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Astronomy 102, Spring 2003 Solutions to Review Problems
Astronomy 102, Spring 2003 Solutions to Review Problems

... other. (It’s a different matter in the cores of globular clusters, and even right at the center of our galaxy, but consider the Solar neighborhood for now.) Thus, if there is a binary star system, almost certainly the stars formed together, as it is very unlikely that they would have come across eac ...
Measuring the Milky Way
Measuring the Milky Way

... These objects are very close to the Galactic center. The orbit on the right is the best fit; it assumes a central black hole of 3.7 million solar masses. ...
A Chandra Observation of the Massive Star-Forming
A Chandra Observation of the Massive Star-Forming

... XLFs constructed from hard band luminosities and total luminosities the ACIS-I FOV compared to those (449) detected in X-ray (uncorrected for absorption) compared with Orion XLF from COUP Three color composite MSX image of NGC 6357. Central cavity and bright nebulosities are clearly seen. ...
Supernovae Gamma-Ray Bursts and and some of their uses
Supernovae Gamma-Ray Bursts and and some of their uses

... • The gaseous shell ejected by a supernova plows into the surrounding interstellar medium at V > 104 km/s, compresses it, intermingles with it, enriches it with freshly synthesized heavy elements, and forms what is called a supernova remnant • Supernova remnants may be observed for hundreds of thous ...
Phobos
Phobos

... Large Telescope on Paranal. Those follow-up observations confirmed that both objects are young, at the same distance, and much too cool to be stars. From theoretical models, the astronomers estimate that they have about 14 and 7 times the mass of Jupiter. The newborn pair, barely a million years old ...
File - Mr. Pelton Science
File - Mr. Pelton Science

... • Galaxy clusters larger than the Local Group may have hundreds or thousands of members with diameters up to 30 million ly across. • Galaxies close together often collide to form strangely shaped galaxies or galaxies with more than one nucleus (Andromeda) ...
Protogalaxies Encyclopedia of Astronomy & Astrophysics eaa.iop.org S G Djorgovski
Protogalaxies Encyclopedia of Astronomy & Astrophysics eaa.iop.org S G Djorgovski

... with most of the stars already formed in the merging units and some formed in merger-induced starbursts. It is likely that there was a full spectrum of galaxy assembly scenarios or formation histories at work. The interplay of mass assembly and star formation fundamentally determines the galaxy morp ...
Spiral shock triggering of star formation
Spiral shock triggering of star formation

... •Local dissipation of turbulence •Star formation • SF involves ~10% of mass ...
The Milky Way By
The Milky Way By

... the Local Fluff inside the Local Bubble, and in the Gould Belt, at a distance of 7.62±0.32 kpc (~25,000±1,000 ly) from the Galactic Center. Padurariu Cristian & Danciu Serban ...
Protogalaxies
Protogalaxies

... with most of the stars already formed in the merging units and some formed in merger-induced starbursts. It is likely that there was a full spectrum of galaxy assembly scenarios or formation histories at work. The interplay of mass assembly and star formation fundamentally determines the galaxy morp ...
Elliptical galaxies
Elliptical galaxies

... Projections of the FP onto different ...
Sample Midterm - IUPUI Physics
Sample Midterm - IUPUI Physics

... b) the CNO cycle is so highly temperature dependant that only the large stars can effectively do it c) small stars are just more efficient in the fusion process d) small stars have very large convective zones while large stars are mostly a large radiative zone 20. Fusion can occur in the core of the ...
pptx
pptx

... more hydrogen to power nuclear fusion But it is 10000 times as bright Therefore it should use up its fuel 1000 times more quickly ...
lecture11
lecture11

... l0 = 656 nm Assume, we observe a star’s spectrum with the Ha line at l = 658 nm. Then, Dl = 2 nm. ...
star map looking north january-march
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... Our nearest large galaxy – Andromeda – can be seen in the Andromeda constellation. It appears to us as an elongated fuzzy blob. The Andromeda galaxy is so far away that its light takes over two million years to reach us. ...
The Classification of Stellar Spectra
The Classification of Stellar Spectra

... massive core is physically smaller. The gravity experienced by overlying layers is hence stronger, requiring higher luminosities to maintain the balance between pressure and gravity. Thus the star expends energy at a very high rate and may well become a red supergiant. Stars in this phase of stellar ...
the stars
the stars

... Stars have different colors and luminosities. Following this tutorial we will learn what star luminosity and color are, and which information about stellar evolution we can obtain from them. 2 Stars: magnitude and color Looking at the sky with naked eye most stars appear of the same color. We see st ...
Red Supergiants as Cosmic Abundance Probes
Red Supergiants as Cosmic Abundance Probes

... abundance of the element. Unfortunately, these auroral lines are often very weak, especially at high metallicity. This means that one must attempt to derive abundances based on only the strong emission lines (e.g., [O III] 500.7 nm), which contain no temperature information on their own, by calibrat ...
4P38.pdf
4P38.pdf

... atmosphere and raises the temperature of the most external layer (exosphere). For high radiation inputs, thermal (Jeans) escape of the atmospheric constituents (most notably H, which drags away also heavier atoms), although usually neglected in the Solar System, becomes important. Stars around solar ...
Lecture Notes
Lecture Notes

... (2) Non-thermal (synchrotron) emission with excess energy at UV, IR, radio and X-ray wavelengths. (3) Variability over time-scales from few hours to few years – indicates emitting region is few light years across. (4) Often have jets emerging from nucleus. (5) Have emission line spectra. Examples ar ...
2016 Spring, VAS Newsletter
2016 Spring, VAS Newsletter

... sun's mass, it's going to be much fainter. In most instances, the clumps of matter within will grow slowly, the neutral matter will block more light than it reflects or emits, and only a tiny fraction of the stars that form—the most massive, brightest ones—will be visible at all. Between just 400 an ...
ppt
ppt

... • Every output class needs substantial representation in the training set. • Overlap between classes should be minimized. • Classifier accuracy can be improved with additional information (i.e., flux in different bandpass), but not always! ...
Still Lost in Space
Still Lost in Space

...  Could all these “stars” be basically the same type of object, only lying at different distances?  Perhaps they are extremely compact emission-line nebulae. Normally any nebula would emit multiple lines, but perhaps these nebulae contain only one element, and very unusual excitation mechanisms, so ...
Star Formation and Feedback II: The IMF and the SFR
Star Formation and Feedback II: The IMF and the SFR

... Figure 3. Total gas star formation law in the SMC. The gray scale shows the two-dimensional distribution of the correlation between ΣSFR and Σgas , where Σgas is the surface density of atomic plus molecular gas corrected by helium. The white contours indicate the correlation due to atomic gas alone, ...
pres
pres

... Radial distribution of the hot gas fraction fg in clusters The abscissa is the mean density in radius r, normalised to the critical density (Sadat & Blanchard 2001) ...
< 1 ... 86 87 88 89 90 91 92 93 94 ... 194 >

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.
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