ongoing massive star formation in the bulge of m511 hjglm lamers,2
... e.g., Millard et al. 1999). The galaxy was observed through the broadband Ðlters F255W and F336W in 1994 and through the broadband Ðlters F439W, F555W, F675W, and F814W in 1995. We will refer to these Ðlters as the UV, U, B, V , R, and I Ðlters. The observations in the UV, U, and B Ðlters were split ...
... e.g., Millard et al. 1999). The galaxy was observed through the broadband Ðlters F255W and F336W in 1994 and through the broadband Ðlters F439W, F555W, F675W, and F814W in 1995. We will refer to these Ðlters as the UV, U, B, V , R, and I Ðlters. The observations in the UV, U, and B Ðlters were split ...
PowerPoint
... – Topics covered in lectures should be stressed. – Homework questions have good examples of questions that may show up on the exam. An excellent way to begin studying is to review the homework problems, particularly those you missed (or got right but were not so sure about). Be sure you understand w ...
... – Topics covered in lectures should be stressed. – Homework questions have good examples of questions that may show up on the exam. An excellent way to begin studying is to review the homework problems, particularly those you missed (or got right but were not so sure about). Be sure you understand w ...
PLANETS AND INFRARED EXCESSES: PRELIMINARY RESULTS
... ring was chosen. Because the accuracy of the 70 m data is limited by background noise, rather than instrumental effects, such a large aperture contains an undesirable amount of sky fluctuations. In order to maximize S/ N, a smaller aperture is more appropriate at 70 m—just 1.5 pixels in radius. Wi ...
... ring was chosen. Because the accuracy of the 70 m data is limited by background noise, rather than instrumental effects, such a large aperture contains an undesirable amount of sky fluctuations. In order to maximize S/ N, a smaller aperture is more appropriate at 70 m—just 1.5 pixels in radius. Wi ...
Chapter 3a powerpoint presentation
... Absolute Magnitude We are unable to tell just by looking at the night sky if one star is fainter than another because it is intrinsically fainter (ie. lower luminosity) or just further away. To realistically compare stars on an equal basis we introduce the concept of Absolute magnitude (M) which is ...
... Absolute Magnitude We are unable to tell just by looking at the night sky if one star is fainter than another because it is intrinsically fainter (ie. lower luminosity) or just further away. To realistically compare stars on an equal basis we introduce the concept of Absolute magnitude (M) which is ...
Variable stars in the globular cluster M 92
... For v13 (Nassau’s no. 14) he detected variations, but was unable to derive a period. He supposed, however, that if the light variations are real, and if they are periodic, the period should be close to 0.3 d. All 14 new RR Lyrae candidates he observed turned out to be constant, while three giants re ...
... For v13 (Nassau’s no. 14) he detected variations, but was unable to derive a period. He supposed, however, that if the light variations are real, and if they are periodic, the period should be close to 0.3 d. All 14 new RR Lyrae candidates he observed turned out to be constant, while three giants re ...
Metallicity, Age, and Mass of Star Forming Galaxies at z~3
... spectroscopic follow up of color selected LBGs. The two samples are consistent with having similar colors. ...
... spectroscopic follow up of color selected LBGs. The two samples are consistent with having similar colors. ...
![An improved classification of B[e]-type stars](http://s1.studyres.com/store/data/015293756_1-5784ffaa4d7d33ad2633e3151daf904c-300x300.png)
An improved classification of B[e]-type stars
... If a star satisfies these criteria, the star shows the ”B[e] phenomenon”. In addition to these primary criteria, the optical spectrum may also show permitted and forbidden emission lines of higher ionization species, e.g. He ii λ4686, [O iii] λ5007, but this is not a defining characteristic. These s ...
... If a star satisfies these criteria, the star shows the ”B[e] phenomenon”. In addition to these primary criteria, the optical spectrum may also show permitted and forbidden emission lines of higher ionization species, e.g. He ii λ4686, [O iii] λ5007, but this is not a defining characteristic. These s ...
Chemical Signatures in Dwarf Galaxies
... can come from H ii region emission lines, planetary nebulae, or supernova remnants, but mostly they come from stars. Since stars can live a very long time, for example, a 0.8 MA star born at the time of the Big Bang would only now be ascending the red giant branch, and, if, for the most part, its qu ...
... can come from H ii region emission lines, planetary nebulae, or supernova remnants, but mostly they come from stars. Since stars can live a very long time, for example, a 0.8 MA star born at the time of the Big Bang would only now be ascending the red giant branch, and, if, for the most part, its qu ...
Subatomic particle processes within neutron stars
... Volkoff carried out the first calculations of the structure of neutron stars in 1939, based on the pioneering work of Landau.[4] We will briefly consider in the following lines some of the striking features of the neutron stars to later introduce the even more striking consequences of these properti ...
... Volkoff carried out the first calculations of the structure of neutron stars in 1939, based on the pioneering work of Landau.[4] We will briefly consider in the following lines some of the striking features of the neutron stars to later introduce the even more striking consequences of these properti ...
molecular observations of H CO , 13CO, HCN how to determine
... density. The stellar positions are from Kenyon (2007). The diamonds indicate diffuse or extended sources (of which there are 44 in the region mapped), the squares indicate Class I or younger stars (18), and the asterisks indicate T-Tauri stars (168). It is evident that the ...
... density. The stellar positions are from Kenyon (2007). The diamonds indicate diffuse or extended sources (of which there are 44 in the region mapped), the squares indicate Class I or younger stars (18), and the asterisks indicate T-Tauri stars (168). It is evident that the ...
Today Only, A New Exhibit: M,L, and T Dwarfs!
... Mass <~ 75 Jupiter Masses which is 8 percent of our Sun's mass Burns Deuterium at >~ 13 Jupiter Masses for ~ 10’s of Myrs heating from contraction Highly convective Hot Corona may disappear around 2770 K i.e. LP 944-20 ...
... Mass <~ 75 Jupiter Masses which is 8 percent of our Sun's mass Burns Deuterium at >~ 13 Jupiter Masses for ~ 10’s of Myrs heating from contraction Highly convective Hot Corona may disappear around 2770 K i.e. LP 944-20 ...
Seyfert Galaxies - Otterbein University
... • Edwin Hubble identified single stars in the Andromeda nebula (“turning” it into a galaxy) • Measured the distance to Andromeda to be 1 million Ly (modern value: 2.2 mill. Ly) • Conclusion: it is 20 times more distant than the milky way’s radius Extragalacticity! ...
... • Edwin Hubble identified single stars in the Andromeda nebula (“turning” it into a galaxy) • Measured the distance to Andromeda to be 1 million Ly (modern value: 2.2 mill. Ly) • Conclusion: it is 20 times more distant than the milky way’s radius Extragalacticity! ...
Test#4
... c) fairly uniform, d) has remained the same as it was during the big bang 7. The location of our Sun in the galaxy is approximately a) near the core, b) near the outer edge c) about 2/3 of the way out to the edge, d) not currently determined 8. About how long does it take for the Sun to complete one ...
... c) fairly uniform, d) has remained the same as it was during the big bang 7. The location of our Sun in the galaxy is approximately a) near the core, b) near the outer edge c) about 2/3 of the way out to the edge, d) not currently determined 8. About how long does it take for the Sun to complete one ...
Molecular Cooling Rates (Neufeld, Lepp and Melnick 1995)
... Canonical picture • AGB stars are intermediate mass stars which are burning H or He in a shell • Stellar radius ~ 1 a.u. • Stellar luminosity ~ 104 L • Photospheric temperature ~ 2000 – 3000 K • Long period pulsational variables (P ~ 1 yr) • Outflowing envelopes (v ~ 10 km/s) driven by radiation p ...
... Canonical picture • AGB stars are intermediate mass stars which are burning H or He in a shell • Stellar radius ~ 1 a.u. • Stellar luminosity ~ 104 L • Photospheric temperature ~ 2000 – 3000 K • Long period pulsational variables (P ~ 1 yr) • Outflowing envelopes (v ~ 10 km/s) driven by radiation p ...
Chapter 4 On the possibility of a helium white dwarf donor in the
... Second, it has an X-ray luminosity which is low for an active LMXB, namely less than or equal to 1% of the Eddington limit for a canonical (1.4 M⊙ , 10 km radius) neutron star (Jonker et al. 2001). Third, 2S 0918–549 appears to have an unusually high Ne/O abundance ratio, a characteristic which it s ...
... Second, it has an X-ray luminosity which is low for an active LMXB, namely less than or equal to 1% of the Eddington limit for a canonical (1.4 M⊙ , 10 km radius) neutron star (Jonker et al. 2001). Third, 2S 0918–549 appears to have an unusually high Ne/O abundance ratio, a characteristic which it s ...
Boron Abundances Across the" Li
... below the SCZ. The more observational information we have for all three light elements, the better we will be able to understand the internal mixing processes and then build more sophisticated stellar evolution models. Studies of Li abundances in clusters younger than the Hyades, such as Pleiades an ...
... below the SCZ. The more observational information we have for all three light elements, the better we will be able to understand the internal mixing processes and then build more sophisticated stellar evolution models. Studies of Li abundances in clusters younger than the Hyades, such as Pleiades an ...
Modeling non-thermal emission from stellar bow shocks
... BD+43 3654 has been reported to have formed a bow shock detected in the IR (Comerón & Pasquali 2007) and in radio (Benaglia et al. 2010). Both observations are coincident and extensive. Assuming the velocity of this star is 67 km s−1 (Kobulnicky et al. 2010), the mass-loss rate 10−5 M⊙ yr−1 (Markov ...
... BD+43 3654 has been reported to have formed a bow shock detected in the IR (Comerón & Pasquali 2007) and in radio (Benaglia et al. 2010). Both observations are coincident and extensive. Assuming the velocity of this star is 67 km s−1 (Kobulnicky et al. 2010), the mass-loss rate 10−5 M⊙ yr−1 (Markov ...
Nuclear Reactions
... Laboratory measurements of S(E) are in general available over a range in E much higher than those prevalent in stellar interiors, where the values of S(E) are too small for accurate lab measurements. Existing lab measurements thus often require extrapolation over many orders of magnitude to the smal ...
... Laboratory measurements of S(E) are in general available over a range in E much higher than those prevalent in stellar interiors, where the values of S(E) are too small for accurate lab measurements. Existing lab measurements thus often require extrapolation over many orders of magnitude to the smal ...
Chapter 21 - apel slice
... On a clear night, your eyes can see at most a few thousand stars. But with a telescope, you can see many millions. Why? The light from stars spreads out as it moves through space, and your eyes are too small to gather much light. Telescopes are instruments that collect and focus light and other form ...
... On a clear night, your eyes can see at most a few thousand stars. But with a telescope, you can see many millions. Why? The light from stars spreads out as it moves through space, and your eyes are too small to gather much light. Telescopes are instruments that collect and focus light and other form ...
Complete set of notes, one file
... Almost all the astrophysical information we can derive about distant sources results from the radiation that reaches us from them. Our starting point is, therefore, a review of the principal ways of describing radiation. (In principle, this could include polarization properties, but we neglect that ...
... Almost all the astrophysical information we can derive about distant sources results from the radiation that reaches us from them. Our starting point is, therefore, a review of the principal ways of describing radiation. (In principle, this could include polarization properties, but we neglect that ...
Example 3.1
... A useful way to picture this relationship is to plot a point for each observation, where the coordinates of the point represent the values of the two variables. ...
... A useful way to picture this relationship is to plot a point for each observation, where the coordinates of the point represent the values of the two variables. ...
Astronomy 112: The Physics of Stars Class 8 Notes: Nuclear
... sensitive to temperature, so that they can go very rapidly from negligible to huge. As a result, there is usually only a narrow range of temperatures where a reaction can occur for a period of time comparable to tKH , the thermal timescale of the star. At lower temperatures the reaction would produc ...
... sensitive to temperature, so that they can go very rapidly from negligible to huge. As a result, there is usually only a narrow range of temperatures where a reaction can occur for a period of time comparable to tKH , the thermal timescale of the star. At lower temperatures the reaction would produc ...
Detecting Stars at the Galactic Centre via Synchrotron Emission
... where Ro is the standoff radius and vw the wind velocity. The peak luminosity lasts for the pericenter crossing timescale with typical values ∼ 1 yr. The precise shape of the peak depends on the orbital parameters, the ambient gas distribution, and the wind mass loss rate. The characteristic timesca ...
... where Ro is the standoff radius and vw the wind velocity. The peak luminosity lasts for the pericenter crossing timescale with typical values ∼ 1 yr. The precise shape of the peak depends on the orbital parameters, the ambient gas distribution, and the wind mass loss rate. The characteristic timesca ...
Accreting neutron stars: strong gravity and type I bursts - UvA-DARE
... However, even more is still left to be released: indeed, much more of the potential energy can be emitted during the final stages of accretion onto the stellar surface, and there the matter can also burn via nuclear processes similar to those active in stellar interiors or in similar systems like ac ...
... However, even more is still left to be released: indeed, much more of the potential energy can be emitted during the final stages of accretion onto the stellar surface, and there the matter can also burn via nuclear processes similar to those active in stellar interiors or in similar systems like ac ...
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.