The MGC - St Andrews Astronomy Group
... The Hubble Tuning Fork Breakdown • Numerous new galaxy types have been found which do not fit on the original Hubble tuning fork diagram ...
... The Hubble Tuning Fork Breakdown • Numerous new galaxy types have been found which do not fit on the original Hubble tuning fork diagram ...
The evolution of dwarf galaxy satellites with different dark matter
... Therefore, in order to make progress beyond the idealized simulation we devise a numerical strategy that in the past has only been attempted for simulations of galaxies in clusters ( Dubinski (1999); Mastropietro et al. (2005)). In this approach, known as the ”replacement technique”, cosmological su ...
... Therefore, in order to make progress beyond the idealized simulation we devise a numerical strategy that in the past has only been attempted for simulations of galaxies in clusters ( Dubinski (1999); Mastropietro et al. (2005)). In this approach, known as the ”replacement technique”, cosmological su ...
Two New Triple Star Systems with Detectable Inner Orbital Motions
... We considered whether the combined and overlaid movement sequences (the three proven components) are visible and predictable. For the inner pair CHR4 Aa,Ab measurements exist from 1984 to 1994. These cover an arc of about 60 degrees and show a well-defined orbital arc. After 1994, the inner system u ...
... We considered whether the combined and overlaid movement sequences (the three proven components) are visible and predictable. For the inner pair CHR4 Aa,Ab measurements exist from 1984 to 1994. These cover an arc of about 60 degrees and show a well-defined orbital arc. After 1994, the inner system u ...
U P C NIVERSITAT
... 2011fe and 2014J, no normal stellar progenitor has ever been directly identified. Overall, the challenging, unsolved stellar progenitor problem for SNe Ia stands in marked contrast to the case of core-collapse supernovae, whose stellar progenitors are highly-luminous, massive stars. Observational ev ...
... 2011fe and 2014J, no normal stellar progenitor has ever been directly identified. Overall, the challenging, unsolved stellar progenitor problem for SNe Ia stands in marked contrast to the case of core-collapse supernovae, whose stellar progenitors are highly-luminous, massive stars. Observational ev ...
STEREO observations of long period variables
... became the first member of the variability class called long period variables (LPVs) today. Being easily detectable because of the large photometric amplitudes, they were intensively studied thereafter and represent now a prominent group within the General Catalogue of Variable Stars (GCVS; Samus et ...
... became the first member of the variability class called long period variables (LPVs) today. Being easily detectable because of the large photometric amplitudes, they were intensively studied thereafter and represent now a prominent group within the General Catalogue of Variable Stars (GCVS; Samus et ...
Time Dependence of the Charge Transfer Efficiency on the WFPC2
... WFPC2 observations in the outskirts of the globular cluster Omega Cen were used to make the measurements. The F814W filter was employed since it provides the highest S/N determination of CTE (since the stars tend to be red and the background is lower than at F555W, resulting in larger values of CTE ...
... WFPC2 observations in the outskirts of the globular cluster Omega Cen were used to make the measurements. The F814W filter was employed since it provides the highest S/N determination of CTE (since the stars tend to be red and the background is lower than at F555W, resulting in larger values of CTE ...
shell properties
... Although IRC+10216 is faint at optical wavelengths, we recently reported deep imaging in B and V with the CanadaFrance-Hawaii Telescope (CFHT) that provides an extended view of the envelope at arc second resolution (Mauron & Huggins 1999, hereafter Paper I). At these short wavelengths, the envelope ...
... Although IRC+10216 is faint at optical wavelengths, we recently reported deep imaging in B and V with the CanadaFrance-Hawaii Telescope (CFHT) that provides an extended view of the envelope at arc second resolution (Mauron & Huggins 1999, hereafter Paper I). At these short wavelengths, the envelope ...
Str\" omgren uvby photometry of the peculiar globular cluster NGC
... & Kirby 2012; Mucciarelli et al. 2012). A spread in [Ca/H] is also supported by the results of Lee et al. (2013), who showed that NGC 2419’s bright RGB stars show a spread, and a hint of a bimodality, in the hk photometric index (constructed from Strömgren Ca, b, and y magnitudes, the first of which ...
... & Kirby 2012; Mucciarelli et al. 2012). A spread in [Ca/H] is also supported by the results of Lee et al. (2013), who showed that NGC 2419’s bright RGB stars show a spread, and a hint of a bimodality, in the hk photometric index (constructed from Strömgren Ca, b, and y magnitudes, the first of which ...
University of Groningen Photo-ionization studies of nebulae
... The transition phase between the Asymptotic Giant Branch (AGB) and planetary nebulae (PNe) has gained much attention over the last decade. AGB stars lose mass fast and get obscured by their circumstellar dust. As the star leaves the AGB, its mass loss rate decreases significantly and the star may be ...
... The transition phase between the Asymptotic Giant Branch (AGB) and planetary nebulae (PNe) has gained much attention over the last decade. AGB stars lose mass fast and get obscured by their circumstellar dust. As the star leaves the AGB, its mass loss rate decreases significantly and the star may be ...
Foretellings of Ragnar\" ok: World-engulfing Asymptotic Giants and
... stellar radius are also the drivers of the mass loss through the generation of shocks in the stellar envelope that allow the nucleation of dust grains (see, e.g., Bowen 1988, and references therein). As grains nucleate and grow they experience the force exerted by the stellar radiation pressure and ...
... stellar radius are also the drivers of the mass loss through the generation of shocks in the stellar envelope that allow the nucleation of dust grains (see, e.g., Bowen 1988, and references therein). As grains nucleate and grow they experience the force exerted by the stellar radiation pressure and ...
Notable long-period eclipsing binaries. Part I. - Project VS
... Detached eclipsing binaries can provide fundamental physical properties of the components through the analysis of light and radial velocity curves. This allows to determine masses, radii and luminosities of individual stars and provides test bases for stellar structure and evolution models, and inte ...
... Detached eclipsing binaries can provide fundamental physical properties of the components through the analysis of light and radial velocity curves. This allows to determine masses, radii and luminosities of individual stars and provides test bases for stellar structure and evolution models, and inte ...
Towards the understanding of the deepest layers of solar
... With the recent launch of the Kepler satellite, thousands of stars are being monitored to provide high-quality seismic data. These seismic data combined with non-seismic surface stellar observables can provide valuable information about the global properties of pulsating stars, such as their mass, r ...
... With the recent launch of the Kepler satellite, thousands of stars are being monitored to provide high-quality seismic data. These seismic data combined with non-seismic surface stellar observables can provide valuable information about the global properties of pulsating stars, such as their mass, r ...
The Milky Way as a galaxy
... Historically the distance determination to the Hyades, using the moving cluster parallax, was extremely important because it defined the scale to all other, larger distances. Its constituent stars of known distance are used to construct a calibrated Hertzsprung–Russell diagram which forms the basis ...
... Historically the distance determination to the Hyades, using the moving cluster parallax, was extremely important because it defined the scale to all other, larger distances. Its constituent stars of known distance are used to construct a calibrated Hertzsprung–Russell diagram which forms the basis ...
Star Tracker Stellar Compass
... only radiation resistance glass, including fiber optic faceplate material, was included in the optical path. Use of the radiation resistant material reduces transmission in the shorter wavelength regions of the CCD response, virtually blocking all light below 500 nm, however, for doses on the order ...
... only radiation resistance glass, including fiber optic faceplate material, was included in the optical path. Use of the radiation resistant material reduces transmission in the shorter wavelength regions of the CCD response, virtually blocking all light below 500 nm, however, for doses on the order ...
Neutron Stars – Cooling and Transport
... The first works on neutron star cooling and thermal emission (Stabler 1960; Tsuruta 1964; Chiu and Salpeter 1964; Morton 1964; Bahcall and Wolf 1965a,b) appeared at the epoch of the discoveries of X-ray sources outside the Solar System in the rocket and balloon experiments (Giacconi et al. 1962; Bow ...
... The first works on neutron star cooling and thermal emission (Stabler 1960; Tsuruta 1964; Chiu and Salpeter 1964; Morton 1964; Bahcall and Wolf 1965a,b) appeared at the epoch of the discoveries of X-ray sources outside the Solar System in the rocket and balloon experiments (Giacconi et al. 1962; Bow ...
Computer Simulation of Dark Matter Effects on Galaxy Collisions
... tails on either end of the galaxy. In figure 9, after several collisions, the tail extends out farther into space. This feature matches colliding galaxies viewed from observatories, this image below shows that this is a realistic feature. ...
... tails on either end of the galaxy. In figure 9, after several collisions, the tail extends out farther into space. This feature matches colliding galaxies viewed from observatories, this image below shows that this is a realistic feature. ...
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.