Search results for "Astronomical models"
showing 4 items of 4 documents
Is there any scaling in the cluster distribution?
1994
We apply fractal analysis methods to investigate the scaling properties in the Abell and ACO catalogs of rich galaxy clusters. We also discuss different technical aspects of the method when applied to data sets with small number of points as the cluster catalogs. Results are compared with simulations based on the Zel'dovich approximation. We limit our analysis to scales less than 100 $\hm$. The cluster distribution show a scale invariant multifractal behavior in a limited scale range. For the Abell catalog this range is 15--60$\hm$, while for the ACO sample it extends to smaller scales. Despite this difference in the extension of the scale--range where scale--invariant clustering takes plac…
Stellar parameters & abund. from BACCHUS analysis
2019
Data from the SDSS-IV/Apache Point Observatory Galactic Evolution Experiment (APOGEE-2) have been released as part of SDSS Data Releases 13 (DR13) and 14 (DR14). These include high-resolution H-band spectra, radial velocities, and derived stellar parameters and abundances. DR13, released in 2016 August, contained APOGEE data for roughly 150000 stars, and DR14, released in 2017 August, added about 110000 more. Stellar parameters and abundances have been derived with an automated pipeline, the APOGEE Stellar Parameter and Chemical Abundance Pipeline (ASPCAP). We evaluate the performance of this pipeline by comparing the derived stellar parameters and abundances to those inferred from optical …
Neutrinos from GRBs with ANTARES
2013
A search for muon neutrinos in coincidence with gamma-ray bursts with the ANTARES neutrino detector using data from the end of 2007 to 2011 is performed. Expected neutrino fluxes are calculated for each burst individually. The most recent numerical calculations of the spectra using the NeuCosmA code are employed, which include Monte Carlo simulations of the full underlying photohadronic interaction processes. The discovery probability for a selection of 296 gamma-ray bursts in the given period is optimised using an extended maximum-likelihood strategy. No significant excess over background is found in the data, and 90% confidence level upper limits are placed on the total expected flux acco…
Solar models with accretion. I.
2013
We generate new standard solar models using newly analyzed nuclear fusion cross sections and present results for helioseismic quantities and solar neutrino fluxes. The status of the solar abundance problem is discussed. We investigate whether nonstandard solar models with accretion from the protoplanetary disk might alleviate this problem. We examine a broad range of models, analyzing metal-enriched and metal-depleted accretion and three scenarios for the timing of accretion. Only partial solutions are found. For metal-rich accreted material (Z_ac_>~0.018) there exist combinations of accreted mass and metallicity that bring the depth of the convective zone into agreement with the helioseism…