The white dwarf population within 40 pc of the Sun
... white dwarfs carries crucial information about the physical processes governing the evolution of the vast majority of stars, and in particular of the total amount of mass lost by low- and intermediate-mas stars during the red giant and asymptotic giant branch evolutionary phases. Also, the populatio ...
... white dwarfs carries crucial information about the physical processes governing the evolution of the vast majority of stars, and in particular of the total amount of mass lost by low- and intermediate-mas stars during the red giant and asymptotic giant branch evolutionary phases. Also, the populatio ...
Rotation, activity, and stellar obliquities in a large uniform sample of
... Maciel 1996), lithium-depleted (Takeda 2007), and deficient in chromospheric activity (Hall et al. 2007, 2009) relative to its putative analogs, but for many of these claims there is conflicting evidence (see, e.g., Hall et al. 2009; Adibekyan et al. 2013) and so it is in some ways unclear, as some ...
... Maciel 1996), lithium-depleted (Takeda 2007), and deficient in chromospheric activity (Hall et al. 2007, 2009) relative to its putative analogs, but for many of these claims there is conflicting evidence (see, e.g., Hall et al. 2009; Adibekyan et al. 2013) and so it is in some ways unclear, as some ...
Influence of the Gould Belt on Interstellar Extinction
... solution gives 12 unknowns: γ, λ0 , ZA , ζA , Z0 , ζ0 , A0 , A1 , A2 , Λ0 , Λ1 , Λ2 . These are chosen so as to minimize the sum of the squares of the residuals of the left-hand and right-hand sides of Eqs. (3). We can estimate some of the unknowns in advance. The inclination γ of the Gould Belt to ...
... solution gives 12 unknowns: γ, λ0 , ZA , ζA , Z0 , ζ0 , A0 , A1 , A2 , Λ0 , Λ1 , Λ2 . These are chosen so as to minimize the sum of the squares of the residuals of the left-hand and right-hand sides of Eqs. (3). We can estimate some of the unknowns in advance. The inclination γ of the Gould Belt to ...
NSDL_WS_1_Astonomy
... of interstellar gas and dust… clouds rotate as they collapse … conserving angular momentum … forming the smaller clumps that will become stars ...
... of interstellar gas and dust… clouds rotate as they collapse … conserving angular momentum … forming the smaller clumps that will become stars ...
Starspots: A Key to the Stellar Dynamo | SpringerLink
... by cyclonic turbulence in the outer convection zone and penetrate the solar atmosphere forming sunspots, plages, network, etc. They further expand into the outer atmosphere and exhibit themselves as highly dynamic coronal loops. Thus, a detailed study of solar activity phenomena reveals the structur ...
... by cyclonic turbulence in the outer convection zone and penetrate the solar atmosphere forming sunspots, plages, network, etc. They further expand into the outer atmosphere and exhibit themselves as highly dynamic coronal loops. Thus, a detailed study of solar activity phenomena reveals the structur ...
The white dwarf population within 40 pc of the Sun
... dwarfs with the observed data is the implementation of the observational selection criteria in the theoretical samples. To account for the observational biases with a high degree of fidelity, we implemented the selection criteria employed by Limoges et al. (2013, 2015) in their analysis of the SUPER ...
... dwarfs with the observed data is the implementation of the observational selection criteria in the theoretical samples. To account for the observational biases with a high degree of fidelity, we implemented the selection criteria employed by Limoges et al. (2013, 2015) in their analysis of the SUPER ...
Silicon isotopic abundance toward evolved stars and its application
... Most of the presolar grains have 29 Si/30 Si ratios around 1.5, but evidence of lower 29 Si/30 Si ratios are also found in presolar SiC grains, for instance, types X2 and Z in Fig. 3. The type Z grains may have originated from a nearby evolved star (see also Zinner et al. 2006). Additionally, the ty ...
... Most of the presolar grains have 29 Si/30 Si ratios around 1.5, but evidence of lower 29 Si/30 Si ratios are also found in presolar SiC grains, for instance, types X2 and Z in Fig. 3. The type Z grains may have originated from a nearby evolved star (see also Zinner et al. 2006). Additionally, the ty ...
An Unbiased Near-infrared Interferometric Survey for Hot
... underlying planetary system. While this would be a very interesting scenario, it is questionable whether all systems observed are likely to meet these constraints. A combination of planetesimaldriven migration and dust trapping could explain the presence of the detected dust. Potential dust-trapping ...
... underlying planetary system. While this would be a very interesting scenario, it is questionable whether all systems observed are likely to meet these constraints. A combination of planetesimaldriven migration and dust trapping could explain the presence of the detected dust. Potential dust-trapping ...
Abstract book
... Title: Density or mass, which control the early stages of the star formation process? Abstract. How do stellar clusters form is a one of the key questions for understanding the physical mechanisms that drive the transformation of cold molecular gas into stars in different environments. In particular ...
... Title: Density or mass, which control the early stages of the star formation process? Abstract. How do stellar clusters form is a one of the key questions for understanding the physical mechanisms that drive the transformation of cold molecular gas into stars in different environments. In particular ...
A Revised DDO Abundance Calibration for Population I Red Giants
... Galactic disk, but also to the more metal-poor stars of the old disk having [Fe/H] between – 0.3 and – 0.8. There are at least three reasons to justify embarking on a new DDO abundance calibration for population IG and Κ giants. First of all, the sample of field and open cluster red giants with abun ...
... Galactic disk, but also to the more metal-poor stars of the old disk having [Fe/H] between – 0.3 and – 0.8. There are at least three reasons to justify embarking on a new DDO abundance calibration for population IG and Κ giants. First of all, the sample of field and open cluster red giants with abun ...
Search For Gas Giants Around Late-m Dwarfs - STARS
... The physical properties of M dwarfs we determined included the identification of neutral atomic lines, the measurement of pseudo-equivalent widths, masses, surface gravity, effective temperature, absolute radial velocities, rotational velocities and rotation periods. The identification of neutral at ...
... The physical properties of M dwarfs we determined included the identification of neutral atomic lines, the measurement of pseudo-equivalent widths, masses, surface gravity, effective temperature, absolute radial velocities, rotational velocities and rotation periods. The identification of neutral at ...
The white dwarf population within 40 pc of the Sun
... white dwarfs carries crucial information about the physical processes that govern the evolution of the vast majority of stars and, in particular, of the total amount of mass lost by low- and intermediate-mass stars during the red giant and asymptotic giant branch evolutionary phases. Also, the popul ...
... white dwarfs carries crucial information about the physical processes that govern the evolution of the vast majority of stars and, in particular, of the total amount of mass lost by low- and intermediate-mass stars during the red giant and asymptotic giant branch evolutionary phases. Also, the popul ...
A cold detached dust envelope around an oxygen-rich Mira
... case (Hashimoto 1994, 1995). (4) Or, some circumstellar mechanisms other than dust grains may produce the infrared excess. For example, strong line emission from circumstellar molecules such as H2 O may cause the reddening. In any case, there must be some physical conditions which are unknown in the ...
... case (Hashimoto 1994, 1995). (4) Or, some circumstellar mechanisms other than dust grains may produce the infrared excess. For example, strong line emission from circumstellar molecules such as H2 O may cause the reddening. In any case, there must be some physical conditions which are unknown in the ...
... In the RRL data base of GEOS (2012) one can find a list of 96 times of maxima and the corresponding O-C diagram built with the ephemerides 2419130.305+0.28779276 E is reproduced in Figure 4. Visual observations show a particularly large scatter at HJD ∼ 2443800 which may be due to their larger uncer ...
The ages of pre-main-sequence stars
... about 100 yr. Such a definition leads to a well-defined age at any point on a track corresponding to a constant mass. For comparison, Fig. 1 shows such a set of pre-main-sequence tracks for M 0:1, 0.2, 0.5, 1 and 2 M(, and isochrones fitted to 50 models in this range. We describe our models in det ...
... about 100 yr. Such a definition leads to a well-defined age at any point on a track corresponding to a constant mass. For comparison, Fig. 1 shows such a set of pre-main-sequence tracks for M 0:1, 0.2, 0.5, 1 and 2 M(, and isochrones fitted to 50 models in this range. We describe our models in det ...
pvb-based star compositions
... portion of magnalium, is particularly bright and burns fiercely, with a tendency to jet. The orange star is adjusted to my taste in colour; if you prefer a different shade, you might want to alter the relative proportions of calcium carbonate and cryolite. The compositions listed in Table 2 are reas ...
... portion of magnalium, is particularly bright and burns fiercely, with a tendency to jet. The orange star is adjusted to my taste in colour; if you prefer a different shade, you might want to alter the relative proportions of calcium carbonate and cryolite. The compositions listed in Table 2 are reas ...
Radiative winds, accretion disks and massive stars physics using
... • Ions which provide the radiative acceleration constitute about only 10-5 of all ions by number (since H and He contribute negligibly to the acceleration since fully ionized) so if a typical ion increases its velocity by 20cm/s, the effective increase per absorption is 2x10-3 cm/s. To accelerate th ...
... • Ions which provide the radiative acceleration constitute about only 10-5 of all ions by number (since H and He contribute negligibly to the acceleration since fully ionized) so if a typical ion increases its velocity by 20cm/s, the effective increase per absorption is 2x10-3 cm/s. To accelerate th ...
Nucleosynthesis and Chemical Evolution of Oxygen
... convective core. The star will then contract until the next burning stage begins. Shell burning occurs when the region outside the formerly convective core contracts and heats to the point that the appropriate nuclear fuel can ignite. With these preliminaries in mind, we may trace the star’s evolut ...
... convective core. The star will then contract until the next burning stage begins. Shell burning occurs when the region outside the formerly convective core contracts and heats to the point that the appropriate nuclear fuel can ignite. With these preliminaries in mind, we may trace the star’s evolut ...
Hunting for Substructure in the Milky Way
... calculating relative abundances of certain elements. Dynamical analysis means looking at the orbits on which the stars move. Combining information from both methods is called chemodynamical analysis and gives the best picture of the star’s history, and subsequently the history of the Milky Way. Stud ...
... calculating relative abundances of certain elements. Dynamical analysis means looking at the orbits on which the stars move. Combining information from both methods is called chemodynamical analysis and gives the best picture of the star’s history, and subsequently the history of the Milky Way. Stud ...
The Evolution of Isotope Ratios in the Milky Way Galaxy
... Isotope ratios have opened a new window into the study of the details of stellar evolution, supernovae, and galactic chemical evolution. We present the evolution of the isotope ratios of elemental abundances (from C to Zn) in the solar neighbourhood, bulge, halo, and thick disk, using chemical evolu ...
... Isotope ratios have opened a new window into the study of the details of stellar evolution, supernovae, and galactic chemical evolution. We present the evolution of the isotope ratios of elemental abundances (from C to Zn) in the solar neighbourhood, bulge, halo, and thick disk, using chemical evolu ...
Angular Momentum Evolution of Young Low
... fast rotation. This suggests a spindown timescale on the order of a few 0.1 gigayears (G.y.) for solar-type stars, as angular momentum is carried away by magnetized winds. The development of a slow rotator sequence and its gradual evolution toward longer periods indeed serves as a basis for main-seq ...
... fast rotation. This suggests a spindown timescale on the order of a few 0.1 gigayears (G.y.) for solar-type stars, as angular momentum is carried away by magnetized winds. The development of a slow rotator sequence and its gradual evolution toward longer periods indeed serves as a basis for main-seq ...
Mass loss of massive stars near the Eddington luminosity by core
... before the core collapse by chance. However, we suggest that, if a SN progenitor is near the Eddington luminosity from several years before the core collapse, the star is not required to be LBVs to enhance the mass loss. The sudden luminosity increase observed in some Type IIn SNe in ∼years to ∼10 d ...
... before the core collapse by chance. However, we suggest that, if a SN progenitor is near the Eddington luminosity from several years before the core collapse, the star is not required to be LBVs to enhance the mass loss. The sudden luminosity increase observed in some Type IIn SNe in ∼years to ∼10 d ...
Test 3 Review Clicker Questions
... a) distance and surface temperature b) luminosity and surface temperature c) distance and luminosity d) mass and age e) distance and color ...
... a) distance and surface temperature b) luminosity and surface temperature c) distance and luminosity d) mass and age e) distance and color ...
The isotopic mixture of barium in the metal-poor
... Magain would give a value of f odd (0.08) close to his value. The FWHM of the Ba II line appears not to be affected by blending lines. Cowley & Frey searched for potential blends that might be disturbing the profile in a solar-like star, concluding that only two transitions Cr I 4553.94 Å and Zr I ...
... Magain would give a value of f odd (0.08) close to his value. The FWHM of the Ba II line appears not to be affected by blending lines. Cowley & Frey searched for potential blends that might be disturbing the profile in a solar-like star, concluding that only two transitions Cr I 4553.94 Å and Zr I ...
Stellar classification
In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Light from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with absorption lines. Each line indicates an ion of a certain chemical element, with the line strength indicating the abundance of that ion. The relative abundance of the different ions varies with the temperature of the photosphere. The spectral class of a star is a short code summarizing the ionization state, giving an objective measure of the photosphere's temperature and density.Most stars are currently classified under the Morgan–Keenan (MK) system using the letters O, B, A, F, G, K, and M, a sequence from the hottest (O type) to the coolest (M type). Each letter class is then subdivided using a numeric digit with 0 being hottest and 9 being coolest (e.g. A8, A9, F0, F1 form a sequence from hotter to cooler). The sequence has been expanded with classes for other stars and star-like objects that do not fit in the classical system, such class D for white dwarfs and class C for carbon stars.In the MK system a luminosity class is added to the spectral class using Roman numerals. This is based on the width of certain absorption lines in the star's spectrum which vary with the density of the atmosphere and so distinguish giant stars from dwarfs. Luminosity class 0 or Ia+ stars for hypergiants, class I stars for supergiants, class II for bright giants, class III for regular giants, class IV for sub-giants, class V for main-sequence stars, class sd for sub-dwarfs, and class D for white dwarfs. The full spectral class for the Sun is then G2V, indicating a main-sequence star with a temperature around 5,800K.