scholarly journals A Study of Ultraviolet Spectra of Delta Sagittae

1992 ◽  
Vol 151 ◽  
pp. 273-275
Author(s):  
A. Akalin ◽  
S. Engin
Keyword(s):  
High Resolution ◽  
Radial Velocity ◽  
Orbital Motion ◽  
Velocity Curve ◽  
Velocity Variation ◽  
High Resolution Spectrum ◽  
Radial Velocity Curve ◽  
Radial Velocity Variation ◽  
Component Matching ◽  
Absorption Features

High resolution spectrum of the VV Cephei type star δ Sge (M2 II + A0 V) observed with the IUE satellite between 1979–1985 have been analysed. The radial velocity curves of non blended absorption features have been formed. Observed radial velocities are compared with the theoretical radial velocity curve due to orbital motion. We found that observed radial velocity variation is the resultant of radial velocity of hotter component and wind velocity around this star. The wind is perturbed by hotter component. Matching the UV continuum fluxes obtained from IUE high resolution spectra to fluxes of Kurucz model atmospheres yields Te=11000±500 °K. Thus the spectral type of hot component was found as A0.

Can Osawa'S Star HD 221568 be an Oblique Rotator?

1976 ◽  
Vol 32 ◽  
pp. 603-610
Author(s):  
Keiichi Kodaira
Keyword(s):  
Radial Velocity ◽  
Line Intensity ◽  
Orbital Motion ◽  
Intensity Variation ◽  
Velocity Curve ◽  
Velocity Variation ◽  
Velocity Data ◽  
Rotator Model ◽  
Oblique Rotator ◽  
Radial Velocity Data

SummaryRadial velocity data of HD 221568 are critically reexamined. The revised data lead to a velocity curve essentially the same as obtained by Kodaira (1967). It is shown that the velocity variation of HD 221568 could be attributed to orbital motion, if an oblique rotator model is to be assumed for the cause of line-intensity variation.

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 Methods of the Long-term Radial-Velocity Variation Removal and their Application to Detect Duplicity of Several Be Stars

2011 ◽  
Vol 7 (S282) ◽  
pp. 319-320
Author(s):  
J. Nemravová ◽  
P. Harmanec ◽  
P. Koubský ◽  
A. Miroshnichenko
Keyword(s):  
Radial Velocity ◽  
Binary Stars ◽  
Orbital Motion ◽  
Continuous Functions ◽  
Velocity Variation ◽  
Be Stars ◽  
The Third ◽  
Radial Velocity Variation ◽  
Velocity Variations

AbstractThere are several types of binary stars which show non-periodical radial velocity variations with the amplitude larger than those connected with the orbital motion. The non-periodical changes have to be removed in order to study the orbital ones. We propose three removal techniques, two of which are based on the trend modeling with continuous functions and the third one that takes the orbital motion into account.

scholarly journals XO-2b: a Prograde Planet with Negligible Eccentricity and an Additional Radial Velocity Variation

2011 ◽  
Vol 63 (6) ◽  
pp. L67-L71 ◽  
Author(s):  
Norio Narita ◽  
Teruyuki Hirano ◽  
Bun'ei Sato ◽  
Hiroki Harakawa ◽  
Akihiko Fukui ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Velocity Variation ◽  
Radial Velocity Variation

scholarly journals WASP-4 transit timing variation from a comprehensive set of 129 transits

2020 ◽  
Vol 496 (1) ◽  
pp. L11-L15 ◽  
Author(s):  
R V Baluev ◽  
E N Sokov ◽  
S Hoyer ◽  
C Huitson ◽  
José A R S da Silva ◽  
...  
Keyword(s):  
Conservative Treatment ◽  
Radial Velocity ◽  
Decay Rate ◽  
High Accuracy ◽  
Light Curves ◽  
Velocity Variation ◽  
Radial Acceleration ◽  
Radial Velocity Variation ◽  
Non Linear ◽  
Doppler Data

ABSTRACT We homogeneously reanalyse 124 transit light curves for the WASP-4 b hot Jupiter. This set involved new observations secured in 2019 and nearly all observations mentioned in the literature, including high-accuracy GEMINI/GMOS transmission spectroscopy of 2011–2014 and TESS observations of 2018. The analysis confirmed a non-linear transit timing variation (TTV) trend with $P/|\dot{P}|\sim \hbox{17-30}$ Myr (1σ range), implying only half of the initial decay rate estimation. The trend significance is at least 3.4σ in the aggressively conservative treatment. Possible radial acceleration due to unseen companions is not revealed in Doppler data covering seven years 2007–2014, and radial acceleration of −15 m s−1 yr−1 reported in a recent preprint by another team is not confirmed. If present, it is a very non-linear radial velocity variation. Assuming that the entire TTV is tidal in nature, the tidal quality factor $Q_\star ^{\prime }\sim \hbox{(4.5-8.5)}\times 10^4$ does not reveal a convincing disagreement with available theory predictions.

scholarly journals The Radial Velocity Curve of V652 Her (BD+13°3224)

1985 ◽  
Vol 87 ◽  
pp. 109-115
Author(s):  
P.W. Hill ◽  
C.S. Jeffery
Keyword(s):  
Radial Velocity ◽  
Time Resolution ◽  
High Frequency ◽  
Velocity Curve ◽  
Velocity Data ◽  
Effective Surface ◽  
Radial Velocity Curve ◽  
Minimum Radius ◽  
Helium Star ◽  
Radial Velocity Data

AbstractNew radial velocity data for the pulsating extreme helium star V652 Her (BD+13°3224) have been obtained with a time resolution of 100 s. High frequency structure in the radial velocity curve is detected, and a comparison with previous data suggests that the detailed shape of the velocity curve is variable. The data imply that the effective surface gravity must increase by a factor of 4 at minimum radius.

The radial-velocity curve of V1010 Ophiuchi - Orbital elements and the rotational disturbance

1988 ◽  
Vol 100 ◽  
pp. 371 ◽  
Author(s):  
Thaddeus F. Worek ◽  
Eugene R. Zizka ◽  
Merle W. King ◽  
Joost H. Kiewiet de Jonge
Keyword(s):  
Radial Velocity ◽  
Velocity Curve ◽  
Orbital Elements ◽  
Radial Velocity Curve
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