![The diameter of the CoRoT target HD 49933](http://s1.studyres.com/store/data/015024093_1-d43f24e07c6aa59cee42be68e22ada7b-300x300.png)
The diameter of the CoRoT target HD 49933
... using the VEGA instrument of the CHARA Array and the instrument CLIMB (Sturmann et al. 2010) for 3T group delay tracking. The telescopes E1, E2, and W2 were used giving access to ground baselines of 66, 156, and 221 m. The seeing was stable with a value of r0 between 10 and 13 cm. For the absolute c ...
... using the VEGA instrument of the CHARA Array and the instrument CLIMB (Sturmann et al. 2010) for 3T group delay tracking. The telescopes E1, E2, and W2 were used giving access to ground baselines of 66, 156, and 221 m. The seeing was stable with a value of r0 between 10 and 13 cm. For the absolute c ...
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 ...
Can Planets survive Stellar Evolution?
... mostly on the stellar core mass (Paczyński 1971; Iben & Renzini 1983; Vassiliadis & Wood 1994; Iben 1995). The stellar luminosity during this phase is within the range 3.5 to 23 ×103 L⊙ (for the lowest 0.56 and highest 0.9 M⊙ mass remnant, respectively) and the stellar temperature can reach 100 000 ...
... mostly on the stellar core mass (Paczyński 1971; Iben & Renzini 1983; Vassiliadis & Wood 1994; Iben 1995). The stellar luminosity during this phase is within the range 3.5 to 23 ×103 L⊙ (for the lowest 0.56 and highest 0.9 M⊙ mass remnant, respectively) and the stellar temperature can reach 100 000 ...
GALAXY FORMATION AND CLUSTER FORMATION Richard B
... compact than typical present-day irregular or spiral galaxies, since a higher star formation rate requires a higher mean density (Larson 1977). Typical irregular or spiral galaxies also do not make clusters as massive as typical globular clusters, so they cannot serve as suitable prototypes for the ...
... compact than typical present-day irregular or spiral galaxies, since a higher star formation rate requires a higher mean density (Larson 1977). Typical irregular or spiral galaxies also do not make clusters as massive as typical globular clusters, so they cannot serve as suitable prototypes for the ...
THE LUYINOSITY VARIABILITY OF SOLAR
... sequence, with a rotation period of a few days, or it may undergo a more dramatic spin-up, spin-down episode which, nevertheless, leads the star to almost the same rotational state after 100 Myr or so. Which path the young Sun took is probably unknowable but, in any case, left no strong mark on its ...
... sequence, with a rotation period of a few days, or it may undergo a more dramatic spin-up, spin-down episode which, nevertheless, leads the star to almost the same rotational state after 100 Myr or so. Which path the young Sun took is probably unknowable but, in any case, left no strong mark on its ...
The binary fraction of the young cluster NGC 1818 in the Large
... too crowded and their distances too great, so that their member stars are too faint to be examined individually for binarity. Fortunately, there is an alternative approach, i.e., by means of an artificial-star-test technique, which allows us to estimate the binary fractions in crowded environments. ...
... too crowded and their distances too great, so that their member stars are too faint to be examined individually for binarity. Fortunately, there is an alternative approach, i.e., by means of an artificial-star-test technique, which allows us to estimate the binary fractions in crowded environments. ...
Adiabatic evolution of mass-losing stars
... The previous works generally assumed comparable masses of the two objects in the binary system and an unchanging distance between them throughout the process. In this paper, we will use real stellar models to study how stars respond under adiabatic mass-loss on a time-scale slower than the dynamical ...
... The previous works generally assumed comparable masses of the two objects in the binary system and an unchanging distance between them throughout the process. In this paper, we will use real stellar models to study how stars respond under adiabatic mass-loss on a time-scale slower than the dynamical ...
Invited speakers
... solar planets display highly elliptical orbits, our models include changes in angular velocity and orbital distance resulting from such elliptical orbits. Current Earth based photometry is limited to a precision of about 100ppm of the parent's stars luminosity due to atmospheric extinction. However, ...
... solar planets display highly elliptical orbits, our models include changes in angular velocity and orbital distance resulting from such elliptical orbits. Current Earth based photometry is limited to a precision of about 100ppm of the parent's stars luminosity due to atmospheric extinction. However, ...
The Big Bang and Stellar Evolution
... supposedly faraway quasars (which we will discuss later), some of which are dated at 15 billion light-years, since they have a redshift of 400 percent. That would make them 15 billion years old, which is too old to accommodate the theory. It doesn’t take a nuclear scientist to figure out the math in ...
... supposedly faraway quasars (which we will discuss later), some of which are dated at 15 billion light-years, since they have a redshift of 400 percent. That would make them 15 billion years old, which is too old to accommodate the theory. It doesn’t take a nuclear scientist to figure out the math in ...
Velocity dispersion around ellipticals in MOND
... This model is very successful on a galactic scale; in particular, it explains a large number of rotation curves of galaxies, with some exceptions (Gentile et al. 2004), and naturally the Tully-Fisher relation, (e.g. Sanders & McGaugh 2002). While the dark matter problem is observationally very clear ...
... This model is very successful on a galactic scale; in particular, it explains a large number of rotation curves of galaxies, with some exceptions (Gentile et al. 2004), and naturally the Tully-Fisher relation, (e.g. Sanders & McGaugh 2002). While the dark matter problem is observationally very clear ...
Dark Matter Spiral Structure Basic Galaxy Morphology Disk Galaxy Rotation Curves:
... High luminosity density " Low lum. dens. … etc. But, for example, masses, luminosities, sizes, etc., do not correlate well with the Hubble type: at every type there is a large spread in these fundamental properties. ...
... High luminosity density " Low lum. dens. … etc. But, for example, masses, luminosities, sizes, etc., do not correlate well with the Hubble type: at every type there is a large spread in these fundamental properties. ...
The Initial Mass Function (IMF) Continued
... • Some are very strongly centrally concentrated while others are not • Integrated light has a spectral type ranging from F3 to G5: most of the variation is due to the variation in metallicity {redder = more metal-rich} • Milky Way clusters have a relatively small age range (all old) but other galaxi ...
... • Some are very strongly centrally concentrated while others are not • Integrated light has a spectral type ranging from F3 to G5: most of the variation is due to the variation in metallicity {redder = more metal-rich} • Milky Way clusters have a relatively small age range (all old) but other galaxi ...
Article PDF - IOPscience
... consistent with a random distribution in terms of sky position. In Figure 2, we show the Kepler magnitude of the stars as a function of estimated distance; drawing upon Huber et al. 2014, a distance modulus is obtained from the spectral type implied from the effective temperature and known surface g ...
... consistent with a random distribution in terms of sky position. In Figure 2, we show the Kepler magnitude of the stars as a function of estimated distance; drawing upon Huber et al. 2014, a distance modulus is obtained from the spectral type implied from the effective temperature and known surface g ...
lecture27
... What does careful study of our Milky Way Galaxy tell us about galaxy formation? • The Milky Way’s halo stars are very old and their orbits have random orientations, suggesting that they did indeed form before the protogalactic cloud collapsed into a disk. The low abundances of heavy elements in halo ...
... What does careful study of our Milky Way Galaxy tell us about galaxy formation? • The Milky Way’s halo stars are very old and their orbits have random orientations, suggesting that they did indeed form before the protogalactic cloud collapsed into a disk. The low abundances of heavy elements in halo ...
Presentation in PDF format.
... O stars: >20 M The brightest main-sequence stars. O stars have convective cores and radiative envelopes. Hydrogen-burning is by the CNO-cycle. O stars are always observed close to sites of current or recent star formation. Because of their high luminosities, O stars have very strong stellar winds, ...
... O stars: >20 M The brightest main-sequence stars. O stars have convective cores and radiative envelopes. Hydrogen-burning is by the CNO-cycle. O stars are always observed close to sites of current or recent star formation. Because of their high luminosities, O stars have very strong stellar winds, ...
110 - Institute for Astronomy
... E-mail contact: [email protected] Evidence suggests that some masers associated with massive protostars may originate in the outer regions of large disks, at radii of 100’s to 1000’s of AU from the central mass. This is particularly true for methanol (CH3 OH), where linear distributions of m ...
... E-mail contact: [email protected] Evidence suggests that some masers associated with massive protostars may originate in the outer regions of large disks, at radii of 100’s to 1000’s of AU from the central mass. This is particularly true for methanol (CH3 OH), where linear distributions of m ...
Pre-main sequence evolution
... 1. Pre-main sequence evolution is driven by changes in temperature and density, which lead to changes in the dominant opacity contribution. => Stars alternate between convective and radiative phases. 2. The exact path of a PMS star in the Hertzsprung-Russel-Diagram, i.e. its luminosity-temperature e ...
... 1. Pre-main sequence evolution is driven by changes in temperature and density, which lead to changes in the dominant opacity contribution. => Stars alternate between convective and radiative phases. 2. The exact path of a PMS star in the Hertzsprung-Russel-Diagram, i.e. its luminosity-temperature e ...
low surface brightness galaxies
... When this infall happens, we assume that the galaxy is stripped of its hot gas reservoir so it is no longer able to accrete fresh material for star formation. The galaxy then rapidly consumes its cold gas moving towards the red sequence. ...
... When this infall happens, we assume that the galaxy is stripped of its hot gas reservoir so it is no longer able to accrete fresh material for star formation. The galaxy then rapidly consumes its cold gas moving towards the red sequence. ...
The two components of the evolved massive binary LZ Cephei
... typical mass of late-type O stars. The secondary component is chemically more evolved than the primary (which barely shows any sign of CNO processing), with strong helium and nitrogen enhancements as well as carbon and oxygen depletions. These properties (surface abundances and mass) are typical of ...
... typical mass of late-type O stars. The secondary component is chemically more evolved than the primary (which barely shows any sign of CNO processing), with strong helium and nitrogen enhancements as well as carbon and oxygen depletions. These properties (surface abundances and mass) are typical of ...
RAPID MASS ACCRETION IN THE SYMBIOTIC STAR AG DRA T
... The temperature of the hot component of AG Dra in the quiescent stage is about 150000 K which is derived from the intensities of He H 4686 and He 14471 relative to Hg obtained on August 5, 1980 (Blair et al., 1983) using the formula of Iijima (1982). The luminosity of the hot component in the ultrav ...
... The temperature of the hot component of AG Dra in the quiescent stage is about 150000 K which is derived from the intensities of He H 4686 and He 14471 relative to Hg obtained on August 5, 1980 (Blair et al., 1983) using the formula of Iijima (1982). The luminosity of the hot component in the ultrav ...
KEPLER-15b: A HOT JUPITER ENRICHED IN
... and a mean bulk density of 0.9 ± 0.2 g cm−3 . The radius of Kepler-15b is smaller than the majority of transiting planets with similar mass and irradiation level. This suggests that the planet is more enriched in heavy elements than most other transiting giant planets. For Kepler-15b we estimate a h ...
... and a mean bulk density of 0.9 ± 0.2 g cm−3 . The radius of Kepler-15b is smaller than the majority of transiting planets with similar mass and irradiation level. This suggests that the planet is more enriched in heavy elements than most other transiting giant planets. For Kepler-15b we estimate a h ...
looking for progenitors of cool Ap stars
... on the MS from a study of the distribution of the rotation periods as a function of the gravity (North 1985), and this has been confirmed recently on the basis of new surface gravities obtained from the Hipparcos data (North 1998a,b). Recently, we have studied the evolutionary state of magnetic Ap s ...
... on the MS from a study of the distribution of the rotation periods as a function of the gravity (North 1985), and this has been confirmed recently on the basis of new surface gravities obtained from the Hipparcos data (North 1998a,b). Recently, we have studied the evolutionary state of magnetic Ap s ...
Post-AGB stars in the Magellanic Clouds and neutron
... from the valley of β stability by more than two or three atomic mass numbers for each given element, and it still proceeds sequentially throughout each value of the proton number. Finally, because the PIE was only included in the postprocessing calculations, we cannot evaluate its feedback on the st ...
... from the valley of β stability by more than two or three atomic mass numbers for each given element, and it still proceeds sequentially throughout each value of the proton number. Finally, because the PIE was only included in the postprocessing calculations, we cannot evaluate its feedback on the st ...
Core-Halo Age Gradients and Star Formation in the Orion Nebula
... clusters. Calculating median ages and their confidence intervals for different subregions of interest within these clusters, allowed the discovery of cluster core-halo age gradients (§3.1). We use subsamples of MYStIX PMS stars with available AgeJX estimates. The stars have been stratified by ellipt ...
... clusters. Calculating median ages and their confidence intervals for different subregions of interest within these clusters, allowed the discovery of cluster core-halo age gradients (§3.1). We use subsamples of MYStIX PMS stars with available AgeJX estimates. The stars have been stratified by ellipt ...
Pulsating Stars: Stars that Breathe
... Pulsating stars are a type of variable star in which brightness variations are caused by changes in the area and temperature of the star’s surface layers. Recent evidence suggests that all stars pulsate (if we measure them carefully enough), although the presence of concentrated populations of pulsa ...
... Pulsating stars are a type of variable star in which brightness variations are caused by changes in the area and temperature of the star’s surface layers. Recent evidence suggests that all stars pulsate (if we measure them carefully enough), although the presence of concentrated populations of pulsa ...
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.