Magnetic field structure in single late-type giants: Beta Ceti in 2010 - 2012

The data were obtained using two spectropolarimeters - Narval at the Bernard Lyot Telescope, Pic du Midi, France, and ESPaDOnS at CFHT, Hawaii. Thirty-eight circularly-polarized spectra have been collected in the period June 2010 - January 2012. The Least Square Deconvolution method was applied for extracting high signal-to-noise ratio line profiles, from which we measure the surface-averaged longitudinal magnetic field Bl. Chromospheric activity indicators CaII K, H_alpha, CaII IR (854.2 nm) and radial velocity were simultaneously measured and their variability was analysed together with the behavior of Bl. The Zeeman Doppler Imaging (ZDI) inversion technique was employed for reconstruction of the large-scale magnetic field and two magnetic maps of Beta Ceti are presented for two periods (June 2010 - December 2010 and June 2011 - January 2012). Bl remains of positive polarity for the whole observational period. The behavior of the line activity indicators is in good agreement with the Bl variations. The two ZDI maps show a mainly axisymmetric and poloidal magnetic topology and a simple surface magnetic field configuration dominated by a dipole. Little evolution is observed between the two maps, in spite of a 1 yr interval between both subsets. We also use state-of-the-art stellar evolution models to constrain the evolutionary status of Beta Ceti. We derive a mass of 3.5 M_sun and propose that this star is already in the central-helium burning phase. Taking into account all our results and the evolutionary status of the star, we suggest that dynamo action alone may not be eficient enough to account for the high magnetic activity of Beta Ceti. As an alternate option, we propose that it may be an Ap star descendant presently undergoing central helium-burning and still exhibiting a remnant of the Ap star magnetic field.Comment: 10 pages; 5 figures; 3 table

Magnetic field structure in single late-type giants: The effectively single giant V390 Aur

We have studied the active giant V390 Aur using spectropolarimetry to obtain direct and simultaneous measurements of the magnetic field and the activity indicators in order to get a precise insight of its activity. We used the spectropolarimeter NARVAL at the Bernard Lyot Telescope (Observatoire du Pic du Midi, France) to obtain a series of Stokes I and Stokes V profiles. The Least Square deconvolution (LSD) technique was applied to detect the Zeeman signature of the magnetic field in each of our 13 observations and to measure its longitudinal component. We could also monitor the CaII K & H and IR triplet, as well as the H_alpha lines which are activity indicators. In order to reconstruct the magnetic field geometry of V390 Aur, we applied the Zeeman Doppler Imaging (ZDI) inversion method and present a map for the magnetic field. Based on the obtained spectra, we also refined the fundamental parameters of the star and the Li abundance. The ZDI revealed a structure in the radial magnetic field consisting of a polar magnetic spot of positive polarity and several negative spots at lower latitude. A high latitude belt is present on the azimuthal field map, indicative of a toroidal field close to the surface. It was found that the photometric period cannot fit the behaviour of the activity indicators formed in the chromosphere. Their behaviour suggests slower rotation compared to the photosphere, but our dataset is too short to be able to estimate the exact periods for them.Accepted for publication in A&A All these results can be explained in terms of an \alpha-\omega dynamo operation, taking into account the stellar structure and rotation properties of V390 Aur that we study using up to-date stellar models computed at solar metallicity. The calculated Rossby number also points to a very efficient dynamoComment: To appear in Astronomy & Astrophysics, 8 pages, 5 figure

Hypoxia-inducible-factor-1 in trauma and critical care

HIF-1 is a ubiquitous signaling molecule constantly expressed by the body, but is degraded during normoxic conditions. In hypoxic conditions, it persists and is active. Hypoxia is often associated with trauma due to interrupted blood flow, inflammation or other reasons, causing HIF-1 to be active in signaling and recovery. In this review, the function of HIF-1 is examined, as well as its clinical significance with regard to trauma and critical care. Using this information, we then identify potential points of treatment and intervention

Magnetism in Cool Evolved Stars: the M giants EK Bootis and β Pegasi

International audienceWe present a long-term spectropolarimetric study of the active M giants EK~Bootis (M5III) and ${\beta}$~Pegasi (M2.5II-III). For each star, the variability of the disk-averaged longitudinal component of the magnetic field (${B_l})$ is shown, along with the behavior of different spectral activity indicators. The possible nature of the secondary component of EK~Boo is discussed. We compare the observed variations in the activity proxies of each of the two giants and discuss possible physical explanations for the structure of their respective magnetic fields. For both objects, observations in linear polarisation are also presented and briefly discussed

Magnetism in Cool Evolved Stars: the M giants EK Bootis β\beta Pegasi

We present a long-term spectropolarimetric study of the active M giantsEK Bootis (M5III) and β Pegasi (M2.5II-III). For each star, the variability of the diskaveraged longitudinal component of the magnetic field (Bl) is shown, along with thebehavior of different spectral activity indicators. The possible nature of the secondarycomponent of EK Boo is discussed. We compare the observed variations in the activity proxies of each of the two giants and discuss possible physical explanations for thestructure of their respective magnetic fields. For both objects, observations in linear polarisation are also presented and briefly discussed

Magnetism in Cool Evolved Stars: the M giants EK Bootis and β Pegasi

International audienceWe present a long-term spectropolarimetric study of the active M giants EK~Bootis (M5III) and ${\beta}$~Pegasi (M2.5II-III). For each star, the variability of the disk-averaged longitudinal component of the magnetic field (${B_l})$ is shown, along with the behavior of different spectral activity indicators. The possible nature of the secondary component of EK~Boo is discussed. We compare the observed variations in the activity proxies of each of the two giants and discuss possible physical explanations for the structure of their respective magnetic fields. For both objects, observations in linear polarisation are also presented and briefly discussed