Does feedback help or hinder star formation? The effect of
... (Górski et al. 2005). Each star particle has an ionising luminosity of 3 × 1046 ph/s/M⊙ (Schaerer 2003). This value assumes solar metallicity and a Salpeter initial mass function between 1 − 100 M⊙ . Within this range, the IMF gradient does not depend strongly on model choice, for example giving a ...
... (Górski et al. 2005). Each star particle has an ionising luminosity of 3 × 1046 ph/s/M⊙ (Schaerer 2003). This value assumes solar metallicity and a Salpeter initial mass function between 1 − 100 M⊙ . Within this range, the IMF gradient does not depend strongly on model choice, for example giving a ...
stochastic star formation and a (nearly) uniform stellar
... alone cannot reproduce the entire range of observed luminosity (cf. L09). In the fc = 1 model, simulated galaxies that lie at the lowest LHα for any given LFUV have an excess of older and massive clusters. This is because at low SFR, a massive cluster represents a significant event in the galaxy SFH ...
... alone cannot reproduce the entire range of observed luminosity (cf. L09). In the fc = 1 model, simulated galaxies that lie at the lowest LHα for any given LFUV have an excess of older and massive clusters. This is because at low SFR, a massive cluster represents a significant event in the galaxy SFH ...
disks surviving the radiation pressure of radio pulsars
... The radiation pressure of a radio pulsar does not necessarily disrupt a surrounding disk. The position of the inner radius of a thin disk around a neutron star, determined by the balance of stresses, can be estimated by comparing the electromagnetic energy density generated by the neutron star as a ...
... The radiation pressure of a radio pulsar does not necessarily disrupt a surrounding disk. The position of the inner radius of a thin disk around a neutron star, determined by the balance of stresses, can be estimated by comparing the electromagnetic energy density generated by the neutron star as a ...
University of Groningen Photo-ionization studies of nebulae
... of temperature, and the third panel shows the evolutionary rate in kelvin per year as function of temperature. In the second panel it is visible that the transition phase occurs at higher temperatures for larger core masses with the recipes described above. The evolutionary rate, mass loss rate and ...
... of temperature, and the third panel shows the evolutionary rate in kelvin per year as function of temperature. In the second panel it is visible that the transition phase occurs at higher temperatures for larger core masses with the recipes described above. The evolutionary rate, mass loss rate and ...
Direct Imaging discovery of a second planet candidate
... Methods. We report on photometric and spectroscopic high contrast observations with the Very Large Telescope, the Keck telescopes and the Calar Alto observatory that reveal a directly imaged planet candidate close to the young M3 star CVSO 30. Results. The JHK-band photometry of the newly identified ...
... Methods. We report on photometric and spectroscopic high contrast observations with the Very Large Telescope, the Keck telescopes and the Calar Alto observatory that reveal a directly imaged planet candidate close to the young M3 star CVSO 30. Results. The JHK-band photometry of the newly identified ...
Links Between Pulsation and Line-Driven Mass Loss in Massive Stars
... winds also often show modulation at periods comparable to the stellar rotation period. July 30, 2001 ...
... winds also often show modulation at periods comparable to the stellar rotation period. July 30, 2001 ...
Gamma-Ray Bursts
... The core collapses to a white dwarf, and the rest of the star explodes in a supernova explosion. The core collapses into a neutron star, and the rest of the star explodes in a supernova explosion. The core collapses into a white dwarf, and the rest of the star explodes to form a planetary nebula. Th ...
... The core collapses to a white dwarf, and the rest of the star explodes in a supernova explosion. The core collapses into a neutron star, and the rest of the star explodes in a supernova explosion. The core collapses into a white dwarf, and the rest of the star explodes to form a planetary nebula. Th ...
A Massive Galaxy in its Core Formation Phase Three Billion Years
... universe. This high column density of gas in conjunction with the abundance of metals implies28 a very high extinction: AV & 100 for a screen, and AV & 6 if the dust and the stars are mixed. The detection of rest-frame optical flux, and of Hα emission, are inconsistent with such high values. The dus ...
... universe. This high column density of gas in conjunction with the abundance of metals implies28 a very high extinction: AV & 100 for a screen, and AV & 6 if the dust and the stars are mixed. The detection of rest-frame optical flux, and of Hα emission, are inconsistent with such high values. The dus ...
Giant planet and brown dwarf formation
... the early accretion of planetesimals? What are the distinctive observational signatures of these different processes? From a broader point of view, major questions concerning the very identification of brown dwarfs and gaseous planets remain to be answered. Among which, non exhaustively: do the mass ...
... the early accretion of planetesimals? What are the distinctive observational signatures of these different processes? From a broader point of view, major questions concerning the very identification of brown dwarfs and gaseous planets remain to be answered. Among which, non exhaustively: do the mass ...
Near-uniform internal rotation of the main sequence γ Doradus
... 2013; Cantiello et al. 2014). All of this indicates that some physics is missing in models of angular momentum transport in stellar interiors. Kepler observations show that the problem already exists on the main sequence. Two asteroseismic studies of rotation in main-sequence A stars have yielded un ...
... 2013; Cantiello et al. 2014). All of this indicates that some physics is missing in models of angular momentum transport in stellar interiors. Kepler observations show that the problem already exists on the main sequence. Two asteroseismic studies of rotation in main-sequence A stars have yielded un ...
Str\" omgren uvby photometry of the peculiar globular cluster NGC
... given filter to a common (median) flux scale. The r.m.s. scatter of these median magnitude corrections between frames was ∼0.03 mag, which gives an estimate of the precision of our zeropoints and thereby of the accuracy of our photometry relative to the standard system. While both nights were report ...
... given filter to a common (median) flux scale. The r.m.s. scatter of these median magnitude corrections between frames was ∼0.03 mag, which gives an estimate of the precision of our zeropoints and thereby of the accuracy of our photometry relative to the standard system. While both nights were report ...
Stellar contents and star formation in the young open cluster Stock 8
... SFRs (such as ρ Oph, IC 348, Trapezium) although there is a large difference in stellar densities. On the other hand Hillenbrand (1997) found a few SFRs with unusual IMFs. The lack of strong evidence for IMF variations suggests that its fundamental form may be universal. Consequently, local conditio ...
... SFRs (such as ρ Oph, IC 348, Trapezium) although there is a large difference in stellar densities. On the other hand Hillenbrand (1997) found a few SFRs with unusual IMFs. The lack of strong evidence for IMF variations suggests that its fundamental form may be universal. Consequently, local conditio ...
Zhu Qualifier Solutions - University of Toronto Astronomy
... 4.15.3. How is a P Cygni feature produced? ...
... 4.15.3. How is a P Cygni feature produced? ...
Puzzling X-rays from the new colliding wind binary Wolf–Rayet 65
... occurs near periastron, when a greater fraction of the stellar winds collides and the higher pre-shock densities and the lower pre-shock velocities result in stronger radiative cooling. The eclipse occurs immediately after periastron passage when the companion of η Car swings behind the LBV star wit ...
... occurs near periastron, when a greater fraction of the stellar winds collides and the higher pre-shock densities and the lower pre-shock velocities result in stronger radiative cooling. The eclipse occurs immediately after periastron passage when the companion of η Car swings behind the LBV star wit ...
DOC - IVOA
... parameters of objects) or data (FITS files describing wavelengths and fluxes) for groups of like stars without making explicit searches by star name one at a time or by cross correlation of established catalogs. This is a common request to archive centers holding spectroscopic datasets. NASA’s Inter ...
... parameters of objects) or data (FITS files describing wavelengths and fluxes) for groups of like stars without making explicit searches by star name one at a time or by cross correlation of established catalogs. This is a common request to archive centers holding spectroscopic datasets. NASA’s Inter ...
pg. 271 - Cornell University
... nebula, after the electron density and temperature are determined. Although the extinction correction in the infrared is small, the lines have been corrected for extinction using C(H) ¼ 0:15 (Meatheringham & Dopita 1991; Dopita et al. 1993) and are given in the fourth column of Table 1. 3.1. Electr ...
... nebula, after the electron density and temperature are determined. Although the extinction correction in the infrared is small, the lines have been corrected for extinction using C(H) ¼ 0:15 (Meatheringham & Dopita 1991; Dopita et al. 1993) and are given in the fourth column of Table 1. 3.1. Electr ...
Origin and Evolution of Neutron Star Magnetic Fields - if
... Neutron stars with young, high-mass companions (“high-mass X-ray binaries” or HMXBs) tend to appear as X-ray pulsars, in which the accreted material is presumably channelled by the magnetic field onto the polar caps. In some cases, cyclotron features have been found in the X-ray spectrum, correspondi ...
... Neutron stars with young, high-mass companions (“high-mass X-ray binaries” or HMXBs) tend to appear as X-ray pulsars, in which the accreted material is presumably channelled by the magnetic field onto the polar caps. In some cases, cyclotron features have been found in the X-ray spectrum, correspondi ...
Sub-luminous type Ia supernovae from the mergers of equal
... diversity. Interestingly, a recent analysis of the spectral evolution of SN 2005bl10, which is representative of the 1991bg-like SNe Ia, showed that both iron group elements and silicon are present over a wide range of radii extending as close to the centre of the ejecta as is accessible observation ...
... diversity. Interestingly, a recent analysis of the spectral evolution of SN 2005bl10, which is representative of the 1991bg-like SNe Ia, showed that both iron group elements and silicon are present over a wide range of radii extending as close to the centre of the ejecta as is accessible observation ...
Indroduction
... star forming medium (Padoan et al., 1997), which is likely to vary with galaxy mass. In regard to the second alternative, it is worth recalling that the mean lifetime of a binary system (Type Ia progenitors) is 1 Gyr, and therefore the contamination by Type Ia supernov occurs later as compared to ...
... star forming medium (Padoan et al., 1997), which is likely to vary with galaxy mass. In regard to the second alternative, it is worth recalling that the mean lifetime of a binary system (Type Ia progenitors) is 1 Gyr, and therefore the contamination by Type Ia supernov occurs later as compared to ...
RUPRECHT 147: THE OLDEST NEARBY OPEN CLUSTER AS A
... structure. Galactic gravitational tidal forces are effective at disrupting most Galactic clusters on a timescale of a few hundred Myr (Soderblom 2010), so most clusters tend to be relatively young. This is fortunate for studies of early stellar evolution and massive stars: for such work, stellar ast ...
... structure. Galactic gravitational tidal forces are effective at disrupting most Galactic clusters on a timescale of a few hundred Myr (Soderblom 2010), so most clusters tend to be relatively young. This is fortunate for studies of early stellar evolution and massive stars: for such work, stellar ast ...
Evolution and Magnitudes of Candidate Planet Nine
... stellar irradiation without significant thermal inertia. Figure 2 shows the apparent magnitudes for various bands for the nominal case during one orbit around the Sun at a semimajor axis of 700 AU and an eccentricity of 0.6, as proposed by Batygin & Brown (2016). At a distance of 700 AU, the planet ...
... stellar irradiation without significant thermal inertia. Figure 2 shows the apparent magnitudes for various bands for the nominal case during one orbit around the Sun at a semimajor axis of 700 AU and an eccentricity of 0.6, as proposed by Batygin & Brown (2016). At a distance of 700 AU, the planet ...
M sun
... Pistol star: initial mass ~ 200 Msun (but too metal rich to collapse into a BH) R145 in 30 Dor: M sin3i = (140 +/- 37) Msun ...
... Pistol star: initial mass ~ 200 Msun (but too metal rich to collapse into a BH) R145 in 30 Dor: M sin3i = (140 +/- 37) Msun ...
S-process in extremely metal-poor, low-mass stars
... experience a PIE during the first one or two thermal pulses in the beginning of the thermally pulsating asymptotic giant branch (TP-AGB) phase. Similar to the occurrence of the PIE during the core He-flash, proton-rich material is dragged down into the He-burning zone during the development of a the ...
... experience a PIE during the first one or two thermal pulses in the beginning of the thermally pulsating asymptotic giant branch (TP-AGB) phase. Similar to the occurrence of the PIE during the core He-flash, proton-rich material is dragged down into the He-burning zone during the development of a the ...
Chemical abundances of metal-poor RR Lyrae stars in the Magellanic Clouds
... studies. For et al. (2011) investigated the properties of eleven nearby field RR Lyrae stars and obtained very precise abundances for several elements. For the α-elements, they found a mean overabundance of [α/Fe] = 0.5 dex. This lack of information about α-elements for LMC RR Lyrae stars and the la ...
... studies. For et al. (2011) investigated the properties of eleven nearby field RR Lyrae stars and obtained very precise abundances for several elements. For the α-elements, they found a mean overabundance of [α/Fe] = 0.5 dex. This lack of information about α-elements for LMC RR Lyrae stars and the la ...
Resultados del Concurso 2008A para Observaciones en
... Resumen: It is currently problematic to measure ages of Galactic globular cluters (GCs) over the full range of observed metallicities using near-infrared photometry alone, because models cannot reliably reproduce the observed morphology in near-IR color-magnitude diagrams (CMDs). While a handful of ...
... Resumen: It is currently problematic to measure ages of Galactic globular cluters (GCs) over the full range of observed metallicities using near-infrared photometry alone, because models cannot reliably reproduce the observed morphology in near-IR color-magnitude diagrams (CMDs). While a handful of ...
Main sequence
In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell. Stars on this band are known as main-sequence stars or ""dwarf"" stars.After a star has formed, it generates thermal energy in the dense core region through the nuclear fusion of hydrogen atoms into helium. During this stage of the star's lifetime, it is located along the main sequence at a position determined primarily by its mass, but also based upon its chemical composition and other factors. All main-sequence stars are in hydrostatic equilibrium, where outward thermal pressure from the hot core is balanced by the inward pressure of gravitational collapse from the overlying layers. The strong dependence of the rate of energy generation in the core on the temperature and pressure helps to sustain this balance. Energy generated at the core makes its way to the surface and is radiated away at the photosphere. The energy is carried by either radiation or convection, with the latter occurring in regions with steeper temperature gradients, higher opacity or both.The main sequence is sometimes divided into upper and lower parts, based on the dominant process that a star uses to generate energy. Stars below about 1.5 times the mass of the Sun (or 1.5 solar masses (M☉)) primarily fuse hydrogen atoms together in a series of stages to form helium, a sequence called the proton–proton chain. Above this mass, in the upper main sequence, the nuclear fusion process mainly uses atoms of carbon, nitrogen and oxygen as intermediaries in the CNO cycle that produces helium from hydrogen atoms. Main-sequence stars with more than two solar masses undergo convection in their core regions, which acts to stir up the newly created helium and maintain the proportion of fuel needed for fusion to occur. Below this mass, stars have cores that are entirely radiative with convective zones near the surface. With decreasing stellar mass, the proportion of the star forming a convective envelope steadily increases, whereas main-sequence stars below 0.4 M☉ undergo convection throughout their mass. When core convection does not occur, a helium-rich core develops surrounded by an outer layer of hydrogen.In general, the more massive a star is, the shorter its lifespan on the main sequence. After the hydrogen fuel at the core has been consumed, the star evolves away from the main sequence on the HR diagram. The behavior of a star now depends on its mass, with stars below 0.23 M☉ becoming white dwarfs directly, whereas stars with up to ten solar masses pass through a red giant stage. More massive stars can explode as a supernova, or collapse directly into a black hole.