![Interferometric Doppler Imaging of Chemically Peculiar stars](http://s1.studyres.com/store/data/005884851_1-c5127940c1dbaf71f2dd5c04986727c2-300x300.png)
Interferometric Doppler Imaging of Chemically Peculiar stars
... All the F stars can be resolved at 1 μm with baselines ≥ 100 m F stars are in the “sweet spot” for angular diameter and hence age measurement: they are bright, near to us, their evolutionary tracks are reliable, and they are still above ZAMS. ...
... All the F stars can be resolved at 1 μm with baselines ≥ 100 m F stars are in the “sweet spot” for angular diameter and hence age measurement: they are bright, near to us, their evolutionary tracks are reliable, and they are still above ZAMS. ...
The far future of exoplanet direct characterization
... Beyond standard biosignatures, another type of signal far from equilibrium can be seen as technosignatures, that is, spectral features that cannot be explained by complex organic chemistry, such as laser emissions. In the present state of our knowledge, we cannot eliminate these signals a priori, th ...
... Beyond standard biosignatures, another type of signal far from equilibrium can be seen as technosignatures, that is, spectral features that cannot be explained by complex organic chemistry, such as laser emissions. In the present state of our knowledge, we cannot eliminate these signals a priori, th ...
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 ...
L7 - QUB Astrophysics Research Centre
... interactions between the elements and photons of different frequencies. This requires an enormous amount of calculation and is beyond the scope of this course. When it has been done, the results are usually approximated by the ...
... interactions between the elements and photons of different frequencies. This requires an enormous amount of calculation and is beyond the scope of this course. When it has been done, the results are usually approximated by the ...
Neutron Density and Neutron Source Determination in Barium
... neutron density also in only two. In order to extend such studies to other members of this important stellar class, spectroscopic observations of a large number of both northern and Southern hemisphere Ba 1I stars were obtained. This work was carried out in collaboration with O. L. Lambert at the Un ...
... neutron density also in only two. In order to extend such studies to other members of this important stellar class, spectroscopic observations of a large number of both northern and Southern hemisphere Ba 1I stars were obtained. This work was carried out in collaboration with O. L. Lambert at the Un ...
powerpoint file - QUB Astrophysics Research Centre
... central part of the curve (corresponding to close to a solar mass) is approximated by a power law, it has an exponent of approximately 5. Which is in good agreement with the value of 5.46 above. Similarly the lower part of the main-sequence on the observed L-Te diagram (HR diagram) is well represent ...
... central part of the curve (corresponding to close to a solar mass) is approximated by a power law, it has an exponent of approximately 5. Which is in good agreement with the value of 5.46 above. Similarly the lower part of the main-sequence on the observed L-Te diagram (HR diagram) is well represent ...
A SUMMARY OF SELF
... 1. Experimental information about cross sections for astrophysically important reactions is often limited even for well studied nuclear reactions. Explain why. 2. Experimental cross sections are often available for reactions related to explosive burning. What is the reason for this? 3. The possibili ...
... 1. Experimental information about cross sections for astrophysically important reactions is often limited even for well studied nuclear reactions. Explain why. 2. Experimental cross sections are often available for reactions related to explosive burning. What is the reason for this? 3. The possibili ...
Synthetic Stellar Populations Encyclopedia of Astronomy & Astrophysics eaa.iop.org Guy Worthey
... they explode in supernovae explosions. Low-mass stars have entirely different post-main-sequence evolution. They evolve up a ‘red giant branch’ as they fuse hydrogen in a shell around the helium core. At log L ≈ 3.4, the helium reaches ignition temperature and the star immediately adjusts its struct ...
... they explode in supernovae explosions. Low-mass stars have entirely different post-main-sequence evolution. They evolve up a ‘red giant branch’ as they fuse hydrogen in a shell around the helium core. At log L ≈ 3.4, the helium reaches ignition temperature and the star immediately adjusts its struct ...
(Relative) Distances from the HST Snapshot Database
... For stars with T>23.000K, as a consequence of the larger surface gravity and longer central He burning lifetime, one expects that atomic diffusion becomes more and more efficent in decreasing the envelope He abundance, implying the quenching of the HeII convection. At the same time, larger effective ...
... For stars with T>23.000K, as a consequence of the larger surface gravity and longer central He burning lifetime, one expects that atomic diffusion becomes more and more efficent in decreasing the envelope He abundance, implying the quenching of the HeII convection. At the same time, larger effective ...
Habitability of extrasolar planets and tidal spin
... planet has the mass of the Earth and we choose Q = 100 and the tidal Love number of degree two k2 = 0.3 (see left panel of Fig. 2 for a variation of Q by a factor of 2). The IHZ is shaded blue and regions with tero > 1 Gyr, which is the order of magnitude of the time life required to appear on Earth ...
... planet has the mass of the Earth and we choose Q = 100 and the tidal Love number of degree two k2 = 0.3 (see left panel of Fig. 2 for a variation of Q by a factor of 2). The IHZ is shaded blue and regions with tero > 1 Gyr, which is the order of magnitude of the time life required to appear on Earth ...
On the binding energy of the common envelope - UvA-DARE
... The entropy profile for the 10 M star is plotted as a solid line in the third panel. Here “entropy” refers to the local specific entropy per baryon in units of the Boltzmann constant. The arrow indicates the sharp onset of the flat entropy gradient – another criterion for determining the bifurcatio ...
... The entropy profile for the 10 M star is plotted as a solid line in the third panel. Here “entropy” refers to the local specific entropy per baryon in units of the Boltzmann constant. The arrow indicates the sharp onset of the flat entropy gradient – another criterion for determining the bifurcatio ...
UV-Optical Colors as Probes of Early-Type Galaxy Evolution
... If SN too low or galaxies lack four emission lines, radio treatment is applied Objects observed in the GALEX and overlapping radio surveys (FIRST,NVSS) with radio luminosities ~1022W Hz-1 discarded as Type II AGN ( empirical ) ...
... If SN too low or galaxies lack four emission lines, radio treatment is applied Objects observed in the GALEX and overlapping radio surveys (FIRST,NVSS) with radio luminosities ~1022W Hz-1 discarded as Type II AGN ( empirical ) ...
Dark Matter Capture in the first stars
... of the DM halo. But the halo merges with other objects so that a reasonable guess for the lifetime would be tens to hundreds of millions of years tops… • But you never know! They might exist today (Iocco). • Once the DM runs out, switches to fusion. ...
... of the DM halo. But the halo merges with other objects so that a reasonable guess for the lifetime would be tens to hundreds of millions of years tops… • But you never know! They might exist today (Iocco). • Once the DM runs out, switches to fusion. ...
plato
... • Identification and characterisation of planetary systems - including planets of all masses and sizes on various orbits - around stars of all types and ages - including seismic characterization of planet host stars - in particular rocky planets in habitable zone of solar-like stars ...
... • Identification and characterisation of planetary systems - including planets of all masses and sizes on various orbits - around stars of all types and ages - including seismic characterization of planet host stars - in particular rocky planets in habitable zone of solar-like stars ...
Hot HB stars in globular clusters
... for which the existence of EHB stars has been proven spectroscopically. While the helium abundance of F1-1 is typical for sdB stars (i.e. subsolar), F2-2 surprisingly turned out to be a helium rich star. This is the first time ever that a helium rich sdB star has been reported in a globular cluster. ...
... for which the existence of EHB stars has been proven spectroscopically. While the helium abundance of F1-1 is typical for sdB stars (i.e. subsolar), F2-2 surprisingly turned out to be a helium rich star. This is the first time ever that a helium rich sdB star has been reported in a globular cluster. ...
Astrophysics with the Computer: Propagation of Ionization Fronts in
... A hot star is born in an interstellar gas cloud. At first all the gas (hydrogen and helium) is neutral and therefore oprically thick to the ultraviolet (λ < 91 nm) radiation of the star. Where the radiation hits the gas, a layer will be ionised and hence become optically thin. Thus the stellar photo ...
... A hot star is born in an interstellar gas cloud. At first all the gas (hydrogen and helium) is neutral and therefore oprically thick to the ultraviolet (λ < 91 nm) radiation of the star. Where the radiation hits the gas, a layer will be ionised and hence become optically thin. Thus the stellar photo ...
Origin of the terrestrial planets and the moon
... 1986; Newsom & Palme 1984; Newsom 1986). Late accretion of CI planetesimals rich in PGE is a common explanation for their over-abundance in the upper mantle. The addition of the metallic core of the impactor responsible, in the single impact hypothesis, for the origin of the Moon (Benz et al. 1989) ...
... 1986; Newsom & Palme 1984; Newsom 1986). Late accretion of CI planetesimals rich in PGE is a common explanation for their over-abundance in the upper mantle. The addition of the metallic core of the impactor responsible, in the single impact hypothesis, for the origin of the Moon (Benz et al. 1989) ...
Angular momentum evolution
... • Several thousands of rotational periods now available for solar-type and low-mass stars from ~1 Myr to a ~10 Gyr (0.2-1.2 Msun) • Kepler still expected to yield many more rotational periods for field stars • Several tens of vsini measurements available for VLM stars and brown dwarfs ...
... • Several thousands of rotational periods now available for solar-type and low-mass stars from ~1 Myr to a ~10 Gyr (0.2-1.2 Msun) • Kepler still expected to yield many more rotational periods for field stars • Several tens of vsini measurements available for VLM stars and brown dwarfs ...
GMRT Low Frequency Observations of Extrasolar Planetary Systems
... Based on our knowledge of the situation in the solar system, the level of radio emission from a given magnetised extrasolar planet will be proportional to the stellar-wind ram-pressure flux incident on the planetary magnetosphere. This means that the expected level of radio emission from a given ext ...
... Based on our knowledge of the situation in the solar system, the level of radio emission from a given magnetised extrasolar planet will be proportional to the stellar-wind ram-pressure flux incident on the planetary magnetosphere. This means that the expected level of radio emission from a given ext ...
Giant Metrewave Radio Telescope low
... Before we discuss extrasolar planetary radio emission, it will be useful to review the Jovian low-frequency radio emission. Below a cut-off frequency of ∼40 MHz, the Jovian radio emission is thought to be dominated by cyclotron-maser processes from keV electrons in the auroral regions of the planet. ...
... Before we discuss extrasolar planetary radio emission, it will be useful to review the Jovian low-frequency radio emission. Below a cut-off frequency of ∼40 MHz, the Jovian radio emission is thought to be dominated by cyclotron-maser processes from keV electrons in the auroral regions of the planet. ...
The Sun The Sun is a very typical main sequence star. It contains 100
... every 11 years. Sunspots are regions where intense columns of magne9c flux rise into the solar atmosphere (the atmosphere is cooler in the sunspots because the magne9c field causes the gas to expa ...
... every 11 years. Sunspots are regions where intense columns of magne9c flux rise into the solar atmosphere (the atmosphere is cooler in the sunspots because the magne9c field causes the gas to expa ...
ET_at_Science_Cafe
... Need Pwr ~10-6 Lceph . Few day Cepheid, would need 1028 J! Could be much less needed… have not done studies. Not useful for now. Not to melt, need accelerator at r>100 AU, capture radiation from area ~0.1AU2 Accelerators are efficient, well known physics at lower powers, but need large technology ex ...
... Need Pwr ~10-6 Lceph . Few day Cepheid, would need 1028 J! Could be much less needed… have not done studies. Not useful for now. Not to melt, need accelerator at r>100 AU, capture radiation from area ~0.1AU2 Accelerators are efficient, well known physics at lower powers, but need large technology ex ...
Lecture 15
... • Although they look close together in the night sky, stars are very far apart from each other – Remember that the next closest star to the Sun is 4.3 light-years – That’s 25 trillion miles! ...
... • Although they look close together in the night sky, stars are very far apart from each other – Remember that the next closest star to the Sun is 4.3 light-years – That’s 25 trillion miles! ...
Planetary nebula
![](https://commons.wikimedia.org/wiki/Special:FilePath/NGC6543.jpg?width=300)
A planetary nebula, often abbreviated as PN or plural PNe, is a kind of emission nebula consisting of an expanding glowing shell of ionized gas ejected from old red giant stars late in their lives. The word ""nebula"" is Latin for mist or cloud and the term ""planetary nebula"" is a misnomer that originated in the 1780s with astronomer William Herschel because when viewed through his telescope, these objects appeared to him to resemble the rounded shapes of planets. Herschel's name for these objects was popularly adopted and has not been changed. They are a relatively short-lived phenomenon, lasting a few tens of thousands of years, compared to a typical stellar lifetime of several billion years.A mechanism for formation of most planetary nebulae is thought to be the following: at the end of the star's life, during the red giant phase, the outer layers of the star are expelled by strong stellar winds. Eventually, after most of the red giant's atmosphere is dissipated, the exposed hot, luminous core emits ultraviolet radiation to ionize the ejected outer layers of the star. Absorbed ultraviolet light energises the shell of nebulous gas around the central star, appearing as a bright coloured planetary nebula at several discrete visible wavelengths.Planetary nebulae may play a crucial role in the chemical evolution of the Milky Way, returning material to the interstellar medium from stars where elements, the products of nucleosynthesis (such as carbon, nitrogen, oxygen and neon), have been created. Planetary nebulae are also observed in more distant galaxies, yielding useful information about their chemical abundances.In recent years, Hubble Space Telescope images have revealed many planetary nebulae to have extremely complex and varied morphologies. About one-fifth are roughly spherical, but the majority are not spherically symmetric. The mechanisms which produce such a wide variety of shapes and features are not yet well understood, but binary central stars, stellar winds and magnetic fields may play a role.