observability and uv coverage
... During the imaging process (this volume, C. Hani rst lecture), a single dish telescope can be viewed as a low pass lter with cut-o frequency D= where D is the telescope diameter and is the wavelength. The incoming wavefront is thus spatially ltered by the telescope and all spatial frequencie ...
... During the imaging process (this volume, C. Hani rst lecture), a single dish telescope can be viewed as a low pass lter with cut-o frequency D= where D is the telescope diameter and is the wavelength. The incoming wavefront is thus spatially ltered by the telescope and all spatial frequencie ...
Dynamics of the Milky Way
... • Relaxation is expected to have occurred in some globular clusters and the densest nuclei of galaxies Dynamics of the Milky Way --- Part 1: Introduction and Fundamental Stellar Dynamics ...
... • Relaxation is expected to have occurred in some globular clusters and the densest nuclei of galaxies Dynamics of the Milky Way --- Part 1: Introduction and Fundamental Stellar Dynamics ...
Discovery of concentric broken rings at sub
... the central ∼200 au region. We identify several new structures that are either spiral-like or ring-like. A spiral arm S1, detected in Ks, starts as close as ∼0.500 to the east of the star and winds to the southeast (Fig. 1 and 1 & B.1, b for annotations). A more extended region is visible as a possi ...
... the central ∼200 au region. We identify several new structures that are either spiral-like or ring-like. A spiral arm S1, detected in Ks, starts as close as ∼0.500 to the east of the star and winds to the southeast (Fig. 1 and 1 & B.1, b for annotations). A more extended region is visible as a possi ...
Symbiotic Stars as Laboratories for the Study of
... Abstract Symbiotic binary stars typically consist of a white dwarf (WD) that accretes material from the wind of a companion red giant. Orbital periods for these binaries are on the order of years, and their relatively small optical outbursts tend to occur every few years to decades. In some symbioti ...
... Abstract Symbiotic binary stars typically consist of a white dwarf (WD) that accretes material from the wind of a companion red giant. Orbital periods for these binaries are on the order of years, and their relatively small optical outbursts tend to occur every few years to decades. In some symbioti ...
The role of black holes in galaxy formation and evolution
... accretion rates to provide the energy that is needed to maintain it at constant temperature46–48, either through a continuous series of minor events44,45,49, or through episodic quasar activity50,51. The strongest evidence for this loop cycle is in galaxy clusters. Its action reduces considerably th ...
... accretion rates to provide the energy that is needed to maintain it at constant temperature46–48, either through a continuous series of minor events44,45,49, or through episodic quasar activity50,51. The strongest evidence for this loop cycle is in galaxy clusters. Its action reduces considerably th ...
Max Planck Institute for Gravitational Physics
... BUT INCREASE in W (DECREASE OF |W|) is more important than decrease in K since (I) STARS that LEAVE the cluster were not the faster before receiving the kick and (II) since Kf is the sum of Ki and Kext! ...
... BUT INCREASE in W (DECREASE OF |W|) is more important than decrease in K since (I) STARS that LEAVE the cluster were not the faster before receiving the kick and (II) since Kf is the sum of Ki and Kext! ...
Stars
... • Luminosity is measured in units of energy emitted per second, or watts. The Sun’s luminosity is about 3.85 × 1026 W. The values for other stars vary widely, from about 0.0001 to more than 1 million times the Sun’s luminosity. No other stellar property varies as much. ...
... • Luminosity is measured in units of energy emitted per second, or watts. The Sun’s luminosity is about 3.85 × 1026 W. The values for other stars vary widely, from about 0.0001 to more than 1 million times the Sun’s luminosity. No other stellar property varies as much. ...
Lecture 2. Isolated Neutron Stars – I.
... Close binary systems About ½ of massive stars Are members of close binary systems. Now we know many dozens of close binary systems with neutron stars. ...
... Close binary systems About ½ of massive stars Are members of close binary systems. Now we know many dozens of close binary systems with neutron stars. ...
Spectroscopic Variability of Supergiant Star HD14134, B3Ia
... of the HD14134 supergiant indicates rapidly variable structure. On December 25, 2013 and on August 27, 2014, the Hα profile in the spectrum of the star HD14134 had the shape of an inverse P Cygni profile (Fig.1a). Another variability pattern, where Hα appears only in weak emission (13/02/2016). The Hα ...
... of the HD14134 supergiant indicates rapidly variable structure. On December 25, 2013 and on August 27, 2014, the Hα profile in the spectrum of the star HD14134 had the shape of an inverse P Cygni profile (Fig.1a). Another variability pattern, where Hα appears only in weak emission (13/02/2016). The Hα ...
Spectroscopic Variability of Supergiant Star HD14134, B3Ia
... of the HD14134 supergiant indicates rapidly variable structure. On December 25, 2013 and on August 27, 2014, the Hα profile in the spectrum of the star HD14134 had the shape of an inverse P Cygni profile (Fig.1a). Another variability pattern, where Hα appears only in weak emission (13/02/2016). The Hα ...
... of the HD14134 supergiant indicates rapidly variable structure. On December 25, 2013 and on August 27, 2014, the Hα profile in the spectrum of the star HD14134 had the shape of an inverse P Cygni profile (Fig.1a). Another variability pattern, where Hα appears only in weak emission (13/02/2016). The Hα ...
The local spiral structure of the Milky Way
... main arc of the Local Arm. Instead, these sources, as well as G059.78+00.06 and ON 1, branch off and curve inward in the Milky Way. As the dotted line in Fig. 2 suggests, these sources trace what appears to be a high-inclination spur bridging the Local Arm to the Sagittarius Arm near l ≈ 50°. Additi ...
... main arc of the Local Arm. Instead, these sources, as well as G059.78+00.06 and ON 1, branch off and curve inward in the Milky Way. As the dotted line in Fig. 2 suggests, these sources trace what appears to be a high-inclination spur bridging the Local Arm to the Sagittarius Arm near l ≈ 50°. Additi ...
The fate of black hole singularities and the parameters of the
... After N generations the ensemble then defines a probability distribution function ρN (p) on P. To give meaning to the postulate that the random steps in the parameter space are small, we may require that the mean size of the random steps in the parameter space is small compared to the width of the p ...
... After N generations the ensemble then defines a probability distribution function ρN (p) on P. To give meaning to the postulate that the random steps in the parameter space are small, we may require that the mean size of the random steps in the parameter space is small compared to the width of the p ...
The role of black holes in galaxy formation and evolution
... The gas in massive galaxies, groups and clusters is hot and radiates copiously in X-rays. The problem of explaining why this gas does not quickly cool off is known as the ‘cooling flow’ problem. This problem has been heavily investigated in galaxy clusters, where the observational constraints are pa ...
... The gas in massive galaxies, groups and clusters is hot and radiates copiously in X-rays. The problem of explaining why this gas does not quickly cool off is known as the ‘cooling flow’ problem. This problem has been heavily investigated in galaxy clusters, where the observational constraints are pa ...
Chapter18.1
... • How were neutron stars discovered? – Beams of radiation from a rotating neutron star sweep through space like lighthouse beams, making them appear to pulse. – Observations of these pulses were the first evidence for neutron stars. ...
... • How were neutron stars discovered? – Beams of radiation from a rotating neutron star sweep through space like lighthouse beams, making them appear to pulse. – Observations of these pulses were the first evidence for neutron stars. ...
Chapter 4 On the possibility of a helium white dwarf donor in the
... Abstract 2S 0918–549 is a low-mass X-ray binary (LMXB) with a low optical to X-ray flux ratio. Probably it is an ultracompact binary with an orbital period shorter than 60 min. Such binaries cannot harbor hydrogen-rich donor stars. As with other (sometimes confirmed) ultracompact LMXBs, 2S 0918–549 ...
... Abstract 2S 0918–549 is a low-mass X-ray binary (LMXB) with a low optical to X-ray flux ratio. Probably it is an ultracompact binary with an orbital period shorter than 60 min. Such binaries cannot harbor hydrogen-rich donor stars. As with other (sometimes confirmed) ultracompact LMXBs, 2S 0918–549 ...
White dwarfs from GAIA: The 7th dimension
... • The white dwarf luminosity function of Gaia is a sensitive probe of the averaged star formation rate • Due to their very short main-sequence lifetimes the shape of the SFR can be reconstructed from the luminosity function of massive white dwarfs • To achieve these goals, we need R~5000 spectroscop ...
... • The white dwarf luminosity function of Gaia is a sensitive probe of the averaged star formation rate • Due to their very short main-sequence lifetimes the shape of the SFR can be reconstructed from the luminosity function of massive white dwarfs • To achieve these goals, we need R~5000 spectroscop ...
Slide 1
... a pulsar, tau = P/2(dP/dt) for the Crab Nebula is about 1400 years - and this was observed to explode in 1054. The continuous supply of high energy particles from the pulsar to the surrounding nebula explains the observed energy output levels from the nebula since the original explosion. The Crab pu ...
... a pulsar, tau = P/2(dP/dt) for the Crab Nebula is about 1400 years - and this was observed to explode in 1054. The continuous supply of high energy particles from the pulsar to the surrounding nebula explains the observed energy output levels from the nebula since the original explosion. The Crab pu ...
Energetic neutral atoms around HD 209458b
... meta-particle, and Vc is the cell volume. If Nm is different for different particles, we must sum all Nm instead of using Nc Nm . To avoid an operation count proportional to Nc2 , following Garcia (2000, p. 359), we do not directly compute the averages. Instead we estimate a maximum value of σvr , ( ...
... meta-particle, and Vc is the cell volume. If Nm is different for different particles, we must sum all Nm instead of using Nc Nm . To avoid an operation count proportional to Nc2 , following Garcia (2000, p. 359), we do not directly compute the averages. Instead we estimate a maximum value of σvr , ( ...
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.