Speckle Interferometry with CMOS Detector Strakhov, I. A.; Safonov, B. S.; Cheryasov, D. V.
Astrophysical bulletin,
06/2023, Letnik:
78, Številka:
2
Journal Article
Recenzirano
In 2022 we carried out an upgrade of the speckle polarimeter (SPP)—the facility instrument of the 2.5-m telescope of the Caucasian Observatory of the SAI MSU. During the overhaul, CMOS Hamamatsu ...ORCA-Quest qCMOS C15550-20UP was installed as the main detector, some drawbacks of the previous version of the instrument were eliminated. In this paper, we present a description of the instrument, as well as study some features of the CMOS detector and ways to take them into account in speckle interferometric processing. Quantitative comparison of CMOS and EMCCD in the context of speckle interferometry is performed using numerical simulation of the detection process. Speckle interferometric observations of 25 young variable stars are given as an example of astronomical result. It was found that BM And is a binary system with a separation of 273 mas. The variability of the system is dominated by the brightness variations of the main component. A binary system was also found in NSV 16694 (TYC 120-876-1). The separation of this system is 202 mas.
Despite the thousands of planets in orbit around stars known to date, the mechanisms of planetary formation, migration, and atmospheric loss remain unresolved. In this work, we confirm the planetary ...nature of a young Saturn-size planet transiting a solar-type star every 8.03 d, TOI-1135 b. The age of the parent star is estimated to be in the interval of 125-1000 Myr based on various activity and age indicators, including its stellar rotation period of 5.13 ± 0.27 days and the intensity of photospheric lithium. We obtained follow-up photometry and spectroscopy, including precise radial velocity measurements using the CARMENES spectrograph, which together with the TESS data allowed us to fully characterise the parent star and its planet. As expected for its youth, the star is rather active and shows strong photometric and spectroscopic variability correlating with its rotation period. We modelled the stellar variability using Gaussian process regression. We measured the planetary radius at 9.02 ± 0.23 R ⊕ (0.81 ± 0.02 R Jup ) and determined a 3 σ upper limit of < 51.4 M ⊕ (< 0.16 M Jup ) on the planetary mass by adopting a circular orbit. Our results indicate that TOI-1135 b is an inflated planet less massive than Saturn or Jupiter but with a similar radius, which could be in the process of losing its atmosphere by photoevaporation. This new young planet occupies a region of the mass-radius diagram where older planets are scarse, and it could be very helpful to understanding the lower frequency of planets with sizes between Neptune and Saturn.
In recent years, there has been a growing interest in the contribution of neuroretinal degeneration to the pathogenesis of diabetic retinopathy (DR).
This study assesses the effect of the drug ...Retinalamin on the functional state of the retina in patients with DR using the Diopsys NOVA Vision Testing System that utilizes electrophysiological (EP) technology.
The study included patients with type 1 and 2 diabetes mellitus (DM) with DR of any stage without macular edema. Patients underwent standard ophthalmological examination and objective functional examination of the retina using the Diopsys NOVA Vision Testing System. The control group consisted of patients with type 1 and 2 DM with DR who did not receive Retinalamin.
Significant changes in pattern electroretinography and flash electroretinography parameters were recorded in patients who received a course of Retinalamin. Two clinical examples are presented, which can be designated as the first experience of objective functional monitoring of treatment of patients with DR with Retinalamin.
Retinoprotective therapy is necessary already at the early stages of DR. Electroretinography is an objective tool for functional analysis of the earliest changes in retinal cells in DR. It is necessary to use the identified "therapeutic" window for the appointment of retinoprotective agents.
Appropriate use of Kazakhstan’s nonclinkering coal is of great interest. Information is presented regarding the content of nonferrous and rare metals in coal from different parts of the world, ...including Kazakhstan and the Kuznetsk Basin. The prospects for extracting valuable metals from coal and, in particular, coal ash are explored. In the first stage, the content of nonferrous and rare metals in Kazakh lignite and long-flame coal is assessed. The Kumyskuduk, Karazhyra, and Shubarkol fields are most promising. High concentrations of valuable metals in nonclinkering coal may be associated with external sources and with the high sorptional capacity of the coal. For some metals—barium, cadmium, niobium, strontium, tantalum, and zirconium—the content almost matches that in commercial ores. The content of rare and rare-earth metals in Kazakhstan’s nonclinkering coal and ash tailings demands further assessment. Economic analysis of metal extraction from coal and its ash is also required, so as to select the optimal technology.
The results of photometric and spectral observations of T CrB obtained in a wide range of wavelengths in 2011–2023 are presented. We use the near-IR light curves to determine a new ephemeris
for the ...times of light minima when the red giant is located between the observer and the hot component. The flux ratio H
/H
varied from
to
in 2020–2023, which may be due to a change in the flux ratio between the X-ray and optical ranges. It is shown that the value of H
/H
anticorrelates with the rate of accretion onto the hot component of the system. Based on high-speed follow-up observations obtained on June 8, 2023, we detected a variability of the He II
line with a characteristic time-scale of
min, the amplitude of variability in the
-band was
. Simulations of the near-IR light curves accounting for the ellipsoidal effect allowed us to obtain the parameters of the binary system: the Roche lobe filling factor of the cool component
, the mass ratio
, the orbital inclination
. A comparison of the light curve obtained in 2005–2023 with the 1946 outburst template made it possible to predict the date of the upcoming outburst—January 2024.
The results of photometric, polarimetric, and spectroscopic observations of the young star ZZ Tau IRS in the visible and near-infrared bands are presented. Against the continuum of an M spectral type ...star about 50 emission lines of allowed (H I, He I, Na I, S II) and forbidden (O I, O II, O III, N I, N II, S II, Ca II, Fe II, Ni II) transitions were identified. It was found that from the autumn of 2020 to the beginning of 2023, the brightness of the star in the visible region decreased
) and then began to return to the initial level. As the visible brightness of the star declined, its color indices decreased in the visible region, but increased in the near-IR bands. At light minimum, the degree of polarization in the
band reached approx 13
, and the equivalent widths of, e.g., the H
and S II
6731 lines increased to 376 and 79
, respectively. Arguments are given in favor of ZZ Tau IRS being a UX Ori type star, and its variability being due to eclipses by dust clouds, which are inhomogeneities in the dusty disk wind. Forbidden lines are formed both in the disk wind and in the jet, the axis of what is oriented along
. The jet mass-loss rate exceeds
yr
, what is abnormally large for a star with a mass less than
. Apparently, the disk wind of ZZ Tau IRS is not axially symmetric, probably due to the azimuthal asymmetry of the protoplanetary disk found earlier from ALMA observations.
The morphology and kinematics of the matter in the vicinity of young stars ZZ Tau and ZZ Tau IRS are studied. It has been found that the emission nebula (the H
filament) located southwest of these ...stars, as well as the Herbig–Haro object HH 393 projected onto it are moving away from ZZ Tau and ZZ Tau IRS with a radial velocity of about 50 km s
. On the inner edge of the western part of the H
filament, there is a cooler filament emiting in the molecular hydrogen line (
m) and in the dust continuum. In the northeastern part of the studied region, a new Herbig–Haro object is discovered and assigned the number HH 1232. The presence of several more new emission nebulae is suspected. The electron density in the studied regions of the H
filament, as well as HH 393 and HH 1232
cm
. Arguments are presented in favor of the fact that the dusty disk wind has created a gas-and-dust nebula around ZZ Tau IRS, along the symmetry axis of which there is a jet moving in the direction of HH 393.
Mathematical and computer models of the behavior of thermal protection systems composed of highly extended elastomers are formulated based on the analysis and generalization of the results of ...theoretical and experimental research. The results of numerical studies show satisfactory agreement with the experimental data.
Glaucoma is a disease associated with increased intraocular pressure (IOP). Of the pharmacological agents for treating glaucoma, there are drugs of the first (most effective and safe) and second-line ...treatment. First-line treatment includes prostaglandin analogs and beta-blockers. The currently used prostaglandin analogs (latanoprost, bimatoprost, tafluprost and travoprost) are PG F2α analogs that act through stimulation of FP receptors. They are distinguished by the optimal ratio of effectiveness and risk of side effects. They are convenient for the patient because for the therapeutic effect, it is enough to prescribe 1 time per day. As a result, it is rational to start the treatment of glaucoma with a drug in this group. In terms of pharmacoeconomics, the most affordable prostaglandin drug is latanoprost, which is generally as effective as other prostaglandin analogs. β-adrenergic blockers reduce the production of intraocular fluid, the formation of which is controlled by β1- and β2-adrenergic receptors. Therefore, non-selective β-blockers (timolol, levobunolol, metipranolol, and carteolol) have a pharmacodynamic advantage over selective β1-adrenergic antagonists (betaxolol). Conducted clinical studies of β-blockers have shown that given the cost, efficacy and safety, timolol was the most preferable treatment for glaucoma. In the presence of medical contraindications to the use of first-line drugs or to enhance their effectiveness, α2-agonists (apraclonidine and brimonidine), carbonic anhydrase inhibitors (usually local action: dorzolamide and brinzolamide), M-cholinomimetics (pilocarpine, carbachol and echothiopate), and also Rho-kinase inhibitors (ripasudil)
The replacement of graphite by petroleum coke in lubricants for railroad lines is considered. The lubricant consists of petroleum coke, spent diesel oil, and low-molecular polyethylene. On mixing, ...these components form a system that is stable on storage. The particle size of the petroleum coke is selected so as to minimize wear of the metal. The hydrocarbons employed are biodegradable; that minimizes their environmental impact. The proposed lubricant has been successfully used by the East Siberian Railroad on curved track and at switches. It is easy to apply, does not drip, and is transferred by the wheels of rail cars to ensure uniform distribution over the rail’s lateral surface.
