ELODIE: A spectrograph for accurate radial velocity measurements

Baranne, A.; Queloz, D.; Mayor, M.; Adrianzyk, G.; Knispel, G.; Kohler, D.; Lacroix, Daniel; Meunier, Jean-Pierre; Rimbaud, G.; Vin, A.

doi:10.1051/aas:1996251

Cited by 1,169 publications

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“…Precise radial velocities were derived, together with measurements of the bisector inverse slope (BIS), full width at half maximum (FWHM), and contrast of the HARPS cross-correlation function (CCF - Baranne et al 1996;Pepe et al 2002). These values are useful to diagnose radial-velocity variations that are intrinsic to the star, for instance caused by stellar activity on its different timescales (e.g.…”

Section: Observations and Datamentioning

confidence: 99%

“…In addition to the HARPS data, radial-velocity measurements of HD 219828 were also obtained using the ELODIE (Baranne et al 1996) and SOPHIE (Perruchot et al 2008) crossdispersor fiber-fed echelle spectrographs, mounted on the 1.93 m telescope at the Observatoire de Haute-Provence (OHP) 1 . Albeit with a lower precision when compared with HARPS, the radial velocities derived using these instruments are useful to constrain the period and eccentricity of the long-period companion (see Sect.…”

Section: Observations and Datamentioning

confidence: 99%

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An extreme planetary system around HD 219828

Santos

Santerne

Faria

et al. 2016

A&A

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Context. With about 2000 extrasolar planets confirmed, the results show that planetary systems have a whole range of unexpected properties. This wide diversity provides fundamental clues to the processes of planet formation and evolution. Aims. We present a full investigation of the HD 219828 system, a bright metal-rich star for which a hot Neptune has previously been detected. Methods. We used a set of HARPS, SOPHIE, and ELODIE radial velocities to search for the existence of orbiting companions to HD 219828. The spectra were used to characterise the star and its chemical abundances, as well as to check for spurious, activity induced signals. A dynamical analysis is also performed to study the stability of the system and to constrain the orbital parameters and planet masses. Results. We announce the discovery of a long period (P = 13.1 yr) massive (m sin i = 15.1 M Jup ) companion (HD 219828 c) in a very eccentric orbit (e = 0.81). The same data confirms the existence of a hot Neptune, HD 219828 b, with a minimum mass of 21 M ⊕ and a period of 3.83 days. The dynamical analysis shows that the system is stable, and that the equilibrium eccentricity of planet b is close to zero. Conclusions. The HD 219828 system is extreme and unique in several aspects. First, ammong all known exoplanet systems it presents an unusually high mass ratio. We also show that systems like HD 219828, with a hot Neptune and a long-period massive companion are more frequent than similar systems with a hot Jupiter instead. This suggests that the formation of hot Neptunes follows a different path than the formation of their hot jovian counterparts. The high mass, long period, and eccentricity of HD 219828 c also make it a good target for Gaia astrometry as well as a potential target for atmospheric characterisation, using direct imaging or high-resolution spectroscopy. Astrometric observations will allow us to derive its real mass and orbital configuration. If a transit of HD 219828 b is detected, we will be able to fully characterise the system, including the relative orbital inclinations. With a clearly known mass, HD 219828 c may become a benchmark object for the range in between giant planets and brown dwarfs.

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Section: Observations and Datamentioning

confidence: 99%

Section: Observations and Datamentioning

confidence: 99%

An extreme planetary system around HD 219828

Santos

Santerne

Faria

et al. 2016

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“…We determined RVs using a weighted cross-correlation method, following the procedure of Baranne et al (1996) and Pepe et al (2005), with a numerical mask constructed from the solar spectrum atlas corresponding to a G2 dwarf star. This standard mask is well adapted to the F8-type spectrum of the primary star.…”

Section: Observationsmentioning

confidence: 99%

Refined parameters and spectroscopic transit of the super-massive planet HD 147506b

Loeillet

Shporer

Bouchy

et al. 2008

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In this paper, we report a refined determination of the orbital parameters and the detection of the Rossiter-McLaughlin effect of the recently discovered transiting exoplanet HD 147506b (HAT-P-2b). The large orbital eccentricity at the short orbital period of this exoplanet is unexpected and is distinguishing from other known transiting exoplanets. We performed high-precision radial velocity spectroscopic observations of HD 147506 (HAT-P-2) with the new spectrograph SOPHIE, mounted on the 1.93 m telescope at the Haute-Provence observatory (OHP). We obtained 63 new measurements, including 35 on May 14 and 20 on June 11, when the planet was transiting its parent star. The radial velocity (RV) anomaly observed illustrates that HAT-P-2b orbital motion is set in the same direction as its parent star spin. The sky-projected angle between the normal of the orbital plane and the stellar spin axis, λ = 0.2 +12.2 −12.5• , is consistent with zero. The planetary and stellar radii were re-determined, yielding R p = 0.951 +0.039 −0.053 R Jup , R s = 1.416 +0.040 −0.062 R . The mass (M p = 8.62 +0.39 −0.55 M Jup ) and radius of HAT-P-2b indicate a density of 12.5 +2.6 −3.6 g cm −3 , suggesting an object in between the known close-in planets with typical density of the order of 1 g cm −3 , and the very low-mass stars, with density greater than 50 g cm −3 .

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“…Martins et al (2013) showed that the cross-correlation function (CCF) can be used to mathematically enhance the signalto-noise ratio (S/N) of our observations to a level where the extremely low S/N planetary signal can be recovered. The CCF of a spectrum with a binary mask (Baranne et al 1996) has been extensively tested in detecting exoplanets with the radial velocities method. Briefly, this technique corresponds to mapping the degree of similarity between the stellar spectrum and a binary mask (representing the stellar type), which increases the S/N of the data by a factor proportional to the square root of the number of spectral lines identified in the mask.…”

Section: Introductionmentioning

confidence: 99%

Evidence for a spectroscopic direct detection of reflected light from 51 Pegasi b

Martins

Santos

Figueira

et al. 2015

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Context. The detection of reflected light from an exoplanet is a difficult technical challenge at optical wavelengths. Even though this signal is expected to replicate the stellar signal, not only is it several orders of magnitude fainter, but it is also hidden among the stellar noise. Aims. We apply a variant of the cross-correlation technique to HARPS observations of 51 Peg to detect the reflected signal from planet 51 Peg b. Methods. Our method makes use of the cross-correlation function (CCF) of a binary mask with high-resolution spectra to amplify the minute planetary signal that is present in the spectra by a factor proportional to the number of spectral lines when performing the cross correlation. The resulting cross-correlation functions are then normalized by a stellar template to remove the stellar signal. Carefully selected sections of the resulting normalized CCFs are stacked to increase the planetary signal further. The recovered signal allows probing several of the planetary properties, including its real mass and albedo. Results. We detect evidence for the reflected signal from planet 51 Peg b at a significance of 3σ noise . The detection of the signal permits us to infer a real mass of 0.46 +0.06 −0.01 M Jup (assuming a stellar mass of 1.04 M Sun ) for the planet and an orbital inclination of 80 +10 −19 degrees. The analysis of the data also allows us to infer a tentative value for the (radius-dependent) geometric albedo of the planet. The results suggest that 51Peg b may be an inflated hot Jupiter with a high albedo (e.g., an albedo of 0.5 yields a radius of 1.9 ± 0.3 R Jup for a signal amplitude of 6.0 ± 0.4 × 10 −5 ). Conclusions. We confirm that the method we perfected can be used to retrieve an exoplanet's reflected signal, even with current observing facilities. The advent of next generation of instruments (e.g. VLT-ESO/ESPRESSO) and observing facilities (e.g. a new generation of ELT telescopes) will yield new opportunities for this type of technique to probe deeper into exoplanets and their atmospheres.

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ELODIE: A spectrograph for accurate radial velocity measurements

Cited by 1,169 publications

References 15 publications

An extreme planetary system around HD 219828

An extreme planetary system around HD 219828

Refined parameters and spectroscopic transit of the super-massive planet HD 147506b

Evidence for a spectroscopic direct detection of reflected light from 51 Pegasi b

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