scholarly journals Radial Velocity Observations of Binary Stars

1983 ◽  
Vol 62 ◽  
pp. 93-103
Author(s):  
C. D. Scarfe
Keyword(s):  
Radial Velocity ◽  
Binary Stars ◽  
Velocity Measurement ◽  
Cross Correlation ◽  
Radial Velocities ◽  
Measuring Instruments ◽  
Great Stability ◽  
Visual Binary Stars ◽  
Radial Velocity Measurement

AbstractThis review considers three main areas, leaving several others to be discussed in more detail in the contributed papers of this session.1.The need for spectrographs and measuring instruments of great stability for long-term projects such as radial velocity observations of visual binary stars.2.The use of cross-correlation devices, both analog (radial velocity scanners) and digital, for radial velocity measurement.3.The use of comparison spectra impressed directly onto the starlight and of polarisation instruments as means to very precise radial velocities.

scholarly journals Long-Term Coudé Radial-Velocity Studies With a 1.2-m Telescope

2001 ◽  
Vol 183 ◽  
pp. 283-288
Author(s):  
C.D. Scarfe
Keyword(s):  
Radial Velocity ◽  
Binary Stars ◽  
Star System ◽  
Standard Star ◽  
Stellar Spectra ◽  
Multiple Stars ◽  
Binary And Multiple Stars ◽  
Selection Of

AbstractI have used the 1.2-m telescope and coudé spectrograph of the Dominion Astrophysical Observatory for more than 30 years in a program of radial-velocity observations of binary stars. The program was begun with photographic plates as detectors, but for 20 years the primary detector has been the radial-velocity scanner, which cross-correlates stellar spectra with an artificial mask.Since some of the binaries under observation have periods of several years, the instrument’s stability is an important consideration. I have therefore been obliged to observe standard stars and asteroids to check its performance. These observations are of relevance to efforts to improve the IAU standard star system.I will describe the telescope, spectrograph and scanner, and will briefly discuss some of the results obtained for a selection of binary and multiple stars.

scholarly journals Precise Radial Velocities

1992 ◽  
Vol 135 ◽  
pp. 67-72
Author(s):  
Gordon A.H. Walker
Keyword(s):  
Radial Velocity ◽  
Radial Velocities ◽  
Velocity Variations ◽  
Low Amplitude

AbstractCurrent techniques for the detection of long-term, low-amplitude (<50 m s−1), radial velocity variations are briefly reviewed together with some of their most successful programs. In the era of 8- to 10-m telescopes we must strive for a precision of < 1ms−1.

scholarly journals TODCOR: A Two-Dimensional Correlation of a Composite Spectrum to Derive the Radial Velocities of its Components

1992 ◽  
Vol 135 ◽  
pp. 164-166
Author(s):  
Tsevi Mazeh ◽  
Shay Zucker
Keyword(s):  
Radial Velocity ◽  
Cross Correlation ◽  
Radial Velocities ◽  
Two Dimensional ◽  
One Dimensional ◽  
Independent Variables ◽  
Doppler Shifts ◽  
Correlation Algorithm ◽  
Potential Difficulty ◽  
The One

Cross correlation is a frequently used technique to obtain the Doppler shifts of digitized celestial spectra. This method, suggested by Tonry & Davis (1979), cross correlates the observed spectrum against an assumed template, and obtains the stellar radial velocity by the location of the correlation maximum (Wyatt 1985). The technique finds the correct radial velocity even for extremely low S/N spectra.Spectra composed of two components present a potential difficulty to this technique. The cross correlation of these spectra usually displays a double peak which can not be resolved whenever the relative velocity of the two components is small. To overcome this difficulty, we developed TODCOR — a new TwO-Dimensional CORrelation algorithm which can simultaneously derive the Doppler shifts of the two components.TODCOR assumes that the observed spectrum is a combination of two known spectra with unknown shifts. Following the one-dimensional technique, the algorithm calculates the correlation of the observed spectrum against a set of combinations of two templates, with all possible shifts. The correlation, thus, is a two-dimensional function, whose two independent variables are the radial velocities of the two components. The location of the maximum of this function corresponds to the actual Doppler shifts of the two components.

scholarly journals Photon-weighted barycentric correction and its importance for precise radial velocities

2019 ◽  
Vol 489 (2) ◽  
pp. 2395-2402 ◽  
Author(s):  
René Tronsgaard ◽  
Lars A Buchhave ◽  
Jason T Wright ◽  
Jason D Eastman ◽  
Ryan T Blackman
Keyword(s):  
Velocity Measurement ◽  
Correction Term ◽  
Systematic Errors ◽  
Order Effect ◽  
Second Order ◽  
Radial Velocities ◽  
Similar Measure ◽  
Radial Velocity Measurement ◽  
Existing Data ◽  
Flux Curve

ABSTRACT When applying the barycentric correction to a precise radial velocity measurement, it is common practice to calculate its value only at the photon-weighted mid-point time of the observation instead of integrating over the entire exposure. However, since the barycentric correction does not change linearly with time, this leads to systematic errors in the derived radial velocities. The typical magnitude of this second-order effect is of order 10 cm s−1, but it depends on several parameters, e.g. the latitude of the observatory, the position of the target on the sky, and the exposure time. We show that there are realistic observing scenarios, where the errors can amount to more than 1 m s−1. We therefore recommend that instruments operating in this regime always record and store the exposure meter flux curve (or a similar measure) to be used as photon-weights for the barycentric correction. In existing data, if the flux curve is no longer available, we argue that second-order errors in the barycentric correction can be mitigated by adding a correction term assuming constant flux.

Study on a multi-delay spectral interferometry for stellar radial velocity measurement

2014 ◽  
Author(s):  
Kai Zhang ◽  
Haijiao Jiang ◽  
Jin Tang ◽  
Hangxin Ji ◽  
Yongtian Zhu ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Velocity Measurement ◽  
Spectral Interferometry ◽  
Radial Velocity Measurement
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