AAVSO: Epsilon Aurigae
... contributed observations of all eclipses since 1928. We hope that everyone can go and observe this object in 2009 -- since it's a naked-eye star, it will be within reach of all of our observers. At your next observing session, try making a visual estimate of epsilon Aurigae, regardless of whether yo ...
... contributed observations of all eclipses since 1928. We hope that everyone can go and observe this object in 2009 -- since it's a naked-eye star, it will be within reach of all of our observers. At your next observing session, try making a visual estimate of epsilon Aurigae, regardless of whether yo ...
are coronae of late-type stars made of solar-like structures? the x
... particular, this work shows that stellar coronae can be composed of X-ray–emitting structures similar to those present in the solar corona. To this end we use a large set of ROSAT PSPC observations of late-type stars of all spectral types and activity levels and a large set of solar X-ray data colle ...
... particular, this work shows that stellar coronae can be composed of X-ray–emitting structures similar to those present in the solar corona. To this end we use a large set of ROSAT PSPC observations of late-type stars of all spectral types and activity levels and a large set of solar X-ray data colle ...
outer-disk populations in ngc 7793: evidence for stellar
... A potentially better analog to NGC 7793 is the equivalent simulation generated to model NGC 300 in Gogarten et al. (2010). This galaxy is another member of the Sculptor Group with mass similar to NGC 7793, although the star formation history (SFH) of the system and the lack of a disk break indicate ...
... A potentially better analog to NGC 7793 is the equivalent simulation generated to model NGC 300 in Gogarten et al. (2010). This galaxy is another member of the Sculptor Group with mass similar to NGC 7793, although the star formation history (SFH) of the system and the lack of a disk break indicate ...
Angular momentum and the formation of stars and
... rotating magnetospheric region. More than 99% of the initial angular momentum of the gas from which each star forms must therefore be removed during the formation process. Where does this angular momentum go, and how is it transported? In standard models for isolated star formation (Shu et al 1987, ...
... rotating magnetospheric region. More than 99% of the initial angular momentum of the gas from which each star forms must therefore be removed during the formation process. Where does this angular momentum go, and how is it transported? In standard models for isolated star formation (Shu et al 1987, ...
PDF only - at www.arxiv.org.
... of the feedback process by which energy is transferred from the central massive black hole to the surrounding gas. The mechanism by which the filaments are stabilized against tidal shear and dissipation into the surrounding 4×107K gas has been unclear. Here we report new observations that resolve th ...
... of the feedback process by which energy is transferred from the central massive black hole to the surrounding gas. The mechanism by which the filaments are stabilized against tidal shear and dissipation into the surrounding 4×107K gas has been unclear. Here we report new observations that resolve th ...
Galactic Nebulae
... Dark Nebulae ----------Seen as dark cloud in front of stars/ nebulae Bright sources of IR emission - from dust ...
... Dark Nebulae ----------Seen as dark cloud in front of stars/ nebulae Bright sources of IR emission - from dust ...
star formation and galactic evolution
... stars, gas is ionized at a total rate of about 75 M yr−1 throughout our Galaxy. This is a far larger mass flux between different phases of the ISM than any that is thought to be associated with more energetic phenomena such as supernova heating; for example, estimates of the rate at which gas is cy ...
... stars, gas is ionized at a total rate of about 75 M yr−1 throughout our Galaxy. This is a far larger mass flux between different phases of the ISM than any that is thought to be associated with more energetic phenomena such as supernova heating; for example, estimates of the rate at which gas is cy ...
GRB EXPERIMENT
... • Note that the definition does not specify the magnetic field strength • To explain SGRs and AXPs, however, B must be greater than the quantum critical value 4.4 x 1013 G, where the energy between electron Landau levels equals their rest mass • Some AXPs and SGRs require B~1015 Gauss, so these magn ...
... • Note that the definition does not specify the magnetic field strength • To explain SGRs and AXPs, however, B must be greater than the quantum critical value 4.4 x 1013 G, where the energy between electron Landau levels equals their rest mass • Some AXPs and SGRs require B~1015 Gauss, so these magn ...
The HIRES science case
... conditions of the inner regions of the accretion disks and protoplanetary disks of young stellar objects, hence providing unprecedented constraints on the physics of star formation, jet launching mechanisms and planet formation. To achieve these goals we propose here that in the near-IR the instrume ...
... conditions of the inner regions of the accretion disks and protoplanetary disks of young stellar objects, hence providing unprecedented constraints on the physics of star formation, jet launching mechanisms and planet formation. To achieve these goals we propose here that in the near-IR the instrume ...
Galaxy Collisions, Gas Stripping and Star Formation in the Evolution
... I review gravitational and hydrodynamical processes during formation of clusters and evolution of galaxies. Early, at the advent of N-body computer simulations, the importance of tidal fields in galaxy encounters has been recognized. Orbits are crowded due to tides along spiral arms, where the star ...
... I review gravitational and hydrodynamical processes during formation of clusters and evolution of galaxies. Early, at the advent of N-body computer simulations, the importance of tidal fields in galaxy encounters has been recognized. Orbits are crowded due to tides along spiral arms, where the star ...
The two components of the evolved massive binary LZ Cephei
... Methods. We analyzed a set of high-resolution, high signal-to-noise ratio optical spectra obtained over the orbital period of the system to perform a spectroscopic disentangling and derive an orbital solution. We subsequently determine the stellar properties of each component by means of an analysis ...
... Methods. We analyzed a set of high-resolution, high signal-to-noise ratio optical spectra obtained over the orbital period of the system to perform a spectroscopic disentangling and derive an orbital solution. We subsequently determine the stellar properties of each component by means of an analysis ...
Part IV: Stars
... from the core to the photosphere. Computers let us calculate the Sun’s temperature, pressure, and density at any depth. We can check the models by comparing their predictions for the radius, surface temperature, and luminosity, as well as other observable parameters generated by studying helioseismo ...
... from the core to the photosphere. Computers let us calculate the Sun’s temperature, pressure, and density at any depth. We can check the models by comparing their predictions for the radius, surface temperature, and luminosity, as well as other observable parameters generated by studying helioseismo ...
Low frequency radio observations of gamma-ray binaries
... consistent model which explains the observations of high energy sources. High-Energy Astrophysics is the study of those astrophysical systems displaying X-ray or gamma-ray emission, but also those which emits neutrinos or cosmic rays. As the most energetic emission can not be explained by hot matter ...
... consistent model which explains the observations of high energy sources. High-Energy Astrophysics is the study of those astrophysical systems displaying X-ray or gamma-ray emission, but also those which emits neutrinos or cosmic rays. As the most energetic emission can not be explained by hot matter ...
Module3: Life of a Star
... companion star (two stars orbiting around a common centre of mass), the white dwarf will pull matter from the companion star onto its surface, until it becomes unstable and explodes as a supernova. Type Ia supernova can also be caused by two white dwarfs merging to the same end. Supernova Remnants N ...
... companion star (two stars orbiting around a common centre of mass), the white dwarf will pull matter from the companion star onto its surface, until it becomes unstable and explodes as a supernova. Type Ia supernova can also be caused by two white dwarfs merging to the same end. Supernova Remnants N ...
Stellar Evolution - Astrophysics
... stars are infinitely distant, the parallactic angle as it tained from the two sub-frames of Fig. 1 readily p sired angular measure. However, since the backgro in fact not infinitely distant, they themselves march (albeit smaller) parallactic motion, for which the t measurement must be corrected. If ...
... stars are infinitely distant, the parallactic angle as it tained from the two sub-frames of Fig. 1 readily p sired angular measure. However, since the backgro in fact not infinitely distant, they themselves march (albeit smaller) parallactic motion, for which the t measurement must be corrected. If ...
IAC_L2_thindisk
... the disk, e.g. via Jeans equation. Is there more matter in the disk that we can account for from census of visible objects ? The tracer sample must be in equilibrium so the stars need to be older than a few Gyr. The last few estimates have used K dwarfs and K giants - probably OK but they do include ...
... the disk, e.g. via Jeans equation. Is there more matter in the disk that we can account for from census of visible objects ? The tracer sample must be in equilibrium so the stars need to be older than a few Gyr. The last few estimates have used K dwarfs and K giants - probably OK but they do include ...
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.