MSci Astrophysics 210PHY412
... Source of energy generation: What is the source of this energy ? Four possibilities : • Cooling or contraction • Chemical Reactions • Nuclear Reactions Cooling and contraction These are closely related, so we consider them together. Cooling is simplest idea of all. Suppose the radiative energy of S ...
... Source of energy generation: What is the source of this energy ? Four possibilities : • Cooling or contraction • Chemical Reactions • Nuclear Reactions Cooling and contraction These are closely related, so we consider them together. Cooling is simplest idea of all. Suppose the radiative energy of S ...
Life in the Solar System and Beyond Best
... • While it is easiest to think about life around a Sun-like star, that doesn't have to be the case • However, there are some stars which make their surroundings quite inhabitable • Some small, red M dwarfs have violent flaring activity • Large, massive O/B stars have strong winds and put out more ul ...
... • While it is easiest to think about life around a Sun-like star, that doesn't have to be the case • However, there are some stars which make their surroundings quite inhabitable • Some small, red M dwarfs have violent flaring activity • Large, massive O/B stars have strong winds and put out more ul ...
Stellar Masses
... • Hubble combined his results with Slipher’s and found a clear correlation between a galaxy’s recessional velocity v and the distance from the Earth d. Note: Most of Hubble’s measurements were actually made by his ...
... • Hubble combined his results with Slipher’s and found a clear correlation between a galaxy’s recessional velocity v and the distance from the Earth d. Note: Most of Hubble’s measurements were actually made by his ...
Unit 6: Space - Galena Park ISD
... levels and surface temperatures among the various types of stars. Hot clouds of gaseous elements and compounds called nebulae serve as nurseries for stars. As these nebulae spin, they slowly condense, raising their temperature and forming stars. Galaxies are made of millions of stars, interstellar g ...
... levels and surface temperatures among the various types of stars. Hot clouds of gaseous elements and compounds called nebulae serve as nurseries for stars. As these nebulae spin, they slowly condense, raising their temperature and forming stars. Galaxies are made of millions of stars, interstellar g ...
Gilmore
... On galaxy scales there is an opportunity to learn some physics: everything should happen late. But. 0: big old galaxies, big old disks, SFR peaks z>1, 1: the MWG has a thick disk, just one of them, and it is old. This seems common. 2: massive old pure-thin-disk galaxies exist. Should they? 3: Sgr in ...
... On galaxy scales there is an opportunity to learn some physics: everything should happen late. But. 0: big old galaxies, big old disks, SFR peaks z>1, 1: the MWG has a thick disk, just one of them, and it is old. This seems common. 2: massive old pure-thin-disk galaxies exist. Should they? 3: Sgr in ...
The Sun: the Solar Atmosphere, Nuclear Fusion
... •The higher the temperature, the larger the number of fusion reactions each second. •Even small Temperature variations cause large variations in the number of fusion reactions ...
... •The higher the temperature, the larger the number of fusion reactions each second. •Even small Temperature variations cause large variations in the number of fusion reactions ...
Full 11x8.5" Calendar, High Resolution - Chandra X
... Sun. Some of this material may eventually be consumed by the black hole, and the magnetized, whirlpool of gas near the black hole could in turn, trigger more output to the radio jet. The optical light image shows the stars in this galaxy. ...
... Sun. Some of this material may eventually be consumed by the black hole, and the magnetized, whirlpool of gas near the black hole could in turn, trigger more output to the radio jet. The optical light image shows the stars in this galaxy. ...
The Formation of Massive Star Systems by Accretion
... these effects because most massive stars are members of multiple systems (12, 13). Our initial conditions consisted of a gas cloud with mass = 100 M⊙, radius = 0.1 pc, and density profile r º r−1.5, consistent with models (14, 15) and observations (16) of the initial states of massive prestellar cor ...
... these effects because most massive stars are members of multiple systems (12, 13). Our initial conditions consisted of a gas cloud with mass = 100 M⊙, radius = 0.1 pc, and density profile r º r−1.5, consistent with models (14, 15) and observations (16) of the initial states of massive prestellar cor ...
Chap4-Timing
... Fate of planetary systems during the red giant phase. All planets within the final extent of the red giant envelope will be engulfed and migrate inwards. Planets further out will have greater chance of survival, migrating outwards as mass is lost from central star. In mass is loss instantane ...
... Fate of planetary systems during the red giant phase. All planets within the final extent of the red giant envelope will be engulfed and migrate inwards. Planets further out will have greater chance of survival, migrating outwards as mass is lost from central star. In mass is loss instantane ...
Massive star evolution: luminous blue variables as unexpected
... LBVs (e.g. Clark et al. 2009). The 25 M model predicts a more chemically enriched surface with He and N (0.92 and 0.016 by mass fraction, respectively) and, as expected, its spectrum shows stronger He I and N II lines than that of the 20 M model or the LBV observations. Still, the 25 M model spec ...
... LBVs (e.g. Clark et al. 2009). The 25 M model predicts a more chemically enriched surface with He and N (0.92 and 0.016 by mass fraction, respectively) and, as expected, its spectrum shows stronger He I and N II lines than that of the 20 M model or the LBV observations. Still, the 25 M model spec ...
Gravitational redshifts
... synthetic line profiles) are shorter than laboratory values due to convective blueshift. Curves before and after mid-transit (µ = 0.21, 0.59, 0.87) are not exact mirror images due to intrinsic stellar line asymmetries. This simulation from a CO5BOLD model predicts the behavior of an Fe I line ( 620 ...
... synthetic line profiles) are shorter than laboratory values due to convective blueshift. Curves before and after mid-transit (µ = 0.21, 0.59, 0.87) are not exact mirror images due to intrinsic stellar line asymmetries. This simulation from a CO5BOLD model predicts the behavior of an Fe I line ( 620 ...
McDonald Observatory Planet Search - tls
... Brunt Väisälä Frequency However if r* < r, the blob is less dense than its surroundings, buoyancy force will cause it to continue to rise Criterion for onset of convection: ...
... Brunt Väisälä Frequency However if r* < r, the blob is less dense than its surroundings, buoyancy force will cause it to continue to rise Criterion for onset of convection: ...
Climbing the Distance Ladder
... We don’t directly measure a star’s luminosity. We measure its flux (f): the wattage collected per square meter of our telescope mirror. ...
... We don’t directly measure a star’s luminosity. We measure its flux (f): the wattage collected per square meter of our telescope mirror. ...
How Bright is that Star?
... A 1st magnitude star is 100x brighter than a “6th ” Each order of magnitude is therefore 2.15 times brighter than the one below it. Magnitude is now given in decimal form. Deneb now rates a 1.26, and Betelgeuse rates .87. Hipparchus underestimated how bright the brightest were, so now we even use ne ...
... A 1st magnitude star is 100x brighter than a “6th ” Each order of magnitude is therefore 2.15 times brighter than the one below it. Magnitude is now given in decimal form. Deneb now rates a 1.26, and Betelgeuse rates .87. Hipparchus underestimated how bright the brightest were, so now we even use ne ...
Double Stars Discovered by IOTA Predicted Occultations July, 2010
... event, with the brighter of the two stars occulted first. A double asteroid is precluded by the fact that the magnitude drops are different between the two events. Two light curves are shown to verify the ‘events’ were not affected by other non-occultation variations. ...
... event, with the brighter of the two stars occulted first. A double asteroid is precluded by the fact that the magnitude drops are different between the two events. Two light curves are shown to verify the ‘events’ were not affected by other non-occultation variations. ...
Sample - Physics @ IUPUI
... • D) stops spinning 11) What are pulsars? • A) rapidly spinning neutron stars • B) rapidly spinning black holes • C) stars that change temperature rapidly • D) stars that change size rapidly 12) Where does the energy that pulsars emit come from? • A) heat • B) fusion • C) gravity • D) spin 13) If we ...
... • D) stops spinning 11) What are pulsars? • A) rapidly spinning neutron stars • B) rapidly spinning black holes • C) stars that change temperature rapidly • D) stars that change size rapidly 12) Where does the energy that pulsars emit come from? • A) heat • B) fusion • C) gravity • D) spin 13) If we ...
X-ray binaries
... formation of BHs the lower mass limit may be even by ~ 10MO higher than indicated. [Postnov, Yungelson 2007] ...
... formation of BHs the lower mass limit may be even by ~ 10MO higher than indicated. [Postnov, Yungelson 2007] ...
White dwarf cooling sequences and cosmochronology
... distributed through all the star [24]. An additional source of energy that has to be taken into account is the gravitational diffusion of 22 Ne synthesized from the initial content of 12 C, 14 N and 16 O during the He-burning phase [25]. Debye cooling: When almost all the star has solidified, the sp ...
... distributed through all the star [24]. An additional source of energy that has to be taken into account is the gravitational diffusion of 22 Ne synthesized from the initial content of 12 C, 14 N and 16 O during the He-burning phase [25]. Debye cooling: When almost all the star has solidified, the sp ...
PowerPoint Presentation - Neutron stars, pulsars and black
... • The discovery of pulsars that were spinning more 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 pu ...
... • The discovery of pulsars that were spinning more 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 pu ...
PHYS3380_111615_bw - The University of Texas at Dallas
... supergiant presumed to have a mass of about 15 - 20 solar masses. - required some revisions to models of high mass stellar evolution, which had suggested that supernovae would result from red supergiants. Now believe star was chemically poor in elements heavier than He - contracted and heated up aft ...
... supergiant presumed to have a mass of about 15 - 20 solar masses. - required some revisions to models of high mass stellar evolution, which had suggested that supernovae would result from red supergiants. Now believe star was chemically poor in elements heavier than He - contracted and heated up aft ...
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.