Radial velocity measurements of the chromospherically-active stars (II)

From two sets of the spectroscopic observations covering a ten year period we have obtained 59 radial velocities of the chromospherically-active star HD 28591 = V492 Per. It is a G9III single-lined spectroscopic binary with a period of 21.2910 days and a circular orbit. Thev sini of 24.6 km s^–1, results in a minimum radius 10.3R . We estimate a distance of 165 ± 40 pc and an orbital inclination of 65 ± 25 degrees. The secondary is probably a mid to late-type K dwarf. The star is brighter than the limiting magnitude of theBright Star Catalogue. The mean photometric and the orbital periods are identical within their uncertainties. Since the star fills a significant fraction of its Roche lobe, about 62%, the photometric light curve may be the result of starspots and a modest ellipticity effect.Visiting astronomer, Kitt Peak National Observatory, NOAO, operated by AURA, Inc., under contract with the NSF     

Long–term Photometry of RT Lacertae: 2. Further Evidence fo a Circumstellar Envelope and MAss Accretion

The light curves, obtained by the authors of the present paper during the period 1978–1992, of the chromospherically active binary system RT Lac were examined. The average (B–V) colour indices were obtained and corrected for the interstellar extinction. Spectroscopic studies indicate that the less massive component may be taken as G8. The light curve analysis indicates that the less massive, larger component fills its corresponding Roche lobe. Both photometric and spectroscopic observations compel one to draw a conclusion that circumstellar matter does exist around the binary system. A colour excess caused by this matter is found to be 0.278 for B–V colour at mid–secondary eclipse. On the basis of photometric colour indices alone, the components of RT Lac are classified as G3–4 and G8. If we use the observed radial velocities of the less massive subgiant star from Ca II emission lines and from other optical lines we find for the mass of the more massive component as 1.34–1.70 M. This mass range corresponds to the main sequence late F stars. The common envelope hypothesis and mass function and also blending of the spectral lines of more massive component point out that it should be at most a late F type main sequence star.     

Spectroscopy of CN Orionis

Two outbursts and a minimum phase of the dwarf nova CN Orionis have been observed spectroscopically. One outburst was covered almost completely. The outburst spectra show periodic variations of the absorption lines which are interpreted with the formation of an elliptic disc during outburst stage. During decline from outburst a narrow emission line appears in the core of the broad H absorption line. The balmer decrement in the outburst phase is much steeper than in the minimum phase. This implies that during the outburst the emission line region is located more outward in the disk. The semi amplitude of the radial velocity curve was determined to K1=152 km/s±10 km/s. Using the photometric orbital period and an assumption about the inclination angle the approximate system parameters could be derived.Based on observations colleted at the European Southern Observatory, La Silla, Chile and at Mount Stromlo Observatory, Canberra, Australia.Paper presented at the IAU Colloquium No. 93 on Cataclysmic Variables. Recent Multi-Frequency Observations and Theoretical Developments, held at Dr. Remeis-Sternwarte Bamberg, F.R.G., 16–19 June, 1986.     

Synchronization features of the magnetic nova V1500 Cyg

An analysis of an eleven-year photometric study of the first magnetic nova V1500 Cyg from observations made at the Crimean Observatory is presented. The data indicate the existence of a beat period caused by rotational-orbital asynchronization as well as its increase with time. The current rotational period of the primary component — a magnetic white dwarf — was calculated for each year by using the current values of the beat period and a constant value for the orbital period. It is shown that rapid synchronization of the components has not occurred uniformly with time: the rate of increase of the rotational period of the white dwarf was during 1977–1979 and over the next ten years. This would lead to synchronization of the rotational and orbital periods over about 230 year if remains constant at 2.7 · 10^–8.Translated fromAstrofizika, Vol. 39, No. 2, pp. 193–199, April–June, 1996.     

A detailed photometric study of the young stellar cluster NGC 2244

We present a brief status report on our ongoing extensive and detailed Walraven photometric observations of the young stellar cluster NGC 2244 in the Rosette Nebula. The observational and reduction procedure is described together with the first results on membership, extinction and detection of pre-Main-Sequence stars.Based on observations collected at the European Southern Observatory (ESO) and at the Observatoire de Haute Provence (OHP, CNRS).Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain.     

Spectroscopic observations of parsamian 21

This work presents spectroscopic observations of Parsamian 21, which has been shown recently by Staude and Neckel to be a fuor-type star. A list of identified absorption lines is given. The results are compared with previous spectroscopic observations over the period 1966–1990. It is shown that the H line profile changed during this period; according to the observations of 1986, the center of the H absorption line was shifted by –140 km/sec from ₀ and reached –600 km/sec at the line edge. It follows from the presented lightcurve that the star has undergone brightness variations of nearly three magnitudes and most likely became a fuor before 1902.Translated fromAstrofizika, Vol. 39, No. 2, pp. 227–235, April–June, 1996.     

Photometry of TT Arietis

An analysis of data spanning 24 years shows that a secondary 20^m periodicity is a persistent feature in photometric observations of TT Ari. This period decreases from 27^m in 1961 to 17^m in 1985. The 4^d beat period of 3 _. ^h 2 photometric and 3 _. ^h 3 spectroscopic periods is also apparent in observations of 1966.Paper presented at the IAU Colloquium No. 93 on Cataclysmic Variables. Recent Multi-Frequency Observations and Theoretical Developments, held at Dr. Remeis-Sternwarte Bamberg, F.R.G., 16–19 June, 1986.     

Further evidence for the binary nature of HR 3084

New photometric and spectroscopic observations yield further evidence for the binary nature of the early-type star HR 3084. Shape and small amplitude of the visual and IR light curves indicate that the light variations are essentially due to ellipsoidal effects rather than to Cep variability.Based on observations collected at the European Southern Observatory, La Silla, Chile.     

Continuum distributions and line profiles of UX UMa-type novalike systems

Combined UV, optical and, in part, IR continuum distributions of the UX UMa-systems CPD-48°1577, V3885 Sgr, RW Sex and of the recently discovered cataclysmic system PHL 227 were determined from multi-wavelength spectroscopic and photometric data to search for general characteristics of these systems. The observed variations of the UV to IR spectroal indices are qualitatively very similar for all systems, whereas the absolute values show significant differences in the far and near UV ranges. The wavelength dependence of the optical and IR spectral indices as well as the variations of the Balmer line profiles lie within the range of model spectra of optically thick and stationary accretion disks with stellar atmosphere characteristics. The different behavior of the far UV spectral indices can be explained by the excess radiation from an extended and optically thick boundary layer, which depends mainly on the orbital inclination.Based on observations collected at the European Southern Observatory, La Silla, Chile, and with the International Ultraviolet Explorer Satellite at the Villafanca ground station.Paper presented at the IAU Colloquium No. 93 on Cataclysmic Variables. Recent Multi-Frequency Observations and Theoretical Developments, held at Dr. Remeis-Sternwarte Bamberg, F.R.G., 16–19 June, 1986.     

The contact binary AE phoenicis — An analysis from deconvoluted spectra

A method is described for an analysis of deconvoluted stellar spectra, and applied to new spectroscopic observations of the close eclipsing system AE Phuenicis, obtained with the 1.52 m telescope of the Southern European Observatory at La Silla, Chile, Results are presented for the rotational velocities of this variable, together with a proposed model of the system.Paper presented at the Lembang-Bamberg IAU Colloquium No. 80 on Double Stars: Physical Properties and Generic Relations, held at Bandung, Indonesia, 3–7 June, 1983.     

Photometric monitoring of 2060 Chiron''s brightness at perihelion

The results of photometric and spectroscopic observations of comet/asteroid 2060 Chiron carried on at the Observatório do Pico-dos-Dias (Brazil), at the European Southern Observatory (Chile) and at the Mauna Kea Observatory (Hawaii) during 1996 are presented. The analysis of the photometric data shows that even at a minimum of brightness 2060 Chiron presents some activity. The absolute magnitude, H_v, varied from 6.79 in February to 6.22 in March. Therefore 2060 Chiron is still in a minimum of activity close to that of 1983–1985 and of 1994–1995.     

9,6-Year periodicity of symbiotic nova RT Ser (1909) during the outburst decay from 1940 to 1994

The behavior of the symbiotic nova RT Ser from 1940 to 1994 from photographic observations made at the Gissar Observatory (1940–1978) and BVR-band observations at the Crimean Observatory (1983–1994) is analyzed. The outburst lightcurve shows a linear decline at a rate of 0^m.06 per year. It appears from the nature of the outburst attenuation that the fading, having already lasted about 80 yr, is still continuing. Judging from the color indices, the principal contribution to the visible light from the system is made by a cool, late-type red giant and hot gas the source of which is, as yet, unknown. The photometric variability observed in the BVR bands with a characteristic time of 10 yr is confirmed by photographic observations of 1928–1978. The period determined from all the data is 9.6 yr and is most likely orbital.Translated fromAstrofizika, Vol. 39, No. 1, pp. 31–40, January–March, 1996.     

The photometric and spectroscopic variability of 1329-294

Photometric and spectroscopic observations of the poorly documented cataclysmic variable 1329-294 are presented. No definite period neither on a long nor on a short time scale could be derived from the photometric data. The radial velocity curve of the emission lines has been used to improve the known orbital period and to confine the primary mass to a value within the Chandrasekhar limit.Based on observations collected at the European Southern Observatory.     

Caii H and K spectroscopic observations in active binary systems

We have performed high resolution spectroscopic observations of five active binary systems in the Caii H and K lines at La Palma Observatory. We present the absolute fluxes calculated at the surface of the stars and we discuss the spectral characteristics observed, presence of double emissions and phase variations.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain.     

The new helium-weak star HR 446

The CP star HR 446 (HD 9531, B8p V,m=5.69) is one of the CP stars with no definitely assigned peculiarity type. In this contribution it is shown by application of the synthetic spectra, that the star is a helium-weak type of the titanium-strontium subgroup. Photometric observations confirmed the rotational period of 0.6684 d discovered earlier. Our photometric observations do not permit to find rapid variability exceeding 0.005 mag within the limits of 5–300 min.Paper presented at the 11th European Regional Astronomical meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain.     

Multicolor photoelectric and photographic observations of the long-period variable Y Ori

Results of observations of the long-period variable Y Ori are presented. The photoelectric observations in UBVR were made at the 60-cm telescope of the high-altitude Maydanak station of the Tashkent Astronomical Institute during the autumn of 1989. The UBVR lightcurves as well as the variations in the color indices U-B, B-V, and V-R are presented. The photographic observations were made at the 40 Schmidt telescope of the Byurakan Observatory and at the 70-cm Maksutov telescope of the Abastumani Observatory. A nebulosity was discovered around Y Ori in red light near the brightness maximum. Such a formation is observed for the first time, not only for Y Ori but also for long-period variables in general. The obtained results are discussed in this work.Translated fromAstrofizika, Vol. 38, No. 1, pp. 5–15, January–March, 1995.     

The eccentric orbit of the short-period eclipsing binary V 1010 Oph

Radial velocity observations of V 1010 Oph obtained at Asiago from 23 spectra combined with those published by Guinan and Koch (1977) reveal a significant eccentricity (e0.20±0.03) with a periastron angle close to 90° at 1 level. This underlines the need for a new analysis of the light curve for photometric elements.On leave from Konkoly Observatory, Budapest, Hungary     

Photometric and spectroscopic investigation of the oscillating Algol type binary: EW Boo

We obtained the physical and geometrical parameters of the EW Boo system, which exhibits short period and small amplitude pulsations as well as brightness variations due to orbital motion of components. Towards this end we carried out photometric observations at Ankara University Kreiken Observatory (AUKO) as well as spectroscopic observations at TUBITAK National Observatory (TNO). The light and radial velocity curves obtained from these observations have been simultaneously analyzed with PHOEBE and the absolute parameters of the system along with the geometric parameters of the components have been determined. Using model light curves of EW Boo, light curve regions in which the pulsations are active have been determined and as a result of analyses performed in the frequency region, characteristic parameters of pulsations have been obtained. We find that the results are compatible with current parameters of similar systems in the literature. The evolutionary status of the components is propounded and discussed.     

A study of the magnetic and velocity fields in an active region

A time sequence of magnetograms and velocity-grams in the H and Fe i 6569 Å lines has been made at a rate of 12 h^–1 of McMath Region 10385 from 26 to 29 October, 1969. The 14 flares observed during this period have been studied in relation to the configuration and changes in the magnetic and velocity fields. There was little correlation between flare position and the evolutionary changes in the photospheric magnetic and velocity field, except at large central meridian distances where the velocity observations suggested shearing taking place at flare locations. At central meridian distances > 30° we found that flares are located in areas of low line-of-sight photospheric velocity surrounded by higher velocity hills. The one exception to this was the only flare which produced a surge. Blue-shifted velocity changes in the photosphere of 0.3 to 1 km s^–1 were observed in localized areas at the times of 8 of 14 flares studied.Visiting Astronomer, Kitt Peak National Observatory.Operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation.     

Spectroscopy and optical/IR photometry of the cataclysmic variable CPD-48°1577

The photometric variability of CPD-48°1577 in the optical and IR ranges is discussed. The structure and variation of prominent emission line profiles are investigated. An estimate of the distance is given.Paper presented at the Lembang-Bamberg IAU Colloquium No 80 on Double Stars: Physical Properties and Generic Relations, held at Bandung, Indonesia, 3–7 June, 1983.Based on data collected at the European Southern Observatory in Chile.