An Improved Distance and Mass Estimate for Sgr A* from a Multistar
... the much deeper adaptive optics images and the vast improvement that has been made in the knowledge of the central black hole’s properties. We use constraints on a star’s orbit from the deep adaptive optics data to inform the search for the star in the earlier speckle years. As a pilot study for thi ...
... the much deeper adaptive optics images and the vast improvement that has been made in the knowledge of the central black hole’s properties. We use constraints on a star’s orbit from the deep adaptive optics data to inform the search for the star in the earlier speckle years. As a pilot study for thi ...
A Herschel/HIFI study of Water in Two Intermediate
... Stars are large, luminous, gravitationally bound spheres of hot gas. Their luminosity lights up the galaxy, providing much of the energy that illuminates the less luminous features such as large molecular clouds of gas. Studying other galaxies in the universe is also possible because of stars. Galax ...
... Stars are large, luminous, gravitationally bound spheres of hot gas. Their luminosity lights up the galaxy, providing much of the energy that illuminates the less luminous features such as large molecular clouds of gas. Studying other galaxies in the universe is also possible because of stars. Galax ...
MUFASA: The assembly of the red sequence
... forming red sequence elliptical galaxies may be more complex than canonically believed. Models that aim to explain massive galaxy formation must reproduce all these subtle facets of the observed galaxy population. Stringent constraints on models are already provided by the detailed observed properti ...
... forming red sequence elliptical galaxies may be more complex than canonically believed. Models that aim to explain massive galaxy formation must reproduce all these subtle facets of the observed galaxy population. Stringent constraints on models are already provided by the detailed observed properti ...
REVIEW Early star-forming galaxies and the reionization of the Universe
... The observed rest-frame ultraviolet luminosity density of star-forming galaxies, which are the expected sources of the photons that cause reionization, provides the cosmic star formation rate density, rSFR (Figure panel a: circles with 1-s.d. error bars40,41,62,86,87; grey points indicate the contri ...
... The observed rest-frame ultraviolet luminosity density of star-forming galaxies, which are the expected sources of the photons that cause reionization, provides the cosmic star formation rate density, rSFR (Figure panel a: circles with 1-s.d. error bars40,41,62,86,87; grey points indicate the contri ...
3011800000630
... the radius R in the disk corresponding to that effective temperature were listed. The last column gives the ratio of dissipation to irradiation powered disk fluxes at that radius. The total emission in each band is predominantly supplied by parts of the disk near the quoted radius, but of course the ...
... the radius R in the disk corresponding to that effective temperature were listed. The last column gives the ratio of dissipation to irradiation powered disk fluxes at that radius. The total emission in each band is predominantly supplied by parts of the disk near the quoted radius, but of course the ...
III Ionized Hydrogen (HII) Regions
... III Ionized Hydrogen (HII) Regions Ionized atomic Hydrogen regions, broadly termed “HII Regions”, are composed of gas ionized by photons with energies above the Hydrogen ionization energy of 13.6eV. These objects include “Classical HII Regions” ionized by hot O or B stars (or clusters of such stars) ...
... III Ionized Hydrogen (HII) Regions Ionized atomic Hydrogen regions, broadly termed “HII Regions”, are composed of gas ionized by photons with energies above the Hydrogen ionization energy of 13.6eV. These objects include “Classical HII Regions” ionized by hot O or B stars (or clusters of such stars) ...
Where stars are born: Javier Blasco-Herrera
... Distributor: Department of Astronomy, Stockholm University ...
... Distributor: Department of Astronomy, Stockholm University ...
Gravitational Waves from 3D MHD Core
... I performed an extensive series of more than 30 three-dimensional magnetohydrodynamical (MHD) core-collapse simulations. My models are based on a 15M progenitor stemming from stellar evolution calculations, an effective general relativistic potential and either the Lattimer-Swesty (with three possi ...
... I performed an extensive series of more than 30 three-dimensional magnetohydrodynamical (MHD) core-collapse simulations. My models are based on a 15M progenitor stemming from stellar evolution calculations, an effective general relativistic potential and either the Lattimer-Swesty (with three possi ...
Bondi Accretion onto a Luminous Object
... for a disk accretor. The thick solid curve is the accretion rate of “spherical” flow onto a disk source. The two solid lines are the accretion luminosities produced by the accretion processes for two different values of ṁB . The intersection point gives a steady canonical solution under a given par ...
... for a disk accretor. The thick solid curve is the accretion rate of “spherical” flow onto a disk source. The two solid lines are the accretion luminosities produced by the accretion processes for two different values of ṁB . The intersection point gives a steady canonical solution under a given par ...
An extended main-sequence turn-off in the Small
... present masses of these two SMC clusters differ by a factor of ∼4, the comparison between their colour–magnitude diagrams (CMDs) shows striking similarities, especially regarding the shape of their eMSTOs. The loci of main CMD features are so similar that they can be well described, in a first appro ...
... present masses of these two SMC clusters differ by a factor of ∼4, the comparison between their colour–magnitude diagrams (CMDs) shows striking similarities, especially regarding the shape of their eMSTOs. The loci of main CMD features are so similar that they can be well described, in a first appro ...
Modelling galaxy spectra in presence of interstellar dust – II. From
... In this paper, we present spectrophotometric models for galaxies of different morphological type whose spectral energy distributions (SEDs) take into account the effect of dust in absorbing ultraviolet–optical (UV–optical) light and re-emitting it in the infrared. The models contain three main compo ...
... In this paper, we present spectrophotometric models for galaxies of different morphological type whose spectral energy distributions (SEDs) take into account the effect of dust in absorbing ultraviolet–optical (UV–optical) light and re-emitting it in the infrared. The models contain three main compo ...
The X-ray/radio and UV luminosity expected from symbiotic systems
... owing to the existence of the CSM, the possibility of significant blueshifts for some absorption lines can be expected in the spectra of some SNe Ia, even though the true nature of the blueshift is not fully understood (Sternberg et al. 2014). Sternberg et al. (2011) checked the absorption propertie ...
... owing to the existence of the CSM, the possibility of significant blueshifts for some absorption lines can be expected in the spectra of some SNe Ia, even though the true nature of the blueshift is not fully understood (Sternberg et al. 2014). Sternberg et al. (2011) checked the absorption propertie ...
Annual Report 2012 - Max Planck Institute for Astrophysics
... instrumental activities carried out in other MaxPlanck institutes. From its inception the MPA has The Max-Planck-Institut für Astrophysik, called had an internationally-recognized numerical astrothe MPA for short, was founded in 1958 under the physics program that is unparalleled by any other direct ...
... instrumental activities carried out in other MaxPlanck institutes. From its inception the MPA has The Max-Planck-Institut für Astrophysik, called had an internationally-recognized numerical astrothe MPA for short, was founded in 1958 under the physics program that is unparalleled by any other direct ...
Understanding the Cool DA White Dwarf, G29-38
... surface nodes along a line of longitude. Most observed modes are ℓ=1, with a smattering of ℓ=2. There have been no reliable identifications of an ℓ=3 (or higher) mode in any white dwarf star. {Yℓm (θ, φ)} ...
... surface nodes along a line of longitude. Most observed modes are ℓ=1, with a smattering of ℓ=2. There have been no reliable identifications of an ℓ=3 (or higher) mode in any white dwarf star. {Yℓm (θ, φ)} ...
Universe of Motion - Reciprocal System of theory
... these laws and principles were put into the theories. To this vast amount of knowledge and pseudo-knowledge drawn from the common store, the theorist adds a few assumptions of his own that bear directly on the point at issue and, after subjecting the entire mass of material to his reasoning processe ...
... these laws and principles were put into the theories. To this vast amount of knowledge and pseudo-knowledge drawn from the common store, the theorist adds a few assumptions of his own that bear directly on the point at issue and, after subjecting the entire mass of material to his reasoning processe ...
Comparison between the luminosity functions of X
... The X-ray luminosity has been derived in the local Universe using the RXTE slew survey data (Sazonov & Revnivtsev 2004). The authors of this survey, construct a sample of 76 non-blazar AGN, with luminosity Lx > 1041 erg s−1 , most of them populating low redshifts z < 0.1. They derive the luminosity ...
... The X-ray luminosity has been derived in the local Universe using the RXTE slew survey data (Sazonov & Revnivtsev 2004). The authors of this survey, construct a sample of 76 non-blazar AGN, with luminosity Lx > 1041 erg s−1 , most of them populating low redshifts z < 0.1. They derive the luminosity ...
Stars and dust in the Galactic Center
... Binwise median and maximum three-dimensional velocity . . . . Binwise maximum of the minimum binding mass . . . . . . . . . Distance constraints from stars that are close to escaping . . . . Velocity histograms of our dynamics sample . . . . . . . . . . . Fits of the dispersion in the inner 25′′ by ...
... Binwise median and maximum three-dimensional velocity . . . . Binwise maximum of the minimum binding mass . . . . . . . . . Distance constraints from stars that are close to escaping . . . . Velocity histograms of our dynamics sample . . . . . . . . . . . Fits of the dispersion in the inner 25′′ by ...
Cool Subdwarf Investigations (CSI) I: New Thoughts for the Spectral
... stars (solid circles) having indices located near or in the main sequence regions in these plots have been manually checked to confirm that they are subdwarfs. Using the HR diagram in Figure 4, we confirm the low luminosities of our spectroscopically selected subdwarfs (V − Ks > 2.7) that have accur ...
... stars (solid circles) having indices located near or in the main sequence regions in these plots have been manually checked to confirm that they are subdwarfs. Using the HR diagram in Figure 4, we confirm the low luminosities of our spectroscopically selected subdwarfs (V − Ks > 2.7) that have accur ...
Whole Earth Telescope observations of BPM 37093: A
... Since 1960 most astronomers have agreed that cool white dwarfs must eventually crystallize (Kirzhnitz 1960; Abrikosov 1960; Salpeter 1961). The process theoretically begins when the electrostatic interaction between the ions becomes much larger than the thermal energy. This effect is based on such we ...
... Since 1960 most astronomers have agreed that cool white dwarfs must eventually crystallize (Kirzhnitz 1960; Abrikosov 1960; Salpeter 1961). The process theoretically begins when the electrostatic interaction between the ions becomes much larger than the thermal energy. This effect is based on such we ...
The Ionized Nebula surrounding the Red Supergiant W26 in
... Sher 25. The ring nebula around Sher 25 has a diameter of 0.4 pc and an outflow 0.5 pc in length (Brandner et al. 1997), slightly larger than the structures seen around W26. There is some uncertainty as to whether the nebula around Sher 25 was ejected during the star’s current BSG phase or a previou ...
... Sher 25. The ring nebula around Sher 25 has a diameter of 0.4 pc and an outflow 0.5 pc in length (Brandner et al. 1997), slightly larger than the structures seen around W26. There is some uncertainty as to whether the nebula around Sher 25 was ejected during the star’s current BSG phase or a previou ...
MOLECULAR OUTFLOWS AND A MID
... PAH emission features stimulated by UV radiation from the cluster. The subject of this paper is the dark filament in the top left which is forming early B stars. The mid-IR emission from the UC H ii region G34.4+0.23 is significantly less than that of G34.26, as expected due to the lower luminosity ...
... PAH emission features stimulated by UV radiation from the cluster. The subject of this paper is the dark filament in the top left which is forming early B stars. The mid-IR emission from the UC H ii region G34.4+0.23 is significantly less than that of G34.26, as expected due to the lower luminosity ...
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... by Krumholz et al. (2006), where Bondi accretion is assumed, with the Bondi velocity dispersion set either to the turbulent velocity dispersion or to the velocity dispersion due to vorticity. Models of accretion onto a star-forming core have been proposed to follow p = 1 (Myers 2000, Basu & Jones 20 ...
... by Krumholz et al. (2006), where Bondi accretion is assumed, with the Bondi velocity dispersion set either to the turbulent velocity dispersion or to the velocity dispersion due to vorticity. Models of accretion onto a star-forming core have been proposed to follow p = 1 (Myers 2000, Basu & Jones 20 ...
Systematic variation in the apparent burning area of thermonuclear
... due to the scattering of photons by the electrons in a neutron star atmosphere. From equation (3) we see that for a given source with fixed z, R 2∞ can change only if the colour factor f changes, and/or the actual burning region area (∝ R 2BB ) evolves, perhaps in combination with the change in the ...
... due to the scattering of photons by the electrons in a neutron star atmosphere. From equation (3) we see that for a given source with fixed z, R 2∞ can change only if the colour factor f changes, and/or the actual burning region area (∝ R 2BB ) evolves, perhaps in combination with the change in the ...
Presolar History Recorded in Extraterrestrial Materials
... isotopic systems. Single-grain analysis reveals the true extent of isotopic variation among these grains and has played an integral role in the identification of new presolar grain types. The first-generation secondary ion mass spectrometry (SIMS) instruments were indispensable to the study of stard ...
... isotopic systems. Single-grain analysis reveals the true extent of isotopic variation among these grains and has played an integral role in the identification of new presolar grain types. The first-generation secondary ion mass spectrometry (SIMS) instruments were indispensable to the study of stard ...
Asteroseismic Modelling of Solar-like Stars
... through nuclear fusion and emit it in the form of light. Furthermore, most of the elements that the Earth and all the living things are made up of have been produced in the stars. Scientists are in particular interested in understanding what is beyond apparent. However, all the information we have a ...
... through nuclear fusion and emit it in the form of light. Furthermore, most of the elements that the Earth and all the living things are made up of have been produced in the stars. Scientists are in particular interested in understanding what is beyond apparent. However, all the information we have a ...
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.