W. M. White Geochemistry Chapter 10: Cosmochemistry
... we learn about the evolution of the Earth by examining old rocks, we can learn about the evolution of the cosmos by looking at old stars. The old stars of Population II are considerably poorer in heavy elements than are young stars. In particular, Population II stars have a Fe/H ratio typically a fa ...
... we learn about the evolution of the Earth by examining old rocks, we can learn about the evolution of the cosmos by looking at old stars. The old stars of Population II are considerably poorer in heavy elements than are young stars. In particular, Population II stars have a Fe/H ratio typically a fa ...
WELCOME TO THE MILKY WAY
... Let’s start with our Sun. Not so long ago, the Sun was believed to be the center of the universe, but it is not. The Sun lies at 30,000 ly from the center of the Milky Way. Our day star is a modest star, one member of our home galaxy. Today astronomers catalog our Sun as a small G2V star with an abs ...
... Let’s start with our Sun. Not so long ago, the Sun was believed to be the center of the universe, but it is not. The Sun lies at 30,000 ly from the center of the Milky Way. Our day star is a modest star, one member of our home galaxy. Today astronomers catalog our Sun as a small G2V star with an abs ...
Protoplanetary Discs
... 1. The invention of infrared detectors ⇒ Infrared measurements revealed circumstellar matter in “spectral enegery distributions” (SEDs) ⇒ Differences between “extinction” and “excess” allowed the conclusion that matter is distributed not in a shell, but in a disc ...
... 1. The invention of infrared detectors ⇒ Infrared measurements revealed circumstellar matter in “spectral enegery distributions” (SEDs) ⇒ Differences between “extinction” and “excess” allowed the conclusion that matter is distributed not in a shell, but in a disc ...
Chemical composition of 90 F and G disk dwarfs
... evolution (GCE) in detail, some old conclusions have, however, been challenged and new questions have arisen. Particularly important is the detailed abundance analysis of 189 F and G dwarfs with −1.1 < [Fe/H] < 0.25 by Edvardsson et al. (1993a, hereafter EAGLNT). The main results from this work may ...
... evolution (GCE) in detail, some old conclusions have, however, been challenged and new questions have arisen. Particularly important is the detailed abundance analysis of 189 F and G dwarfs with −1.1 < [Fe/H] < 0.25 by Edvardsson et al. (1993a, hereafter EAGLNT). The main results from this work may ...
Debris disks and the search for life in the universe Gianni Cataldi
... be the building blocks of planets. By definition, planetesimals are bodies massive enough that their orbital evolution is determined by mutual gravitational interactions, in contrast to smaller dust particles for which aerodynamic interactions with the gas are more important (Armitage 2009). Thus, p ...
... be the building blocks of planets. By definition, planetesimals are bodies massive enough that their orbital evolution is determined by mutual gravitational interactions, in contrast to smaller dust particles for which aerodynamic interactions with the gas are more important (Armitage 2009). Thus, p ...
Oxygen and Neon Abundances of B-Type Stars in Comparison with
... UVBYBETA (estimation of intrinsic colors corrected for interstellar reddening) and TEFFLOGG (Teff =logg determination from dereddened colors) programs. The observational data of b y, c1 , m1 , and ˇ were taken from Hauck and Mermilliod (1998) via the SIMBAD database. The resulting Teff and logg are ...
... UVBYBETA (estimation of intrinsic colors corrected for interstellar reddening) and TEFFLOGG (Teff =logg determination from dereddened colors) programs. The observational data of b y, c1 , m1 , and ˇ were taken from Hauck and Mermilliod (1998) via the SIMBAD database. The resulting Teff and logg are ...
Chandra
... By combining ROBAT x-ray observations with EUVE EUV observations of the B bright giant E Canis Majoris, Cohen et al. (1996) were able to place constraints on wind attenuation and temperature distribution. This was the first analysis of high-energy hot-star spectra with high enough resolution to reso ...
... By combining ROBAT x-ray observations with EUVE EUV observations of the B bright giant E Canis Majoris, Cohen et al. (1996) were able to place constraints on wind attenuation and temperature distribution. This was the first analysis of high-energy hot-star spectra with high enough resolution to reso ...
Molecules in Space
... the next section, even the so-called dense molecular clouds correspond to what, on Earth, would be considered an ultrahigh vacuum. Typically, they contain a few tens of thousand particles per cubic centimetre and are cold with temperatures in the range 10 to 100 K. Under these conditions, the chance ...
... the next section, even the so-called dense molecular clouds correspond to what, on Earth, would be considered an ultrahigh vacuum. Typically, they contain a few tens of thousand particles per cubic centimetre and are cold with temperatures in the range 10 to 100 K. Under these conditions, the chance ...
Accuracy of spectroscopy-based radioactive dating of stars
... et al. 1991, and references therein for an account of its early applications). Since then it has been applied in a number of cases (among the most recent Frebel et al. 2007) but, typically, as a “side product” of analyses of the more general n-capture enrichment patterns. To our knowledge, the only ...
... et al. 1991, and references therein for an account of its early applications). Since then it has been applied in a number of cases (among the most recent Frebel et al. 2007) but, typically, as a “side product” of analyses of the more general n-capture enrichment patterns. To our knowledge, the only ...
Carbon-enhanced metal-poor stars in dwarf galaxies
... in the Galactic halo. Moreover, we can see that the frequency of CEMP-no stars among these “hyper-iron-poor stars” is extremely high: 8 out of 9 stars at [Fe/H]≤ −4.5 are CEMP-no stars. These objects have peculiar chemical abundance patterns consistent with the yields predicted for primordial faint ...
... in the Galactic halo. Moreover, we can see that the frequency of CEMP-no stars among these “hyper-iron-poor stars” is extremely high: 8 out of 9 stars at [Fe/H]≤ −4.5 are CEMP-no stars. These objects have peculiar chemical abundance patterns consistent with the yields predicted for primordial faint ...
Ptolemy: on trial for fraud
... above all, that the Almagest is not like a modern research paper. It is a well-honed textbook, modelled as much as applicable on Euclid’s Elements. It was no doubt Ptolemy’s intention to present the procedures with sample data so that future astronomers could see how it was done and could introduce ...
... above all, that the Almagest is not like a modern research paper. It is a well-honed textbook, modelled as much as applicable on Euclid’s Elements. It was no doubt Ptolemy’s intention to present the procedures with sample data so that future astronomers could see how it was done and could introduce ...
APS Apr 2008 - User Web Pages
... lightcurves (this is not a fit!) Except for a “bump” during the burst rise, which may be an artifact of the finite time for the burning to spread, or something arising from a particular nuclear reaction ...
... lightcurves (this is not a fit!) Except for a “bump” during the burst rise, which may be an artifact of the finite time for the burning to spread, or something arising from a particular nuclear reaction ...
Neutrinos and Nucleosynthesis
... A core-collapse supernova happens, when a massive star has burned all its fuel, leading to an onion like structure of the star. Due to the deficiency in burning material the star is not able to counterbalance the gravitational pressure pushing inwards. This leads to a compression of the core of the ...
... A core-collapse supernova happens, when a massive star has burned all its fuel, leading to an onion like structure of the star. Due to the deficiency in burning material the star is not able to counterbalance the gravitational pressure pushing inwards. This leads to a compression of the core of the ...
opportunities nuclear astrophysics
... Advances in computational capability has occurred just in time to allow us to take advantage of the new observations and nuclear physics results. For example, it may soon be possible to begin study of a supernova explosion in two and then three dimensions with accurate atomic and nuclear physics inp ...
... Advances in computational capability has occurred just in time to allow us to take advantage of the new observations and nuclear physics results. For example, it may soon be possible to begin study of a supernova explosion in two and then three dimensions with accurate atomic and nuclear physics inp ...
don_lamb - New Views of the Universe
... accretion disk) Explains long GRBs Dominant timescale is set by jet propagation through collapsing core (~10-20 s) ...
... accretion disk) Explains long GRBs Dominant timescale is set by jet propagation through collapsing core (~10-20 s) ...
Three newly discovered sub-Jupiter-mass planets: WASP
... We determined the projected stellar rotation velocity (vsin I) by fitting the profiles of several unblended Fe I lines. We took macroturbulence values of 2.3 ± 0.3 km s−1 for WASP-70A and 1.2 ± 0.3 km s−1 for WASP-84 from the tabulation of Bruntt et al. (2010a). For WASP-69 and WASP-70B, we assumed ...
... We determined the projected stellar rotation velocity (vsin I) by fitting the profiles of several unblended Fe I lines. We took macroturbulence values of 2.3 ± 0.3 km s−1 for WASP-70A and 1.2 ± 0.3 km s−1 for WASP-84 from the tabulation of Bruntt et al. (2010a). For WASP-69 and WASP-70B, we assumed ...
103-122
... spectra of 29 disc dwarfs of F type in selected intervals from which abundances of a selection of light through heavy elements are derived using MARCS models and solar gf-values. The basic parameters—Teff and log g—are computed from Strömgren photometric indices. This analysis appears to be the most ...
... spectra of 29 disc dwarfs of F type in selected intervals from which abundances of a selection of light through heavy elements are derived using MARCS models and solar gf-values. The basic parameters—Teff and log g—are computed from Strömgren photometric indices. This analysis appears to be the most ...
Super-solar Metal Abundances in Two Galaxies at ζ ∼ 3.57
... both in G0 and G1. From the rest-frame UV emission in the GRB location, we derive a relatively high, not corrected for dust extinction, star-formation rate SFR ≈ 6 M# yr−1 . These properties suggest a possible connection between some high-redshift GRB host galaxies and high-z massive sub-millimeter ...
... both in G0 and G1. From the rest-frame UV emission in the GRB location, we derive a relatively high, not corrected for dust extinction, star-formation rate SFR ≈ 6 M# yr−1 . These properties suggest a possible connection between some high-redshift GRB host galaxies and high-z massive sub-millimeter ...
November, 2015 - The Baton Rouge Astronomical Society
... 847 and counting: that’s the number of planets confirmed as existing around 642 stars within several hundred light-years of our Sun. And more than 2,000 additional detections are awaiting confirmation by follow-up observations. By far, the most potential exoplanets have been found by the NASA spacec ...
... 847 and counting: that’s the number of planets confirmed as existing around 642 stars within several hundred light-years of our Sun. And more than 2,000 additional detections are awaiting confirmation by follow-up observations. By far, the most potential exoplanets have been found by the NASA spacec ...
WG4: Nuclear Astrophysics
... are able to explain the abundances of sprocess nuclei observed in the Sun, pre-solar grains and galaxies. Models of massive stars that include the physics of rotation with spherically symmetric prescriptions can explain the enhancement of 14N in the early Universe and, thus, the enhanced efficiency ...
... are able to explain the abundances of sprocess nuclei observed in the Sun, pre-solar grains and galaxies. Models of massive stars that include the physics of rotation with spherically symmetric prescriptions can explain the enhancement of 14N in the early Universe and, thus, the enhanced efficiency ...
Stellar populations in the nuclear regions of nearby radio galaxies
... We present optical spectra of the nuclei of seven luminous ðP178 MHz * 1025 W Hz21 Sr21 Þ nearby ðz , 0:08Þ radio galaxies, which mostly correspond to the FR II class. In two cases, Hydra A and 3C 285, the Balmer and l4000-Å break indices constrain the spectral types and luminosity classes of the s ...
... We present optical spectra of the nuclei of seven luminous ðP178 MHz * 1025 W Hz21 Sr21 Þ nearby ðz , 0:08Þ radio galaxies, which mostly correspond to the FR II class. In two cases, Hydra A and 3C 285, the Balmer and l4000-Å break indices constrain the spectral types and luminosity classes of the s ...
Unlocking the secrets of stellar haloes using combined star counts
... by counting the number of bright halo stars (red giant branch stars, asymptotic giant branch stars and upper main sequence stars) within a certain area. The bright stars only account for a fraction of the overall halo light, which means that the star counts must be calibrated on to a surface brightn ...
... by counting the number of bright halo stars (red giant branch stars, asymptotic giant branch stars and upper main sequence stars) within a certain area. The bright stars only account for a fraction of the overall halo light, which means that the star counts must be calibrated on to a surface brightn ...
R136a1
RMC 136a1 (usually abbreviated to R136a1) is a Wolf-Rayet star located at the center of R136, the central condensation of stars of the large NGC 2070 open cluster in the Tarantula Nebula. It lies at a distance of about 50 kiloparsecs (163,000 light-years) in the Large Magellanic Cloud. It has the highest mass and luminosity of any known star, at 265 M☉ and 8.7 million L☉, and also one of the hottest at over 50,000 K.