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 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 Rapid spectroscopic and photometric variability in the Be star Alpha Eridani

1994 ◽  
Vol 162 ◽  
pp. 106-107
Author(s):  
N.V. Leister ◽  
E. Janot-Pacheco ◽  
M.T.C. Buck ◽  
M.P. Dias ◽  
A.M. Hubert ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Time Scale ◽  
Preliminary Report ◽  
Photometric Variability ◽  
Spectroscopic Observations ◽  
Photometric And Spectroscopic Observations ◽  
Be Star ◽  
Spotted Star ◽  
Activity Cycles ◽  
Comprehensive Study

We present here a preliminary report on the analysis of simultaneous photometric and spectroscopic observations of the Be star α Eri, taken during 1992 at the Laboratório Nacional de Astrofísica. α Eri (Archenar, HR472, HD10144, B3–4 III-IV) is the brightest Be star in the sky. It shows activity cycles in a time scale of a few years. Balona et al. (1987) presented a comprehensive study of the star based on photometric and spectroscopic observations. They found a periodicity of 1.26 days in both radial velocity and light variations and argued that a spotted star rotating at this period is the simplest working model that explains the observations.

Models of Cataclysmic Variables from Photometric and Spectroscopic Data

1979 ◽  
Vol 46 ◽  
pp. 65-74 ◽  
Author(s):  
A.C. Fabian ◽  
J.E. Pringle ◽  
J.A.J. Whelan ◽  
J.A. Bailey
Keyword(s):  
Spectroscopic Data ◽  
Cataclysmic Variables ◽  
System Parameters ◽  
Dwarf Nova ◽  
Spectroscopic Observations ◽  
Photometric And Spectroscopic Observations

Abstract.Recent photometric and spectroscopic observations of the dwarf nova system Z Cha are discussed. Methods for constraining the system parameters are applied and the disc emissivity is deduced as a function of radius. Indications are found that the disc shrinks in size with increasing time after outburst.

scholarly journals An attempt of seismic modelling of β Cephei stars in NGC 6910

2014 ◽  
Vol 9 (S307) ◽  
pp. 222-223
Author(s):  
D. Moździerski ◽  
Z. Kołaczkowski ◽  
E. Zahajkiewicz
Keyword(s):  
Seismic Modeling ◽  
Preliminary Results ◽  
Spectroscopic Observations ◽  
Seismic Modelling ◽  
Photometric And Spectroscopic Observations

AbstractWe present preliminary results of seismic modeling of β Cephei-type stars in NGC 6910 based on simultaneous photometric and spectroscopic observations carried out in 2013 in Białków (photometry) and Apache Point (spectroscopy) observatories.

scholarly journals V 3903 Sagitarii: A Main-Sequence (07V+09V) Detached Eclipsing Binary

1993 ◽  
Vol 137 ◽  
pp. 371-373
Author(s):  
L.P.R. Vaz ◽  
N.C.S. Cunha ◽  
E.F. Vieira ◽  
M.L.M. Myrrha
Keyword(s):  
Main Sequence ◽  
Eclipsing Binary ◽  
Spectroscopic Observations ◽  
Photometric And Spectroscopic Observations ◽  
Absolute Dimensions

AbstractPhotometric and spectroscopic observations of V3903 Sgr are analyzed, and absolute dimensions (masses and radii) are determined to a precision better then 3%.

scholarly journals New photometric and spectroscopic observations of the Seyfert galaxy Mrk 315

2005 ◽  
Vol 360 (1) ◽  
pp. 253-271 ◽  
Author(s):  
S. Ciroi ◽  
V. L. Afanasiev ◽  
A. V. Moiseev ◽  
V. Botte ◽  
F. Di Mille ◽  
...  
Keyword(s):  
Seyfert Galaxy ◽  
Spectroscopic Observations ◽  
Photometric And Spectroscopic Observations

scholarly journals Precise Point Positioning for TAI Computation

2008 ◽  
Vol 2008 ◽  
pp. 1-8 ◽  
Author(s):  
Gérard Petit ◽  
Zhiheng Jiang
Keyword(s):  
Time Scale ◽  
Carrier Phase ◽  
Precise Point Positioning ◽  
Dual Frequency ◽  
Time Transfer ◽  
Short Term ◽  
Reference Time ◽  
Local Clock ◽  
Point Positioning ◽  
Simple Difference

We discuss the use of some new time transfer techniques for computing TAI time links. Precise point positioning (PPP) uses GPS dual frequency carrier phase and code measurements to compute the link between a local clock and a reference time scale with the precision of the carrier phase and the accuracy of the code. The time link between any two stations can then be computed by a simple difference. We show that this technique is well adapted and has better short-term stability than other techniques used in TAI. We present a method of combining PPP and two-way time transfer that takes advantage of the qualities of each technique, and shows that it would bring significant improvement to TAI links.

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