Betelgeuse: an unauthorized biography
... relation L = 4πσR2*Teff4 where L is the luminosity and R* is the stellar radius. In practice, several methods may be applied, including the “infrared flux” method. This relies on knowledge of the angular diameter α of the star and the flux F of its radiation at Earth. The distance to the star cancel ...
... relation L = 4πσR2*Teff4 where L is the luminosity and R* is the stellar radius. In practice, several methods may be applied, including the “infrared flux” method. This relies on knowledge of the angular diameter α of the star and the flux F of its radiation at Earth. The distance to the star cancel ...
Advanced information on the Nobel Prize in Physics 2002, 8 October
... The reliability of Davis’ results depends very much on the extraction efficiency of argon. This was very carefully studied. A known amount of 36Ar was introduced regularly and the extraction efficiency was determined to 95%. Radioactive 37Ar was produced in the tank and the extraction efficiency was ...
... The reliability of Davis’ results depends very much on the extraction efficiency of argon. This was very carefully studied. A known amount of 36Ar was introduced regularly and the extraction efficiency was determined to 95%. Radioactive 37Ar was produced in the tank and the extraction efficiency was ...
Photospheric activity, rotation, and star
... models show that the starspots have a remarkable differential rotation, which may contribute to an uncertainty of the stellar rotation period of ≈10 percent, i.e., of ±0.3 days, comparable with the above upper limit (cf. Sect. 5.2). The polar flattening of the star due to the centrifugal potential is ...
... models show that the starspots have a remarkable differential rotation, which may contribute to an uncertainty of the stellar rotation period of ≈10 percent, i.e., of ±0.3 days, comparable with the above upper limit (cf. Sect. 5.2). The polar flattening of the star due to the centrifugal potential is ...
PDF only - at www.arxiv.org.
... firmly established, and Mayer knew that according to this theory light was weightless, so how could the emission of sunlight compensate for the meteoric mass ...
... firmly established, and Mayer knew that according to this theory light was weightless, so how could the emission of sunlight compensate for the meteoric mass ...
Evolution of Primordial Magnetic Fields from Phase
... fields for galactic dynamos. It is, however, important to note that Bξ is strongly nB dependent for a given value of ξ. In particular, for causally-generated magnetic fields with nB ≥ 0 there is significant “magnetic power” only at small scales, and for ξ ≃ 1 Mpc the value of B1Mpc is extremely smal ...
... fields for galactic dynamos. It is, however, important to note that Bξ is strongly nB dependent for a given value of ξ. In particular, for causally-generated magnetic fields with nB ≥ 0 there is significant “magnetic power” only at small scales, and for ξ ≃ 1 Mpc the value of B1Mpc is extremely smal ...
Solar Flares: Magnetohydrodynamic Processes | SpringerLink
... lines reconnect to form a closed loop, then the upflows of the solar wind along the reconnected field lines collide each other to generate a shock inside the closed loop, thereby heating coronal plasma up to the typical temperature of a flare. However, Cargill and Priest (1982) later pointed out tha ...
... lines reconnect to form a closed loop, then the upflows of the solar wind along the reconnected field lines collide each other to generate a shock inside the closed loop, thereby heating coronal plasma up to the typical temperature of a flare. However, Cargill and Priest (1982) later pointed out tha ...
Solar energetic particle access to distant longitudes through
... cascading towards smaller scales. The radial and spectral evolution of turbulence in the heliosphere have been studied in several works over several decades. Many of the works, however, considered isotropic or slab turbulence (e.g. Tu et al. 1984; Tu 1987; Zhou & Matthaeus 1990; Vainio et al. 2003) ...
... cascading towards smaller scales. The radial and spectral evolution of turbulence in the heliosphere have been studied in several works over several decades. Many of the works, however, considered isotropic or slab turbulence (e.g. Tu et al. 1984; Tu 1987; Zhou & Matthaeus 1990; Vainio et al. 2003) ...
THE SPACE WEATHER OF PROXIMA CENTAURI b
... of the additional current generated by the temporal changes in the magnetic field. The timescale of the variations for Proximab are only of the order of a day. Further detailed and physically realistic modeling is needed in order to asses the full impact of these geomagnetic effects on a planetary a ...
... of the additional current generated by the temporal changes in the magnetic field. The timescale of the variations for Proximab are only of the order of a day. Further detailed and physically realistic modeling is needed in order to asses the full impact of these geomagnetic effects on a planetary a ...
ASTR 330: The Solar System - University of Maryland
... characteristic tail(s). • How many tails are there? ...
... characteristic tail(s). • How many tails are there? ...
The Limits of Our Solar System - Lunar and Planetary Institute
... the heliopause is the inner heliosheath and the region between the bow shock and the heliopause is the outer heliosheath. Plate 11 shows the equatorial plane from a model simulation of the heliospheric system (Müller et al., 2006). The color coding in the top panel gives the plasma temperature and i ...
... the heliopause is the inner heliosheath and the region between the bow shock and the heliopause is the outer heliosheath. Plate 11 shows the equatorial plane from a model simulation of the heliospheric system (Müller et al., 2006). The color coding in the top panel gives the plasma temperature and i ...
The Solar System and Beyond
... providing the logistics for efficient cooperation between scientists from various disciplines, so that the synergistic benefits can be optimized. ISSI’s primary focus has been on the Solar System, where the need for interdisciplinary studies has been strongest. However, it reaches out far beyond the ...
... providing the logistics for efficient cooperation between scientists from various disciplines, so that the synergistic benefits can be optimized. ISSI’s primary focus has been on the Solar System, where the need for interdisciplinary studies has been strongest. However, it reaches out far beyond the ...
The Sun`s journey through the local interstellar medium: the
... decrease by ≥20% from the cloud exterior to the solar location.2 In contrast, He and Ne ionizations, which require photons more energetic by > 50%, vary little. Guesstimates indicate that for ∼ 50% filtration of Ho , converting 20% of the H from Ho to H+ would raise the H pressure confining the pale ...
... decrease by ≥20% from the cloud exterior to the solar location.2 In contrast, He and Ne ionizations, which require photons more energetic by > 50%, vary little. Guesstimates indicate that for ∼ 50% filtration of Ho , converting 20% of the H from Ho to H+ would raise the H pressure confining the pale ...
Absorption of high-energy gamma rays in Cygnus X-3
... the system. We provide in Sect. 2 and in Appendix A a complete study of the absorption of GeV photons in the radiation field of an accretion disk. Long-term observations in X-rays revealed that Cygnus X-3 presents complex spectral and temporal features. Szostek et al. (2008) classified the X-ray spe ...
... the system. We provide in Sect. 2 and in Appendix A a complete study of the absorption of GeV photons in the radiation field of an accretion disk. Long-term observations in X-rays revealed that Cygnus X-3 presents complex spectral and temporal features. Szostek et al. (2008) classified the X-ray spe ...
PPT
... – w2 is real and decreases through zero, monotonic growth in perturbation. The marginal state is stationary (w=0) – Frequency (w) is complex and its Imaginary part decreases from + to -, a state of growing oscillations appears (overstability). Marginal state is oscillatory motion. ...
... – w2 is real and decreases through zero, monotonic growth in perturbation. The marginal state is stationary (w=0) – Frequency (w) is complex and its Imaginary part decreases from + to -, a state of growing oscillations appears (overstability). Marginal state is oscillatory motion. ...
Analytic Models for the Mechanical Structure of the Solar Core
... and present standard solar models (Pinsonneault 1998), which include helium and metal diffusion, both normalized to central values. These figures also show our fits to the ZAMS (present) SSM cores derived from our hyperbolic approximation in Section 4 below. The central values of pressure, density a ...
... and present standard solar models (Pinsonneault 1998), which include helium and metal diffusion, both normalized to central values. These figures also show our fits to the ZAMS (present) SSM cores derived from our hyperbolic approximation in Section 4 below. The central values of pressure, density a ...
The Sun as a star: observations of white-light flares - HAL-Insu
... flare. Furthermore, many flares were observed with no associated white-light emission and with no means to determine if this was because of instrumental limitations or because of the actual absence of WL emission. Recent studies (Jess et al. 2008; Wang 2009) identified WL emission in relatively smal ...
... flare. Furthermore, many flares were observed with no associated white-light emission and with no means to determine if this was because of instrumental limitations or because of the actual absence of WL emission. Recent studies (Jess et al. 2008; Wang 2009) identified WL emission in relatively smal ...
Relaxation of Blazar Induced Pair Beams in Cosmic Voids
... to constraint the EBL (e.g. Aharonian et al. 2006), recently multi-GeV and TeV blazars observations have also been used to constrain magnetic field in cosmic voids for the first time (Neronov & Vovk 2010; Tavecchio et al. 2010). In fact, for flat enough blazar’s spectra, the electromagnetic cascade ...
... to constraint the EBL (e.g. Aharonian et al. 2006), recently multi-GeV and TeV blazars observations have also been used to constrain magnetic field in cosmic voids for the first time (Neronov & Vovk 2010; Tavecchio et al. 2010). In fact, for flat enough blazar’s spectra, the electromagnetic cascade ...
Spectral properties, magnetic fields, and dust transport at lunar swirls
... Gamma (Fig. 4e, black arrow) has only moderate redness and band strength at its center, suggesting the swirl forming process may be less effective there. Central regions of highland swirls show only a decrease in redness relative to background values (Fig. 4d), and do not appear to have a red halo a ...
... Gamma (Fig. 4e, black arrow) has only moderate redness and band strength at its center, suggesting the swirl forming process may be less effective there. Central regions of highland swirls show only a decrease in redness relative to background values (Fig. 4d), and do not appear to have a red halo a ...
PDF only - at www.arxiv.org.
... component of a magnetic field, as suggested by the filamentary morphology. Consider first a horizontal thread supported against gravity, the field Bh needed for support is then Bh ~ (4π Σ┴ g)1/2. For the above values this corresponds to Bh ~ 24 μG which is less than the equipartition value of 100 μG ...
... component of a magnetic field, as suggested by the filamentary morphology. Consider first a horizontal thread supported against gravity, the field Bh needed for support is then Bh ~ (4π Σ┴ g)1/2. For the above values this corresponds to Bh ~ 24 μG which is less than the equipartition value of 100 μG ...
The Science Case for SPICA Far
... of dust grains with respect to the local magnetic field (Hildebrand 1998; Martin 1971). It is the potential to map magnetic field structures in the interstellar medium which motivates much of this experimental and observational work. Interferometric techniques have been applied to polarimetry at ≥ ...
... of dust grains with respect to the local magnetic field (Hildebrand 1998; Martin 1971). It is the potential to map magnetic field structures in the interstellar medium which motivates much of this experimental and observational work. Interferometric techniques have been applied to polarimetry at ≥ ...
Isotopes Tell Origin and Operation of the Sun
... Similar mass fractionation effects had been seen in neon isotopes of the Fayetteville meteorite in 1967 [33]. Two years later, Marti [34] discovered solar-type xenon in the Pesyanoe meteorite and noted that isotope abundances in solar-type xenon and those in the terrestrial atmosphere might “. . . b ...
... Similar mass fractionation effects had been seen in neon isotopes of the Fayetteville meteorite in 1967 [33]. Two years later, Marti [34] discovered solar-type xenon in the Pesyanoe meteorite and noted that isotope abundances in solar-type xenon and those in the terrestrial atmosphere might “. . . b ...
1. INTRODUCTION - Institut für Theoretische Astrophysik
... explanation of basal heating is that it may be caused by heating due to intrinsically weak magnetic Ðelds generated by the dynamo mechanism working at a very low stellar rotation rate or by convective turbulence of the partly ionized matter. Furthermore, those magnetic Ðelds could also be a leftover ...
... explanation of basal heating is that it may be caused by heating due to intrinsically weak magnetic Ðelds generated by the dynamo mechanism working at a very low stellar rotation rate or by convective turbulence of the partly ionized matter. Furthermore, those magnetic Ðelds could also be a leftover ...
Accretion and Current Discs Controlled by Strong Magnetic Field
... the mass of the dying star. The neutron star masses range from 1.4 to 3 MSun, where MSun = 2×1030 kg is a solar mass, 1.4 MSun is a Chandrasekhar limit, and 3 MSun is an Oppenheimer-Volkoff limit. The neutron stars consist mainly of neutrons. Radius of a neutron star is ~10 - 20 km. The material den ...
... the mass of the dying star. The neutron star masses range from 1.4 to 3 MSun, where MSun = 2×1030 kg is a solar mass, 1.4 MSun is a Chandrasekhar limit, and 3 MSun is an Oppenheimer-Volkoff limit. The neutron stars consist mainly of neutrons. Radius of a neutron star is ~10 - 20 km. The material den ...
PDF: 154K
... spatial scaling of the correlation time tðkÞ / km of the turbulent velocity field, where k is the small-scale wave number. In particular, the shear-current dynamo in a nonconvective turbulence occurs when the exponent mo1. For the Kolmogorov’s type turbulent convection, the exponent m ¼ 2=3 and sB ¼ ...
... spatial scaling of the correlation time tðkÞ / km of the turbulent velocity field, where k is the small-scale wave number. In particular, the shear-current dynamo in a nonconvective turbulence occurs when the exponent mo1. For the Kolmogorov’s type turbulent convection, the exponent m ¼ 2=3 and sB ¼ ...
PHY 380L Introduction to Plasma Physics Richard Fitzpatrick
... they are strongly affected by each others’ electromagnetic fields. Nevertheless, because the charges are no longer bound, their assemblage becomes capable of collective motions of great vigor and complexity. Such an assemblage is termed a plasma. Of course, bound systems can display extreme complexi ...
... they are strongly affected by each others’ electromagnetic fields. Nevertheless, because the charges are no longer bound, their assemblage becomes capable of collective motions of great vigor and complexity. Such an assemblage is termed a plasma. Of course, bound systems can display extreme complexi ...
Corona
A corona (Latin, 'crown') is an aura of plasma that surrounds the sun and other celestial bodies. The Sun's corona extends millions of kilometres into space and is most easily seen during a total solar eclipse, but it is also observable with a coronagraph. The word ""corona"" is a Latin word meaning ""crown"", from the Ancient Greek κορώνη (korōnē, “garland, wreath”).The high temperature of the Sun's corona gives it unusual spectral features, which led some in the 19th century to suggest that it contained a previously unknown element, ""coronium"". Instead, these spectral features have since been explained by highly ionized iron (Fe-XIV). Bengt Edlén, following the work of Grotrian (1939), first identified the coronal lines in 1940 (observed since 1869) as transitions from low-lying metastable levels of the ground configuration of highly ionised metals (the green Fe-XIV line at 5303 Å, but also the red line Fe-X at 6374 Å). These high stages of ionisation indicate a plasma temperature in excess of 1,000,000 kelvin, much hotter than the surface of the sun.Light from the corona comes from three primary sources, which are called by different names although all of them share the same volume of space. The K-corona (K for kontinuierlich, ""continuous"" in German) is created by sunlight scattering off free electrons; Doppler broadening of the reflected photospheric absorption lines completely obscures them, giving the spectral appearance of a continuum with no absorption lines. The F-corona (F for Fraunhofer) is created by sunlight bouncing off dust particles, and is observable because its light contains the Fraunhofer absorption lines that are seen in raw sunlight; the F-corona extends to very high elongation angles from the Sun, where it is called the zodiacal light. The E-corona (E for emission) is due to spectral emission lines produced by ions that are present in the coronal plasma; it may be observed in broad or forbidden or hot spectral emission lines and is the main source of information about the corona's composition.