scholarly journals Pulsations in 66 Oph: Multiperiodicity in He I 6678

2000 ◽  
Vol 175 ◽  
pp. 256-259 ◽  
Author(s):  
M. Floquet ◽  
C. Neiner ◽  
D. Briot ◽  
J. Chauville ◽  
A.M. Hubert ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Line Profile ◽  
Equivalent Width ◽  
Phase Distribution ◽  
Line Profiles ◽  
Short Term ◽  
Spectroscopic Observations

Abstract66 Oph has shown recurrent short-lived outbursts nicely detected from ground-based and space (Hipparcos) photometry.Spectroscopic observations of He I 6678 and Hα lines were performed in June 1997 and June 1998. Search for short-term periodicities was done in He I 6678 line profiles as in equivalent width EW, radial velocity of the line centroid, and V and R components. At least two frequencies were present: ν = 4.0 c/d and ν = 2.2 c/d. The phase distribution of these frequencies over the line profile corresponds in the nrp frame to g-modes with ℓ ~ 3 − 4 and ℓ = 2 respectively.

scholarly journals Spectral variation of BU Tau

2010 ◽  
Vol 6 (S272) ◽  
pp. 380-381
Author(s):  
Kalju Annuk
Keyword(s):  
Radial Velocity ◽  
Line Profile ◽  
Line Intensity ◽  
Equivalent Width ◽  
Spectral Variation ◽  
Spectroscopic Observations

AbstractWe present the preliminary result of our spectroscopic observations covering a period over more than ten years, from 1999 up to 2010. We analyze line profile variations of several lines before the shell phase and during the shell phase. The measured radial velocity, equivalent width and line intensity variations are presented.

scholarly journals A Transient Shock-Wave in the Shell of the Be Star HD 184279

1987 ◽  
Vol 92 ◽  
pp. 95-98
Author(s):  
D. Ballereau ◽  
J. Chauville
Keyword(s):  
Shock Wave ◽  
Radial Velocity ◽  
Emission Spectrum ◽  
Short Term ◽  
Balmer Series ◽  
Spectroscopic Observations ◽  
The Past ◽  
Be Star ◽  
Long Term Variations

HD 184279 (V1294 Aql) has presented in the past an emission spectrum on the first terms of the Balmer series, and shell absorptions on the hydrogen and neutral helium lines. Their variations have been reported by Merrill (1952), Merrill and Lowen (1953) and Svolopoulos (1975). Ballereau and Hubert-Delplace (1982) evidenced long-term V/R variations with an amplitude of ∼100 km s-1. Short-term photometric variations are irregular (Tempesti and Patriarca, 1976), while long-term variations are correlated with radial velocity (RV) of shell lines (Horn et al., 1982). Ballereau and Chauville (in preparation) extended the spectroscopic observations until 1984 and confirmed the pseudo-periodic variations, the last half-period ranging over 3.4 years (April 1, 1980-August 1, 1983).

scholarly journals Structure and Evolution of SV Centauri

1982 ◽  
Vol 69 ◽  
pp. 205-216 ◽  
Author(s):  
H. Drechsel ◽  
J. Rahe ◽  
W. Wargau ◽  
B. Wolf
Keyword(s):  
Time Scale ◽  
Evolutionary Stage ◽  
Line Profiles ◽  
Orbital Elements ◽  
Short Term ◽  
Spectroscopic Observations ◽  
Interaction Processes ◽  
Photometric And Spectroscopic Observations ◽  
Type Contact ◽  
Period Decrease

AbstractOptical photometric and spectroscopic observations of the eclipsing binary SV Cen were used to derive orbital elements and absolute dimensions of the peculiar early-type contact system. UV spectroscopic observations obtained with the IUE satellite yielded the detection of mass loss from the system forming an expanding circumbinary envelope. SV Cen exhibits a non-uniform rate of period decrease, with major variations on a time scale of a few years. The period changes are explained in terms of loss of angular momentum carried away by the ejected matter. Short-term fluctuations of the stellar wind on a time scale of a few hours were found from an analysis of the envelope line profiles of UV resonance lines. A model of the system is derived, and the evolutionary stage and interaction processes are discussed.

scholarly journals A Flower on a WIRE: Asteroseismology of a Massive Star

2002 ◽  
Vol 185 ◽  
pp. 620-623
Author(s):  
J. Cuypers ◽  
C. Aerts ◽  
D. Buzasi ◽  
J. Catanzarite ◽  
T. Conrow ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Line Profile ◽  
Massive Star ◽  
Star Tracker ◽  
Line Profiles ◽  
Velocity Data ◽  
Perfect Agreement ◽  
The One ◽  
Radial Velocity Data ◽  
Profile Study

AbstractRecently it became clear from a line profile study that the β Cephei star β Crucis (Mimosa) is multiperiodic with at least three modes excited. Observations of this star by the star tracker of the WIRE satellite have now confirmed the multiperiodicity in the light variations. A total of 5 million observations covering 17 days was analysed and the three main periods are in perfect agreement with the line profile results. The amplitudes are small (3, 2.7 and 0.6 millimag for the dominant modes), but this is not surprising in view of the mode identifications derived from the line profiles. More periods could still be present, including the one earlier suggested by the radial velocity data.

scholarly journals Investigations of the MnI 539.47 nm and MnI 542.04 nm lines in solar plages

2005 ◽  
pp. 115-121 ◽  
Author(s):  
Istvan Vince ◽  
O. Gopasyuk ◽  
S. Gopasyuk ◽  
Oliver Vince
Keyword(s):  
Line Profile ◽  
Equivalent Width ◽  
Surface Coverage ◽  
Solar Surface ◽  
Activity Cycle ◽  
Full Width ◽  
Half Maximum ◽  
Line Profiles ◽  
Plage Region ◽  
Magnetic Filed

We observed the MnI 539.47 nm and 542.04nm line profiles in the quiet photosphere and plage regions in 1998 and 2001, and measured the full widths at half maximum, equivalent widths and depths of these profiles. The relative changes of the MnI 539.47 nm line parameters, normalized to the values obtained for quiet photosphere, as a function of magnetic field strength in plages is analyzed. We found, for plage region observed in 1998, that both the equivalent width and the depth of the line profile decrease with increasing strength of magnetic filed in plage at a rate of 9x10?4 /Gauss, but the full width at half maximum does not show any significant regular changes. Based on these results, the variations of the MnI 539.47 nm spectral line in solar flux with activity cycle could be explained by the variation of solar surface coverage with plages. For observations in 2001, the equivalent width and the depth of this line profile also decrease with increasing strength of magnetic filed in plage, but there are significant differences in the behavior of line parameters in comparison with the 1998 values. Comparison of changes of the MnI 539.47 nm line parameters with the parameters of the MnI 542.04 nm line in 1998 shows a clear discrepancy between them. On the contrary, in 2001 the full widths at half maximum and the equivalent widths of these two lines behaved in a similar fashion. .

Short Term Variations in the Spectrum of the T Tauri Star DI Cep

1979 ◽  
Vol 46 ◽  
pp. 369-370
Author(s):  
R. Mundt ◽  
U. Bastian
Keyword(s):  
Time Scales ◽  
Time Resolution ◽  
Equivalent Width ◽  
Tauri Star ◽  
Emission Lines ◽  
Short Term ◽  
Spectroscopic Observations ◽  
T Tauri ◽  
Time Variations ◽  
Short Time

AbstractExtended spectroscopic observations of the T Tauri star DI Cep with a time resolution of 10 to 15 minutes have been carried out. On 2 of 6 observing nights the star showed significant variations of the strengths of its emission lines on time scales down to the time resolution of the observations. The most drastic event is shown in Figure 1. The equivalent width of the Hα line increased by a factor of 7 within two hours. Even faster variations, but of smaller amplitude, were observed in the strengths of the Hβ and Till 82 (λ 4572 Å) lines on another night. Obviously strong short time variations are not always present in DI Cep, as in 4 nights no significant variations could be detected.

scholarly journals Multiperiodic Variability and Outbursts of 28 Cygni

2000 ◽  
Vol 175 ◽  
pp. 232-235 ◽  
Author(s):  
S. Tubbesing ◽  
Th. Rivinius ◽  
B. Wolf ◽  
A. Kaufer
Keyword(s):  
Dimensional Analysis ◽  
Line Profile ◽  
Phase Distribution ◽  
Radial Velocities ◽  
Spectral Lines ◽  
Two Dimensional ◽  
Line Profiles ◽  
Constructive Interference ◽  
Mode Beating ◽  
Multi Mode

Abstract28 Cygni was observed during two seasons spectroscopically. The radial velocities of more than 15 spectral lines were measured and searched for periodic variability. Two closely spaced periods were found. A two-dimensional analysis of the line profile variability yielded the same periods and provided the power and phase distribution across the line profiles. An outburst covered by our data coincides with the time of constructive interference of both periods. 28 Cyg is the second case for which outbursts seem to be triggered by multi-mode beating.

scholarly journals Asymmetry of metallic spectral lines in Cepheids

1993 ◽  
Vol 139 ◽  
pp. 375-375
Author(s):  
Michael Albrow ◽  
P.L. Cottrel
Keyword(s):  
High Resolution ◽  
Radial Velocity ◽  
Velocity Curve ◽  
Radial Velocities ◽  
Spectral Lines ◽  
Line Profiles ◽  
Radial Velocity Curve ◽  
Spectroscopic Observations ◽  
The Asymmetry

AbstractA program of high resolution spectroscopic observations of Cepheids has been carried out at Mt John University Observatory for several years. Radial velocities and asymmetries have been measured for selected metallic lines using the method of Wallerstein et al (1992).The line profiles show the largest asymmetry at phases of maximum inward velocity. The asymmetry at phases of maximum outward velocity is smaller and sometimes in the same direction as for the inward velocity maxima. Enhanced asymmetry is also noticed at phases where the bump appears on the radial velocity curve.To date our models are unable to predict such behaviour. It is important that a satisfactory explaination for these observations be found so that the accuracy of Baade-Wesselink radius solutions for such stars can be assessed.

scholarly journals An Analysis of Broad Emission-Line Profiles from HST Data

1997 ◽  
Vol 159 ◽  
pp. 195-196
Author(s):  
Stephanie A. Snedden ◽  
C. Martin Gaskell
Keyword(s):  
Radial Velocity ◽  
Emission Line ◽  
Line Profile ◽  
B Value ◽  
Line Profiles ◽  
Broad Emission ◽  
Blue Wing ◽  
Broad Emission Line

AbstractWe have analyzed the HST FOS spectra of all quasars in the Stirpe (1990) high S/N line-profile sample and studied line-profile ratios as a function of radial velocity. Some quasars show no sign at all of NLR Lyα. We confirm that Hα is narrower than Lyα (after allowance for NLR contributions). The Lyα/Hα ratios in the cores of the broad lines are all close to or slightly less than case B and values predicted by single-cloud photoionization models. The Lyα/Hα ratio is surprisingly high in the blue wing. With only one exception, the ratios are equal to or greater than the case B value. Intrinsic reddening must be very small in most cases. We also briefly discuss other ratios.

scholarly journals Short-term Periodicity in the Pole-on Be Star υ Cyg

2000 ◽  
Vol 175 ◽  
pp. 260-263 ◽  
Author(s):  
M. Floquet ◽  
C. Neiner ◽  
A.M. Hubert ◽  
E. Janot-Pacheco ◽  
N.V. Leister
Keyword(s):  
Radial Velocity ◽  
Short Term ◽  
Spectroscopic Observations ◽  
R Ratio ◽  
Low Degree ◽  
Be Star

AbstractThe pole-on Be star υ Cyg (HD 202904) displayed with Hipparcos photometry a strong long-lived outburst between 1989 and 1993. High S/N spectroscopic observations were obtained in August-September 1998. The photospheric λ6678 line is strongly perturbed by variable outer V and R emission components and is itself highly variable.All the studied quantities (profiles, EW, radial velocity of the line centroid, V and R emission components, V/R ratio) are dominated by ν = 1.5 c/d frequency. The first harmonic (ν = 3.0 c/d) is also detected in the central part of the profile. In the nrp frame, this pair of frequencies corresponds to a low degree sectorial g-mode l = |m| = 2. Moreover mid-term variations are superimposed to short ones.

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