![Theoretical and observational framework Spectroscopic approach](http://s1.studyres.com/store/data/008085780_1-f8da83cd715ffc532c1c775853083eff-300x300.png)
Theoretical and observational framework Spectroscopic approach
... • The presence of fast HB rotators is confirmed and extended to other clusters. • The abundance of fast HB rotators can apparently change from cluster to cluster. • The change in rotational velocity seems to be associated to the onset of diffusive processes in the stellar atmosphere. • Radiative lev ...
... • The presence of fast HB rotators is confirmed and extended to other clusters. • The abundance of fast HB rotators can apparently change from cluster to cluster. • The change in rotational velocity seems to be associated to the onset of diffusive processes in the stellar atmosphere. • Radiative lev ...
IR-excesses around nearby Lambda Boo stars are caused by debris
... 2000). If the mass-loss due to a radiatively driven stellar wind on an AmFm star was on the order of 10−13 M⊙ /yr, then it could produce a Lambda Boo-like signature on the surface because the radiation pressure would be more efficient for heavy metals (Michaud et al. 1983). However, the mass-loss ra ...
... 2000). If the mass-loss due to a radiatively driven stellar wind on an AmFm star was on the order of 10−13 M⊙ /yr, then it could produce a Lambda Boo-like signature on the surface because the radiation pressure would be more efficient for heavy metals (Michaud et al. 1983). However, the mass-loss ra ...
Herbig-Haro jet in the Haro 6–10 system
... of Hα, [O i], [N ii] and [S ii] are prominent. Besides, the absorption line 6708 Å of Li i, typical for PMS stars, is definitely present. The equivalent width of Hα emission is 55.3 Å, which is smaller than estimated by Levreault (70.9 Å), but Hα/[OI] ratio is 11.8: two times higher than the data ...
... of Hα, [O i], [N ii] and [S ii] are prominent. Besides, the absorption line 6708 Å of Li i, typical for PMS stars, is definitely present. The equivalent width of Hα emission is 55.3 Å, which is smaller than estimated by Levreault (70.9 Å), but Hα/[OI] ratio is 11.8: two times higher than the data ...
Stellar Evolution - Astrophysics
... These are usually expressed relative to the solar mass M , the solar radius R and solar luminosity L respectively. In addition, relative abundances of all chemical elements in the photosphere are needed. ...
... These are usually expressed relative to the solar mass M , the solar radius R and solar luminosity L respectively. In addition, relative abundances of all chemical elements in the photosphere are needed. ...
The effects of fly-bys on planetary systems
... other stars. A planetary system orbiting a star that is not a singleton may have had its evolution changed due to interactions with other stars. In Fig. 2 we show the interaction rates in our reference cluster (same cluster as in Fig. 1), but now only for stars with 0.8 M⊙ < m < 1.2 M⊙ . As can be s ...
... other stars. A planetary system orbiting a star that is not a singleton may have had its evolution changed due to interactions with other stars. In Fig. 2 we show the interaction rates in our reference cluster (same cluster as in Fig. 1), but now only for stars with 0.8 M⊙ < m < 1.2 M⊙ . As can be s ...
Astrophysics in a Nutshell, Second Edition
... are supported against further gravitational contraction, even in the absence of nuclear reactions. As a result, the cores of such stars do not heat up to the temperatures required for the synthesis of heavier elements, and at the end of the asymptotic giant phase they remain with a helium/carbon/oxy ...
... are supported against further gravitational contraction, even in the absence of nuclear reactions. As a result, the cores of such stars do not heat up to the temperatures required for the synthesis of heavier elements, and at the end of the asymptotic giant phase they remain with a helium/carbon/oxy ...
Evolution, Mass Loss and Variability of Low and Intermediate
... Mass Loss from Low and Intermediate Mass Stars Significant mass loss occurs in two phases 1. In red giants before large amplitude (Mira) pulsation starts. These mass loss rates are slow (<10-8 Msun/year). This is the dominant form of mass loss in the lowest mass evolved stars – globular cluster sta ...
... Mass Loss from Low and Intermediate Mass Stars Significant mass loss occurs in two phases 1. In red giants before large amplitude (Mira) pulsation starts. These mass loss rates are slow (<10-8 Msun/year). This is the dominant form of mass loss in the lowest mass evolved stars – globular cluster sta ...
The impact of rotation on the line profiles of Wolf
... et al. (2006) performed a flux-convolution with a rotation profile (e.g. Unsöld 1955) in order to reproduce the broad and round emission lines of the Galactic WN2 star WR 2. Hainich et al. (2014), who extensively analyzed 102 WN stars residing in the Large Magellanic Cloud (LMC), also made use of fl ...
... et al. (2006) performed a flux-convolution with a rotation profile (e.g. Unsöld 1955) in order to reproduce the broad and round emission lines of the Galactic WN2 star WR 2. Hainich et al. (2014), who extensively analyzed 102 WN stars residing in the Large Magellanic Cloud (LMC), also made use of fl ...
Galaxies and Their Structure
... from the spectra of over 40 spiral galaxies (at his time people thought the ``spiral nebulae'' were inside the Milky Way). He found that over 90% of the spectra showed redshifts which meant that they were moving away from us. Edwin Hubble and Milton Humason found distances to the spiral nebulae. Whe ...
... from the spectra of over 40 spiral galaxies (at his time people thought the ``spiral nebulae'' were inside the Milky Way). He found that over 90% of the spectra showed redshifts which meant that they were moving away from us. Edwin Hubble and Milton Humason found distances to the spiral nebulae. Whe ...
STABILITY OF THE DIRECTLY IMAGED
... A new era of directly imaged extrasolar planets has produced a three-planet system (Marois et al. 2008), where the masses of the planets have been estimated by untested cooling models. We point out that the nominal circular, face-on orbits of the planets lead to a dynamical instability in ∼ 105 yr, ...
... A new era of directly imaged extrasolar planets has produced a three-planet system (Marois et al. 2008), where the masses of the planets have been estimated by untested cooling models. We point out that the nominal circular, face-on orbits of the planets lead to a dynamical instability in ∼ 105 yr, ...
Paper II - van Werkhoven, Kenworthy and Mamajek (2014)
... where P0 is the nominal period and Ṗ the time-derivative of the period. This model is fitted to the data using the Nelder–Mead fitting algorithm (Nelder & Mead 1965). Our analysis shows that the bestfitting periods and their amplitudes differ significantly from year to year (see Table 1). Furthermo ...
... where P0 is the nominal period and Ṗ the time-derivative of the period. This model is fitted to the data using the Nelder–Mead fitting algorithm (Nelder & Mead 1965). Our analysis shows that the bestfitting periods and their amplitudes differ significantly from year to year (see Table 1). Furthermo ...
The phase diagram of water and the magnetic fields of Uranus and
... (2008), Lorenzen et al. (2009), and French et al. (2010). The ionic (protonic) conductivity is of major importance in water at conditions deep in planetary interiors. It was determined applying the method of Mattsson and Desjarlais (2006) for the calculation of the ionic diffusion coefficients and as ...
... (2008), Lorenzen et al. (2009), and French et al. (2010). The ionic (protonic) conductivity is of major importance in water at conditions deep in planetary interiors. It was determined applying the method of Mattsson and Desjarlais (2006) for the calculation of the ionic diffusion coefficients and as ...
Photometric transit search for planets around cool stars from the
... stellar evolutionary models the detailed treatment of the effects of non-zero magnetic fields on the properties of low-mass stars (e.g., Mullan & McDonald 2001; Ribas 2006; Torres et al. 2010, and references therein), has significant repercussions on the inferred composition of the planet. An import ...
... stellar evolutionary models the detailed treatment of the effects of non-zero magnetic fields on the properties of low-mass stars (e.g., Mullan & McDonald 2001; Ribas 2006; Torres et al. 2010, and references therein), has significant repercussions on the inferred composition of the planet. An import ...
THE KEPLER CLUSTER STUDY: STELLAR ROTATION IN NGC 6811
... planets. The four clusters are NGC 6866 (0.5 Gyr), NGC 6811 (1 Gyr), NGC 6819 (2.5 Gyr), and NGC 6791 (9 Gyr). As coeval, cospatial, and chemically homogeneous collections of stars with a range of masses, for which precise ages can be determined, open clusters are the best opportunity we have for st ...
... planets. The four clusters are NGC 6866 (0.5 Gyr), NGC 6811 (1 Gyr), NGC 6819 (2.5 Gyr), and NGC 6791 (9 Gyr). As coeval, cospatial, and chemically homogeneous collections of stars with a range of masses, for which precise ages can be determined, open clusters are the best opportunity we have for st ...
Galaxy Collisions, Gas Stripping and Star Formation in the Evolution
... 5 Evolution of galaxies in clusters An overabundance of spiral galaxies and an under abundance of S0 galaxies in highredshift clusters, when it is compared to low z clusters, is a consequences of galaxy merger events and of other environmental effects. In ΛDCM cosmological models with Ω0 = 0.4 and Ω ...
... 5 Evolution of galaxies in clusters An overabundance of spiral galaxies and an under abundance of S0 galaxies in highredshift clusters, when it is compared to low z clusters, is a consequences of galaxy merger events and of other environmental effects. In ΛDCM cosmological models with Ω0 = 0.4 and Ω ...
asteroseismological study of massive zz ceti stars with
... stars populating the high-mass component are likely to have carbon–oxygen cores, formed during the stable helium burning phase in the pre-white dwarf evolution. However, evolutionary computations show that stars with stellar mass in the zero age main sequence (ZAMS) of 7 M reach stable carbon igni ...
... stars populating the high-mass component are likely to have carbon–oxygen cores, formed during the stable helium burning phase in the pre-white dwarf evolution. However, evolutionary computations show that stars with stellar mass in the zero age main sequence (ZAMS) of 7 M reach stable carbon igni ...
Kepler-1647b: The Largest And Longest-Period Kepler
... the models of protoplanetary disks and migration history and allows us to discern between an observational bias and a migration pileup (Kley & Haghighipou 2014, 2015). Discoveries of misaligned transiting CBPs such as Kepler-413b (Kostov et al. 2014) and Kepler-453b (Welsh et al. 2015) help determin ...
... the models of protoplanetary disks and migration history and allows us to discern between an observational bias and a migration pileup (Kley & Haghighipou 2014, 2015). Discoveries of misaligned transiting CBPs such as Kepler-413b (Kostov et al. 2014) and Kepler-453b (Welsh et al. 2015) help determin ...
Document
... • For cD galaxies, there is an excess brightness at large radii compared to the r1/4 profile → cD ≈ gE + extended luminous halo • The extended halos of the cD galaxies could be the remains of many small galaxies `swallowed´ by the giant elliptical • The de Vaucouleurs law can be generalized to ellip ...
... • For cD galaxies, there is an excess brightness at large radii compared to the r1/4 profile → cD ≈ gE + extended luminous halo • The extended halos of the cD galaxies could be the remains of many small galaxies `swallowed´ by the giant elliptical • The de Vaucouleurs law can be generalized to ellip ...
Radial transport in the solar nebula: Implications for moderately
... components in chondritic meteorites record a variety of preaccretionary thermal evolution, which argues that materials from different environments and locations were mixed prior to the formation of the chondritic meteorite parent bodies. Among the reasons that the incomplete condensation theory has ...
... components in chondritic meteorites record a variety of preaccretionary thermal evolution, which argues that materials from different environments and locations were mixed prior to the formation of the chondritic meteorite parent bodies. Among the reasons that the incomplete condensation theory has ...
Binary Stars
... Binary Stars may have orbital periods from seconds to hours to thousands of years They may contain stars of all kinds, sizes, and masses They may have circular or elliptical orbits They are believed to have formed together same age (not capture) ...
... Binary Stars may have orbital periods from seconds to hours to thousands of years They may contain stars of all kinds, sizes, and masses They may have circular or elliptical orbits They are believed to have formed together same age (not capture) ...
The observed distribution of spectroscopic binaries from the Anglo
... clearly greater than the duration of the observations, and where periodogram analysis is least effective, we consider only the minimum orbital period in our solutions. Periodograms are shown (Fig. 2) for all the targets where the RV phase coverage is nearly a cycle or more. Where the sampling is spa ...
... clearly greater than the duration of the observations, and where periodogram analysis is least effective, we consider only the minimum orbital period in our solutions. Periodograms are shown (Fig. 2) for all the targets where the RV phase coverage is nearly a cycle or more. Where the sampling is spa ...
Herschel far-infrared observations of the Carina Nebula complex⋆
... Most stars in our Galaxy form in giant molecular clouds, as parts of rich stellar clusters or associations, containing highmass (M > 20 M ) stars. Recent investigations have shown that also our solar system formed close to massive stars, which had important influences on the early evolution of the ...
... Most stars in our Galaxy form in giant molecular clouds, as parts of rich stellar clusters or associations, containing highmass (M > 20 M ) stars. Recent investigations have shown that also our solar system formed close to massive stars, which had important influences on the early evolution of the ...
The Milky Way Laboratory
... • Add more species and improve radiative transfer modeling (JCMT, PI: Kirk). • Measure infall rates toward many more regions. Does it correlate with mass or evolutionary stage? What determines the final mass of a cluster? ...
... • Add more species and improve radiative transfer modeling (JCMT, PI: Kirk). • Measure infall rates toward many more regions. Does it correlate with mass or evolutionary stage? What determines the final mass of a cluster? ...
ExoPlanet News No. 74, November 3rd, 2014 Contents An Electronic Newsletter
... International Journal of Astrobiology, in press (arXiv:1408.5207) Recently, the Kepler Space Telescope has detected several planets in orbit around a close binary star system. These so-called circumbinary planets will experience non-trivial spatial and temporal distributions of radiative flux on the ...
... International Journal of Astrobiology, in press (arXiv:1408.5207) Recently, the Kepler Space Telescope has detected several planets in orbit around a close binary star system. These so-called circumbinary planets will experience non-trivial spatial and temporal distributions of radiative flux on the ...
THE HOBBY-EBERLY TELESCOPE CHEMICAL ABUNDANCES OF
... chain reactions. These nucleosynthesis reactions make it indeed possible for a star to self-enrich its atmosphere with Li, but only for a very short period of time before the freshly produced Li burns again. The enrichment can be quite extreme, however, with Li abundances sometimes 1Y2 dex higher th ...
... chain reactions. These nucleosynthesis reactions make it indeed possible for a star to self-enrich its atmosphere with Li, but only for a very short period of time before the freshly produced Li burns again. The enrichment can be quite extreme, however, with Li abundances sometimes 1Y2 dex higher th ...
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.