Submm Observations of Massive Star Formation in the Giant
... Context. How massive stars (M>8 M ) form and how they accrete gas is still an open research field, but it is known that their influence on the interstellar medium (ISM) is immense. Star formation involves the gravitational collapse of gas from scales of giant molecular clouds (GMCs) down to dense h ...
... Context. How massive stars (M>8 M ) form and how they accrete gas is still an open research field, but it is known that their influence on the interstellar medium (ISM) is immense. Star formation involves the gravitational collapse of gas from scales of giant molecular clouds (GMCs) down to dense h ...
Polaris B, an optical companion of the Polaris (αUMi) system
... Polaris B (BD+88◦ 7; SAO 305) is the nearest optical companion to the Cepheid binary Polaris Ab (α UMi) system. Its visual magnitude of 8.60 mag, angular distance of 18 arcsec from Polaris, and spectral type of F3 V suggest that it is a physical main-sequence companion of α UMi (Fernie 1966; Turner ...
... Polaris B (BD+88◦ 7; SAO 305) is the nearest optical companion to the Cepheid binary Polaris Ab (α UMi) system. Its visual magnitude of 8.60 mag, angular distance of 18 arcsec from Polaris, and spectral type of F3 V suggest that it is a physical main-sequence companion of α UMi (Fernie 1966; Turner ...
astro-ph/9808039 PDF
... was the calibration standard. The corrected calibration of the GAFPIC data has been confirmed by comparison to another study that also uses HK11 as the calibration source (Mayya 1994). Also, the GAFPIC images have been refined by subtracting ghost images reflected from the Fabry-Perot blocking filte ...
... was the calibration standard. The corrected calibration of the GAFPIC data has been confirmed by comparison to another study that also uses HK11 as the calibration source (Mayya 1994). Also, the GAFPIC images have been refined by subtracting ghost images reflected from the Fabry-Perot blocking filte ...
The Binary Populations of Eight Globular Clusters in the Outer Halo
... We exploit three indexes provided by the adopted software and described in detail by Anderson et al. (2008) as diagnostics of photometric quality: the fraction of flux in the stellar aperture from its neighbours (o), the fractional residuals in the fit of the PSF to the pixel (q), and the rms of the ...
... We exploit three indexes provided by the adopted software and described in detail by Anderson et al. (2008) as diagnostics of photometric quality: the fraction of flux in the stellar aperture from its neighbours (o), the fractional residuals in the fit of the PSF to the pixel (q), and the rms of the ...
Read Claudia`s PhD thesis
... globular clusters in other galaxies can we confidently assume that the HB luminosity level will be the same for the Galactic RR Lyrae stars used in calibrating this relation and for the extragalactic RR Lyrae used to actually infer the distance. Our first target has been the Fornax dSph galaxy, one ...
... globular clusters in other galaxies can we confidently assume that the HB luminosity level will be the same for the Galactic RR Lyrae stars used in calibrating this relation and for the extragalactic RR Lyrae used to actually infer the distance. Our first target has been the Fornax dSph galaxy, one ...
Observation of the Crab pulsar wind nebula and microquasar Ph.D. Dissertation
... the Imaging Atmospheric Cherenkov Telescope (IACT) in the exploration of the Very High Energy (VHE) band. The last generation of IACTs, with the High Energy Stereoscopic System (HESS), Very Energetic Radiation Imaging Telescope Array System (VERITAS), and Major Atmospheric Gamma-ray Imaging Cherenko ...
... the Imaging Atmospheric Cherenkov Telescope (IACT) in the exploration of the Very High Energy (VHE) band. The last generation of IACTs, with the High Energy Stereoscopic System (HESS), Very Energetic Radiation Imaging Telescope Array System (VERITAS), and Major Atmospheric Gamma-ray Imaging Cherenko ...
AN EXPERT COMPUTER PROGRAM FOR CLASSIFYING STARS
... The MK Classification System, first devised by Morgan et al. (1943), classifies stars by direct comparison with MK standard stars. The most recent detailed discussion of the MK system is that of Gray & Corbally (2009); that reference also has an appendix with extensive lists of MK standard stars. Th ...
... The MK Classification System, first devised by Morgan et al. (1943), classifies stars by direct comparison with MK standard stars. The most recent detailed discussion of the MK system is that of Gray & Corbally (2009); that reference also has an appendix with extensive lists of MK standard stars. Th ...
galaxy formation and evolution - Yale Astronomy
... progressively larger ones, possibly in a hierarchical fashion; the galaxies that we now observe may then just represent the smallest structures that have survived as discrete units (Peebles 1974). The detailed way in which structure develops and galaxies form depends on the nature of the initial den ...
... progressively larger ones, possibly in a hierarchical fashion; the galaxies that we now observe may then just represent the smallest structures that have survived as discrete units (Peebles 1974). The detailed way in which structure develops and galaxies form depends on the nature of the initial den ...
Analysis of cool DO-type white dwarfs from the Sloan Digital Sky
... As a result of their fast evolutionary rate, there are only a few very hot H-deficient stars. A literature study revealed that there are currently only 46 known PG 1159 stars, 10 O(He) stars, and 52 DO WDs1,2 . The detection and analysis of new DO WDs improve their statistics and thus helps to under ...
... As a result of their fast evolutionary rate, there are only a few very hot H-deficient stars. A literature study revealed that there are currently only 46 known PG 1159 stars, 10 O(He) stars, and 52 DO WDs1,2 . The detection and analysis of new DO WDs improve their statistics and thus helps to under ...
Carnegie Observatories Astrophysics Series, Vol. 4:
... ultrasmall grains. As noted above, a large population of PAHs is required to account for the observed IR emission, and it is reasonable to suppose that these PAHs may be responsible for many of the DIBs. What is needed now is laboratory gas-phase absorption spectra for comparison with observed DIBs. ...
... ultrasmall grains. As noted above, a large population of PAHs is required to account for the observed IR emission, and it is reasonable to suppose that these PAHs may be responsible for many of the DIBs. What is needed now is laboratory gas-phase absorption spectra for comparison with observed DIBs. ...
THE COBE DIRBE POINT SOURCE CATALOG
... The first confusion flag is set when a second known infraredbright source is located within 0N5 of the target source. We used limits for the brightness of the companion of 25, 20, 20, 10, 30, 55, 320, and 765 Jy for 1.25–100 m, respectively. These are conservative limits, equal to the average per m ...
... The first confusion flag is set when a second known infraredbright source is located within 0N5 of the target source. We used limits for the brightness of the companion of 25, 20, 20, 10, 30, 55, 320, and 765 Jy for 1.25–100 m, respectively. These are conservative limits, equal to the average per m ...
Annual Report 2014 - Max Planck Institute for Astrophysics
... the directorship of Ludwig Biermann. It was estab- MPA has had an internationally-recognized numerlished as an offshoot of the Max-Planck-Institut für ical astrophysics program that was long unparalPhysik, which at that time had just moved from leled by any other institution of similar size. Göttinge ...
... the directorship of Ludwig Biermann. It was estab- MPA has had an internationally-recognized numerlished as an offshoot of the Max-Planck-Institut für ical astrophysics program that was long unparalPhysik, which at that time had just moved from leled by any other institution of similar size. Göttinge ...
Chapman
... making use of multi-wavelength data spanning from the radio to the X-ray • As opposed to traditional magnitude-limited surveys, down to specific flux limit, new results utilize several complementary selection techniques for finding high-z galaxies, selecting overlapping yet complementary populations ...
... making use of multi-wavelength data spanning from the radio to the X-ray • As opposed to traditional magnitude-limited surveys, down to specific flux limit, new results utilize several complementary selection techniques for finding high-z galaxies, selecting overlapping yet complementary populations ...
Envelope inflation in massive stars near the Eddington limit
... Massive stars, i.e. those stars with masses more than about 10 times that of the Sun, are important agents for the chemical and dynamical evolution of galaxies. Because of the steep mass-luminosity relation, massive stars are extremely luminous objects. Therefore, increasingly massive stars approach ...
... Massive stars, i.e. those stars with masses more than about 10 times that of the Sun, are important agents for the chemical and dynamical evolution of galaxies. Because of the steep mass-luminosity relation, massive stars are extremely luminous objects. Therefore, increasingly massive stars approach ...
Chap3-Astrometry
... refrences objects N, is a term dependent on k and the magnitude and distribution of reference stars. This yields to performance of ~100 μas for 10m class telescopes with very good seeing and t~600 s Narrow-field imagers on Palomar and VLT, including adaptive ...
... refrences objects N, is a term dependent on k and the magnitude and distribution of reference stars. This yields to performance of ~100 μas for 10m class telescopes with very good seeing and t~600 s Narrow-field imagers on Palomar and VLT, including adaptive ...
betelgeuse and the red supergiants
... Giant Branch (super-AGB) star it would end up as an electron-capture supernova or die a less spectacular death leaving behind an oxygen-neon-magnesium white dwarf possibly surrounded by a planetary nebula. Often, Betelgeuse is assigned a birth mass of 15 M⊙ , which would place it above the mass rang ...
... Giant Branch (super-AGB) star it would end up as an electron-capture supernova or die a less spectacular death leaving behind an oxygen-neon-magnesium white dwarf possibly surrounded by a planetary nebula. Often, Betelgeuse is assigned a birth mass of 15 M⊙ , which would place it above the mass rang ...
doctoral thesis (Dissertation)
... and UV spectroscopy and through detailed physical simulations. Spectroscopic X-ray data is reduced and presented for two targets: The CTTS V4046 Sgr was observed with Chandra for 100 ks, using a high-resolution grating spectrometer. The lightcurve contains one flare and the He-like triplets of Si xi ...
... and UV spectroscopy and through detailed physical simulations. Spectroscopic X-ray data is reduced and presented for two targets: The CTTS V4046 Sgr was observed with Chandra for 100 ks, using a high-resolution grating spectrometer. The lightcurve contains one flare and the He-like triplets of Si xi ...
Modelling galaxy spectra in presence of interstellar dust – II. From
... (SWIRE – Lonsdale et al. 2003) and the SIRTF Nearby Galaxies Survey (SINGS – Kennicutt et al. 2003). The IR data will increase even more with the coming ASTRO-F mission (Pearson et al. 2004) and the advent of the James Webb Space Telescope (JWST). Combined with other astronomical data bases, they pr ...
... (SWIRE – Lonsdale et al. 2003) and the SIRTF Nearby Galaxies Survey (SINGS – Kennicutt et al. 2003). The IR data will increase even more with the coming ASTRO-F mission (Pearson et al. 2004) and the advent of the James Webb Space Telescope (JWST). Combined with other astronomical data bases, they pr ...
PPT
... At lower temperatures, white dwarfs are expected to crystallize and phase separation of the main constituents of the core of a typical white dwarf, 12C and 16O, is expected to occur. This sequence of events is expected to introduce significant delays in the cooling times, but has not been proven ...
... At lower temperatures, white dwarfs are expected to crystallize and phase separation of the main constituents of the core of a typical white dwarf, 12C and 16O, is expected to occur. This sequence of events is expected to introduce significant delays in the cooling times, but has not been proven ...
Classical Be Stars: Rapidly Rotating B Stars with Viscous Keplerian
... population with likely a different mechanism responsible for the filling of the circumstellar environment (which may nevertheless be disk-shaped). Star with Emission Line Magnetospheres: Magnetic B stars do not typically show line emission, but depending on the field strength, wind, mass-loss and ro ...
... population with likely a different mechanism responsible for the filling of the circumstellar environment (which may nevertheless be disk-shaped). Star with Emission Line Magnetospheres: Magnetic B stars do not typically show line emission, but depending on the field strength, wind, mass-loss and ro ...
Origin and Evolution of the Abundance Gradient along the Milky
... gradient. As time goes on, star formation “migrates” to the outer disk, producing metals and flattening the abundance gradient there. However, the mechanisms mentioned above could work together. It is difficult to distinguish which one plays a more important role, or if the scenario may be different ...
... gradient. As time goes on, star formation “migrates” to the outer disk, producing metals and flattening the abundance gradient there. However, the mechanisms mentioned above could work together. It is difficult to distinguish which one plays a more important role, or if the scenario may be different ...
Galaxies at High Redshift Encyclopedia of Astronomy & Astrophysics eaa.iop.org Mauro Giavalisco
... high redshifts play a central role in cosmology because they provide insight into the epochs and the mechanisms of GALAXY FORMATION, if one can reach redshifts that are high enough to correspond to the cosmic epochs when galaxies were forming their first populations of stars and began to shine light ...
... high redshifts play a central role in cosmology because they provide insight into the epochs and the mechanisms of GALAXY FORMATION, if one can reach redshifts that are high enough to correspond to the cosmic epochs when galaxies were forming their first populations of stars and began to shine light ...
Galactic Evolution of Silicon Isotopes: Application to Presolar SiC
... Only neutron capture reactions are expected to modify the silicon isotopic composition in AGB stars. One expects s-processing in the helium shell, interspersed with dredgeups, to show monotonically evolving silicon isotopic ratios. A carbon star origin site for presolar SiC grains would almost be re ...
... Only neutron capture reactions are expected to modify the silicon isotopic composition in AGB stars. One expects s-processing in the helium shell, interspersed with dredgeups, to show monotonically evolving silicon isotopic ratios. A carbon star origin site for presolar SiC grains would almost be re ...
Planetary nebula
A planetary nebula, often abbreviated as PN or plural PNe, is a kind of emission nebula consisting of an expanding glowing shell of ionized gas ejected from old red giant stars late in their lives. The word ""nebula"" is Latin for mist or cloud and the term ""planetary nebula"" is a misnomer that originated in the 1780s with astronomer William Herschel because when viewed through his telescope, these objects appeared to him to resemble the rounded shapes of planets. Herschel's name for these objects was popularly adopted and has not been changed. They are a relatively short-lived phenomenon, lasting a few tens of thousands of years, compared to a typical stellar lifetime of several billion years.A mechanism for formation of most planetary nebulae is thought to be the following: at the end of the star's life, during the red giant phase, the outer layers of the star are expelled by strong stellar winds. Eventually, after most of the red giant's atmosphere is dissipated, the exposed hot, luminous core emits ultraviolet radiation to ionize the ejected outer layers of the star. Absorbed ultraviolet light energises the shell of nebulous gas around the central star, appearing as a bright coloured planetary nebula at several discrete visible wavelengths.Planetary nebulae may play a crucial role in the chemical evolution of the Milky Way, returning material to the interstellar medium from stars where elements, the products of nucleosynthesis (such as carbon, nitrogen, oxygen and neon), have been created. Planetary nebulae are also observed in more distant galaxies, yielding useful information about their chemical abundances.In recent years, Hubble Space Telescope images have revealed many planetary nebulae to have extremely complex and varied morphologies. About one-fifth are roughly spherical, but the majority are not spherically symmetric. The mechanisms which produce such a wide variety of shapes and features are not yet well understood, but binary central stars, stellar winds and magnetic fields may play a role.