Globular and Open Clusters in our Galaxy
... The overall number of currently known globular clusters in our Galaxy is about 150. They can be find about anywhere in the celestial sphere, but with a significant concentration towards the Milky Way center, which explains why the constellations of Sagittarius, Ophiuchus and Scorpius solely congrega ...
... The overall number of currently known globular clusters in our Galaxy is about 150. They can be find about anywhere in the celestial sphere, but with a significant concentration towards the Milky Way center, which explains why the constellations of Sagittarius, Ophiuchus and Scorpius solely congrega ...
HS 0702+6043: a star showing both short-period p
... variation in HS 0702+6043 is a rotating star spot. Although single sdBs do not generally rotate very rapidly, with only one possible exception (PG 1605+072, but see Kuassivi et al. 2005), the following scenario can be constructed around this possibility. Assuming that the 1 h period corresponds to t ...
... variation in HS 0702+6043 is a rotating star spot. Although single sdBs do not generally rotate very rapidly, with only one possible exception (PG 1605+072, but see Kuassivi et al. 2005), the following scenario can be constructed around this possibility. Assuming that the 1 h period corresponds to t ...
Reprocessing the Hipparcos data of evolved stars
... Hipparcos mission. The parallaxes are in most cases re-computed from the Hipparcos Intermediate Astrometric Data using improved astrometric fits and chromaticity corrections. The K band magnitudes are taken from the literature and from measurements by COBE, and are corrected for interstellar and cir ...
... Hipparcos mission. The parallaxes are in most cases re-computed from the Hipparcos Intermediate Astrometric Data using improved astrometric fits and chromaticity corrections. The K band magnitudes are taken from the literature and from measurements by COBE, and are corrected for interstellar and cir ...
How much radioactive nickel does ASASSN
... Hosokawa et al. 2013). Such large stellar objects may be formed in a two-step process through accretion on the already formed proto-star (Kuiper et al. 2011). However, the uncertainty in mass-loss rates for very massive stars implies large uncertainties in their evolution (Vink 2015). The crucial as ...
... Hosokawa et al. 2013). Such large stellar objects may be formed in a two-step process through accretion on the already formed proto-star (Kuiper et al. 2011). However, the uncertainty in mass-loss rates for very massive stars implies large uncertainties in their evolution (Vink 2015). The crucial as ...
On the onset of runaway stellar collisions in dense star clusters I
... They also found that collisions occur every few ten thousand years, which is roughly the time required for a collision product to reach the main-sequence. Stellar collisions also play an important role in the formation of stellar exotica in young star clusters, such as blue stragglers. If cluster pr ...
... They also found that collisions occur every few ten thousand years, which is roughly the time required for a collision product to reach the main-sequence. Stellar collisions also play an important role in the formation of stellar exotica in young star clusters, such as blue stragglers. If cluster pr ...
Searching for the Secrets of Massive Star Birth
... Introduction: Massive stars play a central role in the evolution of the both the cosmos and the galactic interstellar medium (ISM). The first stars to form in the universe were massive. They were responsible for cosmic re-ionization and its initial chemical enrichment. Massive stars continue to pow ...
... Introduction: Massive stars play a central role in the evolution of the both the cosmos and the galactic interstellar medium (ISM). The first stars to form in the universe were massive. They were responsible for cosmic re-ionization and its initial chemical enrichment. Massive stars continue to pow ...
FLARESTARSINTHEORIONN EBULAREGION SUMARIO Durante
... From what has been said before, in the Orion Nebula region there are at least four different kinds of flare stars: a) typical T Tauri stars in which, during long periods, the strong emission lines of H, CaII and some other bright lines, plus a rather strong ultraviolet continuum, are observed; b) ne ...
... From what has been said before, in the Orion Nebula region there are at least four different kinds of flare stars: a) typical T Tauri stars in which, during long periods, the strong emission lines of H, CaII and some other bright lines, plus a rather strong ultraviolet continuum, are observed; b) ne ...
Turbulent Flow-Driven Molecular Cloud Formation: A Solution to the
... Figure 2 shows a velocity-integrated map in 12 CO (isocontours) and H I (gray-scale) for the velocity range where the CO data has been obtained (−20.33 km s−1 ≤ vLSR ≤ 29.1 km s−1 ). The straight lines indicate the loci of the cuts along which the velocity-position diagrams shown in Figure 3 are mad ...
... Figure 2 shows a velocity-integrated map in 12 CO (isocontours) and H I (gray-scale) for the velocity range where the CO data has been obtained (−20.33 km s−1 ≤ vLSR ≤ 29.1 km s−1 ). The straight lines indicate the loci of the cuts along which the velocity-position diagrams shown in Figure 3 are mad ...
The white dwarf cooling sequence of 47 Tucanae
... – see their Fig. 10 – and prompted them to attribute its origin to some missing piece of physics in all the existing models at moderate temperatures. The results of our population synthesis simulations for our reference model are shown as well and also include the 1σ statistical deviations (upper an ...
... – see their Fig. 10 – and prompted them to attribute its origin to some missing piece of physics in all the existing models at moderate temperatures. The results of our population synthesis simulations for our reference model are shown as well and also include the 1σ statistical deviations (upper an ...
EXCITATION OF RADIAL P-MODES IN THE SUN AND STARS ROBERT STEIN
... compressibility. Excitation decreases at high frequencies because convection lacks high frequency motions. Finally, we apply our formula to the excitation of stellar p-mode oscillations using simulations of nine stars near the main sequence and a cool sub-giant (Section 6). We find that the total ex ...
... compressibility. Excitation decreases at high frequencies because convection lacks high frequency motions. Finally, we apply our formula to the excitation of stellar p-mode oscillations using simulations of nine stars near the main sequence and a cool sub-giant (Section 6). We find that the total ex ...
The P Cygni supergiant [OMN2000] LS1
... close to the photosphere. In such a situation any He/H ratio may fit the observations with an appropiate scaling of the mass loss rate and a small variation of the stellar temperature; this effect is observed in e.g. HD316285 (see Hillier et al. 1998 for a discussion). However, unlike this star, the ...
... close to the photosphere. In such a situation any He/H ratio may fit the observations with an appropiate scaling of the mass loss rate and a small variation of the stellar temperature; this effect is observed in e.g. HD316285 (see Hillier et al. 1998 for a discussion). However, unlike this star, the ...
The white dwarf cooling sequence of 47 Tucanae
... we will only summarize the ingredients which are most relevant for our work. Synthetic main sequence stars are randomly drawn according to the initial mass function of Kroupa et al. (1993). The selected range of masses is that necessary to produce the white dwarf progenitors of 47 Tuc. In particular ...
... we will only summarize the ingredients which are most relevant for our work. Synthetic main sequence stars are randomly drawn according to the initial mass function of Kroupa et al. (1993). The selected range of masses is that necessary to produce the white dwarf progenitors of 47 Tuc. In particular ...
Supervisors
... can be found from the Boltzmann equation (1.12) and the ratios in the n denominator can be computed by using the Saha equation (1.13). The atmospheres of very hot stars cannot be assumed to be in LTE and non-LTE (NLTE) must be used (Przybilla et al., 2011). This is because of the general properties ...
... can be found from the Boltzmann equation (1.12) and the ratios in the n denominator can be computed by using the Saha equation (1.13). The atmospheres of very hot stars cannot be assumed to be in LTE and non-LTE (NLTE) must be used (Przybilla et al., 2011). This is because of the general properties ...
Lithium abundances for 185 main-sequence stars
... resolution spectra of 130 stars and a reanalysis of data for 55 stars from Lambert et al. (1991). The survey takes advantage of improved photometric and spectroscopic determinations of effective temperature and metallicity as well as mass and age derived from Hipparcos absolute magnitudes, offering ...
... resolution spectra of 130 stars and a reanalysis of data for 55 stars from Lambert et al. (1991). The survey takes advantage of improved photometric and spectroscopic determinations of effective temperature and metallicity as well as mass and age derived from Hipparcos absolute magnitudes, offering ...
PDF only - at www.arxiv.org.
... From the morphologies of the clusters obtained by implementing the two clustering algorithms, it is quite evident that they agree well with each other even though the cluster morphologies obtained from DBSCAN are larger. Czernik 20 seems to exhibit a nearly circular morphology whereas NGC 1857 seems ...
... From the morphologies of the clusters obtained by implementing the two clustering algorithms, it is quite evident that they agree well with each other even though the cluster morphologies obtained from DBSCAN are larger. Czernik 20 seems to exhibit a nearly circular morphology whereas NGC 1857 seems ...
Entropy Production of Stars
... be noted that the quantity of entropy production is convenient from the standpoint of theory and calculations but not always easy to determine in experiments: it is measured only indirectly and special conditions of a nonequilibrium system are preferable (for example, isolated or stationary). All th ...
... be noted that the quantity of entropy production is convenient from the standpoint of theory and calculations but not always easy to determine in experiments: it is measured only indirectly and special conditions of a nonequilibrium system are preferable (for example, isolated or stationary). All th ...
The binary fraction of the young cluster NGC 1818 in the Large
... were converted to the standard Johnson/Cousins V and I filters using the transformation solutions of Dolphin (2000). We show the CMD around the cluster’s half-light radius (as defined in HST program GO-7307) in Fig. 2 (left-hand panel) and provide the current-best estimates of a few important cluste ...
... were converted to the standard Johnson/Cousins V and I filters using the transformation solutions of Dolphin (2000). We show the CMD around the cluster’s half-light radius (as defined in HST program GO-7307) in Fig. 2 (left-hand panel) and provide the current-best estimates of a few important cluste ...
Thermohaline mixing and the photospheric composition of low
... Previous investigations are uncertain about the consequences and relevance of the setting in of thermohaline instability at the RGB: while some authors find the mixing rate generated by this process to be enough to reproduce the surface abundances observed, others consider this mechanism to be insuf ...
... Previous investigations are uncertain about the consequences and relevance of the setting in of thermohaline instability at the RGB: while some authors find the mixing rate generated by this process to be enough to reproduce the surface abundances observed, others consider this mechanism to be insuf ...
The Correlation of Lithium and Beryllium in F and G
... we made a survey of bright F and G dwarfs that had not been studied for Li. One objective of that survey was to search for stars with depleted but detectable Li. Then Be observations would be made of suitable candidates to determine if they were also depleted in Be. The Li survey was conducted on th ...
... we made a survey of bright F and G dwarfs that had not been studied for Li. One objective of that survey was to search for stars with depleted but detectable Li. Then Be observations would be made of suitable candidates to determine if they were also depleted in Be. The Li survey was conducted on th ...
Neutron stars: compact objects with relativistic
... Chandrasekhar limit in Newtonian gravity, which is attained asymptotically for ultra-relativistic fermions. For white dwarfs the general relativistic critical mass is very close to the Chandrasekhar limit. For neutron stars the maximum mass–so called Oppenheimer-Volkoff limit–is significantly smaller ...
... Chandrasekhar limit in Newtonian gravity, which is attained asymptotically for ultra-relativistic fermions. For white dwarfs the general relativistic critical mass is very close to the Chandrasekhar limit. For neutron stars the maximum mass–so called Oppenheimer-Volkoff limit–is significantly smaller ...
Convection in stellar envelopes: a changing paradigm
... these threads. The fluid in between is passive, it has zero temperature fluctuation and is neutrally buoyant. It flows towards the boundaries to replace the mass flowing in the threads, rather than being driven there by convective buoyancy. Convection in a cell at high Ra is therefore as non-local a ...
... these threads. The fluid in between is passive, it has zero temperature fluctuation and is neutrally buoyant. It flows towards the boundaries to replace the mass flowing in the threads, rather than being driven there by convective buoyancy. Convection in a cell at high Ra is therefore as non-local a ...
On the anomalous mass defect of strange stars in the Field
... advances have been made to derive an EOS, including perturbative and/or nonperturbative effects of confinement, to describe quark matter at all finite densities and temperatures. Recently, Yu. A. Simonov derived, from the first principles, the nonperturbative equation of state (NPEOS) of the quark-g ...
... advances have been made to derive an EOS, including perturbative and/or nonperturbative effects of confinement, to describe quark matter at all finite densities and temperatures. Recently, Yu. A. Simonov derived, from the first principles, the nonperturbative equation of state (NPEOS) of the quark-g ...
A Test of Pre-Main-Sequence Lithium Depletion Models
... Studies of open clusters have shown that lithium depletion is a strong function of both age and stellar mass (e.g. Soderblom et al. 1993b; Barrado y Navascués et al. 2004; Mentuch et al. 2008). These studies clearly show that the presence of a strong Li I line at 6707.8Å is an indicator of youth i ...
... Studies of open clusters have shown that lithium depletion is a strong function of both age and stellar mass (e.g. Soderblom et al. 1993b; Barrado y Navascués et al. 2004; Mentuch et al. 2008). These studies clearly show that the presence of a strong Li I line at 6707.8Å is an indicator of youth i ...
Models of rapidly rotating neutron stars: remnants of accretion
... ðm ¼ 2Þ. However, no instability is observed for the other two models during their simulated time interval of tens of milliseconds, suggesting that they are dynamically stable. Their analysis does not rule out the possibility that these models have non-axisymmetric secular instabilities, because the ...
... ðm ¼ 2Þ. However, no instability is observed for the other two models during their simulated time interval of tens of milliseconds, suggesting that they are dynamically stable. Their analysis does not rule out the possibility that these models have non-axisymmetric secular instabilities, because the ...