scholarly journals Precise Radial-velocity Measurements with a Cassegrain Spectrograph, II: Radial-velocity Determination and Applications

1999 ◽  
Vol 170 ◽  
pp. 68-72 ◽  
Author(s):  
I. V. Ilyin ◽  
R. Duemmler
Keyword(s):  
Radial Velocity ◽  
Data Reduction ◽  
High Accuracy ◽  
Radial Velocities ◽  
Velocity Measurements ◽  
Echelle Spectrograph ◽  
The Stability ◽  
Stability Issues

AbstractWe present our measurements of radial velocities of two stars suspected to have a substellar companion by using observations made with a cassegrain échelle spectrograph. The stability issues and details of the data reduction are discussed in Ilyin & Duemmler (paper I, these proceedings). The results obtained here show that relatively high accuracy of radial velocity determinations is also attainable for cassegrain spectrographs.

scholarly journals Precise Radial Velocity Measurements with a Cassegrain Spectrograph, I: Wavelength calibration

1999 ◽  
Vol 170 ◽  
pp. 63-67
Author(s):  
I. V. Ilyin ◽  
R. Duemmler
Keyword(s):  
High Resolution ◽  
Radial Velocity ◽  
Cross Correlation ◽  
Time Dependent ◽  
Instrumental Effects ◽  
Velocity Measurements ◽  
Echelle Spectrograph ◽  
Optical Telescope ◽  
La Palma ◽  
Observational Strategy

AbstractWe briefly describe the instrumental effects which affect the accuracy of the radial velocity measurements. We have implemented several methods to correct for the instability effects and improve the accuracy of the measurements. These include modifications of the observational strategy and a time-dependent wavelength solution as well as a discussion of the error of the offset from cross-correlation. These methods are applied to observations obtained with the high resolution échelle spectrograph SOFIN mounted at the Cassegrain focus of the alt-azimuth 2.56-m Nordic Optical Telescope, La Palma, Canary Islands.

scholarly journals The fiber-fed spectrograph, a tool to detect planets

1999 ◽  
Vol 170 ◽  
pp. 13-21 ◽  
Author(s):  
D. Queloz ◽  
M. Casse ◽  
M. Mayor
Keyword(s):  
Radial Velocity ◽  
Precision Measurements ◽  
Velocity Measurements ◽  
Calibration Technique ◽  
The Stability ◽  
Very High

AbstractThe use of fibers to feed spectrographs is a very efficient way to increase the precision of radial velocity measurements. It has already proved to be successful with the very first detection by the ELODIE fiber-fed spectrograph of the planet orbiting the star 51 Peg. The basic key properties of fibers in the very high radial velocity precision measurements context are described in this review. The ELODIE spectrograph is used to illustrate the thorium simultaneous calibration technique. The use and the effects of a double-scrambler to increase the stability of the slit illumination are also discussed.

scholarly journals The empirical period-radius relation for pulsating stars: a synthesis based on photometric and radial velocity measurements

1986 ◽  
Vol 118 ◽  
pp. 273-274
Author(s):  
G. Burki
Keyword(s):  
Radial Velocity ◽  
Stellar Evolution ◽  
Variable Stars ◽  
Radial Velocities ◽  
Velocity Measurements ◽  
Pulsating Stars ◽  
Powerful Test ◽  
The Mean

The relation existing between the radius and the period for the pulsating stars of a given class constitutes a powerful test for the theory of stellar evolution and for the identification of the pulsation modes. In recent years, several authors have determined the mean radius of a lot of pulsating stars of various classes by applying the Baade-Wesselink method. Fig. 1 presents the resulting general logP - logR diagram grouping these determinations. The sources for the radii are given by Burki and Meylan (1986). The variable stars in known binaries have been excluded since the presence of a companion biases the radius calculation (Burki, 1984). The determinations marked by arrows are based on the radial velocities by CORAVEL (1m telescope at the Haute-Provence Observatory, France) or/and on the photometry in the Geneva system (40cm and 70cm telescopes at La Silla Observatory, Chile).

scholarly journals Improved Data Reduction Techniques for the ESO CES Plus Reticon Spectra

1988 ◽  
Vol 132 ◽  
pp. 355-360
Author(s):  
B. H. Foing ◽  
L. Crivellari
Keyword(s):  
Radial Velocity ◽  
Data Reduction ◽  
Equivalent Width ◽  
Optimal Recovery ◽  
Special Care ◽  
Velocity Measurements ◽  
Reduction Techniques ◽  
Dark Counts ◽  
Improved Data Reduction

We developed routines for intensity, equivalent width, and radial velocity measurements on CES plus reticon spectra obtained with the ESO 1.4m telescope. In order to achieve the optimal recovery of the signal, the noise has to be minimized by removing any parasitical effect. Special care has been devoted to the correction for remanence effects in the reticon dark counts. Typical results are presented and discussed.

scholarly journals Dealing with activity in RV planet searches

2015 ◽  
Vol 11 (A29A) ◽  
pp. 193-195
Author(s):  
Isabelle Boisse
Keyword(s):  
Time Series ◽  
Radial Velocity ◽  
Radial Velocities ◽  
Velocity Measurements ◽  
Stellar Activity ◽  
The Future

AbstractPrecise radial velocity measurements of a star allow to search for planets. But this method has to face with irregularly time series. Stellar variabilities: pulsation, granulation, stellar activity on a short and long timescale, also modify the measure of the radial velocities. There is indeed a growing literature of controversies on how a signal is interpreted as a planet or due to stellar activity. I present how the star variations change the measured RVs, which techniques and indices are used by several teams to disentangle activity and planets, and the future options that are being studied.

scholarly journals The LAMOST spectroscopic survey of planetary nebulae in M31 and M33

2016 ◽  
Vol 12 (S323) ◽  
pp. 388-389
Author(s):  
Maosheng Xiang ◽  
Xiaowei Liu ◽  
Meng Zhang ◽  
Haibo Yuan ◽  
Zhiying Huo
Keyword(s):  
Radial Velocity ◽  
Planetary Nebulae ◽  
Radial Velocities ◽  
Velocity Measurements ◽  
The Galaxy ◽  
Galaxy Center ◽  
Projected Distance

AbstractWe present LAMOST observations and radial velocity measurements of about 1500 planetary nebulae (PNe) in M31 and M33. Most of the PNe are previously known, but 36 of them are newly discovered in the outskirts of M31, and the furthest one has a projected distance larger than 50 kpc away from the galaxy center. Eighteen objects in the area of M33 are probably newly discovered PNe, and quite a few of them are associated with previously known clusters. For all the 1500 PNe, homogeneous radial velocities are measured from the LAMOST spectra, with a typical uncertainty of a few km s−1.

scholarly journals Some comments on the design of échelle spectrographs using R2 or R4 gratings for precise radial-velocity measurements

1999 ◽  
Vol 170 ◽  
pp. 29-35
Author(s):  
John Hearnshaw ◽  
Norman Rumsey ◽  
Garry Nankivell
Keyword(s):  
Radial Velocity ◽  
High Precision ◽  
Velocity Measurements ◽  
Single Exposure ◽  
Echelle Spectrograph ◽  
Moving Parts

AbstractA new fiber-fed échelle spectrograph (Hercules) is being designed for the 1-m telescope at Mt John University Observatory. The goals are to have a wavelength capability of 380 to 880 nm, covered in a single exposure on a 50-mm square CCD, to have a choice of resolving powers of 35000 or 70000 and to have no moving parts. High precision radialvelocity observations are a major but not the only goal. Designs with both R2 (blaze angle 63.4 deg) and R4 (blaze angle 76 deg) échelle gratings are being considered, in either case with a dimension of 408 mm perpendicular to the grooves.

scholarly journals Precise radial velocities of giant stars

2019 ◽  
Vol 625 ◽  
pp. A22 ◽  
Author(s):  
Katja Reichert ◽  
Sabine Reffert ◽  
Stephan Stock ◽  
Trifon Trifonov ◽  
Andreas Quirrenbach
Keyword(s):  
Radial Velocity ◽  
Statistical Power ◽  
Radial Velocities ◽  
Dynamical Stability ◽  
Published Data ◽  
Data Sets ◽  
Velocity Data ◽  
Velocity Measurements ◽  
Velocity Variations ◽  
Radial Velocity Data

Context. Radial-velocity variations of the K giant star Aldebaran (α Tau) were first reported in the early 1990s. After subsequent analyses, the radial-velocity variability with a period of ∼629 d has recently been interpreted as caused by a planet of several Jovian masses. Aims. We want to further investigate the hypothesis of an extrasolar planet around Aldebaran. Methods. We combine 165 new radial-velocity measurements from Lick Observatory with seven already published data sets comprising 373 radial-velocity measurements. We perform statistical analyses and investigate whether a Keplerian model properly fits the radial velocities. We also perform a dynamical stability analysis for a possible two-planet solution. Furthermore, the possibility of oscillatory convective modes as cause for the observed radial-velocity variability is discussed. Results. As best Keplerian fit to the combined radial-velocity data we obtain an orbit for the hypothetical planet with a smaller period (P = 607 d) and a larger eccentricity (e = 0.33 ± 0.04) than the previously proposed one. However, the residual scatter around that fit is still large, with a standard deviation of 117 ms−1. In 2006/2007, the statistical power of the ∼620 d period showed a temporary but significant decrease. Plotting the growth of power in reverse chronological order reveals that a period around 620 d is clearly present in the newest data but not in the data taken before ∼2006. Furthermore, an apparent phase shift between radial-velocity data and orbital solution is observable at certain times. A two-planet Keplerian fit matches the data considerably better than a single-planet solution, but poses severe dynamical stability issues. Conclusions. The radial-velocity data from Lick Observatory do not further support but in fact weaken the hypothesis of a substellar companion around Aldebaran. Oscillatory convective modes might be a plausible alternative explanation of the observed radial-velocity variations.

scholarly journals High Precision Photometry from EulerCam and TRAPPIST: The Case of WASP-42, WASP-49 and WASP-50

2012 ◽  
Vol 8 (S293) ◽  
pp. 119-121
Author(s):  
Monika Lendl ◽  
Michaël Gillon ◽  
Didier Queloz
Keyword(s):  
Radial Velocity ◽  
High Precision ◽  
Extrasolar Planets ◽  
High Accuracy ◽  
Velocity Measurements ◽  
Very High

AbstractTransiting extrasolar planets provide unmatched insights into the structure and composition of close-in planets. When a planet transits its host star, its radius is known, which together with radial velocity measurements, allows accessing the planetary density. We present results obtained using the Euler and TRAPPIST telescopes that aim at reaching very high accuracy on the parameters derived from transit lightcurves. Here, we show the case of the recently discovered WASP-42b and WASP-49b and new observations of WASP-50b.

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