On the nature of sn stars. I. A detailed abundance study
... related to CP stars. Initially Abt & Levato proposed a shell-like nature to explain the sn stars, although this scenario was subsequently questioned. There is no general agreement about their origin. We aim to derive abundances for a sample of 9 stars, including sn and non-sn stars, to determine the ...
... related to CP stars. Initially Abt & Levato proposed a shell-like nature to explain the sn stars, although this scenario was subsequently questioned. There is no general agreement about their origin. We aim to derive abundances for a sample of 9 stars, including sn and non-sn stars, to determine the ...
Stargazing For Beginners: A Binocular Tour of the Southern Night Sky
... equivalent of US$100-$200, and it’s often possible to find a used pair for much less. Binoculars are ideal for beginning stargazers because they are intuitive to use and show a wide area of sky at one time. And they bring into view hundreds of deep-sky objects and thousands of stars that cannot be s ...
... equivalent of US$100-$200, and it’s often possible to find a used pair for much less. Binoculars are ideal for beginning stargazers because they are intuitive to use and show a wide area of sky at one time. And they bring into view hundreds of deep-sky objects and thousands of stars that cannot be s ...
83-98
... The observed parameters that are used in birthsite determinations are the distances, the space velocity components, and ages. Amongst these, the distances are known to an accuracy of ± 10 per cent. As a typical example if we consider ζ Gem, then a random error of 10 per cent in the distance correspo ...
... The observed parameters that are used in birthsite determinations are the distances, the space velocity components, and ages. Amongst these, the distances are known to an accuracy of ± 10 per cent. As a typical example if we consider ζ Gem, then a random error of 10 per cent in the distance correspo ...
X. Nuclear star clusters in low-mass early-type galaxies
... computations, the theoretical framework for the dissipational formation of NSCs provides less quantitative predictions than the inspiralling cluster scenario. There is evidence that both the in situ as well as the GC inspiralling formation happen in galaxies. Evidence for the GC inspiral scenario is ...
... computations, the theoretical framework for the dissipational formation of NSCs provides less quantitative predictions than the inspiralling cluster scenario. There is evidence that both the in situ as well as the GC inspiralling formation happen in galaxies. Evidence for the GC inspiral scenario is ...
lecture course
... In most galaxy samples there are roughly equal numbers of elliptical, spiral, and peculiar (irregular) galaxies. Elliptical galaxies come in two types - giant ellipticals, which have high brightnesses at their centres and absolute B magnitudes between about -25 and -15, and dwarf ellipticals, which ...
... In most galaxy samples there are roughly equal numbers of elliptical, spiral, and peculiar (irregular) galaxies. Elliptical galaxies come in two types - giant ellipticals, which have high brightnesses at their centres and absolute B magnitudes between about -25 and -15, and dwarf ellipticals, which ...
The physics of star formation
... clouds of ionized gas. The most luminous stars have lifetimes shorter than 10 million years, or 10−3 times the age of the universe, so they must have formed very recently from the dense interstellar gas that is also concentrated in the spiral arms. Star formation occurs also near the centers of some ...
... clouds of ionized gas. The most luminous stars have lifetimes shorter than 10 million years, or 10−3 times the age of the universe, so they must have formed very recently from the dense interstellar gas that is also concentrated in the spiral arms. Star formation occurs also near the centers of some ...
The Most Luminous Protostars in Molecular Clouds: A Hint to
... regions. Actually, the two methods (LTE and virial) yield consistent values mostly within a factor of < 2 for GMCs in the outer arm (Mead, Kutner 1988). We therefore conclude that the cloud masses which we gathered from the literature should be consistent within a small factor. However, errors in th ...
... regions. Actually, the two methods (LTE and virial) yield consistent values mostly within a factor of < 2 for GMCs in the outer arm (Mead, Kutner 1988). We therefore conclude that the cloud masses which we gathered from the literature should be consistent within a small factor. However, errors in th ...
The physics of star formation
... recent decades that we have begun to gain some physical understanding of how this happens. Observations at many wavelengths, especially radio and infrared, have led to great advances in our knowledge of the subject, and the observational study of star formation is now a large and active field of res ...
... recent decades that we have begun to gain some physical understanding of how this happens. Observations at many wavelengths, especially radio and infrared, have led to great advances in our knowledge of the subject, and the observational study of star formation is now a large and active field of res ...
The physics of star formation - Yale Astronomy
... recent decades that we have begun to gain some physical understanding of how this happens. Observations at many wavelengths, especially radio and infrared, have led to great advances in our knowledge of the subject, and the observational study of star formation is now a large and active field of res ...
... recent decades that we have begun to gain some physical understanding of how this happens. Observations at many wavelengths, especially radio and infrared, have led to great advances in our knowledge of the subject, and the observational study of star formation is now a large and active field of res ...
STELLAR AGE VERSUS MASS OF EARLY
... performed visually by allowing age steps of 0.05 dex. The age range was then kept fixed for the other colors (middle and bottom panel). We see from the top panel of Fig. 2 that the SSP of HPL07 exceeds the observed color range at intermediate ages. This is no surprise, though: since the reddest colo ...
... performed visually by allowing age steps of 0.05 dex. The age range was then kept fixed for the other colors (middle and bottom panel). We see from the top panel of Fig. 2 that the SSP of HPL07 exceeds the observed color range at intermediate ages. This is no surprise, though: since the reddest colo ...
Galactic Stellar and Substellar Initial Mass Function Invited Review Gilles Chabrier
... ABSTRACT. We review recent determinations of the present-day mass function (PDMF) and initial mass function (IMF) in various components of the Galaxy—disk, spheroid, young, and globular clusters—and in conditions characteristic of early star formation. As a general feature, the IMF is found to depen ...
... ABSTRACT. We review recent determinations of the present-day mass function (PDMF) and initial mass function (IMF) in various components of the Galaxy—disk, spheroid, young, and globular clusters—and in conditions characteristic of early star formation. As a general feature, the IMF is found to depen ...
FIRST STELLAR ABUNDANCES IN THE DWARF IRREGULAR
... Averages of the abundances of the three stars are marked with hi. All abundances are given with two uncertainties: first the line-to-line scatter, second in italics the estimate of the systematic error due to uncertainties in the stellar atmospheric parameters. ...
... Averages of the abundances of the three stars are marked with hi. All abundances are given with two uncertainties: first the line-to-line scatter, second in italics the estimate of the systematic error due to uncertainties in the stellar atmospheric parameters. ...
sections 19-22 instructor notes
... establish likely distances to Galactic objects from their radial velocities, i.e. using the equations of Galactic motion. ...
... establish likely distances to Galactic objects from their radial velocities, i.e. using the equations of Galactic motion. ...
sections 19-22 instructor notes
... establish likely distances to Galactic objects from their radial velocities, i.e. using the equations of Galactic motion. ...
... establish likely distances to Galactic objects from their radial velocities, i.e. using the equations of Galactic motion. ...
X-Ray Properties of Young Stars and Stellar Clusters
... Star and planet formation is generally viewed as a hydrodynamic process involving gravitational collapse of interstellar material at low temperatures, 10–100 K in molecular cloud cores and 100–1500 K in protoplanetary disks. If thermodynamical equilibrium holds, this material should be neutral excep ...
... Star and planet formation is generally viewed as a hydrodynamic process involving gravitational collapse of interstellar material at low temperatures, 10–100 K in molecular cloud cores and 100–1500 K in protoplanetary disks. If thermodynamical equilibrium holds, this material should be neutral excep ...
– 1 – 1. Emission Lines in Nearby Galaxies 1.1.
... curve (the extinction as a function of wavelength) depends on the mean metallicity of the galaxy. Complex scenarios arise. For example, in a starburst there are so many SN that they bubbles they each blow in the ISM merge together and remain relatively clear of gas. However, in normal star-forming g ...
... curve (the extinction as a function of wavelength) depends on the mean metallicity of the galaxy. Complex scenarios arise. For example, in a starburst there are so many SN that they bubbles they each blow in the ISM merge together and remain relatively clear of gas. However, in normal star-forming g ...
IXO as an observatory in the large telescopes era
... alternative SMBH formation and growth scenarios are possible. For example, they may form via direct, monolithic collapse of hot, dense gas clumps (Bromm & Loeb 2003; Begelman et al. 2006) or via “quasistars” (Begelman et al. 2008). It must also be borne in mind that luminous, optical QSOs, hosting a ...
... alternative SMBH formation and growth scenarios are possible. For example, they may form via direct, monolithic collapse of hot, dense gas clumps (Bromm & Loeb 2003; Begelman et al. 2006) or via “quasistars” (Begelman et al. 2008). It must also be borne in mind that luminous, optical QSOs, hosting a ...
Astronomy 250 - University of Victoria
... Every measured quantity will always have an associated uncertainy. Errors can occur, for example, because of the limitations of the measuring device, because of systematic offsets (see below), because of legitimate dispersions in the data, etc. Example: Suppose you are trying to measure the brightne ...
... Every measured quantity will always have an associated uncertainy. Errors can occur, for example, because of the limitations of the measuring device, because of systematic offsets (see below), because of legitimate dispersions in the data, etc. Example: Suppose you are trying to measure the brightne ...
Spectral Matching for Elemental Abundances of Evolved Stars of Globular Clusters
... In order to understand the origin of globular clusters, large samples of their stars need to be observed and analyzed for their chemical composition. This is especially true for the complex, multimetallic cluster ω Centauri, with its large range of iron, carbon, nitrogen, oxygen, sodium and barium a ...
... In order to understand the origin of globular clusters, large samples of their stars need to be observed and analyzed for their chemical composition. This is especially true for the complex, multimetallic cluster ω Centauri, with its large range of iron, carbon, nitrogen, oxygen, sodium and barium a ...
Hot subdwarf stars-galactic orbits and distribution perpendicular to
... Milky Way using these stars. A relation between these two goals can be found in the connection between the age of subdwarf stars and their spatial distribution. Old stars will more likely be distributed in a thicker disk, due to the heating up of their average kinematics through interactions with ot ...
... Milky Way using these stars. A relation between these two goals can be found in the connection between the age of subdwarf stars and their spatial distribution. Old stars will more likely be distributed in a thicker disk, due to the heating up of their average kinematics through interactions with ot ...
The science case for - Astrophysics
... Were stars the first objects to form? Were the first stars the source of the ultraviolet photons which re-ionised the Universe some 200million years after the Big Bang, and made it transparent? These objects may be visible through their supernovae, or their ionisation zones. How many types of matter ...
... Were stars the first objects to form? Were the first stars the source of the ultraviolet photons which re-ionised the Universe some 200million years after the Big Bang, and made it transparent? These objects may be visible through their supernovae, or their ionisation zones. How many types of matter ...
The Evolution of Star Formation Activity in . Cory R. Wagner
... In this thesis, we explore 7.5 billion years of evolution in cluster galaxy star formation activity using a sample of 11 high-redshift (1 < z < 1.5) clusters from the IRAC Shallow Cluster Survey, and 25 low-redshift (0.15 < z < 1) clusters from The Cluster Lensing And Supernova survey with Hubble. W ...
... In this thesis, we explore 7.5 billion years of evolution in cluster galaxy star formation activity using a sample of 11 high-redshift (1 < z < 1.5) clusters from the IRAC Shallow Cluster Survey, and 25 low-redshift (0.15 < z < 1) clusters from The Cluster Lensing And Supernova survey with Hubble. W ...
solon irving bailey - National Academy of Sciences
... thus describes the arrival at the summit: "Panting for breath, stopping to rest at every three or four steps, often struggling on hands and knees, we kept on, hardly believing there could come an end, when, suddenly, we were there. There was no introduction ; we did not come to the crater; the crate ...
... thus describes the arrival at the summit: "Panting for breath, stopping to rest at every three or four steps, often struggling on hands and knees, we kept on, hardly believing there could come an end, when, suddenly, we were there. There was no introduction ; we did not come to the crater; the crate ...
GALAXIES 626
... Structurally invisible may see them in velocity space (disk moving groups) and integral space (as for halo) and in ...
... Structurally invisible may see them in velocity space (disk moving groups) and integral space (as for halo) and in ...
The Ages of Stars
... arrive at an understanding of a process. Some examples include: • The formation and evolution of proto-planetary disks appear to occur in the first ∼ 100 Myr of a star’s life, with debris disks forming later. At present we can just barely limit this time-scale with the methods available, but clearly ...
... arrive at an understanding of a process. Some examples include: • The formation and evolution of proto-planetary disks appear to occur in the first ∼ 100 Myr of a star’s life, with debris disks forming later. At present we can just barely limit this time-scale with the methods available, but clearly ...
Open cluster
An open cluster, also known as galactic cluster, is a group of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way Galaxy, and many more are thought to exist. They are loosely bound by mutual gravitational attraction and become disrupted by close encounters with other clusters and clouds of gas as they orbit the galactic center, resulting in a migration to the main body of the galaxy as well as a loss of cluster members through internal close encounters. Open clusters generally survive for a few hundred million years, with the most massive ones surviving for a few billion years. In contrast, the more massive globular clusters of stars exert a stronger gravitational attraction on their members, and can survive for longer. Open clusters have been found only in spiral and irregular galaxies, in which active star formation is occurring.Young open clusters may still be contained within the molecular cloud from which they formed, illuminating it to create an H II region. Over time, radiation pressure from the cluster will disperse the molecular cloud. Typically, about 10% of the mass of a gas cloud will coalesce into stars before radiation pressure drives the rest of the gas away.Open clusters are key objects in the study of stellar evolution. Because the cluster members are of similar age and chemical composition, their properties (such as distance, age, metallicity and extinction) are more easily determined than they are for isolated stars. A number of open clusters, such as the Pleiades, Hyades or the Alpha Persei Cluster are visible with the naked eye. Some others, such as the Double Cluster, are barely perceptible without instruments, while many more can be seen using binoculars or telescopes. The Wild Duck Cluster, M11, is an example.