rasc2012(97)
... L filter with Ha overlay showing star forming regions along spiral arms C14 f/7 Atik 314L+ ...
... L filter with Ha overlay showing star forming regions along spiral arms C14 f/7 Atik 314L+ ...
HD 91669b: A New Brown Dwarf Candidate from the McDonald
... For HD 91669, this a priori probability is 7.6%. Kürster et al. (2008) were able to combine Hipparcos astrometry with a radial-velocity orbital solution to place additional constraints on the inclination of GJ 1046b, a brown dwarf candidate in close orbit about an M2.5 star. Similarly, we also trie ...
... For HD 91669, this a priori probability is 7.6%. Kürster et al. (2008) were able to combine Hipparcos astrometry with a radial-velocity orbital solution to place additional constraints on the inclination of GJ 1046b, a brown dwarf candidate in close orbit about an M2.5 star. Similarly, we also trie ...
TOWARD A MODEL FOR THE Be BINARY SYSTEM PER 1
... with the Paschen emissions and which were made from considerably lower dispersion plates than the rest of my data seem to indicate that these lines follow the primary and their emission edges do not reveal the influence of any emission from the secondary. Clearly, the conditions under which they are ...
... with the Paschen emissions and which were made from considerably lower dispersion plates than the rest of my data seem to indicate that these lines follow the primary and their emission edges do not reveal the influence of any emission from the secondary. Clearly, the conditions under which they are ...
Central Massive Objects: The Stellar Nuclei – Black Hole
... holes (IMBHs) in globular clusters. Clearly, the most compelling evidence is the detection of non-thermal emission, seen, for example, for G1 in M31, but globular clusters have very little or even no gas and so the emission is very faint or absent. The evidence from the density structure is still co ...
... holes (IMBHs) in globular clusters. Clearly, the most compelling evidence is the detection of non-thermal emission, seen, for example, for G1 in M31, but globular clusters have very little or even no gas and so the emission is very faint or absent. The evidence from the density structure is still co ...
Slides from Lecture19 - Department of Physics & Astronomy
... Determining Size of MW Galaxy • We have not always known that the diameter of our Galaxy is ~ 50 kpc (as illustrated in following slide) • For example, Herschel’s map of our Galaxy (1785) based on star counts … – Thin disk not much more than 1 kpc across – Sun approximately at center of disk ...
... Determining Size of MW Galaxy • We have not always known that the diameter of our Galaxy is ~ 50 kpc (as illustrated in following slide) • For example, Herschel’s map of our Galaxy (1785) based on star counts … – Thin disk not much more than 1 kpc across – Sun approximately at center of disk ...
Red Supergiants as Cosmic Abundance Probes
... the optical and near-infrared, from 0.3– 2.5 μm. This allowed us to verify that the temperatures we obtain from our narrow window in the J-band were consistent with those from fits to the spectral energy distributions. The agreement for the SMC stars was excellent, while the LMC stars were also simi ...
... the optical and near-infrared, from 0.3– 2.5 μm. This allowed us to verify that the temperatures we obtain from our narrow window in the J-band were consistent with those from fits to the spectral energy distributions. The agreement for the SMC stars was excellent, while the LMC stars were also simi ...
Data-mining in astrophysics. A search for new variable stars in
... is the ratio of the standard deviation of all means to the mean of all standard deviations. A properly chosen value separates stars with long-period or irregular variations, from short-period variables. This technique is a basis for variable star search in another main variability survey – ASAS (All ...
... is the ratio of the standard deviation of all means to the mean of all standard deviations. A properly chosen value separates stars with long-period or irregular variations, from short-period variables. This technique is a basis for variable star search in another main variability survey – ASAS (All ...
–1– 1. Convection Convection In Stars – Things We Need to
... The last few of above set of assumptions is sometimes called the Bousinesq approximation. ...
... The last few of above set of assumptions is sometimes called the Bousinesq approximation. ...
Star position tutorial
... – Circumpolar stars seem to move counter-clockwise around the stationary North Star. – These constellations and stars are visible any night of the year in the NORTHERN sky because they never rise or ...
... – Circumpolar stars seem to move counter-clockwise around the stationary North Star. – These constellations and stars are visible any night of the year in the NORTHERN sky because they never rise or ...
55 Ignacio Negueruela and Amparo Marco
... and a spectroscopic survey of likely members, showing that its population is much younger than implied by the single-color fit of Maciejewski & Niedzielski (2007). From our new data, we show that Be 55 is a young (log t ≈ 7.7) open cluster with a rich population of evolved stars. ...
... and a spectroscopic survey of likely members, showing that its population is much younger than implied by the single-color fit of Maciejewski & Niedzielski (2007). From our new data, we show that Be 55 is a young (log t ≈ 7.7) open cluster with a rich population of evolved stars. ...
Evolution of low- and intermediate mass stars
... massive stars. However, even in the more massive stars there is still a shell, somewhat outside the main energy-producing region, where the pp chain partially operates, burning H to 3He but not beyond. Because the pp chain is less sensitive to temperature than the CNO cycle, cores of lowmass stars a ...
... massive stars. However, even in the more massive stars there is still a shell, somewhat outside the main energy-producing region, where the pp chain partially operates, burning H to 3He but not beyond. Because the pp chain is less sensitive to temperature than the CNO cycle, cores of lowmass stars a ...
Some notes on the Inka constellations
... ‘constellation’ and grouped together very much as in the greco-roman tradition of the night sky. (b) Dark (or black) constellations, which are condensations of interstellar gas and dust which appear as dark spots or silhouettes against the bright and diffuse the Milky Way. It is well possible that he ...
... ‘constellation’ and grouped together very much as in the greco-roman tradition of the night sky. (b) Dark (or black) constellations, which are condensations of interstellar gas and dust which appear as dark spots or silhouettes against the bright and diffuse the Milky Way. It is well possible that he ...
Gravity-Bending Find Leads to Kepler Meeting Einstein
... Muirhead and his colleagues regularly use public Kepler data to search for and confirm planets around smaller stars, the red dwarfs, also known as M dwarfs. These stars are cooler and redder than our yellow sun. When the team first looked at the Kepler data for a target called KOI-256, they thought ...
... Muirhead and his colleagues regularly use public Kepler data to search for and confirm planets around smaller stars, the red dwarfs, also known as M dwarfs. These stars are cooler and redder than our yellow sun. When the team first looked at the Kepler data for a target called KOI-256, they thought ...
looking for progenitors of cool Ap stars
... the main-sequence phase, or are intrinsically slow rotators from their formation on. He also found no hint of magnetic braking on the MS from a study of the distribution of the rotation periods as a function of the gravity (North 1985), and this has been confirmed recently on the basis of new surfac ...
... the main-sequence phase, or are intrinsically slow rotators from their formation on. He also found no hint of magnetic braking on the MS from a study of the distribution of the rotation periods as a function of the gravity (North 1985), and this has been confirmed recently on the basis of new surfac ...
Self-Regulation of Star Formation in Low Metallicity Clouds
... we can observe objects such as galaxies and QSOs. On the other hand, the reionization of the intergalactic medium and the presence of heavy elements at high-z suggest that there are other populations of luminous objects, which precedes normal galaxies. Thus, a theoretical approach to reveal the form ...
... we can observe objects such as galaxies and QSOs. On the other hand, the reionization of the intergalactic medium and the presence of heavy elements at high-z suggest that there are other populations of luminous objects, which precedes normal galaxies. Thus, a theoretical approach to reveal the form ...
A third red supergiant rich cluster in the Scutum
... information is available, it is possible to identify a co-moving, physical association of RSGs, in order to discriminate between cluster and field stars (e.g. D07). However, the spectroscopic data presented here are of insufficient resolution to extract the radial velocity of cluster members, while, u ...
... information is available, it is possible to identify a co-moving, physical association of RSGs, in order to discriminate between cluster and field stars (e.g. D07). However, the spectroscopic data presented here are of insufficient resolution to extract the radial velocity of cluster members, while, u ...
Stellar Population Modeling of Galaxies in Nearby Groups
... The observed data and synthetic data are stored in Hess diagram. This grid forms as a two-dimensional histogram indicating the number of stars in some range (bin) of stellar magnitudes and colors. The best choice of the bin size depends on the observed CMD. These bins have to be large enough to cont ...
... The observed data and synthetic data are stored in Hess diagram. This grid forms as a two-dimensional histogram indicating the number of stars in some range (bin) of stellar magnitudes and colors. The best choice of the bin size depends on the observed CMD. These bins have to be large enough to cont ...
THE LUYINOSITY VARIABILITY OF SOLAR
... sequence, with a rotation period of a few days, or it may undergo a more dramatic spin-up, spin-down episode which, nevertheless, leads the star to almost the same rotational state after 100 Myr or so. Which path the young Sun took is probably unknowable but, in any case, left no strong mark on its ...
... sequence, with a rotation period of a few days, or it may undergo a more dramatic spin-up, spin-down episode which, nevertheless, leads the star to almost the same rotational state after 100 Myr or so. Which path the young Sun took is probably unknowable but, in any case, left no strong mark on its ...
New results on the age- activity relation from Kepler Alfio Bonanno
... Total oscillation power (in quiet Sun units) ...
... Total oscillation power (in quiet Sun units) ...
lecture2 - X-Ray
... Accretion in close binaries Accretion is the most powerful source of energy realized in Nature, which can give a huge energy output. When matter fall down onto the surface of a neutron star up to 10% of mc2 can be released. ...
... Accretion in close binaries Accretion is the most powerful source of energy realized in Nature, which can give a huge energy output. When matter fall down onto the surface of a neutron star up to 10% of mc2 can be released. ...
Astronomy 321 --- Homework Exercise: Star Wheel
... In the tables below, the first column is the constellation, with its standard 3-letter abbreviation in parentheses. For constellations with bright stars, one or two of these bright stars are listed in the 2nd column and should also be learned. The 3rd column lists other objects of interest (e.g., st ...
... In the tables below, the first column is the constellation, with its standard 3-letter abbreviation in parentheses. For constellations with bright stars, one or two of these bright stars are listed in the 2nd column and should also be learned. The 3rd column lists other objects of interest (e.g., st ...
Models of rapidly rotating neutron stars: remnants of accretion
... softest EOS. In addition, they found three models with 0:14 , b , 0:27. Rampp, Müller & Ruffert (1998) subsequently performed 3D simulations of three of these models. They found that the model with b . 0:27 shows a non-linear growth of a nonaxisymmetric dynamical instability dominated by the bar mo ...
... softest EOS. In addition, they found three models with 0:14 , b , 0:27. Rampp, Müller & Ruffert (1998) subsequently performed 3D simulations of three of these models. They found that the model with b . 0:27 shows a non-linear growth of a nonaxisymmetric dynamical instability dominated by the bar mo ...
planetary standard model
... Kepler identifies planets by detecting the slight dimming in a star’s light that occurs when an object passes in front of it. This ‘transit’ method can find planets much smaller than the radialvelocity technique can, giving astronomers a chance to detect other Earths. Kepler has now found 974 exopla ...
... Kepler identifies planets by detecting the slight dimming in a star’s light that occurs when an object passes in front of it. This ‘transit’ method can find planets much smaller than the radialvelocity technique can, giving astronomers a chance to detect other Earths. Kepler has now found 974 exopla ...
here - Canadian Institute for Theoretical Astrophysics
... Kepler identifies planets by detecting the slight dimming in a star’s light that occurs when an object passes in front of it. This ‘transit’ method can find planets much smaller than the radialvelocity technique can, giving astronomers a chance to detect other Earths. Kepler has now found 974 exopla ...
... Kepler identifies planets by detecting the slight dimming in a star’s light that occurs when an object passes in front of it. This ‘transit’ method can find planets much smaller than the radialvelocity technique can, giving astronomers a chance to detect other Earths. Kepler has now found 974 exopla ...
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.