Using AO to Measure the Star Formation Histories of Massive Galaxies
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Big Dipper’s Binary Star Has Surprises
... planets around nearby stars, but his attention is not completely off Alcor and Mizar. “Some of us have a feeling that Alcor might actually have another surprise in store for us,” he says. —Jonathan Sherwood ’04 (MA), ’09S (MBA) ...
... planets around nearby stars, but his attention is not completely off Alcor and Mizar. “Some of us have a feeling that Alcor might actually have another surprise in store for us,” he says. —Jonathan Sherwood ’04 (MA), ’09S (MBA) ...
Aldebaran
... Aldebaran started off as a large, relatively cool mass of gas, part of a nebula. As gravity caused the gas to contract, its temperature rose, eventually becoming high enough to trigger a nuclear reaction in its atoms. When the gases and dust of the nebula contracted, a protostar was formed. Gravity ...
... Aldebaran started off as a large, relatively cool mass of gas, part of a nebula. As gravity caused the gas to contract, its temperature rose, eventually becoming high enough to trigger a nuclear reaction in its atoms. When the gases and dust of the nebula contracted, a protostar was formed. Gravity ...
1 solar and stellar abundances of the elements
... dusters, such as Messier 67, are much older. They contain no luminous stars; in fact, all stars much more massive than the sun have passed on to more advanced stages of their evolution. As a star ages, the hydrogen in its central regions becomes converted into helium until eventually all the energy ...
... dusters, such as Messier 67, are much older. They contain no luminous stars; in fact, all stars much more massive than the sun have passed on to more advanced stages of their evolution. As a star ages, the hydrogen in its central regions becomes converted into helium until eventually all the energy ...
P7 Further Physics : Observing the Universe
... using the Hertzsprung–Russell diagram, the final topic shows how the internal structure of mainsequence stars is modelled, and then describes protostars and how stars of different masses die. ...
... using the Hertzsprung–Russell diagram, the final topic shows how the internal structure of mainsequence stars is modelled, and then describes protostars and how stars of different masses die. ...
Stellar Spectroscopy during Exoplanet Transits
... Line profile changes during exoplanet transit. Red: Ratios of line profiles relative to the profile outside transit. This simulation sequence from a CO5BOLD model predicts the behavior of an Fe I line ( 620 nm, = 3 eV) during the first half of a transit across the stellar equator by a bloated Jup ...
... Line profile changes during exoplanet transit. Red: Ratios of line profiles relative to the profile outside transit. This simulation sequence from a CO5BOLD model predicts the behavior of an Fe I line ( 620 nm, = 3 eV) during the first half of a transit across the stellar equator by a bloated Jup ...
US - Real Science
... swallowed a small companion in its past. So what caused the asymmetry and the stellar baby boom? Most of the star formation is taking place in dense gassy regions scattered around the arms. But astronomers simply do not know what is compressing this gas so much that stars are forming at a staggerin ...
... swallowed a small companion in its past. So what caused the asymmetry and the stellar baby boom? Most of the star formation is taking place in dense gassy regions scattered around the arms. But astronomers simply do not know what is compressing this gas so much that stars are forming at a staggerin ...
PPT presentation
... variables tells you which stars are now dying. Mass loss rates are sensitive to a combination of R, L, and M such that low metallicity stars, smaller at a given L, M, reach higher L before dying. The generation of dust and oxygen- or carbon-rich molecules further enhances mass loss rates for high Z ...
... variables tells you which stars are now dying. Mass loss rates are sensitive to a combination of R, L, and M such that low metallicity stars, smaller at a given L, M, reach higher L before dying. The generation of dust and oxygen- or carbon-rich molecules further enhances mass loss rates for high Z ...
Life on Our Evolving Planet slides
... The National Academy of Sciences says that it is the role of science to provide plausible natural explanations of natural phenomena. The ultimate question for Earth System History is: How did a giant cloud of cold dilute gas and dust evolve into astronauts in a spacecraft orbiting a planet orbiting ...
... The National Academy of Sciences says that it is the role of science to provide plausible natural explanations of natural phenomena. The ultimate question for Earth System History is: How did a giant cloud of cold dilute gas and dust evolve into astronauts in a spacecraft orbiting a planet orbiting ...
Complex Processes in Simple Ices
... slow otherwise. Chapter 7 and 8 shows, however, that UV desorption is equally efficient for carbon monoxide, which is not dissociated by the UV rays, as for carbon dioxide, which is. Water and methanol ice are also efficiently UV evaporated (Chapter 9–10). With all major ice species having such high ...
... slow otherwise. Chapter 7 and 8 shows, however, that UV desorption is equally efficient for carbon monoxide, which is not dissociated by the UV rays, as for carbon dioxide, which is. Water and methanol ice are also efficiently UV evaporated (Chapter 9–10). With all major ice species having such high ...
Document
... Total Angular momentum almost conserved • These orbits can be thought of as being planar with more or less fixed eccentricity. • The approximate orbital planes have a fixed inclination to the z axis but they process about this axis. • star picks up angular momentum as it goes towards the plane and ...
... Total Angular momentum almost conserved • These orbits can be thought of as being planar with more or less fixed eccentricity. • The approximate orbital planes have a fixed inclination to the z axis but they process about this axis. • star picks up angular momentum as it goes towards the plane and ...
present
... are a lot of myths about this constellation. The Greeks say that Zeus was in love with Callisto. When his wife, Hera, found out, she turned Callisto into a bear. Zeus put her in the sky with her son Arcas, who is the Little Bear. Some Native Americans thought the bear was being chased by three hunte ...
... are a lot of myths about this constellation. The Greeks say that Zeus was in love with Callisto. When his wife, Hera, found out, she turned Callisto into a bear. Zeus put her in the sky with her son Arcas, who is the Little Bear. Some Native Americans thought the bear was being chased by three hunte ...
a High-Mass Protostar with a Rotating Disk.
... the disk (Fig 2), we have not found any evidence for more than one active star formation center in the NGC 7538 S cloud core. The DCN map shows a secondary peak 600 to the northwest of the protostar (at Vlsr ∼ −59 km s−1 ), which is also evident in the continuum map. However, whether this is a separ ...
... the disk (Fig 2), we have not found any evidence for more than one active star formation center in the NGC 7538 S cloud core. The DCN map shows a secondary peak 600 to the northwest of the protostar (at Vlsr ∼ −59 km s−1 ), which is also evident in the continuum map. However, whether this is a separ ...
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.