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The chemical composition of IK Pegasi
... inferred from the calcium Hand K lines (Titus & Morgan 1940; Roman, Morgan & Eggen 1948). The hydrogen-line spectral type is intermediate between the two. This defines the classical Am stars. A marginal Am star is one in which the metallic and calcium types differ by less than five subtypes. These d ...
... inferred from the calcium Hand K lines (Titus & Morgan 1940; Roman, Morgan & Eggen 1948). The hydrogen-line spectral type is intermediate between the two. This defines the classical Am stars. A marginal Am star is one in which the metallic and calcium types differ by less than five subtypes. These d ...
BD−21 3873: another yellow-symbiotic barium star
... that respect, this star appears to be a twin of AG Dra, another yellow symbiotic system analyzed in a previous paper (Smith et al., 1996). The heavy-element abundance distributions of AG Dra and BD−21◦ 3873 are almost identical, and are best reproduced by a s-process with a neutron exposure paramete ...
... that respect, this star appears to be a twin of AG Dra, another yellow symbiotic system analyzed in a previous paper (Smith et al., 1996). The heavy-element abundance distributions of AG Dra and BD−21◦ 3873 are almost identical, and are best reproduced by a s-process with a neutron exposure paramete ...
Anisotropy of the Hectometer Cosmic Radio Background
... a 0.1 degree and the spacecraft rotation period. By way of illustration, Fig. 1 shows oscillograms of the signals from the S-antenna output in the December 27, 1997 session. When RAD1 is switched from the standard mode (the beginning and end of the records correspond to this mode) to the mode of sca ...
... a 0.1 degree and the spacecraft rotation period. By way of illustration, Fig. 1 shows oscillograms of the signals from the S-antenna output in the December 27, 1997 session. When RAD1 is switched from the standard mode (the beginning and end of the records correspond to this mode) to the mode of sca ...
Star Formation and Young Clusters in Cygnus
... plane between longitudes 67◦ and 100◦ . The Great Cygnus Rift is most prominent to the right, and the 10 degree large Cygnus X region provides the highest extinction in the whole field. The North America nebula is indicated. At higher longitudes one finds the large cloud Kh 141 = TGU 541 associated ...
... plane between longitudes 67◦ and 100◦ . The Great Cygnus Rift is most prominent to the right, and the 10 degree large Cygnus X region provides the highest extinction in the whole field. The North America nebula is indicated. At higher longitudes one finds the large cloud Kh 141 = TGU 541 associated ...
POLYTROPES - Princeton
... possible to show that all polytropes with n > 5 have infinite radii. This means that only solutions with n < 5 have a surface. The two cases most interesting for real stars have n = 1.5 and n = 3, and unfortunately these do not have analytic solutions. A solution of eq. (poly.6) depends on one param ...
... possible to show that all polytropes with n > 5 have infinite radii. This means that only solutions with n < 5 have a surface. The two cases most interesting for real stars have n = 1.5 and n = 3, and unfortunately these do not have analytic solutions. A solution of eq. (poly.6) depends on one param ...
Fundamentals of Stellar Evolution Theory: Understanding the HRD
... 2.1. Low-, Intermediate-, and High-Mass Stars: definition By low mass stars we define those which shortly after leaving the main sequence toward the red giant branch (RGB), develop an electron degenerate core composed of helium. When the mass (MHe ) of the He core has grown to a critical value (0.45 ...
... 2.1. Low-, Intermediate-, and High-Mass Stars: definition By low mass stars we define those which shortly after leaving the main sequence toward the red giant branch (RGB), develop an electron degenerate core composed of helium. When the mass (MHe ) of the He core has grown to a critical value (0.45 ...
A Second Shell in the Fornax dSph Galaxy
... We have collected photometry in V and I bands for an area of 3.1 × 3.1 deg2 centred on the Fornax dSph using the Wide-Field Imager attached to the SSO 1-m telescope. The region was imaged using a mosaic of 4 × 4 fields (labelled F1–F16), and the data are complete to a magnitude of V = 20 at the colo ...
... We have collected photometry in V and I bands for an area of 3.1 × 3.1 deg2 centred on the Fornax dSph using the Wide-Field Imager attached to the SSO 1-m telescope. The region was imaged using a mosaic of 4 × 4 fields (labelled F1–F16), and the data are complete to a magnitude of V = 20 at the colo ...
Chemical abundances of metal-poor RR Lyrae stars in the Magellanic Clouds
... We present for the first time a detailed spectroscopic study of chemical element abundances of metalpoor RR Lyrae stars in the Large and Small Magellanic Cloud (LMC and SMC). Using the MagE echelle spectrograph at the 6.5 m Magellan telescopes, we obtain medium resolution (R ∼ 2000−6000) spectra of ...
... We present for the first time a detailed spectroscopic study of chemical element abundances of metalpoor RR Lyrae stars in the Large and Small Magellanic Cloud (LMC and SMC). Using the MagE echelle spectrograph at the 6.5 m Magellan telescopes, we obtain medium resolution (R ∼ 2000−6000) spectra of ...
Chemical Composition of Selected Metal Poor Stars
... the galactic disk, galactic halo has a smaller density of gas (interstellar matter) which may be due to the collapse of the Galaxy (Eggen et al. 1962). Therefore less stars are formed per unit volume, so that the metal enrichment of the halo is much smaller than that of the disk. This collapse can a ...
... the galactic disk, galactic halo has a smaller density of gas (interstellar matter) which may be due to the collapse of the Galaxy (Eggen et al. 1962). Therefore less stars are formed per unit volume, so that the metal enrichment of the halo is much smaller than that of the disk. This collapse can a ...
The Herschel Orion Protostar Survey: Luminosity and Envelope
... SEDs best fit with envelopes that are generally less massive than those of Class 0 and Class I protostars. With model fits, Furlan et al. (2016) found a systematic decrease in envelope density from Class 0 to Class I to flatspectrum protostars, with an overall decrease of a factor of 50. This decrea ...
... SEDs best fit with envelopes that are generally less massive than those of Class 0 and Class I protostars. With model fits, Furlan et al. (2016) found a systematic decrease in envelope density from Class 0 to Class I to flatspectrum protostars, with an overall decrease of a factor of 50. This decrea ...
Formation of millisecond pulsars with CO white dwarf companions–I
... Donor stars in systems with wide orbits (Porb 102 –103 d) prior to the mass-transfer phase develop a deep convective envelope as they become giant stars before filling their Roche lobes. The response to mass-loss for these stars with outer layers of constant low entropy and negative adiabatic mass ...
... Donor stars in systems with wide orbits (Porb 102 –103 d) prior to the mass-transfer phase develop a deep convective envelope as they become giant stars before filling their Roche lobes. The response to mass-loss for these stars with outer layers of constant low entropy and negative adiabatic mass ...
The X-ray emission from shock cooling zones in O star winds
... single temperature of log T [K] ≈ 6.60 (see their Fig. 2). But the flux deficiency in the calculated spectrum for energies below 0.45 keV indicated that a cooler shock component of log T ≈ 6.30 and of roughly equal filling factor as the hotter component should be present (Fig. 4 of Hillier et al., a ...
... single temperature of log T [K] ≈ 6.60 (see their Fig. 2). But the flux deficiency in the calculated spectrum for energies below 0.45 keV indicated that a cooler shock component of log T ≈ 6.30 and of roughly equal filling factor as the hotter component should be present (Fig. 4 of Hillier et al., a ...
mass and temperature of the twa 7 debris disk
... Two models that are able to fit the observed emission spectrum are shown in Figure 2. In both models the dust has a range of temperatures; however, there are two different physical motivations behind the origin of this range. In model 3 (dotted line of Fig. 2), the dust is assumed to all lie at the ...
... Two models that are able to fit the observed emission spectrum are shown in Figure 2. In both models the dust has a range of temperatures; however, there are two different physical motivations behind the origin of this range. In model 3 (dotted line of Fig. 2), the dust is assumed to all lie at the ...
Chapter 7 Elliptical Galaxies Chapter 16 Elliptical Galaxies
... spectra overlap and it is not possible to derive the kinematics from the analysis of single absorption lines. Therefore, more sophisticated methods are needed. For example, the velocity v and the projected velocity dispersion σ can be measured by comparison of the galaxy spectrum with a suitably bro ...
... spectra overlap and it is not possible to derive the kinematics from the analysis of single absorption lines. Therefore, more sophisticated methods are needed. For example, the velocity v and the projected velocity dispersion σ can be measured by comparison of the galaxy spectrum with a suitably bro ...
A Rotational and Variability Study of a Large Sample of... in NGC 2264 M. H. Lamm , C. A. L. Bailer-Jones
... Nebular cluster (ONC). They found that the period distribution for higher mass stars (i. e. M ≥ 0.25M ) is bimodal with peaks at 2 and 8 days. The bimodality is interpreted as an effect of disk-star interactions in PMS stars: Slow rotators have been magnetically locked to their disks which prevent ...
... Nebular cluster (ONC). They found that the period distribution for higher mass stars (i. e. M ≥ 0.25M ) is bimodal with peaks at 2 and 8 days. The bimodality is interpreted as an effect of disk-star interactions in PMS stars: Slow rotators have been magnetically locked to their disks which prevent ...
Stellar contents and star formation in the young open cluster Stock 8
... may not play any significant role in the star formation process. However, the influence of star formation history of young clusters on the form of IMF is still an open issue. High-mass stars have strong influence on their surroundings and can significantly affect the formation of low-mass stars. Rec ...
... may not play any significant role in the star formation process. However, the influence of star formation history of young clusters on the form of IMF is still an open issue. High-mass stars have strong influence on their surroundings and can significantly affect the formation of low-mass stars. Rec ...
molecular cloud evolution. ii. from cloud formation to the
... simulations show that (1) The clouds are not in a state of equilibrium. Instead, they undergo secular evolution. During its early stages, the cloud’s mass and gravitational energy jEg j increase steadily, while the turbulent energy Ek reaches a plateau. (2) When jEg j becomes comparable to Ek , glob ...
... simulations show that (1) The clouds are not in a state of equilibrium. Instead, they undergo secular evolution. During its early stages, the cloud’s mass and gravitational energy jEg j increase steadily, while the turbulent energy Ek reaches a plateau. (2) When jEg j becomes comparable to Ek , glob ...
Applications of Photospheric Spot Temperature Models ... Stellar Angular Momentum Evolution
... Those studies detecting a bimodal rotation period distribution find that stars with disks tend to distribute around one rotation period, while stars without disks tend to distribute around another rotation period. For those studies reporting a bimodal distribution, the favored period modes are two ...
... Those studies detecting a bimodal rotation period distribution find that stars with disks tend to distribute around one rotation period, while stars without disks tend to distribute around another rotation period. For those studies reporting a bimodal distribution, the favored period modes are two ...
The stellar populations in the low-luminosity, early
... many luminous ETGs that have been the subject of stellar population analysis. Therefore, results for LLEs may be more susceptible to the well-known age–metallicity degeneracies that plague such analysis. It is for this reason that we wished to check our results for the most extreme LLEs, using new d ...
... many luminous ETGs that have been the subject of stellar population analysis. Therefore, results for LLEs may be more susceptible to the well-known age–metallicity degeneracies that plague such analysis. It is for this reason that we wished to check our results for the most extreme LLEs, using new d ...
Evolution and colors of helium-core white dwarf stars with high
... The study of the evolution of low-mass He white dwarfs has captured the attention of researchers since Kippenhahn et al. (1967) suggested that these stars could be the natural result of substantial mass loss from low-mass red giant stars filling their Roche lobes in binary systems. Later, Webbink (1 ...
... The study of the evolution of low-mass He white dwarfs has captured the attention of researchers since Kippenhahn et al. (1967) suggested that these stars could be the natural result of substantial mass loss from low-mass red giant stars filling their Roche lobes in binary systems. Later, Webbink (1 ...
Star Formation and Dynamics in the Galactic Centre
... The first attempts to estimate the mass enclosed in the central parsec are radial velocity measurements of ionized gas located in the structure which is known as minispiral (Lacy et al. 1980). On the other hand, the radial velocity of ionized gas may be affected by a plethora of processes besides gr ...
... The first attempts to estimate the mass enclosed in the central parsec are radial velocity measurements of ionized gas located in the structure which is known as minispiral (Lacy et al. 1980). On the other hand, the radial velocity of ionized gas may be affected by a plethora of processes besides gr ...
Multi-dimensional structure of accreting young stars
... T eff (see e.g. Chabrier & Baraffe 1997). The small scale surface convection resulting from the rapidly decreasing pressure scale height near the surface of a star as well as steep surface radial gradients require a smaller radial spacing near the surface. We thus design the radial grid for the 2D s ...
... T eff (see e.g. Chabrier & Baraffe 1997). The small scale surface convection resulting from the rapidly decreasing pressure scale height near the surface of a star as well as steep surface radial gradients require a smaller radial spacing near the surface. We thus design the radial grid for the 2D s ...
Introduction astronomy
... Gustav Kirchhoff & Robert Bunsen (1860/1861) Chemische Analyse durch Spectralbeobachtungen “In a memoir published by one of us (Kirchhoff 1859), it was proved from theoretical considerations that the spectrum of an incandescent gas becomes reversed (that is, the bright lines become changed into dark ...
... Gustav Kirchhoff & Robert Bunsen (1860/1861) Chemische Analyse durch Spectralbeobachtungen “In a memoir published by one of us (Kirchhoff 1859), it was proved from theoretical considerations that the spectrum of an incandescent gas becomes reversed (that is, the bright lines become changed into dark ...
Molecular cloud regulated star formation in galaxies
... In response to these problems with the simplest star formation and feedback criteria several authors have introduced ‘multiphase’ models for star formation in which the ISM is treated as a number of distinct phases. These schemes take various forms including modification of the simulation algorithm ...
... In response to these problems with the simplest star formation and feedback criteria several authors have introduced ‘multiphase’ models for star formation in which the ISM is treated as a number of distinct phases. These schemes take various forms including modification of the simulation algorithm ...
SN 2011dh and the progenitors of Type IIb supernovae Mattias Ergon
... nearby galaxy M51, and images covering the location where supernova (SN) 2011dh would later occur are obtained. Examining the position of the SN reveals an anonymous yellow star, seemingly similar to millions of other stars in this galaxy. However, beneath the surface, in the interior of the star, t ...
... nearby galaxy M51, and images covering the location where supernova (SN) 2011dh would later occur are obtained. Examining the position of the SN reveals an anonymous yellow star, seemingly similar to millions of other stars in this galaxy. However, beneath the surface, in the interior of the star, t ...