the astrolabe - IREM Aix
... Front of the astrolabe 1. Matrix or mother: a disc of brass or bronze 10 to 50 cm in diameter which accommodates the various parts of the instrument. 2. Tympanum: an engraved plate that is placed on the mother. Designed for a given latitude, certain astrolabes possess several of these. 3. Spider (or ...
... Front of the astrolabe 1. Matrix or mother: a disc of brass or bronze 10 to 50 cm in diameter which accommodates the various parts of the instrument. 2. Tympanum: an engraved plate that is placed on the mother. Designed for a given latitude, certain astrolabes possess several of these. 3. Spider (or ...
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... • An alternative to searching for galaxies by their emission properties is to search for them by their absorption ...
... • An alternative to searching for galaxies by their emission properties is to search for them by their absorption ...
Data-mining in astrophysics. A search for new variable stars in
... Fourier analysis is performed at a later stage, after applying the other criteria to substantially reduce the number of variable star candidates. The reason is that Fourier analysis takes much computer time, always false periods exist along with the real, and human inspection is needed to clarify so ...
... Fourier analysis is performed at a later stage, after applying the other criteria to substantially reduce the number of variable star candidates. The reason is that Fourier analysis takes much computer time, always false periods exist along with the real, and human inspection is needed to clarify so ...
contributed talk in splinter session
... information on the structure of the magnetic field both across the surface and in the accretion shock. The low circular polarisation measured in photospheric lines rules out the presence of a global dipole, suggesting perhaps a complex field that may be locally very intense, but which is organised i ...
... information on the structure of the magnetic field both across the surface and in the accretion shock. The low circular polarisation measured in photospheric lines rules out the presence of a global dipole, suggesting perhaps a complex field that may be locally very intense, but which is organised i ...
Neutron Stars
... Note that M is independent of ρc and R in the ultra-relativistic limit. Thus as ρc → ∞, the electrons become more and more relativistic throughout the star, then R → 0 and the mass asymptotically will be given by equation (47). The mass limit (47) is called Chandrasekhar limit (MCh = 1.457M ) and i ...
... Note that M is independent of ρc and R in the ultra-relativistic limit. Thus as ρc → ∞, the electrons become more and more relativistic throughout the star, then R → 0 and the mass asymptotically will be given by equation (47). The mass limit (47) is called Chandrasekhar limit (MCh = 1.457M ) and i ...
The Milky Way Galaxy
... distribution of globular clusters and field stars, as well as large amounts of dark matter. ...
... distribution of globular clusters and field stars, as well as large amounts of dark matter. ...
Time From the Perspective of a Particle Physicist
... • It takes 1 day to complete the circle. • The rising and setting time of a star changes with the seasons. • Stars are directly overhead (zenith) 2 hours earlier each month. ...
... • It takes 1 day to complete the circle. • The rising and setting time of a star changes with the seasons. • Stars are directly overhead (zenith) 2 hours earlier each month. ...
Nuclear Reactions
... where δAB is 1 if A + B and 0 otherwise; this factor is needed so that identical pairs are not counted twice. vAB is the relative velocity of A with respect to B, σAB is the cross section, which is a function of vAB . We must view the reaction in the center of mass frame, and the kinetic energy E is ...
... where δAB is 1 if A + B and 0 otherwise; this factor is needed so that identical pairs are not counted twice. vAB is the relative velocity of A with respect to B, σAB is the cross section, which is a function of vAB . We must view the reaction in the center of mass frame, and the kinetic energy E is ...
Photoelectric Photometry of the Pleiades Student Manual
... The computer program you will use is a realistic simulation of a UBV photometer attached to a moderate sized research telescope. The telescope is controlled by a computer that allows you to move from star to star and make measurements. Different filters can be selected for each observation, and the ...
... The computer program you will use is a realistic simulation of a UBV photometer attached to a moderate sized research telescope. The telescope is controlled by a computer that allows you to move from star to star and make measurements. Different filters can be selected for each observation, and the ...
L25 A NEW CULPRIT IN THE SECOND
... reveal that the red horizontal branch (RHB) stars are strongly concentrated toward the center of the galaxy relative to the dominant old population in Sculptor, confirming an earlier claim of such a gradient. Since we find no radial gradients of the age or metallicity distribution within Sculptor, n ...
... reveal that the red horizontal branch (RHB) stars are strongly concentrated toward the center of the galaxy relative to the dominant old population in Sculptor, confirming an earlier claim of such a gradient. Since we find no radial gradients of the age or metallicity distribution within Sculptor, n ...
GoldCreation
... One of my favorite astronomy-themed t-shirts says “You are star dust”. It makes the point that we are all made from long dead stars. Of course, everything around us is also made of star stuff. This even includes rare elements such as gold. This paper discusses the processes of gold formation. Most m ...
... One of my favorite astronomy-themed t-shirts says “You are star dust”. It makes the point that we are all made from long dead stars. Of course, everything around us is also made of star stuff. This even includes rare elements such as gold. This paper discusses the processes of gold formation. Most m ...
IDENTIFICATION OF MAIN-SEQUENCE STARS WITH MID
... criteria, but some stars did not have GSC V-band counterparts, allowing for the inclusion of extremely red stars. A total of 164 new stellar classifications resulted from these observations. The stars were classified by eye using comparison spectra (Yamashita et al. 1976) to within two comparison te ...
... criteria, but some stars did not have GSC V-band counterparts, allowing for the inclusion of extremely red stars. A total of 164 new stellar classifications resulted from these observations. The stars were classified by eye using comparison spectra (Yamashita et al. 1976) to within two comparison te ...
Zapartas_deMink_Izzard_AA_2017
... Most massive stars, the progenitors of core-collapse supernovae, are in close binary systems and may interact with their companion through mass transfer or merging. We undertake a population synthesis study to compute the delay-time distribution of core-collapse supernovae, that is, the supernova ra ...
... Most massive stars, the progenitors of core-collapse supernovae, are in close binary systems and may interact with their companion through mass transfer or merging. We undertake a population synthesis study to compute the delay-time distribution of core-collapse supernovae, that is, the supernova ra ...
SMA Observations of AB Aur
... The CD around AB Aur was imaged in 12CO 3-2 and 345 GHz continuum using the SMA, revealing details of structures of the CD. The dust disk was clearly resolved, showing a ring-like structure around the central star. ...
... The CD around AB Aur was imaged in 12CO 3-2 and 345 GHz continuum using the SMA, revealing details of structures of the CD. The dust disk was clearly resolved, showing a ring-like structure around the central star. ...
Outta This World - Kent School District
... around like a star in the galaxy swallowing stars and planets that are not faster than the speed of light so if a black hole moved right next to our earth it would absorb us in). Then we would go to the center of the black hole and get crushed and disappear. Another scenario it’s highly unlikely is ...
... around like a star in the galaxy swallowing stars and planets that are not faster than the speed of light so if a black hole moved right next to our earth it would absorb us in). Then we would go to the center of the black hole and get crushed and disappear. Another scenario it’s highly unlikely is ...
... 3. THE RR LYRAE STARS IN M15 In Clement’s (2002) data base of variables stars, a total of 158 variable stars are known, from which approximately 104 are RR Lyrae type stars. In this work, 33 known RR Lyrae stars, identified in Figs. 1 and 2 and listed in Table 4, have been studied. For all the stars ...
THE FINAL FATE OF STARS THAT IGNITE NEON AND OXYGEN
... Differences in the pre-supernova structures of electron capture supernova (EC-SN) and iron core-collapse supernova (FeCCSN) progenitors, and hence the dynamics of the SN explosion itself, are postulated to be responsible for a number of observed phenomena. These phenomena include the orbital eccentr ...
... Differences in the pre-supernova structures of electron capture supernova (EC-SN) and iron core-collapse supernova (FeCCSN) progenitors, and hence the dynamics of the SN explosion itself, are postulated to be responsible for a number of observed phenomena. These phenomena include the orbital eccentr ...
positive charge and negative charge. Positive charge a
... As most of each atom is empty space, most alpha-particles go through the atoms in the thin foil un-deflected. However, as the nucleus is much smaller than the whole atom, a very small number of alpha-particles incidentally go near the nucleus, and are deflected significantly due to the Coulomb forc ...
... As most of each atom is empty space, most alpha-particles go through the atoms in the thin foil un-deflected. However, as the nucleus is much smaller than the whole atom, a very small number of alpha-particles incidentally go near the nucleus, and are deflected significantly due to the Coulomb forc ...
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.