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Jaká kritéria jsou vhodná ke klasifikaci hvězd horní části hlavní
... Spectroscopy today is a highly developed method of studying electromagnetic radiation and stands as method bringing a vast amount of information about distant objects to us. Product of a spectroscopic measurement is called a spectrum and it is essentially a function of distribution of radiation resp ...
... Spectroscopy today is a highly developed method of studying electromagnetic radiation and stands as method bringing a vast amount of information about distant objects to us. Product of a spectroscopic measurement is called a spectrum and it is essentially a function of distribution of radiation resp ...
Chemical Composition of Selected Metal Poor Stars
... by GalaCtic chemical evolution (chemical enrichment history of our galaxy). Theories of Big Bang nucleosynthesis suggest that, it was mainly hydrogen, helium and little amount of elements upto boron which were synthesized primordially. Other metals (elements heavier than lithium) were formed from th ...
... by GalaCtic chemical evolution (chemical enrichment history of our galaxy). Theories of Big Bang nucleosynthesis suggest that, it was mainly hydrogen, helium and little amount of elements upto boron which were synthesized primordially. Other metals (elements heavier than lithium) were formed from th ...
Numerical Star-Formation Studies-
... The most massive stars are very bright, they allow us to reach out to the far ends of the universe. For example, the most distant galaxies in the Hubble Ultra Deep Field are all characterized by vigorous high-mass star formation. Understanding the origin of stars, at present and at early times, ther ...
... The most massive stars are very bright, they allow us to reach out to the far ends of the universe. For example, the most distant galaxies in the Hubble Ultra Deep Field are all characterized by vigorous high-mass star formation. Understanding the origin of stars, at present and at early times, ther ...
An Atlas of Stellar Spectra
... and, in the case of the stars of earlier class, parallaxes from interstellar line intensities and from the effects of galactic rotation. Throughout the discussion emphasis will be laid on the “normal” stars. A number of peculiar objects are noted; but the main aim of the investigation has been to ma ...
... and, in the case of the stars of earlier class, parallaxes from interstellar line intensities and from the effects of galactic rotation. Throughout the discussion emphasis will be laid on the “normal” stars. A number of peculiar objects are noted; but the main aim of the investigation has been to ma ...
as a PDF - Research Database
... B[e] star. The mass-loss rates were measured through modelling of the spectral energy distributions. We thus obtain the massloss rate formula log Ṁ = −5.65 + 1.05 log(L/10 000 L ) − 6.3 log(T eff /3500 K), valid for dust-enshrouded red supergiants and oxygen-rich AGB stars. Despite the low metallic ...
... B[e] star. The mass-loss rates were measured through modelling of the spectral energy distributions. We thus obtain the massloss rate formula log Ṁ = −5.65 + 1.05 log(L/10 000 L ) − 6.3 log(T eff /3500 K), valid for dust-enshrouded red supergiants and oxygen-rich AGB stars. Despite the low metallic ...
X-ray Binaries in Nearby Galaxies - CIERA
... to host LMXBs than Blue Clusters? Maccarone, Kundu, & Zepf 2004: Z-dependence of Irradiation-Induced Winds Ivanova 2005: Z-dependence of Magnetic Braking A.M. Loss In Blue, Metal-poor GCs MS donors w/ 0.85-1.25Mo have no outer convective zone ---> no MB ---> harder to start MT Even if MT starts, NS- ...
... to host LMXBs than Blue Clusters? Maccarone, Kundu, & Zepf 2004: Z-dependence of Irradiation-Induced Winds Ivanova 2005: Z-dependence of Magnetic Braking A.M. Loss In Blue, Metal-poor GCs MS donors w/ 0.85-1.25Mo have no outer convective zone ---> no MB ---> harder to start MT Even if MT starts, NS- ...
arXiv:1305.3647v1 [astro-ph.IM] 15 May 2013 - IRiS
... the first fruitful PRO-AM collaborations [29]. However, by the end of the 19th century, a gap started to open between professional and amateur astronomers due to the progressive use of spectroscopy in the field of astrophysics, which required bigger and much more expensive telescopes and instrumenta ...
... the first fruitful PRO-AM collaborations [29]. However, by the end of the 19th century, a gap started to open between professional and amateur astronomers due to the progressive use of spectroscopy in the field of astrophysics, which required bigger and much more expensive telescopes and instrumenta ...
THE FORMATION OF URANUS AND NEPTUNE IN SOLID
... are taken from Dodson-Robinson et al. (2009) and are based on a detailed chemical inventory of 211 gas and ice species. To allow for the time needed to build the 1M⊕ seed core and the planetesimals, we adopt a 0.15 Myr offset between the initial formation of the solar nebula and the beginning of pla ...
... are taken from Dodson-Robinson et al. (2009) and are based on a detailed chemical inventory of 211 gas and ice species. To allow for the time needed to build the 1M⊕ seed core and the planetesimals, we adopt a 0.15 Myr offset between the initial formation of the solar nebula and the beginning of pla ...
Radiation pressure from massive star clusters as a launching
... gas is more dilute at large distance, the clouds are less subject to destruction if they do eventually encounter hot gas. Therefore, unlike wind driven clouds, radiatively driven clouds can survive to distances ∼ 50 kpc, and potentially give rise to the metal absorbers seen in quasar spectra. We ide ...
... gas is more dilute at large distance, the clouds are less subject to destruction if they do eventually encounter hot gas. Therefore, unlike wind driven clouds, radiatively driven clouds can survive to distances ∼ 50 kpc, and potentially give rise to the metal absorbers seen in quasar spectra. We ide ...
Planet transit and stellar granulation detection with interferometry
... Context. Stellar activity and, in particular, convection-related surface structures, potentially cause bias in planet detection and characterisation. In the latter, interferometry can help disentangle the signal of the transiting planet. Aims. We used realistic three-dimensional (3D) radiative hydro ...
... Context. Stellar activity and, in particular, convection-related surface structures, potentially cause bias in planet detection and characterisation. In the latter, interferometry can help disentangle the signal of the transiting planet. Aims. We used realistic three-dimensional (3D) radiative hydro ...
The Spitzer/GLIMPSE Surveys - UW-Madison Astronomy
... as green in false color images consisting of IRAC 3.6 μm (blue), 4.5 μm (green), and 8.0 μm (red) bands. Enhanced emission at 4.5 μm is believed to be due to shocked H2 ðv ¼ 0 0Þ S(9, 10, 11) lines and/or COðv ¼ 1 0Þ bandheads, all of which fall within the IRAC 4.5 μm band. Soon after their dete ...
... as green in false color images consisting of IRAC 3.6 μm (blue), 4.5 μm (green), and 8.0 μm (red) bands. Enhanced emission at 4.5 μm is believed to be due to shocked H2 ðv ¼ 0 0Þ S(9, 10, 11) lines and/or COðv ¼ 1 0Þ bandheads, all of which fall within the IRAC 4.5 μm band. Soon after their dete ...
Sun, Stars and Planets Part 1: The Sun: its structure and energy
... The stellar material is an ionised gas or plasma, and is assumed to be an ideal gas. Because of the high T in stars all but the most tightly bound electrons are separated from the atoms. This allows a greater compression of stellar material without deviation from the perfect gas law because a nuclea ...
... The stellar material is an ionised gas or plasma, and is assumed to be an ideal gas. Because of the high T in stars all but the most tightly bound electrons are separated from the atoms. This allows a greater compression of stellar material without deviation from the perfect gas law because a nuclea ...
The Morphology of Galaxy Clusters
... Morphological classification of galaxy clusters is based mainly on the 2D distribution of galaxies, primarily from the Palomar Sky Survey. Classification schemes of galaxy clusters take into consideration several of their properties: shape, richness, lumpiness, Hubble mix, dominant galaxy types, etc ...
... Morphological classification of galaxy clusters is based mainly on the 2D distribution of galaxies, primarily from the Palomar Sky Survey. Classification schemes of galaxy clusters take into consideration several of their properties: shape, richness, lumpiness, Hubble mix, dominant galaxy types, etc ...
Stellar dust production and composition in the Magellanic Clouds F. Kemper
... in the ISO spectroscopy, and found that, while the spectra all show amorphous silicates, some of them also show the spectral signature of Al2 O3 (alumina). The relative strength of the alumina signature to the spectrum decreases with increasing mass-loss rate, suggestive of a covering of the alumina ...
... in the ISO spectroscopy, and found that, while the spectra all show amorphous silicates, some of them also show the spectral signature of Al2 O3 (alumina). The relative strength of the alumina signature to the spectrum decreases with increasing mass-loss rate, suggestive of a covering of the alumina ...
Galaxies over the Latter Half of Cosmic Time
... Galaxies over the Latter Half of Cosmic Time Marc Davis and Sandra M. Faber Galaxies are the basic systems of the universe. Like diamonds strewn across the sky, their tiny points of light mark the cosmic landscape. They reveal its organization into superclusters of thousands of galaxies, which bord ...
... Galaxies over the Latter Half of Cosmic Time Marc Davis and Sandra M. Faber Galaxies are the basic systems of the universe. Like diamonds strewn across the sky, their tiny points of light mark the cosmic landscape. They reveal its organization into superclusters of thousands of galaxies, which bord ...
On the role of the WNH phase in the evolution of very massive stars
... WC stars because they have not yet shed their H envelopes, and that they may eventually become H-poor WR stars. In that case WNH stars must be at a significantly earlier evolutionary stage, which is consistent with the fact that they are preferentially seen in massive clusters within giant H ii regi ...
... WC stars because they have not yet shed their H envelopes, and that they may eventually become H-poor WR stars. In that case WNH stars must be at a significantly earlier evolutionary stage, which is consistent with the fact that they are preferentially seen in massive clusters within giant H ii regi ...
Modeling the chemical evolution of the Galaxy halo
... their chemical abundances revealed the existence of two distinct halo populations with a systematic difference in [α/Fe], [Cu/Fe], [Zn/Fe] and [Ba/Y], but not in [Mn/Fe], at a given metallicity (Nissen & Schuster 2010, 2011, and references therein; see also Ishigaki et al. 2012). A dual distribution ...
... their chemical abundances revealed the existence of two distinct halo populations with a systematic difference in [α/Fe], [Cu/Fe], [Zn/Fe] and [Ba/Y], but not in [Mn/Fe], at a given metallicity (Nissen & Schuster 2010, 2011, and references therein; see also Ishigaki et al. 2012). A dual distribution ...
How Massive Single Stars End Their Life - TigerPrints
... M, low-metallicity stars form black holes directly, while at higher metallicities, black holes of smaller mass are produced by fallback until, ultimately, only neutron stars are made. Winds are assumed to be stronger in higher mass stars, so the metallicity at which these transitions occur decrease ...
... M, low-metallicity stars form black holes directly, while at higher metallicities, black holes of smaller mass are produced by fallback until, ultimately, only neutron stars are made. Winds are assumed to be stronger in higher mass stars, so the metallicity at which these transitions occur decrease ...
Sowing the Seeds of Asymmetry Jet-like Outflows in pPNe and AGB
... PN shapes/shaping: Primary Physical Processes (2) dense waists seen in PPNe, PNe likely form during the late AGB phase. From a study of a small sample, Huggins (2007) infers that waists and lobes formed nearly simultaneously, with waists forming a bit earlier (expansion timescales~few 100 to 1000 ...
... PN shapes/shaping: Primary Physical Processes (2) dense waists seen in PPNe, PNe likely form during the late AGB phase. From a study of a small sample, Huggins (2007) infers that waists and lobes formed nearly simultaneously, with waists forming a bit earlier (expansion timescales~few 100 to 1000 ...
The white dwarf binary pathways survey – I. A sample of FGK stars
... SN Ia spectra (Branch et al. 1995). Moreover, there is both theoretical and observational evidence for a large population of close double white dwarf binaries (Yungelson et al. 1994; Nelemans & Tout 2005; Napiwotzki et al. 2001). However, there is some uncertainty as to whether the merger leads to a ...
... SN Ia spectra (Branch et al. 1995). Moreover, there is both theoretical and observational evidence for a large population of close double white dwarf binaries (Yungelson et al. 1994; Nelemans & Tout 2005; Napiwotzki et al. 2001). However, there is some uncertainty as to whether the merger leads to a ...
arXiv:1604.01613v2 [astro-ph.SR] 23 Aug 2016
... SN Ia spectra (Branch et al. 1995). Moreover, there is both theoretical and observational evidence for a large population of close double white dwarf binaries (Yungelson et al. 1994; Nelemans & Tout 2005; Napiwotzki et al. 2001). However, there is some uncertainty as to whether the merger leads to a ...
... SN Ia spectra (Branch et al. 1995). Moreover, there is both theoretical and observational evidence for a large population of close double white dwarf binaries (Yungelson et al. 1994; Nelemans & Tout 2005; Napiwotzki et al. 2001). However, there is some uncertainty as to whether the merger leads to a ...
Analysis of white dwarfs with strange-matter cores
... 3. Modifications of the WD EOS We have made a systematic study of all correction terms to the white-dwarf equation of ...
... 3. Modifications of the WD EOS We have made a systematic study of all correction terms to the white-dwarf equation of ...
The extinction map of the OMC-1 molecular cloud behind the Orion
... obtained for the HST Treasury Program to discard 73 double stars and 166 extended objects, either background galaxies or proplyds (Ricci et al. 2008). Moreover, by looking at the JHKS color-color diagram for the subsample of stars with available J magnitude, we find 61 “field” stars well compatible ...
... obtained for the HST Treasury Program to discard 73 double stars and 166 extended objects, either background galaxies or proplyds (Ricci et al. 2008). Moreover, by looking at the JHKS color-color diagram for the subsample of stars with available J magnitude, we find 61 “field” stars well compatible ...
L171 COULD BLACK HOLE X-RAY BINARIES BE DETECTED IN
... high probability of detecting a BH XRB, since DC p 1 would correspond to X-ray emission being “on” throughout its lifetime, even though the BH may go through several companions. In all three cases of GC properties considered above, we find interaction timescales much shorter than typical GC ages (ⲏ1 ...
... high probability of detecting a BH XRB, since DC p 1 would correspond to X-ray emission being “on” throughout its lifetime, even though the BH may go through several companions. In all three cases of GC properties considered above, we find interaction timescales much shorter than typical GC ages (ⲏ1 ...
Confronting predictions of the galaxy stellar mass function with
... MassiveBlack. For MassiveBlack-II we instead used = 0.725 and m = 0.275 (according to WMAP7). Catalogues of galaxies are made from the simulation outputs by first using a friends-of-friends groupfinder and then applying the SUBFIND algorithm (Springel 2001) to find gravitationally bound subhaloe ...
... MassiveBlack. For MassiveBlack-II we instead used = 0.725 and m = 0.275 (according to WMAP7). Catalogues of galaxies are made from the simulation outputs by first using a friends-of-friends groupfinder and then applying the SUBFIND algorithm (Springel 2001) to find gravitationally bound subhaloe ...
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.