Galaxy Spiral Arms
... perspective. Think of any galaxy spiral arm as a very large and massive “open cluster” of stars. We all accept that open clusters have a structural integrity due to mutual gravitation, even while revolving with the galaxy as a whole. We all believe that the Pleiades Cluster stays together due to mut ...
... perspective. Think of any galaxy spiral arm as a very large and massive “open cluster” of stars. We all accept that open clusters have a structural integrity due to mutual gravitation, even while revolving with the galaxy as a whole. We all believe that the Pleiades Cluster stays together due to mut ...
Heavy Element Abundances in Late-B and Early
... Unfortunately, the results from IUE data are constrained by their limited signal-to-noise ratio (S/ N ) (seldom more than 40:1 even for the very best co-added data) and limited resolution (k=k 12000). For a small number of CP stars, observations made with the Hubble Space Telescope’s Goddard High ...
... Unfortunately, the results from IUE data are constrained by their limited signal-to-noise ratio (S/ N ) (seldom more than 40:1 even for the very best co-added data) and limited resolution (k=k 12000). For a small number of CP stars, observations made with the Hubble Space Telescope’s Goddard High ...
Is $^ 6$ Li in metal-poor halo stars produced in situ by solar
... We also assume that the rate of proton acceleration in stellar flares does not depend on metallicity, but only on surface magnetic flux. In solar flares, the particle acceleration processes at work in impulsive events are related to excitation of plasma waves that are essentially independent of the ...
... We also assume that the rate of proton acceleration in stellar flares does not depend on metallicity, but only on surface magnetic flux. In solar flares, the particle acceleration processes at work in impulsive events are related to excitation of plasma waves that are essentially independent of the ...
Global structure and kinematics of stellar haloes in cosmological
... hybrid methods. Finally, hybrid models appear to overproduce the degree of substructure seen in the stellar halo of the Milky Way (e.g., Helmi et al. 2011; Xue et al. 2011). Hybrid models implicitly assume that the spheroid is built entirely of the tidal disruption of infalling satellites, they do n ...
... hybrid methods. Finally, hybrid models appear to overproduce the degree of substructure seen in the stellar halo of the Milky Way (e.g., Helmi et al. 2011; Xue et al. 2011). Hybrid models implicitly assume that the spheroid is built entirely of the tidal disruption of infalling satellites, they do n ...
Magnetic cycles of Sun-like stars with different levels of coronal and
... program of observations of Sun-like stars (see Baliunas et al. 1995; Lockwood et al. 2007). One of the most important results of the HK-project was the discovery of ”11-yr” cycles of activity in Sun-like stars. Durations of CA cycles, found for 50 different stars of late spectral classes (F, G and K ...
... program of observations of Sun-like stars (see Baliunas et al. 1995; Lockwood et al. 2007). One of the most important results of the HK-project was the discovery of ”11-yr” cycles of activity in Sun-like stars. Durations of CA cycles, found for 50 different stars of late spectral classes (F, G and K ...
Magnificent Cosmos - Academic Program Pages at Evergreen
... ORION NEBULA (left), a turbulent maelstrom of luminous gas and brilliant stars, shows stellar formation under way. Located 1,500 lightyears from Earth in the Milky Way’s spiral arm, the nebula formed from collapsing interstellar gas clouds, yielding many hot, young stars. Among those are at least 15 ...
... ORION NEBULA (left), a turbulent maelstrom of luminous gas and brilliant stars, shows stellar formation under way. Located 1,500 lightyears from Earth in the Milky Way’s spiral arm, the nebula formed from collapsing interstellar gas clouds, yielding many hot, young stars. Among those are at least 15 ...
A GMOS dissection of the line-of
... Our observations show that there is no large cluster in front of the quasar, but rather several smaller groups at different redshifts. Hard to tell if there is strong magnification present from current data. Statistical properties of high-z radio quasars may be more useful in determining importance ...
... Our observations show that there is no large cluster in front of the quasar, but rather several smaller groups at different redshifts. Hard to tell if there is strong magnification present from current data. Statistical properties of high-z radio quasars may be more useful in determining importance ...
The SMC as a probe of dust in the early Universe
... Evolved Stars — Previous samples in the SMC have concentrated on evolved stars, are dominated by carbon stars, and have left some critical holes. Stars in clusters are particularly important, because they have known metallicities and ages (and therefore masses on the AGB). Supergiants contribute ∼10 ...
... Evolved Stars — Previous samples in the SMC have concentrated on evolved stars, are dominated by carbon stars, and have left some critical holes. Stars in clusters are particularly important, because they have known metallicities and ages (and therefore masses on the AGB). Supergiants contribute ∼10 ...
The chemical composition of two supergiants in the dwarf
... globular cluster space velocities are not known. The distance to WLM puts the tip of the red giant branch at V ∼ 22, which is out of reach for detailed chemical abundance analyses of its RGB population. However, there are bright blue supergiants in WLM’s central star forming region with V ∼ 18. Thes ...
... globular cluster space velocities are not known. The distance to WLM puts the tip of the red giant branch at V ∼ 22, which is out of reach for detailed chemical abundance analyses of its RGB population. However, there are bright blue supergiants in WLM’s central star forming region with V ∼ 18. Thes ...
LOOKING INTO THE HORSEHEAD Marc W. Pound Bo Reipurth and
... Horsehead got the name B33 by which it is known today. The first indication that the IC 434 and Horsehead region could be related to young stars came with the discovery of H emission line stars in the general area by Haro & Moreno (1953), followed by the detection of variable stars in the same regio ...
... Horsehead got the name B33 by which it is known today. The first indication that the IC 434 and Horsehead region could be related to young stars came with the discovery of H emission line stars in the general area by Haro & Moreno (1953), followed by the detection of variable stars in the same regio ...
Dynamical properties of a large young disk galaxy at z=2.03⋆
... (K= 19.7 − 21.1) and have large stellar masses (M > 1011 M⊙ ). They constitute half of the most rest-frame luminous galaxies (LV > 6 × 1010 h−2 70 L⊙ ) and their number density exceeds model predictions (e.g., Mo et al., 1998) by a factor of two. Obviously, the first and foremost question that needs ...
... (K= 19.7 − 21.1) and have large stellar masses (M > 1011 M⊙ ). They constitute half of the most rest-frame luminous galaxies (LV > 6 × 1010 h−2 70 L⊙ ) and their number density exceeds model predictions (e.g., Mo et al., 1998) by a factor of two. Obviously, the first and foremost question that needs ...
Galactic astroarchaeology: reconstructing the bulge history by
... solar vicinity (∼–1.0). For spiral and irregular instead, the Fe enrichment by core collapse SNe is much less, due to the milder SFR, and the [Fe/H] is still low when type Ia SNe start appearing. Thus the change in slope in irregulars occurs at [Fe/H] ≤–2.0 (see Matteucci 2001). Years later, McWilli ...
... solar vicinity (∼–1.0). For spiral and irregular instead, the Fe enrichment by core collapse SNe is much less, due to the milder SFR, and the [Fe/H] is still low when type Ia SNe start appearing. Thus the change in slope in irregulars occurs at [Fe/H] ≤–2.0 (see Matteucci 2001). Years later, McWilli ...
Dust and molecular gas in the most distant quasars
... • It is likely that active star formation is ongoing in the host galaxies of the strong millimeter detected quasars at z~6. – Star formation rate: ≥103 Msun yr-1. – Star formation efficiency: comparable to ULIRGs and SMGs. • Gas mass: ~1010 Msun, which will turn to stars via the massive starburst. • ...
... • It is likely that active star formation is ongoing in the host galaxies of the strong millimeter detected quasars at z~6. – Star formation rate: ≥103 Msun yr-1. – Star formation efficiency: comparable to ULIRGs and SMGs. • Gas mass: ~1010 Msun, which will turn to stars via the massive starburst. • ...
Word version - White dwarf stars and the Chandrasekhar limit
... During the beginning of his second year of honors studies Arnold Sommerfeld came to Presidency college to give a lecture. Chandra spoke to Sommerfeld after the lecture, and was informed that much of the physics he had learned had been changed by new developments due to Heisenberg, Dirac, Pauli, and ...
... During the beginning of his second year of honors studies Arnold Sommerfeld came to Presidency college to give a lecture. Chandra spoke to Sommerfeld after the lecture, and was informed that much of the physics he had learned had been changed by new developments due to Heisenberg, Dirac, Pauli, and ...
The Young Stars
... displayed erratic optical variability, strong chromospheric lines and could be identified through their strong Hα emission lines. They were found to congregate at the periphery of dark clouds. The nearest were located in the Taurus molecular cloud and the ρ Ophiuchus cloud. Given our present knowled ...
... displayed erratic optical variability, strong chromospheric lines and could be identified through their strong Hα emission lines. They were found to congregate at the periphery of dark clouds. The nearest were located in the Taurus molecular cloud and the ρ Ophiuchus cloud. Given our present knowled ...
The Oort cloud as a remnant of the protosolar nebula
... idea of interstellar cloud comet origin has already been proposed by several authors (omitting the theories which have been rejected, e.g. that by Lyttleton (1948), we can mention for example: Hasegawa (1976), Khanna & Sharma (1983), Yabushita (1985) or Greenberg (1998)). A particular argument in fa ...
... idea of interstellar cloud comet origin has already been proposed by several authors (omitting the theories which have been rejected, e.g. that by Lyttleton (1948), we can mention for example: Hasegawa (1976), Khanna & Sharma (1983), Yabushita (1985) or Greenberg (1998)). A particular argument in fa ...
There are 88 constellations in the sky around the Earth. 12 are the
... became a popular sport of kings and a necessity to keep their populations down. The lion is associated with the warrior goddess, Istar. Representations of the hero-king Gilgamesh often show him with a club in one hand and a lion in the other. The sickle shape of the constellation containing the bri ...
... became a popular sport of kings and a necessity to keep their populations down. The lion is associated with the warrior goddess, Istar. Representations of the hero-king Gilgamesh often show him with a club in one hand and a lion in the other. The sickle shape of the constellation containing the bri ...
1 The Hubble Story (10:56)
... With ground-based telescopes the gas giant planet HD 209458b, 150 light-years from Earth, was discovered in 1999 through its slight gravitational tug on its ‘mother-star’. In 2001 Hubble made highly accurate measurements of the dip in the star’s light when the planet passed in front. The first detec ...
... With ground-based telescopes the gas giant planet HD 209458b, 150 light-years from Earth, was discovered in 1999 through its slight gravitational tug on its ‘mother-star’. In 2001 Hubble made highly accurate measurements of the dip in the star’s light when the planet passed in front. The first detec ...
SUB-KILOPARSEC IMAGING OF COOL MOLECULAR GAS IN
... of three CO lines in two high-redshift gravitationally lensed dusty star-forming galaxies, discovered by the South Pole Telescope. Strong lensing allows us to probe the structure and dynamics of the molecular gas in these two objects, at z = 2.78 and z = 5.66, with effective source-plane resolution ...
... of three CO lines in two high-redshift gravitationally lensed dusty star-forming galaxies, discovered by the South Pole Telescope. Strong lensing allows us to probe the structure and dynamics of the molecular gas in these two objects, at z = 2.78 and z = 5.66, with effective source-plane resolution ...
Molecular cloud regulated star formation in galaxies
... However, simulations show that the energy contained in supersonic motions is quickly dissipated even in the presence of magnetic fields (see references in Mac Low & Klessen 2004). To sustain the turbulence therefore requires an energy source, for example, from star formation, yet some clouds have tu ...
... However, simulations show that the energy contained in supersonic motions is quickly dissipated even in the presence of magnetic fields (see references in Mac Low & Klessen 2004). To sustain the turbulence therefore requires an energy source, for example, from star formation, yet some clouds have tu ...
Nucleosynthesis and Chemical Evolution of Oxygen
... To analyze the yields from massive stars, we consider a single model. While this is only one particular model, its yields are fairly representative of the ejecta from any star more than ten times the mass of the Sun. Chemical evolution models using detailed stellar model yields have long shown that ...
... To analyze the yields from massive stars, we consider a single model. While this is only one particular model, its yields are fairly representative of the ejecta from any star more than ten times the mass of the Sun. Chemical evolution models using detailed stellar model yields have long shown that ...
Riccioli Measures the Stars: Observations of the
... diameters; he refers the reader to Book 6 Chapter IX for discussion of the diameters of stars and planets and their measurement. He and Grimaldi record the shape of Jupiter‟s disk and Saturn‟s oval form, emphasizing that they can do this with accuracy by means of repeated and immediate comparisons b ...
... diameters; he refers the reader to Book 6 Chapter IX for discussion of the diameters of stars and planets and their measurement. He and Grimaldi record the shape of Jupiter‟s disk and Saturn‟s oval form, emphasizing that they can do this with accuracy by means of repeated and immediate comparisons b ...
Quantitative constraints on starburst cycles in galaxies with stellar
... galaxies. High mass galaxies with large burst mass fractions are more centrally concentrated, indicating that bulge formation is at work. In low mass galaxies, stellar surface densities µ∗ decrease as a function of Fburst . These results are in good agreement with the observational predictions of Te ...
... galaxies. High mass galaxies with large burst mass fractions are more centrally concentrated, indicating that bulge formation is at work. In low mass galaxies, stellar surface densities µ∗ decrease as a function of Fburst . These results are in good agreement with the observational predictions of Te ...
Deep Sky Catalogues, the New Uranometria and Other Stories
... Prior to the publication of the new Uranometria, Murray Cragin reported on the U.S. mailing list „amastro“ about the quality of the database (DSFG) and the involved experts. As some of my project colleagues are mentioned, I was first convinced that our work hab been taken into account. However, I wa ...
... Prior to the publication of the new Uranometria, Murray Cragin reported on the U.S. mailing list „amastro“ about the quality of the database (DSFG) and the involved experts. As some of my project colleagues are mentioned, I was first convinced that our work hab been taken into account. However, I wa ...
H II region
An H II region is a large, low-density cloud of partially ionized gas in which star formation has recently taken place. The short-lived blue stars forged in these regions emit copious amounts of ultraviolet light that ionize the surrounding gas. H II regions—sometimes several hundred light-years across—are often associated with giant molecular clouds. The first known H II region was the Orion Nebula, which was discovered in 1610 by Nicolas-Claude Fabri de Peiresc.H II regions are named for the large amount of ionised atomic hydrogen they contain, referred to as H II, pronounced H-two by astronomers (an H I region being neutral atomic hydrogen, and H2 being molecular hydrogen). Such regions have extremely diverse shapes, because the distribution of the stars and gas inside them is irregular. They often appear clumpy and filamentary, sometimes showing bizarre shapes such as the Horsehead Nebula. H II regions may give birth to thousands of stars over a period of several million years. In the end, supernova explosions and strong stellar winds from the most massive stars in the resulting star cluster will disperse the gases of the H II region, leaving behind a cluster of birthed stars such as the Pleiades.H II regions can be seen to considerable distances in the universe, and the study of extragalactic H II regions is important in determining the distance and chemical composition of other galaxies. Spiral and irregular galaxies contain many H II regions, while elliptical galaxies are almost devoid of them. In the spiral galaxies, including the Milky Way, H II regions are concentrated in the spiral arms, while in the irregular galaxies they are distributed chaotically. Some galaxies contain huge H II regions, which may contain tens of thousands of stars. Examples include the 30 Doradus region in the Large Magellanic Cloud and NGC 604 in the Triangulum Galaxy.