相关论文: On nonconvex constellations among primes II: (458,…
Extending our work on the $k$-tuple conjecture, we apply those methods to the Engelsma counterexamples (narrow constellations) of length $J=459$ and span $|s|=3242$. We track the evolution of these $58$ counterexamples from inadmissible…
We present a spectroscopic sample of 48 early-type galaxies in the rich cluster Abell 2218 and 50 galaxies in Abell 2390. Since both samples are very similar, we combine them and investigate a total number of 98 early-type galaxies at…
A few years ago we identified a recursion that works directly with the gaps among the generators in each stage of Eratosthenes sieve. This recursion provides explicit enumerations of sequences of gaps among the generators, which are known…
We investigate a spectroscopic sample of 48 early-type (E+S0) galaxies in the rich cluster Abell 2390 (z=0.23) and 48 E+S0 galaxies from a previously published survey of Abell 2218 (z=0.18). The A2390 spectra are based on Multi Object…
We introduce a method for showing that there exist prime numbers which are very close together. The method depends on the level of distribution of primes in arithmetic progressions. Assuming the Elliott-Halberstam conjecture, we prove that…
The study of cluster populations as tracer of galaxy evolution is now quite possible with 8 m class telescopes and modern instrumentation. The cluster population can be used as a good tracer of the star forming episodes undergone by the…
We discuss the galaxy population of the rich cluster MS1621.5+2640 at z=0.4274, based on spectra and imaging in a field of size 9 arcmin by 23 arcmin (~2 by 5 h**-1 Mpc). The sample comprises 277 galaxies, of which 112 are cluster members,…
Based on a large sample of 133 Galactic globular clusters we obtained a new estimate of the frequency of globular-cluster impacts onto the Galactic plane, which we found to be equal to three events per 1 Myr. Our computations involving new…
The Antlia galaxy cluster is the third nearest galaxy cluster after Virgo and Fornax. We used the wide-field MOSAIC camera of the 4-m CTIO telescope to search in the brightest cluster galaxies for globular cluster systems, which were…
We present new results on the Fundamental Plane of galaxies in two rich clusters, Cl1358+62 at $z=0.33$ and MS2053--04 at $z=0.58$, based on Keck and HST observations. Our new data triple the sample of galaxies with measured Fundamental…
We analyze a 19-night photometric search for transiting extrasolar planets in the open cluster NGC 1245. An automated transit search algorithm with quantitative selection criteria finds six transit candidates; none are bona fide planetary…
We present a detailed census of galaxies in and around PC217.96+32.3, a spectroscopically confirmed Coma analog at z=3.78. Diverse galaxy types identified in the field include Lya emitters (LAEs), massive star-forming galaxies, and…
Consider a system \Psi of non-constant affine-linear forms \psi_1,...,\psi_t: Z^d -> Z, no two of which are linearly dependent. Let N be a large integer, and let K be a convex subset of [-N,N]^d. A famous and difficult open conjecture of…
Protoclusters represent the most extreme environments in the very early Universe. They form from large-scale dark matter overdensities, harbouring an overabundance of galaxies fed by large gas reservoirs. Their early and accelerated…
In this paper we adopt a method to analyse absorption line spectra from elliptical galaxies that determines the dynamics of the galaxy and at the same time offers a way to study the stellar populations in that galaxy by a direct fit to the…
We present first results from the Survey for Transiting Extrasolar Planets in Stellar Systems (STEPSS). Our goal is to assess the frequency of close-in extrasolar planets around main-sequence stars in several open clusters. By concentrating…
Keck spectroscopy and Hubble Space Telescope WFPC2 imaging over a 1.5x1.5 Mpc field of CL1358+62 at z=0.33 are used to study the Fundamental Plane of galaxies based on a new, large sample of 53 galaxies. First, we have constructed the…
We present a detailed stellar population analysis for a sample of 24 early-type galaxies belonging to the rich cluster RXJ0152.7-1357 at z=0.83. We have derived the age, metallicity, abundance pattern and star formation history for each…
Tens of early type galaxies have been recently reported to possess prolate rotation, i.e. significant amount of rotation around the major axis, including two cases in the Local Group. Although expected theoretically, this phenomenon is…
Given any number field, we prove that there exist arbitrarily shaped constellations consisting of pairwise non-associate prime elements of the ring of integers. This result extends the celebrated Green-Tao theorem on arithmetic progressions…