Paper
... Because of the dimness of the star, the evidence presented by Hajduk e al. that Sakurai’s Object has started to heat up again is indirect (Asplund, 2005). The observation conducted by scientists and astronomers suggest that there is a new area inside the old planetary nebula, which requires a stella ...
... Because of the dimness of the star, the evidence presented by Hajduk e al. that Sakurai’s Object has started to heat up again is indirect (Asplund, 2005). The observation conducted by scientists and astronomers suggest that there is a new area inside the old planetary nebula, which requires a stella ...
Is the initial mass function universal?
... Distance of 7 kpc MMT/ARIES AO H and K band data have been obtained. 0”14 resolution obtained ...
... Distance of 7 kpc MMT/ARIES AO H and K band data have been obtained. 0”14 resolution obtained ...
B – V
... 6. Interstellar reddening (extinction): One of the problems of the 1920s was that the observation of O-B stars had red colors. This was later found to be caused by interstellar material. To measure accurate „real“ colors and to put a star in the Hertzprung-Russel diagram this must be corrected ...
... 6. Interstellar reddening (extinction): One of the problems of the 1920s was that the observation of O-B stars had red colors. This was later found to be caused by interstellar material. To measure accurate „real“ colors and to put a star in the Hertzprung-Russel diagram this must be corrected ...
Spots on Ap Stars
... – Do all of a star’s spots have the same temperature? – Do spots have umbra/penumbra structure? – How does a spot temperature evolve as it forms and vanishes? ...
... – Do all of a star’s spots have the same temperature? – Do spots have umbra/penumbra structure? – How does a spot temperature evolve as it forms and vanishes? ...
WIRO: Spectral Analysis P1
... since Jelm was formerly used by the US Forest Service and BLM as a fire lookout station. ...
... since Jelm was formerly used by the US Forest Service and BLM as a fire lookout station. ...
the chromospheres of classical cepheids. 111. a search for transition
... point during rising light, and the emission declines more or less steadily until the next cycle again excites it. At the phase of strongest emission, the flux is comparable to nonvariable stars of similar luminosity and temperature, but at other phases and averaged over the cycle the chromospheric a ...
... point during rising light, and the emission declines more or less steadily until the next cycle again excites it. At the phase of strongest emission, the flux is comparable to nonvariable stars of similar luminosity and temperature, but at other phases and averaged over the cycle the chromospheric a ...
talk
... protocloud. Dynamically this is impossible in general although some integrals of the motion may be preserved, others will be scrambled by dissipation, ...
... protocloud. Dynamically this is impossible in general although some integrals of the motion may be preserved, others will be scrambled by dissipation, ...
quiz 1 Spring 1995
... The top image is of a planetary nebula (with a central white dwarf). It shows the death stage of a small (sunsized) star and Sol will go through this stage in about 5 billion years. Another such nebula is the Ring Nebula in Lyra. The lower image is of a star formation in the Eagle Nebula in Serpens. ...
... The top image is of a planetary nebula (with a central white dwarf). It shows the death stage of a small (sunsized) star and Sol will go through this stage in about 5 billion years. Another such nebula is the Ring Nebula in Lyra. The lower image is of a star formation in the Eagle Nebula in Serpens. ...
Presentazione di PowerPoint
... In conclusion the intensity level of the CCD is linear up to the saturation limit, but there is a spilling of charges well before the saturation if single pixels are exposed A practical suggestion: ...
... In conclusion the intensity level of the CCD is linear up to the saturation limit, but there is a spilling of charges well before the saturation if single pixels are exposed A practical suggestion: ...
Variability of Be stars
... ~200 Be stars are currently known among 1660 B-type stars brighter than V=6.5 mag ...
... ~200 Be stars are currently known among 1660 B-type stars brighter than V=6.5 mag ...
Alien Worlds Discovered
... About twice the mass of our Sun 100 to 300 million years old A coronagraph on the Hubble Space Telescope was used to block the star’s light in this picture so we can see the disc of material around it Planets are somewhere in size between Neptune and 3 times the size of Jupiter ...
... About twice the mass of our Sun 100 to 300 million years old A coronagraph on the Hubble Space Telescope was used to block the star’s light in this picture so we can see the disc of material around it Planets are somewhere in size between Neptune and 3 times the size of Jupiter ...
7.1 Gravitational Potential Energy
... an insufficient number of particles would penetrate the Coulomb barrier in classical physics to power the Sun’s luminosity. Quantum-mechanically, however, the two nuclei may find themselves within range of the strong nuclear force even if their kinetic energy is insufficient to overcome the Coulomb ...
... an insufficient number of particles would penetrate the Coulomb barrier in classical physics to power the Sun’s luminosity. Quantum-mechanically, however, the two nuclei may find themselves within range of the strong nuclear force even if their kinetic energy is insufficient to overcome the Coulomb ...
UvA-DARE (Digital Academic Repository)
... withh the previous accretion of matter with high angular momentum.(after Habets, 1985). materiall present around these stars, but, probably due to its much lower luminosity, the star of laterr spectral type is no longer able to produce Ha emission. Whenn Be stars are in an 'off' phase, as far as we ...
... withh the previous accretion of matter with high angular momentum.(after Habets, 1985). materiall present around these stars, but, probably due to its much lower luminosity, the star of laterr spectral type is no longer able to produce Ha emission. Whenn Be stars are in an 'off' phase, as far as we ...
18-Feb-2015 - Institute of Astronomy
... problem to explain. In March and April 2012, amateur astronomers reported observing a towering plume of gas stretching up to altitudes over 250 km, well into the thin upper reaches of the Martian atmosphere. Each time the plume took less than 10 hours to develop, and then persisted for about 10 days ...
... problem to explain. In March and April 2012, amateur astronomers reported observing a towering plume of gas stretching up to altitudes over 250 km, well into the thin upper reaches of the Martian atmosphere. Each time the plume took less than 10 hours to develop, and then persisted for about 10 days ...
Stellar Activity
... – Young stars show changes in mean brightness of several % from changes in surface markings, both bright and dark, but brightness varies inversely with chromospheric activity – Hyades show year-to-year brightness changes of order 0.04 mag over times of several years ...
... – Young stars show changes in mean brightness of several % from changes in surface markings, both bright and dark, but brightness varies inversely with chromospheric activity – Hyades show year-to-year brightness changes of order 0.04 mag over times of several years ...
Activity Book Level 4
... 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. More massive stars can fuse heavier elements alo ...
... 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. More massive stars can fuse heavier elements alo ...
What is the Universe made of?
... dwarf, the effect is known as gravitational micro-lensing. By observing many stars over a period of time to see how their appearance changes, scientists hope to detect the presence of massive objects lying between the Earth and the stars – objects that could not normally be detected. ...
... dwarf, the effect is known as gravitational micro-lensing. By observing many stars over a period of time to see how their appearance changes, scientists hope to detect the presence of massive objects lying between the Earth and the stars – objects that could not normally be detected. ...
Astro-figer
... During this year, the astronomers involved with the Massive Star research project have proposed and won observation time targeting young stellar clusters throughout the Galaxy. The Milky Way study project group meets on a weekly basis to plan and discuss their scientific research. The goals of the p ...
... During this year, the astronomers involved with the Massive Star research project have proposed and won observation time targeting young stellar clusters throughout the Galaxy. The Milky Way study project group meets on a weekly basis to plan and discuss their scientific research. The goals of the p ...
The DB gap and a new class of pulsating white dwarfs
... of white dwarfs with helium dominant atmospheres are described and a new class of pulsating white dwarfs, named the hot-DAV stars, is predicted from these scenarios. One pulsating DA white dwarf, being consistent with the prediction, has been discovered indeed. ...
... of white dwarfs with helium dominant atmospheres are described and a new class of pulsating white dwarfs, named the hot-DAV stars, is predicted from these scenarios. One pulsating DA white dwarf, being consistent with the prediction, has been discovered indeed. ...
18.9 NOTES What are constellations? Objective: Explain what
... Different constellations and star groups appear over head at different times of the year. The ones visible in the Northern Hemisphere are different from those visible in the Southern Hemisphere. Though stars are relatively stationary, it is the movements of the Earth that make it look as if the star ...
... Different constellations and star groups appear over head at different times of the year. The ones visible in the Northern Hemisphere are different from those visible in the Southern Hemisphere. Though stars are relatively stationary, it is the movements of the Earth that make it look as if the star ...
Eclipsing binary stars
... position of the stars. The shape and amplitude of the curve depends upon the eccentricity of the orbit and on the angle from which we observe the binary (inclination). If the plane of the star system lies in the line of sight of the observer (i = 90◦ ) and the orbit is circular, then the radial velo ...
... position of the stars. The shape and amplitude of the curve depends upon the eccentricity of the orbit and on the angle from which we observe the binary (inclination). If the plane of the star system lies in the line of sight of the observer (i = 90◦ ) and the orbit is circular, then the radial velo ...
ASTRONOMY 220C ADVANCED STAGES OF
... code - MESA - for projects. In general, the anticipated course material is given in outline form below, but you can expect some alterations as we go along. The course will begin with material that is “classical” in nature, but advance, by mid-quarter to more current, and consequently less certain, r ...
... code - MESA - for projects. In general, the anticipated course material is given in outline form below, but you can expect some alterations as we go along. The course will begin with material that is “classical” in nature, but advance, by mid-quarter to more current, and consequently less certain, r ...
Stellar populations and dynamics in the Milky Way galaxy
... in this sense meaning that the timescale for collapse is comparable to an orbital or a dynamical timescale, which is of the order of 108 years. It should be noted that Isobe (1974) came to the opposite conclusion from his analysis of the ELS data, and favoured a slow collapse, while Yoshii and Saio ...
... in this sense meaning that the timescale for collapse is comparable to an orbital or a dynamical timescale, which is of the order of 108 years. It should be noted that Isobe (1974) came to the opposite conclusion from his analysis of the ELS data, and favoured a slow collapse, while Yoshii and Saio ...
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.