Confronting Dark Matter Powered Stars with Recent Results from
... Explaining the nature of the non-luminous matter component, called dark matter (DM), is most crucial to both scienti c elds. This study combines considerations about the nature of the dark matter particle and fundamental questions concerning the nature of the rst stars forming in the history of th ...
... Explaining the nature of the non-luminous matter component, called dark matter (DM), is most crucial to both scienti c elds. This study combines considerations about the nature of the dark matter particle and fundamental questions concerning the nature of the rst stars forming in the history of th ...
A Spectroscopic Survey of a Sample of Active M Dwarfs.
... We note that Fleming (1998) did not publish the full designations; the SIMBAD resolver requires the names as we present them, with the blank between RX and J, and the fourth declination digit. We add A or B to designate double components of visual doubles, where separate spectra were taken. Column 2 ...
... We note that Fleming (1998) did not publish the full designations; the SIMBAD resolver requires the names as we present them, with the blank between RX and J, and the fourth declination digit. We add A or B to designate double components of visual doubles, where separate spectra were taken. Column 2 ...
Chapter 2 Mass Transfer in Binary Systems
... the variation of the radius of a star with deep convective envelope depends on its mass as R M. If mass is lost, the star expands, and cannot maintain within its Roche lobe, leading to very rapid mass transfer and the formation of common envelope. ...
... the variation of the radius of a star with deep convective envelope depends on its mass as R M. If mass is lost, the star expands, and cannot maintain within its Roche lobe, leading to very rapid mass transfer and the formation of common envelope. ...
When we look at a neighboring galaxy (such as M31, the
... The Andromeda Galaxy, also known as M31, is a spiral galaxy physically larger, but less massive, than our Milky Way Galaxy. The Andromeda is the largest member of the Local Group, a cluster of about 30 galaxies that are gravitationally attracted to one another. At a distance of 2.5 million light-yea ...
... The Andromeda Galaxy, also known as M31, is a spiral galaxy physically larger, but less massive, than our Milky Way Galaxy. The Andromeda is the largest member of the Local Group, a cluster of about 30 galaxies that are gravitationally attracted to one another. At a distance of 2.5 million light-yea ...
A Simple Model for r-Process Scatter and Halo Evolution
... effects due to the integral values of Ni . These are particularly noticeable when N̄a < 1, which occurs when NSN < 1/fa ≃ 25, or [Fe/H] . −2.6. In this regime, most points will cluster at Rb , with only a few at higher values. Furthermore, R = R̄Na /NSN is also quantized. The lower envelope of the n ...
... effects due to the integral values of Ni . These are particularly noticeable when N̄a < 1, which occurs when NSN < 1/fa ≃ 25, or [Fe/H] . −2.6. In this regime, most points will cluster at Rb , with only a few at higher values. Furthermore, R = R̄Na /NSN is also quantized. The lower envelope of the n ...
Can stellar wobble in triple systems mimic a planet?
... The first extrasolar planets were detected by the measurement of the wobble of the parent star. This wobble leads to the periodic modulation of three observables: the radial velocity, the position on the sky and the time of arrival of periodic signals. We show that the same wobble, and therefore the ...
... The first extrasolar planets were detected by the measurement of the wobble of the parent star. This wobble leads to the periodic modulation of three observables: the radial velocity, the position on the sky and the time of arrival of periodic signals. We show that the same wobble, and therefore the ...
Study Systematics on the ICM metallicity measurements
... Oxygen and Magnesium At high temperatures, Oxygen and Magnesium are very weak. For both elements, slight changes in the continuum produce large deviation on the lines’ emissivity measurements. ...
... Oxygen and Magnesium At high temperatures, Oxygen and Magnesium are very weak. For both elements, slight changes in the continuum produce large deviation on the lines’ emissivity measurements. ...
The physics of star formation - Yale Astronomy
... Stars are the fundamental units of luminous matter in the universe, and they are responsible, directly or indirectly, for most of what we see when we observe it. They also serve as our primary tracers of the structure and evolution of the universe and its contents. Consequently, it is of central imp ...
... Stars are the fundamental units of luminous matter in the universe, and they are responsible, directly or indirectly, for most of what we see when we observe it. They also serve as our primary tracers of the structure and evolution of the universe and its contents. Consequently, it is of central imp ...
Slides from Lecture19 - Department of Physics & Astronomy
... Determining Size of MW Galaxy • We have not always known that the diameter of our Galaxy is ~ 50 kpc (as illustrated in following slide) • For example, Herschel’s map of our Galaxy (1785) based on star counts … – Thin disk not much more than 1 kpc across – Sun approximately at center of disk ...
... Determining Size of MW Galaxy • We have not always known that the diameter of our Galaxy is ~ 50 kpc (as illustrated in following slide) • For example, Herschel’s map of our Galaxy (1785) based on star counts … – Thin disk not much more than 1 kpc across – Sun approximately at center of disk ...
PoS(AASKA14)174 - Proceeding of science
... facing planetary astronomers is understanding how the small pebbles in the disk surrounding a young star are able to stick together to form the boulders that ultimately coalesce into planets. At both smaller and larger sizes, the growth mechanisms are understood, but this key step in the planet form ...
... facing planetary astronomers is understanding how the small pebbles in the disk surrounding a young star are able to stick together to form the boulders that ultimately coalesce into planets. At both smaller and larger sizes, the growth mechanisms are understood, but this key step in the planet form ...
Core-Halo Age Gradients and Star Formation in the Orion Nebula
... showing a wide age spread in the apparent ages of pre-main sequence (PMS) stars. However, the interpretation of HRD age spreads is quite controversial for both observational and theoretical reasons, as reviewed by Preibisch (2012). For example, Huff & Stahler (2006) construct a model of the Orion Ne ...
... showing a wide age spread in the apparent ages of pre-main sequence (PMS) stars. However, the interpretation of HRD age spreads is quite controversial for both observational and theoretical reasons, as reviewed by Preibisch (2012). For example, Huff & Stahler (2006) construct a model of the Orion Ne ...
Bright 22 μm excess candidates from the wise all-sky
... Since the first discovery of a debris disk around Vega via excess IR, (Aumann et al. 1984), excess IR has been a useful tool in the search for debris disks. To date, many works have been conducted on the search for stars with excess IR emission. Most of the samples used in previous work were selecte ...
... Since the first discovery of a debris disk around Vega via excess IR, (Aumann et al. 1984), excess IR has been a useful tool in the search for debris disks. To date, many works have been conducted on the search for stars with excess IR emission. Most of the samples used in previous work were selecte ...
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.