The ROSAT galactic plane survey: ASTRONOMY AND
... a low galactic latitude region selected from the ROSAT all-sky survey. The test field is centered at l = 90◦ , b = 0◦ and has an area of 64.5 deg2 . A total of 128 soft X-ray sources are detected above a maximum likelihood of 8. Catalogue searches and optical follow-up observations show that in this ...
... a low galactic latitude region selected from the ROSAT all-sky survey. The test field is centered at l = 90◦ , b = 0◦ and has an area of 64.5 deg2 . A total of 128 soft X-ray sources are detected above a maximum likelihood of 8. Catalogue searches and optical follow-up observations show that in this ...
Herschel far-infrared observations of the Carina Nebula complex⋆
... Most stars in our Galaxy form in giant molecular clouds, as parts of rich stellar clusters or associations, containing highmass (M > 20 M ) stars. Recent investigations have shown that also our solar system formed close to massive stars, which had important influences on the early evolution of the ...
... Most stars in our Galaxy form in giant molecular clouds, as parts of rich stellar clusters or associations, containing highmass (M > 20 M ) stars. Recent investigations have shown that also our solar system formed close to massive stars, which had important influences on the early evolution of the ...
betelgeuse and the red supergiants
... it will end as a core-collapse supernova leaving a neutron star or black hole. But do we know that it is? If Betelgeuse were to be a lower-mass super-Asymptotic Giant Branch (super-AGB) star it would end up as an electron-capture supernova or die a less spectacular death leaving behind an oxygen-neo ...
... it will end as a core-collapse supernova leaving a neutron star or black hole. But do we know that it is? If Betelgeuse were to be a lower-mass super-Asymptotic Giant Branch (super-AGB) star it would end up as an electron-capture supernova or die a less spectacular death leaving behind an oxygen-neo ...
thesis
... and the study of circumstellar disks from which it is thought planets may be formed. The advent of optical/infrared interferometry allows us now to probe the inner parts of these protoplanetary disks, giving insights into their structure, dynamics, and evolution. In parallel to these developments, t ...
... and the study of circumstellar disks from which it is thought planets may be formed. The advent of optical/infrared interferometry allows us now to probe the inner parts of these protoplanetary disks, giving insights into their structure, dynamics, and evolution. In parallel to these developments, t ...
RADIO OBSERVATIONS RELATED TO STAR FORMATION P. G.
... procedure; we introduce the review of observations (Sect. II) by outlining a working hypothesis for the evolutionary sequence of Ο and Β stars. This sequence is based on radio and IR observations of the giant HII region W3 (reviewed by Mezger and Wink, 1974) and on model calculations of dust-filled ...
... procedure; we introduce the review of observations (Sect. II) by outlining a working hypothesis for the evolutionary sequence of Ο and Β stars. This sequence is based on radio and IR observations of the giant HII region W3 (reviewed by Mezger and Wink, 1974) and on model calculations of dust-filled ...
EXTREMELY EXTENDED DUST SHELLS AROUND EVOLVED
... from your spirit and courage. I would also like to thank my wife, Heather Shawver, and our beautiful children, Rosemary and Brianna , for making me see life with a new meaning of hope and prosperity. I also thank my long - term child-hood friend, Tholinhlanhla Henry Ngcobo for helping me during tryi ...
... from your spirit and courage. I would also like to thank my wife, Heather Shawver, and our beautiful children, Rosemary and Brianna , for making me see life with a new meaning of hope and prosperity. I also thank my long - term child-hood friend, Tholinhlanhla Henry Ngcobo for helping me during tryi ...
Global structure and kinematics of stellar haloes in cosmological
... spectrum). The value of σ8 is approximately 2-sigma higher than has been inferred from the most recent CMB data (Komatsu et al. 2009), which will affect the abundance of Milky Way-mass systems somewhat, but should not significantly affect their individual properties. The simulations were evolved fro ...
... spectrum). The value of σ8 is approximately 2-sigma higher than has been inferred from the most recent CMB data (Komatsu et al. 2009), which will affect the abundance of Milky Way-mass systems somewhat, but should not significantly affect their individual properties. The simulations were evolved fro ...
CENTRAL STARS OF PLANETARY NEBULAE IN THE LARGE
... post-AGB phase, and /or perhaps a Wolf-Rayet ([ W-R]) phase. This would increase the star’s mass-loss rate and thus slow its evolution during these periods. Such an effect would manifest itself in the form of different relative population ratios in galaxies of varying metallicities. These implicatio ...
... post-AGB phase, and /or perhaps a Wolf-Rayet ([ W-R]) phase. This would increase the star’s mass-loss rate and thus slow its evolution during these periods. Such an effect would manifest itself in the form of different relative population ratios in galaxies of varying metallicities. These implicatio ...
Spectroscopic Studies of Evolved Stars and Planetary Nebulae
... hyperfine structure have been fitted to constrain optical depths. The population diagram method was applied to determine the rotation temperatures of molecules which had multiple transitions available. Column densities have been calculated for all detected species and isotopic ratios measured where ...
... hyperfine structure have been fitted to constrain optical depths. The population diagram method was applied to determine the rotation temperatures of molecules which had multiple transitions available. Column densities have been calculated for all detected species and isotopic ratios measured where ...
Star Captures by Quasar Accretion Disks: A Possible Explanation of
... & Tan 2003), and hence unstable to form stars? Why is the black hole mass tightly related to the velocity dispersion of the stellar system around it, when the physical scales of these components are so vastly different? Another possibility for the growth of black holes is by the direct capture of st ...
... & Tan 2003), and hence unstable to form stars? Why is the black hole mass tightly related to the velocity dispersion of the stellar system around it, when the physical scales of these components are so vastly different? Another possibility for the growth of black holes is by the direct capture of st ...
RUPRECHT 147: THE OLDEST NEARBY OPEN CLUSTER AS A
... observatories and have identified over 100 members, including 5 blue stragglers, 11 red giants, and 5 double-lined spectroscopic binaries (SB2s). We estimate the cluster metallicity from spectroscopic analysis, using Spectroscopy Made Easy (SME), and find it to be [M/H] = +0.07 ± 0.03. We have obtai ...
... observatories and have identified over 100 members, including 5 blue stragglers, 11 red giants, and 5 double-lined spectroscopic binaries (SB2s). We estimate the cluster metallicity from spectroscopic analysis, using Spectroscopy Made Easy (SME), and find it to be [M/H] = +0.07 ± 0.03. We have obtai ...
Catalogs of Hot White Dwarfs in the Milky Way from GALEX`s
... phases, in which they shed much of their mass. The ejected material enriches the interstellar medium (ISM) with newly synthesized nuclear products (mainly He, C, N, and possibly O), to different extents, depending on the initial stellar mass and exact evolutionary path (e.g. Marigo 2001, Karakas 201 ...
... phases, in which they shed much of their mass. The ejected material enriches the interstellar medium (ISM) with newly synthesized nuclear products (mainly He, C, N, and possibly O), to different extents, depending on the initial stellar mass and exact evolutionary path (e.g. Marigo 2001, Karakas 201 ...
A FUSE Survey of Coronal Forbidden Lines in Late
... Because of our relatively poor knowledge of the rest wavelengths of these lines, the relatively weak signal of the coronal lines, and the moderate likelihood of coincidental blends with low-temperature lines, labeling spectral features located at wavelengths coincident with an expected coronal line ...
... Because of our relatively poor knowledge of the rest wavelengths of these lines, the relatively weak signal of the coronal lines, and the moderate likelihood of coincidental blends with low-temperature lines, labeling spectral features located at wavelengths coincident with an expected coronal line ...
EVIDENCE FOR IMF VARIATIONS WITH GALACTIC ENVIRONMENT
... are more metal-rich than the UFDs. At metallicities less than [Fe/H] < −1, HST studies of Galactic globular clusters probe the IMF down to main sequence masses between 0.2 − 0.7 M⊙ (Paust et al. 2010). However, dynamical evolution, such as mass segregation and evaporation, can significantly change t ...
... are more metal-rich than the UFDs. At metallicities less than [Fe/H] < −1, HST studies of Galactic globular clusters probe the IMF down to main sequence masses between 0.2 − 0.7 M⊙ (Paust et al. 2010). However, dynamical evolution, such as mass segregation and evaporation, can significantly change t ...
Infrared Observations of Interstellar Ices Adwin Boogert NASA Herschel Science Center
... Far less ices than gas phase species detected because ices can only be detected by absorption spectroscopy: weakest features (1%) represent column density 0.01*4 [cm-1]/1e-17 [cm/molecule]=4e15 cm-2, orders of magnitude higher than gas phase detections! ...
... Far less ices than gas phase species detected because ices can only be detected by absorption spectroscopy: weakest features (1%) represent column density 0.01*4 [cm-1]/1e-17 [cm/molecule]=4e15 cm-2, orders of magnitude higher than gas phase detections! ...
A SPECTROSCOPIC STUDY OF A LARGE SAMPLE OF WOLF-RAYET GALAXIES
... We analyze long-slit spectral observations of 39 Wolf-Rayet (WR) galaxies with heavy element mass fraction ranging over 2 orders of magnitude, from Z /50 to 2Z . Nearly all galaxies in our sample show broad WR emission in the blue region of the spectrum (the blue bump) consisting of an unresolved ...
... We analyze long-slit spectral observations of 39 Wolf-Rayet (WR) galaxies with heavy element mass fraction ranging over 2 orders of magnitude, from Z /50 to 2Z . Nearly all galaxies in our sample show broad WR emission in the blue region of the spectrum (the blue bump) consisting of an unresolved ...
View/Open - University of Hertfordshire
... The measurement of radial velocity has played a pivotal role in the analysis and understanding of the cosmos. It provides a signature of the motion of objects tracing the distribution of matter and gravitational potential. The discovery of an expanding universe by Hubble [1925] was made from radial ...
... The measurement of radial velocity has played a pivotal role in the analysis and understanding of the cosmos. It provides a signature of the motion of objects tracing the distribution of matter and gravitational potential. The discovery of an expanding universe by Hubble [1925] was made from radial ...
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 ...
SUPERNOVA REMNANT SHOCKS IN AN INHOMOGENEOUS
... (McKee and Ostriker 1977). Although fh is high in the local ISM, its value at a typical point in the galactic disk remains controversial (Cox 1987). It is quite likely that fh depends on both the nature of the galaxy and the location within it. In principle, observations of SNRs could provide the me ...
... (McKee and Ostriker 1977). Although fh is high in the local ISM, its value at a typical point in the galactic disk remains controversial (Cox 1987). It is quite likely that fh depends on both the nature of the galaxy and the location within it. In principle, observations of SNRs could provide the me ...
Masses, Radii, and Equation of State of Neutron Stars
... We now know precise masses for ∼ 35 neutron stars spanning the range from 1.17 to 2.0 M⊙ and can pin down the radii of more than a dozen to the 9.9−11.2 km range. The combination of the heaviest known neutron star mass with the existing radius measurements already places significant constraints on t ...
... We now know precise masses for ∼ 35 neutron stars spanning the range from 1.17 to 2.0 M⊙ and can pin down the radii of more than a dozen to the 9.9−11.2 km range. The combination of the heaviest known neutron star mass with the existing radius measurements already places significant constraints on t ...
Formation of low-mass helium white dwarfs
... Astronomy is as old as mankind although the concepts tremendously evolved and changed with time. The last 100 years represents a huge step forward in scientific and technological development. For astronomy, the availability of more telescopes, bigger telescopes, space missions and ever increasing co ...
... Astronomy is as old as mankind although the concepts tremendously evolved and changed with time. The last 100 years represents a huge step forward in scientific and technological development. For astronomy, the availability of more telescopes, bigger telescopes, space missions and ever increasing co ...
New Evidence for Mass-Loss from δ Cephei from H i 21
... δ Cephei. The nebula has a head-tail morphology, consistent with circumstellar ejecta shaped by the interaction between a stellar wind and the interstellar medium (ISM). We directly measure a mass of circumstellar atomic hydrogen MHI ≈ 0.07 M⊙ , although the total H i mass may be larger, depending o ...
... δ Cephei. The nebula has a head-tail morphology, consistent with circumstellar ejecta shaped by the interaction between a stellar wind and the interstellar medium (ISM). We directly measure a mass of circumstellar atomic hydrogen MHI ≈ 0.07 M⊙ , although the total H i mass may be larger, depending o ...
Dust in Protoplanetary Disks: Properties and Evolution
... T Tauri stars (TTS) and brown dwarfs (BDs). On the theoretical side, there is a revived effort in modeling grain processing in disks (via coalescence, sedimentation, fragmentation, annealing, etc.) and its relation with the chemical and dynamical evolution of the gas. Although it is still very diffi ...
... T Tauri stars (TTS) and brown dwarfs (BDs). On the theoretical side, there is a revived effort in modeling grain processing in disks (via coalescence, sedimentation, fragmentation, annealing, etc.) and its relation with the chemical and dynamical evolution of the gas. Although it is still very diffi ...
Munshi_washington_0250E_12611
... stars. Middle Panel: SFHs for the bulges of the 3 galaxies not shown in this manuscript. Note that like h986 shown in Figure 3, the bulges form early in the galaxy’s history. Bottom Panel: SFHs for the disks of the 3 galaxies not shown in this manuscript. As with the bulges, these galaxies also foll ...
... stars. Middle Panel: SFHs for the bulges of the 3 galaxies not shown in this manuscript. Note that like h986 shown in Figure 3, the bulges form early in the galaxy’s history. Bottom Panel: SFHs for the disks of the 3 galaxies not shown in this manuscript. As with the bulges, these galaxies also foll ...
banff04
... Mout ~ 0.1 Mcore0.8 (derived from 1.2 mm dust emission) Dust emission increases with protostar age. (see also Sarceno et al. 1996, Chandler & Richer 2000, Richer et al. 2000) ...
... Mout ~ 0.1 Mcore0.8 (derived from 1.2 mm dust emission) Dust emission increases with protostar age. (see also Sarceno et al. 1996, Chandler & Richer 2000, Richer et al. 2000) ...
Nucleosynthesis
Nucleosynthesis is the process that creates new atomic nuclei from pre-existing nucleons, primarily protons and neutrons. The first nuclei were formed about three minutes after the Big Bang, through the process called Big Bang nucleosynthesis. It was then that hydrogen and helium formed to become the content of the first stars, and this primeval process is responsible for the present hydrogen/helium ratio of the cosmos.With the formation of stars, heavier nuclei were created from hydrogen and helium by stellar nucleosynthesis, a process that continues today. Some of these elements, particularly those lighter than iron, continue to be delivered to the interstellar medium when low mass stars eject their outer envelope before they collapse to form white dwarfs. The remains of their ejected mass form the planetary nebulae observable throughout our galaxy.Supernova nucleosynthesis within exploding stars by fusing carbon and oxygen is responsible for the abundances of elements between magnesium (atomic number 12) and nickel (atomic number 28). Supernova nucleosynthesis is also thought to be responsible for the creation of rarer elements heavier than iron and nickel, in the last few seconds of a type II supernova event. The synthesis of these heavier elements absorbs energy (endothermic) as they are created, from the energy produced during the supernova explosion. Some of those elements are created from the absorption of multiple neutrons (the R process) in the period of a few seconds during the explosion. The elements formed in supernovas include the heaviest elements known, such as the long-lived elements uranium and thorium.Cosmic ray spallation, caused when cosmic rays impact the interstellar medium and fragment larger atomic species, is a significant source of the lighter nuclei, particularly 3He, 9Be and 10,11B, that are not created by stellar nucleosynthesis.In addition to the fusion processes responsible for the growing abundances of elements in the universe, a few minor natural processes continue to produce very small numbers of new nuclides on Earth. These nuclides contribute little to their abundances, but may account for the presence of specific new nuclei. These nuclides are produced via radiogenesis (decay) of long-lived, heavy, primordial radionuclides such as uranium and thorium. Cosmic ray bombardment of elements on Earth also contribute to the presence of rare, short-lived atomic species called cosmogenic nuclides.