ABSTRACT
BP Psc is an active late-type (sp:G9) star with unclear evolutionary status lying at high-galactic latitude b = −57°. It is also the source of the well collimated bipolar jet. We present ...results of the proper motion and radial velocity study of BP Psc outflow based on the archival Hα imaging with the GMOS camera at 8.1-m Gemini-North telescope as well as recent imaging and long-slit spectroscopy with the SCORPIO multimode focal reducer at 6-m BTA telescope of SAO RAS. The 3D kinematics of the jet revealed the full spatial velocity up to ∼140 km s−1 and allows us to estimate the distance to BP Psc system as D = 135 ± 40 pc. This distance leads to an estimation of the central source luminosity L* ≈ 1.2 L⊙, indicating that it is the ≈1.3M⊙ T Tauri star with an age t ≲ 7 Myrs. We measured the electron density of order Ne ∼ 102 cm−3 and mean ionization fraction f ≈ 0.04 within the jet knots and estimated upper limit of the mass-loss rate in NE lobe as $\dot{M}_{\rm out}\approx 1.2\cdot 10^{-8}{\rm M}_{\odot }\,{\rm yr}^{-1}$. The physical characteristics of the outflow are typical for the low-excitation YSO jets and consistent with the magnetocentrifugal mechanism of its launching and collimation. Prominent wiggling pattern revealed in Hα images allowed us to suppose the existence of a secondary substellar companion in a non-coplanar orbit and estimate its most plausible mass as Mp ≈ 30MJup. We conclude that BP Psc is one of the closest to the Sun young jet-driving systems and its origin is possibly related to the episode of star formation triggered by expanding supershells in second Galactic quadrant.
The star CQ Tau belongs to the family of UX Ori type stars and is characterized by very complicated photometric behavior and a complex structure of its circumstellar environment. Based on published ...photometric data, in this article we construct a light curve for this star covering 125 years. It implies that besides a random component characteristic of UX Ori type stars, the changes in brightness also include a large amplitude periodic component with a period of 10 years. It existence was suspected previously and new observations confirm its reality. This indicates the existence of a second component in the neighborhood of the star. Matter flows and density waves caused by the motion of the companion lead to periodic changes in the circumstellar extinction and brightness of the star. This result is discussed in the context of recent observations of CQ Tau with high angular resolution.
The star RZ Psc is one of the most unusual members of the UX Ori star family. It demonstrates all properties that are typical of these stars (the light variability, high linear polarization in deep ...minima, the blueing effect), but until recently there has been no obvious evidence of its youth. Recently, we have shown that RZ Psc is in the transitional evolutionary stage between stars with the primordial and debris disks. In this paper we present the results of the quantitative analysis of the star’s spectrum. Using the high-resolution (R = 46 000) spectrum of RZ Psc obtained with Nordic Optical Telescope, we determined Teff = 5350 ± 150 K, log g = 4.2 ± 0.2, M/H = −0.3 ± 0.05. These parameters agree well with the same ones as for the stars recently passed the T Tauri star evolutionary stage. This supports our previous suggestion about the evolutionary status of RZ Psc as the post-T Tauri and post-UX Ori star.
RZPsc is an isolated high-latitude post-T Tauri star that demonstrates a UX Ori-type photometric activity. The star shows very weak spectroscopic signatures of accretion, but at the same time ...possesses the unusual footprints of the wind in NaiDlines. In the present work we investigate new spectroscopic observations of RZPsc obtained in 2014 during two observation runs. We found variable blueshifted absorption components (BACs) in lines of the other alcali metals, Ki 7699 A and Caii IR triplet. We also confirmed the presence of a weak emission component in the H alpha line, which allowed us to estimate the mass accretion rate on the star as M< or = 7 x 10 super(-12)M sub(middo t in circle)yr super(-1). We could not reveal any clear periodicity in the appearance of BACs in sodium lines. Nevertheless, the exact coincidence of the structure and velocities of the Nai D absorptions observed with the interval of about one year suggests that such a periodicity should exist.
RZ Psc is an isolated high-latitude post-T Tauri star that demonstrates a UX Ori-type photometric activity. The star shows very weak spectroscopic signatures of accretion, but at the same time ...possesses the unusual footprints of the wind in Na i D lines. In the present work we investigate new spectroscopic observations of RZ Psc obtained in 2014 during two observation runs. We found variable blueshifted absorption components (BACs) in lines of the other alcali metals, K i 7699 Å and Ca ii IR triplet. We also confirmed the presence of a weak emission component in the Hα line, which allowed us to estimate the mass accretion rate on the star as Ṁ ≤ 7 × 10-12M⊙ yr-1. We could not reveal any clear periodicity in the appearance of BACs in sodium lines. Nevertheless, the exact coincidence of the structure and velocities of the Na i D absorptions observed with the interval of about one year suggests that such a periodicity should exist.
Polarimetry of the Nova V339 Del Shakhovskoy, D. N.; Antonyuk, K. A.; Belan, S. P.
Astrophysics,
03/2017, Letnik:
60, Številka:
1
Journal Article
Recenzirano
Polarimetric UBVRI observations of the Nova V339 Del during the 5-108 days following the maximum of the outburst of 2013 reveal a variability in the degree of linear polarization with an amplitude of ...about 0.2%. The character of the variability in the polarization parameters during the period up to 30 days after the maximum is indicative of a nonspherical diffuse shell, with a geometry that is more likely bipolar than disk-shaped. In the early nebular stage (30-100 days after the maximum) a variability in the position angle of the intrinsic polarization was observed that suggests that the shape of the shell deviates from axial symmetry.
We report measurements of linear and circular polarization for the recent comet C/2009 P1 (Garradd) during its approach to the Earth in 2011–2012. Aperture photoelectric observations were carried out ...on July 29, 2011-April 22, 2012 in the R and WR wide-band filters at the 2.6-m telescope of the Crimean Astrophysical Observatory (Ukraine). Spectropolarimetric measurements of linear polarization in the range 3800–8000 Å and imaging circular polarimetry in the comet continuum filter (
λ
0
= 6840/90 Å) were also carried out with the SCORPIO-2 focal reducer at the 6-m telescope of the Special Astrophysical Observatory (Russia) on February 2-April 21, 2012. The degree of polarization of light scattered by comet Garradd changes from −2.2 ± 0.2% to 4.9 ± 0.2% at phase angles 13.7° and 35.9°, respectively. These values are in a good agreement with those for dusty comets at the respective phase angles. Left-handed (negative) circular polarization of comet Garradd in the continuum filter was identified. The values of Pc vary noticeably over the coma in the range from −0.03 to −0.08% and from −0.05 to −0.3% on February 14 and April 21, respectively. These results confirm our previous conclusion that the observed circular polarization for comets is predominantly left-handed.
We present results of a multisite photometric campaign on the high-amplitude δ Scuti star KIC 6382916 in the Kepler field. The star was observed over a 85-d interval at five different sites in North ...America and Europe during 2011. Kepler photometry and ground-based multicolour light curves of KIC 6382916 are used to investigate the pulsational content and to identify the principal modes. High-dispersion spectroscopy was also obtained in order to derive the stellar parameters and projected rotational velocity. From an analysis of the Kepler time series, three independent frequencies and a few hundred combination frequencies are found. The light curve is dominated by two modes with frequencies f
1 = 4.9107 and f
2 = 6.4314 d−1. The third mode with f
3 = 8.0350 d−1 has a much lower amplitude. We attempt mode identification by examining the amplitude ratios and phase differences in different wavebands from multicolour photometry and comparing them to calculations for different spherical harmonic degree, l. We find that the theoretical models for f
1 and f
2 are in a best agreement with the observations and lead to value of l = 1 modes, but the mode identification of f
3 is uncertain due to its low amplitude. Non-adiabatic pulsation models show that frequencies below 6 d−1 are stable, which means that the low frequency of f
1 cannot be reproduced. This is a further confirmation that current models predict a narrower pulsation frequency range than actually observed.
We present in this paper several high resolution ($R = 27 000$) spectra of five UXORs (UX Ori, CQ Tau, BF Ori, RR Tau, WW Vul), which cover the entire visual range, from 3900 to about 8700 Å. There ...are between 4 and 7 spectra per star, obtained over a time interval of two years. Simultaneous or quasi-simultaneous photometric observations were also obtained at the Crimean Astrophysical Observatory. The complete, reduced and normalized spectra are available in electronic form. We show for each star a selection of the most interesting lines, and the full spectrum of UX Ori computed by averaging the spectra obtained when the star was at maximum light. For UX Ori we show also the synthetic spectrum and provide an identification of most of the lines. The spectra are too sparse to form true time sequences; however, they provide an extremely useful database for studies of UX Ori-type stars. We discuss briefly the main features of the spectra. We show that they contain many time-stable photospheric lines that can be described to a good approximation by the synthetic spectra of normal A stars with $\log g$ $ = 3.5 {-} 4$ and we derive for each star effective temperature, gravity and rotational velocity. We examine the time variability of selected lines and study their connection with the photometric activity of the stars. Two different types of spectral variability are identified. One is common to all stars with circumstellar (CS) gas and is caused by perturbations of the physical and kinematic conditions of the emitting region. There is no correlation between this type of activity and the brightness variations of the star. On the contrary, a second type of spectral variability correlates well with the brightness variations and is very likely connected with the screening effect of an opaque dust cloud which sporadically intersects the line of sight. This type of variability has been observed in its simplest form in one of the RR Tau spectra, where the equivalent width of the forbidden line Oi 6364 Å increased by a factor of about three as the star faded by approximately the same amount.
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