A radio pulsing white dwarf binary star
... White dwarfs are compact stars, similar in size to Earth but ∼ 200,000 times more massive1 . Isolated white dwarfs emit most of their power from ultraviolet to near-infrared wavelengths, but when in close orbits with less dense stars, white dwarfs can strip material from their companions, and the re ...
... White dwarfs are compact stars, similar in size to Earth but ∼ 200,000 times more massive1 . Isolated white dwarfs emit most of their power from ultraviolet to near-infrared wavelengths, but when in close orbits with less dense stars, white dwarfs can strip material from their companions, and the re ...
Is the central binary system of the planetary nebula Henize 2
... interestingly, in the study by Weidmann and Gamen (2011) there are several PNe that show a wide He II 5412 Å absorption line with a weak emission feature in the center of the wide absorption line. This forms a spectral structure similar to that of Henize 2–428. The most noticeable examples of this ...
... interestingly, in the study by Weidmann and Gamen (2011) there are several PNe that show a wide He II 5412 Å absorption line with a weak emission feature in the center of the wide absorption line. This forms a spectral structure similar to that of Henize 2–428. The most noticeable examples of this ...
Stellar Physics
... this is called brightness and is in effect the apparent brightness at the surface of the star. From the Stefan-Boltzmann law for a black-body: Flux = σT 4 where T is the temperature in kelvin (K) and σ is the Stefan-Boltzmann constant ( σ = 5.67 x 10 -8 J s -1 m -2 K -4 ) which gives the flux in J s ...
... this is called brightness and is in effect the apparent brightness at the surface of the star. From the Stefan-Boltzmann law for a black-body: Flux = σT 4 where T is the temperature in kelvin (K) and σ is the Stefan-Boltzmann constant ( σ = 5.67 x 10 -8 J s -1 m -2 K -4 ) which gives the flux in J s ...
G030163-03 - DCC
... Collision of Two 10 M Black Holes Analytic Extension From Inspiral (effective one body) ...
... Collision of Two 10 M Black Holes Analytic Extension From Inspiral (effective one body) ...
THE SHAPES OF ATOMIC LINES FROM THE SURFACES OF
... not at the rotation pole is effectively smeared into an axisymmetric belt when averaged over many spin periods. This is to be expected for the spin frequencies k10 Hz of neutron stars in LMXBs and the integration times of seconds typical of current high-resolution spectroscopic measurements. We ther ...
... not at the rotation pole is effectively smeared into an axisymmetric belt when averaged over many spin periods. This is to be expected for the spin frequencies k10 Hz of neutron stars in LMXBs and the integration times of seconds typical of current high-resolution spectroscopic measurements. We ther ...
Unresolved Stellar Populations
... • An SSP generally fades and becomes redder with increasing age due to the decrease of the MS extension and He-burning luminosity. These general trends are briefly interrupted, especially when the K band is involved, by the appearance of a large number of red He-burning stars at several ×107 yrs and ...
... • An SSP generally fades and becomes redder with increasing age due to the decrease of the MS extension and He-burning luminosity. These general trends are briefly interrupted, especially when the K band is involved, by the appearance of a large number of red He-burning stars at several ×107 yrs and ...
AST1100 Lecture Notes
... It is thought that neutron stars have solid outer crusts comprised of heavy nuclei (Fe) and electrons. Interior to this crust the material is comprised mostly of neutrons, with a small percentage of protons and electrons as well. At a sufficiently deep level the neutron density may become high enoug ...
... It is thought that neutron stars have solid outer crusts comprised of heavy nuclei (Fe) and electrons. Interior to this crust the material is comprised mostly of neutrons, with a small percentage of protons and electrons as well. At a sufficiently deep level the neutron density may become high enoug ...
Article PDF - IOPscience
... WASP-South and FTS transit light curves of WASP-19 using the Markov-chain Monte Carlo (MCMC) routined described in Collier Cameron et al. (2007) to derive the stellar density and its uncertainty. The code uses the MCMC approach to simultaneously solve for the orbital and physical properties of the s ...
... WASP-South and FTS transit light curves of WASP-19 using the Markov-chain Monte Carlo (MCMC) routined described in Collier Cameron et al. (2007) to derive the stellar density and its uncertainty. The code uses the MCMC approach to simultaneously solve for the orbital and physical properties of the s ...
AST1100 Lecture Notes
... It is thought that neutron stars have solid outer crusts comprised of heavy nuclei (Fe) and electrons. Interior to this crust the material is comprised mostly of neutrons, with a small percentage of protons and electrons as well. At a sufficiently deep level the neutron density may become high enoug ...
... It is thought that neutron stars have solid outer crusts comprised of heavy nuclei (Fe) and electrons. Interior to this crust the material is comprised mostly of neutrons, with a small percentage of protons and electrons as well. At a sufficiently deep level the neutron density may become high enoug ...
Dark Stars: Dark Matter Annihilation in the First Stars.
... • Very few ionizing photons, just too cool. ...
... • Very few ionizing photons, just too cool. ...
AST1100 Lecture Notes
... For M = M (where M is the mass which remained in the degenerate core, the star originally had more mass which was blown off) the radius of the white dwarf is similar to the radius of the Earth. A white dwarf is thus extremely dense, one solar mass compressed roughly to the size of the Earth. There ...
... For M = M (where M is the mass which remained in the degenerate core, the star originally had more mass which was blown off) the radius of the white dwarf is similar to the radius of the Earth. A white dwarf is thus extremely dense, one solar mass compressed roughly to the size of the Earth. There ...
ISA_lecture01 - School of Physics
... shape, and (c) has cleared the neighbourhood around its orbit. A “dwarf planet” is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, (c) has not cleared t ...
... shape, and (c) has cleared the neighbourhood around its orbit. A “dwarf planet” is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, (c) has not cleared t ...
The Milky Way - National Tsing Hua University
... Twisted magnetic fields help to confine the material in the jet and to produce synchrotron radiation. ...
... Twisted magnetic fields help to confine the material in the jet and to produce synchrotron radiation. ...
HMM词性标注
... In the simple spherical accretion model, Eddington accretion rate is a maximum possible accretion rate for mass M. This critical rate can easily be exceeded with the models that are not spherically symmetric, such as mass accretion occurs in a disk. （accrete ionized hydrogen gas） The major problem w ...
... In the simple spherical accretion model, Eddington accretion rate is a maximum possible accretion rate for mass M. This critical rate can easily be exceeded with the models that are not spherically symmetric, such as mass accretion occurs in a disk. （accrete ionized hydrogen gas） The major problem w ...
UMich w/s - Royal Observatory, Edinburgh
... There is a well-established half-light size bi-modality all systems with size ~ < 40pc are purely stellar −16< Mv < 0 (!!) M/L ~ 3; e.g. UCDs, Hilker et al 07; Rejkuba et al 07 all systems with size greater than ~120pc have a dark-matter halo There are no known (virial equilibrium) galaxies with ...
... There is a well-established half-light size bi-modality all systems with size ~ < 40pc are purely stellar −16< Mv < 0 (!!) M/L ~ 3; e.g. UCDs, Hilker et al 07; Rejkuba et al 07 all systems with size greater than ~120pc have a dark-matter halo There are no known (virial equilibrium) galaxies with ...
Compact objects for everyone: I. White dwarf stars - Rose
... ‘Little Green Men’. However, by the beginning of 1968, Hewish, Bell and collaborators had found three additional pulsating sources of radio waves, or pulsars [9]. The final explanation of these enigmatic sources was due to Gold shortly after Hewish and Bell published their findings [10, 11]. Gold su ...
... ‘Little Green Men’. However, by the beginning of 1968, Hewish, Bell and collaborators had found three additional pulsating sources of radio waves, or pulsars [9]. The final explanation of these enigmatic sources was due to Gold shortly after Hewish and Bell published their findings [10, 11]. Gold su ...
On the correlation between stellar chromospheric flux and the
... encircling the star is uniformly filled with a homogeneous condensation, but that several clumps of material are formed inside it. They absorb at different wavelengths because of their individual radial velocities. Since the matter comes from the evaporating planet, it initially has its orbital angu ...
... encircling the star is uniformly filled with a homogeneous condensation, but that several clumps of material are formed inside it. They absorb at different wavelengths because of their individual radial velocities. Since the matter comes from the evaporating planet, it initially has its orbital angu ...
PHY418 Particle Astrophysics
... • But it’s quite hard to work out how they do it • magnetic geometry at the termination shock must be quasiperpendicular, which disfavours diffusive shock acceleration • but maybe enough small-scale turbulence is generated at the shock • the expected electron power law of E−2.2 is right for the Crab ...
... • But it’s quite hard to work out how they do it • magnetic geometry at the termination shock must be quasiperpendicular, which disfavours diffusive shock acceleration • but maybe enough small-scale turbulence is generated at the shock • the expected electron power law of E−2.2 is right for the Crab ...
Ion-supported tori: a thermal bremsstrahlung model for the X
... emerged in relation to recent discussions of energy advection solutions (see Begelman 1978 and Abramowicz et al. 1988, for high-M, optically thick systems, and Rees et al. 1982; Abramowicz et al. 1995 and Narayan & Yi 1994, 1995a, b for the low-M, optically thin solution relevant here) for accretion ...
... emerged in relation to recent discussions of energy advection solutions (see Begelman 1978 and Abramowicz et al. 1988, for high-M, optically thick systems, and Rees et al. 1982; Abramowicz et al. 1995 and Narayan & Yi 1994, 1995a, b for the low-M, optically thin solution relevant here) for accretion ...
Script Chapter 7 part 2
... CHAPTER 7. PLANET FORMATION – the gas in the disk is assumed to move in quasi-Keplerian orbits and the specific ...
... CHAPTER 7. PLANET FORMATION – the gas in the disk is assumed to move in quasi-Keplerian orbits and the specific ...
Space astrometry 2: Scientific results from Hipparcos
... • total surface density projected on the plane (scale height) • density + velocity distribution → potential (K-z relation) Important for: • physical/chemical evolution of star formation • disk stability and properties of dark matter • Galactic escape velocity (~500 km/s; also runaway + hypervelocity ...
... • total surface density projected on the plane (scale height) • density + velocity distribution → potential (K-z relation) Important for: • physical/chemical evolution of star formation • disk stability and properties of dark matter • Galactic escape velocity (~500 km/s; also runaway + hypervelocity ...
with answers
... producing enough light to outshine a galaxy. When two atomic nuclei join to form a new, heavier nucleus and release energy. A type of fusion that occurs due to the extreme high temperatures in stars or in thermonuclear weapons. The process of creating new atomic nuclei from the fusion of smaller nuc ...
... producing enough light to outshine a galaxy. When two atomic nuclei join to form a new, heavier nucleus and release energy. A type of fusion that occurs due to the extreme high temperatures in stars or in thermonuclear weapons. The process of creating new atomic nuclei from the fusion of smaller nuc ...
Cygnus X-1
Cygnus X-1 (abbreviated Cyg X-1) is a well-known galactic X-ray source, thought to be a black hole, in the constellation Cygnus. It was discovered in 1964 during a rocket flight and is one of the strongest X-ray sources seen from Earth, producing a peak X-ray flux density of 6977229999999999999♠2.3×10−23 Wm−2 Hz−1 (7003230000000000000♠2.3×103 Jansky). Cygnus X-1 was the first X-ray source widely accepted to be a black hole and it remains among the most studied astronomical objects in its class. The compact object is now estimated to have a mass about 14.8 times the mass of the Sun and has been shown to be too small to be any known kind of normal star, or other likely object besides a black hole. If so, the radius of its event horizon is about 7004440000000000000♠44 km.Cygnus X-1 belongs to a high-mass X-ray binary system about 7019574266339685654♠6070 ly from the Sun that includes a blue supergiant variable star designated HDE 226868 which it orbits at about 0.2 AU, or 20% of the distance from the Earth to the Sun. A stellar wind from the star provides material for an accretion disk around the X-ray source. Matter in the inner disk is heated to millions of degrees, generating the observed X-rays. A pair of jets, arranged perpendicular to the disk, are carrying part of the energy of the infalling material away into interstellar space.This system may belong to a stellar association called Cygnus OB3, which would mean that Cygnus X-1 is about five million years old and formed from a progenitor star that had more than 7001400000000000000♠40 solar masses. The majority of the star's mass was shed, most likely as a stellar wind. If this star had then exploded as a supernova, the resulting force would most likely have ejected the remnant from the system. Hence the star may have instead collapsed directly into a black hole.Cygnus X-1 was the subject of a friendly scientific wager between physicists Stephen Hawking and Kip Thorne in 1975, with Hawking betting that it was not a black hole. He conceded the bet in 1990 after observational data had strengthened the case that there was indeed a black hole in the system. This hypothesis has not been confirmed due to a lack of direct observation but has generally been accepted from indirect evidence.