Browsing by Subject "abundance"
Now showing 1 - 20 of 20
- Results Per Page
- Sort Options
Item 18 Sco: A Solar Twin Rich In Refractory And Neutron-Capture Elements. Implications For Chemical Tagging(2014-08) Melendez, Jorge; Ramirez, Ivan; Karakas, Amanda I.; Yong, David; Monroe, TalaWanda R.; Bedell, Megan; Bergemann, Maria; Asplund, Martin; Maia, Marcelo Tucci; Bean, Jacob; do Nascimento, Jose-Dias; Bazot, Michael; Alves-Brito, Alan; Freitas, Fabricio C.; Castro, Matthieu; Ramirez, IvanWe study with unprecedented detail the chemical composition and stellar parameters of the solar twin 18 Sco in a strictly differential sense relative to the Sun. Our study is mainly based on high-resolution (R similar to 110,000), high signal-to-noise ratio (800-1,000) Very Large Telescope UVES spectra, which allow us to achieve a precision of about 0.005 dex in differential abundances. The effective temperature and surface gravity of 18 Sco are T-eff = 5823 +/- 6 K and log g = 4.45 +/- 0.02 dex, i.e., 18 Sco is 46 +/- 6 K hotter than the Sun and log g is 0.01 +/- 0.02 dex higher. Its metallicity is [Fe/H] = 0.054 +/- 0.005 dex, and its microturbulence velocity is +0.02 +/- 0.01 km s-1 higher than solar. Our precise stellar parameters and differential isochrone analysis show that 18 Sco has a mass of 1.04 +/- 0.02 M-circle dot and that it is similar to 1.6 Gyr younger than the Sun. We use precise High Accuracy Radial velocity Planet Searcher (HARPS) radial velocities to search for planets, but none are detected. The chemical abundance pattern of 18 Sco displays a clear trend with condensation temperature, thus showing higher abundances of refractories in 18 Sco than in the Sun. Intriguingly, there are enhancements in the neutron-capture elements relative to the Sun. Despite the small element-to-element abundance differences among nearby n-capture elements (similar to 0.02 dex), we successfully reproduce the r-process pattern in the Solar System. This is independent evidence for the universality of the r process. Our results have important implications for chemical tagging in our Galaxy and nucleosynthesis in general.Item The ACS Survey Of Galactic Globular Clusters. III. The Double Subgiant Branch Of NGC 1851(2008-01) Milone, A. P.; Bedin, L. R.; Piotto, G.; Anderson, J.; King, I. R.; Sarajedini, A.; Dotter, A.; Chaboyer, B.; Marin-Franch, A.; Majewski, S.; Aparicio, A.; Hempel, M.; Paust, N. E. Q.; Reid, I. N.; Rosenberg, A.; Siegel, M.; Siegel, M.Photometry with the Hubble Space Telescope Advanced Camera for Surveys (HSTACS) reveals that the subgiant branch (SGB) of the globular cluster NGC 1851 splits into two well-defined branches. If the split is due only to an age effect, the two SGBs would imply two star formation episodes separated by similar to 1 Gyr. We discuss other anomalies in NGC 1851 that could be interpreted in terms of a double stellar population. Finally, we compare the case of NGC 1851 with the other two globulars known to host multiple stellar populations, and show that all three clusters differ in several important respects.Item The APEX Quantitative Proteomics Tool: Generating Protein Quantitation Estimates from LC-MS/MS Proteomics Results(2008-12) Braisted, John C.; Kuntumalla, Srilatha; Vogel, Christine; Marcotte, Edward M.; Rodrigues, Alan R.; Wang, Rong; Huang, Shih0Ting; Ferlanti, Erik S.; Saeed, Alexander I.; Fleischmann, Robert D.; Peterson, Scott N.; Pieper, Rembert; Vogel, Christine; Marcotte, Edward M.Mass spectrometry (MS) based label-free protein quantitation has mainly focused on analysis of ion peak heights and peptide spectral counts. Most analyses of tandem mass spectrometry (MS/MS) data begin with an enzymatic digestion of a complex protein mixture to generate smaller peptides that can be separated and identified by an MS/MS instrument. Peptide spectral counting techniques attempt to quantify protein abundance by counting the number of detected tryptic peptides and their corresponding MS spectra. However, spectral counting is confounded by the fact that peptide physicochemical properties severely affect MS detection resulting in each peptide having a different detection probability. Lu et al. (2007) described a modified spectral counting technique, Absolute Protein Expression (APEX), which improves on basic spectral counting methods by including a correction factor for each protein (called O(i) value) that accounts for variable peptide detection by MS techniques. The technique uses machine learning classification to derive peptide detection probabilities that are used to predict the number of tryptic peptides expected to be detected for one molecule of a particular protein (O(i)). This predicted spectral count is compared to the protein's observed MS total spectral count during APEX computation of protein abundances. Results: The APEX Quantitative Proteomics Tool, introduced here, is a free open source Java application that supports the APEX protein quantitation technique. The APEX tool uses data from standard tandem mass spectrometry proteomics experiments and provides computational support for APEX protein abundance quantitation through a set of graphical user interfaces that partition thparameter controls for the various processing tasks. The tool also provides a Z-score analysis for identification of significant differential protein expression, a utility to assess APEX classifier performance via cross validation, and a utility to merge multiple APEX results into a standardized format in preparation for further statistical analysis. Conclusion: The APEX Quantitative Proteomics Tool provides a simple means to quickly derive hundreds to thousands of protein abundance values from standard liquid chromatography-tandem mass spectrometry proteomics datasets. The APEX tool provides a straightforward intuitive interface design overlaying a highly customizable computational workflow to produce protein abundance values from LC-MS/MS datasets.Item The CN Isotopic Ratios In Comets(2009-08) Manfroid, J.; Jehin, E.; Hutsemekers, D.; Cochran, A.; Zucconi, J. M.; Arpigny, C.; Schulz, R.; Stuwe, J. A.; Ilyin, I.; Cochran, A.Our aim is to determine the isotopic ratios (12)C/(13)C and (14)N/(15)N in a variety of comets and link these measurements to the formation and evolution of the solar system. The (12)C/(13)C and (14)N/(15)N isotopic ratios are measured for the CN radical by means of high-resolution optical spectra of the R branch of the B-X (0, 0) violet band. 23 comets from different dynamical classes have been observed, sometimes at various heliocentric and nucleocentric distances, in order to estimate possible variations of the isotopic ratios in parent molecules. The (12)C/(13)C and (14)N/(15)N isotopic ratios in CN are remarkably constant (average values of, respectively, 91.0 +/- 3.6 and 147.8 +/- 5.7) within our measurement errors, for all comets whatever their origin or heliocentric distance. While the carbon isotopic ratio does agree with the terrestrial value (89), the nitrogen ratio is a factor of two lower than the terrestrial value (272), indicating a fractionation in the early solar system, or in the protosolar nebula, common to all the comets of our sample. This points towards a common origin of the comets independently of their birthplaces, and a relationship between HCN and CN.Item Distances To Galactic High-Velocity Clouds: Complex C(2007-12) Wakker, B. P.; York, D. G.; Howk, J. C.; Barentine, John C.; Wilhelm, R.; Peletier, R. F.; van Woerden, H.; Beers, Timothy C.; Ivezic, Z.; Richter, P.; Schwarz, U. J.; Barentine, John C.We report the first determination of a distance bracket for the high- velocity cloud (HVC) complex C. Combined with previous measurements showing that this cloud has a metallicity of 0.15 times solar, these results provide ample evidence that complex C traces the continuing accretion of intergalactic gas falling onto the Milky Way. Accounting for both neutral and ionized hydrogen as well as He, the distance bracket implies a mass of (3-14) x 10(6) M-circle dot, and the complex represents a mass inflow of 0.1-0.25 M-circle dot yr(-1). We base our distance bracket on the detection of Ca II absorption in the spectrum of the blue horizontal branch (BHB) star SDSS J120404.78 + 623345.6, in combination with a significant nondetection toward the BHB star BS 16034-0114. These results set a strong distance bracket of 3.7-11.2 kpc on the distance to complex C. A more weakly supported lower limit of 6.7 kpc may be derived from the spectrum of the BHB star BS 16079-0017.Item The Dual Origin Of The Nitrogen Deficiency In Comets: Selective Volatile Trapping In The Nebula And Postaccretion Radiogenic Heating(2012-10) Mousis, Olivier; Guilbert-Lepoutre, Aurelie; Lunine, Jonathan I.; Cochran, Anita L.; Waite, J. Hunter; Petit, Jean-Marc; Rousselot, Philippe; Cochran, Anita L.We propose a scenario that explains the apparent nitrogen deficiency in comets in away that is consistent with the fact that the surfaces of Pluto and Triton are dominated by nitrogen-rich ice. We use a statistical thermodynamic model to investigate the composition of the successive multiple guest clathrates that may have formed during the cooling of the primordial nebula from the most abundant volatiles present in the gas phase. These clathrates agglomerated with the other ices (pure condensates or stoichiometric hydrates) and formed the building blocks of comets. We report that molecular nitrogen is a poor clathrate former, when we consider a plausible gas-phase composition of the primordial nebula. This implies that its trapping into cometesimals requires a low disk temperature (similar to 20 K) in order to allow the formation of its pure condensate. We find that it is possible to explain the lack of molecular nitrogen in comets as a consequence of their postformation internal heating engendered by the decay of short-lived radiogenic nuclides. This scenario is found to be consistent with the presence of nitrogen-rich ice covers on Pluto and Triton. Our model predicts that comets should present xenon-to-water and krypton-to-water ratios close to solar xenon-to-oxygen and krypton-to-oxygen ratios, respectively. In contrast, the argon-to-water ratio is predicted to be depleted by a factor of similar to 300 in comets compared to solar argon-to-oxygen, as a consequence of poor trapping efficiency and radiogenic heating.Item Dynamics And Distribution Of Cyanophages And Their Effect On Marine Synechococcus Spp(1994-09) Suttle, Curtis A.; Chan, Amy M.; Suttle, Curtis A.; Chan, Amy M.Cyanophages infecting marine Synechococcus cells were frequently very abundant and were found in every seawater sample along a transect in the western Gulf of Mexico and during a 28-month period in Aransas Pass, Tex. In Aransas Pass their abundance varied seasonally, with the lowest concentrations coincident with cooler water and lower salinity. Along the transect, viruses infecting Synechococcus strains DC2 and SYN48 ranged in concentration from a few hundred per milliliter at 97 m deep and 83 km offshore to ca. 4 x 10(5) ml(-1) near the surface at stations within 18 km of the coast. The highest concentrations occurred at the surface, where salinity decreased from ca. 35.5 to 34 ppt and Synechococcus concentrations were greatest. Viruses infecting strains SNC1, SNC2, and 838BG were distributed in a similar manner but were much less abundant (<10 to >5 x 10(3) ml(-1)). When Synechococcus concentrations exceeded ca. 10(3) ml(-1), cyanophage concentrations increased markedly (ca. 10(2) to > 10(5) ml(-1)), suggesting that a minimum host density was required for efficient viral propagation. Data on the decay rate of viral infectivity d (per day), as a function of solar irradiance I (millimoles of quanta per square meter per second), were used to develop a relationship (d = 0.2610I-0.00718; r(2) = 0.69) for conservatively estimating the destruction of infectious viruses in the mixed layer of two offshore stations. Assuming that virus production balances losses and that the burst size is 250, ca. 5 to 7% of Synechococcus cells would be infected daily by viruses. Calculations based on contact rates between Synechococcus cells and infectious viruses produce similar results (5 to 14%). Moreover, balancing estimates of viral production with contact rates for the farthest offshore station required that most Synechococcus cells be susceptible to infection, that most contacts result in infection, and that the burst size be about 324 viruses per lytic event. In contrast, in nearshore waters, where ca. 80% of Synechococcus cells would be contacted daily by infectious cyanophages, only ca. 1% of the contacts would have to result in infection to balance the estimated virus removal rates. These results indicate that cyanophages are an abundant and dynamic component of marine planktonic communities and are probably responsible for lysing a small but significant portion of the Synechococcus population on a daily basis.Item Granulation Signatures in the Spectrum of the Very Metal-Poor Red Giant HD 122563(2010-12) Ramirez, I.; Collet, R.; Lambert, David L.; Prieto, Carlos Allende; Asplund, M.; Lambert, D. L.A very high resolution (R = lambda/Delta lambda = 200,000), high signal-to-noise ratio (S/N similar or equal to 340) blue-green spectrum of the very metal-poor ([Fe/H] similar or equal to -2.6) red giant star HD 122563 has been obtained by us at McDonald Observatory. We measure the asymmetries and core wavelengths of a set of unblended Fe I lines covering a wide range of line strength. Line bisectors exhibit the characteristic C-shape signature of surface convection (granulation) and they span from about 100 m s(-1) in the strongest Fe I features to 800 m s(-1) in the weakest ones. Core wavelength shifts range from about -100 to -900 m s(-1), depending on line strength. In general, larger blueshifts are observed in weaker lines, but there is increasing scatter with increasing residual flux. Assuming local thermodynamic equilibrium (LTE), we synthesize the same set of spectral lines using a state-of-the-art three-dimensional (3D) hydrodynamic simulation for a stellar atmosphere of fundamental parameters similar to those of HD 122563. We find good agreement between model predictions and observations. This allows us to infer an absolute zero point for the line shifts and radial velocity. Moreover, it indicates that the structure and dynamics of the simulation are realistic, thus providing support to previous claims of large 3D-LTE corrections to elemental abundances and fundamental parameters of very metal-poor red giant stars obtained with standard 1D-LTE spectroscopic analyses, as suggested by the hydrodynamic model used here.Item Improved yttrium and zirconium abundances in metal-poor stars(2012-01) Violante, RenataWe present new abundances of the lighter n-capture elements, Yttrium (Z=30) and Zirconium (Z=40) in the very metal-poor, r-process rich stars BD+17 3248 and HD 221170. Very accurate abundances were obtained by use of the new transition probabilities for Y II published by Biemont et al. 2011, and Zr II by Malcheva et al. 2006, and by expanding the number of transitions employed for each element. For example, in BD+17 3248, we find log(Epsilon)=-0.03 +/-0.03 (Sigma=0.15 from 23 lines) for Y II. As for Zr II, log(Epsilon)=0.65 +/- 0.03 (Sigma=0.1 from 13 lines). The resulting abundance ratio is [Y/Zr]=-0.68 +/- 0.05. The results for HD 221170 are in accord with those of BD+17 3248. The quantity of lines used to form the abundance means has increased significantly since the original studies of these stars, resulting in more trustworthy abundances. These observed abundance ratios are in agreement with the r-process only value predicted from stellar models, but is under-abundant compared to an empirical model derived from direct analyses of meteoritic material. This ambiguity should stimulate further nucleosynthetic analysis to explain this abundance ratio.Item A Laboratory Log(Gf) Measurement of the TIII 15873.84 Angstrom H-Band Line in Support of SDSS-III APOGEE(2014-06) Wood, M. P.; Lawler, James E.; Shetrone, Matthew D.; Shetrone, Matthew D.The SDSS-III APOGEE collaboration has identified a single useable line in the H-band spectra of APOGEE target stars arising from a singly ionized species. This line of TiII (lambda(air) 15873.84 angstrom) is therefore of great importance for use in stellar surface gravity, or log(g), determinations via the Saha equation. While a theoretical estimate of the line strength exists, to date no laboratory measurement of the line strength has been reported. Herein we report an absolute laboratory transition probability measurement for this important TiII line. A relative line strength measurement is made of the TiII H-band line of interest and a reference line with a previously reported absolute transition probability. This ratio is measured using multiple spectra of a high-current water-cooled HC lamp recorded with a calibrated FT-IR spectrometer.Item Letter to H.B. Stenzel from John S. Cruse, Jr. on 1949-12-06(1949-12-06) Cruse, John S. , Jr.Item Letter to J.Kenneth Blackmar from H.B. Stenzel on 1943-09-20(1943-09-20) Stenzel, Henryk B.Item New Rare Earth Element Abundance Distributions for the Sun and Five R-Process-Rich Very Metal-Poor Stars(2009-05) Sneden, Christopher; Lawler, James E.; Cowan, John J.; Ivans,, Inese I.; Den Hartog, Elizabeth A.; Sneden, ChristopherWe have derived new abundances of the rare earth elements Pr, Dy, Tm, Yb, and Lu for the solar photosphere and for five very metal-poor, neutron-capture r-process-rich giant stars. The photospheric values for all five elements are in good agreement with meteoritic abundances. For the low-metallicity sample, these abundances have been combined with new Ce abundances from a companion paper, and reconsideration of a few other elements in individual stars, to produce internally consistent Ba, rare earth, and Hf ( 56 <= Z <= 72) element distributions. These have been used in a critical comparison between stellar and solar r-process abundance mixes.Item New Results From Bright Metal-Poor Stars In The Hamburg/Eso Survey(2008-03) Frebel, A.; Beers, T. C.; Marsteller, B.; Frebel, AnnaWe present an abundance analysis of BE 1327-2326, currently the most iron-poor star known, based on a newly acquired VLT spectrum. The ID abundance pattern is corrected for 3D effects. The 3D iron abundance is [Fe/H] = -5.9, while the CNO elements of the star are extremely overabundant [CNO[Fe] similar to 3 to 4). The cosmologically important element Li is still not detected; the new upper limit is A (Li) < 0.6. A new analysis of the medium-resolution data of the sample of bright metal-poor stars from the Hamburg/ESO Survey (HES) was carried out. We are using this sample to obtain clues to the chemical nature of the early Universe by investigating the kinematic properties of the sample. Based on estimated [Fe/H] and [C/Fe], we are also able to use the sample to test a formation mechanism for low-mass metal-poor stars.Item Quantitative Spectroscopy In 3D(2009-09) Koesterke, L.; Koesterke, L.The Advanced Spectrum Synthesis 3D Tool ASSET is introduced. ASSET allows for the accurate and fast calculation of spectra from 3D hydrodynamical models. To achieve the highest numerical accuracy 3(rd)-order Bezier interpolations are employed and all available information from the model grid with respect to the spacial and frequency resolution is exploited. ASSET is fully parallelized with OpenMP and MPI and highly optimized to run at about 25% of peak speed on workstations and clusters. The emergent flux for a single spectral line can be calculated from dozens of snapshots within a few minutes, and the whole spectrum (2 . 10(6) frequencies) can be calculated on a small cluster (a few hundred threads) within a day. The numerical methods, the serial optimization and the parallel implementation are described in some detail.Item Searching For Chemical Signatures Of Multiple Stellar Populations In The Old, Massive Open Cluster NGC 6791(2014-11) Bragaglia, Angela; Sneden, Christopher; Carretta, Eugenio; Gratton, Raffaele G.; Lucatello, Sara; Bernath, Peter F.; Brooke, James S. A.; Ram, Ram S.; Sneden, ChristopherGalactic open and globular clusters (OCs, GCs) appear to inhabit separate regions of the age-mass plane. However, the transition between them is not easily defined because there is some overlap between high-mass, old OCs and low-mass, young GCs. We are exploring the possibility of a clear-cut separation between OCs and GCs using an abundance feature that has been found so far only in GCs: (anti) correlations between light elements. Among the coupled abundance trends, the Na-O anticorrelation is the most widely studied. These anticorrelations are the signature of self-enrichment, i.e., of a formation mechanism that implies multiple generations of stars. Here we concentrate on the old, massive, metal-rich OC NGC 6791. We analyzed archival Keck/HIRES spectra of 15 NGC 6791 main-sequence turnoff and evolved stars, concentrating on the derivation of C, N, O, and Na abundances. We also used WIYN/Hydra spectra of 21 evolved stars (one is in common). Given the spectral complexity of the very metal-rich NGC 6791 stars, we employed spectrum synthesis to measure most of the abundances. We confirmed the cluster super-solar metallicity and abundances of Ca and Ni that have been derived in past studies. More importantly, we did not detect any significant star-to-star abundance dispersion in C, N, O, and Na. Based on the absence of a clear Na-O anticorrelation, NGC 6791 can still be considered a true OC, hosting a single generation of stars and not a low-mass GC.Item Searching For Multiple Stellar Populations In The Massive, Old Open Cluster Berkeley 39(2012-12) Bragaglia, A.; Gratton, R. G.; Carretta, E.; D'Orazi, V.; Sneden, Christopher; Lucatello, S.; Sneden, ChristopherThe most massive star clusters include several generations of stars with a different chemical composition (mainly revealed by an Na-O anti-correlation) while low-mass star clusters appear to be chemically homogeneous. We are investigating the chemical composition of several clusters with masses of a few 10(4) M-circle dot to establish the lower mass limit for the multiple stellar population phenomenon. Using VLT/FLAMES spectra we determine abundances of Fe, O, Na, and several other elements (a, Fe-peak, and neutron-capture elements) in the old open cluster Berkeley 39. This is a massive open cluster: M similar to 10(4) M-circle dot, approximately at the border between small globular clusters and large open clusters. Our sample size of about 30 stars is one of the largest studied for abundances in any open cluster to date, and will be useful to determine improved cluster parameters, such as age, distance, and reddening when coupled with precise, well-calibrated photometry. We find that Berkeley 39 is slightly metal-poor, <[Fe/H]> = -0.20, in agreement with previous studies of this cluster. More importantly, we do not detect any star-to-star variation in the abundances of Fe, O, and Na within quite stringent upper limits. The rms scatter is 0.04, 0.10, and 0.05 dex for Fe, O, and Na, respectively. This small spread can be entirely explained by the noise in the spectra and by uncertainties in the atmospheric parameters. We conclude that Berkeley 39 is a single-population cluster.Item Temporal Variation In The Carrying Capacity Of A Perennial Grass Population(2010-05) Fowler, N. L.; Pease, C. M.; Fowler, N. L.Density dependence and, therefore, K (carrying capacity, equilibrium population size) are central to understanding and predicting changes in population size (N). Although resource levels certainly fluctuate, K has almost always been treated as constant in both theoretical and empirical studies. We quantified temporal variation in K by fitting extensions of standard population dynamic models to 16 annual censuses of a population of the perennial bunch-grass Bouteloua rigidiseta. Variable-K models provided substantially better fits to the data than did models that varied the potential rate of population increase. The distribution of estimated values of K was skewed, with a long right tail (i.e., a few >jackpot> years). The population did not track K closely. Relatively slow responses to changes in K combined with large, rapid changes in K sometimes caused N to be far from K. In 13%-20% of annual intervals, K was so much larger than N that the population's dynamics were best described by geometric growth and the population was, in effect, unregulated. Explicitly incorporating temporal variation in K substantially improved the realism of models with little increase in model complexity and provided novel information about this population's dynamics. Similar methods would be applicable to many other data sets.Item Transiting Exoplanets From The Corot Space Mission XIV. CoRoT-11B: A Transiting Massive >Hot-Jupiter> In A Prograde Orbit Around A Rapidly Rotating F-Type Star(2010-12) Gandolfi, D.; Hebrard, G.; Alonso, R.; Deleuil, M.; Guenther, E. W.; Fridlund, M.; Endl, M.; Eigmuller, P.; Csizmadia, S.; Havel, M.; Aigrain, S.; Auvergne, M.; Baglin, A.; Barge, P.; Bonomo, A. S.; Borde, P.; Bouchy, F.; Bruntt, H.; Cabrera, J.; Carpano, S.; Carone, L.; Cochran, W. D.; Deeg, H. J.; Dvorak, R.; Eisloffel, J.; Erikson, A.; Ferraz-Mello, S.; Gazzano, J. C.; Gibson, N. B.; Gillon, M.; Gondoin, P.; Guillot, T.; Hartmann, M.; Hatzes, A.; Jorda, L.; Kabath, P.; Leger, A.; Llebaria, A.; Lammer, H.; MacQueen, P. J.; Mayor, M.; Mazeh, T.; Moutou, C.; Ollivier, M.; Patzold, M.; Pepe, F.; Queloz, D.; Rauer, H.; Rouan, D.; Samuel, B.; Schneider, J.; Stecklum, B.; Tingley, B.; Udry, S.; Wuchterl, G.; Cochran, W. D.; Endl, M.; MacQueen, P.J.The CoRoT exoplanet science team announces the discovery of CoRoT-11b, a fairly massive hot-Jupiter transiting a V = 12.9 mag F6 dwarf star (M(*) = 1.27 +/- 0.05 M(circle dot), R(*) = 1.37 +/- 0.03 R(circle dot), T(eff) = 6440 +/- 120 K), with an orbital period of P = 2.994329 +/- 0.000011 days and semi-major axis a = 0.0436 +/- 0.005 AU. The detection of part of the radial velocity anomaly caused by the Rossiter-McLaughlin effect shows that the transit-like events detected by CoRoT are caused by a planet-sized transiting object in a prograde orbit. The relatively high projected rotational velocity of the star (upsilon sin i(star) = 40 +/- 5 km s(-1)) places CoRoT-11 among the most rapidly rotating planet host stars discovered so far. With a planetary mass of M(p) = 2.33 +/- 0.34 M(Jup) and radius R(p) = 1.43 +/- 0.03 R(Jup), the resulting mean density of CoRoT-11b (rho(p) = 0.99 +/- 0.15 g/cm(3)) can be explained with a model for an inflated hydrogen-planet with a solar composition and a high level of energy dissipation in its interior.Item X-Shooter Observations of Main-Sequence Stars in the Globular Cluster NGC 2808: First Chemical Tagging of A He-Normal and A He-Rich Dwarf(2010-09) Bragaglia, A.; Carretta, E.; Gratton, R. G.; Lucatello, Sara; Milone, A.; Piotto, G.; D'Orazi, V.; Cassisi, S.; Sneden, Christopher; Bedin, L. R.; Sneden, ChristopherWe present the first chemical composition study of two unevolved stars in the globular cluster NGC 2808, obtained with the X-shooter spectrograph at VLT.NGC 2808 shows three discrete, well-separated main sequences. The most accepted explanation for this phenomenon is that their stars have different helium contents. We observed one star on the bluest main sequence (bMS, claimed to have a high helium content, Y similar to 0.4) and the other on the reddest main sequence (rMS, consistent with a canonical helium content, Y = 0.245). We analyzed features of NH, CH, Na, Mg, Al, and Fe. While Fe, Ca, and other elements have the same abundances in the two stars, the bMS star shows a huge enhancement of N, a depletion of C, an enhancement of Na and Al, and a small depletion of Mg with respect to the rMS star. This is exactly what is expected if stars on the bMS formed from the ejecta produced by an earlier stellar generation in the complete CNO and MgAl cycles whose main product is helium. The elemental abundance pattern differences in these two stars are consistent with the differences in the helium content suggested by the color-magnitude diagram positions of the stars.