554 research outputs found
Photometry of two DQ white dwarfs - search for spots
Aims. The intensity profiles of the C_2 Swan bands in cool DQ white dwarfs
cannot be adequately fitted with models that otherwise succesfully reproduce
spectral features of the molecule CH in these stars. Initial modelling showed
that a two-component atmosphere in the style of a spot might be able to solve
the problem.
Methods. We photometrically observed the two cool DQ white dwarfs GJ1117 and
EGGR78 to search for variability caused by stellar spots.
Results. We have not found any such variability, but we estimate the effects
of hypothetical spots on lightcurves. We also estimate detection probabilities
for spots in different configurations. Alternative explanations of the problem
are needed and briefly discussed.Comment: 5 pages, 6 figures, published in A&
Spectropolarimetric observations of cool DQ white dwarfs
Following our recent discovery of a new magnetic DQ white dwarf (WD) with CH
molecular features, we report the results for the rest of the DQ WDs from our
survey. We use high signal-to-noise spectropolarimetric data to search for
magnetic fields in a sample of 11 objects. One object in our sample,
WD1235+422, shows the signs of continuum circular polarization that is similar
to some peculiar DQs with unidentified molecular absorption bands, but the low
S/N and spectral resolution of these data make more observations necessary to
reveal the true nature of this object.Comment: 4 pages, 4 figures. Accepted for publication in Astronomy &
Astrophysic
Π‘ΠΎΠΎΠ±ΡΠ΅Π½ΠΈΠ΅ ΠΎ ΡΠ΅ΡΡΠ°ΠΊΡΠΈΠΈ: Β«ΠΠΌΠΌΡΠ½ΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΠΊΡΠΈΡΠ΅ΡΠΈΠΈ ΠΏΡΠΎΠ³Π½ΠΎΠ·ΠΈΡΠΎΠ²Π°Π½ΠΈΡ Π·Π°ΠΌΠ΅Π΄Π»Π΅Π½Π½ΠΎΠΉ ΠΊΠΎΠ½ΡΠΎΠ»ΠΈΠ΄Π°ΡΠΈΠΈ ΠΊΠΎΡΡΠ½ΠΎΠΉ ΡΠΊΠ°Π½ΠΈΒ», ΠΆΡΡΠ½Π°Π» Β«Π’ΡΠ°Π²ΠΌΠ°ΡΠΎΠ»ΠΎΠ³ΠΈΡ ΠΈ ΠΎΡΡΠΎΠΏΠ΅Π΄ΠΈΡ Π ΠΎΡΡΠΈΠΈΒ». 2009, β 2, Π‘. 59β66
The article Immunologic criteria of prediction of bone delayed union published in Traumatology and Orthopedics of Russia (2009, N 2) by O.V. Berdyugina, K.A. Berdyugin is a duplicate of the article Immunological monitoring of slow down ostheogenesis published in Medical Immunology. 2009;(3-4):371-378. That was the reason for retraction.
Revealed April 20, 2022 by the Editorial Board.Π‘ΡΠ°ΡΡΡ ΠΠΌΠΌΡΠ½ΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΠΊΡΠΈΡΠ΅ΡΠΈΠΈ ΠΏΡΠΎΠ³Π½ΠΎΠ·ΠΈΡΠΎΠ²Π°Π½ΠΈΡ Π·Π°ΠΌΠ΅Π΄Π»Π΅Π½Π½ΠΎΠΉ ΠΊΠΎΠ½ΡΠΎΠ»ΠΈΠ΄Π°ΡΠΈΠΈ ΠΊΠΎΡΡΠ½ΠΎΠΉ ΡΠΊΠ°Π½ΠΈ, ΠΎΠΏΡΠ±Π»ΠΈΠΊΠΎΠ²Π°Π½Π½Π°Ρ Π² ΠΆΡΡΠ½Π°Π»Π΅ Π’ΡΠ°Π²ΠΌΠ°ΡΠΎΠ»ΠΎΠ³ΠΈΡ ΠΈ ΠΎΡΡΠΎΠΏΠ΅Π΄ΠΈΡ Π ΠΎΡΡΠΈΠΈ (2009, β 2), Π°Π²ΡΠΎΡΠ°ΠΌΠΈ ΠΊΠΎΡΠΎΡΠΎΠΉ ΡΠ²Π»ΡΡΡΡΡ Π.Π. ΠΠ΅ΡΠ΄ΡΠ³ΠΈΠ½Π°, Π.Π. ΠΠ΅ΡΠ΄ΡΠ³ΠΈΠ½, ΠΏΡΠ΅Π΄ΡΡΠ°Π²Π»ΡΠ΅Ρ ΡΠΎΠ±ΠΎΠΉ Π΄ΡΠ±Π»ΠΈΠΊΠ°Ρ ΡΡΠ°ΡΡΠΈ Π.Π. ΠΠ΅ΡΠ΄ΡΠ³ΠΈΠ½ΠΎΠΉ ΠΠΌΠΌΡΠ½ΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠΉ ΠΌΠΎΠ½ΠΈΡΠΎΡΠΈΠ½Π³ Π·Π°ΠΌΠ΅Π΄Π»Π΅Π½Π½ΠΎΠ³ΠΎ ΠΎΡΡΠ΅ΠΎΠ³Π΅Π½Π΅Π·Π°, ΠΎΠΏΡΠ±Π»ΠΈΠΊΠΎΠ²Π°Π½Π½ΠΎΠΉ Π² ΠΆΡΡΠ½Π°Π»Π΅ ΠΠ΅Π΄ΠΈΡΠΈΠ½ΡΠΊΠ°Ρ ΠΈΠΌΠΌΡΠ½ΠΎΠ»ΠΎΠ³ΠΈΡ. 2008, Π’. 10, β 4-5, Π‘. 371-378. Π ΡΠ²ΡΠ·ΠΈ Ρ ΡΡΠΈΠΌ ΡΠΊΠ°Π·Π°Π½Π½Π°Ρ ΡΡΠ°ΡΡΡ ΠΎΡΠΎΠ·Π²Π°Π½Π° Ρ ΠΏΡΠ±Π»ΠΈΠΊΠ°ΡΠΈΠΈ.
ΠΡΡΠ²Π»Π΅Π½ΠΎ 20/04/22 ΡΠ΅Π΄ΠΊΠΎΠ»Π»Π΅Π³ΠΈΠ΅ΠΉ ΠΆΡΡΠ½Π°Π»Π°
Fluidity Onset in Graphene
Viscous electron fluids have emerged recently as a new paradigm of
strongly-correlated electron transport in solids. Here we report on a direct
observation of the transition to this long-sought-for state of matter in a
high-mobility electron system in graphene. Unexpectedly, the electron flow is
found to be interaction-dominated but non-hydrodynamic (quasiballistic) in a
wide temperature range, showing signatures of viscous flows only at relatively
high temperatures. The transition between the two regimes is characterized by a
sharp maximum of negative resistance, probed in proximity to the current
injector. The resistance decreases as the system goes deeper into the
hydrodynamic regime. In a perfect darkness-before-daybreak manner, the
interaction-dominated negative response is strongest at the transition to the
quasiballistic regime. Our work provides the first demonstration of how the
viscous fluid behavior emerges in an interacting electron system.Comment: 8pgs, 4fg
Evidence for Extremely High Dust Polarization Efficiency in NGC 3184
Recent studies have found the Type II-plateau supernova (SN) 1999gi to be
highly polarized (p_max = 5.8%, where p_max is the highest degree of
polarization measured in the optical bandpass; Leonard & Filippenko 2001) and
minimally reddened (E[B-V] = 0.21 +/- 0.09 mag; Leonard et al. 2002). From
multiple lines of evidence, including the convincing fit of a ``Serkowski''
interstellar polarization (ISP) curve to the continuum polarization shape, we
conclude that the bulk of the observed polarization is likely due to dust along
the line of sight (l-o-s), and is not intrinsic to SN 1999gi. We present new
spectropolarimetric observations of four distant Galactic stars close to the
l-o-s to SN 1999gi (two are within 0.02 degrees), and find that all are null to
within 0.2%, effectively eliminating Galactic dust as the cause of the high
polarization. The high ISP coupled with the low reddening implies an
extraordinarily high polarization efficiency for the dust along this l-o-s in
NGC 3184: ISP / E(B-V) = 31^{+22}_{-9} % mag^{-1}. This is inconsistent with
the empirical Galactic limit (ISP / E[B-V] < 9% mag^{-1}), and represents the
highest polarization efficiency yet confirmed for a single sight line in either
the Milky Way or an external galaxy.Comment: 27 pages, accepted for publication by the Astronomical Journa
High-precision broadband linear polarimetry of early-type binaries IV. Binary system of DH Cephei in the open cluster of NGC 7380
DH~Cephei is a well known massive O+O-type binary system on the northern sky,
residing in the young open cluster NGC~7380. Our high-precision multi-band
polarimetry has clearly revealed that variations of linear polarizations in
this system are synchronous with the phase of the orbital period. We have used
the observed variations of Stokes parameters and to derive the orbital
inclination , orientation , and the direction of rotation. In order
to determine the contribution from interstellar polarization, we have carried
out new observations of polarization of field stars with precisely measured
parallaxes.
The variations of Stokes parameters in all three , , and passbands
clearly exhibit an unambiguous periodic signal at 1.055 d with the amplitude of
variations which corresponds to half of known orbital period of
2.11 d. This type of polarization variability is expected for a binary system
with light scattering material distributed symmetrically with respect to the
orbital plane. Even though most of the observed polarization (2) is
of interstellar origin, about one third of it is due to the intrinsic
component. In addition to the regular polarization variability, there is a
non-periodic component, strongest in the passband. We obtained in the
passband our most reliable values for the orbital inclination and the orientation of the orbit on the sky
, with 1 confidence intervals. The
direction of the binary system rotation on the plane of the sky is clockwise
- β¦