Variable stars in the globular cluster M 92
... Kadla et al. (1983). They also give the cross-identification of variable stars in the third catalogue of Sawyer-Hogg (1973) with numbering system of Nassau (1938). It appears now that v12 is Nassau’s star no. 10 and v15 corresponds to Nassau’s star no. 12. Oosterhoff (1944) rediscussed the observati ...
... Kadla et al. (1983). They also give the cross-identification of variable stars in the third catalogue of Sawyer-Hogg (1973) with numbering system of Nassau (1938). It appears now that v12 is Nassau’s star no. 10 and v15 corresponds to Nassau’s star no. 12. Oosterhoff (1944) rediscussed the observati ...
Future Supernova Projects
... • small dispersion • single objects (simpler than galaxies) • can be observed over wide z range Challenges: • dust (grey dust) • chemical composition • evolution • photometric calibration (e.g., Vega) • environmental differences Systematics • lensing Step 2 ...
... • small dispersion • single objects (simpler than galaxies) • can be observed over wide z range Challenges: • dust (grey dust) • chemical composition • evolution • photometric calibration (e.g., Vega) • environmental differences Systematics • lensing Step 2 ...
UCAC4 is a compiled, all-sky star catalog covering mainly the 8 to
... value: the one given in the catalog for sigma position. If the astrometric data for a star was substituted from an external catalog like Hipparcos, Tycho or High proper motion data, a mean error in position and proper motion depending on the catalog and magnitude of the star was adopted. For stars w ...
... value: the one given in the catalog for sigma position. If the astrometric data for a star was substituted from an external catalog like Hipparcos, Tycho or High proper motion data, a mean error in position and proper motion depending on the catalog and magnitude of the star was adopted. For stars w ...
Data Reduction pipeline for MOST Guide Stars and Application to
... A further issue is that if the stray light is extremely high or if the targets have been observed only during orbital phases of maximum stray light (for example switch targets), the decorrelation method significantly increases the time domain point-to-point scatter. For those targets, the decorrelati ...
... A further issue is that if the stray light is extremely high or if the targets have been observed only during orbital phases of maximum stray light (for example switch targets), the decorrelation method significantly increases the time domain point-to-point scatter. For those targets, the decorrelati ...
EXPLORING STELLAR EVOLUTION MODELS OF sdB STARS
... classes of stars. Recent detections of g-mode pulsations in evolved He burning stars allow a rare comparison of their internal structure with stellar models. Asteroseismology of subdwarf B (sdB) stars suggests convective cores of 0.22–0.28 Me, 45% of the total stellar mass. Previous studies found s ...
... classes of stars. Recent detections of g-mode pulsations in evolved He burning stars allow a rare comparison of their internal structure with stellar models. Asteroseismology of subdwarf B (sdB) stars suggests convective cores of 0.22–0.28 Me, 45% of the total stellar mass. Previous studies found s ...
Present classification: Suggested
... about 7 percent. In my opinion, first, this level is too high, and second, the authors underestimate it. Odessa, August 7–11, 2007 ...
... about 7 percent. In my opinion, first, this level is too high, and second, the authors underestimate it. Odessa, August 7–11, 2007 ...
The eccentricities of the barium stars
... We investigate the eccentricities of barium (Ba ii) stars formed via a stellar wind accretion model. We carry out a series of Monte Carlo simulations using a rapid binary evolution algorithm, which incorporates full tidal evolution, mass loss and accretion, and nucleosynthesis and dredge-up on the t ...
... We investigate the eccentricities of barium (Ba ii) stars formed via a stellar wind accretion model. We carry out a series of Monte Carlo simulations using a rapid binary evolution algorithm, which incorporates full tidal evolution, mass loss and accretion, and nucleosynthesis and dredge-up on the t ...
Properties of Wolf-Rayet Stars - Paul Crowther, University of Sheffield
... WR stars can readily be obtained (e.g. Willis et al. 2004). Alternatively, optical and near-IR He i P Cygni profiles or mid-IR fine-structure metal lines may be used to derive reliable wind velocities (Howarth & Schmutz 1992; Dessart et al. 2000), for which the radial dependence is assumed to follow ...
... WR stars can readily be obtained (e.g. Willis et al. 2004). Alternatively, optical and near-IR He i P Cygni profiles or mid-IR fine-structure metal lines may be used to derive reliable wind velocities (Howarth & Schmutz 1992; Dessart et al. 2000), for which the radial dependence is assumed to follow ...
WASP-120b, WASP-122b and WASP-123b: Three newly discovered
... (2007a). Details of observations for each star in this paper can be found in Table 1. The phase-folded WASP data are displayed in the top panels of Figs. 1, 2 and 3. We used the method of Maxted et al. (2011) to search the WASP photometry for modulations caused by star spots. We detected no rotation ...
... (2007a). Details of observations for each star in this paper can be found in Table 1. The phase-folded WASP data are displayed in the top panels of Figs. 1, 2 and 3. We used the method of Maxted et al. (2011) to search the WASP photometry for modulations caused by star spots. We detected no rotation ...
The spectroscopic Hertzsprung
... stars that have a luminosity larger than the luminosity of a single star of comparable mass and evolutionary state. Kippenhahn & Weigert (1990) showed that main sequence stars are expected to obey the relation L ∼ M α µβ , where µ is the average mean molecular weight and β > 1. An overluminosity is ...
... stars that have a luminosity larger than the luminosity of a single star of comparable mass and evolutionary state. Kippenhahn & Weigert (1990) showed that main sequence stars are expected to obey the relation L ∼ M α µβ , where µ is the average mean molecular weight and β > 1. An overluminosity is ...
A COMPREHENSIVE COMPARISON OF THE SUN TO
... than 94% 2% of the stars in the Kroupa (2002) IMF. Fourteen brown dwarfs and nine white dwarfs within 7.1 pc were not included in this sample. Including them yields 94% — the same result obtained from the IMF. Our 95% 2% result should be compared with the 91% reported by Gonzalez (1999b). The Su ...
... than 94% 2% of the stars in the Kroupa (2002) IMF. Fourteen brown dwarfs and nine white dwarfs within 7.1 pc were not included in this sample. Including them yields 94% — the same result obtained from the IMF. Our 95% 2% result should be compared with the 91% reported by Gonzalez (1999b). The Su ...
Pulsars as Astrophysical Laboratories for Nuclear and Particle Physics
... potential energy of the matter accreted from a low-mass companion is the energy source, and (3) magnetars (e.g, SGR 1806-20), where the decay of a ultra-strong magnetic field powers the radiation. The fastest, very recently discovered neutron star, PSR J1748-2446ad, rotates at a period of 1.39 ms (w ...
... potential energy of the matter accreted from a low-mass companion is the energy source, and (3) magnetars (e.g, SGR 1806-20), where the decay of a ultra-strong magnetic field powers the radiation. The fastest, very recently discovered neutron star, PSR J1748-2446ad, rotates at a period of 1.39 ms (w ...
Chapter 5 - Leiden Observatory
... momentum loss, CE, magnetic braking, and gravitational radiation are taken into account with appropriate recipes at every timestep [Portegies Zwart & Verbunt, 1996; Portegies Zwart & Yungelson, 1998]. Following mass transfer in a binary, the donor may turn into a helium-burning star without hydrogen ...
... momentum loss, CE, magnetic braking, and gravitational radiation are taken into account with appropriate recipes at every timestep [Portegies Zwart & Verbunt, 1996; Portegies Zwart & Yungelson, 1998]. Following mass transfer in a binary, the donor may turn into a helium-burning star without hydrogen ...
A Second Luminous Blue Variable in the Quintuplet Cluster
... resolution only. Therefore, although we suspect that the value of He/H is not far from normal, we cannot rule out a much higher value. Finally, we consider the abundances of Mg, Si, and Fe. The striking similarity of the Mg ii lines in FMM#362 to those in the Pistol Star support a higher than solar ...
... resolution only. Therefore, although we suspect that the value of He/H is not far from normal, we cannot rule out a much higher value. Finally, we consider the abundances of Mg, Si, and Fe. The striking similarity of the Mg ii lines in FMM#362 to those in the Pistol Star support a higher than solar ...
L17 SHELL-SHOCKED DIFFUSION MODEL FOR THE LIGHT
... circumstellar envelope, created when ∼10 M, was ejected in the decade before the supernova in an eruption analogous to that of h Carinae. The supernova light is produced primarily by diffusion of thermal energy following the passage of the blast wave through this shell. This model differs from tradi ...
... circumstellar envelope, created when ∼10 M, was ejected in the decade before the supernova in an eruption analogous to that of h Carinae. The supernova light is produced primarily by diffusion of thermal energy following the passage of the blast wave through this shell. This model differs from tradi ...
Stellar evolution
Stellar evolution is the process by which a star changes during its lifetime. Depending on the mass of the star, this lifetime ranges from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the age of the universe. The table shows the lifetimes of stars as a function of their masses. All stars are born from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main-sequence star.Nuclear fusion powers a star for most of its life. Initially the energy is generated by the fusion of hydrogen atoms at the core of the main-sequence star. Later, as the preponderance of atoms at the core becomes helium, stars like the Sun begin to fuse hydrogen along a spherical shell surrounding the core. This process causes the star to gradually grow in size, passing through the subgiant stage until it reaches the red giant phase. Stars with at least half the mass of the Sun can also begin to generate energy through the fusion of helium at their core, whereas more-massive stars can fuse heavier elements along a series of concentric shells. Once a star like the Sun has exhausted its nuclear fuel, its core collapses into a dense white dwarf and the outer layers are expelled as a planetary nebula. Stars with around ten or more times the mass of the Sun can explode in a supernova as their inert iron cores collapse into an extremely dense neutron star or black hole. Although the universe is not old enough for any of the smallest red dwarfs to have reached the end of their lives, stellar models suggest they will slowly become brighter and hotter before running out of hydrogen fuel and becoming low-mass white dwarfs.Stellar evolution is not studied by observing the life of a single star, as most stellar changes occur too slowly to be detected, even over many centuries. Instead, astrophysicists come to understand how stars evolve by observing numerous stars at various points in their lifetime, and by simulating stellar structure using computer models.In June 2015, astronomers reported evidence for Population III stars in the Cosmos Redshift 7 galaxy at z = 6.60. Such stars are likely to have existed in the very early universe (i.e., at high redshift), and may have started the production of chemical elements heavier than hydrogen that are needed for the later formation of planets and life as we know it.