Document
... Efficiency for stars on non-circular orbits? How to produce/maintain very narrow iron abundance distribution at given radius? ...
... Efficiency for stars on non-circular orbits? How to produce/maintain very narrow iron abundance distribution at given radius? ...
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... gradually puffed up (thicker) due to dynamical effects • The thick disk: it could be a thin disk that was dynamically heated by minor mergers with other galaxies • The bulge: the original, self-enriched stellar population that formed at the bottom of the galaxy’s potential well • The bar: formed ...
... gradually puffed up (thicker) due to dynamical effects • The thick disk: it could be a thin disk that was dynamically heated by minor mergers with other galaxies • The bulge: the original, self-enriched stellar population that formed at the bottom of the galaxy’s potential well • The bar: formed ...
2015 SAO Summer Intern AAS Abstracts - Harvard
... This is a preliminary report on the mass of remaining hydrogen envelopes for stars massive enough to explode under core collapse. Using the stellar evolution code, MESA, our initial findings suggest that a significant fraction of massive stars with MZAMS = 20 − 60 Msun lose all but 10−3 Msun −10−1 M ...
... This is a preliminary report on the mass of remaining hydrogen envelopes for stars massive enough to explode under core collapse. Using the stellar evolution code, MESA, our initial findings suggest that a significant fraction of massive stars with MZAMS = 20 − 60 Msun lose all but 10−3 Msun −10−1 M ...
Progenitors and Hydrodynamics of Type II and lb Supernovae
... ilar to that accompanying iron core collapse in larger stars, but with some observational distinctions. First, the density gradient at the edge of the ONeMg core is very steep. Little 56 Ni will be produced. Mayle & Wilson (1988) calculate ~0.002 M 0 of 56 Ni for a model of this sort. Also the envel ...
... ilar to that accompanying iron core collapse in larger stars, but with some observational distinctions. First, the density gradient at the edge of the ONeMg core is very steep. Little 56 Ni will be produced. Mayle & Wilson (1988) calculate ~0.002 M 0 of 56 Ni for a model of this sort. Also the envel ...
Gamma-Ray-Bursts in Nuclear Astrophysics Giuseppe Pagliara
... non-thermal power-law. Such long delays and the nonthermal origin of their spectra are hard to reconcile with any model for the ...
... non-thermal power-law. Such long delays and the nonthermal origin of their spectra are hard to reconcile with any model for the ...
kd - The HST Treasury Program on Eta Carinae
... Detection of the secondary star is highly desirable because that would eliminate single-star models. Unfortunately, as we explained in sections 2—4 above, there is no proof that any emission seen with FUSE came from a second star. It’s not hard to imagine a single-star model. The equatorial photosph ...
... Detection of the secondary star is highly desirable because that would eliminate single-star models. Unfortunately, as we explained in sections 2—4 above, there is no proof that any emission seen with FUSE came from a second star. It’s not hard to imagine a single-star model. The equatorial photosph ...
Red Supergiants, Luminous Blue Variables and Wolf
... der Hucht 1988) are too weak for producing this kind of evolution for stars in the mass range between 12 and 25-30 M (at least for standard non-rotating models). However the uncertainties are large, actually, the determinations of the mass loss during the RSG phase is still more difficult than in t ...
... der Hucht 1988) are too weak for producing this kind of evolution for stars in the mass range between 12 and 25-30 M (at least for standard non-rotating models). However the uncertainties are large, actually, the determinations of the mass loss during the RSG phase is still more difficult than in t ...
Oort Cloud Evolu on in a Long
... • With an intermediate to large mass of the Sun’s birth cluster, a primordial OC would likely lose almost all its members, most of the survivors forming a Vght inner core • For the large mass, ...
... • With an intermediate to large mass of the Sun’s birth cluster, a primordial OC would likely lose almost all its members, most of the survivors forming a Vght inner core • For the large mass, ...
Constellations and Light Pollution
... formed may study the light of galaxies and quasars at incredibly vast distances from Earth. These images offer information about faraway corners of the universe, helping us understand how our own world was formed. Yet, after traveling countless light years, the light from these objects can be lost a ...
... formed may study the light of galaxies and quasars at incredibly vast distances from Earth. These images offer information about faraway corners of the universe, helping us understand how our own world was formed. Yet, after traveling countless light years, the light from these objects can be lost a ...
PowerPoint Presentation - Neutron stars, pulsars and black
... than 100 times per second (the first was spinning 640 times per second) threw the field for a loop. When some millisecond pulsars were discovered in old star clusters it was even more confusing. • Eventually it was determined that all millisecond pulsars were in close binary systems and were `spun u ...
... than 100 times per second (the first was spinning 640 times per second) threw the field for a loop. When some millisecond pulsars were discovered in old star clusters it was even more confusing. • Eventually it was determined that all millisecond pulsars were in close binary systems and were `spun u ...
The Structure of White Dwarf and Neutron Stars∗ Abstract
... Stars in their prime, while they are on the “main sequence,” support themselves against gravitational collapse by the pressure of hot gas, the energy being released in nuclear fusion reactions at the star’s core. For most of its life, the fusion reactions are dominated by protons (hydrogen nuclei) f ...
... Stars in their prime, while they are on the “main sequence,” support themselves against gravitational collapse by the pressure of hot gas, the energy being released in nuclear fusion reactions at the star’s core. For most of its life, the fusion reactions are dominated by protons (hydrogen nuclei) f ...
Document
... Flare <15s to 1 hr, repeats hrs - days Amplitude up to 4 mag Opt is thermal brem at T ~ 107K, radio is non-thermal Between flares, spectrum is K-M with CaII, H emission ...
... Flare <15s to 1 hr, repeats hrs - days Amplitude up to 4 mag Opt is thermal brem at T ~ 107K, radio is non-thermal Between flares, spectrum is K-M with CaII, H emission ...
Lec10
... Observations in the 1990s showed that many gammaray bursts were coming from very distant galaxies They must be among the most powerful explosions in the universe—could be the formation of a black hole ...
... Observations in the 1990s showed that many gammaray bursts were coming from very distant galaxies They must be among the most powerful explosions in the universe—could be the formation of a black hole ...
Expanding the Catalog: Considering the Importance
... makes a bigger difference to the evolution relative to its abundance in stars. Oxygen is not only much more abundant than carbon, but also has a high contribution to the opacity. Table 2 shows ∆(L/LZAM S ) at each mass and end-member composition for all elements. Stars with longer MS lifetimes than ...
... makes a bigger difference to the evolution relative to its abundance in stars. Oxygen is not only much more abundant than carbon, but also has a high contribution to the opacity. Table 2 shows ∆(L/LZAM S ) at each mass and end-member composition for all elements. Stars with longer MS lifetimes than ...
PowerPoint Presentation - Neutron stars, pulsars and black holes
... than 100 times per second (the first was spinning 640 times per second) threw the field for a loop. When some millisecond pulsars were discovered in old star clusters it was even more confusing. • Eventually it was determined that all millisecond pulsars were in close binary systems and were `spun u ...
... than 100 times per second (the first was spinning 640 times per second) threw the field for a loop. When some millisecond pulsars were discovered in old star clusters it was even more confusing. • Eventually it was determined that all millisecond pulsars were in close binary systems and were `spun u ...
Observed properties of SN
... Note that radioactive heating is released mainly as gamma rays, which are later thermalized. Hence heating becomes less efficient in the optical etc. when the mean free path of the gamma rays is comparable with the size of the ejecta. ...
... Note that radioactive heating is released mainly as gamma rays, which are later thermalized. Hence heating becomes less efficient in the optical etc. when the mean free path of the gamma rays is comparable with the size of the ejecta. ...
HOW TO MAKE A SINGLETON sdB STAR VIA ACCELERATED STELLAR... Drew Clausen and Richard A. Wade
... He when the core has reached 95% of the mass it will have at the tip of the RGB (D’Cruz et al. 1996), the mass range includes the red region and extends to the lower values shown in blue. These models were computed with SSE assuming solar abundances. This band shifts to the right for stars with Y = ...
... He when the core has reached 95% of the mass it will have at the tip of the RGB (D’Cruz et al. 1996), the mass range includes the red region and extends to the lower values shown in blue. These models were computed with SSE assuming solar abundances. This band shifts to the right for stars with Y = ...
Practice Exam 3 - SFSU Physics & Astronomy
... (d) How does the total kinetic energy in the center of mass frame compare to total kinetic energy of the “lab” frame of parts (a) and (b)? 7. Two stars of equal mass M and radius R are in initially at rest separated by a distance D > 2R. (a)With what speed will they eventually collide if no other fo ...
... (d) How does the total kinetic energy in the center of mass frame compare to total kinetic energy of the “lab” frame of parts (a) and (b)? 7. Two stars of equal mass M and radius R are in initially at rest separated by a distance D > 2R. (a)With what speed will they eventually collide if no other fo ...
Document
... It has similar luminosity to Sculptor and it shows hints of age gradients (e.g. MartinezDelgado, Gallart and Aparicio 1999, wide area but shallow photometry) ...
... It has similar luminosity to Sculptor and it shows hints of age gradients (e.g. MartinezDelgado, Gallart and Aparicio 1999, wide area but shallow photometry) ...
How to predict the meridian passage time of a star. This is not an
... various levels of the solution, depending on the accuracy needed. We will use as an example, the problem of finding the meridian passage of Deneb on July 1, 2010 at Lon 0°.... this was the requested location, though the procedure does not differ for other longitudes, as we will show. First, to get a ...
... various levels of the solution, depending on the accuracy needed. We will use as an example, the problem of finding the meridian passage of Deneb on July 1, 2010 at Lon 0°.... this was the requested location, though the procedure does not differ for other longitudes, as we will show. First, to get a ...
Please read the following excerpt from an editorial about the Atkins
... Supernovae are stupendous explosions that destroy an entire star. The "nova" ("new") part of their name is because they are mostly seen as `new' stars appearing suddenly where no star was seen before because of their sudden increase in brightness. They can, for a few days, rival the combined light o ...
... Supernovae are stupendous explosions that destroy an entire star. The "nova" ("new") part of their name is because they are mostly seen as `new' stars appearing suddenly where no star was seen before because of their sudden increase in brightness. They can, for a few days, rival the combined light o ...
Neutron Density and Neutron Source Determination in Barium
... and decided to find out what this was about. First I asked some of my colleagues about Fontenelle, but none of them seemed to know him. "At which observatory does he work?" was one of the kind, but not very helpful replies. Calling the Bavarian State Library in Munich, Ilearned that no less than thr ...
... and decided to find out what this was about. First I asked some of my colleagues about Fontenelle, but none of them seemed to know him. "At which observatory does he work?" was one of the kind, but not very helpful replies. Calling the Bavarian State Library in Munich, Ilearned that no less than thr ...
Gamma Ray Bursts: The biggest bang since the big one!
... • Cook until all hydrogen fuel eventually exhausted. ...
... • Cook until all hydrogen fuel eventually exhausted. ...
Modeling White Dwarf Star Magnetization - Blogs at H-SC
... and because there is no more fusion, or producing heat energy, the cooling process slows down gradually. A white dwarf star is believed white due to its color of the temperature on H-R diagram. However, most of the white dwarf stars have the surface temperature that is still hotter than that of the ...
... and because there is no more fusion, or producing heat energy, the cooling process slows down gradually. A white dwarf star is believed white due to its color of the temperature on H-R diagram. However, most of the white dwarf stars have the surface temperature that is still hotter than that of the ...
Measuring with CCD Soft2008-2
... 9. Finding the centroid: In step 7 you found the pixel in which the number of photons from the star was the largest. Since the field of view is approximately 20’ x 19’, and there are 1280x1024 pixels, each pixel corresponds to 1.” (You can calculate the exact field of view by noting that the chip si ...
... 9. Finding the centroid: In step 7 you found the pixel in which the number of photons from the star was the largest. Since the field of view is approximately 20’ x 19’, and there are 1280x1024 pixels, each pixel corresponds to 1.” (You can calculate the exact field of view by noting that the chip si ...
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.