Search results for " sequence"
showing 10 items of 3643 documents
Synthesis and Biological Evaluation of a Multiantigenic Tn/TF-Containing Glycopeptide Mimic of the Tumor-Related MUC1 Glycoprotein
2006
ANCESTRALITY OR MORPHOLOGICAL CONVERGENCE IN THE MOLLISSIMA AND ITALICA GROUPS OF SILENE IN THE WESTERN MEDITERRANEAN BASIN
2010
The XMM-Newton Extended Survey of the Taurus Molecular Cloud (XEST)
2007
(abridged:) The XMM-Newton Extended Survey of the Taurus Molecular Cloud (XEST) surveys the most populated ~5 square degrees of the Taurus star formation region, using the XMM-Newton X-ray observatory to study the thermal structure, variability, and long-term evolution of hot plasma, to investigate the magnetic dynamo, and to search for new potential members of the association. Many targets are also studied in the optical, and high-resolution X-ray grating spectroscopy has been obtained for selected bright sources. The X-ray spectra have been coherently analyzed with two different thermal models (2-component thermal model, and a continuous emission measure distribution model). We present ov…
Spectral properties of X-ray bright variable sources in the Taurus Molecular Cloud
2006
We analyze 19 bright variable X-ray sources detected in the XMM-Newton Extended Survey of the Taurus Molecular Cloud (XEST), in order to characterize the variations with time of their coronal properties and to derive informations on the X-ray emitting structures. We performed time-resolved spectroscopy of the EPIC PN and MOS spectra of the XEST sources, using a model with one or two thermal components, and we used the time evolution of the temperatures and emission measures during the decay phase of flares to derive the size of the flaring loops. The light curves of the selected sources show different types of variability: flares, long-lasting decay or rise through the whole observation, sl…
High Energy Emission and its Variability in Young Stellar Objects
2019
Young stars show a variety of highly energetic phenomena, from accretion and outflow processes to hot coronal plasmas confined in their outer atmosphere, all regulated by the intense stellar magnetic fields. Many aspects on each of these phenomena are debated, but, most notably, their complex mutual interaction remains obscure. In this work I report how these phenomena are simultaneously responsible for the high-energy emission from young stars, with a special focus on the expected and observed variability in the X-ray band. Investigating variations in the X-ray emission from young stars allows us to pose constraints on flare and coronal plasma properties, coronal heating, accretion stream …
Activity-rotation relation in the young cluster h Per
2015
The activity-rotation relation in PMS stars is still an open issue. To bridge the gap between the well constrained case of MS stars and the puzzling case of very young PMS stars, we studied the activity-rotation relation in the young cluster h Persei. Because of its age (˜13 Myr) h Per contains both fast and slow rotators, allowing us therefore to test the different regimes of stellar dynamo. We analyzed a deep Chandra/ACIS-I observation to constrain the activity level of h Per members. Rotational periods were derived by tet{MorauxArtemenko2013}. From the comparison of the 1002 detected X-ray sources, and the 586 h Per members with measured rotational period, we obtained a final catalog of …
X-ray emission from the old CTTS MP Muscae
2007
We study the properties of X-ray emitting plasma of MP Mus, an old classical T Tauri star. XMM-Newton/RGS spectra allow us to measure the plasma electron density, which probes whether X-ray emission is produced in the accretion process. X-ray emission from MP Mus originates from high density cool plasma but a hot flaring component is also present, suggesting that both coronal magnetic activity and accretion contribute to the observed X-ray emission. From the soft part of the X-ray emission from MP Mus, mostly produced by plasma heated in the accretion shock, we derive the accretion parameters and the characteristics of the shock-heated plasma.
X-ray emission from an adolescent classical T Tauri star
2007
CSI 2264: Simultaneous optical and X-ray variability in the pre-main sequence stars of NGC 2264
2019
Context. Pre-main sequence stars are variable sources. In diskless stars this variability is mainly due to the rotational modulation of dark photospheric spots and active regions, as in main sequence stars even if associated with a stronger magnetic activity.Aims. We aim at analyzing the simultaneous optical and X-ray variability in these stars to unveil how the activity in the photosphere is connected with that in the corona, to identify the dominant surface magnetic activity, and to correlate our results with stellar properties, such as rotation and mass.Methods. We analyzed the simultaneous optical and X-ray variability in stars without inner disks (e.g., class III objects and stars with…
Counting Berg partitions via Sturmian words and substitution tilings
2013
We develop the connection of Berg partitions with special substitution tilings of two tiles. We obtain a new proof that the number of Berg partitions with a fixed connectivity matrix is equal to half of the sum of its entries, [12]. This approach together with the formula of Seebold [10], for the number of substitutions preserving a given Sturmian sequence, shows that all of the combinatorial substitutions can be realized geometrically as Berg partitions. We treat Sturmian tilings as intersection tilings of bi-partitions. Using the symmetries of bi-partitions we obtain geometrically the palindromic properties of Sturmian sequences (Theorem 3) established combinatorially by de Luca and Migno…