Accretion of brown dwarfs
... 11 objects with large amplitudes, partly irregular variability `T Tauri lightcurves` - produced by accretion in hot spots ...
... 11 objects with large amplitudes, partly irregular variability `T Tauri lightcurves` - produced by accretion in hot spots ...
What powers luminous infrared galaxies?
... To demonstrate this we plot in Fig. 2 LBol /LLyc as a function of the CO-derived average extinction. We have added the luminous galaxies NGC 7469 and UGC 5101 which we have observed in the near-infrared with high resolution imaging spectroscopy (Genzel et al. 1995, 1996). The open triangles show the ...
... To demonstrate this we plot in Fig. 2 LBol /LLyc as a function of the CO-derived average extinction. We have added the luminous galaxies NGC 7469 and UGC 5101 which we have observed in the near-infrared with high resolution imaging spectroscopy (Genzel et al. 1995, 1996). The open triangles show the ...
Computer Animation of Accretion of Neutron Stars
... To correct this situation, we have initialized the velocities of the particles of the red giant to be due to the translational motion of the centre of mass of the red giant, plus the rotational motion with respect to the centre of mass of the red giant too. The angular velocity of the rotational mot ...
... To correct this situation, we have initialized the velocities of the particles of the red giant to be due to the translational motion of the centre of mass of the red giant, plus the rotational motion with respect to the centre of mass of the red giant too. The angular velocity of the rotational mot ...
GRAVITATIONAL SETTLING OF 22Ne AND WHITE DWARF
... of post–asymptotic giant branch stars of low and intermediate masses that reach the hot white dwarf stage with hydrogen-rich surface layers. The basic inner structure expected in a typical white dwarf consists of a degenerate core mostly composed of a mixture of carbon and oxygen (the ashes of core ...
... of post–asymptotic giant branch stars of low and intermediate masses that reach the hot white dwarf stage with hydrogen-rich surface layers. The basic inner structure expected in a typical white dwarf consists of a degenerate core mostly composed of a mixture of carbon and oxygen (the ashes of core ...
Young Galaxies Grow - Astronomical Society of the Pacific
... matter. Their brightest component is a flat, dense disk, where most of their stars are formed along spiral arms. Our Milky Way is a spiral galaxy, • Such disk galaxies assembled mostly in earlier epochs, but they continue to form stars today from remaining gas within the spiral arms. They are also ...
... matter. Their brightest component is a flat, dense disk, where most of their stars are formed along spiral arms. Our Milky Way is a spiral galaxy, • Such disk galaxies assembled mostly in earlier epochs, but they continue to form stars today from remaining gas within the spiral arms. They are also ...
The eccentricities of the barium stars
... have an index of either ,1, 1 or 2. The sample of spectroscopically normal giant binaries have MK spectral classifications indicating giant luminosity and G or K spectral type as the barium stars. The average eccentricities are 0.17 for the barium stars and 0.23 for the normal giants, while a Kolmog ...
... have an index of either ,1, 1 or 2. The sample of spectroscopically normal giant binaries have MK spectral classifications indicating giant luminosity and G or K spectral type as the barium stars. The average eccentricities are 0.17 for the barium stars and 0.23 for the normal giants, while a Kolmog ...
Notes on Photoionized Regions 1. Introduction 2. Hydrogen Nebulae
... and so are not available to ionize hydrogen. However, when the ionized helium recombines, it radiates helium spectral lines and two-‐photon continuum radiation, some of which emerges at hν>13.6 eV. T ...
... and so are not available to ionize hydrogen. However, when the ionized helium recombines, it radiates helium spectral lines and two-‐photon continuum radiation, some of which emerges at hν>13.6 eV. T ...
Galaxies
... spectrum of the star, they found something completely unexpected: the spectrum was flat with several unexpected, and totally unexplainable, emission lines. The object remained a mystery until similar but brighter object, 3C 273, was discovered in 1963. Astronomers noticed that 3C 273 had a normal sp ...
... spectrum of the star, they found something completely unexpected: the spectrum was flat with several unexpected, and totally unexplainable, emission lines. The object remained a mystery until similar but brighter object, 3C 273, was discovered in 1963. Astronomers noticed that 3C 273 had a normal sp ...
Estimating the total radiative power output from the hot outer layers
... data of active regions, coronal holes, sunspots, `quiescent' regions and ares were also used. Based on the derived total power output from all of these di erent plasma, it is shown that a linear relationship involving a single transition region line can be used to provide an accurate estimate of th ...
... data of active regions, coronal holes, sunspots, `quiescent' regions and ares were also used. Based on the derived total power output from all of these di erent plasma, it is shown that a linear relationship involving a single transition region line can be used to provide an accurate estimate of th ...
The effects of red supergiant mass loss on
... mantle to facilitate energy transport (which through a large portion of the mantle happens via convection) from the stellar interior where it is produced out to the photosphere. For a cool star to radiate away the energy at the same high rate at which it is produced by nuclear burning, the radiating ...
... mantle to facilitate energy transport (which through a large portion of the mantle happens via convection) from the stellar interior where it is produced out to the photosphere. For a cool star to radiate away the energy at the same high rate at which it is produced by nuclear burning, the radiating ...
Binocular Sky Newsletter
... easy in a 50mm binocular. These can be used as a good demonstration of averted vision: if you have them both I the same field of view, you may see that the core of M81 becomes more apparent if you look at M82. If you have good skies in the early evening, try M51 (The Whirlpool) and M101 which, altho ...
... easy in a 50mm binocular. These can be used as a good demonstration of averted vision: if you have them both I the same field of view, you may see that the core of M81 becomes more apparent if you look at M82. If you have good skies in the early evening, try M51 (The Whirlpool) and M101 which, altho ...
The extended structure of the dwarf irregular galaxy Sagittarius⋆⋆⋆
... Our photometric data were acquired during different nights between May 28 and July 18, 2012, using the recently refurbished VIMOS, a multi-object spectrograph and wide-field imager mounted on the Nasmyth focus B of the ESO Very Large Telescope (VLT) UT3 (Melipal). The camera is composed of four iden ...
... Our photometric data were acquired during different nights between May 28 and July 18, 2012, using the recently refurbished VIMOS, a multi-object spectrograph and wide-field imager mounted on the Nasmyth focus B of the ESO Very Large Telescope (VLT) UT3 (Melipal). The camera is composed of four iden ...
Globular and Open Clusters in our Galaxy
... Due to their old age, globular clusters typically contain a large number of white dwarfs and also many variable stars, in particular RR Lyrae variables –evolved stars always older than one billion years, found to have roughly the same absolute magnitude (M V = 0.6) and hence allowing to directly det ...
... Due to their old age, globular clusters typically contain a large number of white dwarfs and also many variable stars, in particular RR Lyrae variables –evolved stars always older than one billion years, found to have roughly the same absolute magnitude (M V = 0.6) and hence allowing to directly det ...
Constraining the Bulk Properties of Dense Matter by Measuring
... of binary pulsars is the subject of a separate white paper.) In some sources, most notably the double pulsar, additional constraints come from observations of the companion star. The most precise mass limits come from double neutron star (DNS) systems, like the Hulse-Taylor binary, PSR B1913+16. The ...
... of binary pulsars is the subject of a separate white paper.) In some sources, most notably the double pulsar, additional constraints come from observations of the companion star. The most precise mass limits come from double neutron star (DNS) systems, like the Hulse-Taylor binary, PSR B1913+16. The ...
observation reports
... I checked up on several variables, and R Cygni was now equal to the 9.9 field star in brightness. Chi Cygni had now sunk to 8.3, and was becoming difficult to find in the rich field. A new one for me was R Draconis, which this time was near maximum at 7.3. After a pleasant ramble through Milky Way o ...
... I checked up on several variables, and R Cygni was now equal to the 9.9 field star in brightness. Chi Cygni had now sunk to 8.3, and was becoming difficult to find in the rich field. A new one for me was R Draconis, which this time was near maximum at 7.3. After a pleasant ramble through Milky Way o ...
The Components of a Spiral Galaxy
... molecule has no dipole moment and hence does not emit a spectral line at radio frequencies. But it is detectable in the 21 cm (λ=1420.405751 MHz) hyperfine line a transition between two energy levels due to the magnetic interaction between the quantized electron and proton spins. When the relative s ...
... molecule has no dipole moment and hence does not emit a spectral line at radio frequencies. But it is detectable in the 21 cm (λ=1420.405751 MHz) hyperfine line a transition between two energy levels due to the magnetic interaction between the quantized electron and proton spins. When the relative s ...
The fourth catalogue of Population I Wolf
... classified C (carbon-type), N (nitrogen-type) or W+O (binaries); the more accurate spectral types previously assigned to 15 of them by Feast et al. (1960) being however given. The article included a study of the LMC W − R star surface distribution as well as a discussion of some fundamental physical ...
... classified C (carbon-type), N (nitrogen-type) or W+O (binaries); the more accurate spectral types previously assigned to 15 of them by Feast et al. (1960) being however given. The article included a study of the LMC W − R star surface distribution as well as a discussion of some fundamental physical ...
Planets and Debris Disks: Results from a Spitzer/MIPS Search for IR
... Kuiper Belt objects - debris left over from the process of planet formation. This debris fills the solar system with dust produced by collisions between these small bodies and, in the case of comets, by sublimation of their surface ices. Though solar radiation removes the dust on timescales much sho ...
... Kuiper Belt objects - debris left over from the process of planet formation. This debris fills the solar system with dust produced by collisions between these small bodies and, in the case of comets, by sublimation of their surface ices. Though solar radiation removes the dust on timescales much sho ...
Tracing the evolution of NGC 6397 through the chemical
... early times in the Galaxy. In particular the abundance patterns of elements with atomic number z ≤ 13 may shed light on the properties of stars that early on enriched parts of the star-forming gas with the rest-products of hydrogen-burning at high temperatures. Aims. We analyse and discuss the chemi ...
... early times in the Galaxy. In particular the abundance patterns of elements with atomic number z ≤ 13 may shed light on the properties of stars that early on enriched parts of the star-forming gas with the rest-products of hydrogen-burning at high temperatures. Aims. We analyse and discuss the chemi ...
The Lost Zodiac - Interactive Stars
... We are often linked to one another through the myths which rule our lives and through our inner quests for wholeness. Our myth may resonate with that of another person's because it describes a similar journey of discovery. Sometimes, our 'story' may be part of the same mythic pattern, or cycle of st ...
... We are often linked to one another through the myths which rule our lives and through our inner quests for wholeness. Our myth may resonate with that of another person's because it describes a similar journey of discovery. Sometimes, our 'story' may be part of the same mythic pattern, or cycle of st ...
n,n - Osaka University
... Furthermore, a non-zero 13 (which is very difficult to measure) could produce an additional enhancement in the high energy ne’s. RESULT: the ne’s detected by OMNIS will be high-energy, so reflect the energy distribution of the nm’s and nt’s emitted from the core of the star. This results from OMNIS ...
... Furthermore, a non-zero 13 (which is very difficult to measure) could produce an additional enhancement in the high energy ne’s. RESULT: the ne’s detected by OMNIS will be high-energy, so reflect the energy distribution of the nm’s and nt’s emitted from the core of the star. This results from OMNIS ...
Spectroscopy – Lecture 1
... that the result fails to accord with observation. The proper course is to find the spectral distribution of the emergent radiation by treating each wavelength separately using its own proper values of j and k.“ ...
... that the result fails to accord with observation. The proper course is to find the spectral distribution of the emergent radiation by treating each wavelength separately using its own proper values of j and k.“ ...
CORALIE-ELODIE new planets and planetary systems. Looking for
... The properties of HD 168443, if not due to an unlikely orbital plane inclination for both objects, set very interesting questions on the possible formation of such systems. The massive inner planet and the low-mass brown-dwarf companion are located well within the ice limit of the young protoplaneta ...
... The properties of HD 168443, if not due to an unlikely orbital plane inclination for both objects, set very interesting questions on the possible formation of such systems. The massive inner planet and the low-mass brown-dwarf companion are located well within the ice limit of the young protoplaneta ...
Main sequence
In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell. Stars on this band are known as main-sequence stars or ""dwarf"" stars.After a star has formed, it generates thermal energy in the dense core region through the nuclear fusion of hydrogen atoms into helium. During this stage of the star's lifetime, it is located along the main sequence at a position determined primarily by its mass, but also based upon its chemical composition and other factors. All main-sequence stars are in hydrostatic equilibrium, where outward thermal pressure from the hot core is balanced by the inward pressure of gravitational collapse from the overlying layers. The strong dependence of the rate of energy generation in the core on the temperature and pressure helps to sustain this balance. Energy generated at the core makes its way to the surface and is radiated away at the photosphere. The energy is carried by either radiation or convection, with the latter occurring in regions with steeper temperature gradients, higher opacity or both.The main sequence is sometimes divided into upper and lower parts, based on the dominant process that a star uses to generate energy. Stars below about 1.5 times the mass of the Sun (or 1.5 solar masses (M☉)) primarily fuse hydrogen atoms together in a series of stages to form helium, a sequence called the proton–proton chain. Above this mass, in the upper main sequence, the nuclear fusion process mainly uses atoms of carbon, nitrogen and oxygen as intermediaries in the CNO cycle that produces helium from hydrogen atoms. Main-sequence stars with more than two solar masses undergo convection in their core regions, which acts to stir up the newly created helium and maintain the proportion of fuel needed for fusion to occur. Below this mass, stars have cores that are entirely radiative with convective zones near the surface. With decreasing stellar mass, the proportion of the star forming a convective envelope steadily increases, whereas main-sequence stars below 0.4 M☉ undergo convection throughout their mass. When core convection does not occur, a helium-rich core develops surrounded by an outer layer of hydrogen.In general, the more massive a star is, the shorter its lifespan on the main sequence. After the hydrogen fuel at the core has been consumed, the star evolves away from the main sequence on the HR diagram. The behavior of a star now depends on its mass, with stars below 0.23 M☉ becoming white dwarfs directly, whereas stars with up to ten solar masses pass through a red giant stage. More massive stars can explode as a supernova, or collapse directly into a black hole.