Preface: Stars and interstellar medium

We simulate the dynamics of slender magnetic flux tubes (MFTs) in the accretion disks of T Tauri stars. The dynamical equations of our model take into account aerodynamic and turbulent drag forces, and the radiative heat exchange between the MFT and ambient gas. The structure of the disk is calculated with the help of our MHD model of the accretion disks. We consider the MFTs formed at distances of 0.027 − 0.8 au from the star with various initial radii and plasma betas β 0 . The simulations show that MFTs with a weak magnetic field (β 0 = 10) rise slowly with speeds less than the speed of sound. MFTs with β 0 = 1 form an outflowing magnetized corona above the disk. Strongly magnetized MFTs (β 0 = 0.1) can cause outflows with velocities 20 − 50 km s −1 . The tubes rise periodically over times from several days to several months according to our simulations. We propose that periodically rising MFTs can absorb stellar radiation and contribute to the IR-variability of young stellar objects.

Section: Introductionmentioning

confidence: 99%

Dynamics of magnetic flux tubes and IR-variability of young stellar objects

Khaibrakhmanov

Dudorov

Соболев

2018

“…Our conclusions are summarized in Section 6. Samus & Li (2018) noted that our attempt at automated classification seemed to be sufficiently successful. We agree with their opinion.…”

Section: Introductionmentioning

confidence: 92%

New variable stars from the photographic archive: semi-automated discoveries, attempts at automatic classification and the new field 104 Her

Antipin

Becker

Belinski

et al. 2018

Self Cite

Using 172 plates taken with the 40-cm astrograph of the Sternberg Astronomical Institute (Lomonosov Moscow University) in 1976-1994 and digitized with the resolution of 2400 dpi, we discovered and studied 275 new variable stars. We present the list of our new variables with all necessary information concerning their brightness variations. As in our earlier studies, the new discoveries show a rather large number of high-amplitude Delta Scuti variables, predicting that many stars of this type remain not detected in the whole sky. We also performed automated classification of the newly discovered variable stars based on the Random Forest algorithm. The results of the automated classification were compared to traditional classification and showed that automated classification was possible even with noisy photographic data. However, further improvement of automated techniques is needed, which is especially important having in mind the very large numbers of new discoveries expected from all-sky surveys.

“…The ground-space radio interferometer RadioAstron has a sufficient angular resolution to resolve scattered discs of some pulsars, which allows us to study the distribution of scattering matter in detail (Gwinn et al 2016;Popov et al 2016Popov et al , 2017Shishov et al 2017;Andrianov et al 2017). The summary of main RadioAstron results was introduced in the All-Russian Astronomical Conference VAK-2017 that was held on 2017 September 17 (Samus & Li 2018).…”

Section: Introductionmentioning

confidence: 99%

Uncertainty in measurements of the distances of scattering screens in pulsar observations

Fadeev

2018

In our previous paper we investigated properties of the ionized interstellar medium in the direction of three distant pulsars: B1641-45, B1749-28 and B1933+16.We found that uniformly distributed scattering material cannot explain measured temporal and angular broadening. We applied a model for a thin scattering screen and found the distances to the scattering screens in all directions. In this paper, we consider more complicated models of scattering material distribution, such as models containing both a uniformly distributed medium and thin screen. Based on these models, we estimate the accuracy of localization of scattering screens and the possible relative contribution of each scattering component.