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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 ...
Oscillation Modes of Strange Quark Stars with a Strangelet Crust
... function of stellar mass for fixed B (by changing central density), one should note that the Bag “constant” is really an effective parameter of the model, and not an actual physical quantity. We therefore keep the value of quark mass fixed at 100 MeV and hold the central density constant, but vary t ...
... function of stellar mass for fixed B (by changing central density), one should note that the Bag “constant” is really an effective parameter of the model, and not an actual physical quantity. We therefore keep the value of quark mass fixed at 100 MeV and hold the central density constant, but vary t ...
The Universe
... based on the Big Bang theory. About 300,000 years after this event, atoms of hydrogen and helium began to form, in an event called recombination. Nearly all the hydrogen was neutral (non-ionized) and readily absorbed light, and no stars had yet formed. As a result this period has been called the "Da ...
... based on the Big Bang theory. About 300,000 years after this event, atoms of hydrogen and helium began to form, in an event called recombination. Nearly all the hydrogen was neutral (non-ionized) and readily absorbed light, and no stars had yet formed. As a result this period has been called the "Da ...
The Universe
... based on the Big Bang theory. About 300,000 years after this event, atoms of hydrogen and helium began to form, in an event called recombination. Nearly all the hydrogen was neutral (non-ionized) and readily absorbed light, and no stars had yet formed. As a result this period has been called the "Da ...
... based on the Big Bang theory. About 300,000 years after this event, atoms of hydrogen and helium began to form, in an event called recombination. Nearly all the hydrogen was neutral (non-ionized) and readily absorbed light, and no stars had yet formed. As a result this period has been called the "Da ...
Progenitors and Hydrodynamics of Type II and lb Supernovae
... ilar to that accompanying iron core collapse in larger stars, but with some observational distinctions. First, the density gradient at the edge of the ONeMg core is very steep. Little 56 Ni will be produced. Mayle & Wilson (1988) calculate ~0.002 M 0 of 56 Ni for a model of this sort. Also the envel ...
... ilar to that accompanying iron core collapse in larger stars, but with some observational distinctions. First, the density gradient at the edge of the ONeMg core is very steep. Little 56 Ni will be produced. Mayle & Wilson (1988) calculate ~0.002 M 0 of 56 Ni for a model of this sort. Also the envel ...
Star Formation: Chemistry as a Probe of Embedded Protostars
... The PACS spectrometer on Herschel had access to nearly all CO lines from J = 13–12 up to 49–48 (Poglitsch et al. 2010). The three key programs DIGIT, HOPS, and WISH combined to observe the CO ladder in more than 50 low-mass embedded protostars (van Kempen et al. 2010a,b; Visser et al. 2012; Herczeg ...
... The PACS spectrometer on Herschel had access to nearly all CO lines from J = 13–12 up to 49–48 (Poglitsch et al. 2010). The three key programs DIGIT, HOPS, and WISH combined to observe the CO ladder in more than 50 low-mass embedded protostars (van Kempen et al. 2010a,b; Visser et al. 2012; Herczeg ...
The structure of the compact planetary nebulae Cn 3-1 and M 3
... Although the mass-ejection processes involved in the formation of PNe are still poorly known, the observations suggest that a large fraction of the observed structures result from or are related to mass ejections which occur in a relatively short time interval between the end of the AGB phase and th ...
... Although the mass-ejection processes involved in the formation of PNe are still poorly known, the observations suggest that a large fraction of the observed structures result from or are related to mass ejections which occur in a relatively short time interval between the end of the AGB phase and th ...
Evolution of supermassive stars as a pathway to black hole formation
... Supermassive stars, with masses & 106 M⊙ , are possible progenitors of supermassive black holes in galactic nuclei. Because of their short nuclear burning timescales, such objects can be formed only when matter is able to accumulate at a rate exceeding ∼ 1M⊙ yr−1 . Here we revisit the structure and ...
... Supermassive stars, with masses & 106 M⊙ , are possible progenitors of supermassive black holes in galactic nuclei. Because of their short nuclear burning timescales, such objects can be formed only when matter is able to accumulate at a rate exceeding ∼ 1M⊙ yr−1 . Here we revisit the structure and ...
Empirical properties of Very Massive Stars
... strong winds which produce emission lines in the spectra: these objects are WolfRayet stars. The strong mass loss of WR stars peels them off, unravelling deep layers of chemically enriched material. WN stars correspond to objects showing the products of hydrogen burning (dominated by nitrogen), whil ...
... strong winds which produce emission lines in the spectra: these objects are WolfRayet stars. The strong mass loss of WR stars peels them off, unravelling deep layers of chemically enriched material. WN stars correspond to objects showing the products of hydrogen burning (dominated by nitrogen), whil ...
Quantitative evidence of an intrinsic luminosity spread in the Orion
... (1993) for effective temperatures larger than 8000 K, NextGen model atmospheres (Hauschildt et al. 1999) for 5000 ≤ T ≤ 8000 K, and AMES-MT 2000 models (Allard et al. 2000) for T ≤ 5000, all for solar metallicity in accordance with Da Rio et al. (2010a). Da Rio et al. (2010a) show that the colors of ...
... (1993) for effective temperatures larger than 8000 K, NextGen model atmospheres (Hauschildt et al. 1999) for 5000 ≤ T ≤ 8000 K, and AMES-MT 2000 models (Allard et al. 2000) for T ≤ 5000, all for solar metallicity in accordance with Da Rio et al. (2010a). Da Rio et al. (2010a) show that the colors of ...
Super and massive AGB stars-IV. Final fates
... The lowest mass stars that ignite carbon do so in the outermost layers of the core then abort further carbon burning (Fig. 1), leading to the creation of a class of hybrid WDs that we refer to as CO(Ne)s. In these stars the CO core is surrounded by a shell of carbon burnt material ∼ 0.1−0.4 M⊙ thick ...
... The lowest mass stars that ignite carbon do so in the outermost layers of the core then abort further carbon burning (Fig. 1), leading to the creation of a class of hybrid WDs that we refer to as CO(Ne)s. In these stars the CO core is surrounded by a shell of carbon burnt material ∼ 0.1−0.4 M⊙ thick ...
Period Changes of Delta Scuti Stars and Stellar Evolution
... For the radial pulsators of Pop. I, the observations indicate (1/P) dP/dt values around 10−7 year−1 with equal distribution between period increases and decreases. The evolutionary models, on the other hand, predict that the vast majority should show increasing periods. This increase should be a fac ...
... For the radial pulsators of Pop. I, the observations indicate (1/P) dP/dt values around 10−7 year−1 with equal distribution between period increases and decreases. The evolutionary models, on the other hand, predict that the vast majority should show increasing periods. This increase should be a fac ...
Simulations for Multi-Object Spectrograph Planet Surveys
... which dramatically increases (normally by at least an order of magnitude) the number of stars which are accessible to the particular survey. Also, a few of the groups have now been monitoring stars for a lengthy period of time such that they are able to detect planets with orbits larger than 5 AU. ...
... which dramatically increases (normally by at least an order of magnitude) the number of stars which are accessible to the particular survey. Also, a few of the groups have now been monitoring stars for a lengthy period of time such that they are able to detect planets with orbits larger than 5 AU. ...
Magnetars origin and progenitors with enhanced rotation'
... Magnetars origin and progenitors with enhanced rotation S.B. Popov, M.E. Prokhorov (Sternberg Astronomical Institute) ...
... Magnetars origin and progenitors with enhanced rotation S.B. Popov, M.E. Prokhorov (Sternberg Astronomical Institute) ...
A CCD Search for Variable Stars of Spectral Type B in the Northern
... the strength of these results, Hill (1967) classified the star as a β Cep variable. However, Delgado et al. (1992), from 42 uvby observations obtained on two nights, concluded that NGC 2169-2 was constant in light. Our 3270 differential V magnitudes of NGC 2169-2, computed with NGC 216911 and 15 as ...
... the strength of these results, Hill (1967) classified the star as a β Cep variable. However, Delgado et al. (1992), from 42 uvby observations obtained on two nights, concluded that NGC 2169-2 was constant in light. Our 3270 differential V magnitudes of NGC 2169-2, computed with NGC 216911 and 15 as ...
The extended structure of the dwarf irregular galaxy Sagittarius⋆⋆⋆
... 2014, hereafter Papers I and II, respectively), we demonstrated that the outer structures of these galaxies can be traced down to extremely low surface brightness (SB) levels (µV ' 30 mag/arcsec2 ) with star counts from very deep photometry obtained with state of the art wide-field cameras on 8 m cl ...
... 2014, hereafter Papers I and II, respectively), we demonstrated that the outer structures of these galaxies can be traced down to extremely low surface brightness (SB) levels (µV ' 30 mag/arcsec2 ) with star counts from very deep photometry obtained with state of the art wide-field cameras on 8 m cl ...
"The Pulsar Menagerie" (pdf file)
... or biweekly monitoring. That’s hard work.” –R.I. Radio Telescope finds pulsars in bunches. ...
... or biweekly monitoring. That’s hard work.” –R.I. Radio Telescope finds pulsars in bunches. ...
Stellar evolution models for Z = 0.0001 to 0.03
... There is a definite need for quantitatively reliable results of stellar evolution in other fields of astrophysics. In galactic astrophysics, stars are more than just one constituent of a galaxy. The stellar population interacts with the interstellar matter in various ways. The combined radiation fie ...
... There is a definite need for quantitatively reliable results of stellar evolution in other fields of astrophysics. In galactic astrophysics, stars are more than just one constituent of a galaxy. The stellar population interacts with the interstellar matter in various ways. The combined radiation fie ...
Stellar evolution models for Z = 0.0001 to 0.03
... There is a definite need for quantitatively reliable results of stellar evolution in other fields of astrophysics. In galactic astrophysics, stars are more than just one constituent of a galaxy. The stellar population interacts with the interstellar matter in various ways. The combined radiation fie ...
... There is a definite need for quantitatively reliable results of stellar evolution in other fields of astrophysics. In galactic astrophysics, stars are more than just one constituent of a galaxy. The stellar population interacts with the interstellar matter in various ways. The combined radiation fie ...
Abstracts - Space Telescope Science Institute
... Cluster formation and disruption, the role of the galactic host environment revealed by HST Less than 30 years ago the launch of the HST established a new field of research focus on young star clusters (YSCs). Galactic and extragalactic star-forming regions show that the vast majority of stars are f ...
... Cluster formation and disruption, the role of the galactic host environment revealed by HST Less than 30 years ago the launch of the HST established a new field of research focus on young star clusters (YSCs). Galactic and extragalactic star-forming regions show that the vast majority of stars are f ...
Modeling non-thermal emission from stellar bow shocks
... wether the bow shocks they form can also be a source of high energy photons in our galaxy. In particular, we study the bow shock formed by a supergiant star during the transition from blue to red using the star Betelgeuse as a test of our computations. The power available in the acceleration region ...
... wether the bow shocks they form can also be a source of high energy photons in our galaxy. In particular, we study the bow shock formed by a supergiant star during the transition from blue to red using the star Betelgeuse as a test of our computations. The power available in the acceleration region ...
Metallicity and Planet Formation: Models
... All planet formation theorists agree that terrestrial planets form by the collisional accumulation of solids composed of heavy elements in the inner regions of protoplanetary disks (e.g., Wetherill 1996). This process begins with the sedimentation of dust grains to the disk midplane and their growth ...
... All planet formation theorists agree that terrestrial planets form by the collisional accumulation of solids composed of heavy elements in the inner regions of protoplanetary disks (e.g., Wetherill 1996). This process begins with the sedimentation of dust grains to the disk midplane and their growth ...
I Introduction to the Interstellar Medium
... The first observational evidence that there was a general ISM that pervaded the space between the stars came from photographic spectroscopy of spectroscopic binary stars early in the 20th century. It was noticed that in addition to the relatively broad absorption lines associated with the atmosphere ...
... The first observational evidence that there was a general ISM that pervaded the space between the stars came from photographic spectroscopy of spectroscopic binary stars early in the 20th century. It was noticed that in addition to the relatively broad absorption lines associated with the atmosphere ...
ppt - Serbian Virtual Observatory
... - a common characteristic in the early evolution of all red dwarf stars. Belonging: - to the population of young stellar clusters and associations. Flare-like activity: some Wolf-Rayet stars, stars of B and A spectral types, RS Cvn system, some members of Algol and W UMa systems, FK Com stars and ev ...
... - a common characteristic in the early evolution of all red dwarf stars. Belonging: - to the population of young stellar clusters and associations. Flare-like activity: some Wolf-Rayet stars, stars of B and A spectral types, RS Cvn system, some members of Algol and W UMa systems, FK Com stars and ev ...
Wroclaw_VanGrootel
... can differ by orders of magnitude, especially in hot stars with radiative envelopes (such as sdB stars) The traditional observations only deals with surface layers Asteroseismology offers the unique opportunity to test the synchronization ...
... can differ by orders of magnitude, especially in hot stars with radiative envelopes (such as sdB stars) The traditional observations only deals with surface layers Asteroseismology offers the unique opportunity to test the synchronization ...
Planetary nebula
![](https://commons.wikimedia.org/wiki/Special:FilePath/NGC6543.jpg?width=300)
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.