![arXiv:1606.05438v1 [astro-ph.SR] 17 Jun 2016](http://s1.studyres.com/store/data/013048193_1-92364881cbcc0fdb7f47e7990acc1537-300x300.png)
arXiv:1606.05438v1 [astro-ph.SR] 17 Jun 2016
... phase is dominated both by the pp chains (mainly through 1 H(p, e+ ν)2 H) as well as by the CNO-cycle reaction 12 C(p, γ)13 N, followed by 13 N(β+ )13 C. When the temperature at the envelope base reaches Tbase = 2.4 × 107 K, the nuclear timescale becomes shorter than the accretion timescale, and acc ...
... phase is dominated both by the pp chains (mainly through 1 H(p, e+ ν)2 H) as well as by the CNO-cycle reaction 12 C(p, γ)13 N, followed by 13 N(β+ )13 C. When the temperature at the envelope base reaches Tbase = 2.4 × 107 K, the nuclear timescale becomes shorter than the accretion timescale, and acc ...
NAAP 3 of 7 Determining Astronomical Distance
... To the left is a graph of the periodicity of the Type I (high-metallicity) Cepheid variable S Nor. Cepheid S Nor has a period of pulsation of approximately 10 days and an average apparent magnitude mV = 6.5, what is its distance? We can use the pulsation period to estimate the absolute magnitude of ...
... To the left is a graph of the periodicity of the Type I (high-metallicity) Cepheid variable S Nor. Cepheid S Nor has a period of pulsation of approximately 10 days and an average apparent magnitude mV = 6.5, what is its distance? We can use the pulsation period to estimate the absolute magnitude of ...
A Type II Supernovae Constraint on $\ nu_e $
... shells of silicon, oxygen, nitrogen, carbon, helium, and finally an envelope of hydrogen. Nuclear reactions occur at the interfaces of these shells and between the shell and the core. The initial iron core of the progenitor star has a density of about 109 g/cm3 , and is primarily supported by the pr ...
... shells of silicon, oxygen, nitrogen, carbon, helium, and finally an envelope of hydrogen. Nuclear reactions occur at the interfaces of these shells and between the shell and the core. The initial iron core of the progenitor star has a density of about 109 g/cm3 , and is primarily supported by the pr ...
Pulsating Stars: Stars that Breathe
... Zhevakin’s zones Regions of the stellar interior where increased opacity can provide the necessary valve mechanism to drive pulsations, were first identified by the Russian astronomer S. A. Zhevakin in the 1950s. These were partial ionisation zones , where part of the energy released during a layer’ ...
... Zhevakin’s zones Regions of the stellar interior where increased opacity can provide the necessary valve mechanism to drive pulsations, were first identified by the Russian astronomer S. A. Zhevakin in the 1950s. These were partial ionisation zones , where part of the energy released during a layer’ ...
Chapter 7: The Galaxy, structure and content File
... The observational inputs are (i) M31 is 750 kpc away, and (ii) the Milky Way and M31 are approaching at 121 km s−1 . (The transverse velocity of M31, if any, is poorly determined at present.) A simple approximation for their dynamics is to suppose that they started out at the same point moving apart ...
... The observational inputs are (i) M31 is 750 kpc away, and (ii) the Milky Way and M31 are approaching at 121 km s−1 . (The transverse velocity of M31, if any, is poorly determined at present.) A simple approximation for their dynamics is to suppose that they started out at the same point moving apart ...
Day_6
... Is there a star that is in an unobservable position? When a star travels from being below the observer’s horizon to being above the observer’s horizon, is that star rising or ...
... Is there a star that is in an unobservable position? When a star travels from being below the observer’s horizon to being above the observer’s horizon, is that star rising or ...
Chapter 14 – Chemical Analysis
... the COG for Weak Lines • Both the ionization equilibrium and the opacity depend on surface gravity • For neutral lines of ionized species (e.g. Fe I in the Sun) these effects cancel, so the COG is independent of gravity • For ionized lines of ionized species (e.g Fe II in the Sun), the curves shift ...
... the COG for Weak Lines • Both the ionization equilibrium and the opacity depend on surface gravity • For neutral lines of ionized species (e.g. Fe I in the Sun) these effects cancel, so the COG is independent of gravity • For ionized lines of ionized species (e.g Fe II in the Sun), the curves shift ...
SUPERNOVA EMISSION FROM GAMMA RAYS TO THE INFRARED
... Supernovae are stellar explosions that produce emission in all electromagnetic bands for many decades or centuries. Except for the first few weeks, they are powered by radioactive decays from 56Co, 57Co and 44Ti. The computation of model spectra requires computing the degradation of gamma rays a ...
... Supernovae are stellar explosions that produce emission in all electromagnetic bands for many decades or centuries. Except for the first few weeks, they are powered by radioactive decays from 56Co, 57Co and 44Ti. The computation of model spectra requires computing the degradation of gamma rays a ...
OUR COSMIC NEIGHBORS Story of the Stars
... swinging around it. And probably most important of all, we now know that the movements of all heavenly bodies conform to a definite infinite system of law and order. A replica of the solar system is found even in the lowly atoms of the earth. “As above, so below.” May the reader find in these pages ...
... swinging around it. And probably most important of all, we now know that the movements of all heavenly bodies conform to a definite infinite system of law and order. A replica of the solar system is found even in the lowly atoms of the earth. “As above, so below.” May the reader find in these pages ...
The Galactic evolution of phosphorus
... planets” it cannot be excluded that they harbour undetected planets. We note, however, that all of the stars “without planets” in our sample, except for HD 215648 and HD 207978 have several high precision radial velocity points measured with the HARPS spectrograph at the ESO 3.6 m telescope. Given t ...
... planets” it cannot be excluded that they harbour undetected planets. We note, however, that all of the stars “without planets” in our sample, except for HD 215648 and HD 207978 have several high precision radial velocity points measured with the HARPS spectrograph at the ESO 3.6 m telescope. Given t ...
Formation of Massive Stars
... Due to the pressure difference in between HII and the surrounding neutral gas, HII regions will expand into the ambient medium • Classical analysis of the expansion assumes a homogeneous ambient medium and neglects stellar winds (cf. Spitzer 1978; ...
... Due to the pressure difference in between HII and the surrounding neutral gas, HII regions will expand into the ambient medium • Classical analysis of the expansion assumes a homogeneous ambient medium and neglects stellar winds (cf. Spitzer 1978; ...
10 New Constellations
... connects both constellations. M31 The most interesting object in the constellation is undoubtedly M31, otherwise known as the Andromeda Galaxy. Even though this galaxy is 2.5 million light years from Earth it is brighter than many stars in the night sky and is easily visible to the naked eye. The An ...
... connects both constellations. M31 The most interesting object in the constellation is undoubtedly M31, otherwise known as the Andromeda Galaxy. Even though this galaxy is 2.5 million light years from Earth it is brighter than many stars in the night sky and is easily visible to the naked eye. The An ...
MS PowerPoint - National Schools` Observatory
... This movement can cause light to be Doppler shifted as an atom in motion emits a photon, and because some of the atoms will be moving away from the observer and some moving towards, the overall effect will contain both blue-shift and red-shift components. ...
... This movement can cause light to be Doppler shifted as an atom in motion emits a photon, and because some of the atoms will be moving away from the observer and some moving towards, the overall effect will contain both blue-shift and red-shift components. ...
Cepheus (constellation)
... • Ridpath, Ian; Tirion, Wil (2001), Stars and Planets Guide, Princeton University Press, ISBN 0-691-08913-2 • Ian Ridpath and Wil Tirion (2007). Stars and Planets Guide, Collins, London. ISBN 978-0-00-725120-9. ...
... • Ridpath, Ian; Tirion, Wil (2001), Stars and Planets Guide, Princeton University Press, ISBN 0-691-08913-2 • Ian Ridpath and Wil Tirion (2007). Stars and Planets Guide, Collins, London. ISBN 978-0-00-725120-9. ...
part4.
... Appendix B Accreting on stars The study of accretion of matter like stellar dust on a star began with the discussions of Hoyle and Lyttleton [1]. The problem was that of the occurrence of ice age and such changes in earth’s climate. The geological and terrestrial studies could not account for such ...
... Appendix B Accreting on stars The study of accretion of matter like stellar dust on a star began with the discussions of Hoyle and Lyttleton [1]. The problem was that of the occurrence of ice age and such changes in earth’s climate. The geological and terrestrial studies could not account for such ...
Chapter 1 Introduction
... eye, similar clouds are numerously scattered throughout the Milky Way and some of them are close enough to Earth, so that they can be studied in great detail using telescopes. Stars are known to form inside these clouds and therefore moleclar clouds have been the subject of intense study during the ...
... eye, similar clouds are numerously scattered throughout the Milky Way and some of them are close enough to Earth, so that they can be studied in great detail using telescopes. Stars are known to form inside these clouds and therefore moleclar clouds have been the subject of intense study during the ...
Galactic Archaeology: Current Surveys
... a philosophical/sociological note, the RAVE survey was supported by the institutions and personal research grants of the participants and took advantage of the opportunity offered by the withdrawal of government support for the UK Schmidt, part of the worldwide transferral of resources to larger (an ...
... a philosophical/sociological note, the RAVE survey was supported by the institutions and personal research grants of the participants and took advantage of the opportunity offered by the withdrawal of government support for the UK Schmidt, part of the worldwide transferral of resources to larger (an ...
Stellar evolution
Stellar evolution is the process by which a star changes during its lifetime. Depending on the mass of the star, this lifetime ranges from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the age of the universe. The table shows the lifetimes of stars as a function of their masses. All stars are born from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main-sequence star.Nuclear fusion powers a star for most of its life. Initially the energy is generated by the fusion of hydrogen atoms at the core of the main-sequence star. Later, as the preponderance of atoms at the core becomes helium, stars like the Sun begin to fuse hydrogen along a spherical shell surrounding the core. This process causes the star to gradually grow in size, passing through the subgiant stage until it reaches the red giant phase. Stars with at least half the mass of the Sun can also begin to generate energy through the fusion of helium at their core, whereas more-massive stars can fuse heavier elements along a series of concentric shells. Once a star like the Sun has exhausted its nuclear fuel, its core collapses into a dense white dwarf and the outer layers are expelled as a planetary nebula. Stars with around ten or more times the mass of the Sun can explode in a supernova as their inert iron cores collapse into an extremely dense neutron star or black hole. Although the universe is not old enough for any of the smallest red dwarfs to have reached the end of their lives, stellar models suggest they will slowly become brighter and hotter before running out of hydrogen fuel and becoming low-mass white dwarfs.Stellar evolution is not studied by observing the life of a single star, as most stellar changes occur too slowly to be detected, even over many centuries. Instead, astrophysicists come to understand how stars evolve by observing numerous stars at various points in their lifetime, and by simulating stellar structure using computer models.In June 2015, astronomers reported evidence for Population III stars in the Cosmos Redshift 7 galaxy at z = 6.60. Such stars are likely to have existed in the very early universe (i.e., at high redshift), and may have started the production of chemical elements heavier than hydrogen that are needed for the later formation of planets and life as we know it.