Search results for "EIA"

X-ray variability of NGC 2516 stars in the XMM-Newton observations

2006

We present the characteristics of the X-ray variability of stars in the cluster NGC2516 as derived from XMM-Newton/EPIC/pn data. The X-ray variations on short (hours), medium (months), and long (years) time scales have been explored. We detected 303 distinct X-ray sources by analysing six EPIC/pn observations; 194 of them are members of the cluster. Stars of all spectral types, from the early-types to the late-M dwarfs, were detected. The Kolmogorov-Smirnov test applied to the X-ray photon time series shows that, on short time scales, only a relatively small fraction (ranging from 6% to 31% for dG and dF, respectively) of the members of NGC2516 are variable with a confidence level $\geq$99%…

Simultaneous Kepler/K2 and XMM‐Newton observations of superflares in the Pleiades

2019

Proceeding of a contributed talk given at the meeting: "TIME-DOMAIN ASTRONOMY: A HIGH ENERGY VIEW" held at ESAC, Madrid, 13 - 15 JUNE 2018 Together with coronal mass ejection, flares are the most energetic stellar magnetic events, ignited by a sudden release of magnetic energy, which triggers a cascade of interconnected phenomena, each resulting in emission in different bands. For this reason, flares are intrinsic multiwavelength phenomena. In particular, optical and soft X-ray emission probes two different events occurring during flares: the heating of plasma in the upper photosphere at the footpoints of the magnetic loops and the heating and cooling of the plasma confined in the loops in …

The X-ray Luminosity Distributions of the high-metallicity open cluster Blanco 1

2003

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 α  Per suggests a possible metallicity effect in dM stars.

Time evolution of X-ray coronal activity in PMS stars; a possible relation with the evolution of accretion disks

2003

We investigate the evolution of X-ray stellar activity from the age of the youngest known star forming regions (SFR), < 1Myr, to about 100 Myr, i.e. the zero age main sequence (ZAMS) for a ~ 1M_sun star. We consider five SFR of varying age (Rho Ophiuchi, the Orion Nebula Cluster, NGC 2264, Chamaeleon I, and Eta Chamaeleontis) and two young clusters (the Pleiades and NGC 2516). Optical and X-ray data for these regions are retrieved both from archival observations and recent literature, and reanalyzed here in a consistent manner so to minimize systematic differences in the results. We study trends of L_X and L_X/L_bol as a function of stellar mass and association age. For low mass stars (M…

Mass Segregation in the Open Cluster NGC 2422

2003

UBVRI photometry of the open cluster NGC2422 (age ~10 8  yr) down to a limiting magnitude V ≃ 19 is used to study the cluster spatial distribution and the luminosity and mass functions. From the Color-Magnitude Diagram (CMD), we obtained a list of candidate cluster members based on a photometric criterion. Using a comparison field region and an iterative procedure, a correction for contaminating field stars has been inferred in order to obtain the luminosity and the mass functions in the M=0.4 -3.5 M ⊙ range. By analyzing the spatial distribution, we infer that a non-negligible number of cluster stars lie outside our investigated region. We estimate a correction to the mass function of the …

X-ray spectral and timing characteristics of the stars in the young open cluster IC 2391

2005

We present X-ray spectral and timing analysis of members of the young open cluster IC 2391 observed with the XMM-Newton observatory. We detected 99 X-ray sources by analysing the summed data obtained from MOS1, MOS2 and pn detectors of the EPIC camera; 24 of them are members, or probable members, of the cluster. Stars of all spectral types have been detected, from the early-types to the late-M dwarfs. Despite the capability of the instrument to recognize up to 3 thermal components, the X-ray spectra of the G, K and M members of the cluster are well described with two thermal components (at kT$_1 \sim$ 0.3-0.5 keV and kT$_2 \sim$ 1.0-1.2 keV respectively) while the X-ray spectra of F members…

Rasgo de amor, que los estudiantes de la Universidad Literaria de Valencia, manifestaron á su idolatrado Rey el Sr. D. Fernando VII al encuentro en l…

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From Eunomia to Paideia: The Educating Nature of Law

2020

Education and Law are two of the institutions which most directly influence the configuration of the individual and of society. Furthermore, there is a close relationship between them in that each determines the development of the other. From their very beginnings, political and legal philosophy have asked what is Law, what is education and what should the relationship between them be. This chapter deals with the relationship between Law and education from this philosophical-practical perspective. It begins by illustrating the notable similarities between both and then goes on to address two questions: (1) whether Law should educate citizens in moral virtues; and (2) if the education of cit…

Schede materiali bronzei e ceramici nn.24-26, 80-84

2019

Schede di alcuni reperti in terracotta e in bronzo (lucerne, ceramica fine da mensa e un incensiere) provenienti da Pompei e da Torre del Greco, relativi alle donazioni che i Borbone fecero al Museo della Regia Università di Palermo, esposti nella Mostra “Palermo capitale del Regno. I Borbone e l’archeologia a Palermo, Napoli e Pompei”, Museo Archeologico Regionale A. Salinas, Palermo, 1/12/2018 – 30/06/2019. Catalogue of lamps, fine tableware and an incense burner from Pompeii and Torre del Greco, relating to the 'Donazioni borboniche' to the Museum of the University of Palermo, in the exhibition “Palermo capitale del Regno. I Borbone e l’archeologia a Palermo, Napoli e Pompei”, Museo Arch…

Institucions dels furs, y priuilegis del Regne de Valencia : eo summari e reportori de aquells

Sig.: [signe]6, A-Cc8, Ee1 Escut xil. del rei Jaume I a la port. - Capitals grav. - Frisos Text amb postil·les marginals. - Reclams