Influence of extreme ultraviolet radiation on the Pv ionization fraction
... reconcile with each other. The widely accepted presence of clumping in hot star winds implies a significant reduction of observational mass-loss rate estimates from diagnostics that depend on the square of the density. Moreover, the ultraviolet P V resonance lines indicate a possible need for an eve ...
... reconcile with each other. The widely accepted presence of clumping in hot star winds implies a significant reduction of observational mass-loss rate estimates from diagnostics that depend on the square of the density. Moreover, the ultraviolet P V resonance lines indicate a possible need for an eve ...
The density of very massive evolved galaxies to z≃ 1.7
... values, we integrated the K-band luminosity function (LF) of local early-type galaxies, derived by Kochanek et al. (2001), described by M ∗ K = −24.3 ± 0.06 and ∗ = 1.5 ± 0.2 × 10−3 Mpc−3 . The lower bound to the integration has been derived in two independent ways. The first one lies in deriving t ...
... values, we integrated the K-band luminosity function (LF) of local early-type galaxies, derived by Kochanek et al. (2001), described by M ∗ K = −24.3 ± 0.06 and ∗ = 1.5 ± 0.2 × 10−3 Mpc−3 . The lower bound to the integration has been derived in two independent ways. The first one lies in deriving t ...
Pulsars as Astrophysical Laboratories for Nuclear and Particle Physics
... the emitted electromagnetic radiation, (2) accretion-powered (X-ray) pulsars, where the gravitational 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. T ...
... the emitted electromagnetic radiation, (2) accretion-powered (X-ray) pulsars, where the gravitational 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. T ...
The double-pulsar PSR J0737−3039A/B
... makes J0737−3039A’s orbit the tightest among those of all known binary pulsars in eccentric systems. The pulsar mass function was calculated and resulted 0.29 M . A strong constraint on the nature of PSR J0737−3039A companion came few days later from the first fit of a binary model to the times of ...
... makes J0737−3039A’s orbit the tightest among those of all known binary pulsars in eccentric systems. The pulsar mass function was calculated and resulted 0.29 M . A strong constraint on the nature of PSR J0737−3039A companion came few days later from the first fit of a binary model to the times of ...
Gamma-ray burst investigation via polarimetry and spectroscopy
... Spectra Based on the knowledge gained from observation in the keV– MeV range several possible radiation mechanisms exist, all of which produce characteristic spectra in the super-MeV range. Two main classes of models (see Mészáros 2006) have been discussed. (1) Synchrotron/inverse Compton emission o ...
... Spectra Based on the knowledge gained from observation in the keV– MeV range several possible radiation mechanisms exist, all of which produce characteristic spectra in the super-MeV range. Two main classes of models (see Mészáros 2006) have been discussed. (1) Synchrotron/inverse Compton emission o ...
The Interstellar Medium in High Redshift Galaxies Comes of Age
... molecular gas in galaxy formation and for providing fundamental constraints on galaxy evolution. To date, a fairly small number of species, other than CO, have been detected at z > 2 (e.g. HCN, HNC, CN, H2 O, HCO+ ) and used as tracers of molecular gas. Recent observations with the Herschel Space Ob ...
... molecular gas in galaxy formation and for providing fundamental constraints on galaxy evolution. To date, a fairly small number of species, other than CO, have been detected at z > 2 (e.g. HCN, HNC, CN, H2 O, HCO+ ) and used as tracers of molecular gas. Recent observations with the Herschel Space Ob ...
Theory of cooling neutron stars versus observations
... Its composition is very uncertain. It may be the same as in the outer core or essentially different. In particular, hyperons may appear there in addition to nucleons. Another possibility is the appearance of exotic matter (pion or kaon condensates or strange quark matter or mixed phases, as reviewed ...
... Its composition is very uncertain. It may be the same as in the outer core or essentially different. In particular, hyperons may appear there in addition to nucleons. Another possibility is the appearance of exotic matter (pion or kaon condensates or strange quark matter or mixed phases, as reviewed ...
Asymmetric Star Formation Efficiency Due to Ram Pressure Stripping
... processes, considering dark matter and gas particles. The gas particles fall into the centres of dark matter haloes, depending on how they have cooled and whether they reach a density greater than a certain threshold, they can be converted into star particles or not. The rate at which stars are form ...
... processes, considering dark matter and gas particles. The gas particles fall into the centres of dark matter haloes, depending on how they have cooled and whether they reach a density greater than a certain threshold, they can be converted into star particles or not. The rate at which stars are form ...
Quasars and Blazars
... sufficient to produce emission lines that are observable over the non-thermal (synchrotron) continuum. In other words, the lines are there, but they are just very weak. This is similar to the beaming hypothesis, but without requiring the stronger continuum. These issues will be discussed further in ...
... sufficient to produce emission lines that are observable over the non-thermal (synchrotron) continuum. In other words, the lines are there, but they are just very weak. This is similar to the beaming hypothesis, but without requiring the stronger continuum. These issues will be discussed further in ...
pdf
... a single 1024 × 1024 CCD would provide 25 × 25 resolution elements which may be much harder to get in, say, a micro-calorimeter array device. Spreading the events over ≈ 40 × 40 pixels will relax calibration demands and reduce pixel pile-up for even the brightest sources. By using reflection from a ...
... a single 1024 × 1024 CCD would provide 25 × 25 resolution elements which may be much harder to get in, say, a micro-calorimeter array device. Spreading the events over ≈ 40 × 40 pixels will relax calibration demands and reduce pixel pile-up for even the brightest sources. By using reflection from a ...
Richard Congdon. pdf
... are absorbed making their detection almost impossible at the surface of the Earth (Pinkau, 2009). The gamma-ray line spectra produced by the galactic sources provide additional information, via the Doppler Effect, about the speed of ejection from the star and the direction of rotation of the arm of ...
... are absorbed making their detection almost impossible at the surface of the Earth (Pinkau, 2009). The gamma-ray line spectra produced by the galactic sources provide additional information, via the Doppler Effect, about the speed of ejection from the star and the direction of rotation of the arm of ...
Accretion models
... •This source must also be responsible for the other peculiarities: • Broad emission lines • “Veiling” • NIR excess • Forbidden emission lines LJ , good measure of L*, because the stellar luminosity peaks in J band ...
... •This source must also be responsible for the other peculiarities: • Broad emission lines • “Veiling” • NIR excess • Forbidden emission lines LJ , good measure of L*, because the stellar luminosity peaks in J band ...
ROSAT Isolated Neutron Stars
... Electrons move much more easily along B than across B Thermal conduction is highly anisotropic inside a NS: Kpar >> Kperp until EF >> hνB or ρ >> 104(B/1012 G)3/2 g/cm3 Envelope scaleheight L ≈ 10 m << R, B ~ const and heat transport locally 1D ...
... Electrons move much more easily along B than across B Thermal conduction is highly anisotropic inside a NS: Kpar >> Kperp until EF >> hνB or ρ >> 104(B/1012 G)3/2 g/cm3 Envelope scaleheight L ≈ 10 m << R, B ~ const and heat transport locally 1D ...
Galaxies
... • It depends how fast the gas is used up to form galaxies • If star formation is fast, no gas is left elliptical galaxy • If star formation is slow, gas forms disk spiral galaxy ...
... • It depends how fast the gas is used up to form galaxies • If star formation is fast, no gas is left elliptical galaxy • If star formation is slow, gas forms disk spiral galaxy ...
The history of a discovery - Institut d`Astrophysique Spatiale
... visible vs infrared output • the heavy elements (and associated dust) abundance in the universe is increasing with time • a naïve view would thus predict a decreasing FIR/visible ratio with redshift • a few galaxies had been shown to have a large ratio but the bulk of the galaxies were expected to h ...
... visible vs infrared output • the heavy elements (and associated dust) abundance in the universe is increasing with time • a naïve view would thus predict a decreasing FIR/visible ratio with redshift • a few galaxies had been shown to have a large ratio but the bulk of the galaxies were expected to h ...
Towards Planetesimals in the Disk around TW Hya: 3.5 centimeter
... bolster this conclusion. Observations of the X-ray spectrum with XMM-Newton (Stelzer & Schmitt 2004) and Chandra (Kastner et al. 2002) indicate electron densities two orders of magnitude higher than typically found in stellar coronae. In addition, the X-ray emitting material appears to be depleted o ...
... bolster this conclusion. Observations of the X-ray spectrum with XMM-Newton (Stelzer & Schmitt 2004) and Chandra (Kastner et al. 2002) indicate electron densities two orders of magnitude higher than typically found in stellar coronae. In addition, the X-ray emitting material appears to be depleted o ...
- Astronomy and Astrophysics Supplement Series
... doubled. The nominal roll angle is −167◦ and the wobble direction is at PA = 122◦ . The F W HM of this smoothed image is 11.600 × 7.400 ...
... doubled. The nominal roll angle is −167◦ and the wobble direction is at PA = 122◦ . The F W HM of this smoothed image is 11.600 × 7.400 ...
Neutron Stars and the Determination of the Dense Matter Equation
... A physical understanding of the behaviour of cold ultra-dense matter – at and above nuclear density – can only be achieved by the study of neutron stars. The surface thermal emission from neutron stars in quiescent low-mass X-ray binaries (qLMXBs) inside globular clusters has proven useful for that ...
... A physical understanding of the behaviour of cold ultra-dense matter – at and above nuclear density – can only be achieved by the study of neutron stars. The surface thermal emission from neutron stars in quiescent low-mass X-ray binaries (qLMXBs) inside globular clusters has proven useful for that ...
A bright, dust-obscured, millimetre
... The median redshift of the bright SMG population, based on spectroscopic and photometric redshifts, is ∼2.5, with approximately 50 per cent of the population at 1.9 < z < 2.9 (Aretxaga et al. 2003; Chapman et al. 2003, 2005; Pope et al. 2005; Aretxaga et al. 2007). Scaling the observed flux densitie ...
... The median redshift of the bright SMG population, based on spectroscopic and photometric redshifts, is ∼2.5, with approximately 50 per cent of the population at 1.9 < z < 2.9 (Aretxaga et al. 2003; Chapman et al. 2003, 2005; Pope et al. 2005; Aretxaga et al. 2007). Scaling the observed flux densitie ...
Orbital period decay of compact black hole X
... detailed evolutionary sequences of a BHXB with an initial orbital period of 0.9 d, which consist of a 5.0 M BH and a 3.0 M donor star. The calculation shows that if the fraction of the transferred mass feeds into the circumbinary disk δ is greater than 0.00035, the mass transfer becomes dynamicall ...
... detailed evolutionary sequences of a BHXB with an initial orbital period of 0.9 d, which consist of a 5.0 M BH and a 3.0 M donor star. The calculation shows that if the fraction of the transferred mass feeds into the circumbinary disk δ is greater than 0.00035, the mass transfer becomes dynamicall ...
masses of star clusters in the nuclei of bulgeless spiral galaxies
... NGC 4449 using population synthesis models. They estimate an age of 107 yr, in agreement with Gelatt et al. (2001). They infer a lower limit for the mass, which is 4 ; 105 M . The available sizes, masses, and ages suggest kinship between NCs and either globular clusters (GCs), super star clusters ...
... NGC 4449 using population synthesis models. They estimate an age of 107 yr, in agreement with Gelatt et al. (2001). They infer a lower limit for the mass, which is 4 ; 105 M . The available sizes, masses, and ages suggest kinship between NCs and either globular clusters (GCs), super star clusters ...
Seminar 2
... The redshift range discussed in detail in this paper is 0 < z < 1. At higher redshifts it becomes very difficult to determine the morphology of galaxies. Observational results indicate that the galaxies have only taken on their familiar appearance relatively recently. The galaxy population starts to ...
... The redshift range discussed in detail in this paper is 0 < z < 1. At higher redshifts it becomes very difficult to determine the morphology of galaxies. Observational results indicate that the galaxies have only taken on their familiar appearance relatively recently. The galaxy population starts to ...
ON THE RADIAL ONSET OF CLUMPING IN THE WIND OF... J. M. Torrejón , N. S. Schulz , M. A. Nowak
... Cassinelly 2007). One of the models developed to accommodate these finding suggests that sub-surface convection may play a role in massive stars, resulting in surface magnetic spots and causing the clumping to already originate at the photosphere (Cantiello & Braithwaite 2011). In high-mass X-ray bin ...
... Cassinelly 2007). One of the models developed to accommodate these finding suggests that sub-surface convection may play a role in massive stars, resulting in surface magnetic spots and causing the clumping to already originate at the photosphere (Cantiello & Braithwaite 2011). In high-mass X-ray bin ...
SPITZER/MIPS 24 µm OBSERVATIONS OF GALAXY CLUSTERS
... the galaxies in the Spitzer Infrared Nearby Galaxies Survey (Dale et al. 2007), and at each redshift adopt the median conversion factor from F24µm to F8−1000µm given by these models. At 0.4 . z . 0.6, the error due to the adopted conversion factor is ∼ 20%, but the error increases to a factor of 1.5 ...
... the galaxies in the Spitzer Infrared Nearby Galaxies Survey (Dale et al. 2007), and at each redshift adopt the median conversion factor from F24µm to F8−1000µm given by these models. At 0.4 . z . 0.6, the error due to the adopted conversion factor is ∼ 20%, but the error increases to a factor of 1.5 ...
PPT
... •The distance to NGC is 80 million light years, which Mkn 205 is 14 times farther away at a distance of 1 billion light year. •The very distant quasar is nearly as bright as the much closer galaxy. The extraordinary brightness of quasars, which is a blending of the term quasi-stellar radio source, i ...
... •The distance to NGC is 80 million light years, which Mkn 205 is 14 times farther away at a distance of 1 billion light year. •The very distant quasar is nearly as bright as the much closer galaxy. The extraordinary brightness of quasars, which is a blending of the term quasi-stellar radio source, i ...
Astrophysical X-ray source
Astrophysical X-ray sources are astronomical objects with physical properties which result in the emission of X-rays.There are a number of types of astrophysical objects which emit X-rays, from galaxy clusters, through black holes in active galactic nuclei (AGN) to galactic objects such as supernova remnants, stars, and binary stars containing a white dwarf (cataclysmic variable stars and super soft X-ray sources), neutron star or black hole (X-ray binaries). Some solar system bodies emit X-rays, the most notable being the Moon, although most of the X-ray brightness of the Moon arises from reflected solar X-rays. A combination of many unresolved X-ray sources is thought to produce the observed X-ray background. The X-ray continuum can arise from bremsstrahlung, either magnetic or ordinary Coulomb, black-body radiation, synchrotron radiation, inverse Compton scattering of lower-energy photons be relativistic electrons, knock-on collisions of fast protons with atomic electrons, and atomic recombination, with or without additional electron transitions.Furthermore, celestial entities in space are discussed as celestial X-ray sources. The origin of all observed astronomical X-ray sources is in, near to, or associated with a coronal cloud or gas at coronal cloud temperatures for however long or brief a period.