Massive Star Formation in the Galactic Center
... The three clusters are similar in many respects, as they are all young and contain 104 M in stars. They have very high central stellar mass densities, up to nearly 106 M pc−3 , exceeding central densities in most globular clusters. They have luminosities of 107−8 L , and are responsible for heat ...
... The three clusters are similar in many respects, as they are all young and contain 104 M in stars. They have very high central stellar mass densities, up to nearly 106 M pc−3 , exceeding central densities in most globular clusters. They have luminosities of 107−8 L , and are responsible for heat ...
New brown dwarfs and giant planets
... Davy Kirkpatrick & Pat Lowrance (IPAC), Adam Burgasser (UCLA)) Aim: find all dwarfs later than M4 within 20 parsecs 1. 2MASS/NLTT cross-referencing: (m(r) – K) p 2. Deep van Biesbroeck survey for wide cpm companions 3. 2MASS-direct: (J-K) p ...
... Davy Kirkpatrick & Pat Lowrance (IPAC), Adam Burgasser (UCLA)) Aim: find all dwarfs later than M4 within 20 parsecs 1. 2MASS/NLTT cross-referencing: (m(r) – K) p 2. Deep van Biesbroeck survey for wide cpm companions 3. 2MASS-direct: (J-K) p ...
Using Atmospheric Cherenkov Telescope arrays as Intensity Interferometers S. LeBohec and J. Holder
... Citter-Zernike theorem, γd , the complex degree of coherence is the normalized Fourier transform of the source intensity distribution projected on a line parallel to the line joining the two detectors. Measuring |γd |2 provides information on the angular structure of the source. The shot noise from ...
... Citter-Zernike theorem, γd , the complex degree of coherence is the normalized Fourier transform of the source intensity distribution projected on a line parallel to the line joining the two detectors. Measuring |γd |2 provides information on the angular structure of the source. The shot noise from ...
Gamma-Ray Bursts
... star explodes in a supernova explosion. The core collapses into a neutron star, and the rest of the star explodes in a supernova explosion. The core collapses into a white dwarf, and the rest of the star explodes to form a planetary nebula. The core collapses into a neutron star, and the rest of the ...
... star explodes in a supernova explosion. The core collapses into a neutron star, and the rest of the star explodes in a supernova explosion. The core collapses into a white dwarf, and the rest of the star explodes to form a planetary nebula. The core collapses into a neutron star, and the rest of the ...
Carbon-enhanced metal-poor stars in dwarf galaxies
... 2005; Aoki et al. 2007; Yong et al. 2013; Norris et al. 2013; Lee et al. 2013). These objects are usually defined to have carbon-to-iron ratio [C/Fe]> 0.7 (Aoki et al. 2007), and they can be divided into two main populations: carbon-rich stars that exhibit an excess in heavy elements formed by slow ...
... 2005; Aoki et al. 2007; Yong et al. 2013; Norris et al. 2013; Lee et al. 2013). These objects are usually defined to have carbon-to-iron ratio [C/Fe]> 0.7 (Aoki et al. 2007), and they can be divided into two main populations: carbon-rich stars that exhibit an excess in heavy elements formed by slow ...
Chapter 3 (Lectures 7
... The cause of the Herbig AeBe phenomenon is still not clearly understood. In extreme cases the luminosity of the activity is very large; the emission lines may carry of the order of 10% of the total stellar radiation. It is not clear how dynamo magnetic activity (like that of the Sun), in a star with ...
... The cause of the Herbig AeBe phenomenon is still not clearly understood. In extreme cases the luminosity of the activity is very large; the emission lines may carry of the order of 10% of the total stellar radiation. It is not clear how dynamo magnetic activity (like that of the Sun), in a star with ...
110 - Institute for Astronomy
... gravity does not significantly affect the expansion of H II regions. Such clouds achieve a balance between the decay of turbulent energy and its regeneration in H II regions; summed over clouds, the implied ionizing luminosity and star formation rate are roughly consistent with the Galactic total. H ...
... gravity does not significantly affect the expansion of H II regions. Such clouds achieve a balance between the decay of turbulent energy and its regeneration in H II regions; summed over clouds, the implied ionizing luminosity and star formation rate are roughly consistent with the Galactic total. H ...
205 Advances in Natural and Applied Sciences, 4(2): 205-209, 2010 ISSN 1995-0772
... A binary stellar system is simply one in which two stars orbit around a common center of mass, that is they are gravitationally bound to each other. Almost 50 percent of the stars in the sky are part of a binary or multiple stellar systems. A sub-class of binary systems are X-ray binaries, the syste ...
... A binary stellar system is simply one in which two stars orbit around a common center of mass, that is they are gravitationally bound to each other. Almost 50 percent of the stars in the sky are part of a binary or multiple stellar systems. A sub-class of binary systems are X-ray binaries, the syste ...
Document
... As the Universe expands, the separation between small scale density fluctuations increases. At the same time, the deviation between the density of fluctuations and the mean density of the Universe also increases. In other words, over-dense regions attract more matter at the expense of draining under ...
... As the Universe expands, the separation between small scale density fluctuations increases. At the same time, the deviation between the density of fluctuations and the mean density of the Universe also increases. In other words, over-dense regions attract more matter at the expense of draining under ...
Variability in the CoRoT photometry of three hot O
... The next target is HD 46150, the second hottest star in NGC 2244. Literature values for the spectral type are between O5 V((f)) (Underhill & Gilroy 1990; Maı́z-Apellániz et al. 2004) and O5.5 V((f)) (Conti & Ebbets 1977; Garmany et al. 1980). The detailed study of Mahy et al. (2009) confirms the O5 ...
... The next target is HD 46150, the second hottest star in NGC 2244. Literature values for the spectral type are between O5 V((f)) (Underhill & Gilroy 1990; Maı́z-Apellániz et al. 2004) and O5.5 V((f)) (Conti & Ebbets 1977; Garmany et al. 1980). The detailed study of Mahy et al. (2009) confirms the O5 ...
Introduction: The History and Technique of Stellar Classification
... Introduction: The History and Technique of Stellar Classification Patterns of absorption lines were first observed in the spectrum of the sun by the German physicist Joseph von Fraunhofer early in the 1800’s, but it was not until late in that century that astronomers were able to routinely examine t ...
... Introduction: The History and Technique of Stellar Classification Patterns of absorption lines were first observed in the spectrum of the sun by the German physicist Joseph von Fraunhofer early in the 1800’s, but it was not until late in that century that astronomers were able to routinely examine t ...
Cosmology Notes - U of L Class Index
... A black hole results when the gravitational field around an object becomes so strong that not even light can escape from it—the Schwarzchild radius is the “distance” (indirectly arrived at, since the space-time metric actually changes at the surface, the “event horizon”—which is defined as the surfa ...
... A black hole results when the gravitational field around an object becomes so strong that not even light can escape from it—the Schwarzchild radius is the “distance” (indirectly arrived at, since the space-time metric actually changes at the surface, the “event horizon”—which is defined as the surfa ...
Discovery of Eclipsing Binary with the Longest Known Period
... We report the discovery of the eclipsing binary MASTER OT J095310.04+335352.8 with extreme parameters. The orbital period P=69.1 yr is more than 2.5 times longer than that of Epsilon Aurigae. The light curve is characterized by an extremely deep total eclipse (with a depth of more than 4.5m) of symm ...
... We report the discovery of the eclipsing binary MASTER OT J095310.04+335352.8 with extreme parameters. The orbital period P=69.1 yr is more than 2.5 times longer than that of Epsilon Aurigae. The light curve is characterized by an extremely deep total eclipse (with a depth of more than 4.5m) of symm ...
The connection between stellar activity cycles and magnetic field
... activity have resulted from these types of observations including research into chromospheric and photometric variability (Lockwood et al. 2007) and the use of activity proxies as age indicators (Mamajek & Hillenbrand 2008; Pace 2013). Some authors have also studied possible trends involving the act ...
... activity have resulted from these types of observations including research into chromospheric and photometric variability (Lockwood et al. 2007) and the use of activity proxies as age indicators (Mamajek & Hillenbrand 2008; Pace 2013). Some authors have also studied possible trends involving the act ...
- ANU Repository
... planets around Kepler M dwarfs represent a distinctive population that can be compared with those around solar-type stars to test models of planet formation (e.g. Gaidos & Mann 2014). There have been several recent works estimating the occurrence of planets around M dwarfs, the distribution with rad ...
... planets around Kepler M dwarfs represent a distinctive population that can be compared with those around solar-type stars to test models of planet formation (e.g. Gaidos & Mann 2014). There have been several recent works estimating the occurrence of planets around M dwarfs, the distribution with rad ...
Population synthesis for symbiotic stars with white dwarf accretors
... rithm for angular momentum loss during the commonenvelope stages of evolution; Winters and his collaborators (Winters et al. 2000, 2002, 2003) studied the hydrodynamical structure of the stellar wind around AGB stars with low mass-loss rate and low wind outflow velocity. New observational catalogue a ...
... rithm for angular momentum loss during the commonenvelope stages of evolution; Winters and his collaborators (Winters et al. 2000, 2002, 2003) studied the hydrodynamical structure of the stellar wind around AGB stars with low mass-loss rate and low wind outflow velocity. New observational catalogue a ...
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.