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The <i>Gaia</i>-ESO survey: the inner disk intermediate-age open cluster NGC 6802
Tang, B.,Geisler, D.,Friel, E.,Villanova, S.,Smiljanic, R.,Casey, A. R.,Randich, S.,Magrini, L.,San Roman, I.,Muñ,oz, C.,Cohen, R. E.,Mauro, F.,Bragaglia, A.,Donati, P.,Tautvaiš,ien*error*& Springer-Verlag 2017 Astronomy and astrophysics Vol.601 No.-
Placing the Spotted T Tauri Star LkCa 4 on an HR Diagram
Gully-Santiago, Michael A.,Herczeg, Gregory J.,Czekala, Ian,Somers, Garrett,Grankin, Konstantin,Covey, Kevin R.,Donati, J. F.,Alencar, Silvia H. P.,Hussain, Gaitee A. J.,Shappee, Benjamin J.,Mace, Gre American Astronomical Society 2017 The Astrophysical journal Vol.836 No.2
<P>Ages and masses of young stars are often estimated by comparing their luminosities and effective temperatures to pre-main-sequence stellar evolution tracks, but magnetic fields and starspots complicate both the observations and evolution. To understand their influence, we study the heavily spotted weak-lined T-Tauri star LkCa 4 by searching for spectral signatures of radiation originating from the starspot or starspot groups. We introduce a new methodology for constraining both the starspot filling factor and the spot temperature by fitting two-temperature stellar atmosphere models constructed from PHOENIX synthetic spectra to a high-resolution near-IR IGRINS spectrum. Clearly discernable spectral features arise from both a hot photospheric component T-hot similar to 4100 K and a cool component T-cool similar to 2700-3000 K, which covers similar to 80% of the visible surface. This mix of hot and cool emission is supported by analyses of the spectral energy distribution, rotational modulation of colors and of TiO band strengths, and features in low-resolution optical/near-IR spectroscopy. Although the revised effective temperature and luminosity make. LkCa 4 appear to be. much younger and of much. lower mass than previous estimates from unspotted stellar evolution models, appropriate estimates will require the production and adoption of spotted evolutionary models. Biases from starspots likely afflict most fully convective young stars and contribute to uncertainties in ages and age spreads of open clusters. In some spectral regions, starspots act as a featureless 'veiling' continuum owing to high rotational broadening and heavy line blanketing in cool star spectra. Some evidence is also found for an anticorrelation between the velocities of the warm and cool components.</P>
European 1: A globally important clonal complex of Mycobacterium bovis
Smith, N.H.,Berg, S.,Dale, J.,Allen, A.,Rodriguez, S.,Romero, B.,Matos, F.,Ghebremichael, S.,Karoui, C.,Donati, C.,Machado, A.d.C.,Mucavele, C.,Kazwala, R.R.,Hilty, M.,Cadmus, S.,Ngandolo, B.N.R.,Habt Elsevier Science 2011 Infection, genetics and evolution Vol.11 No.6
We have identified a globally important clonal complex of Mycobacterium bovis by deletion analysis of over one thousand strains from over 30 countries. We initially show that over 99% of the strains of M. bovis, the cause of bovine tuberculosis, isolated from cattle in the Republic of Ireland and the UK are closely related and are members of a single clonal complex marked by the deletion of chromosomal region RDEu1 and we named this clonal complex European 1 (Eu1). Eu1 strains were present at less than 14% of French, Portuguese and Spanish isolates of M. bovis but are rare in other mainland European countries and Iran. However, strains of the Eu1 clonal complex were found at high frequency in former trading partners of the UK (USA, South Africa, New Zealand, Australia and Canada). The Americas, with the exception of Brazil, are dominated by the Eu1 clonal complex which was at high frequency in Argentina, Chile, Ecuador and Mexico as well as North America. Eu1 was rare or absent in the African countries surveyed except South Africa. A small sample of strains from Taiwan were non-Eu1 but, surprisingly, isolates from Korea and Kazakhstan were members of the Eu1 clonal complex. The simplest explanation for much of the current distribution of the Eu1 clonal complex is that it was spread in infected cattle, such as Herefords, from the UK to former trading partners, although there is evidence of secondary dispersion since. This is the first identification of a globally dispersed clonal complex M. bovis and indicates that much of the current global distribution of this important veterinary pathogen has resulted from relatively recent International trade in cattle.