The Gemini Observatory: Moving into Science Operations
... stars, points lie above profile but clear that with a single offset they’d also fit the profile. This implies no significant error in the assumed contamination estimate. ...
... stars, points lie above profile but clear that with a single offset they’d also fit the profile. This implies no significant error in the assumed contamination estimate. ...
SOUTHERN CONSTELLATION, SEXTANS Sextans constellation
... luminous than the Sun and has a mass three times solar. The star is believed to be about 300 million years old. It is informally considered to be an “equator star,” currently located less than a quarter of a degree south of the celestial equator. In 1900, it was 7 arcminutes north of the equator, bu ...
... luminous than the Sun and has a mass three times solar. The star is believed to be about 300 million years old. It is informally considered to be an “equator star,” currently located less than a quarter of a degree south of the celestial equator. In 1900, it was 7 arcminutes north of the equator, bu ...
High Resolution Observations of Hot Molecular Cores
... Clustering and the Formation of “Early”-Type ...
... Clustering and the Formation of “Early”-Type ...
A Dozen Colliding-Wind X-Ray Binaries in the Star - UvA-DARE
... We analyzed archival Chandra X-ray observations of the central portion of the 30 Doradus region in the Large Magellanic Cloud. The image contains 20 X-ray point sources with luminosities between 5 1032 and 2 1035 ergs s1 (0.2–3.5 keV). A dozen sources have bright WN Wolf-Rayet or spectral type ...
... We analyzed archival Chandra X-ray observations of the central portion of the 30 Doradus region in the Large Magellanic Cloud. The image contains 20 X-ray point sources with luminosities between 5 1032 and 2 1035 ergs s1 (0.2–3.5 keV). A dozen sources have bright WN Wolf-Rayet or spectral type ...
Super and massive AGB stars-IV. Final fates
... probe the mass limits Mup , Mn and Mmass , the minimum masses for the onset of carbon burning, the formation of a neutron star, and the iron core-collapse supernovae respectively, to constrain the white dwarf/electron-capture supernova boundary. We provide a theoretical initial to final mass relatio ...
... probe the mass limits Mup , Mn and Mmass , the minimum masses for the onset of carbon burning, the formation of a neutron star, and the iron core-collapse supernovae respectively, to constrain the white dwarf/electron-capture supernova boundary. We provide a theoretical initial to final mass relatio ...
Rotational effects on the oscillation frequencies of newly born proto
... extensively been studied in recent years after Andersson (1998) pointed out that it is generic for every rotating star, and since the coupling of the r–mode with the current multipoles is strong, it was proposed that this instability plays an important role in nascent neutron stars. In principle, al ...
... extensively been studied in recent years after Andersson (1998) pointed out that it is generic for every rotating star, and since the coupling of the r–mode with the current multipoles is strong, it was proposed that this instability plays an important role in nascent neutron stars. In principle, al ...
Gamma-ray absorption and pair echos at very high
... exist [17]. Utilizing the blazar evolution model of [18] which is consistent with the observed statistics of the blazar population and takes into account aspects such as the blazar spectral sequence and luminosity-dependent evolution (i.e. “cosmic downsizing”), a new study by [19] finds that Fermi ma ...
... exist [17]. Utilizing the blazar evolution model of [18] which is consistent with the observed statistics of the blazar population and takes into account aspects such as the blazar spectral sequence and luminosity-dependent evolution (i.e. “cosmic downsizing”), a new study by [19] finds that Fermi ma ...
A Second Luminous Blue Variable in the Quintuplet Cluster
... which because of its strength and equivalent width appears more suitable than other lines for providing accurate velocity information. The He i 5-4 triplet line, shifted ;240 km s;1 relative to Br , is weak but clearly present. Although the core of the Br line is symmetric, even after allowing fo ...
... which because of its strength and equivalent width appears more suitable than other lines for providing accurate velocity information. The He i 5-4 triplet line, shifted ;240 km s;1 relative to Br , is weak but clearly present. Although the core of the Br line is symmetric, even after allowing fo ...
gravitation - The Physics Cafe
... o lower than at infinity moon is nearer; less gain in GPE from Earth to moon Thus, escape speed would be lower. ...
... o lower than at infinity moon is nearer; less gain in GPE from Earth to moon Thus, escape speed would be lower. ...
Key paper.
... appears more extended than the dust emission, with a brightness profile that is better resolved. Dust probably extends out to the same limits as the gas but, owing to different emissivity properties, it is not readily detectable at such distances from the star. The outer region of the molecular emis ...
... appears more extended than the dust emission, with a brightness profile that is better resolved. Dust probably extends out to the same limits as the gas but, owing to different emissivity properties, it is not readily detectable at such distances from the star. The outer region of the molecular emis ...
Identifying Young far from Giant Stars Molecular Clouds
... other stars do. Thus, even binaries of advanced age can still have a high rotation rate and a large amount of x-ray emission. To rule out contamination, we use other techniques in distinguishing stellar youth, such as lithium abundance. The changes in T Tauri stars' lithium abundance results from th ...
... other stars do. Thus, even binaries of advanced age can still have a high rotation rate and a large amount of x-ray emission. To rule out contamination, we use other techniques in distinguishing stellar youth, such as lithium abundance. The changes in T Tauri stars' lithium abundance results from th ...
Exploration géochimique du Système Solaire
... mass 0.466 ± 0.006 Ms No significant difference, the mass measurement is accurate The best-fit mass (min. S2) is in the 1σ range (not an outlier) ...
... mass 0.466 ± 0.006 Ms No significant difference, the mass measurement is accurate The best-fit mass (min. S2) is in the 1σ range (not an outlier) ...
The Initial Mass Function (IMF) Continued
... • Low metallicity clusters must have formed very early, around z~10-15 and their formation must have been truncated by reionization. The minimum masses that could cool and collapse, ~108 M~ => ~106 M~ in stars, are strongly suggestive of present day GCs. • DM simulations can reproduce many of the pr ...
... • Low metallicity clusters must have formed very early, around z~10-15 and their formation must have been truncated by reionization. The minimum masses that could cool and collapse, ~108 M~ => ~106 M~ in stars, are strongly suggestive of present day GCs. • DM simulations can reproduce many of the pr ...
RESEARCH STATEMENT Chromospheres and winds
... differ from each other and vary between eclipse cycles. Comparisons between the supergiants in ζ Aurigae, 31 Cyg and 32 Cyg will be important to our understanding of evolved stars because their chromospheric features behave quite differently even though nominally the supergiants are very similar in ...
... differ from each other and vary between eclipse cycles. Comparisons between the supergiants in ζ Aurigae, 31 Cyg and 32 Cyg will be important to our understanding of evolved stars because their chromospheric features behave quite differently even though nominally the supergiants are very similar in ...
Turbulent convection in stellar interiors
... • Radiative zone filled with g-modes excited at the boundary layer ...
... • Radiative zone filled with g-modes excited at the boundary layer ...
Targets for Small Telescopes
... secondary. Different observers see the secondary as different colours. The colours I have mentioned previously, Yellow and Pale Yellow/White are consistent with the spectral types, sometimes I see the secondary as having a pale green or emerald tone to it, depending ...
... secondary. Different observers see the secondary as different colours. The colours I have mentioned previously, Yellow and Pale Yellow/White are consistent with the spectral types, sometimes I see the secondary as having a pale green or emerald tone to it, depending ...
Chapter 8 – Continuous Absorption
... – BB, BF, FF transitions – Photodissociation • Most continuous opacity is due to hydrogen in one form or another ...
... – BB, BF, FF transitions – Photodissociation • Most continuous opacity is due to hydrogen in one form or another ...
ex-lup-v3
... •MID-Outburst: The star temperature rises to 6800K and the accretion disk is pushed out >0.2AU. The upper layers of the disk are depleted as are visible from the SED index and we see crystalline silicates. This is either because the upper layer sublimates and are we looking further into the disk whe ...
... •MID-Outburst: The star temperature rises to 6800K and the accretion disk is pushed out >0.2AU. The upper layers of the disk are depleted as are visible from the SED index and we see crystalline silicates. This is either because the upper layer sublimates and are we looking further into the disk whe ...
The Magnitude Scale
... bolometer which is an instrument that measures the increase in temperature in the flux it receives at all wavelengths). In practice, detectors measure an object’s flux within a certain wavelength region defined by the sensitivity of the detector. Astronomers use measurements of an object’s flux ...
... bolometer which is an instrument that measures the increase in temperature in the flux it receives at all wavelengths). In practice, detectors measure an object’s flux within a certain wavelength region defined by the sensitivity of the detector. Astronomers use measurements of an object’s flux ...
The dramatic change of the fossil magnetic field of HD 190073
... (blue thin dashed lines), and the zero-age main-sequence (black dot-dashed line) are also plotted. The birthline taken from Behrend & Maeder (2001) is plotted with a blue thick dashed line. The limit over which the convective envelope is smaller than 1% of the stellar mass, and the CC-birthline (see ...
... (blue thin dashed lines), and the zero-age main-sequence (black dot-dashed line) are also plotted. The birthline taken from Behrend & Maeder (2001) is plotted with a blue thick dashed line. The limit over which the convective envelope is smaller than 1% of the stellar mass, and the CC-birthline (see ...
HMM词性标注
... rate is a maximum possible accretion rate for mass M. This critical rate can easily be exceeded with the models that are not spherically symmetric, such as mass accretion occurs in a disk. （accrete ionized hydrogen gas） The major problem with fuelling a quasar by gravitational accretion is not the e ...
... rate is a maximum possible accretion rate for mass M. This critical rate can easily be exceeded with the models that are not spherically symmetric, such as mass accretion occurs in a disk. （accrete ionized hydrogen gas） The major problem with fuelling a quasar by gravitational accretion is not the e ...
Constraining decaying dark matter with neutron stars
... star transition could occur when the macroscopic deconfinement proceeds via detonation modes to rapidly consume the star [36]. The GRB signal emitted has been estimated in [14] and subsequent emission in cosmic ray channels is also expected [15]. In our galaxy, the supernova rate is about R = 10−2 yr ...
... star transition could occur when the macroscopic deconfinement proceeds via detonation modes to rapidly consume the star [36]. The GRB signal emitted has been estimated in [14] and subsequent emission in cosmic ray channels is also expected [15]. In our galaxy, the supernova rate is about R = 10−2 yr ...
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.