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A fluorescing spot on the temple: a helpful reminder for a detailed history and physical exam
We discuss a woman with a history of non-melanoma skin cancer who presented with a new erythematous macule on her right temple. On examination with Wood lamp the well-demarcated macule fluoresced pink making neoplasm unlikely. Further history and physical examination suggested an inadvertent ink stain and the patient was spared a biopsy highlighting the importance of eliciting a good history and performing a detailed physical examination with additional tools such as a Wood lamp when necessary
Stochastic excitation of gravity waves in rapidly rotating massive stars
Stochastic gravity waves have been recently detected and characterised in
stars thanks to space asteroseismology and they may play an important role in
the evolution of stellar angular momentum. In this context, the observational
study of the CoRoT hot Be star HD 51452 suggests a potentially strong impact of
rotation on stochastic excitation of gravito-inertial waves in rapidly rotating
stars. In this work, we present our results on the action of the Coriolis
acceleration on stochastic wave excitation by turbulent convection. We study
the change of efficiency of this mechanism as a function of the waves' Rossby
number and we demonstrate that the excitation presents two different regimes
for super-inertial and sub-inertial frequencies. Consequences for rapidly
rotating early-type stars and the transport of angular momentum in their
interiors are discussed.Comment: 2 pages, 1 figure, IAU 307 symposium proceedings, 'New windows on
massive stars: asteroseismology, interferometry, and spectropolarimetry',
Eds. G. Meynet, C. Georgy, J.H. Groh & Ph. Ste
Asteroseismology and spectropolarimetry: opening new windows on the internal dynamics of massive stars
In this article, we show how asteroseismology and spectropolarimetry allow to
probe dynamical processes in massive star interiors. First, we give a summary
of the state-of-the-art. Second, we recall the MHD mechanisms that take place
in massive stars. Next, we show how asteroseimology gives strong constraints on
the internal mixing and transport of angular momentum while spectropolarimetry
allows to unravel the role played by magnetic fields.Comment: 5 pages, 1 figure, IAU 307 symposium proceedings, New windows on
massive stars: asteroseismology, interferometry, and spectropolarimetry, Eds.
G. Meynet, C. Georgy, J. H. Groh, and P. Ste
Magnetic fields in early-type stars
For several decades we have been cognizant of the presence of magnetic fields
in early-type stars, but our understanding of their magnetic properties has
recently (over the last decade) expanded due to the new generation of
high-resolution spectropolarimeters (ESPaDOnS at CFHT, Narval at TBL, HARPSpol
at ESO). The most detailed surface magnetic field maps of intermediate-mass
stars have been obtained through Doppler imaging techniques, allowing us to
probe the small-scale structure of these stars. Thanks to the effort of large
programmes (e.g. the MiMeS project), we have, for the first time, addressed key
issues regarding our understanding of the magnetic properties of massive (M > 8
M_sun) stars, whose magnetic fields were only first detected about fifteen
years ago. In this proceedings article we review the spectropolarimetric
observations and statistics derived in recent years that have formed our
general understanding of stellar magnetism in early-type stars. We also discuss
how these observations have furthered our understanding of the interactions
between the magnetic field and stellar wind, as well as the consequences and
connections of this interaction with other observed phenomena.Comment: 8 pages, 2 figures. To appear in the proceedings of the IAUS 305 -
Polarimetry: From the sun to stars and stellar environment
XMM-Newton observations of MR Vel/RX J0925.7-4758
We report on XMM-Newton observations of the galactic supersoft X-ray source
RX J0925.7-4758. The RGS spectrum exhibits a wealth of spectral features from
iron and oxygen. XMM-Newton data confirm the finding of previous Chandra
HETGS/MEG observations that NLTE models of hot white dwarf atmospheres fail to
represent the complex spectrum. There are clear evidences for P Cygni profiles
with wind velocities of up to 2000 km/s. Small flux variations with time scales
larger than 1000s are present. The strongest power is at ~ 0.21d, a period
close to that seen in V band optical light curves. A detailed analysis of the
associated changes in the RGS and EPIC pn spectra hint at a mostly grey
mechanism suggesting a variation of the visibility of the white dwarf due to
occulting material in the accretion disk. Finally, we detect radial velocity
changes of 173 +/- 47 km/s between two RGS observations obtained half an
orbital cycle apart. The amplitude of the RGS velocity shift is consistent with
that of the optical He II 4686 and thus supports the idea that most of the He
II optical line emission arises from the accretion disk.Comment: Accepted for publication in A&A (8 pages and 9 figures
Magneto-asteroseismology of massive magnetic pulsators
Simultaneously and coherently studying the large-scale magnetic field and the
stellar pulsations of a massive star provides strong complementary diagnostics
suitable for detailed stellar modelling. This hybrid method is called
magneto-asteroseismology and permits the determination of the internal
structure and conditions within magnetic massive pulsators, for example the
effect of magnetism on non-standard mixing processes. Here, we overview this
technique, its requirements, and list the currently known suitable stars to
apply the method.Comment: 5 pages, 1 table, IAUS 329 conference proceeding
Discovery of a very weak magnetic field on the Am star Alhena
Alhena ( Gem) was observed in the frame of the BRITE (BRIght Target
Explorer) spectropolarimetric survey, which gathers high resolution, high
signal-to-noise, high sensitivity, spectropolarimetric observations of all
stars brighter than V=4 to combine seismic and spectropolarimetric studies of
bright stars.
We present here the discovery of a very weak magnetic field \textbf{on} the
Am star Alhena, thanks to very high signal-to-noise spectropolarimetric data
obtained with Narval at T\'elescope Bernard Lyot (TBL). All previously studied
Am stars show the presence of ultra-weak (sub-Gauss) fields with Zeeman
signatures with an unexpected prominent positive lobe. However, Alhena presents
a slightly stronger (but still very weak, only a few Gauss) field with normal
Zeeman signatures with a positive and negative lobe, as found in stronger field
(hundreds or thousands of Gauss) stars. It is the first detection of a normal
magnetic signature in an Am star.
Alhena is thus a very interesting object, which might provide the clue to
understanding the peculiar shapes of the magnetic signatures of the other Am
stars.Comment: letter accepted by MNRA
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