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We report a recent decrease of the Ha emission strength in a bright Be shell star zeta Tau. The decrease of emission is caused presumably by depletion of the material in the circumstellar disc which resulted in disappearance of pronounced long term radial velocity and V/R variations. The period analysis of the equivalent width data gives the period of 132 days for the Ha equivalent width and about 70 days for the He I 6678 A line.

For the investigation of possible variations of the solar rotation, sunspots and sunspot groups are very often used as tracers, mainly because of the long term data sets available from various observatories. Until now, for the investigation of temporal variations of the solar rotation using sunspot groups as tracers, the Kanzelhoehe data set was analysed only for the period 1947-1981. Our aim is to provide a continuation of that previous investigation. For this reason we processed Kanzelhoehe sunspot drawings for solar cycles nos. 20-23 (manual method) and Kanzelhoehe white light images for solar cycle no. 24 (automatic method), covering almost the 41 year period, 1964 - 2015. When both methods for the heliographic positions determination have been used, it is important to compare them. Here we present the results of the manual versus automatic method comparison (differential rotation coefficients for both methods, differences in the identi cation of the sunspot groups, differences in the number of identi fied sunspot groups, etc.) performed for the year 2014.

One of main issues of space weather is the timely prediction of strong geomagnetic storms, mainly caused by coronal mass ejections (CMEs) arriving at Earth. However, with current knowledge on CMEs, we are not yet able to predict the arrival time, velocity and magnetic field, or even if it will hit or entirely miss the Earth. Therefore, an empirical statistical model was established and implemented that can be used as an early geomagnetic storm warning. For every detected CME, the alert system provides a probability estimation of both arrival and geoeffectiveness using near‐real time remote observations of CMEs and associated flares. The probability estimation for CME arrival resulted from an analysis of front‐sided halo CMEs. For each of these CMEs the relationship with an Interplanetary CME (ICME) was identified based on in‐situ data. As such an empirical probabilistic relationship was established for the CME arrival based on the source position. The statistical geoeffectiveness model was set up using a dataset of front‐sided, solar flare‐associated CMEs and association was made with a specific Dst (disturbance storm time) index. This sample contains geoeffective and non‐geoeffective CMEs. The results of an extensive statistical analysis confirmed some previously known connections between remote solar properties and geomagnetic storms, namely the importance of CME speed, apparent width, source position and associated solar flare type. We quantify these relationships and use them to construct a statistical model for predicting the probability of geomagnetic storm level. Both probability models for CME arrival and geoeffectiveness are combined to provide a geomagnetic storm alert in case of CME detection. This work has received funding from the European Commission FP7 Project COMESEP (263252).

A sample of 211 front-sided, flare-associated CMEs, having a minimal speed of 400 km/s, were randomly selected from the LASCO/SOHO catalog and associated with a disturbance storm time (Dst) index. This sample includes geoeffective, non-geoeffective and CMEs which missed the Earth. The latter was derived using the in-situ data and CME-ICME-Dst list made by Richardson&Cane (2010). Statistical analysis is employed to detect relationships between CME parameters, flare parameters and the Dst value. The influence of “CME trains” is also investigated. We present the results of the statistical analysis, which will be used to make an empirical model for the predictions of geomagnetic activity based on the remote sensing of CMEs using L1 coronagraph. This work has received funding from the European Commission FP7 Project COMESEP (263252).

Coronal Mass Ejections (CMEs) are very important in terms of space weather because they can be highly geoeffective. As part of the FP7 project COMESEP (COronal Mass Ejections and Solar Energetic Particles: forecasting the space weather impact), a statistical analysis is being carried out in order to investigate the impact of CME parameters and their associations to geomagnetic storms. A list of 225 front‐sided, flare associated CMEs, with a minimal speed of 400 km/s, were randomly selected from the LASCO/SOHO catalog and associated with a specific Dst (disturbance storm time) index. This way a sample was made containing both geoeffective, non‐ geoeffective and CMEs which missed the Earth. The last was derived using the in‐situ data and CME‐ICME‐Dst list made by Richardson&Cane (2010). Statistical analysis was then applied to detect relationships between CME parameters, such as speed, width, source region location, brightness, and the Dst value. In case of flare related CMEs, the X‐ray intensity and class were also included. We also investigated how much the occurrence of multiple CMEs increases the probability of large Dst values.

Postoji nekoliko različitih baza podataka koje sadrže informaciju o pozicijama sunčevih pjega i grupa sunčevih pjega i razlikuju se po formatu i preciznosti, npr. GPR (Greenwich Photoheliographic Results) i SOON/USAF/NOAA (Solar Optical Observing Network/United States Air Force/National Oceanic and atmosferic Administration). Cilj ovog rada jest provjeravanje preciznosti SOON/USAF/NOAA baze podataka i usporedba iste s GPR bazom podataka. U tu smo svrhu koristili treću bazu podataka, bazu podataka Kanzelhöhe opservatorija, kao mjerodavnu u usporedbi položaja grupa pjega.

We collected rich series of RV measurements covering last 110 years and photometric observations from the past 6 primary eclipses, complemented them by our new observations and derived a new precise ephemeris and an orbital solution of epsilon Aur., Comment: accepted and published in IBVS (paper No. 5937)

There are several data sets containing information about the positions of sunspots and sunspot groups that differ in format and precision, e.g. GPR (Greenwich Photoheliographic Results) and SOON/USAF/NOAA (Solar Optical Observing Network/United States Air Force/National Oceanic and Atmosferic Administration). The aim of this paper is to check the precision of the SOON/USAF/NOAA data set and compare it with the GPR data set. For this purpose, we have used a third data set, the Kanzelhöhe Observatory data set, as a basis of sunspot position measurments comparison. The positions of selected sunspot groups in the digitized Solar Observatory Kanzelhöhe drawings were determined with a special software Sungrabber. The selected groups consisted mostly of single sunspots (Zürich types H and J) from the years 1972 and 1993 belonging to the similar phases of the solar activity cycles. The determined Kanzelhöhe sunspot group coordinates were compared with those from GPR for the year 1972 and SOON/USAF/NOAA for the year 1993. The rotation velocities calculated for sunspot groups observed at Kanzelhöhe were compared with the ones obtained from the two data sets mentioned above in the same observing periods. With the assumption of constant precision of Kanzelhöhe drawings, it was established that SOON/USAF/NOAA data are somewhat less precise than the GPR ones.

The aim of the present analysis is to forecast the strength of the next solar maximum of the 24th cycle. We correlate the relative sunspot numbers in the epochs of solar activity minima and maxima. Using this method, the estimated relative sunspot number (also called the Wolf number) of the next solar maximum is in the range 67 - 81, i.e., about 40 % below the peak sunspot number of 121 for cycle No. 23.

The aim of the present analysis is to forecast the strength of the next solar maximum of the 24th cycle. We correlate the relative sunspot numbers in the epochs of solar activity minima and maxima. Using this method, the estimated relative sunspot number (also called the Wolf number) of the next solar maximum is in the range 67 - 81, i.e., about 40 % below the peak sunspot number of 121 for cycle No. 23.

52 photographic and 651 electronic spectra were disentangled using the program KOREL. This led to the detection of a number of weak absorption lines originating in the atmosphere of the accretion disk. So far, the detection of this disk spectrum was only reported for the Si 6347 and 6371 doublet. (2) The basic spectrophotometric quantities of 15 absorption lines of the primary were measured and corrected for the orbital light changes in order to eliminate the contribution of the secondary light to the observed continuum level. After the correction, a significant phase dependency of the spectral-line characteristics near the primary eclipse was detected. In all probability, another so far unknown absorption-line spectrum was thus found. This spectrum may be due to additional absorption of light of the primary in one of the jet-like structures and in the spherical gas envelope surrounding the accretion disk. Both these structures are seen projected against the primary during its eclipse.

Based on several published photometric and spectroscopic studies, V379~Cep (HR~7940) was identified as a 99.76 day eclipsing binary composed of two unusually-low-mass B type stars with projected rotational velocities of 15 and 55 km/s. Our investigation of new series of spectra and UBV observations from several observatories shows that the object is actually a quadruple system: the two observed sets of spectral lines belong to two primaries of two different binaries. The narrower lines belong to component Aa with 99.76 day orbital period while the broader ones belong to component Ba with 159.3 day period. Both binaries revolve around a common centre of gravity with a period of about 6200 days ; this motion is measurable via the change of the systemic velocities of both binaries. Our result resolves the problem of anomalous masses. It is probable that the masses of all four bodies are quite normal for somewhat evolved stars. But the ultimate test must come from interferometric resolution of the AB pair of binaries ; it might be expected that the separation can reach about 40 mas. There is a very good chance that the continuing systematic observations will permit accurate determination of all four individual masses.

Context: Several binaries with masses anomalously small for their observed spectral types have been discussed in the astronomical literature and interpreted as the result of envelope ejection. V379 Cep is one of these objects. Aims: We obtained new series of electronic spectra and UB{;};V photometry of V379 Cep and analysed them in an effort to check whether the conclusion about its anomalous masses may not be premature. Methods: Reduction of new spectra was carried out in the IRAF and SPEFO programs. New photometry was reduced and transformed to the standard system using the HEC22 program. Orbital elements were derived with the FOTEL program and via disentangling with the program KOREL. The final combined solution was obtained with the program PHOEBE. Some initial period searches were carried out using the phase dispersion minimalization technique. Results: We found that the second system of spectral lines seen in the spectra of V379 Cep does not belong to the secondary but to the primary of another binary Ba + Bb (orbital period of 158.71 ° ± 0.17 °), which constitutes a quadruple system with the narrow-lined 99.7638° ± 0.0006° eclipsing binary Aa + Ab (for which we report probable detection of the secondary and derive improved period and orbital elements). The mutual motion of the two binaries A + B around the common centre of gravity is also observable, and the probable orbital period is (7878 ± 77) days. Our result shows that the components Aa and Ba are somewhat evolved but removes the reported discrepancy of anomalously small masses. Conclusions: .We find that V379 Cep is an astrophysically interesting quadruple system for which a future combination of interferometry, spectroscopy, and photometry can provide individual masses of all four bodies.

Context: Understanding large-scale mass exchange in binaries also requires studies of complicated objects in the rapid phases of the process. β Lyr is one such object. Aims: Our goals were to analyse 52 photographic and 651 electronic spectra of β Lyr to obtain additional information about circumstellar matter and to investigate spectrophotometric information for the first time. Methods: Improved quadratic ephemeris was derived via orbital solution with the FOTEL program. The spectra were disentangled using the KOREL program. Spectrophotometric quantities of 15 stronger absorption lines of the primary were measured and corrected for the orbital continuum variations using the fluxes calculated from a fit of the light curves with the BINSYN program. Central intensities of the V and R peaks of the Hα emission line were measured and corrected for the orbital light changes using the R-band light curve numerically modelled with the program PERIOD04. Results: Disentangling of photographic and electronic spectra led to the detection of weak absorption lines originating from the pseudophotosphere of the accretion disc. This way, a rich line spectrum of the accretion disc, not limited to only two previously known Si II 6347 and Si II 6371 lines, was obtained. A projected rotational velocity of 180 km s-1 was estimated for the disc spectrum. Such a value agrees well with the assumption of the Keplerian rotation of the outer layers of the accretion disc. After the correction, a pronounced increase of the strength of all absorption lines around phases of the primary eclipse was found. We argue that this is due to additional absorption of the light of the primary in one of the jets and/or scattering envelope above the accretion disc of the gainer. The net intensity of the V peak of Hα shows no orbital variation, but a possible 271-d periodicity. The net intensity of the R peak shows mild orbital changes and a slow change over a cycle of about 2780 days. These results seem to support the earlier conclusion that the Hα emission originates in the jet-like structures. Conclusions: .All new findings support the current picture that the circumstellar structures of β Lyr consist of a thick accretion disc, bipolar jets, and a scattering envelope above the disc.

Aims.We include existing photometric and spectroscopic material with new observations in a detailed study of the Be+F binary V360 Lac. Methods: .We used the programs FOTEL and KOREL to derive an improved linear ephemeris and to disentangle the line profiles of both binary components and telluric lines. The BINSYN software suite (described in the paper) is used to calculate synthetic light curves and spectra to fit the {; ; UBV}; ; photometry, an {; ; IUE}; ; spectrum, blue and red ground-based spectra, and observed radial-velocity curves. Results: .The observations provide evidence of circumstellar matter in the system. The system model shows that the Be primary star is critically rotating, and that the synchronously rotating secondary star fills its Roche lobe. The primary star has a mass of 7.45⊙ . Radial-velocity observations establish a mass ratio of 0.163. Light curve synthesis demonstrates that the observed light curves are controlled largely by tidal distortion and irradiation of the massive primary by the less massive secondary. Synthetic spectra fit both blue and red observed spectra with the exception of spectral lines affected by circumstellar matter in the system. The synthetic spectra allow for gravity darkening and are consistent with critical rotation of the primary. Synthetic spectrum fits to a dereddened {; ; IUE}; ; spectrum produce a calculated system distance of 512 pc. This distance is 2σ beyond the Hipparcos distance.

New photoelectric U B{;V}; and BV RI observations, secured during August-November of 2002 at two observatories distant in local time are analyzed together with two earlier photometric data sets and all available radial velocities to derive the most accurate ephemeris of the binary and to set limits on its basic physical elements. These observations were obtained as a support for a high-dispersion spectroscopic study, results of which will be published separately. It was found that radial velocities and photometric observations spanning 53 years can be reconciled with the linear ephemeris T_prim.min.=HJD 2 440 182.25628(46) + 0698095113(29)d × E, where the rms errors of the last digits are given in brackets. Masses of the stars are 1.02 \fms and 0.97 \fms and the binary separation is 4.170 Ro. There is still a large uncertainty in the stellar radii. We also report the discovery of rapid light variations on a time scale of hours seen in the U band light curve and offer a few thoughts on the future investigation of this binary.

Photometric and spectroscopic monitoring of the B star HD 6226 resulted in the finding that this object is a new bright Be star with a clear positive correlation between the brightness and emission-line strength. The emission-line episodes are relatively short and seem to repeat frequently which makes this star an ideal target for studying the causes of the Be phenomenon. The general character of the light variations, the low v sin i = 70 km s-1 and the very pronounced line asymmetries of the He I 6678 line, seen both outside and during emission-line episodes, are all attributes which make HD 6226 phenomenologically very similar to the well-known Be star &omega ; CMa. Radial velocities of the deepest parts of the metallic and He I 6678 absorption lines vary with a strict period of 2.61507 d over the whole time interval covered by the observations, the velocities of the broad outer wings of the same lines varying in anti-phase and with a lower amplitude. This periodicity could not be found in the radial-velocity variations of the sharp core of H&alpha ; . There is some indication of variability on a time scale of 24-29 days but our data are insufficient to prove that conclusively. A comparison of the line spectrum obtained outside emission episodes with synthetic spectra, standard dereddening of U BV magnitudes and Hipparcos parallax all agree with the conclusion that HD 6226 is a star with the following basic properties: Teff , = 17 000 K, log g = 3.0 [cgs], mass of 5m.s and radius of 11 Ro. The strong emission-line episodes may appear regularly, in a cycle of 630 days but with different durations of individual cycles. HD 6226 is probably one of the first B stars for which the Be nature was predicted on the basis of the character of its light and colour changes.

Stable recurrent sunspot groups from the Greenwich data set which were identified in at least two subsequent solar rotations were traced. The solar rotation was determined by the period method from the time difference of the two central meridian passages of each of the 327 identified groups. Sidereal rotation periods were calculated from the synodic ones by a seasonal-dependent procedure taking into account the details of the Earth's motion around the Sun. Growing recurrent sunspot groups rotate on the average faster than decaying recurrent sunspot groups, while sunspot groups of all types taken together rotate faster than both growing and decaying recurrent sunspot groups. A north-south rotational asymmetry and a cycle-dependence of rotational velocity of recurrent sunspot groups were analyzed. Positive rotation velocity deviations are larger, but less numerous than the negative ones. Signatures of torsional oscillations were not found analyzing the rotation velocity residual of recurrent sunspot groups as a function of the distance from the average latitude of activity.

An analysis of numerous homogenized UBV photoelectric observations and red spectra of the Be star V832 Cyg from several observatories led to the following principal findings: 1. Pronounced long-term light and colour variations of V832 Cyg result from a combination of two effects: from the gradual formation of a new Be envelope, and from an asymmetry and a slow revolution of the envelope (or its one-armed oscillation). The colour variations associated with the envelope formation are characterized by a positive correlation between brightness and emission strength, typical for stars which are not seen roughly equator-on. 2. The V magnitude observations prewhitened for the long-term changes follow a sinusoidal orbital light curve with a small amplitude and a period of 28.1971d which is derived from observations spanning 43 years. This independently confirms a 12-year old suggestion that the star is a spectroscopic binary with a 29-d period. V832 Cyg thus becomes the fifth known Be star with cyclic long-term V/R variations, the duplicity of which has been proven, the four other cases being ζ Tau, V923 Aql, γ Cas and X Per. Therefore, the hypothesis that the long-term V/R variations may arise due to the attractive force of the binary companion at certain phases of the envelope formation is still worth considering as a viable alternative to the model of one-armed oscillation. 3. We have shown that the RV and V/R variations of the Hα and He I 6678 emission lines are all roughly in phase. In particular, the He I 6678 emission also moves with the Be primary which differs from what was found for another Be binary, \varphi Per. 4. We derived the orbital elements and found that in spite of the remaining uncertainties, the basic physical properties of the 28.2d binary are well constrained. 5. The light minimum of the orbital light curve occurs at elongation when the Be star is approaching us and the object becomes bluest in (B-V) and reddest in (U-B) at the same time. This may indicate that a part of the optically thick regions of the envelope is eclipsed at these orbital phases. Guest investigator, Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics, National Research Council of Canada. Also based on observations from Castanet-Tolosan, Hvar, Ondrejov, Pic-du-Midi, Rozen, San Pedro Mártir, Toronto and Xing-Long Observatories and on photoelectric photometry by AAVSO members. Tables 3, 5-7 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/387/580}

φ Per (HD 10516, HR 496) is a well known spectroscopic Be binary, with a 126.7-day period, which consists of B0.5IV primary ana a compact secondary (Gies et al., 1998). Its complex photometric behaviour including the long-term, phase locked and rapid light variations are described in Bozic et al. (1995). For the rapid variations they disclosed a formal 0.66-day period while from HIPPARCOS Hp photometry Hubert & Floquet (1998) found the value of 0.470 days.

We investigate the character of light variability of the bright Be star OT Gem. Two phases of the long-term light changes were distinguished: - a quiet phase which is characterized by mild light changes; and - an active phase in which the sudden increase of brightness up to 0.4 in V occur. During the active phase, a cyclic oscillation of brightness of a period between 70 and 80 days is present, with the mosr probable value being 71.89 days. A positive correlation was found between the light and colour variations and the emission strength in both phases.

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Measured positions of sunspot groups that differ in format, precision and observing procedure are collected from various data sets: GPR (Greenwich Photoheliographic Results), SOON/USAF/NOAA (Solar Optical Observing Network/United States Air Force/National Oceanic and Atmospheric Administration), as well as from the Kodaikanal and Debrecen observatories. Kanzelhöhe and Kandilli Observatory currently provide the digitized sunspot drawings, from which the positions of selected sunspot groups are determined with a special software Sungrabber. The rotation velocities are calculated from the position data. The aim of this work is to compare and to check the precision of the mentioned data sets using the Kanzelhöhe Observatory data set as the reference basis of sunspot position measurements. The selected groups (about 40% consist of single sunspots Zürich types H and J) are from the years 1972 and 1993 belonging to similar declining phases of two solar activity cycles. The occurrence of some systematic differences of the sunspot group positions and rotation velocities suggests the need for a more detailed analysis of the data accumulation procedures.

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Solar activity proxies are needed for studies of the long term behaviour of the solar activity cycles. Cosmogenic isotopes like ^{;14};C are influenced also by geomagnetic field variations. We study the influence of such variations on the global behaviour of solar activity measured by methods of non linear dynamics.

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