on the absolute age of the metal-rich globular m71
... Leaman et al. (2013, hereafter LVM13) found that for abundances [Fe/H] ⩾ 1.8 dex, the GCs obey two different AMRs. In particular, they found that one-third of the entire sample is, at a fixed cluster age, systematically more metal-rich by 0.6 dex. Moreover, they suggest that the bulk of the metalrich ...
... Leaman et al. (2013, hereafter LVM13) found that for abundances [Fe/H] ⩾ 1.8 dex, the GCs obey two different AMRs. In particular, they found that one-third of the entire sample is, at a fixed cluster age, systematically more metal-rich by 0.6 dex. Moreover, they suggest that the bulk of the metalrich ...
planetary construction zones in occultation: discovery of an
... not be face on – more likely the disk would have a nonzero inclination respect to the planet-star orbital plane, so the star need not be completely geometrically eclipsed by such a circumplanetary disk. The rings of Saturn have 5 The author dereddened the UBV photometry for OGLE-LMCECL-17782 from Ma ...
... not be face on – more likely the disk would have a nonzero inclination respect to the planet-star orbital plane, so the star need not be completely geometrically eclipsed by such a circumplanetary disk. The rings of Saturn have 5 The author dereddened the UBV photometry for OGLE-LMCECL-17782 from Ma ...
Silicon isotopic abundance toward evolved stars and its application
... Most of the presolar grains have 29 Si/30 Si ratios around 1.5, but evidence of lower 29 Si/30 Si ratios are also found in presolar SiC grains, for instance, types X2 and Z in Fig. 3. The type Z grains may have originated from a nearby evolved star (see also Zinner et al. 2006). Additionally, the ty ...
... Most of the presolar grains have 29 Si/30 Si ratios around 1.5, but evidence of lower 29 Si/30 Si ratios are also found in presolar SiC grains, for instance, types X2 and Z in Fig. 3. The type Z grains may have originated from a nearby evolved star (see also Zinner et al. 2006). Additionally, the ty ...
Red Supergiants and Extinction Law in the Large Magelanic Cloud
... the large surface granulation presented in these stars affects broad-band colors and that, due primarily to metallicity, there is a shift in average RSG spectral type: the LMC M-type supergiants scales being cooler than the Galactic scale by 50 K. When compared to distributions of nearby OB stars th ...
... the large surface granulation presented in these stars affects broad-band colors and that, due primarily to metallicity, there is a shift in average RSG spectral type: the LMC M-type supergiants scales being cooler than the Galactic scale by 50 K. When compared to distributions of nearby OB stars th ...
The mass of the Milky Way: Limits from a newly assembled set of
... and halo objects. Our sample consists of 11 satellite galaxies, 137 globular clusters, and 413 field horizontal-branch (FHB) stars up to distances of 10 kpc from the Sun. Roughly half of the objects in this sample have measured proper motions, permitting the use of their full space motions in our an ...
... and halo objects. Our sample consists of 11 satellite galaxies, 137 globular clusters, and 413 field horizontal-branch (FHB) stars up to distances of 10 kpc from the Sun. Roughly half of the objects in this sample have measured proper motions, permitting the use of their full space motions in our an ...
Chapter 4 The Formation of Population III stars in a ΛCDM universe
... of the volume of the halo are relatively hot (∼ 1000 Kelvin), due primarily to accretion shocks formed by gas raining onto the filaments and into the halo. However, as we zoom in towards the center of the halo we can see that the high-density gas is at a much lower temperature (a few hundred Kelvin) ...
... of the volume of the halo are relatively hot (∼ 1000 Kelvin), due primarily to accretion shocks formed by gas raining onto the filaments and into the halo. However, as we zoom in towards the center of the halo we can see that the high-density gas is at a much lower temperature (a few hundred Kelvin) ...
Infrared Properties of Star-Forming Dwarf Galaxies. I. Dwarf Irregular
... the NIR light of dIs can be considered to be predominantly contributed by stars older than about 4 Gyr. Although exponential at large radii, surface brightness profiles for the unresolved component flatten in the centers. They can be fitted across the whole range of radii with a hyperbolic secant (s ...
... the NIR light of dIs can be considered to be predominantly contributed by stars older than about 4 Gyr. Although exponential at large radii, surface brightness profiles for the unresolved component flatten in the centers. They can be fitted across the whole range of radii with a hyperbolic secant (s ...
T Tauri stars Optical lucky imaging polarimetry of HL and XZ Tau
... causing a break in the hydrostatic balance. The breaking causes a second collapse which continues until all the H2 is exhausted and a subsequent hydrostatic core is formed — a protostar. Protostar The heavily embedded object, a protostar, represents the earliest stages of star formation, the dense c ...
... causing a break in the hydrostatic balance. The breaking causes a second collapse which continues until all the H2 is exhausted and a subsequent hydrostatic core is formed — a protostar. Protostar The heavily embedded object, a protostar, represents the earliest stages of star formation, the dense c ...
Parity violating measurements of neutron densities
... Demorest et al: PSR J1614-2230 has 1.97+/- 0.04 Msun. Delay in pulse arrival ...
... Demorest et al: PSR J1614-2230 has 1.97+/- 0.04 Msun. Delay in pulse arrival ...
THE INTERIORS OF GIANT PLANETS
... Solar System. The discovery of giant planets orbiting other stars is a formidable opportunity to learn more about these objects, what their composition is, how various processes influence their structure and evolution, and most importantly how they form. Jupiter, Saturn, Uranus, and Neptune can be s ...
... Solar System. The discovery of giant planets orbiting other stars is a formidable opportunity to learn more about these objects, what their composition is, how various processes influence their structure and evolution, and most importantly how they form. Jupiter, Saturn, Uranus, and Neptune can be s ...
The Binary Populations of Eight Globular Clusters in the Outer Halo
... We exploit three indexes provided by the adopted software and described in detail by Anderson et al. (2008) as diagnostics of photometric quality: the fraction of flux in the stellar aperture from its neighbours (o), the fractional residuals in the fit of the PSF to the pixel (q), and the rms of the ...
... We exploit three indexes provided by the adopted software and described in detail by Anderson et al. (2008) as diagnostics of photometric quality: the fraction of flux in the stellar aperture from its neighbours (o), the fractional residuals in the fit of the PSF to the pixel (q), and the rms of the ...
spatially resolved star formation history of milky way satellites
... galaxies and their own satellites form a self-gravitating association called the Local Group, and hence, the satellite galaxies that reside in it are called local dwarf galaxies. Local dwarf galaxies are crutial for understanding several key aspects of modern astrophysics (Mateo, 1998; Tolstoy et al ...
... galaxies and their own satellites form a self-gravitating association called the Local Group, and hence, the satellite galaxies that reside in it are called local dwarf galaxies. Local dwarf galaxies are crutial for understanding several key aspects of modern astrophysics (Mateo, 1998; Tolstoy et al ...
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, ...
Unsolved Mystery of Molecules Found in
... radiation levels are thousands of times stronger than in the Milky Way. In fact, says Cordiner, DIB carriers seem comfortable almost everywhere except in the clouds of dense gas where stars are born. "The carriers are readily formed but not readily destroyed in a wide range of different environments ...
... radiation levels are thousands of times stronger than in the Milky Way. In fact, says Cordiner, DIB carriers seem comfortable almost everywhere except in the clouds of dense gas where stars are born. "The carriers are readily formed but not readily destroyed in a wide range of different environments ...
Chandra Characterization of X-ray Emission in the Young F
... 113766A+B spectrum, extracted over both sources with an r=20 pixel circular aperture. The combined spectrum is shown in Figure 3a, and is rather soft. We estimate a total HD 113766 A+B system luminosity of Lx = 2.2 x 1029 erg s-1. We also extracted separate spectra for the “West” and “East” sources, ...
... 113766A+B spectrum, extracted over both sources with an r=20 pixel circular aperture. The combined spectrum is shown in Figure 3a, and is rather soft. We estimate a total HD 113766 A+B system luminosity of Lx = 2.2 x 1029 erg s-1. We also extracted separate spectra for the “West” and “East” sources, ...
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.