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—We present the study of the multiple system HD 52721 by means of speckle interferometry in 2019–2020 at the 6-m telescope of the SAO RAS. Formerly, HD 52721 was known as triple ( $$6.93$$ (B2V + B2V; $$P = {{1}^{{\text{d}}}}.6101570$$ ) + $$7.88$$ ; $$0_{.}^{'}65$$ ). In our work, the system is resolved as a speckle interferometric triple system, i.e., the total system multiplicity increased up to four components ( $$6.80$$ (B2Ve; $${{1}^{{\text{d}}}}.6101570$$ )+ $$8.95$$ (B9VХ, $$0_{.}^{{''}}03$$ ); $$0_{.}^{{''}}64$$ ). We have used the reference-dependent and reference-independent methods for measuring positional parameters and magnitude differences between the components. The obtained measurements of the brightness differences agree with the observed light curve of the eclipsing pair.

This paper is a continuation of our earlier work devoted to determining the orbit and mass of the star 61 Cyg and the changes in the photometric characteristics of its components. The purpose of this work has been to refine the orbital elements, estimate the masses, and search for possible manifestations of periodic components in deviations from the orbital motion. Observations on two instruments at the Pulkovo Observatory have been used in this work: the normal astrograph during 1895-1919 and the 26-inch refractor during 1957-2019, as well as the earliest micrometric measurements by V. Ya. (F.G.W.) Struve during 1819-1837. Relative positions of the components determined from observations with the normal astrograph during 1895-1999 are published for the first time. Because of its closeness to the Sun and the spectral class of the components K5V and K7V, 61 Cyg is regarded as a probable candidate parent star of an exoplanet. Because of the combined observations with the 26-inch refractor and the transformation of all the data to a unified system, a gap in the observations from the beginning of the twentieth century has been filled. The modern astrophysical parameters of this star together with data published in the Gaia DR2 survey have been used. To check the orbit, the radial orbital acceleration W has been calculated from our data and found to be in good agreement with the acceleration derived by other authors from spectral observations. Possible periodic deviations from the orbital motion of the star are also discussed.

The results of long-term spectral monitoring of the Herbig Be star IL Cep A are presented. A smooth variation in the parameters of the Нα and Нβ line emission component has been discovered. The helium absorption lines He I λ4922 and 5876 A show seasonal changes, however, these changes do not correlate with changes in hydrogen emission. The radial velocities of the narrow lines D Na I and DIB λ5780, 5796 A correspond to that of the interstellar medium. The hydrogen emission lines are apparently formed in a triple system, including a close pair of B stars and a remote low-mass K–A component. The orbital elements of this system were calculated using an approximate spectral binary model, where a close pair of massive B stars was considered as one massive component. The rationale for this approach for determining the elements of the orbit is given. The orbital period P = 3550 ± 28 days is determined and some other parameters of the orbit are estimated.

Results of our spectral monitoring of the Herbig Ae star HD190073 during 2009-2017 at the Crimean Astrophysical Observatory are presented. Over this time, 116 spectra were obtained in the region of the Hα line and 61 in the region of the HeI and NaI D lines. It was found that the parameters of the circumstellar lines are variable and at least three separate components of the variability can be identified: (a) night to night, (b) interseasonal (τ tens of days), (c) slow (τ years). We assume that the interseasonal variability may be related to modulation of the rotational profiles of the star with a period of about 40 days, while the slow variations may be influenced by a hypothetical binarity of the object, direct signs of which have not yet been been discovered. We confirm that the complicated multicomponent structure of the blue absorption components of the Ca II doublet absorption lines, which have already been discussed for several decades, is also observed in the Hα and NaI D2 lines. These features of these lines are presumably related to the existence of a magnetic field with a complicated configuration in this object. The characteristics of this configuration remain unknown and should be the subject of future investigations. We also assume that the sudden changes in the parameters of the lines after JD2455700 may be related to a transformation in the magnetic field of HD190073 predicted previously in the literature. We believe that further studies of this object should include: (a) repeated direct spectropolarimetric measurements of the magnetic field, (b) a search for cyclicity in measurements of the parameters of the profiles of its lines on a time scale of tens of days (owing to rotational modulation) to several years (traces of the presence of a second component), and (c) a study of the variability of other circumstellar lines formed in the wind (e.g., the FeII (42) triplet line).

High-resolution spectroscopic data for the binary system HD83058 located in the OB association Sco-Cen are presented. The observations were made at the ESO and Sierra Armazones (Chile) observatories over 3 seasons: in March 1998, in 2007-2009, and in May 2013. A total of 41 spectra of the object were obtained. An analysis of the radial velocities of the lines from both system component yielded the orbital elements and an orbital period of P = 2.3650804 ± 0.0000034 days was found. Using a model of stellar atmospheres we separated the spectra of the two components and found their parameters to be Teff = 25700 ± 400 K, logg = 4.27 ± 0.05, and Teff = 19200 ± 600 K, logg = 4.03 ± 0.20 for components A and B, respectively. We confirmed the presence of moving local features in the profiles of the SiIII lines in the spectrum of component A which may be associated either with pulsation activity of the star or with the rotation of spot-like inhomogeneities on its surface. We found that the lines in the spectrum of component B have another type of variability in which the width and depth of almost all the atmospheric lines change in opposite phase on individual dates. It was found that the system is substantially asynchronous. We assume that the desynchronization of the system may arise from gravitational interactions of the system with a third body, since the density of stars within the OB association must be much higher than usual.

The spectroscopic variability of the Herbig Ae/Be star HD 37806 is analyzed on temporal scales from night-to-night, and over individual nights. The observations were made during November 2012 on the ASP-14 Coude spectrograph installed on the 2.6-m ZTSh telescope at the Crimean Astrophysical Observatory. 40 spectra in the region of the Ha and HeI 5876 lines were obtained over 4 nights. An analysis of the observed variability of the profiles of these lines shows that: (a) the variations in the Ha profiles are well explained under the assumption that they are vibrationally modulated by local azimuthal inhomogeneities in the wind zone and (b) the rapid variability of the HeI 5876 line in the form of standing intensity waves in the region of a red absorbing component is additional evidence of the presence of a magnetosphere in HD37806 that contains local accretion fluxes that rotate rigidly in the star’s magnetic field.

The variability of the components A and B of the visual binary system 61 Cyg is analyzed. The observations were made on the normal astrograph of the Pulkovo Observatory from 1956 through 1982 (a total of 296 brightness estimates). A search was undertaken for the periods of the variability of both components of the system with independent application of two periodogram analysis techniques: a sinusoidal approximation and the traditional Scargle method. As a comparison, the complete photometric series including all 296 values of the stellar magnitude and the yearly averages (27 values) were analyzed. This yielded a reliable value of about 15 years for the period of both components and a period of 8.5-9 years for the component 61 Cyg B that coincides with the 9.1-year period of the coronal and chromospheric activity discovered in 1978 by Wilson. 61 Cyg A was also found to have a less significant period of about 6 years, which coincides, to within the limits of accuracy, with a period of 7.5±1.7 years of the coronal and chromospheric activity previously noted by Hempelmann. Yet another less significant period of about 4 years of unknown origin was observed for 61 Cyg B. This may be the second harmonic of the fundamental period. We assume that the low accuracy of the estimated periods may be related to their instability owing to the complicated multicomponent character of the observed variability. A period of about 15 years detected for both components A and B may be related to astroclimatic or instrumental effects.

Results are reported from a spectroscopic study of the Herbig Ae/Be star HD 37806 from 2009 through 2017 using high resolution spectrographs at the Crimean Astrophysical Observatory and the OAN SPM Observatory in Mexico. 72 spectra of this object near the Hα, Hβ, HeI 5876 and D NaI lines are analyzed. The following results were obtained: 1. The type of spectral profile of the Hα line can change from P Cyg III to double emission and vice versa over a time scale on the order of a month. 2. Narrow absorption components are observed in the profiles of the Hα and D NaI lines with radial velocities that vary over a characteristic time on the order of a day. 3. On some days, the profiles of the Hβ, HeI 5876, and D NaI lines show signs of accretion of matter to the star with a characteristic lifetime of a few days. A possible interpretation of these phenomena was considered. The transformation of the Hα profile may be related to a change in the outer latitudinal width of the boundary of the wind zone. The narrow variable absorption lines may be caused by the rotation of local azimuthal inhomogeneities in the wind zone owing to the interaction of the disk with the star’s magnetosphere in a propeller regime. Several current theoretical papers that predict the formation of similar inhomogeneous wind structures were examined. It is suggested that the episodes with signs of accretion in the spectral line profiles cannot be a consequence of the modulation of these profiles by the star’s rotation but are more likely caused by sudden, brief changes in the accretion rate. These spectral observations of HD 37806 should be continued in a search for cyclical variability in the spectral parameters in order to identify direct signs of magnetospheric accretion and detect possible binary behavior in this object.

We present longitudinal magnetic field measurements $\langle B_z \rangle$ for the Herbig Ae primary and the T Tauri secondary in the SB2 system HD 104237. These measurements were carried out using high spectral resolution observations obtained with the High Accuracy Radial velocity Planet Searcher in polarimetric mode, installed at the ESO La Silla 3.6 m telescope. In agreement with previous studies of Herbig Ae stars, the longitudinal magnetic field in the primary is rather weak, ranging from 47 G to 72 G. The secondary component possesses a variable, much stronger magnetic field, up to 600 G, as expected for a magnetically active T Tauri star. We estimated the rotation period of the primary, $P_{\mathrm{rot}}=4.33717\pm0.00316$ d ($=104\pm0.08$ h), from metal line equivalent width variations., Comment: 6 pages, 5 figures, accepted to be published in MNRAS

We present new results of our photometry for the Herbig Be star HD 52721 obtained from January 16 to March 25, 2013. A new data reduction technique is used. Using this technique, we have also reanalyzed the previous results of our photometry for this object pertaining to the period from March 7 to March 28, 2010. The Be star HD 52721 is known as an eclipsing variable with the period P = 1d. 610. Two photometric minima observed during one period are a peculiarity of its photometric variability. They are separated in phase of the period P by 0.5 and differ from one another in depth by 0m. 04. We have also detected additional minima observed at the phases of maximum brightness. We hypothesize that they can be associated with the existence of local azimuthal inhomogeneities rotating synchronously with the orbital motion of the binary component stars in the circumstellar envelope. When processing our CCD frames, we have applied an efficient CCD-frame rejection method that has allowed the accuracy of observations to be increased considerably. The CCD frames have been further processed using the Apex II software package, which is a universal software platform for astronomical image processing. We justify the need for additional photometric observations of HD 52721 in various color bands to confirm the hypothesis about the existence of azimuthal inhomogeneities in the program binary system and to analyze their physical properties.

This paper presents a new hardware and software system that allows not only recording the EMG of different groups of the respiratory muscles but also performing its amplitude-frequency analysis to determine the change in the contribution to the function of breathing of the respiratory muscles and detect early signs of fatigue of the respiratory muscles. The presented system can be used for functional diagnostics of breath in patients and healthy subjects and athletes.

We present first results of the photometric and spectroscopic investigation of the B1/B2 Herbig star HD52721 performed in 2009–2010 at three observatories: Mountain Astronomical Station (Kislovodsk)—photometry, CrAO (Crimea, Ukraine)—spectroscopy, Observatory San Pedro Martyr (Ensenada, Mexico)—high-resolution echelle-spectroscopy. We have also used photometric data from the ASAS survey for 2003–2009. Our analysis has shown that a) the object is a close binary system with the orbital period of 1.610 days composed of two components of similar spectral type (B1–B2); b) the system is surrounded by the common disk-like envelope containing azimuthal inhomogeneity rotating with the orbital period of the system. We present preliminary estimates of the system parameters and discuss its possible nature.

Photometric and high-resolution spectral data on the Be Herbig star HD 52721 from our earlier article [1] are supplemented by new data obtained with an echelle spectrograph mounted on the 2.1-m telescope at the San Pedro Martir Observatory (Ensenada, Mexico). BVR photometry data obtained during 1987-1998 at the Maidanak Observatory (Uzbekistan) are also examined in more detail. This confirms that the phase light curve for an orbital period P = 1d.610 has two minima with different depths separated in phase by 0.5, and reveals a reddening of the object at the phases of the minima. The profiles of atmospheric He I lines in the 4000-4500 A range are found to be broader, shallower, and more asymmetric at the brightness maximum than at the minimum, as expected in close binary systems. Various factors which may influence the formation of the observed atmospheric line profiles are discussed. The observations confirm the hypothesis of a dense disk shaped gas envelope surrounding the system that makes a significant contribution to its overall brightness and contains a global azimuthal inhomogeneity rotating in synchrony with the orbital motion of the system components. We emphasize the need for new photometric observations of HD 52721 in the region of the atmospheric lines, as well as a continuation of the photometric program, in order to confirm the existence of and to analyze the stable, small variations in the light curve of this object.

An analysis of spectra of the well known Herbig Ae/Be star AB Aur obtained with a high resolution Coude spectrograph (R similar to 20000-25000) installed on the 2.6-m Shejn telescope at the Crimean Astrophysical Observatory (Ukraine) and a medium resolution echelle spectrometer (R similar to 14000) on the 2-m Zeiss telescope at the Shemakha Astrophysical Observatory of the National Academy of Sciences of Azerbaijan yielded an unexpected result. It turns out the the variations in the equivalent widths EW of the HeI 5876 and D NaI emission lines have an inverse correlation (r=-0.67 +/- 0.14 and -0.73 +/- 0.10 according to the data from the CrAO and the ShAO, respectively), while the correlation is direct for the H alpha and HeI 5876 lines (r=+0.68 +/- 0.14 and +0.59 +/- 0.14 according to the data from the CrAO and the ShAO, respectively). The Lafler-Kinman method gives a period P=123.7 days for the variation in the EW of these lines. On phase diagrams plotted for this period, the variations in the EW are sinusoidal, with the variations in EW(HeI) and EW(DNaI) in counterphase, while EW(HeI) and EW(H alpha) are in phase. A possible interpretation of this phenomenon is examined. The need for new spectral observations of AB Aur in order to confirm the observed effects on a larger statistical sample is emphasized.

We present the results of our observations of eight magnetic Herbig Ae/Be stars obtained with the X-shooter spectrograph mounted on UT2 at the VLT. X-shooter provides a simultaneous, medium-resolution and high-sensitivity spectrum over the entire wavelength range from 300 to 2500 nm. We estimate the mass accretion rates M_acc of the targets from 13 different spectral diagnostics using empiric calibrations derived previously for T Tauri-type stars and brown dwarfs. We have estimated the mass accretion rates of our targets, which range from 2x10^-9 to 2x10^-7 M_sun/yr. Furthermore, we have found accretion rate variability with amplitudes of 0.10-0.40 dex taking place on time scales from one day to tens of days. Additional future night-to-night observations need to be carried out to investigate the character of M_acc variability in details. Our study shows that the majority of the calibrational relations can be applied to Herbig Ae/Be stars, but several of them need to be re-calibrated on the basis of new spectral data for a larger number of Herbig Ae/Be stars.

New determinations of the mean longitudinal magnetic field for several Herbig Ae/Be stars are presented. The longitudinal magnetic field measurements of MWC 480 reveal the presence of a strong kG field, which was undetected in our previous low-resolution polarimetric observations with FORS 1. The magnetic field geometries of Herbig Ae/Be stars studied with spectropolarimetric time series can likely be described by centred dipoles with polar magnetic field strengths of several hundred Gauss. A number of Herbig Ae/Be stars with detected magnetic fields were recently observed with X-shooter in the visible and near-IR as well as with the high-resolution near-IR spectrograph CRIRES. These observations are of great importance to understand the relation between the magnetic field topology and the physics of accretion flow and accretion disk gas emission.

The influence of three types of respiratory support on the respiratory values in wakeful healthy individuals was studied. Specific changes in the pattern of volumetric and temporal parameters were established for each type of respiratory support. One response to all types of respiratory support was hyperventilation, though of different degrees, and hypocapnia as a consequence. These changes are not connected with the metabolic requirements and are apparently a result of interaction between the mechanisms of automatic and voluntary regulation of respiratory movements.

Photometric and high resolution spectroscopic data for the Herbig star HD 52721 obtained from October 2009 through October 2010 are presented. We confirm the cyclical character of the photometric variability of HD 52721 discovered previously by others. The variability shows up as minima in the light curve of this star which repeat with a period P = 0d.805 and are typical of eclipsing binary systems. ASAS data covering an observation period from September 2003 through December 2009 show that two neighboring photometric minima differ from one another, and the actual orbital period of the system must be twice as high (P = 1d.610). This is confirmed by the spectroscopic data. These show that the center of gravity of the emission Hα line and the profile of the HeI 6678 line with a distinct, bright circumstellar component have a clear correlation with a period of 1d.610. To all appearances, HD 52721 is a close binary system consisting of two class B2 stars with quite similar parameters. We propose that the observed cyclical variations in the circumstellar parameters may be related to the existence of a global azimuthal inhomogeneity within the shell which rotates synchronously with the orbital motion of the system components.

The effect of a head-down tilt on the responses of the external respiration system and the functional capacity of the diaphragm and parasternal muscles were investigated in 11 healthy subjects. A 30-min head-down tilt posture (−30° relative to the horizontal) significantly increased the inspiratory time, decreased the respiration rate and the inspiratory and expiratory flow rates; and increased the airway resistance compared to these values in the vertical posture. There were no significant changes in tidal volume or minute ventilation. The electromyograms (EMGs) of the diaphragm and parasternal muscles showed that the constant values of tidal volume and minute ventilation during head-down tilt could be provided by an increase in the electric activity of the thoracic inspiratory muscles. It was established that the contribution of the thoracic inspiratory muscles increased, while the diaphragms’ contribution decreased, during patient, spontaneous breathing. The maximal inspiratory effort (Muller’s maneuver) during a head-down tilt evoked the opposite EMG-activity pattern: the contribution of inspiratory thoracic muscles was decreased and the diaphragm EMG activity was increased compared to the vertical posture. These results suggest that coordinated modulations in inspiratory muscle activity make it possible to preserve the functional reserve of human inspiratory muscles during a short-term head-down tilt.

We report the detection of weak mean longitudinal magnetic fields in the Herbig Ae double-lined spectroscopic binary AK Sco and in the presumed spectroscopic Herbig Ae binary HD95881 using observations with the High Accuracy Radial velocity Planet Searcher polarimeter (HARPSpol) attached to the European Southern Observatory's (ESO's) 3.6m telescope. Employing a multi-line singular value decomposition (SVD) method, we detect a mean longitudinal magnetic field =-83+-31G in the secondary component of AK Sco on one occasion. For HD95881, we measure =-93+-25G and =105+-29G at two different observing epochs. For all the detections the false alarm probability is smaller than 10^-5. For AK Sco system, we discover that accretion diagnostic Na I doublet lines and photospheric lines show intensity variations over the observing nights. The double-lined spectral appearance of HD95881 is presented here for the first time.

We report the results of our search for magnetic fields in a sample of 16 field Be stars, the binary emission-line B-type star upsilon Sgr, and in a sample of fourteen members of the open young cluster NGC3766 in the Carina spiral arm. The sample of cluster members includes Be stars, normal B-type stars and He-strong/He-weak stars. Nine Be stars have been studied with magnetic field time series obtained over ~1 hour to get an insight into the temporal behaviour and the correlation of magnetic field properties with dynamical phenomena taking place in Be star atmospheres. The spectropolarimetric data were obtained at the European Southern Observatory with the multi-mode instrument FORS1 installed at the 8m Kueyen telescope. We detect weak photospheric magnetic fields in four field Be stars, HD62367, mu Cen, o Aqr, and epsilon Tuc. The strongest longitudinal magnetic field, =117+-38G, was detected in the Be star HD62367. Among the Be stars studied with time series, one Be star, lambda Eri, displays cyclic variability of the magnetic field with a period of 21.12min. The binary star upsilon Sgr, in the initial rapid phase of mass exchange between the two components with strong emission lines in the visible spectrum, is a magnetic variable star, probably on a timescale of a few months. The maximum longitudinal magnetic field =-102+-10G at MJD54333.018 was measured using hydrogen lines. The cluster NGC3766 seems to be extremely interesting, where we find evidence for the presence of a magnetic field in seven early B-type stars out of the observed fourteen cluster members., Comment: 9 pages, 8 figures, 3 tables, accepted for publication in Astronomische Nachrichten

Spectroscopic data taken with a moderate resolution spectrograph in the region of the Hα and Hβ lines are presented for the Herbig B8e star MWC 419. The spectroscopic observations were accompanied by broad band BVR photometric measurements. The observations reveal a variability in the line profiles that is typical of Herbig Ae/Be stars with signs of a strong stellar wind. The greatest changes are observed in the region of the absorption components of the line profiles, which convert the profile from a type P CygII to P CygIII, as well as in the intensities of the central emission components. A model technique is used for quantitative interpretation of this variability and it shows that the P Cyg profile conversion of the absorption component can be explained in terms of a stellar wind model in which its distribution over latitude varies on a time scale of a few days.

Aims.We investigate the photospheric and circumstellar (CS) magnetic field components separately in seven Herbig Ae stars. Methods: The study is based on low-resolution (R˜ 2000 and 4000) spectropolarimetric data collected from 2003 to 2005 at the Very Large Telescope (ESO, Chile) with the multi-mode instrument FORS1. Results: We show that the spectropolarimetric results strongly depend on the level of CS contribution to the stellar spectra. We have improved the determination accuracy of magnetic fields up to the 7sigma level in the two Herbig Ae stars HD 139614 and HD 144432, observed in 2005 when these objects were at a low level state in their CS activity. We have established that at a higher level state of CS activity the polarisation signatures are mainly related to the CS matter. The presence of CS polarisation signatures formed in the stellar wind supports the assumption that the magnetic centrifuge is one of the main mechanisms of wind acceleration. Conclusions: .We conclude that the most effective way to investigate the magnetism of Herbig Ae stars is to monitor their spectropolarimetric behaviour at different stages of CS activity. Obviously, higher-resolution spectropolarimetric observations would extend the sample of spectral lines which can be used to measure magnetic fields at different levels in the stellar atmosphere and CS envelope. These observations will give a more complete insight into the magnetic topology in Herbig Ae stars. Based on observations collected at the European Southern Observatory, Paranal, Chile (ESO programme Nos. 072.D-0377, 073.D-0464, 074.C-0463, and 075.D-0507).

Aims. Recently, several arguments have been presented that favour a scenario in which the low detection rate of magnetic fields in Herbig Ae stars can be explained by the weakness of these fields and rather large measurement uncertainties. Spectropolarimetric studies involving sharp-lined Herbig Ae stars appear to be a promising approach for the detection of such weak magnetic fields. These studies offer a clear spectrum interpretation with respect to the effects of blending, local velocity fields, and chemical abundances, and allow us to identify a proper sample of spectral lines appropriate for magnetic field determination. Methods. High-resolution spectropolarimetric observations of the three sharp-lined (v sini ) Herbig Ae stars HD 101412, HD 104237, and HD 190073 have been obtained in recent years with the HARPS spectrograph in polarimetric mode. We used these archival observations to investigate the behaviour of their longitudinal magnetic fields. To carry out the magnetic field measurements, we used the multi-line singular value decomposition (SVD) method for Stokes profile reconstruction. Results. We carried out a high-resolution spectropolarimetric analysis of the Herbig Ae star HD 101412 for the first time. We discovered that different line lists yield differences in both the shape of the Stokes V signatures and their field strengths. They could be interpreted in the context of the impact of the circumstellar matter and elemental abundance inhomogeneities on the measurements of the magnetic field. On the other hand, due to the small size of the Zeeman features on the first three epochs and the lack of near-IR observations, circumstellar and photospheric contributions cannot be estimated unambiguously. In the SVD Stokes V spectrum of the SB2 system HD 104237, we detect that the secondary component, which is a T Tauri star, possesses a rather strong magnetic field ⟨B z ⟩ = 129 ± 12 G, while no significant field is present in the primary component. Our measurements of HD 190073 confirm the presence of a variable magnetic field and indicate that the circumstellar environment may have a significant impact on the observed polarization features.

The relationship between the sensation of lack of air caused by the addition of carbon dioxide to inhaled air and minute pulmonary ventilation was studied in eight healthy male volunteers. Under the conditions of both natural respiration and controlled artificial ventilation of the lungs, ventilation increased in proportion to the increase in the partial pressure of CO2 in the end-tidal exhaled air. The individual differences in the ventilation responses to CO2 under the conditions of controlled ventilation and natural ventilation are regarded as a property of voluntary control.

Aims. We investigate the spectroscopic behaviour of the young B0e star HD 53367 within a cooperative observing programme conducted from 1994 to 2005. Methods. The data include more than 100 high-resolution spectra collected at the Crimean Astronomical Observatory (CrAO) near Ha, Hβ, He I A 5876, 6678 A, DNa I, and O II λ 6641 A lines. Two spectra obtained at the Observatorio do Pico dos Dias (LNA), in the spectral bands λλ 4575-725 A and 5625-5775 A, were used for spectral classification of HD 53367. The temporal behaviour of the circumstellar lines Ha and Hβ as well as the photospheric lines O II λ 6641 A and He I λ 6678 A were investigated during different stages of the photometric activity of this object. Results. We confirm that the long-term photometric variability of HD 53367 is related to the alternation of two states of this object when the gaseous circumstellar envelope disappears and rises again. Both these processes start near the star and spread to the outlying parts of the envelope. We find that the radial velocities of He I and O II photospheric lines demonstrate a cyclic variability with a period of P = 183.7 days and semi-amplitude K = 19 km s -1 . The radial velocity change is interpreted in the framework of a model in which the star is a component of an eccentric binary system. An orbital solution is derived and the system's parameters estimated. We find that the orbital eccentricity is e = 0.28, and the mean companion separation is 1.7 AU. Conclusions. Based on the estimated parameters, we conclude that the system consists of a massive (∼20 M Θ ) main sequence primary BOe star, and a secondary which is most likely a 5 solar mass pre-main sequence object. We found evidence that the main part of the circumstellar gas in this system is concentrated near the secondary companion. Although the young age of HD 53367, its evolved primary BOe star seems to have already became a classical Be star exhibiting a specific alternation of the B-Be stages.

The results of high-resolution spectroscopy of the peculiar Ae star HD 190073 obtained within the framework of a cooperative observing programme in 1994-2002 are presented. The temporal behaviour of the Hα ,H β ,H γ ,H δ ,H e λ 5876 A, Na  D and other circumstellar line profiles are investigated in detail. Special attention has been paid to the analysis of the deep multicomponent blueshifted Ca  H and K absorption lines. It has been found that the fine structure of their profiles is variable on timescales from months to decades. The analysis of the circumstellar spectrum of HD 190073, rich in shell-like and emission lines with narrow absorption cores, allows us to conclude that all absorption lines and cores are likely to be of photospheric origin. The emission lines are variable in time and demonstrate signs of a stellar wind as well as a dense equatorial circumstellar disk. As a preliminary hypothesis, we propose that a global magnetic field of a specific topology can be responsible for the formation of stable latitudinal stratification of the outflowing gas resulting in appearance of the complex structure of the Ca  H and K line profiles. We emphasise that a measurement of the stellar magnetic field and an investigation of its detailed configuration would be an important step in understanding the nature of HD 190073.

We have calculated the degree and position angle of the polarization of radiation scattered in a magnetized, optically thin or optically thick envelope around a central source, taking into account Faraday rotation of the plane of polarization during the propagation of the scattered radiation and the finite size of the radiation source. The wavelength dependence of the degree of polarization can be used to estimate the magnetic field of the source (a star, the region around a neutron star, or a black hole), and we have used our calculations to estimate the magnetic fields in a number of individual objects: several hot O and Wolf-Rayet stars, compact objects in X-ray close binaries with black holes (SS 433, Cyg X-1), and supernovae. The spectrum of the linear polarization can be used to determine the magnetic field in the vicinity of a central supermassive black hole, where the polarized optical radiation is generated. In a real physical model, this value can be extrapolated to the region of the last stable orbit. In the future, the proposed technique will make it possible to directly estimate the magnetic field in the region of the last stable orbit of a supermassive black hole using X-ray polarimetry.

To clarify the mechanisms of interaction between voluntary and involuntary control of respiratory movements in a waking human, respiratory patterns were studied during self-controlled artificial ventilation used in place of natural breathing. Seven subjects controlled both the duration of artificial inhalations and the flow rate of air at excess pressure, continuously adjusting their actions to obtain the sensation of comfortable breathing. At rest, pulmonary ventilation was higher during self-controlled artificial breathing than during natural breathing. This trend was also noted during exercise. A correlation was observed between the velocity of the movement that started air flow and the artificial ventilation volume (r = 0.91). During self-controlled artificial breathing, the subjects sometimes took natural breaths. Natural inhalations did not influence the beginning or end of an artificial inhalation. Information received from respiratory receptors was assumed to play a certain role in the self-control of artificial breathing.

The results of high-resolution spectroscopy of the Herbig Be star HD 200775 obtained within the framework of a cooperative observing programme in 2000–2002 are presented. A new high-activity phase of the object’s Ha line occurred in the middle of 2001 in full agreement with a 3.68-year periodicity predicted by Miroshnichenko et al. (1998). A complicated picture of the Ha line profile variability near the activity maximum phase turned out to be very similar to that observed during the previous one in 1997. Variations of the radial velocity with the activity phase are detected in He I, Si II, and S II photospheric lines. The observed phenomena are interpreted in the framework of a model in which the star, together with its gaseous envelope, is a component of an eccentric binary system. A preliminary orbital solution is derived, and the system’s parameters are estimated from the radial velocity curves of the Ha emission line. We find that the orbital eccentricity is e ~ 0.3, the mean companion separation is ~1000 R?, and the secondary companion is most likely to be a ~3.5 M, pre-main sequence object. We emphasize the importance of coordinated spectroscopic and interferometric observations at different phases of the object’s activity for further understanding the properties of the system.

We present the results of observations of the Herbig Ae star HD 31648 including high-resolution spectroscopy near the H α , He i l 5876 A and DNa i lines, multi-color photometry and polarimetry. These observations have revealed many features of the observational appearance of HD 31648 similar to those of the “classical” Herbig Ae stars. Among them are spectral manifestations of both the mass loss and the disk accretion onto the star and certain types of line profile variations. The totality of the observed properties of HD 31648 provides evidence in favor of complicated structure in the stellar wind zone, exhibiting latitudinal stratification and containing local inhomogeneities in the form of outflowing streams and density condensations. Structural variations of the stellar wind have been found to correlate with changes in the accretion process in the envelope. The circumstellar environment of HD 31648 is supposed to contain dust particles of different forms manifesting themselves, in particular, in the variable multi-component intrinsic polarization.

We present the results of magnetic field measurements for a sample of 23 young Herbig Ae/Be (HAEBEs) stars and 12 stars with debris disks. The spectropolarimetric data were obtained during four observing runs in 2003-2008 at the European Southern Observatory with the multi-mode instrument FORS 1 installed at the 8 m Kueyen telescope. Among the 23 HAEBEs studied, stellar magnetic fields of about 100-150G have been detected in 11 stars (i.e. ~50%). The presence of circumstellar polarization signatures formed in the stellar wind supports the assumption that the magnetic centrifuge is one of the main mechanisms of the wind acceleration. No field detection at a significance level of 3σ was achieved in stars with debris disks.

We present new results of a spectroscopic and polarimetric investigation of the candidate young Herbig Ae/Be star HD 163296. Twenty two spectra of this object near the H ,H e i5876 and DNa i lines had been obtained in 1992{1995 at the Astrophysical National Laboratory of Brazil (LNA). In addition, forty seven high-resolution spectra in H and H were obtained at the ESO (Chile) in 1991{1992. VRI-polarimetry (about forty measurements of the Stokes parameters Q; U; V in each passband) were carried out at the SAAO (South Africa) in July 17{30, 1995. Striking prole variability has been found in all the lines on time scales from hours to months. Analysis of the proles revealed manifestations of a remote cool shell which is in active interaction with the variable kinemati- cally stratied stellar wind. Signs of cyclic positional vari- ations of the H and H emission peaks were observed during ve nights in July, 1991. Sinusoidal variations of the linear polarization parame- ters detected in July, 1995 are explained in the framework of a model involving magnetized gaseous condensation, rotating in the envelope with the period of 15 days. Marginal detection of circular polarization is also re- ported.

Herbig Ae stars are young A-type stars in the pre-main sequence evolutionary phase with masses of ∼1.5-3 M� . They show rather intense surface activity (Dunkin et al. 1997, MNRAS, 290, 165) and infrared excess related to the presence of circumstellar disks. Because of their youth, primordial magnetic fields inherited from the parent molecular cloud may be expected, but no direct evidence for the presence of magnetic fields on their surface, except in one case (Donati et al. 1997, MNRAS, 291, 658), has been found until now. Here we report observations of optical circular polarization with FORS 1 at the VLT in the three Herbig Ae stars HD 139614, HD 144432 and HD 144668. A definite longitudinal magnetic field at 4.8 σ level, �B z� = −450 ± 93 G, has been detected in the Herbig Ae star HD 139614. This is the largest magnetic field ever diagnosed for a Herbig Ae star. A hint of a weak magnetic field is found in the other two Herbig Ae stars, HD 144432 and HD 144668, for which magnetic fields are measured at the ∼1.6 σ and ∼2.5 σ level respectively. Further, we report the presence of circular polarization signatures in the Ca  K line in the V Stokes spectra of HD 139614 and HD 144432, which appear unresolved at the low spectral resolution achievable with FORS 1. We suggest that models involving accretion of matter from the disk to the star along a global stellar magnetic field of a specific geometry can account for the observed Zeeman signatures.

Models of magnetically-driven accretion and outflows reproduce many observational properties of T Tauri stars. This concept is not well established for the more massive Herbig Ae/Be stars. We intend to examine the magnetospheric accretion in Herbig Ae/Be stars and search for rotational modulation using spectroscopic signatures, in this first paper concentrating on the well-studied Herbig Ae star HD101412. We used near-infrared spectroscopic observations of the magnetic Herbig Ae star HD101412 to test the magnetospheric character of its accretion disk/star interaction. We reduced and analyzed 30 spectra of HD101412, acquired with the CRIRES and X-shooter spectrographs installed at the VLT (ESO, Chile). The spectroscopic analysis was based on the He I lambda 10,830 and Pa gamma lines, formed in the accretion region. We found that the temporal behavior of these diagnostic lines in the near-infrared spectra of HD101412 can be explained by rotational modulation of line profiles generated by accreting gas with a period P = 20.53+-1.68 d. The discovery of this period, about half of the magnetic rotation period P_m = 42.076 d previously determined from measurements of the mean longitudinal magnetic field, indicates that the accreted matter falls onto the star in regions close to the magnetic poles intersecting the line-of-sight two times during the rotation cycle. We intend to apply this method to a larger sample of Herbig Ae/Be stars., Comment: 8 pages, 1 table, 7 figures, accepted for publication in A&A

We evaluated the maximal mouth inspiratory pressure and the EMG patterns of major respiratory and accessory muscles used in the generation of voluntary inspiratory maneuvers during different body positions. Ten healthy subjects (F/M-4/6), the mean age 22.000B10.6 years, participated in the study. The maximal inspiratory mouth pressure (MIP) during Müller's maneuver was measured from residual volume in the standing, sitting, right-sided (RSL) and left-sided lying (LSL), supine, and head-down-tilt (HDT) (3000B0; relatively horizon) positions. EMG of the diaphragmatic (D), parasternal (PS), sternocleidomastoid (SM), and genioglossus (GG) muscles were assessed in each body position. The baseline MIP was 105.3 00B1; 12.0 in men and 59.9 00B110.1 cmH(2)O in women in the standing position and did not appreciable differ in the other positions, except the HDT where it was lower by 23 and 27% in men and women, respectively (P003C0.05). During Müllers maneuver, diaphragmatic EMG activity also was similar in all the body positions, but it was significantly enhanced in the HDT. In contrast, PS EMG showed the highest level of activation in the standing position, taken as the control, reference level, and was lower in the HDT. Activation of SM during the maneuver was near the control in the sitting position, lower in the supine (79%), RSL (85%), LSL (80%), and HDT (72%) positions (P 003C0.05). GG EMG was significantly greater during maximal inspiratory effort in the supine and HDT positions (125and 130%, respectively), while it was lower in the sitting, LRS, and LLS positions (76, 57, and 43%) compared with standing (P 003C; 0.05). We conclude that the inspiratory pressure generated during Muller maneuver is a reflection of complex interactions between several muscle groups during changes in body positions.

We evaluated the maximal mouth inspiratory pressure and the EMG patterns of major respiratory and accessory muscles used in the generation of voluntary inspiratory maneuvers during different body positions. Ten healthy subjects (F/M-4/6), the mean age 22.000B10.6 years, participated in the study. The maximal inspiratory mouth pressure (MIP) during Muller’s maneuver was measured from residual volume in the standing, sitting, right-sided (RSL) and left-sided lying (LSL), supine, and head-down-tilt (HDT) (3000B0; relatively horizon) positions. EMG of the diaphragmatic (D), parasternal (PS), sternocleidomastoid (SM), and genioglossus (GG) muscles were assessed in each body position. The baseline MIP was 105.3 00B1; 12.0 in men and 59.9 00B110.1 cmH2O in women in the standing position and did not appreciable differ in the other positions, except the HDT where it was lower by 23 and 27% in men and women, respectively (P003C0.05). During Mullers maneuver, diaphragmatic EMG activity also was similar in all the body positions, but it was significantly enhanced in the HDT. In contrast, PS EMG showed the highest level of activation in the standing position, taken as the control, reference level, and was lower in the HDT. Activation of SM during the maneuver was near the control in the sitting position, lower in the supine (79%), RSL (85%), LSL (80%), and HDT (72%) positions (P 003C0.05). GG EMG was significantly greater during maximal inspiratory effort in the supine and HDT positions (125and 130%, respectively), while it was lower in the sitting, LRS, and LLS positions (76, 57, and 43%) compared with standing (P 003C; 0.05). We conclude that the inspiratory pressure generated during Muller maneuver is a reflection of complex interactions between several muscle groups during changes in body positions.

We investigated the effect of three types of respiratory support on respiratory parameters in conscious healthy humans. For each type of respiratory support set specific changes in the pattern of volume and temporal parameters. One response to all types of respiratory support was hyperventilating, although varying degrees, and as a consequence, hypocapnia. These changes are not related to the metabolic needs and probably are the result of the interaction mechanisms of automatic and voluntary regulation of breathing movements.

We report on the status of our spectropolarimetric studies of Herbig Ae/Be stars carried out during the last years. For the first time we examined the relation of the measured field strengths with various parameters that characterise the star-disk system. We could show that strongermagnetic fields tend to be found in younger Herbig stars and completely disappear when stars arrive on the ZAMS, indicating that the magnetic fields of Ap/Bp stars are not fossil. New determinations of the mean longitudinal magnetic field for several Herbig Ae/Be stars are presented. The longitudinal magnetic field measurements of MWC480 reveal the presence of a strong kG field, which was undetected in our previous low-resolution polarimetric observations with FORS 1. The magnetic field geometries of Herbig Ae/Be stars studied with spectropolarimetric time series can likely be described by centred dipoles with polar magnetic field strengths of several hundred Gauss. The sharp-lined young Herbig Ae star HD101412 with a strong surface magnetic field has become in the last years one of the best-studied targets among the Herbig Ae/Be stars.

The effect of head-down tilt on respiration and diaphragmal and parasternal muscles activity was investigated in 11 healthy subjects. The short-time (30 min) head-down tilt posture (-30 degrees relatively horizont) increased the inspiratory time (P0.05), decreased breathing frequency (P0.05), inspiratory and expiratory flow rate (P0.05) and increased the airway resistance (P0.05) compared with values in vertical posture. There were no significant changes in tidal volume and minute ventilation. Constant values of tidal volume and minute ventilation during head-down tilt were provided by increasing in EMG activity of parasternal muscles more then twice. It was established that the contribution of chest wall inspiratory muscles increased while the diaphragm's contribution decreased during head-down spontaneous breathing. Maximal inspiratory effort (Muller's maneuver) during head-down tilt evoked the opposite EMG-activity pattern: the contribution of inspiratory thoracic muscles was decreased and diaphragm's EMG-activity was increased compared with vertical posture. These results suggest that coordinate modulations in inspiratory muscles activity allows to preserve the functional possibility of human inspiratory muscles during short-time head-down tilt.