Spectroscopic Period Research Articles

THE SEMI-REGULAR VARIABLE FS COMAE--EVIDENCE FOR RADIAL OSCILLATIONS

ABSTRACT We present newly obtained radial-velocity measurements of the semi-regular variable FS Comae, together with available photoelectric data and visual brightness estimates. Both the light variations in the V band and the radial velocities show a similar periodicity of about 55 days, with a phase lag of approximately 40 days between the two. These observations strongly suggest radial pulsation as the mechanism driving the variations. There is evidence that both the photometric period and the spectroscopic period are variable over long timescales.

DETECTION OF HIGH-DEGREE NONRADIAL PULSATIONS IN GAMMA BOOTIS

ABSTRACT The line-profile variations of the rapidly rotating delta Scuti star gamma Boo can be explained by high-degree (|m| /= 10) nonradial pulsations (NRPs) with an apparent period of Delta t /= 0.047 days. This same period was derived from two data sets taken three months apart where-in the amplitude increased by 30%. Such high-degree NRP cannot explain the apparent reversals previously observed (Auvergne, Le Contel & Baglin 1979) for this star in the cores of the hydrogen Balmer lines and CaII K line. Our radial-velocity variations can be reconciled with their 0.25 day spectroscopic period if an amplitude of 1 km s-1 is adopted, an order of magnitude less than previous measurements. We demonstrate that the presence of line-profile variations from high-degree modes probably limits the accuracy of radial-velocity measurements and may appear as bumps in the radial-velocity curve.

The spectroscopic period of the cataclysmic system AM CVn

We present some preliminary results of a time-resolved spectroscopic study of the peculiar cataclysmic system AM CVn. The analysis of Hei lines profile variability, suggests the existence of a 1051 s periodicity. This is one of the known photometric periods, candidate to be the orbital period of the system, or the rotational period of the primary.

V795 Herculis (PG 1711+336) - A new intermediate polar in the period gap

New photometric and spectroscopic observations of the nova-like variable V795 Her are reported. A period of 0.1164865(4) days for the light curve variation, and a 0.1082648(3) day period with an amplitude of 70 + or - 20 km/s for the radial velocity variation were established, which leads to the conclusion that the photometric and spectroscopic periods are different. It is argued that V795 Her is an intermediate polar and that one period is the orbital, identified as spectroscopic, and the other is associated with the rotation of the magnetized, accreting white dwarf. It is suggested that the photometric period is the beat period between the orbital period and the rotation period of the white dwarf. The orbital period of V795 Her is near the middle of the gap in the orbital period distribution for cataclysmic variables. Two possibilities for the evolutionary state of V795 Her are examined. 33 refs.

CP Puppis: Another V1500 Cyg?

As first pointed out by Warner (1985), the overall properties of CP Pup and V1500 Cyg are very similar: both were very fast, very large amplitude novae with ~ 0.3 mag photometric humps at roughly the orbital period. Neither variation is strictly periodic (Patterson 1979; Warner 1985). Variable circular polarization (with period slightly different from the orbital period) has been found in V1500 Cyg showing that its white dwarf is strongly magnetic and has broken synchronism with the secondary star (Stockman, Schmidt & Lamb 1988). In contrast, no circular polarization has been found in CP Pup. Nonetheless, does the slight difference between the photometric and spectroscopic periods indicate it is also a magnetic system (Warner 1985; Bianchini et al. 1985a)?New photometric and spectroscopic data for CP Pup are reported which resolve the aliases and confusion in the periods found by Bianchini et al. (1985a,b), Warner (1985) and Duerbeck et al. (1987) and allow an examination of the evidence for its magnetic nature.

H0534 - 581: A new intermediate polar?

view Abstract Citations (23) References (47) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS H0534-581: A New Intermediate Polar? Buckley, D. A. H. ; Tuohy, I. R. Abstract Optical spectroscopic and photometric observations of the hard X-ray-emitting HEAO 1 cataclysmic variable, H0534 - 581 are discussed. From the analysis of Exosat time series data, spectroscopic periods at 6 and 2.1 hr are identified as the orbital and white dwarf spin periods, respectively. The results suggest that H0534 - 581 is a member of the intermediate polar (DQ Herculis) class of magnetic cataclysmic variables. Publication: The Astrophysical Journal Pub Date: January 1990 DOI: 10.1086/168314 Bibcode: 1990ApJ...349..296B Keywords: Cataclysmic Variables; Magnetic Stars; Stellar Spectrophotometry; White Dwarf Stars; X Ray Binaries; Angular Velocity; Emission Spectra; Light (Visible Radiation); Line Spectra; Astrophysics; STARS: BINARIES; STARS: DWARF NOVAE; STARS: INDIVIDUAL ALPHANUMERIC: H0534-581; STARS: MAGNETIC; X-RAYS: BINARIES full text sources ADS | data products SIMBAD (12)

Analysis of the photometric and spectroscopic period of the symbiotic star AG Pegasi with consequences for the model

Analysis of the photometric and spectroscopic period of the symbiotic star AG Pegasi with consequences for the model

The constancy of the gamma velocity of AC211 ( = 4U2127 + 11 in M15)

We find that the parameters of the radial velocity curve of AC211, the optical counterpart of the M15 X-ray source (4U2127 + 11), have not changed significantly between observations spaced approximately 1 yr apart, thus confirming that this object shows a large blueshift with respect to the cluster. The constancy of the γ velocity is consistent with the dynamical explanation of Naylor et al. but allows us to rule out, with a high degree of confidence, the ‘SU UMa’ explanation of the velocity shift, suggested by the same authors. We also determine a more accurate spectroscopic period than previously published, of 8.46±0.15 hr.

The spectroscopic period of the Cepheid SU Cassiopeiae

AbstractThe spectroscopic period of the short periodic Cepheid SU Cas was determined from the radial velocity measurements by ABT, GIEREN and HÄUPL. The calculated period is 1.949312 days. Radial velocity differences between measurements by GIEREN and HÄUPL are explained as velocity zero point of the used spectrographs. The zero point of the Tautenburg Coudé spectrograph was determined by measuring the radial velocity standard star ϵ Leo. The difference to the standard value was ‐0.7 km/s. No significant differences are found between the spectroscopic period and light curve of SU Cas in the last 35 years.

Spectroscopic Orbit of the Eclipsing Symbiotic Star CH Cyg

Mikołajewski et al.(1987) quoted convincing arguments that CH Cygni is eclipsing binary system:1.Photometric minima in U light were separated by 57004÷5780 days which is very close to the spectroscopic period (P=5750±250d) found by Yamashita and Maehara (1979).2.Variations of Hβ and Hγ profiles during both minima can be succesfully interpreted as an eclipse of a rotating disk or envelope from which these profiles originate (see also Fernie et al.,1986).3.The flickering activity was absent during the 1985 minimum while observed before and after the minimum.4.Only forbidden lines were unaffected by the minimum. Recently, additional arguments for the eclipsing nature of CH Cygni have been found:5.Deep minimum in the IUE integrated flux was coincided with the minimum detected in U light (Mikołajewska et al., 1987a).6.Changes of Balmer decrement and Balmer continuum emission measure suggest a presence of relatively small dense region occulted during the minimum and extended low density region coinciding with the radio jets (Mikołajewska et al., 1987b).7.Radial velocity of the jet spatially resolved by Solf (1987) in the [OIII]5007 line suggests the jet is practically perpendicular to the line of sight.

Some Important Results From Two Photometric Campaigns on Short Term Variability in Be Stars

In 1983 and 1984 a programme of UBV observations was carried out to set up a network of standard stars, identify short term variables, and analyse the variability of the 86 bright (V ≳ 6.5) southern (δ < -20°) Be stars.The timing of the observations was designed specifically to reveal short term variability. Each group of Be and comparison stars was observed at least four times. Where possible, the first two sets of observations were made on one night and the next two sets on the next night (and sometimes a fifth set of observations was also made). Eleven Be stars were identified as possible short or intermediate term variables (Stagg, in preparation). These included the Be star 28 ω CMa, whose V and B-V (but not U-B) variations were consistent with the spectroscopic period of 1.37 days found by Baade (1982).

The orbit of the speckle and double-lined spectroscopic binary CHI Draconis

view Abstract Citations (19) References (28) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Orbit of the Speckle and Double-Lined Spectroscopic Binary Chi Draconis Tomkin, Jocelyn ; McAlister, Harold A. ; Hartkopf, William I. ; Fekel, Francis C. Abstract The authors have used high-resolution, high-signal-to-noise-ratio Reticon and CCD observations of the red and near-infrared spectrum of this double-line spectroscopic binary to measure the first extensive set of secondary velocities and thereby determine a revised spectroscopic mass ratio M1/M2 = 1.38. Analysis of new, and previously published, speckle observations provides the apparent orbit, which, for the first time, can be determined independently of the spectroscopic orbit of the primary. The authors do adopt for the final visual orbit the spectroscopic period, eccentricity, and epoch of periastron passage, which benefit from the much longer time base of the spectroscopic observations. The analysis of the speckle observations leads to the elements a = 0arcsec.122 and i = 74°.9. These results provide new masses and luminosities for the components: M1 = 1.03 M_sun;, L1 = 1.86 L_sun;, M2 = 0.75 M_sun;, and L2 = 0.29 L_sun;. The derived parameters of the components are compared with theoretical isochrones of a slightly metal-poor star. Best agreement is found for an age of 8 billion years. Thus, χ Dra is one of the few systems older than the Sun whose fundamental parameters have been accurately determined, providing a benchmark for evolutionary theory. Publication: The Astronomical Journal Pub Date: May 1987 DOI: 10.1086/114404 Bibcode: 1987AJ.....93.1236T Keywords: Binary Stars; Speckle Interferometry; Stellar Orbits; Stellar Spectrophotometry; Metallicity; Stellar Luminosity; Stellar Mass; Astrophysics; STARS: BINARIES full text sources ADS | data products SIMBAD (1)

Photometry of TT Arietis

AbstractAn analysis of data spanning 24 years shows that a secondary 20m periodicity is a persistent feature in photometric observations of TT Ari. This period decreases from 27m in 1961 to 17m in 1985. The 4d beat period of photometric and spectroscopic periods is also apparent in observations of 1966.

Orbital studies of cataclysmic binaries. II - Three objects from the Palomar-Green sample

view Abstract Citations (55) References (33) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Orbital studies of cataclysmic binaries. II. Three objects from the Palomar-Green sample. Thorstensen, J. R. Abstract I obtained radial-velocity spectra of PG 0834 + 488, PG 1003 + 678 = CH UMa, and PG 1711 + 336 = V795 Her to determine their orbital periods. PG 0834 + 488 has an apparently normal dwarf-nova type spectrum, and its orbital period is here found to be 6.4 hr with no cycle-count ambigu- ity. The present data show no visible absorption from a secondary star. PG 1003 + 678 = CH UMa most likely has a period of 8.3 hr, which is an alias of the preliminary period of 12.5 hr announced by Thorstensen (1985); the 12.5 hr period remains possible. It shows absorption features in its spectrum characteristic of a late-type secondary star, and these features appear to have velocities in antiphase to the emission lines. The velocity amplitude is small and the lines narrow, suggesting a low inclination. PG 1711 + 336 = V795 Her has a most likely period of 14.8 hr, unusually long for a cataclysmic binary; because of the weakness of the emission lines, some doubt remains about the period. The 2.75 hr photometric period determined by Baidak et al. (1985) is not indicated in the velocities. The emission lines are weak and the flux distribution very blue. The object is evidently a nova-like variable in a perpetual high state. if the photometric and spectroscopic periods are both correct, it may be a very slow DQ Her star as well. Publication: The Astronomical Journal Pub Date: April 1986 DOI: 10.1086/114070 Bibcode: 1986AJ.....91..940T Keywords: Cataclysmic Variables; Orbit Calculation; Radial Velocity; Stellar Motions; Stellar Orbits; Stellar Spectra; Absorption Spectra; Companion Stars; Emission Spectra; Late Stars; Wavelengths; Astrophysics full text sources ADS | data products SIMBAD (7) Related Materials (1) Part 1: 1985AJ.....90.2082T

THE PHOTOMETRIC VARIABILITY OF LAMBDA ERIDANI.

ABSTRACT Photoelectric uvby and UBV observations of the Be star λ Eri have been obtained during several seasons. Although the observations are not well suited to period analysis, they are consistent with the spectroscopic period of 0d.701538. The amplitude ranges (in b) from 0m.01 to 0m.08, and on one occasion, was observed to change from the minimum value to the maximum value in only two days. The season-to-season variations are 0m.05 (in b) or less. An understanding of the relationship between the photometric variations and the other variations in this star will require systematic, long-term, coordinated observations.

THE TWO PERIODS OF TT ARIETIS.

ABSTRACT To clarify the spectroscopic period and demonstrate that the spectroscopic and photometric periods are distinct, velocities of the cataclysmic variable TT Ari in its high and intermediate photometric states are obtained. Evidence for periodicity is found near the period of Cowley et al. (1975) in both the high-state and intermediate-state velocities and in a reanalysis of the Cowley et al. velocities no evidence is found for periodicity near the photometric period. Since no single period fits all the data well and since the original Cowley et al. period fits all the high-state data quite well, it is shown that the velocities change phase between the high and the intermediate states. Results indicate that the intermediate-state velocities lag the high-state velocities by 0.28 of a cycle and that in the high-state data, the gamma velocities tend to be systematically lower for the high-order Balmer lines.

Spectroscopy of V711 Tauri (= HR 1099) - Fundamental properties and evidence for starspots

view Abstract Citations (113) References (49) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Spectroscopy of V711 Tauri (= HR 1099) : fundamental properties and evidence for starspots. Fekel, F. C., Jr. Abstract New orbital elements have been determined for the bright RS CVn-type system V711 Tau. The spectroscopic period has been refined to 2.83774 d + or - 0.00001 d. The eccentricity is determined to be 0.014 + or - 0.009, and the inclination of the system is 33 deg + or - 2 deg. The masses, radii, and equatorial rotational velocities for each component are stated.Evolutionary models suggest that mass transfer may begin in 70 to 80 million years. High SNR Reticon observations at red wavelengths show substantial differences in rotational velocity and line strength between the two components, as well as asymmetries in all absorption lines of the more massive, active, cooler star. These asymmetries are correlated with photometric variations and move across the line profiles with time. They are the result of starspot regions rotating in and out of view. Publication: The Astrophysical Journal Pub Date: May 1983 DOI: 10.1086/160952 Bibcode: 1983ApJ...268..274F Keywords: Binary Stars; Orbital Elements; Starspots; Stellar Rotation; Stellar Spectra; Variable Stars; Absorption Spectra; Angular Velocity; H Lines; K Lines; Radial Velocity; Spectral Line Width; Stellar Evolution; Stellar Magnitude; Stellar Mass; Astrophysics full text sources ADS | data products SIMBAD (1)

A PRELIMINARY ORBIT FOR HR 2577 : A K + BE BINARY SYSTEM.

ABSTRACT A spectroscopic period of 58 years has been found for the K2 II + B3 IVe composite system HR 2577 (HD 50820). Preliminary orbital elements were calculated for this double-lined pair, giving equal masses for the two stars. The B star is seen to undergo secular changes in the appearance of its Balmer line emission which seem to be unrelated to the binary motion. It is predicted that the system may be capable of being resolved by the technique of speckle interferometry.

An Unusually Stable and Short Spectroscopic Period of the Be Star 28 CMa

Spectroscopic (1970: ESO, 12 Å/mm, 6 spectra kindly put at my disposal by Prof. A. Van Hoof; 1976: ESO, 12 Å/mm; 1977: Calar Alto Observatory, 42 Å/mm; 1979: ESO, 12 Å/mm) and photometric (1976: ESO and Cerro Tololo, Hβ, uvby) observations of 28 CMa (B2-3 IV-Ve; 3.52 < mV < 4.18, irregular variations on the time scale of months or years reported; vrot = 80 km/s) revealed a very complex variability. All observed individual types of variations are known from at least a few other Be stars. In 28 CMa, however, for the first time a highly significant correlation between the various variations is established by a stable common period. The period is 1.365 days which seems to be the shortest stable period presently known of any Be star. There is no indication that the star's behaviour changed between 1970 and 1979. Only the equivalent widths of the emission lines increased noticeably.

Spectroscopy of 2A 0526-328 - A triple periodic cataclysmic variable

view Abstract Citations (55) References (8) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Spectroscopy of 2A 0526-328 : a triple periodic cataclysmic variable. Hutchings, J. B. ; Crampton, D. ; Cowley, A. P. ; Thorstensen, J. R. ; Charles, P. A. Abstract The cataclysmic variable X-ray binary 2A 0526-328 has a spectroscopic (orbital) period of 0.228600 days, a photometric (rotation) period of 0.21631 days, and a beat (photometric) period of 4.024 days. Radial velocity behavior is complex, suggesting orbital motions, a disk hot spot, and a spiraling gas stream. Emission line variations are large and not generally periodic. The system is discussed in terms of a nonsynchronously rotating white dwarf of the DQ Her type. The system presents several unique phenomena for this type of binary. Publication: The Astrophysical Journal Pub Date: October 1981 DOI: 10.1086/159329 Bibcode: 1981ApJ...249..680H Keywords: Binary Stars; Stellar Spectrophotometry; Variable Stars; X Ray Sources; Emission Spectra; Gas Streams; Helium; Hydrogen; Light Curve; Line Spectra; Radial Velocity; Stellar Rotation; X Ray Spectra; Astrophysics full text sources ADS | data products SIMBAD (4)