The BM Ori System. III. The Depth of the Minimum in the Infrared

The depth of the minimum of the BM Ori eclipsing system is studied in the infrared. For this purpose, observations have been made in the JHKLM bands outside the eclipse and in the JHKL bands near the central phase of the eclipse. The depth of the minimum is found to have a complicated wavelength dependence. In the short wavelength region of the spectrum this depth decreases from the U band to the R band (λ=0.36–0.71 mm), which is explained in terms of eclipsing of the principal star by a dust cloud surrounding the companion and by the disk of the companion. In the IR the depth of the minimum increases sharply from the I to the L band (λ=0.97–3.5 mm). This effect can be explained by partial obscuring of the hot region of the dust cloud by the disk of the companion. __________ Translated from Astrofizika, Vol. 48, No. 4, pp. 565–573 (November 2005).     

Spectroscopic Observations of Subfuors (Exors). I. V1118 Ori

Spectroscopic observations of the star V1118 Ori during the 1992-94 outburst showed that, as during the 1989 outburst, the spectrum resembles that of a T Tauri star with strong hydrogen and Ca II lines, as well as Fe I, Fe II, He I, and Na I lines of moderate intensity.     

The system Bm Ori. V. Improved photometric elements

The times of individual minima taken from the literature are used to plot the dependence of O-C on revolution number for the eclipsing star BM Ori. A least squares fit of this plot yields the following photometric elements: Min I=JD2440265.331(5)+6.470524(3)·E. __________ Translated from Astrofizika, Vol. 51, No. 3, pp. 501–503 (August 2008).     

The Herbig Ae/Be Star V586 Ori

Studies of the Herbig Ae/Be star V586 Ori based on photoelectric observations in the Strömgren system are reported. It is found that as the brightness decreases, the Balmer discontinuity index initially increases and then begins to drop. As the star fades, the index decreases. We have previously found similar variations in the indices and C for UX Ori, RR Tau, and V351 Ori. It is shown that V586 Ori has the characteristics of a shell-star.     

Spectral Observations of Subfuors (Exors). II. V1143 Ori

Spectral observations of the subfuor (exor) V 1143 Ori during the outburst of 1992-93 are reported. Data on the behavior of the Ca II infrared triplet before and during the outburst are presented for the first time. The amplitudes of the outbursts during 1982-94 show that their maxima do not vary greatly on the average. Between outbursts, when the star is in the minimum of its active period, the spectrum of V 1143 Ori is typical of a WTTS and during an outburst, of a CTTS.     

Velocity Distribution of Stars in the Pup-CMa Association

The distribution of proper motions of stars in the Pup-CMa association is presented. The stars' velocities are approximately parallel to each other, which indicates that the stars are close together in space. The mutual distribution of stars and molecular clouds in the association is interpreted as proof that the stars emerged from a single gigantic primordial molecular cloud (or several large clouds), destroyed by radiation and/or stellar wind coming from those stars. It is assumed that part of that cloud is being dissipated, while part is being broken into several small clouds, which we are observing at present.     

Spectral and photometric observations of the star Y Ori

Data are presented from a spectral and photometric study of the long-period variable star Y Ori, which we have classified as a type M7IIIe near its brightness minimum. In the blue part of the spectrum, features from a star of an earlier spectral class are superimposed on the spectrum of a cool giant, so that a variable excess emission is observed at wavelengths of 4000–4200 Å. As opposed to the monotonically decreasing intensity of the Balmer lines (EWHα > EWHβ > EWHγ > EWHδ) in normal stars belonging to the earlier spectral classes, a reverse relationship, with EWHγ < EWHδ is detected in Y Ori. Translated from Astrofizika, Vol. 51, No. 4, pp. 567–575 (November 2008).     

Large-scale photometric activity of UX Ori type stars

Radical readjustments in the photometric activity of young stars owing to sudden changes in the circumstellar extinction are discussed using the light curves of two UX Ori type stars, CQ Tau and V1184 Tau, as examples. Changes of this sort can be caused by large deviations from axial symmetry in the distribution of circumstellar dust, as well as by large variations in the mass accretion rate in circumstellar disks. A large amount of dust may also appear in the vicinity of a young star owing to collisions of planetesimals. __________ Translated from Astrofizika, Vol. 51, No. 1, pp. 5–13 (February 2008).     

The spectroscopic orbit of the short period eclipsing binary V 836 Cygni

Spectroscopic elements of the single-lined spectroscopic binary V 836 Cyg are presented.     

Astrophysical supplements to the ASCC‐2.5. I. Radial velocity data

We present a catalogue of radial velocities of Galactic stars with high precision astrometric data CRVAD which is the result of the cross‐identification of star lists from the General Catalog of Average Radial Velocities (GCRV) and from the homogeneous All‐sky Compiled Catalogue of 2.5Million Stars (ASCC‐2.5). The CRVAD includes accurate J2000 equatorial coordinates, proper motions and trigonometric parallaxes in the Hipparcos system, Johnson's BV photometric data, spectral types, multiplicity and variability flags from the ASCC‐2.5, and radial velocities, stellar magnitudes and spectral types from the GCRV for 34553 ASCC‐2.5 stars. The CRVAD was used for the construction of a sample of standard stars with accurate astrometric, photometric and radial velocity data for the RAVE project. A second application of the CRVAD , the radial velocity determination for 292 open clusters (including 97 with previously unknown radial velocities), using their newly defined members from proper motions and photometry in the ASCC‐2.5, is briefly described. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The eccentric double-lined binary BD — 1° 1004

A new radial velocity study has been made of the highly eccentric, early-type binary BD -1° 1004 using spectra from the Kavalur Observatory. All available archival material has also been reexamined. An attempt has been made to correct for line ‘dragging’ by the secondary spectrum to improve the fit of the observed data to the orbital solutions. It is found that an earlier suggestion of apsidal regression is still possible although ω is probably constant within the errors. There remain problems and inconsistencies with other orbital elements, in particular K₁ and γ     

Photometric activity of the UX Ori star V1184 Tau in the optical and near-infrared spectral ranges

We present the results of our infrared JHK photometry for the unusual UX Ori star V1184 Tau. Comparison with previous observations performed before the catastrophic decline in its optical brightness in 2004 (when the star faded approximately by a factor of 100) has shown the following: the star faded approximately by 2 ^m and 1 ^m in the J and H bands, respectively, while its K brightness remained almost constant. This pattern of infrared variability seems incompatible with the mechanism of variable circumstellar extinction responsible for the dramatic decline in the star’s optical brightness. However, if this mechanism is considered in the context of an accretion disk model with a puffed-up inner rim in the dust sublimation zone and with a disk wind producing an expanding gas-dust atmosphere above the disk surface, then the paradox can be resolved. In this model, the photometric activity of V1184 Tau in both visible and near-infrared spectral ranges, including the sharp brightness decline in 2004, can be explained by an increase in the geometric thickness of the disk in the dust sublimation zone caused by enhanced accretion of circumstellar matter onto the star. There is reason to believe that such events occur periodically and result from the presence of a companion to V1184 Tau moving in a highly eccentric orbit. The offered interpretation of the photometric activity of V1184 Tau allows this object to be classified as an UX Ori star based on the observed photometric effect and, at the same time, as a FU Ori star based on the pattern of the physical process that produced this effect.     

The BM Ori System. II. Abundances of Helium and Iron in the Atmosphere of the Primary Star

The abundances of helium and iron in the atmosphere of the principal star of the BM Ori system are estimated. Spectra obtained with the BTA telescope and from the archives of the IUE and HST satellites are used. It turns out that the helium abundance is close to that in the sun, while that of iron is lower. The helium and iron abundances in other stars of the Trapezium of Orion are generally similar to those in BM Ori, but there are some differences. For example, of the two stars ¹ Ori C and ¹Ori D, one has a higher and the other a lower abundance of helium than does the sun. At the same time, the secondary of BM Ori has a normal abundance of iron.     

Spectroscopic binaries near the North Galactic pole

Photoelectric radial-velocity measurements show that 6 Boötis undergoes small periodic variations of velocity. An orbit with a 2.6-year period and a semi-amplitude of little more than 1 km s^-1 is derived. The amplitude is smaller by a factor of two than that of any plausible orbit previously derived from radial velocities.     

Spectroscopic binaries near the north galactic pole

Photoelectric radial-velocity measurements show that HD 105982 is a spectroscopic binary with a period of 3.7 years.     

Spectroscopic binaries near the north galactic pole

Photoelectric radial-velocity measurements show that HD 105341 is a spectroscopic binary with a near-circular orbit and a period of 194 days.     

Spectroscopic binaries near the north galactic pole

Photoelectric radial-velocity measurements show that the tenth-magnitude object HD 110195 is a double-lined spectroscopic binary. It consists of two very similar late-G dwarfs in an orbit having high eccentricity and a period of 18 days.     

Spectroscopic binaries near the north Galactic pole paper 8: HD 121844

Photoelectric radial-velocity measurements show that HD 121844 is a spectroscopic binary with a period of 303 days, a high eccentricity (0.49) and a high negative γ-velocity (- 61 km s^-1).     

Measurement of the longitudinal magnetic-field component for FU Ori

The Main Stellar Spectrograph of the 6-m Special Astrophysical Observatory telescope equipped with a polarimetric analyzer was used to measure the longitudinal magnetic-field component of FU Ori on January 24, 2002. The following (3σ) upper limits were obtained for the magnetic field B_‖: B_‖<350–400 G in the formation region of Fe I, Ni I, and Ca I absorption lines (disk + wind), and B_‖<200 G in the formation region of the absorption component of the Hα line with a P Cyg profile. We conclude that the strength of a large-scale magnetic field capable of collimating the disk wind does not exceed 300 G. For the region where the emission component of the Hα line is formed, we found that B_‖<100 G. Such a low value may have been obtained because the magnetic field lines in this region were almost perpendicular to the line of sight at the time of our observations.