A re-examination of galactic conformity and a comparison with semi
... of the effect and how it changes as a function of the mass of the central galaxy. Conformity extends over a central galaxy stellar mass range spanning two orders of magnitude. The scale dependence and the precise nature of the effect depend on the mass of the central. In central galaxies with masses ...
... of the effect and how it changes as a function of the mass of the central galaxy. Conformity extends over a central galaxy stellar mass range spanning two orders of magnitude. The scale dependence and the precise nature of the effect depend on the mass of the central. In central galaxies with masses ...
ROSAT Isolated Neutron Stars
... Basics Compact objects are born in the core collapse following a type II supernova explosion Present rate of SN events in the Galaxy: ≈ 0.01/yr (possibly higher in the past) Galactic population of compact objects: ≈ 108 – 109 (≈ 1% of stars) ...
... Basics Compact objects are born in the core collapse following a type II supernova explosion Present rate of SN events in the Galaxy: ≈ 0.01/yr (possibly higher in the past) Galactic population of compact objects: ≈ 108 – 109 (≈ 1% of stars) ...
Talk
... Applications of pulsar timing • Neutron stars with companions • Known companions: white dwarfs, neutron stars, planets • Need to incorporate general relativity to model orbits of WD and NS binary systems • Tests of general relativity ...
... Applications of pulsar timing • Neutron stars with companions • Known companions: white dwarfs, neutron stars, planets • Need to incorporate general relativity to model orbits of WD and NS binary systems • Tests of general relativity ...
The age of elliptical galaxies and bulges in a merger model The age
... a galaxy, these observations suggest that many present-day ellipticals have undergone a merger-induced starburst in the past. Likewise, analyses of the stellar ages of elliptical galaxies using absorption-line index strengths show that the outer parts of elliptical galaxies are both older and more m ...
... a galaxy, these observations suggest that many present-day ellipticals have undergone a merger-induced starburst in the past. Likewise, analyses of the stellar ages of elliptical galaxies using absorption-line index strengths show that the outer parts of elliptical galaxies are both older and more m ...
Properties of simulated Milky Way-mass galaxies in loose group and
... early type galaxies; i.e. the so-called morphology-density relation (Dressler et al. 1997). While the accretion of field galaxies into denser environments may strip gas from the galaxy and leave a slowly reddening S0 galaxy, it will do little else to alter the morphology. Morphological transformatio ...
... early type galaxies; i.e. the so-called morphology-density relation (Dressler et al. 1997). While the accretion of field galaxies into denser environments may strip gas from the galaxy and leave a slowly reddening S0 galaxy, it will do little else to alter the morphology. Morphological transformatio ...
Nuclear forces and their impact on neutron-rich
... includes configurations from the large basis space via different many-body methods. Great advances to access large basis spaces have been made with coupled-cluster (CC) theory (24). The CC method starts from a closed-shell reference state and includes correlations through a similarity transformation ...
... includes configurations from the large basis space via different many-body methods. Great advances to access large basis spaces have been made with coupled-cluster (CC) theory (24). The CC method starts from a closed-shell reference state and includes correlations through a similarity transformation ...
An extended main-sequence turn-off in the Small
... corresponds to a sequence of single hydrogen-burning stars – is provided by the pair of values ((m − M)0 , AV ) = (18.9, 0.25). The rightmost sequence of stars along the MS is easily explained as being a sequence of binaries (both apparent and real). Indeed, the expected position of equal-mass detac ...
... corresponds to a sequence of single hydrogen-burning stars – is provided by the pair of values ((m − M)0 , AV ) = (18.9, 0.25). The rightmost sequence of stars along the MS is easily explained as being a sequence of binaries (both apparent and real). Indeed, the expected position of equal-mass detac ...
Research Report for 2015/2016
... and a team of scientists and students from Rice and Lowell Observatory continued a search for radial velocity perturbations that might be caused by planets around young stars. Sensitive searches for older planets have turned up many such objects, but finding them around young stars is difficult beca ...
... and a team of scientists and students from Rice and Lowell Observatory continued a search for radial velocity perturbations that might be caused by planets around young stars. Sensitive searches for older planets have turned up many such objects, but finding them around young stars is difficult beca ...
Models of the Structure and Evolution of Protoplanetary Disks
... Dusty circumstellar disks have been the focus of intense observational interest in recent years, largely because they are thought to be the birthplaces of planetary systems. These observational efforts have yielded many new insights on the structure and evolution of these disks. In spite of major de ...
... Dusty circumstellar disks have been the focus of intense observational interest in recent years, largely because they are thought to be the birthplaces of planetary systems. These observational efforts have yielded many new insights on the structure and evolution of these disks. In spite of major de ...
... addition, high-precision photometric data obtained with MOST satellite showed the presence of multiple periods in the Be stars ζ-Oph (Walker et al. 2005b) and HD 163 868 (Walker et al. 2005a). They modelled the detected frequencies as nrp in terms of p-modes in the case of ζ-Oph, and g- and r-modes ...
The CCD Photometric Calibration Cookbook
... This cookbook is aimed firmly at people who are new to astronomical photometry, especially those who either have a set of photometric observations to reduce (perhaps observed by a colleague) or who are planning a programme of photometric observations, perhaps for the first time. Typical readers migh ...
... This cookbook is aimed firmly at people who are new to astronomical photometry, especially those who either have a set of photometric observations to reduce (perhaps observed by a colleague) or who are planning a programme of photometric observations, perhaps for the first time. Typical readers migh ...
Improving Galactic Center Astrometry by Reducing the Effects of
... 2007; Kraniotis 2007; Nucita et al. 2007; Will 2008). Such gains will also probe the possibility that the supermassive black hole is moving with respect to the central stellar cluster, due either to the gravitational influence of a massive companion or from a systematic effect produced by improper a ...
... 2007; Kraniotis 2007; Nucita et al. 2007; Will 2008). Such gains will also probe the possibility that the supermassive black hole is moving with respect to the central stellar cluster, due either to the gravitational influence of a massive companion or from a systematic effect produced by improper a ...
Characterizing filaments in regions of high-mass star
... turbulent flows, and then prestellar cores arise from gravitational fragmentation of the densest filaments. Whether this scenario also applies to regions of high-mass star formation is an open question, in part because the resolution of Herschel is insufficient to resolve the inner width of filament ...
... turbulent flows, and then prestellar cores arise from gravitational fragmentation of the densest filaments. Whether this scenario also applies to regions of high-mass star formation is an open question, in part because the resolution of Herschel is insufficient to resolve the inner width of filament ...
Fundamental properties of Ana González Galán
... will slowly collapse and heat up. Nuclear reactions in a shell of gas outside the core will provide a new source of energy, and cause the star to expand outward in the "red giant" phase. The most important factor that influences the life of a star on the MS is its own mass. More massive stars have h ...
... will slowly collapse and heat up. Nuclear reactions in a shell of gas outside the core will provide a new source of energy, and cause the star to expand outward in the "red giant" phase. The most important factor that influences the life of a star on the MS is its own mass. More massive stars have h ...
Libra - www.BahaiStudies.net
... Iota Librae is a complex multiple star, 377 light-years from Earth, with both optical and true binary components. The Visible at latitudes between +65° and −90°. primary appears as a blue-white star of magnitude 4.5; it is a Best visible at 21:00 (9 p.m.) during the month of June. binary star indivi ...
... Iota Librae is a complex multiple star, 377 light-years from Earth, with both optical and true binary components. The Visible at latitudes between +65° and −90°. primary appears as a blue-white star of magnitude 4.5; it is a Best visible at 21:00 (9 p.m.) during the month of June. binary star indivi ...
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.