Magnetic susceptibility, magnetization, magnetic moment and
... some cases, intensity ratios are very sensitive to both T e and ne . In this case, two or more diagnostics must be used at the same time to ...
... some cases, intensity ratios are very sensitive to both T e and ne . In this case, two or more diagnostics must be used at the same time to ...
Facilitator`s Guide
... Variable Stars, Type Ia Supernovae The process of “measuring” the stars and the distance to them is a combination of direct measurement, inference and indirect measurement. All direct measurements of stars, and the only measurements that can be made, involve the detection of the energy they emit (ty ...
... Variable Stars, Type Ia Supernovae The process of “measuring” the stars and the distance to them is a combination of direct measurement, inference and indirect measurement. All direct measurements of stars, and the only measurements that can be made, involve the detection of the energy they emit (ty ...
Life Histories Of Some Stars
... 5. Give each group the list of stars attached and the HR diagram attached. Instead of height and weight, the information is in Luminosity (compared to sun) and Surface Temperature (in K). The chart also gives the star’s current status as either a main sequence star* (adulthood for stars), a giant (b ...
... 5. Give each group the list of stars attached and the HR diagram attached. Instead of height and weight, the information is in Luminosity (compared to sun) and Surface Temperature (in K). The chart also gives the star’s current status as either a main sequence star* (adulthood for stars), a giant (b ...
Lithium abundances for 185 main-sequence stars
... 1997) as described by Chen et al. (2000). For the more distant stars we adopt a spectroscopic gravity obtained by requiring that Fe i and Fe ii lines provide the same iron abundance. Metallicities were taken from Chen et al. (2000), Nissen & Schuster (1997), and Edvardsson et al. (1993). For a few s ...
... 1997) as described by Chen et al. (2000). For the more distant stars we adopt a spectroscopic gravity obtained by requiring that Fe i and Fe ii lines provide the same iron abundance. Metallicities were taken from Chen et al. (2000), Nissen & Schuster (1997), and Edvardsson et al. (1993). For a few s ...
Black Hole`` Systems.`
... A rotating intrinsic magnetic field (shown in pale yellow) anchored to the MECO generates a magnetic propeller, sweeping out a large region (shown in black) of the inner accretion disk. The magnetic propeller also creates radial outflows of atomic nuclei (shown in indigo blue) and relativistic j ...
... A rotating intrinsic magnetic field (shown in pale yellow) anchored to the MECO generates a magnetic propeller, sweeping out a large region (shown in black) of the inner accretion disk. The magnetic propeller also creates radial outflows of atomic nuclei (shown in indigo blue) and relativistic j ...
The Chemical Composition of Carbon-Rich, Very Metal
... of Beers, Preston & Shectman 1992; Beers 1999), which have identified objects as metal-poor as [Fe/H]= −4 5 . One unexpected result of the HK survey is that many (∼ 10-15%) of the most metal-poor stars exhibit anomalously strong CH bands, most easily understood in terms of an excess of carbon in the ...
... of Beers, Preston & Shectman 1992; Beers 1999), which have identified objects as metal-poor as [Fe/H]= −4 5 . One unexpected result of the HK survey is that many (∼ 10-15%) of the most metal-poor stars exhibit anomalously strong CH bands, most easily understood in terms of an excess of carbon in the ...
Chemical tagging of three distinct populations of red giants in the
... a prolonged phase of 3rd-dredge up, likely resulting in enhanced C and s−elements, which is not observed in NGC 6752 (James et al. 2004). On the other hand, models of 5 M⊙ stars at the metallicity of NGC 6752 do yield abundances [Al/Fe]∼ 1.2 dex, not very far away from the observed maximum, but they ...
... a prolonged phase of 3rd-dredge up, likely resulting in enhanced C and s−elements, which is not observed in NGC 6752 (James et al. 2004). On the other hand, models of 5 M⊙ stars at the metallicity of NGC 6752 do yield abundances [Al/Fe]∼ 1.2 dex, not very far away from the observed maximum, but they ...
Exploring the Universe
... – Hottest stars are blue, coolest are red – Hertzspurg-Russel diagram classifies stars • 90° of stars are called the main sequence • Other stars include red giants, supergiants, and dwarfs ...
... – Hottest stars are blue, coolest are red – Hertzspurg-Russel diagram classifies stars • 90° of stars are called the main sequence • Other stars include red giants, supergiants, and dwarfs ...
Homework #3, AST 1002
... (a) All pulsars are neutron stars. (b) Pulsars pulse at a very constant rate. (c) The Crab pulsar has a period of less than one second. The correct answer(s) is(are) ____________. ...
... (a) All pulsars are neutron stars. (b) Pulsars pulse at a very constant rate. (c) The Crab pulsar has a period of less than one second. The correct answer(s) is(are) ____________. ...
ppt - IASF Milano
... rvir (Bullock et al. 2001, B01; Dolag et al. 2004, D04). Navarro et al. 2004 ...
... rvir (Bullock et al. 2001, B01; Dolag et al. 2004, D04). Navarro et al. 2004 ...
Document
... • 1800 Friedrich von Hahn discovers central star of Ring Nebula (very faint) • Central Stars have Hydrogen, Helium and sometimes Carbon & Oxygen lines. • 1918 Wright identifies as type “O” [VERY HOT 125,000 C], hence must be very very small to be so faint! ...
... • 1800 Friedrich von Hahn discovers central star of Ring Nebula (very faint) • Central Stars have Hydrogen, Helium and sometimes Carbon & Oxygen lines. • 1918 Wright identifies as type “O” [VERY HOT 125,000 C], hence must be very very small to be so faint! ...
The first gravitational-wave source from the isolated evolution of two
... magnitude larger than the rate estimate from LIGO. This implies that unevolved massive stars (during main sequence and Hertzsprung gap) do not initiate/survive CE (9, 24). In our classical BH-BH formation scheme only evolved stars (during core helium burning) with well-developed convective envelopes ...
... magnitude larger than the rate estimate from LIGO. This implies that unevolved massive stars (during main sequence and Hertzsprung gap) do not initiate/survive CE (9, 24). In our classical BH-BH formation scheme only evolved stars (during core helium burning) with well-developed convective envelopes ...
The Chandra Orion Ultradeep Project Eric Feigelson
... Some (but not all) flare loops are longer than seen in other stars, perhaps extending to the disk ...
... Some (but not all) flare loops are longer than seen in other stars, perhaps extending to the disk ...
All About Elements
... in the universe. Only Hydrogen is more abundant! These two elements were copiously formed during the creation of the universe. In the early stages of the universe, helium and hydrogen nuclei were actually formed. No atoms were formed until about 300,000 years after the Big Bang took place, when the ...
... in the universe. Only Hydrogen is more abundant! These two elements were copiously formed during the creation of the universe. In the early stages of the universe, helium and hydrogen nuclei were actually formed. No atoms were formed until about 300,000 years after the Big Bang took place, when the ...
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.