The 8190-A sodium doublet in cataclysmic variables
... variations of instrumental response with wavelength and for largescale sensitivity variations by multiplying by a calibration spectrum produced from the FIGARO tables of the Oke & Gunn standards. There were no comparison stars on the same slit for any of our objects, so absolute fluxes are not avail ...
... variations of instrumental response with wavelength and for largescale sensitivity variations by multiplying by a calibration spectrum produced from the FIGARO tables of the Oke & Gunn standards. There were no comparison stars on the same slit for any of our objects, so absolute fluxes are not avail ...
Molecular cloud regulated star formation in galaxies
... in a star-forming galaxy. Since stars are known to form in molecular clouds, our method focuses on simple rules for cloud formation. The star formation recipe then simply converts the most massive of these clouds, ‘Giant Molecular Clouds’ (GMCs), into stars with an imposed efficiency taken from MW o ...
... in a star-forming galaxy. Since stars are known to form in molecular clouds, our method focuses on simple rules for cloud formation. The star formation recipe then simply converts the most massive of these clouds, ‘Giant Molecular Clouds’ (GMCs), into stars with an imposed efficiency taken from MW o ...
Neutron Stars – Cooling and Transport
... The first works on neutron star cooling and thermal emission (Stabler 1960; Tsuruta 1964; Chiu and Salpeter 1964; Morton 1964; Bahcall and Wolf 1965a,b) appeared at the epoch of the discoveries of X-ray sources outside the Solar System in the rocket and balloon experiments (Giacconi et al. 1962; Bow ...
... The first works on neutron star cooling and thermal emission (Stabler 1960; Tsuruta 1964; Chiu and Salpeter 1964; Morton 1964; Bahcall and Wolf 1965a,b) appeared at the epoch of the discoveries of X-ray sources outside the Solar System in the rocket and balloon experiments (Giacconi et al. 1962; Bow ...
EVIDENCE FOR IMF VARIATIONS WITH GALACTIC ENVIRONMENT
... Brown et al. (2012), we presented a preliminary analysis of the stellar populations in the first three galaxies for which data had been taken. We concluded that all stars in these galaxies were older than 11 Gyr and that star formation lasted less than 2 Gyr. Here we present a companion analysis of ...
... Brown et al. (2012), we presented a preliminary analysis of the stellar populations in the first three galaxies for which data had been taken. We concluded that all stars in these galaxies were older than 11 Gyr and that star formation lasted less than 2 Gyr. Here we present a companion analysis of ...
The density of very massive evolved galaxies to z≃ 1.7
... The density of massive early types to z 1.7 break of galaxies at z < 1.2. We find that, at the average redshift z max 1.55, the seven massive early types account for a co-moving density ρ = (5.5 ± 2) × 10−5 Mpc−3 over a volume of about 1.5 × 105 Mpc3 . Given the stellar masses of the seven e ...
... The density of massive early types to z 1.7 break of galaxies at z < 1.2. We find that, at the average redshift z max 1.55, the seven massive early types account for a co-moving density ρ = (5.5 ± 2) × 10−5 Mpc−3 over a volume of about 1.5 × 105 Mpc3 . Given the stellar masses of the seven e ...
on the absolute age of the metal-rich globular m71
... We investigated the absolute age of the Galactic globular cluster M71 (NGC 6838) using optical ground-based images (u¢ , g¢ , r ¢ , i¢ , z ¢) collected with the MegaCam camera at the Canada–France–Hawaii Telescope (CFHT). We performed a robust selection of field and cluster stars by applying a new me ...
... We investigated the absolute age of the Galactic globular cluster M71 (NGC 6838) using optical ground-based images (u¢ , g¢ , r ¢ , i¢ , z ¢) collected with the MegaCam camera at the Canada–France–Hawaii Telescope (CFHT). We performed a robust selection of field and cluster stars by applying a new me ...
Neutron Stars in Compact Binary Systems: From the equation of
... In the discussion of neutron star equation of state thermodynamics, n will refer to number density and to total energy density. The mass per baryon, mb = 1.66 × 10−27 kg, of the matter dispersed to infinity is used define a rest mass density ρ ∼ n. Nuclear density is taken to be ρnuc = 2.7 × 1014 ...
... In the discussion of neutron star equation of state thermodynamics, n will refer to number density and to total energy density. The mass per baryon, mb = 1.66 × 10−27 kg, of the matter dispersed to infinity is used define a rest mass density ρ ∼ n. Nuclear density is taken to be ρnuc = 2.7 × 1014 ...
Early structure formation from cosmic string loops Abstract
... Ref. [19] studied structure formation and reionization in this new string evolution scenario and found that the resulting bound on Gµ was competitive with the CMB and gravitational radiation bounds. In the present paper we shall reexamine early structure formation by cosmic strings and its effect on ...
... Ref. [19] studied structure formation and reionization in this new string evolution scenario and found that the resulting bound on Gµ was competitive with the CMB and gravitational radiation bounds. In the present paper we shall reexamine early structure formation by cosmic strings and its effect on ...
Formation of the First Galaxies: Theory and Simulations
... ambiguous (see e.g. Bromm & Yoshida 2011). Here we shall adopt the common view that a galaxy must be able to host ongoing star formation, even in the face of the radiative and mechanical feedback that accompanies the formation and evolution of stars. By this definition, the formation sites of the fi ...
... ambiguous (see e.g. Bromm & Yoshida 2011). Here we shall adopt the common view that a galaxy must be able to host ongoing star formation, even in the face of the radiative and mechanical feedback that accompanies the formation and evolution of stars. By this definition, the formation sites of the fi ...
betelgeuse and the red supergiants
... Because Betelgeuse is relatively nearby one might not have thought that its distance would be a matter of contention. Yet the distances, based on parallax measurements, vary between 150–250 pc, corresponding to 0.4 dex in luminosity. The stellar evolution models predict that stars with birth masses ...
... Because Betelgeuse is relatively nearby one might not have thought that its distance would be a matter of contention. Yet the distances, based on parallax measurements, vary between 150–250 pc, corresponding to 0.4 dex in luminosity. The stellar evolution models predict that stars with birth masses ...
A" Light," Centrally-Concentrated Milky Way Halo?
... to γ = 4.5 beyond 60 kpc. In the galactocentric radial range 5 to 40 kpc, Bell et al. (2008) estimated a slope γ between 2 and 4, broadly consistent with our results (see also Deason et al. 2011b; Sesar et al. 2011). The stellar velocity anisotropy profile, shown in the middle panel of Figure 2, imp ...
... to γ = 4.5 beyond 60 kpc. In the galactocentric radial range 5 to 40 kpc, Bell et al. (2008) estimated a slope γ between 2 and 4, broadly consistent with our results (see also Deason et al. 2011b; Sesar et al. 2011). The stellar velocity anisotropy profile, shown in the middle panel of Figure 2, imp ...
planetary construction zones in occultation: discovery of an
... 5 The author dereddened the UBV photometry for OGLE-LMCECL-17782 from Massey (2002, catalogued as M2002 #148104) using the Q-method, and finds that the primary is most likely a slightly evolved ∼B2 star with (B-V)o ≃ -0.23 and MV ≃ -3.7. However this calculation does not take into account the differ ...
... 5 The author dereddened the UBV photometry for OGLE-LMCECL-17782 from Massey (2002, catalogued as M2002 #148104) using the Q-method, and finds that the primary is most likely a slightly evolved ∼B2 star with (B-V)o ≃ -0.23 and MV ≃ -3.7. However this calculation does not take into account the differ ...
ACCELERATION DUE TO GRAVITY OF A RAPIDLY ROTATING
... The explosion will result in a supernova type II event where most of the original star mass will be blown away and the dense solid core will remain. The collapse will continue even to high density than that associated with a white dwarf. The neutrons will produce a degeneracy pressure that will stop ...
... The explosion will result in a supernova type II event where most of the original star mass will be blown away and the dense solid core will remain. The collapse will continue even to high density than that associated with a white dwarf. The neutrons will produce a degeneracy pressure that will stop ...
The Dynamics of White Dwarfs, Black Holes and Stellar Cusps
... relationship between the mass and kinematics of white dwarfs is demonstrated, whereby high- ...
... relationship between the mass and kinematics of white dwarfs is demonstrated, whereby high- ...
Catalogs of Hot White Dwarfs in the Milky Way from GALEX`s
... http://galex.stsci.edu , and as High-Level Science Products (http://archive.stsci.edu/hlsp/ , in the “Catalogs” section). Therefore, we provide here information on how they were constructed that will be relevant for potential users, as well as to others interested in constructing future versions of ...
... http://galex.stsci.edu , and as High-Level Science Products (http://archive.stsci.edu/hlsp/ , in the “Catalogs” section). Therefore, we provide here information on how they were constructed that will be relevant for potential users, as well as to others interested in constructing future versions of ...
White dwarf dynamical interactions and fast optical transients
... Ca-rich gap transients have timescales similar to fast/bright transients, but are an order of magnitude fainter at peak (L ∼ 1042 erg s−1 , or MV ∼ −16), and show strong nebular features from Ca in their late-time spectra (Filippenko et al. 2003; Perets et al. 2010; Kasliwal et al. 2012). Finally, t ...
... Ca-rich gap transients have timescales similar to fast/bright transients, but are an order of magnitude fainter at peak (L ∼ 1042 erg s−1 , or MV ∼ −16), and show strong nebular features from Ca in their late-time spectra (Filippenko et al. 2003; Perets et al. 2010; Kasliwal et al. 2012). Finally, t ...
High Resolution Chandra Spectroscopy of Gamma Cassiopeia (B0
... SRH98). Highly redshifted spectral lines in the UV (Smith & Robinson 1999) are indicative of high velocity plasmoids, with energies comparable to the X-ray flux and suggest the interaction of X-ray emitting volumes with a circumstellar structure, probably the dense disk of the Be star. There is indi ...
... SRH98). Highly redshifted spectral lines in the UV (Smith & Robinson 1999) are indicative of high velocity plasmoids, with energies comparable to the X-ray flux and suggest the interaction of X-ray emitting volumes with a circumstellar structure, probably the dense disk of the Be star. There is indi ...
CHARACTERIZING THE COOL KOIs. III. KOI 961: A SMALL STAR
... and not a giant based on the shallowness of the CO absorption band, and we reported an effective temperature of 3200 ± 50 K and an overall metallicity ([M/H]) of −0.33 ± 0.12 using the spectroscopic indices and calibrations of Rojas-Ayala et al. (2011, hereafter RA11). KOI 961 was the coolest M dwar ...
... and not a giant based on the shallowness of the CO absorption band, and we reported an effective temperature of 3200 ± 50 K and an overall metallicity ([M/H]) of −0.33 ± 0.12 using the spectroscopic indices and calibrations of Rojas-Ayala et al. (2011, hereafter RA11). KOI 961 was the coolest M dwar ...
The (galaxy-wide) IMF in giant elliptical galaxies: from top to bottom
... GCs (Kim et al. 2013) the fraction of metal-poor GCs with LMXBs is only about two times lower than for metal-rich GCs (Kim et al. 2009). As almost all galaxies host both types of GCs, this effect his further diluted in respect to the much larger impact expected of a very bottom-heavy IMF. Several st ...
... GCs (Kim et al. 2013) the fraction of metal-poor GCs with LMXBs is only about two times lower than for metal-rich GCs (Kim et al. 2009). As almost all galaxies host both types of GCs, this effect his further diluted in respect to the much larger impact expected of a very bottom-heavy IMF. Several st ...
Effects of neutron-star superconductivity on
... flux tubes. (In a possible central core pion condensate Dirac monopoles terminate single flux tubes. ) The other terminal of the pair can be a monopale of opposite magnetic polarity. In that case the huge fiux-tube tension af Eq. (7) will quickly (i.e., within seconds) pull the pole and antipole tog ...
... flux tubes. (In a possible central core pion condensate Dirac monopoles terminate single flux tubes. ) The other terminal of the pair can be a monopale of opposite magnetic polarity. In that case the huge fiux-tube tension af Eq. (7) will quickly (i.e., within seconds) pull the pole and antipole tog ...
New Evidence for Mass-Loss from δ Cephei from H i 21
... fraction of circumstellar material that is hidden by Galactic contamination within our band or that is present on angular scales too large to be detected by the VLA. It appears that the bulk of the circumstellar gas has originated directly from the star, although it may be augmented by material swep ...
... fraction of circumstellar material that is hidden by Galactic contamination within our band or that is present on angular scales too large to be detected by the VLA. It appears that the bulk of the circumstellar gas has originated directly from the star, although it may be augmented by material swep ...
U P C NIVERSITAT
... Because of their well known observational properties Type Ia, or thermonuclear, supernovae are used as standard candles, and have allowed the discovery of the accelerating expansion of the Universe. Yet, despite their importance, we still do not know exactly which stellar systems produce them. Howev ...
... Because of their well known observational properties Type Ia, or thermonuclear, supernovae are used as standard candles, and have allowed the discovery of the accelerating expansion of the Universe. Yet, despite their importance, we still do not know exactly which stellar systems produce them. Howev ...
Separating gas-giant and ice-giant planets by halting pebble accretion
... A core embedded in the disc can accrete a sizable fraction of this radial pebble flux, f ≈ 30% (Morbidelli & Nesvorny 2012, see also Appendix A). In this work, we use surface densities in pebbles comparable to MMSN estimates, unless mentioned otherwise. This approximation is supported by theoretical ...
... A core embedded in the disc can accrete a sizable fraction of this radial pebble flux, f ≈ 30% (Morbidelli & Nesvorny 2012, see also Appendix A). In this work, we use surface densities in pebbles comparable to MMSN estimates, unless mentioned otherwise. This approximation is supported by theoretical ...
arXiv 2011 Feroci
... or hyperons may appear. At even higher densities a phase transition to strange quark matter may also occur. This high-density/low-temperature region of the QCD phase diagram is inaccessible to terrestrial laboratories and can only be probed astrophysically, where the ultradense matter EOS manifests ...
... or hyperons may appear. At even higher densities a phase transition to strange quark matter may also occur. This high-density/low-temperature region of the QCD phase diagram is inaccessible to terrestrial laboratories and can only be probed astrophysically, where the ultradense matter EOS manifests ...
Lennard-Jones quark matter and massive quark stars
... that in the inert gas, and should be determined in the context of quark stars. The model of quark stars composed of the Lennard-Jones matter is much different from conventional models (e.g. MIT bag model) in which the ground state is of the Fermi gas. In the former case, the quark clusters are non-r ...
... that in the inert gas, and should be determined in the context of quark stars. The model of quark stars composed of the Lennard-Jones matter is much different from conventional models (e.g. MIT bag model) in which the ground state is of the Fermi gas. In the former case, the quark clusters are non-r ...
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.