304 research outputs found
Massive Superparticle with Tensorial Central Charges
We construct the manifestly Lorenz-invariant formulation of the N=1 D=4
massive superparticle with tensorial central charges. The model contains a real
parameter k and at possesses one -symmetry while at k=0 the
number of -symmetry is two. The equivalence of the formulations at all
is obtained. The local transformations of -symmetry are
written out. It is considered the using of index spinor for construction of the
tensorial central charges. It is obtained the equivalence at classical level
between the massive D=4 superparticle with one -symmetry and the
massive D=4 spinning particleComment: 20 pages, Late
Weinberg propagator of a free massive particle with an arbitrary spin from the BFV-BRST path integral
The transition amplitude is obtained for a free massive particle of arbitrary
spin by calculating the path integral in the index-spinor formulation within
the BFV-BRST approach. None renormalizations of the path integral measure were
applied. The calculation has given the Weinberg propagator written in the
index-free form with the use of index spinor. The choice of boundary conditions
on the index spinor determines holomorphic or antiholomorphic representation
for the canonical description of particle/antiparticle spin.Comment: 31 pages, Latex, version published in Class. Quantum Gra
A 3D study of the photosphere of HD 99563 - I. Pulsation analysis
We have used high-speed spectroscopy of the rapidly oscillating Ap (roAp) star HD 99563 to study the pulsation amplitude and phase behaviour of elements in its stratified atmosphere over one 2.91-d rotation cycle. We identify spectral features related to patches in the surface distribution of chemical elements and study the pulsation amplitudes and phases as the patches move across the stellar disc. The variations are consistent with a distorted non-radial dipole pulsation mode. We measure a 1.6 km s−1 rotational variation in the mean radial velocities of Hα and argue that this is the first observation of Hα abundance spots caused by He settling through suppression of convection by the magnetic field on an oblique rotator, in support of a prime theory for the excitation mechanism of roAp star pulsation. We demonstrate that HD 99563 is the second roAp star to show aspect dependence of blue-to-red running wave line profile variations in Nd iii spots
The binary properties of the pulsating subdwarf B eclipsing binary PG 1336-018 (NY Virginis)
Aims. We present an unbiased orbit solution and mass determination of the components of the eclipsing binary PG1336−018 as a critical test for the formation scenarios of subdwarf B stars.
Methods. We obtained high-resolution time series VLT/UVES spectra and high-speed multicolour VLT/ULTRACAM photometric
observations of PG1336−018, a rapidly pulsating subdwarf B star in a short period eclipsing binary.
Results. Combining the radial velocity curve obtained from the VLT/UVES spectra with the VLT/ULTRACAM multicolour
lightcurves, we determined numerical orbital solutions for this eclipsing binary. Due to the large number of free parameters and their strong correlations, no unique solution could be found, only families of solutions. We present three solutions of equal statistical
significance, two of which are compatible with the primary having gone through a core He-flash and a common-envelope phase described by the α-formalism. These two models have an sdB primary of 0.466 M and 0.389 M, respectively. Finally, we report the detection of the Rossiter-McLaughlin effect for PG1336−018
Usefulness of electroanatomical mapping during transseptal endocardial left ventricular lead implantation
AimFailure rate to implant left ventricular (LV) lead
transvenously is 4-8% in cardiac resynchronization therapy (CRT)
patients. Epicardial lead placement is an alternative method and
if not applicable case reports and small series showed the
feasibility of endocardial LV lead implantation.
Electroanatomical mapping might be a useful tool to guide this
procedure.Methods and resultsFour patients had undergone
endocardial LV lead implantation after unsuccessful transvenous
implantation or epicardial LV lead dysfunction using the
transseptal approach. Electroanatomical mapping was used to mark
the location of the transseptal puncture. This location point
guided the mapping catheter from the subclavian access and
facilitated positioning of the LV lead at the adjacent latest
activation area of the left ventricle detected by activation
mapping. Endocardial active fixation LV leads were successfully
implanted in all patients with stable electrical parameters
immediately after implantation and over a mean follow-up of 18.3
months (lead impedance 520 +/- 177 vs. 439 +/- 119 Omega and
pacing threshold 0.8 +/- 0.2 V, 0.5 ms vs. 0.6 +/- 0.1 V, 0.5
ms, respectively). Patients were maintained on anticoagulation
therapy with a target international normalized ratio of 3.5-4.5
and did not show any thromboembolic, haemorrhagic events, or
infection. Echocardiography showed significant improvement of LV
systolic function with marked improvement of the functional
status.ConclusionsElectroanatomical mapping is a useful
technical tool to guide endocardial LV lead implantation. It
helps to identify the location of the transseptal puncture and
the use of activation mapping might facilitate location of the
optimal lead positions during CRT
Towards ensemble asteroseismology of the young open clusters Chi Persei and NGC 6910
As a result of the variability survey in Chi Persei and NGC6910, the number
of Beta Cep stars that are members of these two open clusters is increased to
twenty stars, nine in NGC6910 and eleven in Chi Persei. We compare pulsational
properties, in particular the frequency spectra, of Beta Cep stars in both
clusters and explain the differences in terms of the global parameters of the
clusters. We also indicate that the more complicated pattern of the variability
among B type stars in Chi Persei is very likely caused by higher rotational
velocities of stars in this cluster. We conclude that the sample of pulsating
stars in the two open clusters constitutes a very good starting point for the
ensemble asteroseismology of Beta Cep-type stars and maybe also for other
B-type pulsators.Comment: 4 pages, Astronomische Nachrichten, HELAS IV Conference, Arecife,
Lanzarote, Feb 2010, submitte
CoRoT\,102699796, the first metal-poor Herbig Ae pulsator: a hybrid Sct- Dor variable?
We present the analysis of the time series observations of CoRoT\,102699796
obtained by the CoRoT satellite that show the presence of five independent
oscillation frequencies in the range 3.6-5 c/d. Using spectra acquired with
FLAMES@VLT, we derive the following stellar parameters: spectral type F1V,
T=7000200 K, log(g)=, [M/H]=,
sin= km/s, L/L=21. Thus, for the first
time we report the existence of a metal poor, intermediate-mass PMS pulsating
star. Ground-based and satellite data are used to derive the spectral energy
distribution of CoRoT\,102699796 extending from the optical to mid-infrared
wavelengths. The SED shows a significant IR excess at wavelengths greater than
. We conclude that CoRoT\,102699796 is a young Herbig Ae (F1Ve) star
with a transitional disk, likely associated to the HII region [FT96]213.1-2.2.
The pulsation frequencies have been interpreted in the light of the
non-radial pulsation theory, using the LOSC code in conjunction with static and
rotational evolutionary tracks. A minimization algorithm was used to find the
best-fit model with M=1.84 M, T=6900 K which imply an
isochronal age of t2.5 Myr. This result is based on the interpretation of
the detected frequencies as -modes of low-moderate -value. To our
knowledge, this is the first time that such modes are identified in a
intermediate-mass PMS pulsating star. Since CoRoT\,102699796 lies in the region
of the HR diagram where the Sct and Dor instability strips
intersect, we argue that the observed pulsation characteristics are
intermediate between these classes of variables, i.e. CoRoT\,102699796 is
likely the first PMS hybrid Dor- Sct pulsator ever studied.Comment: 13 pages, 7 figures. Accepted for publication in Monthly Notices of
the RA
Multisite spectroscopic seismic study of the beta Cep star V2052 Oph: inhibition of mixing by its magnetic field
We used extensive ground-based multisite and archival spectroscopy to derive
observational constraints for a seismic modelling of the magnetic beta Cep star
V2052 Ophiuchi. The line-profile variability is dominated by a radial mode
(f_1=7.14846 d^{-1}) and by rotational modulation (P_rot=3.638833 d). Two
non-radial low-amplitude modes (f_2=7.75603 d^{-1} and f_3=6.82308 d^{-1}) are
also detected. The four periodicities that we found are the same as the ones
discovered from a companion multisite photometric campaign (Handler et al.
2012) and known in the literature. Using the photometric constraints on the
degrees l of the pulsation modes, we show that both f_2 and f_3 are prograde
modes with (l,m)=(4,2) or (4,3). These results allowed us to deduce ranges for
the mass (M \in [8.2,9.6] M_o) and central hydrogen abundance (X_c \in
[0.25,0.32]) of V2052 Oph, to identify the radial orders n_1=1, n_2=-3 and
n_3=-2, and to derive an equatorial rotation velocity v_eq \in [71,75] km
s^{-1}. The model parameters are in full agreement with the effective
temperature and surface gravity deduced from spectroscopy. Only models with no
or mild core overshooting (alpha_ov \in [0,0.15] local pressure scale heights)
can account for the observed properties. Such a low overshooting is opposite to
our previous modelling results for the non-magnetic beta Cep star theta Oph
having very similar parameters, except for a slower surface rotation rate. We
discuss whether this result can be explained by the presence of a magnetic
field in V2052 Oph that inhibits mixing in its interior.Comment: 12 pages, 6 figures and 5 tables; accepted for publication in MNRAS
on 2012 August 1
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