius nucleus
... for 76 red giant stars in NGC 6715 (M 54), a massive globular cluster (GC) lying in the nucleus of the Sagittarius dwarf galaxy. We also derived detailed abundances for 27 red giants belonging to the Sgr nucleus. Our abundances measure the intrinsic metallicity dispersion (∼0.19 dex, rms scatter) of ...
... for 76 red giant stars in NGC 6715 (M 54), a massive globular cluster (GC) lying in the nucleus of the Sagittarius dwarf galaxy. We also derived detailed abundances for 27 red giants belonging to the Sgr nucleus. Our abundances measure the intrinsic metallicity dispersion (∼0.19 dex, rms scatter) of ...
Ch 33) Astrophysics and Cosmology
... “nebulae” (Latin for “clouds”). A few of these, such as those in the constellations Andromeda and Orion, can actually be discerned with the naked eye on a clear night. Some are star clusters (Fig. 33–3), groups of stars that are so numerous they appear to be a cloud. Others are glowing clouds of gas ...
... “nebulae” (Latin for “clouds”). A few of these, such as those in the constellations Andromeda and Orion, can actually be discerned with the naked eye on a clear night. Some are star clusters (Fig. 33–3), groups of stars that are so numerous they appear to be a cloud. Others are glowing clouds of gas ...
Effects of color superconductivity on the nucleation of quark matter in
... in the value of Nc is expected to be within one or two orders of magnitude. In any case, all the qualitative features of our scenario will be not affected by the uncertainty in the value of Nc . In order to explore the astrophysical implications of the nucleation, we introduce the concept of critical ...
... in the value of Nc is expected to be within one or two orders of magnitude. In any case, all the qualitative features of our scenario will be not affected by the uncertainty in the value of Nc . In order to explore the astrophysical implications of the nucleation, we introduce the concept of critical ...
Pre-main sequence stars, emission stars and recent star formation in
... Myr), there is a chance for a spread in the age of the stars, depending on the duration of star formation. An estimation of this formation time-scale in the clusters formed in a star forming complex, will indicate the duration of star formation and its direction of propagation within the complex. In ...
... Myr), there is a chance for a spread in the age of the stars, depending on the duration of star formation. An estimation of this formation time-scale in the clusters formed in a star forming complex, will indicate the duration of star formation and its direction of propagation within the complex. In ...
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.