Dusty Clusters Research Articles

Iron sulfides in sediments of glacial lakes of the upper Kolyma region

Iron sulfides are common in the sediments of glacier lakes of the Magadan region -Gryazevoe (61°08’21” N, 152°19’57” E), Nalimnoe (61°07’41” N, 152°20’8” E), Sosednee (62°03’29” N, 149°3122” E), Sapog (63°29’9” N, 147°50’41” E), Vodorazdel’noe (63°44’8” N, 148°13’4” E), Ui (63°49’31” N, 147°53’21” E) and others. Most of the lakes were formed at the end of the Late Pleistocene or at the beginning of the Early Holocene. Sulfides occur in the spheroid forms with a framboidal structure, dusty clusters, and individual crystals. Sometimes sulfides fill up the diatom valves. The size of framboids does not exceed 100 µm. Sulfides have pyrite, greigite and pyrrhotite compositions. They are distributed unevenly in sections. Greigite and pyrrhotite are distinguished by their magnetic characteristics.

Dust-buried Compact Sources in the Dwarf Galaxy NGC 4449

Multiwavelength images from the Hubble Space Telescope covering the wavelength range 0.27–1.6 μm show that the central area of the nearby dwarf galaxy NGC 4449 contains several tens of compact sources that are emitting in the hydrogen recombination line Paβ (1.2818 μm) but are only marginally detected in Hα (0.6563 μm) and undetected at wavelengths λ ≤ 0.55 μm. An analysis of the spectral energy distributions (SEDs) of these sources indicates that they are likely relatively young stellar clusters heavily attenuated by dust. The selection function used to identify the sources prevents meaningful statistical analyses of their age, mass, and dust extinction distributions. However, these cluster candidates have ages ∼5–6 Myr and A V > 6 mag, according to their SED fits, and are extremely compact, with typical deconvolved radii of 1 pc. The dusty clusters are located at the periphery of the dark clouds within the galaxy and appear to be partially embedded. Density and pressure considerations indicate that the H ii regions surrounding these clusters may be stalled, and that pre-supernova (pre-SN) feedback has not been able to clear the clusters of their natal cocoons. These findings are in potential tension with existing models that regulate star formation with pre-SN feedback, since pre-SN feedback acts on short timescales, ≲4 Myr, for a standard stellar initial mass function. The existence of a population of dusty stellar clusters with ages >4 Myr, if confirmed by future observations, paints a more complex picture for the role of stellar feedback in controlling star formation.

Formation of the structures from dusty clusters in neon dc discharge under cooling

The formation of structures consisted of dusty clusters in plasma at the discharge tube cooling to a temperature of liquid nitrogen was discovered. The dependence of the reduced electric field in the positive column of a discharge on gas temperature was experimentally measured. Depending on the pressure of neon were observed the different structural transitions in the regions of growing current-voltage characteristics at low discharge currents ≤ 1 mA. It was found that the regions of existence of structured clusters and the regions of structural transitions were characterized by the higher values of the reduced electric field than the regions of destruction of ordered structures.

Increase of Kinetic Energy of Dusty Cluster Particles Due to Parametric Instability Caused by Nanosecond Electric Pulses

AbstractExperimental investigations of high voltage nanosecond pulses influence on charged dust particles in low pressure rf–plasma were carried out. Application of repetitive pulses leads to the vertical oscillations of the mi‐croparticles. Evolution of the total kinetic energy for the cluster consisting of 14 particles is investigated. Flat clusters exhibit parametric instabilities of horizontal modes. In the initial phase the kinetic energy oscillates around a certain value and its amplitude grows very slowly. At a certain moment during the instability it goes into the exponential growth phase and then saturates under the effect of repetitive pulses. It is possible if the eigenfrequency is the function of height and the dust particle oscillates vertically in the non uniform electric field (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

A Near-Infrared Survey of the N49 Region around the Soft Gamma Repeater SGR 0526-66

We report the results of a deep near-infrared survey with the Very Large Telescope/Infrared Spectrometer and Array Camera of the environment of the supernova remnant N49 in the Large Magellanic Cloud, which contains the soft gamma repeater SGR 0526-66. Two of the four confirmed SGRs are potentially associated with compact stellar clusters. We thus searched for a similar association of SGR 0526-66 and imaged a young stellar cluster at a projected distance of ~30 pc from the SGR. This constitutes the third cluster-SGR link and lends support to scenarios in which SGR progenitors originate in young dusty clusters. If confirmed, the cluster-SGR association constrains the age and thus the initial mass of SGR progenitors.

Noise driven configuration of dust clusters by molecular dynamics simulation

Molecular dynamics simulations are employed to study the effect of noise on the stationary configuration formation of clusters of two-dimensional dusty plasma. It is found that the noise can induce a new stable cluster configuration that is significantly different from that without noise. And, the tunneling crisis phenomena of nonlinear dynamical system is also exhibited in few body dusty clusters studied under noise. Some implication of results to experiments is also discussed.

Spectral properties of small dusty clusters.

A monolayer dusty crystal can be observed in the glow discharge. In particular, a small number of dusty grains form simple atom-like plane clusters. Stability and oscillations of the polygonal cluster are considered. For the simplest stable clusters normal displacements and frequencies are found for an arbitrary form of mutual interaction. The measurement of these modes can help to give in detail the form of the potential function.