4,895 research outputs found
Cosmic abundances: The impact of stellar duplicity
The mass-transfer scenario links chemical peculiarities with stellar
duplicity for an increasing number of stellar classes (classical and dwarf
barium stars, subgiant and giant CH stars, S stars without technetium, yellow
symbiotic stars, WIRRING stars, Abell-35-like nuclei of planetary nebulae...).
Despite these successes, the mass-transfer scenario still faces several
problems: What is the mass-transfer mode? Why orbital elements of dwarf barium
stars do not fully match those of the classical barium stars? What is the
origin of the few non-binary stars among dwarf barium stars? The paper reviews
these open questions.Comment: 14 pages, 4 figures, to appear in `Cosmic Abundances as Records of
Stellar Evolution and Nucleosynthesis', edited by F.N. Bash, T.G. Barnes, ASP
Conf. Ser., in pres
The Henize sample of S stars. I. The technetium dichotomy
This paper is the first one in a series investigating the properties of the S
stars belonging to the Henize sample (205 S stars with delta<-25 deg. and
R<10.5) in order to derive the respective properties (like galactic
distribution and relative frequencies) of intrinsic (i.e. genuine asymptotic
giant branch) S stars and extrinsic (i.e. post mass-transfer binary) S stars.
High-resolution (R=30 000 to 60 000) spectra covering the range 4230-4270AA
have been obtained for 76 S stars, 8 M stars and 2 symbiotic stars. The 4262AA
and 4238AA blends involving a Tc I line were analysed separately and yield
consistent conclusions regarding the presence or absence of technetium. Only
one `transition' case (Hen 140 = HD 120179, a star where only weak lines of
technetium are detectable) is found in our sample. A resolution greater than R
=30 000 is clearly required in order to derive unambiguous conclusions
concerning the presence or absence of technetium. The Tc/no Tc dichotomy will
be correlated with radial velocity and photometric data in a forthcoming paper.Comment: 10 pages, 5 figures, Latex, accepted for publication in Astronomy and
Astrophysics main journal. Also available at http://astro.ulb.ac.be
The Henize sample of S stars: IV. New symbiotic stars
The properties of the few symbiotic stars detected among the 66 binary S
stars from the Henize sample are discussed. Two stars (Hen 18 and Hen 121)
exhibit both a strong blue-violet continuum and strong H_alpha emission (FWHM
of 70 km/s), whereas Hen 134 and 137 exhibit weak H_alpha emission. The H_alpha
profiles are typical of non-dusty symbiotic stars belonging to class S-3 as
defined by Van Winckel et al. (1993, A&AS 102, 401). In that class as in the
Henize symbiotic S stars, He I, [N II] or [S II] emission lines are absent,
suggesting that the nebular density is high but the excitation rather low. The
radial velocity of the centre of the H_alpha emission is identical to that of
the companion star (at least for Hen 121 where this can be checked from the
available orbital elements), thus suggesting that the H_alpha emission
originates from gas moving with the companion star. For Hen 121, this is
further confirmed by the disappearance of the ultraviolet Balmer continuum when
the companion is eclipsed by the S star. Hen 121 is thus the second eclipsing
binary star discovered among extrinsic S stars (the first one is HD 35155). A
comparison of the available data on orbital periods and H_alpha emission leads
to the conclusion that H_alpha emission in S stars seems to be restricted to
binary systems with periods in the range 600 - 1000 d, in agreement with the
situation prevailing for red symbiotic stars (excluding symbiotic novae).
Symbiotic S stars are found among the most evolved extrinsic S stars.Comment: 10 pages, 9 figures, accepted for publication in Astronomy and
Astrophysic
A CORAVEL radial-velocity monitoring of giant Ba and S stars: spectroscopic orbits and intrinsic variations
This paper provides orbital parameters for 38 barium stars and 10 extrinsic S
stars derived from a decade-long CORAVEL monitoring. Lower bounds on the
orbital period (generally exceeding 10 y) have been obtained for 10 more
systems. Mira S, SC and (Tc-poor) C stars have also been monitored and show
intrinsic radial-velocity variations due to atmospheric phenomena. Tentative
orbital solutions are proposed for 3 stars (S UMa, X Cnc, BD-08:1900) where the
velocity and photometric periods are different. Three stars (RZ Peg, SS Vir and
R CMi) exhibit radial-velocity variations synchronous with the light
variations. Pseudo-orbital solutions have been derived for those stars. In the
case of RZ Peg, a line-doubling phenomenon is observed near maximum light, and
probably reflects the shock wave propagating through the photosphere.Comment: Astronomy & Astrophysics Supplements, 20 pages, 8 figures, 8 tables
(LaTeX). Also available at:
http://obswww.unige.ch/~udry/cine/barium/barium.htm
Spectroscopic binaries among AGB stars from HERMES/Mercator: the case of V Hya
We report on our search for spectroscopic binaries among a sample of AGB
stars. Observations were carried out in the framework of the monitoring of
radial velocities of (candidate) binary stars performed at the Mercator 1.2m
telescope, using the HERMES spectrograph. We found evidence for duplicity in UV
Cam, TU Tau, BL Ori, VZ Per, T Dra, and V Hya. This short communication focus
on V Hya, found to behave like RV Tau of the b subtype, which are binaries
surrounded by a disc.Comment: Poster presented at IAU Symp. 343 "Why Galaxies Care About AGB
Stars", Vienna, august 201
Tiny Microbes, Big Data:Gut Microbiota Profiling for Clinical Diagnostics
Savelkoul, P.H.M. [Promotor]Bodegraven, A.A. van [Copromotor]Budding, A.E. [Copromotor
Tomography of the red supergiant star {\mu} Cep
A tomographic method, aiming at probing velocity fields at depth in stellar
atmospheres, is applied to the red supergiant star {\mu} Cep and to snapshots
of 3D radiative-hydrodynamics simulation in order to constrain atmospheric
motions and relate them to photometric variability.Comment: 2 pages, 2 figures, accepted as Proceedings of IAU Symposium No. 343,
201
Does Adalimumab Improve Symptoms in Patients with Moderate to Severe Hidradenitis Suppurativa?
OBJECTIVE: The objective of this selective EBM review is to determine whether or not “Does Adalimumab improve symptoms in patients with moderate to severe Hidradenitis Suppurativa?”
STUDY DESIGN: A systematic review of three peer-reviewed articles published between 2011 and 2016 which present patient oriented evidence.
DATA SOURCES: Review incorporated analysis of two randomized controlled trials (RCTs) and one open label prospective trial. Studies were selected based upon the relevance to the clinical question, does adalimumab usage improve symptoms in individuals with moderate to severe hidradenitis suppurativa.
OUTCOMES MEASURED: The outcomes measured focused on patient reported reduction in hidradenitis suppurativa symptoms. Two studies analyzed outcomes using patient reported Dermatology Life Quality Index (DLQI) scores, which take into account both physical and psychological disease burden as reported by the patient. The third study evaluated outcomes by analyzing the percentage of participants whom reported at least a 30% reduction in pain scores following adalimumab usage.
RESULTS: The open label trial completed by Sotiriou E, Goussi C, Lallas A, et al. revealed a significant improvement (P= 0.001) in patient reported DLQI scores following adalimumab usage for 24 weeks when compared to their initial DLQI scores. The study completed by Miller I, Lynggaard CD, Lophaven S, et al. failed to show statistically significant improvement in DLQI scores of patients receiving adalimumab compared to those receiving a placebo. The study by Kimball AB, Okun MM, Williams DA, et al. revealed inconsistent results concerning patient reported pain improvement with adalimumab use versus the use of a placebo.
CONCLUSION: Review of the three studies selected revealed inconclusive results. Though the results were inconsistent between studies, the presence of positive results in two of the studies indicates that further investigation of the efficacy of adalimumab use for hidradenitis suppurativa is warranted. Results from the studies analyzed indicate further research should also be carried out to evaluate the efficacy of simultaneous adalimumab and conventional therapeutic usage
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