X-ray binaries
... dynamically important close to the stellar surface and determines the properties of the accretion flow. The radius at which the effects of the magnetic field dominate all others is called the Alfven radius. • For thin-disk accretion onto a neutron star, the Alfven radius is defined as the radius at whic ...
... dynamically important close to the stellar surface and determines the properties of the accretion flow. The radius at which the effects of the magnetic field dominate all others is called the Alfven radius. • For thin-disk accretion onto a neutron star, the Alfven radius is defined as the radius at whic ...
radial metallicity gradients and age-metallicity relation of stars in the
... solar neighbourhood. The survey selection box was defined using the 2MASS photometry: 12 < J < 14 and 0.23 < J − K < 0.45 +0.5E(B−V); if there were not enough targets, the red edge was extended2. With these criteria, we are predominantly selecting FG stars with magnitudes down to V = 16.5 (Gilmore e ...
... solar neighbourhood. The survey selection box was defined using the 2MASS photometry: 12 < J < 14 and 0.23 < J − K < 0.45 +0.5E(B−V); if there were not enough targets, the red edge was extended2. With these criteria, we are predominantly selecting FG stars with magnitudes down to V = 16.5 (Gilmore e ...
Discovery of an unusual bright eclipsing binary with the longest
... Fig. 5. Spectral energy distributions of the “hot component” (open circles) and a standard B6V star (thick line). Fig. 3. MASTER OT J095310.04+335352.8 spectrum obtained after eclipse on 2015-03-19. One can see the red part of an after eclipse spectrum. We note that Hα and NaI doublet are in absorpt ...
... Fig. 5. Spectral energy distributions of the “hot component” (open circles) and a standard B6V star (thick line). Fig. 3. MASTER OT J095310.04+335352.8 spectrum obtained after eclipse on 2015-03-19. One can see the red part of an after eclipse spectrum. We note that Hα and NaI doublet are in absorpt ...
The 13C(α,n)16O reaction rate. Recent estimates, new
... osynthesis in low mass stars. The above mentioned reaction is important because it is considered as the dominant neutron source active in stars with a mass included in the range 0.8 - 3 M⊙ , which actively contribute to the nucleosynthesis of heavy nuclei through neutron capture processes. Roughly ...
... osynthesis in low mass stars. The above mentioned reaction is important because it is considered as the dominant neutron source active in stars with a mass included in the range 0.8 - 3 M⊙ , which actively contribute to the nucleosynthesis of heavy nuclei through neutron capture processes. Roughly ...
Pre-main sequence stars, emission stars and recent star formation in
... formation event. Though the above fact is known, what is not known is that when this star formation process started and how it proceeded in the region. Thus the aim of the paper is to understand the star formation timescale in this complex, using the recently formed young open clusters. Though one a ...
... formation event. Though the above fact is known, what is not known is that when this star formation process started and how it proceeded in the region. Thus the aim of the paper is to understand the star formation timescale in this complex, using the recently formed young open clusters. Though one a ...
The fundamental parameters of the roAp star γ Equulei
... Context. A precise comparison of the predicted and observed locations of stars in the H-R diagram is needed when testing stellar interior theoretical models. For doing this, one must rely on accurate, observed stellar fundamental parameters (mass, radius, luminosity, and abundances). Aims. We determ ...
... Context. A precise comparison of the predicted and observed locations of stars in the H-R diagram is needed when testing stellar interior theoretical models. For doing this, one must rely on accurate, observed stellar fundamental parameters (mass, radius, luminosity, and abundances). Aims. We determ ...
Evolution and fate of very massive stars
... very massive stars, we calculated a new grid of models for such objects, for solar, LMC and SMC metallicities, which covers the initial mass range from 120 to 500 M . Both rotating and non-rotating models were calculated using the Geneva stellar evolution code and evolved until at least the end of ...
... very massive stars, we calculated a new grid of models for such objects, for solar, LMC and SMC metallicities, which covers the initial mass range from 120 to 500 M . Both rotating and non-rotating models were calculated using the Geneva stellar evolution code and evolved until at least the end of ...
Chapter 2 Basic Assumptions, Theorems, and Polytropes
... Since these theorems apply for any gas sphere in hydrostatic equilibrium where the ideal-gas law applies, we can use them for establishing the range of values to be expected in stars in general. In addition, it is possible to use the other half of the inequality to place upper limits on the values o ...
... Since these theorems apply for any gas sphere in hydrostatic equilibrium where the ideal-gas law applies, we can use them for establishing the range of values to be expected in stars in general. In addition, it is possible to use the other half of the inequality to place upper limits on the values o ...
Dai, S - PulsarAstronomy.net
... Neutron Stars through Astrometric Microlensing Sahu, K. C.; Albrow, M.; Anderson, J.; Bond, H. E.; Bond, I.; Brown, T. M.; Casertano, S.; Dominik, M.; Ferguson, H. C.; Fryer, C.; Livio, M.; Mao, S.; Perrott, Y.; Udalski, A.; Yock, P. 2012, American Astronomical Society Meeting Abstracts, 220, #307.0 ...
... Neutron Stars through Astrometric Microlensing Sahu, K. C.; Albrow, M.; Anderson, J.; Bond, H. E.; Bond, I.; Brown, T. M.; Casertano, S.; Dominik, M.; Ferguson, H. C.; Fryer, C.; Livio, M.; Mao, S.; Perrott, Y.; Udalski, A.; Yock, P. 2012, American Astronomical Society Meeting Abstracts, 220, #307.0 ...
fundamental properties of kepler planet- candidate
... (Vandakurov 1968; Tassoul 1980; Gough 1986). The large frequency separation Δν is the spacing between modes with the same spherical degree l and consecutive radial order n, and probes the sound travel time across the stellar diameter. This means that Δν is related to the mean stellar density and is ...
... (Vandakurov 1968; Tassoul 1980; Gough 1986). The large frequency separation Δν is the spacing between modes with the same spherical degree l and consecutive radial order n, and probes the sound travel time across the stellar diameter. This means that Δν is related to the mean stellar density and is ...
on the mass of the black hole in gs
... coefficient of 0.08 (Lucy 1967), appropriate for an early to mid-K secondary (FMB). Simulations show that the use of Kurucz stellar atmospheres instead of a blackbody approximation changes the amplitude of the ellipsoidal variation by 1%–2% at most, an effect much smaller than the uncertainty in the ...
... coefficient of 0.08 (Lucy 1967), appropriate for an early to mid-K secondary (FMB). Simulations show that the use of Kurucz stellar atmospheres instead of a blackbody approximation changes the amplitude of the ellipsoidal variation by 1%–2% at most, an effect much smaller than the uncertainty in the ...
Galaxies on Sub-Galactic Scales
... dwarf galaxy properties, providing first evidence for a possible lower mass limit for dark matter halos in visible galaxies, and reopening the discussion about the building block scenario for the Milky Way halo. Nonetheless, these results are still drawn only from a relatively small number of galaxi ...
... dwarf galaxy properties, providing first evidence for a possible lower mass limit for dark matter halos in visible galaxies, and reopening the discussion about the building block scenario for the Milky Way halo. Nonetheless, these results are still drawn only from a relatively small number of galaxi ...
Circum-stellar medium around rotating massive stars at solar
... We use as input the most recent grid of rotating stellar models provided by the Geneva group (Ekström et al. 2012). We only consider the following massive star models (see Table 1): 15, 20, 25, 32, 40, 60, 85, and 120 M . Models of lower mass stars have radiative winds that are too weak to be of in ...
... We use as input the most recent grid of rotating stellar models provided by the Geneva group (Ekström et al. 2012). We only consider the following massive star models (see Table 1): 15, 20, 25, 32, 40, 60, 85, and 120 M . Models of lower mass stars have radiative winds that are too weak to be of in ...
constraints on grain formation around carbon stars
... We report the results of an investigation into the physical conditions in the mass outflows of asymptotic giant branch (AGB) carbon stars that are required for the formation of micron-sized presolar graphite grains, with and without previously formed internal crystals of titanium carbide ( TiC ). A ...
... We report the results of an investigation into the physical conditions in the mass outflows of asymptotic giant branch (AGB) carbon stars that are required for the formation of micron-sized presolar graphite grains, with and without previously formed internal crystals of titanium carbide ( TiC ). A ...
PDF only - at www.arxiv.org.
... 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 to have an irregular morphology with two dense cores. Contrary to the claims by S ...
... 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 to have an irregular morphology with two dense cores. Contrary to the claims by S ...
Determination of the distance to the Andromeda Galaxy using variable stars U
... where b and v are the instrumental magnitudes, B and V the standard magnitudes, and Ai are the transformation coefficients. The resulting mean standard deviation of the fits is 0.02 mag. The transformation coefficients cannot be directly applied to the M 31 instrumental magnitudes because the latter are ...
... where b and v are the instrumental magnitudes, B and V the standard magnitudes, and Ai are the transformation coefficients. The resulting mean standard deviation of the fits is 0.02 mag. The transformation coefficients cannot be directly applied to the M 31 instrumental magnitudes because the latter are ...
Absolute Magnitudes of Turnoff Stars in Globular Clusters Palomar
... 0 to -1) is an increase in brightness by a factor of 2.5. The apparent magnitude measures the brightness that a star appears to us on Earth. Absolute magnitude is a measure of how bright the star would be if it was viewed from 32.6 lightyears (10 parsecs) away. Another stellar characteristic, color, ...
... 0 to -1) is an increase in brightness by a factor of 2.5. The apparent magnitude measures the brightness that a star appears to us on Earth. Absolute magnitude is a measure of how bright the star would be if it was viewed from 32.6 lightyears (10 parsecs) away. Another stellar characteristic, color, ...
CH15.AST1001.S15.EDS
... Why do orbits of bulge stars bob up and down? A. They're stuck to the interstellar medium. B. The gravity of disk stars pulls them toward the disk. C. Halo stars knock them back into the disk. ...
... Why do orbits of bulge stars bob up and down? A. They're stuck to the interstellar medium. B. The gravity of disk stars pulls them toward the disk. C. Halo stars knock them back into the disk. ...
Transiting exoplanets from the CoRoT space mission
... The target star CoRoT-24 was observed on the detector E1 of the CoRoT satellite during its second Long Run pointing at the direction opposite to the approximate galactic center (“anticenter” in the CoRoT jargon). The observations lasted from 16 Nov. 2008 until 8 March 2009, covering a total span of ...
... The target star CoRoT-24 was observed on the detector E1 of the CoRoT satellite during its second Long Run pointing at the direction opposite to the approximate galactic center (“anticenter” in the CoRoT jargon). The observations lasted from 16 Nov. 2008 until 8 March 2009, covering a total span of ...
A CCD Search for Variable Stars of Spectral Type B in the Northern
... in B, 25 in U, and 24 in V, Hill (1967) found the star to be variable, derived a period of 0.39912 d (frequency 2.5055 d 1 ) and the amplitudes (half ranges) of 9 mmag and 8 mmag in B and U, respectively (no V amplitude was given). On the strength of these results, Hill (1967) classified the star as ...
... in B, 25 in U, and 24 in V, Hill (1967) found the star to be variable, derived a period of 0.39912 d (frequency 2.5055 d 1 ) and the amplitudes (half ranges) of 9 mmag and 8 mmag in B and U, respectively (no V amplitude was given). On the strength of these results, Hill (1967) classified the star as ...
Formation and Evolution of Binary Millisecond Pulsars with Helium
... with its spun-up NS companion. Since the properties of red giants are dictated primarily by their core masses, mc , and not by the mass of the stars themselves or by the mass-transfer rate, Ṁ2 , it is possible to calculate a semi-analytic relationship between the final orbital periods of BMSPs and ...
... with its spun-up NS companion. Since the properties of red giants are dictated primarily by their core masses, mc , and not by the mass of the stars themselves or by the mass-transfer rate, Ṁ2 , it is possible to calculate a semi-analytic relationship between the final orbital periods of BMSPs and ...
Constellations
... sets. Use them to locate Polaris, also known as the North Star. The Big Dipper and Cassiopeia are always opposite each other and rotate counterclockwise around Polaris, with Polaris in the center. ...
... sets. Use them to locate Polaris, also known as the North Star. The Big Dipper and Cassiopeia are always opposite each other and rotate counterclockwise around Polaris, with Polaris in the center. ...
Transiting planets from WASP
... October 2013. For all spectroscopic observations, radial velocities (RVs) were computed using the weighted cross-correlation technique described in Pepe et al. (2002). These RVs are presented in Tables 1–3. For each star, RV variations were detected with periods similar to those found in the WASP ph ...
... October 2013. For all spectroscopic observations, radial velocities (RVs) were computed using the weighted cross-correlation technique described in Pepe et al. (2002). These RVs are presented in Tables 1–3. For each star, RV variations were detected with periods similar to those found in the WASP ph ...
Star Formation and Feedback II: The IMF and the SFR
... from other sources of ionization). The global SFR we measure is very comparable to the present SFR obtained from the photometric analysis of the resolved stellar populations by Harris & Zaritsky (2004), and only slightly lower than the SFRSMC ∼ 0.05 M" yr−1 obtained by Wilke et al. (2004) based on t ...
... from other sources of ionization). The global SFR we measure is very comparable to the present SFR obtained from the photometric analysis of the resolved stellar populations by Harris & Zaritsky (2004), and only slightly lower than the SFRSMC ∼ 0.05 M" yr−1 obtained by Wilke et al. (2004) based on t ...
Lesson Plan - ScienceA2Z.com
... the surrounding disk because of the young, hot OB stars that inhabit them. (OB stars:Hot, massive, short lived stars) 4. Roughly half of all spirals are observed to have an additional component in the form of a bar-like structure, extending from the central bulge (can be seen in the above picture, a ...
... the surrounding disk because of the young, hot OB stars that inhabit them. (OB stars:Hot, massive, short lived stars) 4. Roughly half of all spirals are observed to have an additional component in the form of a bar-like structure, extending from the central bulge (can be seen in the above picture, a ...
Main sequence
In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell. Stars on this band are known as main-sequence stars or ""dwarf"" stars.After a star has formed, it generates thermal energy in the dense core region through the nuclear fusion of hydrogen atoms into helium. During this stage of the star's lifetime, it is located along the main sequence at a position determined primarily by its mass, but also based upon its chemical composition and other factors. All main-sequence stars are in hydrostatic equilibrium, where outward thermal pressure from the hot core is balanced by the inward pressure of gravitational collapse from the overlying layers. The strong dependence of the rate of energy generation in the core on the temperature and pressure helps to sustain this balance. Energy generated at the core makes its way to the surface and is radiated away at the photosphere. The energy is carried by either radiation or convection, with the latter occurring in regions with steeper temperature gradients, higher opacity or both.The main sequence is sometimes divided into upper and lower parts, based on the dominant process that a star uses to generate energy. Stars below about 1.5 times the mass of the Sun (or 1.5 solar masses (M☉)) primarily fuse hydrogen atoms together in a series of stages to form helium, a sequence called the proton–proton chain. Above this mass, in the upper main sequence, the nuclear fusion process mainly uses atoms of carbon, nitrogen and oxygen as intermediaries in the CNO cycle that produces helium from hydrogen atoms. Main-sequence stars with more than two solar masses undergo convection in their core regions, which acts to stir up the newly created helium and maintain the proportion of fuel needed for fusion to occur. Below this mass, stars have cores that are entirely radiative with convective zones near the surface. With decreasing stellar mass, the proportion of the star forming a convective envelope steadily increases, whereas main-sequence stars below 0.4 M☉ undergo convection throughout their mass. When core convection does not occur, a helium-rich core develops surrounded by an outer layer of hydrogen.In general, the more massive a star is, the shorter its lifespan on the main sequence. After the hydrogen fuel at the core has been consumed, the star evolves away from the main sequence on the HR diagram. The behavior of a star now depends on its mass, with stars below 0.23 M☉ becoming white dwarfs directly, whereas stars with up to ten solar masses pass through a red giant stage. More massive stars can explode as a supernova, or collapse directly into a black hole.