1,283 research outputs found
Main results of the experiments conducted during the flight of the Kosmos-1129 Biosatellite and the status of preparation of studies on the next biosatllite
Experiments included studies on the biological effects of weightlessness. Space flight stress, disorientation, and physiological factors are discussed for each experimental subject. The subjects included rats, drosophila flies, and plants. Metabolic rates were monitored along with other changes in the subject's activity cycles
Flares in Open Clusters with K2. I. M45 (Pleiades), M44 (Praesepe) and M67
The presence and strength of a stellar magnetic field and activity is rooted
in a star's fundamental parameters such as mass and age. Can flares serve as an
accurate stellar "clock"?
To explore if we can quantify an activity-age relation in the form of a
flaring-age relation, we measured trends in the flaring rates and energies for
stars with different masses and ages.
We investigated the time-domain photometry provided by Kepler's follow-up
mission K2 and searched for flares in three solar metallicity open clusters
with well-known ages, M45 (0.125 Gyr), M44 (0.63 Gyr), and M67 (4.3 Gyr). We
updated and employed the automated flare finding and analysis pipeline
Appaloosa, originally designed for Kepler. We introduced a synthetic flare
injection and recovery subroutine to ascribe detection and energy recovery
rates for flares in a broad energy range for each light curve. We collected a
sample of 1 761 stars, mostly late-K to mid-M dwarfs and found 751 flare
candidates with energies ranging from erg to
erg, of which 596 belong to M45, 155 to M44, and none to M67.
We find that flaring activity depends both on , and age. But
all flare frequency distributions have similar slopes with , supporting a universal flare generation process. We discuss
implications for the physical conditions under which flares occur, and how the
sample's metallicity and multiplicity affect our results.Comment: 17 pages, 11 figures, appendix. Accepted to A&
Dual models for p-form mimetic gravity and their connection to perfect fluids consisting of (p+1)-branes
We propose an approach that allows one to reformulate -dimensional
-form mimetic gravity (including usual mimetic gravity as particular case ) as nonlinear -form electrodynamics via electric-magnetic
duality. The resulting dual Lagrangian density is just the square root of the
ordinary quadratic Lagrangian density of -form electrodynamics. By
applying field transformation in the action, we show that for the arbitrary
this dual theory transforms into the -brane fluid: the model of the
stack of the parallel -branes foliating physical spacetime. As the
structure of the field transformations depends on , the sets of solutions in
these models are related differently. We prove, that for and
dual mimetic models describe usual particle fluid with the potential flow and
to the -brane fluid respectively. For other values of not all
mimetic solutions behave like that, in general, so we restrict ourselves only
to the case , . In this case, we show, that mimetic formulation
is dual to the well-known Nielsen-Olesen theory of "dual strings" and discuss
the criterion indicating whether its solutions behave like string fluid.Comment: 12 page
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