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EVOLUTION OF THE QUASAR POPULATION AT HIGH REDSHIFT
EVOLUTION OF THE QUASAR POPULATION AT HIGH REDSHIFT

... First I would like to thank my advisor Xiaohui Fan for his guidance, encouragement, and his friendship. He always inspires me to develop independent thinking and research skills, and to collaborate with others in different fields. Without his support, I could not have done my doctoral work. I am gra ...
The Observer`s Guide to the Gamma-Ray Burst
The Observer`s Guide to the Gamma-Ray Burst

... The luminosity, energetics and shape of the γ-ray pulse of a given GRB can reveal clues to the origin of its high-energy emission, and thus its emission process. Of particular importance is whether the γ-rays emitted by llGRBs arise from the same mechanism as high-luminosity GRBs (i.e. from a jet), ...
Lyman-alpha imaging of starburst galaxies in the local universe and beyond Matthew Hayes
Lyman-alpha imaging of starburst galaxies in the local universe and beyond Matthew Hayes

... review can be found in Kennicutt (1998a). For standard initial mass function (IMF; the mass distribution of stars at zero age)1 , the relative abundance of massive stars is small. Since these stars have very short lifetimes (less than the proto-stellar collapse timescale) ongoing star formation is r ...
Leakage of ionizing radiation from the nearby galaxy Tololo 1247
Leakage of ionizing radiation from the nearby galaxy Tololo 1247

the mass distribution and lifetime of prestellar cores in perseus
the mass distribution and lifetime of prestellar cores in perseus

... Ophiuchus. In a companion paper to this work (M. L. Enoch et al. 2008, in preparation), we use the comparison of 1.1 mm and Spitzer data to study the properties of embedded protostars. In particular, we examine the bolometric temperatures and luminosities of Class 0 and Class I protostars in Perseus ...
ASTE Simultaneous HCN(4–3) and HCO+(4–3)
ASTE Simultaneous HCN(4–3) and HCO+(4–3)

Galaxy And Mass Assembly (GAMA): Gas Fuelling of Spiral Galaxies
Galaxy And Mass Assembly (GAMA): Gas Fuelling of Spiral Galaxies

... We quantify the effect of the galaxy group environment (for group masses of 1012.5 to 1014.0 M ) on the current star formation rate (SFR) of a pure, morphologically-selected, sample of disk-dominated (i.e. late-type spiral) galaxies with redshift ≤ 0.13. The sample embraces a full representation of ...
Herschel/PACS spectroscopy of NGC 4418 and Arp 220: H2O
Herschel/PACS spectroscopy of NGC 4418 and Arp 220: H2O

... the comparison indicates that both sources are at far-IR wavelengths point-sources compared with the PACS 9 × 9 spatial resolution (∼1.3 × 1.3 kpc2 for NGC 4418 and ∼3.1 × 3.1 kpc2 for Arp 220). The continua of both sources are shown in Fig. 1, including the Spitzer IRS spectra (Spoon et al. 200 ...
The Evolution of the Mass-Size relation to z = 3.5 in the GOODS
The Evolution of the Mass-Size relation to z = 3.5 in the GOODS

β Relation for Local Galaxies
β Relation for Local Galaxies

... a much lower ratio of the b-parameter compared to starburst galaxies. However, the results of Boquien et al. (2009, 2012), and Siebert et al. (2005) do not support the birthrate parameter result; instead, they suggest that the offset may merely be a result of the difference in dust geometry between ...
Watson et al. 2007a - Department of Physics and Astronomy
Watson et al. 2007a - Department of Physics and Astronomy

... Solar- and later-type young stars, and test the standard models of dust processing which result in the conversion of originally amorphous dust into minerals. We find strong evidence of evolution of the dust crystalline mass fraction in parallel with that of the structure of the disks, in the sense t ...
The 3-D shaping of NGC 6741: a massive, fast
The 3-D shaping of NGC 6741: a massive, fast

Galaxy Formation and Evolution.
Galaxy Formation and Evolution.

... F R A N K VA N D E N B O S C H is Assistant Professor at Yale University, and is known for his studies of the formation, dynamics, and clustering of galaxies. S I M O N W H I T E is Director at the Max Planck Institute for Astrophysics in Garching. He is one of the originators of the modern theory o ...
Galaxies in the Universe: An Introduction, Second Edition
Galaxies in the Universe: An Introduction, Second Edition

Direct Evidence for Termination of Obscured Star Formation by
Direct Evidence for Termination of Obscured Star Formation by

... local to the SMBH can (3) heat gas in the ISM, and/or (4) drive gas out of the galaxy via kinetic pressure. Most discussions of AGN feedback condense the four feedback mechanisms described above into two simplified paradigms; ‘quasar’ mode feedback and ‘radio’ mode feedback. Quasar mode feedback ass ...
The effect of stellar limb darkening values on the accuracy of the
The effect of stellar limb darkening values on the accuracy of the

University of Groningen Late-type spiral galaxies Ganda, Katia
University of Groningen Late-type spiral galaxies Ganda, Katia

... 2005) mainly refers to the emission-line properties, to the characteristics of the HII regions or to the nature of the innermost component. In particular, no study has addressed yet in a systematic way the stellar populations of late-type spiral galaxies with a two-dimensional coverage. Existing stu ...
submillimeter observations of giant molecular clouds in the large
submillimeter observations of giant molecular clouds in the large

... regions N158C, N159, and N160 with a few prominent CO clouds in the J ¼ 2Y1 and J ¼ 3Y2 transitions of CO. They find that the kinetic temperatures are 10Y80 K and the highest temperature is toward 30 Dor. The smallest beam size and grid spacing are 1500 and 1100 , respectively, in the J ¼ 3Y2 emissi ...
HUBBLE SPACE TELESCOPE AND GROUND-BASED
HUBBLE SPACE TELESCOPE AND GROUND-BASED

http://arxiv.org/pdf/1401.1510v1.pdf
http://arxiv.org/pdf/1401.1510v1.pdf

... The flux-limited sub-mm selection ensures a relatively homogenous sample of the most intensely starforming dust obscured galaxies at z & 3: Due to the negative kcorrection, the sub-mm flux detection limit corresponds roughly to a cut in SFR over the considered redshift range. Note that while a fract ...
Modeling Spatially and Spectrally Resolved Observations to
Modeling Spatially and Spectrally Resolved Observations to

... This thesis owes much to the support of my officemate, Zach Berta, for five years of advice on life, computers, and astronomy. I thank Diego Muñoz, Robert Harris, Ragnhild Lunnan, and Sarah Rugheimer for countless snack and coffee breaks; Wen-fai Fong and Nick Stone for leading camping trips and t ...
Constraints on the physical properties and chemical evolution of star
Constraints on the physical properties and chemical evolution of star

... constrain the physical properties and chemical enrichment of the gas in galaxies at all cosmic epochs. This is important, because galaxies are being detected at always higher redshift and upcoming observations with large telescopes, such as the James Webb Space Telescope, will gather high-quality sp ...
Galaxy Evolution Over the Past Eleven Billion Years: Mergers and
Galaxy Evolution Over the Past Eleven Billion Years: Mergers and

The 3-D shaping of NGC 6741: A massive, fast
The 3-D shaping of NGC 6741: A massive, fast

... surrounded by a sharp low-excitation skin (the ionization front), and embedded in a spherical (radius  0.080 pc), almostneutral, high-density (n(H I)  7 × 103 atoms cm−3 ) halo containing a large fraction of the nebular mass (Mhalo ≥ 0.20 M ). The kinematics, physical conditions and ionic structu ...
- Mineralogical Society of America
- Mineralogical Society of America

1 2 3 4 5 ... 237 >

Standard solar model

The standard solar model (SSM) is a mathematical treatment of the Sun as a spherical ball of gas (in varying states of ionisation, with the hydrogen in the deep interior being a completely ionised plasma). This model, technically the spherically symmetric quasi-static model of a star, has stellar structure described by several differential equations derived from basic physical principles. The model is constrained by boundary conditions, namely the luminosity, radius, age and composition of the Sun, which are well determined. The age of the Sun cannot be measured directly; one way to estimate it is from the age of the oldest meteorites, and models of the evolution of the Solar System. The composition in the photosphere of the modern-day Sun, by mass, is 74.9% hydrogen and 23.8% helium. All heavier elements, called metals in astronomy, account for less than 2 percent of the mass. The SSM is used to test the validity of stellar evolution theory. In fact, the only way to determine the two free parameters of the stellar evolution model, the helium abundance and the mixing length parameter (used to model convection in the Sun), are to adjust the SSM to ""fit"" the observed Sun.
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