The Layout of the Night Sky - Peterborough Astronomical Society
... same circle. Because of Earth’s tilt, the Sun appears highest in the sky relative to the celestial equator when the Earth is at one position in its orbit. This happens on or about June 21, and we call this the summer solstice (in the northern hemisphere). When the Earth is at the opposition side of ...
... same circle. Because of Earth’s tilt, the Sun appears highest in the sky relative to the celestial equator when the Earth is at one position in its orbit. This happens on or about June 21, and we call this the summer solstice (in the northern hemisphere). When the Earth is at the opposition side of ...
The Milky Way - Faculty Web Pages
... The first step to understanding our universe is noticing that the stars are not uniformly distributed across the sky. There are certain areas of the sky that have more stars than others. Let's see if we can see where that part of the sky is located. Start Stellarium. Turn off the Atmosphere and Fog. ...
... The first step to understanding our universe is noticing that the stars are not uniformly distributed across the sky. There are certain areas of the sky that have more stars than others. Let's see if we can see where that part of the sky is located. Start Stellarium. Turn off the Atmosphere and Fog. ...
FIRST DETECTION OF KRYPTON AND XENON IN A WHITE DWARF
... discussed that these overabundances might be ascribed to diffusion processes and to s-process nucleosynthesis in the AGB phase of the previous evolution. They also pointed out that this phenomenon is obviously restricted to DO WDs. This can be understood when considering that their immediate progeni ...
... discussed that these overabundances might be ascribed to diffusion processes and to s-process nucleosynthesis in the AGB phase of the previous evolution. They also pointed out that this phenomenon is obviously restricted to DO WDs. This can be understood when considering that their immediate progeni ...
here
... – where Sν is the flux density, κν is the mass absorption coefficient [e.g. Hildebrand 1983] – Fits typically invoke a spectral index for the opacity, and one or two temperature components, – can have significant optical depths at λ < 60µm and may have to consider non-thermal contributions from v ...
... – where Sν is the flux density, κν is the mass absorption coefficient [e.g. Hildebrand 1983] – Fits typically invoke a spectral index for the opacity, and one or two temperature components, – can have significant optical depths at λ < 60µm and may have to consider non-thermal contributions from v ...
The Evryscope: the first full-sky gigapixel-scale telescope Nicholas Law
... Asteroids around white dwarfs Confirmation of long-period TESS single-transit detections ...
... Asteroids around white dwarfs Confirmation of long-period TESS single-transit detections ...
Chapter 5 - Leiden Observatory
... We present an update to the software package SeBa [Portegies Zwart & Verbunt, 1996; Nelemans et al., 2001c] for fast stellar and binary evolution computations. Stars are evolved from the zero-age main sequence (ZAMS) until remnant formation and beyond. Stars are parametrised by mass, radius, luminos ...
... We present an update to the software package SeBa [Portegies Zwart & Verbunt, 1996; Nelemans et al., 2001c] for fast stellar and binary evolution computations. Stars are evolved from the zero-age main sequence (ZAMS) until remnant formation and beyond. Stars are parametrised by mass, radius, luminos ...
Galactic chemical evolution of heavy elements: from Barium to
... & Parthasaraty 1983; Gilroy et al. 1988) and a theoretical point of view (Truran 1981), only recently the observational data have grown sufficiently in number and precision to allow a direct comparison with theoretical predictions (see McWilliam 1995 for a review). In order to reconstruct the evolut ...
... & Parthasaraty 1983; Gilroy et al. 1988) and a theoretical point of view (Truran 1981), only recently the observational data have grown sufficiently in number and precision to allow a direct comparison with theoretical predictions (see McWilliam 1995 for a review). In order to reconstruct the evolut ...
Spectroscopic Binaries - Thüringer Landessternwarte Tautenburg
... SBs requires to disentangle the effects due to orbital motion • The eclipse phases in EBs can be used to screen the surface of the eclipsed star spectroscopically for the structure of its surface velocity field (e.g. pulsation) or to determine the stellar parameters (rotation, RME). ...
... SBs requires to disentangle the effects due to orbital motion • The eclipse phases in EBs can be used to screen the surface of the eclipsed star spectroscopically for the structure of its surface velocity field (e.g. pulsation) or to determine the stellar parameters (rotation, RME). ...
Draft paper (submitted to MNRAS)
... characteristic mass, corresponding to that of a halo with virial temperature ∼ 104 K at zreion (∼ 1.2 × 108 M⊙ for zreion = 6). Halos that have grown substantially more massive than this characteristic mass by zreion are affected little (Thoul & Weinberg 1996; Katz et al. 1996; Navarro & Steinmetz 1 ...
... characteristic mass, corresponding to that of a halo with virial temperature ∼ 104 K at zreion (∼ 1.2 × 108 M⊙ for zreion = 6). Halos that have grown substantially more massive than this characteristic mass by zreion are affected little (Thoul & Weinberg 1996; Katz et al. 1996; Navarro & Steinmetz 1 ...
stellar rotation in m35: mass–period relations, spin
... Here, a popular explanation for coeval rapid and slow rotators originates from the work of Koenigl (1991) and Edwards et al. (1993) on interactions between T Tauri stars and their circumstellar disks. “Magnetic disk-locking” was introduced to provide a means to brake the spin-up of the central star ...
... Here, a popular explanation for coeval rapid and slow rotators originates from the work of Koenigl (1991) and Edwards et al. (1993) on interactions between T Tauri stars and their circumstellar disks. “Magnetic disk-locking” was introduced to provide a means to brake the spin-up of the central star ...
Cataclysmic Variables
... of the components within these binaries. In disk CVs, the accretion disk was shown to be a dominant source of UV light, especially during an outburst. The delay between the start of the outburst in optical vs UV light led to increased understanding of the way the outburst proceeds through the disk. ...
... of the components within these binaries. In disk CVs, the accretion disk was shown to be a dominant source of UV light, especially during an outburst. The delay between the start of the outburst in optical vs UV light led to increased understanding of the way the outburst proceeds through the disk. ...
Pulsars as Astrophysical Laboratories for Nuclear and Particle Physics
... A collection of equations of state computed for several of these models is shown in Fig. 2. Mass–radius relationships of neutron stars based on these EoS are shown in Figs. 4 and 5. Strange star sequences are shown in these figures too. The strange star sequences shown in Fig. 5 show the impact of u ...
... A collection of equations of state computed for several of these models is shown in Fig. 2. Mass–radius relationships of neutron stars based on these EoS are shown in Figs. 4 and 5. Strange star sequences are shown in these figures too. The strange star sequences shown in Fig. 5 show the impact of u ...
The first gravitational-wave source from the isolated evolution of two
... subsequent binary black hole gravitational-wave events. Our models imply that these events form in an environment where the metallicity is less than 10 per cent of solar; have initial masses of 40–100 M⊙ ; and interact through mass transfer and a common envelope phase. Their progenitors likely form ...
... subsequent binary black hole gravitational-wave events. Our models imply that these events form in an environment where the metallicity is less than 10 per cent of solar; have initial masses of 40–100 M⊙ ; and interact through mass transfer and a common envelope phase. Their progenitors likely form ...
Validation of the frequency modulation technique applied to the
... (Beck et al. 2012), initiating observational studies of angular momentum transport in stars with stellar evolution. With Kepler data, there has now even been an asteroseismic determination of core-tosurface rotation in a main-sequence star (Kurtz et al. 2014). The emphasis of the Kepler search for h ...
... (Beck et al. 2012), initiating observational studies of angular momentum transport in stars with stellar evolution. With Kepler data, there has now even been an asteroseismic determination of core-tosurface rotation in a main-sequence star (Kurtz et al. 2014). The emphasis of the Kepler search for h ...
Accretion models
... •Accretion energy is the most likely source for the extra emission of CTTS, and it is naturally expected to be released in the process of star formation. •TTS emission line profiles cannot be interpreted in the frame of a spheric wind or collapse. ...
... •Accretion energy is the most likely source for the extra emission of CTTS, and it is naturally expected to be released in the process of star formation. •TTS emission line profiles cannot be interpreted in the frame of a spheric wind or collapse. ...
O stars with weak winds: the Galactic case - Max-Planck
... the broader the profile, the lower the precision of the fit of the line. The typical error on Teff is usually of ± 2000 K but can be reduced when many optical He lines are available. Note that the errors we give are 2σ errors (we have Teff − error < Teff < Teff + error). We also checked that our fin ...
... the broader the profile, the lower the precision of the fit of the line. The typical error on Teff is usually of ± 2000 K but can be reduced when many optical He lines are available. Note that the errors we give are 2σ errors (we have Teff − error < Teff < Teff + error). We also checked that our fin ...
Formation of millisecond pulsars with CO white dwarf companions–I
... parameter of δ OV = 0.20 (Claret 2007) allows for donor masses as low as 2.2 M to produce a final WD mass of 0.50 M . Hence, 4.4 ≤ k ≤ 5.2 and we can now use equation (2) to find the pre-CE orbital separation, a0 and hence the radius of the Roche lobe filling donor star. In Fig. 2 we demonstrate t ...
... parameter of δ OV = 0.20 (Claret 2007) allows for donor masses as low as 2.2 M to produce a final WD mass of 0.50 M . Hence, 4.4 ≤ k ≤ 5.2 and we can now use equation (2) to find the pre-CE orbital separation, a0 and hence the radius of the Roche lobe filling donor star. In Fig. 2 we demonstrate t ...
microquasars
... -THE PHYSICS OF RELATIVISTIC JETS FROM BH’s -THE CONNECTION BETWEEN ACCRETION & EJECTION -THE FORMATION OF BLACK HOLES AND NEUTRON STARS: Can stars of >40 Msolar end as neutron stars rather than BHs ? Do BHs of >10 Msolar form promptly rather than in bright SN ? ...
... -THE PHYSICS OF RELATIVISTIC JETS FROM BH’s -THE CONNECTION BETWEEN ACCRETION & EJECTION -THE FORMATION OF BLACK HOLES AND NEUTRON STARS: Can stars of >40 Msolar end as neutron stars rather than BHs ? Do BHs of >10 Msolar form promptly rather than in bright SN ? ...
Studying explosive phenomena in astrophysics by the example of
... The characteristic time scales of the life of stars, from millions to billions years, don’t allow us to trace the entire life cycle of any concrete star. But huge number of observed stars gives us an opportunity to observe them at different stages of their existence - from initial formation by conde ...
... The characteristic time scales of the life of stars, from millions to billions years, don’t allow us to trace the entire life cycle of any concrete star. But huge number of observed stars gives us an opportunity to observe them at different stages of their existence - from initial formation by conde ...
Article PDF - IOPscience
... orders of magnitude below the ULX range (Linden et al. 2010), (2) the donor star must be hydrogen rich, as a helium star with mass 5 M cannot fill its Roche lobe in a 2.5 days period orbit, independent of its evolutionary stage, (3) the evolutionary mechanism must have either a long lifetime, or a ...
... orders of magnitude below the ULX range (Linden et al. 2010), (2) the donor star must be hydrogen rich, as a helium star with mass 5 M cannot fill its Roche lobe in a 2.5 days period orbit, independent of its evolutionary stage, (3) the evolutionary mechanism must have either a long lifetime, or a ...
Cygnus X-1 poster (Massive Star Workshop)
... preSN preSN preSN V the evolution of massive stars. A discussion on this limit can –M confidence levels, which shows that if M is less than (V0 ) from kGaussian distributions. current age isHe He prog Belczynski, Bulik,and T., Fryer, C.,during et al. 2010, 714, 1217 event. Lestrade, J.-F., Preston, ...
... preSN preSN preSN V the evolution of massive stars. A discussion on this limit can –M confidence levels, which shows that if M is less than (V0 ) from kGaussian distributions. current age isHe He prog Belczynski, Bulik,and T., Fryer, C.,during et al. 2010, 714, 1217 event. Lestrade, J.-F., Preston, ...
Basic Tools for Studies on the Formation and Disruption of Star
... systematic decrease of the (logarithmic) slope from roughly −1.8 at low luminosities to roughly −2.8 at high luminosities. The empirical LFs can be reproduced by model LFs using an underlying cluster IMF with a Schechter type truncation around M∗ ≈ 2 × 105 M⊙ . This value of M⋆ can not be universal ...
... systematic decrease of the (logarithmic) slope from roughly −1.8 at low luminosities to roughly −2.8 at high luminosities. The empirical LFs can be reproduced by model LFs using an underlying cluster IMF with a Schechter type truncation around M∗ ≈ 2 × 105 M⊙ . This value of M⋆ can not be universal ...
variable star type designations in vsx
... Spotted stars that weren't classified into a particular class. All the SPOTTED stars in the UNSW list and the very small amplitude spotted stars found by Kepler are included here. Also, some stars that don't fit the current subtypes due to their physical properties have been classified as such (brow ...
... Spotted stars that weren't classified into a particular class. All the SPOTTED stars in the UNSW list and the very small amplitude spotted stars found by Kepler are included here. Also, some stars that don't fit the current subtypes due to their physical properties have been classified as such (brow ...
... of the main sequence, consistent with moderate (",20 per cent) contamination of the secondary light by an accretion disc. We use the K magnitudes to estimate the distances of the stars. We show that most lie within about 400 pc, and only two of the stars in our sample (RU LMi and DO Leo) are convinc ...
A Study of Herbig Ae Be Star HD 163296: Variability in
... Zero-Age Main Sequence The Hertzsprung-Russell (HR) diagram is the chart which shows stars’ re- ...
... Zero-Age Main Sequence The Hertzsprung-Russell (HR) diagram is the chart which shows stars’ re- ...
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.