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J/A+A/605/A103         HD20794 HARPS radial velocities             (Feng+, 2017)

Evidence for at least three planet candidates orbiting HD20794. Feng F., Tuomi M., Jones H.R.A. <Astron. Astrophys. 605, A103 (2017)> =2017A&A...605A.103F (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Planets ; Radial velocities ; Stars, G-type Keywords: methods: statistical - methods: numerical - techniques: radial velocities - stars: individual: HD20794 Abstract: We explore the feasibility of detecting Earth analogs around Sun-like stars using the radial velocity method by investigating one of the largest radial velocities datasets for the one of the most stable radial-velocity stars HD20794. We proceed by disentangling the Keplerian signals from correlated noise and activity-induced variability. We diagnose the noise using the differences between radial velocities measured at different wavelength ranges, so-called "differential radial velocities", as well as the combination of radial velocities measured for other stars to account for instrumental effects. We apply this method to the radial velocities measured by HARPS, and identify four signals at 18, 89, 147 and 330d. The two signals at periods of 18 and 89d are previously reported and are better quantified in this work. The signal at a period of about 147d is reported for the first time, and corresponds to a super-Earth with a minimum mass of 4.59 Earth mass located 0.51AU from HD20794. We also find a significant signal at a period of about 330d corresponding to a super-Earth or Neptune in the habitable zone. Since this signal is close to the annual sampling period and significant periodogram power in some noise proxies are found close to this signal, further observations and analyses are required to confirm it. The analyses of the eccentricity and consistency of signals provide weak evidence for the existence of the previously reported 43d signal and a new signal at a period of about 11.9d with a semi amplitude of 0.4m/s. We find that the detection of a number of signals with radial velocity variations around 0.5m/s likely caused by low mass planet candidates demonstrates the important role of noise modeling in searching for Earth analogs. Description: HARPS radial velocities, activity indices and differential radial velocities for HD 20794. The HARPS spectra are available in the European Southern Observatory archive, and are processed using the TERRA algorithm (Anglada-Escude and Butler, 2012, Cat. J/ApJS/200/15). Objects: ---------------------------------------------- RA (2000) DE Designation(s) ---------------------------------------------- 03 19 55.65 -43 04 11.2 HD 20794 = * e Eri ---------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file hd20794.dat 215 4883 HARPS radial velocities for HD20794 and corresponding noise proxies
See also: J/A+A/534/A58 : HD20794, HD85512, HD192310 HARPS radial velocities (Pepe+ 2011) J/ApJS/200/15 : HARPS-TERRA project. I. (Anglada-Escude+, 2012) Byte-by-byte Description of file: hd20794.dat
Bytes Format Units Label Explanations
1- 11 F11.5 d RJD Reduced Julian Date (JD-2400000) 13- 21 F9.5 m/s RV Radial velocity variation 23- 29 F7.5 m/s e_RV rms uncertainty on radial velocity 31- 39 F9.5 m/s BIS Bisector span of the cross-correlation function 41- 47 F7.5 km/s FWHM Cross-correlation function (CCF) FWHM 49- 55 F7.5 --- Halpha Activity index H-alpha 57- 63 F7.5 --- logR'(HK) Activity index logR'(HK) 65- 71 F7.5 --- NaD1 Activity index Sodium NaD1 73- 79 F7.5 m/s NaD2 Activity index Sodium NaD2 81- 88 F8.5 m/s 3AP2-1 Differential radial velocity 3AP2-1 90- 97 F8.5 m/s 3AP3-2 Differential radial velocity 3AP3-2 99-106 F8.5 m/s 6AP2-1 Differential radial velocity 6AP2-1 108-115 F8.5 m/s 6AP3-2 Differential radial velocity 6AP3-2 117-124 F8.5 m/s 6AP4-3 Differential radial velocity 6AP4-3 126-133 F8.5 m/s 6AP5-4 Differential radial velocity 6AP5-4 135-142 F8.5 m/s 6AP6-5 Differential radial velocity 6AP6-5 144-151 F8.5 m/s 9AP2-1 Differential radial velocity 9AP2-1 153-160 F8.5 m/s 9AP3-2 Differential radial velocity 9AP3-2 162-169 F8.5 m/s 9AP4-3 Differential radial velocity 9AP4-3 171-178 F8.5 m/s 9AP5-4 Differential radial velocity 9AP5-4 180-187 F8.5 m/s 9AP6-5 Differential radial velocity 9AP6-5 189-196 F8.5 m/s 9AP7-6 Differential radial velocity 9AP7-6 198-205 F8.5 m/s 9AP8-7 Differential radial velocity 9AP8-7 207-215 F9.5 m/s 9AP9-8 Differential radial velocity 9AP9-8
Acknowledgements: Fabo Feng, fengfabo(at)gmail.com
(End) Fabo Feng [UH, UK], Patricia Vannier [CDS] 16-May-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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