Search results for "clusters"
showing 10 items of 1274 documents
Fission yield measurements at IGISOL
2016
The fission product yields are an important characteristic of the fission process. In fundamental physics, knowledge of the yield distributions is needed to better understand the fission process. For nuclear energy applications good knowledge of neutroninduced fission-product yields is important for the safe and efficient operation of nuclear power plants. With the Ion Guide Isotope Separator On-Line (IGISOL) technique, products of nuclear reactions are stopped in a buffer gas and then extracted and separated by mass. Thanks to the high resolving power of the JYFLTRAP Penning trap, at University of Jyväskylä, fission products can be isobarically separated, making it possible to measure rela…
XMM sources in Blanco 1
2005
We present an X-ray study of the high metallicity young open cluster Blanco 1 based on XMM-Newton data. X-ray spectroscopy of cluster members is presented for the first time as well as new X-ray distribution functions of late-type stars. We detected all known dF and dG stars in the EPIC field and 80% and 90% of dK and dM stars, respectively. The X-ray spectral analysis of the X-ray brightest cluster stars and X-ray color analysis of a larger sample show that a model with two temperatures (at about 0.3 and 1keV) explains the quiescent activity phase spectra. We discuss also the nature of unidentified X-ray sources in the observed region and their X-ray spectral properties. Cone search capabi…
Chandra X-ray sources in Orion Nebula Cluster
2003
In this first of two companion papers on the Orion Nebula Cluster (ONC), we present our analysis of a 63ks Chandra HRC-I observation that yielded 742 X-ray detections within the 30'x30' field of view. To facilitate our interpretation of the X-ray image, here we collect a multiwavelength catalog of nearly 2900 known objects in the region by combining 17 different catalogs from the recent literature. We define two reference groups: an infrared sample, containing all objects detected in the K band, and an optical sample comprising low-extinction, well-characterized ONC members. We show for both samples that field object contamination is generally low. Our X-ray sources are primarily low-mass O…
X-ray Luminosities in Blanco 1
2005
We present X-ray Luminosity Distributions (XLDs) of late-type members (dF, dG, dK, dM) of the Blanco 1 cluster, based on ROSAT-HRI data and new astrometric-photometric membership obtained from the GSC-II project. For the first time we present the XLD of dM stars of this cluster. The high metallicity of Blanco 1 allows us to investigate the role of chemical composition on the coronal emission of late-type stars. Comparison between X-ray Luminosity Distributions of Blanco 1 and Pleiades, NGC 2516 and {alpha} Per suggests a possible metallicity effect in dM stars. Cone search capability for table J/A+A/399/919/tablea1 (Optical, infrared and X-ray band properties of Blanco 1 members in the comb…
BVI photometry in NGC 6611
2007
VizieR online Data Catalogue associated with article published in journal Astronomy & Astrophysics with title 'Correlation between the spatial distribution of circumstellar disks and massive stars in the open cluster NGC 6611. Compiled catalog and cluster parameters.' (bibcode: 2007A&A...462..245G)
BVI & JHK photometry of NGC 3960
2004
VizieR online Data Catalogue associated with article published in journal Astronomy & Astrophysics with title 'Parameter properties and stellar population of the old open cluster NGC 3960.' (bibcode: 2004A&A...417..945P)
Mapping accretion variability in NGC 2264
2014
Our study aims at characterizing the accretion properties of several hundred members of the star-forming region NGC 2264 (3Myr). We performed a deep u,g,r,i mapping of the cluster with CFHT/MegaCam, and monitored the simultaneous u+r variability of its members over a baseline of two weeks. Stellar parameters are determined homogeneously for about 750 monitored young objects, 40% of which are accreting T Tauri stars. Accretion properties and accretion variability are investigated and characterized from UV excess measurements. Non-accreting members of the cluster define the reference UV emission level over which flux excess is detected and measured. Cone search capability for table J/A+A/570/…
X-ray sources in NGC 752
2008
While observational evidence shows that most of the decline in a star's X-ray activity occurs between the age of the Hyades (~8x10^8yr) and that of the Sun, very little is known about the evolution of stellar activity between these ages. To gain information on the typical level of coronal activity at a star's intermediate age, we studied the X-ray emission from stars in the 1.9Gyr old open cluster NGC 752. We analysed a ~140ks Chandraobservation of NGC 752 and a ~50ks XMM-Newtonobservation of the same cluster. We detected 262 X-ray sources in the Chandra data and 145 sources in the XMM-Newton observation. Around 90% of the catalogued cluster members within Chandra's field-of-view are detect…
PMS stars in h Per
2016
VizieR online Data Catalogue associated with article published in journal Astronomy & Astrophysics with title 'Supersaturation and activity-rotation relation in PMS stars: the young cluster h Per.' (bibcode: 2016A&A...589A.113A)
XMM survey of NGC 2516
2007
VizieR online Data Catalogue associated with article published in journal Astronomy & Astrophysics with title 'Deep X-ray survey of the young open cluster NGC 2516 with XMM-Newton.' (bibcode: 2006A&A...450..993P)