UX Ori Variables in the Cluster IC 348     

O. Yu. Barsunova  V. P. Grinin  S. G. Sergeev  A. O. Semenov  S. Yu. Shugarov 《Astrophysics》2015,58(2):193-203

  相似文献   

Photometric activity of UX Ori stars and related objects in the near infrared and visual. BF Ori, CQ Tau, WW Vul, and SV Cep     

V. I. Shenavrin  V. P. Grinin  A. N. Rostopchina-Shakhovskaja  T. V. Demidova  D. N. Shakhovskoi 《Astronomy Reports》2012,56(5):379-394

We have analyzed the activity of four UX Ori stars in the near-IR (JHKL) and visual (V) using the results of long-term photometric observations. For comparison, we also obtained IR (JHKLM) photometric observations of two visually quiet young stars of close spectral types (AB Aur and HD 190073). For the photometrically most active UX Ori stars BF Ori, CQ Tau, and WW Vul, the Algol-like declines of brightness in the visual, which are due to sporadic enhancements of the circumstellar extinction, are also observed (with decreasing amplitude) in the IR bands. A strict correlation between the V and J brightness variations is observed for all the stars except for SV Cep. For some of the UX Ori stars, a strong correlation between the visual and IR activity is observed up to L, where the main contribution to the emission is made by circumstellar dust. In the case of SV Cep, the visual variability is not correlated with the variability of the IR fluxes. On one occasion, a clear anti-correlation was even observed: a shallow, but prolonged decrease of the visual brightness was accompanied by an increase in the IR fluxes. This indicates that circumstellar clouds themselves can become powerful sources of IR emission. Our results provide evidence that the photometric activity of UX Ori stars is a consequence of instability of the deepest layers of their gas-dust accretion disks. In some cases (SV Cep), fluctuations of the density in this region are global, in the sense that they occur along a significant part of the circle marking the inner boundary of the dust disk. It is interesting that AB Aur, which is the quietest in the visual, appeared to be the most active in the IR. In contrast to UX Ori stars, the amplitude of its brightness variations increases from the J to the M band. It follows from analysis of the IR colors of this star that their variability cannot be described by models in which the variable IR emission has a temperature close to the sublimation temperature of silicate grains (about 1500 K). This means that the photometric activity of AB Aur must be due to both the dust and gas components of the circumstellar disk.  相似文献   

V695 Per— A Candidate AA Tau variable in the young cluster IC 348     

O. Yu. Barsunova  V. P. Grinin  S. G. Sergeev 《Astrophysics》2013,56(3):395-406

  相似文献   

Spectral observations of ɛ aurigae during the 2009–2011 eclipse     

I. S. Potravnov  V. P. Grinin 《Astronomy Reports》2013,57(12):991-1000

Results of spectral observations of the unique eclipsing binary ? Aur obtained during its recent eclipse are presented. Profile variations of many spectral lines at different eclipse phases can be traced. These variations are partly due to absorption of the stellar radiation in a rotating disk of gas and dust around the second component and partly due to geometric screening of the stellar photosphere and circumstellar region by the disk. A comparison of these results with analogous results obtained by Lambert and Sawyer during the previous (1982–1984) eclipse of ? Aur indicates good agreement, suggesting stability of the gas-dust disk surrounding the invisible component in the binary. The masses of the binary components are estimated using new observational data.  相似文献   

Detection of low-amplitude brightness oscillations in the unique eclipsing system V718 Per (HMW 15, H 187)     

V. P. Grinin  A. A. Arkharov  O. Yu. Barsunova  S. G. Sergeev 《Astronomy Letters》2009,35(12):828-835

We present new results of our visual (V, R, I) and near-infrared (J,H,K) photometry for the unusual young star V718 Per. They show that, in addition to prolonged eclipses following one another with a period of 4.7 yr, the star also exhibits low-amplitude brightness oscillations with a period that is approximately a factor of 8 shorter than the main one. In contrast to the large-scale eclipses accompanied by the star’s reddening, the low-amplitude oscillations are neutral in character and are produced by large particles. Bimodal oscillations of this type can arise in a circumstellar disk divided by a large matter-free gap into two zones—an inner, dense region and an outer, less dense disk. Such configurations emerge in the presence of a fairly massive perturbing body in the disk. In this case, density waves rotating with different angular velocities can be formed in each of these zones. Therefore, when such systems are observed nearly edge-on, two oscillation modes with different periods can be present in the extinction variations. We suggest that such a situation takes place in the case of V718 Per. Since this star exhibits no signatures of spectroscopic binarity, the perturbing body can be either a giant planet or a brown dwarf.  相似文献   

Physical conditions in emission regions and the activity mechanisms of T Tau stars     

V. P. Grinin 《Astrophysics》1980,16(2):147-155

  相似文献   

Dynamical Processes in the Neighborhood of the Herbig Ae Star MWC 480 Based on Spectral Monitoring Data     

O. V. Kozlova  V. P. Grinin  G. A. Chuntonov 《Astrophysics》2003,46(3):265-281

Spectral observations of the Herbig Ae star MWC 480 are reported. Observations were made on the 2.6 m telescope at the Crimean Astrophysical Observatory and the 6 m telescope at the Special Astrophysical Observatory in the neighborhoods of the sodium resonance doublet, the He I 5876 line, the oxygen O I 7774 line, the H line, and some others. The H line has a P Cyg-type profile which is typical of anisotropic decelerated material outflows. The parameters of the line profile vary on a time scale on the order of days or longer. The blue wing of the line profile, in which noticeable changes are detectable over times of a few hours, is subject to the greatest variation. An unusual line shape is observed in the sodium lines. Their profiles resemble type P Cyg profiles with discrete absorption components can be seen in the blue wing. The number, shape, and radial velocities of the components change with time. The maximum radial velocity is -330 km/s and the minimum, about -50 km/s. The high velocity components are subject to the greatest variability. An analysis of the spectral variability yields the following conclusions: (1) the inner layers of the accretion disk of MWC 480 reach right to the star. The maximum rotation velocity of the circumstellar gas derived from the oxygen OI 7774 line shape is close to 400-500 km/s, which corresponds roughly to the radius of the last Keplerian orbit. (2) A highly nonuniform, high velocity component of the disk wind, which contains dense fragments (microjets), develops in this region. They appear to form as a result of the unstable structure of the magnetic field in the layers of the accretion disk closest to the star. (3) The maximum velocities of the microjets are only slightly higher than the escape velocity at the star's surface. Thus, the bulk of the momentum which they acquire is expended in overcoming the star's gravity and this causes a deceleration in the radial motion of the gas. This kind of structure for the radiating region is consistent with magneto-centrifugal models of the disk wind in which the intrinsic magnetic field of the accretion disk plays a dominant role in the acceleration of the gas.  相似文献   

Theory of flare stars     

V. P. Grinin  V. V. Sobolev 《Astrophysics》1977,13(4):348-357

  相似文献   

Orientation in space of planetary nebulas     

V. P. Grinin  A. M. Zvereva 《Astrophysics》1968,4(1):43-44

  相似文献   

Unusual Eclipse of the UX Ori Type Star V719 Per     

Grinin  V. P.  Barsunova  O. Yu.  Sergeev  S. G.  Shugarov  S. Yu.  Fedorova  E. I. 《Astronomy Reports》2021,65(9):864-868

Astronomy Reports - The results of new photometric ( $$VRI$$ ) observations of the young star V719 Per from the IC 348 cluster are presented. Up until 2014, this star demonstrated brightness...  相似文献